ABSTRACT Phosphinimines, R3P=NSiMe3, undergo hydrolysis to form the phosphiniminium cation, R3P=N... more ABSTRACT Phosphinimines, R3P=NSiMe3, undergo hydrolysis to form the phosphiniminium cation, R3P=NH2+, which forms the ion pair [R3P=NH2+][X-] in the presence of an anion. Preliminary studies show that in the presence of TcO4-, Ph3P=NSiMe3 forms [Ph3P=NH2+][TcO4-] and [Ph3P=NH2+] is selective for TcO4- over other anions. Technetium-99 is present as environmental contamination in the form of 99TcO4-, which is extremely mobile. Currently available methods to measure this contamination are time consuming and tedious. A method to preconcentrate and measure 99Tc environmental contamination in a quick and efficient manner is needed. The selectivity of the phosphiniminium cation for TcO4- may make phosphinimines suitable for such preconcentration and possibly for measurement. Several phosphinimines were synthesized and characterized for their stability and selectivity with 99TcO4-, including Ph3P=NSiMe3, (9-anthracenyl)Ph2P=NSiMe3, (1-napthyl)Ph2P=NSiMe3, and (p-COOMe)C6H4Ph2P=NSiMe3. (9-anthracenyl)Ph2P=NSiMe3 and (1-napthyl)Ph2P=NSiMe3 include possible reporter groups and (p-COOMe)C6H4Ph2P=NSiMe3 contains a linking moiety for incorporating reporter groups or attaching the phosphinimine to a polymer support.
The design and synthesis of a new dipyridyl ligand with appended phenanthryl moieties is describe... more The design and synthesis of a new dipyridyl ligand with appended phenanthryl moieties is described. On addition of increments of silver(I) trifluoromethanesulfonate to a solution of the ligand, the phenanthryl protons shift upfield in the (1)H NMR spectrum, suggesting that the phenanthrenes pi-stack on coordination of silver(I). In accord with this, the oxidation potential decreased from 1.74 to 1.55 V on complexation of silver(I). The pi-stacking was confirmed with the single-crystal X-ray structure of a palladium(II) coordination complex.
Journal of the American Chemical Society, Jul 1, 2003
Phosphorus functionalized trimeric alanine compounds (l)- and (d)-P(CH(2)NHCH(CH(3))COOH)(3) 2 ar... more Phosphorus functionalized trimeric alanine compounds (l)- and (d)-P(CH(2)NHCH(CH(3))COOH)(3) 2 are prepared in 90% yields by the Mannich reaction of Tris(hydroxymethyl)phosphine 1 with (l)- or (d)- Alanine in aqueous media. The hydration properties of (l)-2 and (d)-2 in water and water-methanol mixtures are described. The crystal structure analysis of (l)-2.4H(2)O, reveals that the alanine molecules pack to form two-dimensional bilayers running parallel to (001). The layered structural motif depicts two closely packed monolayers of 2 each oriented with its phosphorus atoms projected at the center of the bilayer and adjacent monolayers are held together by hydrogen bonds between amine and carboxylate groups. The water bilayers are juxtaposed with the H-bonded alanine trimers leading to 18-membered (H(2)O)(18) water rings. Exposure of aqueous solution of (l)-2 and (d)-2 to methanol vapors resulted in closely packed (l)-2 and (d)-2 solvated with mixed water-methanol (H(2)O)(15)(CH(3)OH)(3) clusters. The O-O distances in the mixed methanol-water clusters of (l)-2.3H(2)O.CH(3)OH and (d)-2.3H(2)O.CH(3)OH (O-O(average) = 2.857 A) are nearly identical to the O-O distance observed in the supramolecular (H(2)O)(18) water structure (O-O(average) = 2.859 A) implying the retention of the hydrogen bonded structure in water despite the accommodation of hydrophobic methanol groups within the supramolecular (H(2)O)(15)(CH(3)OH)(3) framework. The O-O distances in (l)-2.3H(2)O.CH(3)OH and (d)-2.3H(2)O.CH(3)OH and in (H(2)O)(18) are very close to the O-O distance reported for liquid water (2.85 A).
Journal of the Chemical Society, Perkin Transactions 2, 1995
ABSTRACT The asymmetrical E,E-configured para-disubstituted 4-methoxyacetophenone azines with 4′-... more ABSTRACT The asymmetrical E,E-configured para-disubstituted 4-methoxyacetophenone azines with 4′-bromo-(1), 4′cyano-(2) and 4′-nitro-(3) substituents have been synthesized and their crystal structures have been determined. The synergetic reinforcement of ‘push’ and ‘pull’ effects does not suffice to overcome the intrinsic or packing induced N–N gauche preference, and azines 1–3 all assume distinctly gauche N–N conformations (dihedral angle of 115–140°). The crystal packing is characterized by offset T-shaped and parallel displaced face-to-face arene-arene contacts between pairs of azines with parallel or anti-parallel D→A orientations. This crystal architecture results in a net dipole of crystals of 1. The structural data are analysed in comparison with the symmetrical E,E-configured para-disubstituted acetophenone azines 4–7. With regard to this best possible reference data set, the structural parameters of 1–3 do not show any significant manifestation of special electronic interactions over the N-perturbed extended π-system to be associated with the asymmetry of the azines. While there exists no structural evidence of conjugation in these solid state structures, our results do not rule out asymmetry effects on the electronic structure of the ground or the excited states.
Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 2005
Asymmetric Re(V) oxo complexes of the type cis‐[ReO(Y)(acac2en/pn)] (Y = CN, NCS) were generated ... more Asymmetric Re(V) oxo complexes of the type cis‐[ReO(Y)(acac2en/pn)] (Y = CN, NCS) were generated from the symmetric precursors trans‐[ReO(X)(acac2en/pn)] (X = H2O, Cl) by reaction with cyanide and thiocyanate. The products were characterized using standard spectroscopic methods, elemental analyses and single crystal X‐ray diffraction. The crystallographic data for the structures reported are as follows: cis‐[ReO(NCS)(acac2pn)] (H20C14N3O3SRe), 1, monoclinic (P21/n), a = 8.0047(6) Å, b = 13.6118(10) Å, c = 30.597(2)
3. ChemInform Abstract ChemInform is a weekly Abstracting Service, delivering concise information... more 3. ChemInform Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full ...
The reaction of the chiral acetal 4 with furan and cyclopentadiene in the presence ~ff a Lewis ac... more The reaction of the chiral acetal 4 with furan and cyclopentadiene in the presence ~ff a Lewis acid gives 4+3 cycloadducts in very good yields. Diastereoselectivity in the case of furan is exceptionally high, while that for the reaction with cyclopenladiene is lower. The sense of diastereoseleclion in the case of furan is opposite to that which would be predicted on the basis of mechanistic models for the origin of stereoselectivity in many reactions of chiral acetals mediated by Lewis acids.
Phosphorus, Sulfur, and Silicon and the Related Elements, 2002
Unnatural or modified amino acids have become important biochemical vectors because of their pote... more Unnatural or modified amino acids have become important biochemical vectors because of their potential utility in diagnostic or therapeutic medicine. Our ongoing research in hydroxymethyl phosphine chemistry has provided unique reaction pathways to produce unnatural ...
Introduction: Tetradentate acyclic and macrocyclic diphosphine ligands (P 2 N 2 and P 2 S 2) have... more Introduction: Tetradentate acyclic and macrocyclic diphosphine ligands (P 2 N 2 and P 2 S 2) have been synthesized and characterized as potential chelates for Rh(III). Methods: The coordination complexes [RhCl 2 (L1)]Cl, trans-[RhCl 2 (L2)]PF 6 , [Ni(L2)](PF 6) 2 , [Ni(L3)](PF 6) 2 , [RhCl 2 (L4)]PF 6 and [RhCl 2 (L5)]PF 6 have been synthesized and characterized. In addition, radiochemistry studies of the 105 Rh complexes with the ligands N,N′-bis[2-(diphenylphosphino)phenyl]-1,3-diaminopropane (L1), 4,8-diphenyl-1,11-diaza-4,8-diphosphaundecane (L2), 5,9-diphenyl-5,9-diphospha-2,12-dithiatridecane (L3) and 1,4,8,11-tetraphenyl-4,8-diphospha-1,11-dithiaundecane (L4) are reported, including normal mouse biodistributions of 105 Rh-L2. Results: trans-[RhCl 2 (L2)]PF 6 crystallized in the monoclinic space group P2 1 /c with a=9.9353(5) Å, b=9.0929(5) Å, c=28.689(1) Å, β=93.1400(10) deg, Z=4, R=0.037 and R w =0.053. [Ni(L2)](PF 6) 2 crystallized in the monoclinic space group P2 1 /c with a=11.9665(6) Å, b=14.8903(7) Å, c=31.148(1) Å, β=91.587(1) deg, Z=8, R=0.056 and R w =0.083. μ-O 2 SO 2-[Ni(L5)] 2 (PF 6) 2 , an unusual sulfate-bridged Ni (II) dimer, crystallized in the triclinic space group P1 bar with a=15.179(2) Å, b=15.514(2) Å, c=16.128(2) Å, α=105.280(7) deg, β=113.074(6) deg, γ=101.657(8) deg, Z=2, R=0.050 and R w =0.072. Conclusions: Phosphine-containing ligands allowed for lower temperatures and lower ethanol concentrations in the formulations for 105 Rh (L) complexation, but at the expense of higher ligand concentrations.
Introduction: A variety of (bis)thiosemicarbazone-based ligand systems have been investigated as ... more Introduction: A variety of (bis)thiosemicarbazone-based ligand systems have been investigated as chelating agents for Au(III) complexes with potential radiotherapeutic applications. Ligand systems containing an ethyl, propyl or butyl backbone between the two imine N donors have been synthesized to evaluate chelate ring size effects on the resultant Au(III) complex stability at the macroscopic and radiotracer levels. Methods: The Au(III) complexes were synthesized and characterized by NMR, electrospray ionization mass spectra, elemental analysis and X-ray crystallography. The 198 Au complexes were evaluated in vitro at the tracer level for stability in phosphate-buffered saline at pH 7.4 and 37°C. One of these complexes [ 198 Au(3,4-HxTSE)] showed high in vitro stability and was further evaluated in vivo in normal mice. Results: [Au(ATSM)]AuCl 4 •2CH 3 OH, (ATSM=diacetyl-bis(N 4-methylthiosemicarbazone)) H 14 C 8 N 6 O 2 S 2 Cl 4 Au 2 •2CH 3 OH, crystallized from methanol in the monoclinic space group P21/n with a=14.7293(13) Å, b=7.7432(7) Å, c=20.4363(18) Å, β=100.140(2)°, V=2294.4 (4) Å 3 , Z=4; [Au(3,4-HxTSE)]Cl•CH 3 CH 2 OH/AuCl 2 , (3,4-HxTSE=3,4-hexanedione-bis(N 4-ethylthiosemicarbazone)) H 26 C 13.6 N 6 O 0.8 S 2 Cl 1.2 Au 1.2 , crystallized from ethanol in the monoclinic space group P21/c with a=10.1990(10) Å, b=13.8833(14) Å, c=15.1752(15) Å, β=99.353(2)°, V=2120.2 (4) Å 3 , Z=4. Conclusions: These studies revealed poor stability of the [ 198 Au][Au(3,4-HxTSE)] + complex; however, crystal structure data suggest potential alterations to the ligand backbone may increase stability.
... Jonathan W. Steed,*,+ Carl P. Johnson: Charles L. Barnes: Ravindra K. Juneja: Jerry L. Atwood... more ... Jonathan W. Steed,*,+ Carl P. Johnson: Charles L. Barnes: Ravindra K. Juneja: Jerry L. Atwood,*?$ Sean Reilly: Rebecca L. Hollis: Paul H. Smith: and David L ... Data sets were corrected'for Lorentz and polarization effects, absorption (pscans) and crystal decay where appropriate ...
Design and synthesis of chelating bisphosphines functionalized with the smallest chemical unit &a... more Design and synthesis of chelating bisphosphines functionalized with the smallest chemical unit "H" on the P(III) centers ((PH(2)CH(2))(2)CHCH(2)NHPh (4) and (PH(2)CH(2))(2)CHCONHPh (5)) are described. Studies demonstrating that no bulky chemical substituents are necessary to offer thermal/oxidative stability to the -PH(2) groups in 4 and 5 are described. The H atoms around the P(III) centers in 5 (or 4) concur limited/no steric influence, but yet the phosphines manifest high nucleophilicity to coordinate strongly with W(0) and Re(I). The studies include synthesis and X-ray structural characterization of an air-stable primary bisphosphine (5) and its transition-metal chemistry with W(CO)(6) and Re(CO)(5)Br to produce the complexes (eta(2)-(PH(2)CH(2))(2)CHCONHPh)W(CO)(4) (6) and (eta(2)-(PH(2)CH(2))(2)CHCONHPh)Re(CO)(3)Br (7), respectively.
Phosphorus functionalized trimeric alanine compounds (l)- and (d)-P(CH(2)NHCH(CH(3))COOH)(3) 2 ar... more Phosphorus functionalized trimeric alanine compounds (l)- and (d)-P(CH(2)NHCH(CH(3))COOH)(3) 2 are prepared in 90% yields by the Mannich reaction of Tris(hydroxymethyl)phosphine 1 with (l)- or (d)- Alanine in aqueous media. The hydration properties of (l)-2 and (d)-2 in water and water-methanol mixtures are described. The crystal structure analysis of (l)-2.4H(2)O, reveals that the alanine molecules pack to form two-dimensional bilayers running parallel to (001). The layered structural motif depicts two closely packed monolayers of 2 each oriented with its phosphorus atoms projected at the center of the bilayer and adjacent monolayers are held together by hydrogen bonds between amine and carboxylate groups. The water bilayers are juxtaposed with the H-bonded alanine trimers leading to 18-membered (H(2)O)(18) water rings. Exposure of aqueous solution of (l)-2 and (d)-2 to methanol vapors resulted in closely packed (l)-2 and (d)-2 solvated with mixed water-methanol (H(2)O)(15)(CH(3)OH)(3) clusters. The O-O distances in the mixed methanol-water clusters of (l)-2.3H(2)O.CH(3)OH and (d)-2.3H(2)O.CH(3)OH (O-O(average) = 2.857 A) are nearly identical to the O-O distance observed in the supramolecular (H(2)O)(18) water structure (O-O(average) = 2.859 A) implying the retention of the hydrogen bonded structure in water despite the accommodation of hydrophobic methanol groups within the supramolecular (H(2)O)(15)(CH(3)OH)(3) framework. The O-O distances in (l)-2.3H(2)O.CH(3)OH and (d)-2.3H(2)O.CH(3)OH and in (H(2)O)(18) are very close to the O-O distance reported for liquid water (2.85 A).
The design and synthesis of a new dipyridyl ligand with appended phenanthryl moieties is describe... more The design and synthesis of a new dipyridyl ligand with appended phenanthryl moieties is described. On addition of increments of silver(I) trifluoromethanesulfonate to a solution of the ligand, the phenanthryl protons shift upfield in the (1)H NMR spectrum, suggesting that the phenanthrenes pi-stack on coordination of silver(I). In accord with this, the oxidation potential decreased from 1.74 to 1.55 V on complexation of silver(I). The pi-stacking was confirmed with the single-crystal X-ray structure of a palladium(II) coordination complex.
ABSTRACT Phosphinimines, R3P=NSiMe3, undergo hydrolysis to form the phosphiniminium cation, R3P=N... more ABSTRACT Phosphinimines, R3P=NSiMe3, undergo hydrolysis to form the phosphiniminium cation, R3P=NH2+, which forms the ion pair [R3P=NH2+][X-] in the presence of an anion. Preliminary studies show that in the presence of TcO4-, Ph3P=NSiMe3 forms [Ph3P=NH2+][TcO4-] and [Ph3P=NH2+] is selective for TcO4- over other anions. Technetium-99 is present as environmental contamination in the form of 99TcO4-, which is extremely mobile. Currently available methods to measure this contamination are time consuming and tedious. A method to preconcentrate and measure 99Tc environmental contamination in a quick and efficient manner is needed. The selectivity of the phosphiniminium cation for TcO4- may make phosphinimines suitable for such preconcentration and possibly for measurement. Several phosphinimines were synthesized and characterized for their stability and selectivity with 99TcO4-, including Ph3P=NSiMe3, (9-anthracenyl)Ph2P=NSiMe3, (1-napthyl)Ph2P=NSiMe3, and (p-COOMe)C6H4Ph2P=NSiMe3. (9-anthracenyl)Ph2P=NSiMe3 and (1-napthyl)Ph2P=NSiMe3 include possible reporter groups and (p-COOMe)C6H4Ph2P=NSiMe3 contains a linking moiety for incorporating reporter groups or attaching the phosphinimine to a polymer support.
The design and synthesis of a new dipyridyl ligand with appended phenanthryl moieties is describe... more The design and synthesis of a new dipyridyl ligand with appended phenanthryl moieties is described. On addition of increments of silver(I) trifluoromethanesulfonate to a solution of the ligand, the phenanthryl protons shift upfield in the (1)H NMR spectrum, suggesting that the phenanthrenes pi-stack on coordination of silver(I). In accord with this, the oxidation potential decreased from 1.74 to 1.55 V on complexation of silver(I). The pi-stacking was confirmed with the single-crystal X-ray structure of a palladium(II) coordination complex.
Journal of the American Chemical Society, Jul 1, 2003
Phosphorus functionalized trimeric alanine compounds (l)- and (d)-P(CH(2)NHCH(CH(3))COOH)(3) 2 ar... more Phosphorus functionalized trimeric alanine compounds (l)- and (d)-P(CH(2)NHCH(CH(3))COOH)(3) 2 are prepared in 90% yields by the Mannich reaction of Tris(hydroxymethyl)phosphine 1 with (l)- or (d)- Alanine in aqueous media. The hydration properties of (l)-2 and (d)-2 in water and water-methanol mixtures are described. The crystal structure analysis of (l)-2.4H(2)O, reveals that the alanine molecules pack to form two-dimensional bilayers running parallel to (001). The layered structural motif depicts two closely packed monolayers of 2 each oriented with its phosphorus atoms projected at the center of the bilayer and adjacent monolayers are held together by hydrogen bonds between amine and carboxylate groups. The water bilayers are juxtaposed with the H-bonded alanine trimers leading to 18-membered (H(2)O)(18) water rings. Exposure of aqueous solution of (l)-2 and (d)-2 to methanol vapors resulted in closely packed (l)-2 and (d)-2 solvated with mixed water-methanol (H(2)O)(15)(CH(3)OH)(3) clusters. The O-O distances in the mixed methanol-water clusters of (l)-2.3H(2)O.CH(3)OH and (d)-2.3H(2)O.CH(3)OH (O-O(average) = 2.857 A) are nearly identical to the O-O distance observed in the supramolecular (H(2)O)(18) water structure (O-O(average) = 2.859 A) implying the retention of the hydrogen bonded structure in water despite the accommodation of hydrophobic methanol groups within the supramolecular (H(2)O)(15)(CH(3)OH)(3) framework. The O-O distances in (l)-2.3H(2)O.CH(3)OH and (d)-2.3H(2)O.CH(3)OH and in (H(2)O)(18) are very close to the O-O distance reported for liquid water (2.85 A).
Journal of the Chemical Society, Perkin Transactions 2, 1995
ABSTRACT The asymmetrical E,E-configured para-disubstituted 4-methoxyacetophenone azines with 4′-... more ABSTRACT The asymmetrical E,E-configured para-disubstituted 4-methoxyacetophenone azines with 4′-bromo-(1), 4′cyano-(2) and 4′-nitro-(3) substituents have been synthesized and their crystal structures have been determined. The synergetic reinforcement of ‘push’ and ‘pull’ effects does not suffice to overcome the intrinsic or packing induced N–N gauche preference, and azines 1–3 all assume distinctly gauche N–N conformations (dihedral angle of 115–140°). The crystal packing is characterized by offset T-shaped and parallel displaced face-to-face arene-arene contacts between pairs of azines with parallel or anti-parallel D→A orientations. This crystal architecture results in a net dipole of crystals of 1. The structural data are analysed in comparison with the symmetrical E,E-configured para-disubstituted acetophenone azines 4–7. With regard to this best possible reference data set, the structural parameters of 1–3 do not show any significant manifestation of special electronic interactions over the N-perturbed extended π-system to be associated with the asymmetry of the azines. While there exists no structural evidence of conjugation in these solid state structures, our results do not rule out asymmetry effects on the electronic structure of the ground or the excited states.
Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 2005
Asymmetric Re(V) oxo complexes of the type cis‐[ReO(Y)(acac2en/pn)] (Y = CN, NCS) were generated ... more Asymmetric Re(V) oxo complexes of the type cis‐[ReO(Y)(acac2en/pn)] (Y = CN, NCS) were generated from the symmetric precursors trans‐[ReO(X)(acac2en/pn)] (X = H2O, Cl) by reaction with cyanide and thiocyanate. The products were characterized using standard spectroscopic methods, elemental analyses and single crystal X‐ray diffraction. The crystallographic data for the structures reported are as follows: cis‐[ReO(NCS)(acac2pn)] (H20C14N3O3SRe), 1, monoclinic (P21/n), a = 8.0047(6) Å, b = 13.6118(10) Å, c = 30.597(2)
3. ChemInform Abstract ChemInform is a weekly Abstracting Service, delivering concise information... more 3. ChemInform Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full ...
The reaction of the chiral acetal 4 with furan and cyclopentadiene in the presence ~ff a Lewis ac... more The reaction of the chiral acetal 4 with furan and cyclopentadiene in the presence ~ff a Lewis acid gives 4+3 cycloadducts in very good yields. Diastereoselectivity in the case of furan is exceptionally high, while that for the reaction with cyclopenladiene is lower. The sense of diastereoseleclion in the case of furan is opposite to that which would be predicted on the basis of mechanistic models for the origin of stereoselectivity in many reactions of chiral acetals mediated by Lewis acids.
Phosphorus, Sulfur, and Silicon and the Related Elements, 2002
Unnatural or modified amino acids have become important biochemical vectors because of their pote... more Unnatural or modified amino acids have become important biochemical vectors because of their potential utility in diagnostic or therapeutic medicine. Our ongoing research in hydroxymethyl phosphine chemistry has provided unique reaction pathways to produce unnatural ...
Introduction: Tetradentate acyclic and macrocyclic diphosphine ligands (P 2 N 2 and P 2 S 2) have... more Introduction: Tetradentate acyclic and macrocyclic diphosphine ligands (P 2 N 2 and P 2 S 2) have been synthesized and characterized as potential chelates for Rh(III). Methods: The coordination complexes [RhCl 2 (L1)]Cl, trans-[RhCl 2 (L2)]PF 6 , [Ni(L2)](PF 6) 2 , [Ni(L3)](PF 6) 2 , [RhCl 2 (L4)]PF 6 and [RhCl 2 (L5)]PF 6 have been synthesized and characterized. In addition, radiochemistry studies of the 105 Rh complexes with the ligands N,N′-bis[2-(diphenylphosphino)phenyl]-1,3-diaminopropane (L1), 4,8-diphenyl-1,11-diaza-4,8-diphosphaundecane (L2), 5,9-diphenyl-5,9-diphospha-2,12-dithiatridecane (L3) and 1,4,8,11-tetraphenyl-4,8-diphospha-1,11-dithiaundecane (L4) are reported, including normal mouse biodistributions of 105 Rh-L2. Results: trans-[RhCl 2 (L2)]PF 6 crystallized in the monoclinic space group P2 1 /c with a=9.9353(5) Å, b=9.0929(5) Å, c=28.689(1) Å, β=93.1400(10) deg, Z=4, R=0.037 and R w =0.053. [Ni(L2)](PF 6) 2 crystallized in the monoclinic space group P2 1 /c with a=11.9665(6) Å, b=14.8903(7) Å, c=31.148(1) Å, β=91.587(1) deg, Z=8, R=0.056 and R w =0.083. μ-O 2 SO 2-[Ni(L5)] 2 (PF 6) 2 , an unusual sulfate-bridged Ni (II) dimer, crystallized in the triclinic space group P1 bar with a=15.179(2) Å, b=15.514(2) Å, c=16.128(2) Å, α=105.280(7) deg, β=113.074(6) deg, γ=101.657(8) deg, Z=2, R=0.050 and R w =0.072. Conclusions: Phosphine-containing ligands allowed for lower temperatures and lower ethanol concentrations in the formulations for 105 Rh (L) complexation, but at the expense of higher ligand concentrations.
Introduction: A variety of (bis)thiosemicarbazone-based ligand systems have been investigated as ... more Introduction: A variety of (bis)thiosemicarbazone-based ligand systems have been investigated as chelating agents for Au(III) complexes with potential radiotherapeutic applications. Ligand systems containing an ethyl, propyl or butyl backbone between the two imine N donors have been synthesized to evaluate chelate ring size effects on the resultant Au(III) complex stability at the macroscopic and radiotracer levels. Methods: The Au(III) complexes were synthesized and characterized by NMR, electrospray ionization mass spectra, elemental analysis and X-ray crystallography. The 198 Au complexes were evaluated in vitro at the tracer level for stability in phosphate-buffered saline at pH 7.4 and 37°C. One of these complexes [ 198 Au(3,4-HxTSE)] showed high in vitro stability and was further evaluated in vivo in normal mice. Results: [Au(ATSM)]AuCl 4 •2CH 3 OH, (ATSM=diacetyl-bis(N 4-methylthiosemicarbazone)) H 14 C 8 N 6 O 2 S 2 Cl 4 Au 2 •2CH 3 OH, crystallized from methanol in the monoclinic space group P21/n with a=14.7293(13) Å, b=7.7432(7) Å, c=20.4363(18) Å, β=100.140(2)°, V=2294.4 (4) Å 3 , Z=4; [Au(3,4-HxTSE)]Cl•CH 3 CH 2 OH/AuCl 2 , (3,4-HxTSE=3,4-hexanedione-bis(N 4-ethylthiosemicarbazone)) H 26 C 13.6 N 6 O 0.8 S 2 Cl 1.2 Au 1.2 , crystallized from ethanol in the monoclinic space group P21/c with a=10.1990(10) Å, b=13.8833(14) Å, c=15.1752(15) Å, β=99.353(2)°, V=2120.2 (4) Å 3 , Z=4. Conclusions: These studies revealed poor stability of the [ 198 Au][Au(3,4-HxTSE)] + complex; however, crystal structure data suggest potential alterations to the ligand backbone may increase stability.
... Jonathan W. Steed,*,+ Carl P. Johnson: Charles L. Barnes: Ravindra K. Juneja: Jerry L. Atwood... more ... Jonathan W. Steed,*,+ Carl P. Johnson: Charles L. Barnes: Ravindra K. Juneja: Jerry L. Atwood,*?$ Sean Reilly: Rebecca L. Hollis: Paul H. Smith: and David L ... Data sets were corrected'for Lorentz and polarization effects, absorption (pscans) and crystal decay where appropriate ...
Design and synthesis of chelating bisphosphines functionalized with the smallest chemical unit &a... more Design and synthesis of chelating bisphosphines functionalized with the smallest chemical unit "H" on the P(III) centers ((PH(2)CH(2))(2)CHCH(2)NHPh (4) and (PH(2)CH(2))(2)CHCONHPh (5)) are described. Studies demonstrating that no bulky chemical substituents are necessary to offer thermal/oxidative stability to the -PH(2) groups in 4 and 5 are described. The H atoms around the P(III) centers in 5 (or 4) concur limited/no steric influence, but yet the phosphines manifest high nucleophilicity to coordinate strongly with W(0) and Re(I). The studies include synthesis and X-ray structural characterization of an air-stable primary bisphosphine (5) and its transition-metal chemistry with W(CO)(6) and Re(CO)(5)Br to produce the complexes (eta(2)-(PH(2)CH(2))(2)CHCONHPh)W(CO)(4) (6) and (eta(2)-(PH(2)CH(2))(2)CHCONHPh)Re(CO)(3)Br (7), respectively.
Phosphorus functionalized trimeric alanine compounds (l)- and (d)-P(CH(2)NHCH(CH(3))COOH)(3) 2 ar... more Phosphorus functionalized trimeric alanine compounds (l)- and (d)-P(CH(2)NHCH(CH(3))COOH)(3) 2 are prepared in 90% yields by the Mannich reaction of Tris(hydroxymethyl)phosphine 1 with (l)- or (d)- Alanine in aqueous media. The hydration properties of (l)-2 and (d)-2 in water and water-methanol mixtures are described. The crystal structure analysis of (l)-2.4H(2)O, reveals that the alanine molecules pack to form two-dimensional bilayers running parallel to (001). The layered structural motif depicts two closely packed monolayers of 2 each oriented with its phosphorus atoms projected at the center of the bilayer and adjacent monolayers are held together by hydrogen bonds between amine and carboxylate groups. The water bilayers are juxtaposed with the H-bonded alanine trimers leading to 18-membered (H(2)O)(18) water rings. Exposure of aqueous solution of (l)-2 and (d)-2 to methanol vapors resulted in closely packed (l)-2 and (d)-2 solvated with mixed water-methanol (H(2)O)(15)(CH(3)OH)(3) clusters. The O-O distances in the mixed methanol-water clusters of (l)-2.3H(2)O.CH(3)OH and (d)-2.3H(2)O.CH(3)OH (O-O(average) = 2.857 A) are nearly identical to the O-O distance observed in the supramolecular (H(2)O)(18) water structure (O-O(average) = 2.859 A) implying the retention of the hydrogen bonded structure in water despite the accommodation of hydrophobic methanol groups within the supramolecular (H(2)O)(15)(CH(3)OH)(3) framework. The O-O distances in (l)-2.3H(2)O.CH(3)OH and (d)-2.3H(2)O.CH(3)OH and in (H(2)O)(18) are very close to the O-O distance reported for liquid water (2.85 A).
The design and synthesis of a new dipyridyl ligand with appended phenanthryl moieties is describe... more The design and synthesis of a new dipyridyl ligand with appended phenanthryl moieties is described. On addition of increments of silver(I) trifluoromethanesulfonate to a solution of the ligand, the phenanthryl protons shift upfield in the (1)H NMR spectrum, suggesting that the phenanthrenes pi-stack on coordination of silver(I). In accord with this, the oxidation potential decreased from 1.74 to 1.55 V on complexation of silver(I). The pi-stacking was confirmed with the single-crystal X-ray structure of a palladium(II) coordination complex.
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