Supporting information for this article is given via a link at the end of the document. It includ... more Supporting information for this article is given via a link at the end of the document. It includes Figures S1-S9, Tables S1-S2, NMR spectra of compounds, and detailed computational results.
A series of pyridinium-betaine like molecules has been reported; one family of molecules is built... more A series of pyridinium-betaine like molecules has been reported; one family of molecules is built with a benzimidazole core and a second one with a pyrimidine moiety. The title compounds were prepared by mixing 2-chlorobenzimidazole or 2-bromopyrimidine with the corresponding pyridines (pyridine, 4-tert-butylpyridine, 4-hydroxypyridine, potassium 4-trifluoroboratepyridine, 4-dimethylaminopyridine) in acetonitrile or DMSO at high temperatures. The novel compounds were characterized by spectroscopic methods. The UV-Vis. and fluorescence features are reported as well. Preliminary photoluminescence results showed broadband emissions as common feature ascribed to the compounds containing benzimidazole ring. Some of the spectra nearly span over the whole visible spectral range, which pave the way to real opportunities to design single-component panchromatic emitters.
The synthesis, optical resolution through derivatization, characterization, and utilization of a ... more The synthesis, optical resolution through derivatization, characterization, and utilization of a new helical bis(phosphinite gold) complex derived from HELIXOL are described. By using an efficient cobalt catalyst, neither irradiation nor high catalytic loading was required to access the helicene of interest.
Phosphine gold(I) arylacetylide complexes equipped with a central bis-urea moiety form 1D hydroge... more Phosphine gold(I) arylacetylide complexes equipped with a central bis-urea moiety form 1D hydrogen-bonded polymeric assemblies in solution which do not display any optical activity. Chiral co-assemblies are formed by simple addition of an enantiopure (metal-free) complementary monomer. Although exhibiting an intrinsically achiral linear geometry, the gold(I) arylacetylide fragment is located in the chiral environment displayed by the hydrogen-bonded co-assemblies as demonstrated by induced circular dichroism (ICD). Inducing chirality to metal complexes, [1] nanoparticles [2] and surfaces [3] is a central topic of chemical sciences motivated by important applications in the fields of chiral recognition, sensing, and catalysis. Notably, non-covalent interactions have been designed to place intrinsically achiral metal complexes in the chiral environment provided by various types of chiral species. [4] Chirality induction is usually confirmed by the presence of a Cotton effect in the spectral region in which only the metal complex absorbs. [5] The observation of such an induced circular dichroism [6] (ICD) signal reflects the specific electronic charge distribution within the thus formed chiral supramolecular entities. Gold(I) species have attracted considerable attention since the discovery of their catalytic and spectroscopic properties in solution and their potential use in a wide range of applications. [7] However, since gold(I) has a known preference for a linear coordination geometry, the induction of chirality in gold(I) complexes is actually a non-trivial task. In the realm of asymmetric catalysis, an effective degree of enantioinduction is observed only for a few classes of chiral covalent ligands or anions. [8] Alternatively, ICD signals have been observed for achiral gold complexes embedded into chiral surfactants [9] or self-assembled within a semicrystalline chiral organized structure. [10] Obviously, the incorporation of gold complexes in other chiral matrices can offer interesting alternatives. [11] Notably, chiral supramolecular polymers constitute robust platforms for chirality transfer and amplification. [12] Supramolecular polymers are often in dynamic exchange and co-polymers can be prepared by simply mixing different types of complementary monomers. Since the chiral information is
A series of bipyridyl (bpy) Pt(II) complexes with π-bonded catecholate (cat) [(bpy)Pt(LM)][BF4]n ... more A series of bipyridyl (bpy) Pt(II) complexes with π-bonded catecholate (cat) [(bpy)Pt(LM)][BF4]n (2-5) (LM = Cp*Rh(cat), n = 2; Cp*Ir(cat), n = 2; Cp*Ru(cat), n = 1; and (C6H6)Ru(cat), n = 2) were prepared and fully characterized. The molecular structures of the four compounds were determined and showed that the solid-state packing is different and dependent on the π-bonded catecholate unit. For instance, while the (bpy)Pt(II) complexes 2 and 3 with rhodium and iridium catecholates did not show any Pt···Pt interactions those with the ruthenium catecholates 4 and 5 showed the presence of Pt···Pt and π-π interactions among individual units and generated one- and two-dimensional supramolecular chains. The photophysical properties of these compounds 2-5 were investigated and showed that all compounds are luminescent at low temperature, in contrast to the well-known parent compound [(C6H4O2)Pt(bpy)] (1), which is weakly luminescent at 77 K. Time-dependent density functional theory studie...
ABSTRACT The oxidative Glaser-Hay coupling reaction of terminal alkynes is a very important react... more ABSTRACT The oxidative Glaser-Hay coupling reaction of terminal alkynes is a very important reaction in organic chemistry to achieve the synthesis of diyne compounds. In general the reaction is performed under homogeneous conditions using Cu(I) or Cu(II) salts in the presence of a reagent such as tetramethylethylenediamine (TMEDA), which can bind to copper ions, an organic base and dioxygen. Although this reaction is known for a longtime, the mechanism is still under discussion. Pursuing our investigations on the use of apatites as catalysts for organic reactions we highlight in this work how it is possible to catalyze the Glaser-Hay reaction under heterogeneous conditions using a Cu-modified hydroxyapatite (Cu-HAp). With several para-substituted phenyl-acetylenes and alkynols we show that Cu-HAp acts as catalyst for C-C coupling reactions leading to diyne derivatives in high yields without using auxiliary chelating molecules and organic bases. These heterogeneous conditions allow an easy recovery of the catalyst and simplify the purification work-up.
We recently described the synthesis of p-benzoquinone complexes of rhodium and iridium [Cp*M(p-be... more We recently described the synthesis of p-benzoquinone complexes of rhodium and iridium [Cp*M(p-benzoquinone)] (M = Rh (1a); M = Ir (1b)) as well as the related [Cp*Ir(o-dithiobenzoquinone )] and [Cp*Ir(p-dithiobenzoquinone)] complexes (Figure 1a).(1) The latter were ...
A novel type of metalated phosphino ligands, [Cp*Ru-(η 6-arene-PPh 2)][OTf] (2a-d-OTf), has been ... more A novel type of metalated phosphino ligands, [Cp*Ru-(η 6-arene-PPh 2)][OTf] (2a-d-OTf), has been prepared in which the-PPh 2 unit is attached to a metalated π-arene platform. This unique class of ligands 2a-d are converted to open-sided cationic gold complexes 3a-d upon treatment with [AuCl(tht)]. The structure of one of these compounds, [Cp*Ru(η 6-C 6 H 5-PPh 2-Au-Cl)][OTf] (3a-OTf), was ascertained by single-crystal X-ray diffraction. Preliminary studies suggest that cationic complex 3a is active in metal-catalyzed cycloisomerization reactions. Gold complexes have received much attention due to their importance in several applications such as luminescence, supramolecular chemistry, and nanoparticles, and more recently in catalysis. 1 Indeed in the past decade, homogeneous gold catalysis has emerged as a powerful tool for novel organic transformations, thus providing a variety of CC bond-forming reactions for the synthesis of complex chemical structures. 2 In this context, efforts have been devoted to prepare new gold complexes by tuning the electronic and/or
A novel heteroleptic cyclometalated iridium(III) complex with one picolinic acid derivative beari... more A novel heteroleptic cyclometalated iridium(III) complex with one picolinic acid derivative bearing a pendant terminal alkynyl tether has been prepared following a new synthetic route. This pendant alkynyl tether can be further engaged in palladium C?C coupling reactions, allowing its grafting to a Keggin-type polyoxometalate and thus providing a unique iridio-POM conjugate.
A novel series of π-complexes of phosphino ligands, [Cp*Ru(η 6-arene-PAr 2)][OTf], has been prepa... more A novel series of π-complexes of phosphino ligands, [Cp*Ru(η 6-arene-PAr 2)][OTf], has been prepared in which the diarylphosphine unit is attached to a metalated πarene scaffold. These organometallic phosphino ligands display either an electron-donating methyl group (−PAr 2 = −P(ptol) 2) or electron-withdrawing trifluoromethyl group (−PAr 2 = −P(p-C 6 H 4 CF 3) 2). This unique class of metallo ligands was converted to heterodinuclear gold complexes upon treatment with [AuCl(tht)]. The molecular structures of [Cp*Ru(η 6-p-CH 3 C 6 H 4-P(p-tol) 2-Au-Cl)][OTf] and [Cp*Ru(η 6-C 6 H 5-P(p-C 6 H 4 CF 3) 2)-Au-Cl][OTf] were ascertained by single-crystal X-ray diffraction. A comparative study of these structures with that of [Cp*Ru(η 6-C 6 H 5-PPh 2-Au-Cl)][OTf] previously reported revealed important information about the electronic nature of the gold center when it is bonded to a −PPh 2 , −P(p-tol) 2 , or −P(p-C 6 H 4 CF 3) 2 metallo ligand. DFT computations also shed light on the effect of [Cp*Ru + ] coordination to [AuCl(PAr 3)] precatalysts. Several complexes of the family with electron-donating and-withdrawing groups were evaluated toward cycloisomerization reactions of a classical N-tethered 1,6-enyne. These results are presented and discussed.
We report the synthesis of π-bonded ruthenium, rhodium, and iridium o-benzoquinones [Cp*M(o-C(6)H... more We report the synthesis of π-bonded ruthenium, rhodium, and iridium o-benzoquinones [Cp*M(o-C(6)H(4)O(2))](n) [M = Ru (2), n = 1-; Rh (3), n = 0; Ir (4), n = 0] following a novel synthetic procedure. Compounds 2-4 were fully characterized by spectroscopic methods and used as chelating organometallic linkers, "OM-linkers", toward luminophore bricks such as Ru(bpy)(2)(2+), Rh(ppy)(2)(+), and Ir(ppy)(2)(+) (bpy = 2,2'-bipyridine; ppy = 2-phenylpyridine) for the design of a novel family of octahedral bimetallic complexes of the general formula [(L-L)(2)M(OM-linkers)][X](m) (X = counteranion; m = 0, 1, 2) whose luminescent properties depend on the choice of the OM-linker and the luminophore brick. Thus, dinuclear assemblies such as [(bpy)(2)Ru(2)][OTf] (5-OTf), [(bpy)(2)Ru(2)][Δ-TRISPHAT] (5-ΔT) {TRISPHAT = tris[tetrachlorobenzene-1,2-bis(olato)]phosphate}, [(bpy)(2)Ru(3)][OTf](2) (6-OTf), [(bpy)(2)Ru(4)][OTf](2) (7-OTf), [(bpy)(2)Ru(4)][Δ-TRISPHAT](2) (7-ΔT), [(ppy)(2)Rh(2)] (8), [(ppy)(2)Rh(3)][OTf] (9-OTf), [(ppy)(2)Rh(4)][OTf] (10-OTf), [(ppy)(2)Rh(4)][Δ-TRISPHAT] (10-ΔT), [(ppy)(2)Ir(2)] (11), [(ppy)(2)Ir(3)][OTf] (12-OTf), [(ppy)(2)Ir(4)][OTf] (13-OTf), and [(ppy)(2)Ir(4)][Δ-TRISPHAT] (13-ΔT) were prepared and fully characterized. The X-ray molecular structures of three of them, i.e., 5-OTf, 8, and 11, were determined. The structures displayed a main feature: for instance, the two oxygen centers of the OM-linker [Cp*Ru(o-C(6)H(4)O(2))](-) (2) chelate the octahedral chromophore metal center, whether it be ruthenium, rhodium, or iridium. Further, the carbocycle of the OM-linker 2 adopts a η(4)-quinone form but with some catecholate contribution due to metal coordination. All of these binuclear assemblies showed a wide absorption window that tailed into the near-IR (NIR) region, in particular in the case of the binuclear ruthenium complex 5-OTf with the anionic OM-linker 2. The latter feature is no doubt related to the effect of the OM-linker, which lights up the luminescence in these homo- and heterobinuclear compounds, while no effect has been observed on the UV-visible and emission properties because of the counteranion, whether it be triflate (OTf) or Δ-TRISPHAT. At low temperature, all of these compounds become luminescent; remarkably, the o-quinonoid linkers [Cp*M(o-C(6)H(4)O(2))](n) (2-4) turn on red and NIR phosphorescence in the binuclear octahedral species 5-7. This trend was even more observable when the ruthenium OM-linker 2 was employed. These assemblies hold promise as NIR luminescent materials, in contrast to those made from organic 1,2-dioxolene ligands that conversely are not emissive.
Prior to this work the self-assembly of 13-D networks, was reported using the only known organom... more Prior to this work the self-assembly of 13-D networks, was reported using the only known organometallic linker [(η 4 -benzoquinone)Mn(CO) 3 ][Na].8 However, none of these polymers contained silver cations. Thus, our 1-D polymers 2a,b are the first coordination polymers with the neutral ...
Most of these examples reported so far involve coordination assemblies, where this kind of noncov... more Most of these examples reported so far involve coordination assemblies, where this kind of noncovalent interaction occurs between the electron-deficient aromatic rings of the coordinated ligands and the counteranions of the assemblies.57 However, we also note the existence of some ...
Steady-state irradiation under visible light of a covalent Ir(III)-photosensitized polyoxotungsta... more Steady-state irradiation under visible light of a covalent Ir(III)-photosensitized polyoxotungstate is reported. In the presence of a sacrificial electron donor, the photolysis leads to the very efficient photoreduction of the polyoxometalate. Successive formation of the one-electron and two-electron reduced species, which are unambiguously identified by comparison with spectroelectrochemical measurements, is observed with a significantly faster rate reaction for the formation of the oneelectron reduced species. The kinetics of the photoreduction, which are correlated to the reduction potentials of the polyoxometalate (POM), can be finely tuned by the presence of an acid. Indeed light-driven formation of the two-electron reduced POM is considerably facilitated in the presence of acetic acid. The system is also able to perform photocatalytic hydrogen production under visible light without significant loss of performance over more than 1 week of continuous photolysis and displays higher photocatalytic efficiency than the related multi-component system, outlining the decisive effect of the covalent bonding between the POM and the photosensitizer. This functional and modular system constitutes a promising step for the development of charge photoaccumulation devices and subsequent photoelectrocatalysts for artificial photosynthesis. Photoconversion of light into chemical fuels is emerging as a major scientific challenge. 1-4 In the past decades, molecular approaches have mostly focused on one hand on the design of photosensitive systems displaying long-lived photo-induced charge separation states to permit further electron transfers 5-10 and, on the other hand, on catalysts able to use these photogenerated charges for achieving either oxygen 11-18 or hydrogen evolution. 19-24 As these two reactions are multi-electronic processes while photosensitizers deliver electrons and holes sequentially, the charges need to be directed to a charge accumulation site. 25 However, only a few molecular photoactive systems with a designed charge accumulation site have been described so far. 26-30 Another requirement is crucial for efficient charge accumulation in such systems: when partially filled, the reservoir should not interfere with the photoactive moiety. Indeed, in classical donor-acceptor (D-A) systems, the electron acceptor, once reduced, potentially becomes an electron donor and often displays lightabsorbing properties. Thus it may act, in a subsequent light-driven process, as a deleterious
The first luminescent platinum(ii) complex bearing phosphinine co-ligands with a long-lived emiss... more The first luminescent platinum(ii) complex bearing phosphinine co-ligands with a long-lived emission from a phosphinine-localised triplet excited state is reported.
Unlike p-dithiobenzoquinone (), which is extremely reactive and has never been isolated, the meta... more Unlike p-dithiobenzoquinone (), which is extremely reactive and has never been isolated, the metal-stabilised p-dithiobenzoquinone [Cp*Ir(eta4-C6H4S2)] () was prepared and used as an efficient organometallic linker to construct novel supramolecular assemblies. Treatment of with the electrophilic Pt(II)(terpy) building blocks produced the supramolecular assembly {[Pt(terpy){Cp*Ir-p-(eta4-C6H4S2)}Pt(terpy)][OTf]4}n (), which was fully characterised and its molecular structure was determined by X-ray crystallography. The structure of revealed the presence of pi-pi and Pt[dot dot dot]Pt interactions among individual molecules describing a 1D chain. Complex showed unusual UV/Vis absorption and luminescence behaviour at low temperature, imparted from self-aggregation mediated by pi-pi and Pt...Pt interactions.
Electron-deficient arenes are now recognized as potent anion receptors, mainly through the establ... more Electron-deficient arenes are now recognized as potent anion receptors, mainly through the establishment of π-anion interactions. Cyclopentadienyl ligands (Cp's) also belong to the family of arenes that exhibit very low electron density at their centroid due to the presence of the ...
The chiral octahedral bimetallic assemblies [(bpy) 2 Ru(o-L Ir)][CF 3 SO 3 ] 2 (2), [(ppy) 2 Rh(o... more The chiral octahedral bimetallic assemblies [(bpy) 2 Ru(o-L Ir)][CF 3 SO 3 ] 2 (2), [(ppy) 2 Rh(o-L Ir)][NO 3 ] (7) and [(ppy) 2 Ir(o-L Ir)][NO 3 ] (8) featuring chelating organometallic linker [Cp*Ir(h 4-o-benzoquinone)] (o-L Ir) have been prepared and fully characterized. Anion metathesis following a convenient procedure allowed the preparation of the related diastereomers [D-(bpy) 2 Ru(o-L Ir)][D-TRISPHAT] 2 (2a) and [L-(bpy) 2 Ru (o-L Ir)][D-TRISPHAT] 2 (2b) as well as the octahedral rhodium [(D, L)-(ppy) 2 Rh (o-L Ir)][D-TRISPHAT] (7a, 7b) and iridium [(D, L)-(ppy) 2 Ir(o-L Ir)][D-TRISPHAT] (8a, 8b) bimetallic assemblies. 1 H NMR studies in solution carried out on these compounds showed different behavior. For instance, the rhodium and iridium compounds exhibited weak chiral recognition in contrast the ruthenium compounds allowed facile differentiation between the two diastereomers suggesting that chiral recognition occurs between the enantiopure anion and the cationic part of the molecule.
Supporting information for this article is given via a link at the end of the document. It includ... more Supporting information for this article is given via a link at the end of the document. It includes Figures S1-S9, Tables S1-S2, NMR spectra of compounds, and detailed computational results.
A series of pyridinium-betaine like molecules has been reported; one family of molecules is built... more A series of pyridinium-betaine like molecules has been reported; one family of molecules is built with a benzimidazole core and a second one with a pyrimidine moiety. The title compounds were prepared by mixing 2-chlorobenzimidazole or 2-bromopyrimidine with the corresponding pyridines (pyridine, 4-tert-butylpyridine, 4-hydroxypyridine, potassium 4-trifluoroboratepyridine, 4-dimethylaminopyridine) in acetonitrile or DMSO at high temperatures. The novel compounds were characterized by spectroscopic methods. The UV-Vis. and fluorescence features are reported as well. Preliminary photoluminescence results showed broadband emissions as common feature ascribed to the compounds containing benzimidazole ring. Some of the spectra nearly span over the whole visible spectral range, which pave the way to real opportunities to design single-component panchromatic emitters.
The synthesis, optical resolution through derivatization, characterization, and utilization of a ... more The synthesis, optical resolution through derivatization, characterization, and utilization of a new helical bis(phosphinite gold) complex derived from HELIXOL are described. By using an efficient cobalt catalyst, neither irradiation nor high catalytic loading was required to access the helicene of interest.
Phosphine gold(I) arylacetylide complexes equipped with a central bis-urea moiety form 1D hydroge... more Phosphine gold(I) arylacetylide complexes equipped with a central bis-urea moiety form 1D hydrogen-bonded polymeric assemblies in solution which do not display any optical activity. Chiral co-assemblies are formed by simple addition of an enantiopure (metal-free) complementary monomer. Although exhibiting an intrinsically achiral linear geometry, the gold(I) arylacetylide fragment is located in the chiral environment displayed by the hydrogen-bonded co-assemblies as demonstrated by induced circular dichroism (ICD). Inducing chirality to metal complexes, [1] nanoparticles [2] and surfaces [3] is a central topic of chemical sciences motivated by important applications in the fields of chiral recognition, sensing, and catalysis. Notably, non-covalent interactions have been designed to place intrinsically achiral metal complexes in the chiral environment provided by various types of chiral species. [4] Chirality induction is usually confirmed by the presence of a Cotton effect in the spectral region in which only the metal complex absorbs. [5] The observation of such an induced circular dichroism [6] (ICD) signal reflects the specific electronic charge distribution within the thus formed chiral supramolecular entities. Gold(I) species have attracted considerable attention since the discovery of their catalytic and spectroscopic properties in solution and their potential use in a wide range of applications. [7] However, since gold(I) has a known preference for a linear coordination geometry, the induction of chirality in gold(I) complexes is actually a non-trivial task. In the realm of asymmetric catalysis, an effective degree of enantioinduction is observed only for a few classes of chiral covalent ligands or anions. [8] Alternatively, ICD signals have been observed for achiral gold complexes embedded into chiral surfactants [9] or self-assembled within a semicrystalline chiral organized structure. [10] Obviously, the incorporation of gold complexes in other chiral matrices can offer interesting alternatives. [11] Notably, chiral supramolecular polymers constitute robust platforms for chirality transfer and amplification. [12] Supramolecular polymers are often in dynamic exchange and co-polymers can be prepared by simply mixing different types of complementary monomers. Since the chiral information is
A series of bipyridyl (bpy) Pt(II) complexes with π-bonded catecholate (cat) [(bpy)Pt(LM)][BF4]n ... more A series of bipyridyl (bpy) Pt(II) complexes with π-bonded catecholate (cat) [(bpy)Pt(LM)][BF4]n (2-5) (LM = Cp*Rh(cat), n = 2; Cp*Ir(cat), n = 2; Cp*Ru(cat), n = 1; and (C6H6)Ru(cat), n = 2) were prepared and fully characterized. The molecular structures of the four compounds were determined and showed that the solid-state packing is different and dependent on the π-bonded catecholate unit. For instance, while the (bpy)Pt(II) complexes 2 and 3 with rhodium and iridium catecholates did not show any Pt···Pt interactions those with the ruthenium catecholates 4 and 5 showed the presence of Pt···Pt and π-π interactions among individual units and generated one- and two-dimensional supramolecular chains. The photophysical properties of these compounds 2-5 were investigated and showed that all compounds are luminescent at low temperature, in contrast to the well-known parent compound [(C6H4O2)Pt(bpy)] (1), which is weakly luminescent at 77 K. Time-dependent density functional theory studie...
ABSTRACT The oxidative Glaser-Hay coupling reaction of terminal alkynes is a very important react... more ABSTRACT The oxidative Glaser-Hay coupling reaction of terminal alkynes is a very important reaction in organic chemistry to achieve the synthesis of diyne compounds. In general the reaction is performed under homogeneous conditions using Cu(I) or Cu(II) salts in the presence of a reagent such as tetramethylethylenediamine (TMEDA), which can bind to copper ions, an organic base and dioxygen. Although this reaction is known for a longtime, the mechanism is still under discussion. Pursuing our investigations on the use of apatites as catalysts for organic reactions we highlight in this work how it is possible to catalyze the Glaser-Hay reaction under heterogeneous conditions using a Cu-modified hydroxyapatite (Cu-HAp). With several para-substituted phenyl-acetylenes and alkynols we show that Cu-HAp acts as catalyst for C-C coupling reactions leading to diyne derivatives in high yields without using auxiliary chelating molecules and organic bases. These heterogeneous conditions allow an easy recovery of the catalyst and simplify the purification work-up.
We recently described the synthesis of p-benzoquinone complexes of rhodium and iridium [Cp*M(p-be... more We recently described the synthesis of p-benzoquinone complexes of rhodium and iridium [Cp*M(p-benzoquinone)] (M = Rh (1a); M = Ir (1b)) as well as the related [Cp*Ir(o-dithiobenzoquinone )] and [Cp*Ir(p-dithiobenzoquinone)] complexes (Figure 1a).(1) The latter were ...
A novel type of metalated phosphino ligands, [Cp*Ru-(η 6-arene-PPh 2)][OTf] (2a-d-OTf), has been ... more A novel type of metalated phosphino ligands, [Cp*Ru-(η 6-arene-PPh 2)][OTf] (2a-d-OTf), has been prepared in which the-PPh 2 unit is attached to a metalated π-arene platform. This unique class of ligands 2a-d are converted to open-sided cationic gold complexes 3a-d upon treatment with [AuCl(tht)]. The structure of one of these compounds, [Cp*Ru(η 6-C 6 H 5-PPh 2-Au-Cl)][OTf] (3a-OTf), was ascertained by single-crystal X-ray diffraction. Preliminary studies suggest that cationic complex 3a is active in metal-catalyzed cycloisomerization reactions. Gold complexes have received much attention due to their importance in several applications such as luminescence, supramolecular chemistry, and nanoparticles, and more recently in catalysis. 1 Indeed in the past decade, homogeneous gold catalysis has emerged as a powerful tool for novel organic transformations, thus providing a variety of CC bond-forming reactions for the synthesis of complex chemical structures. 2 In this context, efforts have been devoted to prepare new gold complexes by tuning the electronic and/or
A novel heteroleptic cyclometalated iridium(III) complex with one picolinic acid derivative beari... more A novel heteroleptic cyclometalated iridium(III) complex with one picolinic acid derivative bearing a pendant terminal alkynyl tether has been prepared following a new synthetic route. This pendant alkynyl tether can be further engaged in palladium C?C coupling reactions, allowing its grafting to a Keggin-type polyoxometalate and thus providing a unique iridio-POM conjugate.
A novel series of π-complexes of phosphino ligands, [Cp*Ru(η 6-arene-PAr 2)][OTf], has been prepa... more A novel series of π-complexes of phosphino ligands, [Cp*Ru(η 6-arene-PAr 2)][OTf], has been prepared in which the diarylphosphine unit is attached to a metalated πarene scaffold. These organometallic phosphino ligands display either an electron-donating methyl group (−PAr 2 = −P(ptol) 2) or electron-withdrawing trifluoromethyl group (−PAr 2 = −P(p-C 6 H 4 CF 3) 2). This unique class of metallo ligands was converted to heterodinuclear gold complexes upon treatment with [AuCl(tht)]. The molecular structures of [Cp*Ru(η 6-p-CH 3 C 6 H 4-P(p-tol) 2-Au-Cl)][OTf] and [Cp*Ru(η 6-C 6 H 5-P(p-C 6 H 4 CF 3) 2)-Au-Cl][OTf] were ascertained by single-crystal X-ray diffraction. A comparative study of these structures with that of [Cp*Ru(η 6-C 6 H 5-PPh 2-Au-Cl)][OTf] previously reported revealed important information about the electronic nature of the gold center when it is bonded to a −PPh 2 , −P(p-tol) 2 , or −P(p-C 6 H 4 CF 3) 2 metallo ligand. DFT computations also shed light on the effect of [Cp*Ru + ] coordination to [AuCl(PAr 3)] precatalysts. Several complexes of the family with electron-donating and-withdrawing groups were evaluated toward cycloisomerization reactions of a classical N-tethered 1,6-enyne. These results are presented and discussed.
We report the synthesis of π-bonded ruthenium, rhodium, and iridium o-benzoquinones [Cp*M(o-C(6)H... more We report the synthesis of π-bonded ruthenium, rhodium, and iridium o-benzoquinones [Cp*M(o-C(6)H(4)O(2))](n) [M = Ru (2), n = 1-; Rh (3), n = 0; Ir (4), n = 0] following a novel synthetic procedure. Compounds 2-4 were fully characterized by spectroscopic methods and used as chelating organometallic linkers, "OM-linkers", toward luminophore bricks such as Ru(bpy)(2)(2+), Rh(ppy)(2)(+), and Ir(ppy)(2)(+) (bpy = 2,2'-bipyridine; ppy = 2-phenylpyridine) for the design of a novel family of octahedral bimetallic complexes of the general formula [(L-L)(2)M(OM-linkers)][X](m) (X = counteranion; m = 0, 1, 2) whose luminescent properties depend on the choice of the OM-linker and the luminophore brick. Thus, dinuclear assemblies such as [(bpy)(2)Ru(2)][OTf] (5-OTf), [(bpy)(2)Ru(2)][Δ-TRISPHAT] (5-ΔT) {TRISPHAT = tris[tetrachlorobenzene-1,2-bis(olato)]phosphate}, [(bpy)(2)Ru(3)][OTf](2) (6-OTf), [(bpy)(2)Ru(4)][OTf](2) (7-OTf), [(bpy)(2)Ru(4)][Δ-TRISPHAT](2) (7-ΔT), [(ppy)(2)Rh(2)] (8), [(ppy)(2)Rh(3)][OTf] (9-OTf), [(ppy)(2)Rh(4)][OTf] (10-OTf), [(ppy)(2)Rh(4)][Δ-TRISPHAT] (10-ΔT), [(ppy)(2)Ir(2)] (11), [(ppy)(2)Ir(3)][OTf] (12-OTf), [(ppy)(2)Ir(4)][OTf] (13-OTf), and [(ppy)(2)Ir(4)][Δ-TRISPHAT] (13-ΔT) were prepared and fully characterized. The X-ray molecular structures of three of them, i.e., 5-OTf, 8, and 11, were determined. The structures displayed a main feature: for instance, the two oxygen centers of the OM-linker [Cp*Ru(o-C(6)H(4)O(2))](-) (2) chelate the octahedral chromophore metal center, whether it be ruthenium, rhodium, or iridium. Further, the carbocycle of the OM-linker 2 adopts a η(4)-quinone form but with some catecholate contribution due to metal coordination. All of these binuclear assemblies showed a wide absorption window that tailed into the near-IR (NIR) region, in particular in the case of the binuclear ruthenium complex 5-OTf with the anionic OM-linker 2. The latter feature is no doubt related to the effect of the OM-linker, which lights up the luminescence in these homo- and heterobinuclear compounds, while no effect has been observed on the UV-visible and emission properties because of the counteranion, whether it be triflate (OTf) or Δ-TRISPHAT. At low temperature, all of these compounds become luminescent; remarkably, the o-quinonoid linkers [Cp*M(o-C(6)H(4)O(2))](n) (2-4) turn on red and NIR phosphorescence in the binuclear octahedral species 5-7. This trend was even more observable when the ruthenium OM-linker 2 was employed. These assemblies hold promise as NIR luminescent materials, in contrast to those made from organic 1,2-dioxolene ligands that conversely are not emissive.
Prior to this work the self-assembly of 13-D networks, was reported using the only known organom... more Prior to this work the self-assembly of 13-D networks, was reported using the only known organometallic linker [(η 4 -benzoquinone)Mn(CO) 3 ][Na].8 However, none of these polymers contained silver cations. Thus, our 1-D polymers 2a,b are the first coordination polymers with the neutral ...
Most of these examples reported so far involve coordination assemblies, where this kind of noncov... more Most of these examples reported so far involve coordination assemblies, where this kind of noncovalent interaction occurs between the electron-deficient aromatic rings of the coordinated ligands and the counteranions of the assemblies.57 However, we also note the existence of some ...
Steady-state irradiation under visible light of a covalent Ir(III)-photosensitized polyoxotungsta... more Steady-state irradiation under visible light of a covalent Ir(III)-photosensitized polyoxotungstate is reported. In the presence of a sacrificial electron donor, the photolysis leads to the very efficient photoreduction of the polyoxometalate. Successive formation of the one-electron and two-electron reduced species, which are unambiguously identified by comparison with spectroelectrochemical measurements, is observed with a significantly faster rate reaction for the formation of the oneelectron reduced species. The kinetics of the photoreduction, which are correlated to the reduction potentials of the polyoxometalate (POM), can be finely tuned by the presence of an acid. Indeed light-driven formation of the two-electron reduced POM is considerably facilitated in the presence of acetic acid. The system is also able to perform photocatalytic hydrogen production under visible light without significant loss of performance over more than 1 week of continuous photolysis and displays higher photocatalytic efficiency than the related multi-component system, outlining the decisive effect of the covalent bonding between the POM and the photosensitizer. This functional and modular system constitutes a promising step for the development of charge photoaccumulation devices and subsequent photoelectrocatalysts for artificial photosynthesis. Photoconversion of light into chemical fuels is emerging as a major scientific challenge. 1-4 In the past decades, molecular approaches have mostly focused on one hand on the design of photosensitive systems displaying long-lived photo-induced charge separation states to permit further electron transfers 5-10 and, on the other hand, on catalysts able to use these photogenerated charges for achieving either oxygen 11-18 or hydrogen evolution. 19-24 As these two reactions are multi-electronic processes while photosensitizers deliver electrons and holes sequentially, the charges need to be directed to a charge accumulation site. 25 However, only a few molecular photoactive systems with a designed charge accumulation site have been described so far. 26-30 Another requirement is crucial for efficient charge accumulation in such systems: when partially filled, the reservoir should not interfere with the photoactive moiety. Indeed, in classical donor-acceptor (D-A) systems, the electron acceptor, once reduced, potentially becomes an electron donor and often displays lightabsorbing properties. Thus it may act, in a subsequent light-driven process, as a deleterious
The first luminescent platinum(ii) complex bearing phosphinine co-ligands with a long-lived emiss... more The first luminescent platinum(ii) complex bearing phosphinine co-ligands with a long-lived emission from a phosphinine-localised triplet excited state is reported.
Unlike p-dithiobenzoquinone (), which is extremely reactive and has never been isolated, the meta... more Unlike p-dithiobenzoquinone (), which is extremely reactive and has never been isolated, the metal-stabilised p-dithiobenzoquinone [Cp*Ir(eta4-C6H4S2)] () was prepared and used as an efficient organometallic linker to construct novel supramolecular assemblies. Treatment of with the electrophilic Pt(II)(terpy) building blocks produced the supramolecular assembly {[Pt(terpy){Cp*Ir-p-(eta4-C6H4S2)}Pt(terpy)][OTf]4}n (), which was fully characterised and its molecular structure was determined by X-ray crystallography. The structure of revealed the presence of pi-pi and Pt[dot dot dot]Pt interactions among individual molecules describing a 1D chain. Complex showed unusual UV/Vis absorption and luminescence behaviour at low temperature, imparted from self-aggregation mediated by pi-pi and Pt...Pt interactions.
Electron-deficient arenes are now recognized as potent anion receptors, mainly through the establ... more Electron-deficient arenes are now recognized as potent anion receptors, mainly through the establishment of π-anion interactions. Cyclopentadienyl ligands (Cp's) also belong to the family of arenes that exhibit very low electron density at their centroid due to the presence of the ...
The chiral octahedral bimetallic assemblies [(bpy) 2 Ru(o-L Ir)][CF 3 SO 3 ] 2 (2), [(ppy) 2 Rh(o... more The chiral octahedral bimetallic assemblies [(bpy) 2 Ru(o-L Ir)][CF 3 SO 3 ] 2 (2), [(ppy) 2 Rh(o-L Ir)][NO 3 ] (7) and [(ppy) 2 Ir(o-L Ir)][NO 3 ] (8) featuring chelating organometallic linker [Cp*Ir(h 4-o-benzoquinone)] (o-L Ir) have been prepared and fully characterized. Anion metathesis following a convenient procedure allowed the preparation of the related diastereomers [D-(bpy) 2 Ru(o-L Ir)][D-TRISPHAT] 2 (2a) and [L-(bpy) 2 Ru (o-L Ir)][D-TRISPHAT] 2 (2b) as well as the octahedral rhodium [(D, L)-(ppy) 2 Rh (o-L Ir)][D-TRISPHAT] (7a, 7b) and iridium [(D, L)-(ppy) 2 Ir(o-L Ir)][D-TRISPHAT] (8a, 8b) bimetallic assemblies. 1 H NMR studies in solution carried out on these compounds showed different behavior. For instance, the rhodium and iridium compounds exhibited weak chiral recognition in contrast the ruthenium compounds allowed facile differentiation between the two diastereomers suggesting that chiral recognition occurs between the enantiopure anion and the cationic part of the molecule.
Uploads
Papers by Jamal Moussa