Papers by Ahmed Emadeldeen Abdellatif Mohamed
Inorganics, 2013
The synthesis of diazonium tetrachloroaurate(III) complexes [R-4-C 6 H 4 N≡N]AuCl 4 involves prot... more The synthesis of diazonium tetrachloroaurate(III) complexes [R-4-C 6 H 4 N≡N]AuCl 4 involves protonation of anilines CN-4-C 6 H 4 NH 2 , C 8 F 17-4-C 6 H 4 NH 2 , and C 6 H 13-4-C 6 H 4 NH 2 with tetrachloroauric acid H[AuCl 4 ] 3H 2 O in acetonitrile followed by one-electron oxidation using [NO]PF 6. FT-IR shows the diazonium stretching frequency at 2277 cm −1 (CN), 2305 cm −1 (C 8 F 17), and 2253 cm −1 (C 6 H 13). Thermogravimetric Analysis (TGA) shows the high stabilities of the electron-withdrawing substituents C 8 F 17 and CN compared with the electron-donating substituent C 6 H 13. Residual Gas Analysis (RGA) shows the release of molecular nitrogen as the main gas residue among other small molecular weight chlorinated hydrocarbons and chlorobenzene. Temperature-Dependent X-Ray Powder Diffraction (TD-XRD) shows the thermal decomposition in C 6 H 13 diffraction patterns at low temperature of 80 °C which supports the TGA and RGA (TGA-MS) conclusions. X-ray structure shows N≡N bond distance of approximately 1.10 Å and N≡N-C bond angle of 178°.
Inorganica Chimica Acta, 2003
The trigonal planar Au(I) complex Cs 8 [Au(TPPTS) 3 ]×/5.25H 2 O, TPPTS 0/tris-sulfonatophenyl ph... more The trigonal planar Au(I) complex Cs 8 [Au(TPPTS) 3 ]×/5.25H 2 O, TPPTS 0/tris-sulfonatophenyl phosphine, has been structurally characterized. The X-ray data for the triclinic crystal, P1; are a 0/13.7003(4) Å , b 0/18.0001(6) Å , c 0/18.2817(2) Å , a 0/100.249(2)8, b 0/99.593(2)8, g 0/109.818(2)8, V0/4046.3(2) Å 3 , Z0/2. The complex has Au Ã/P distances of 2.374(6), 2.394(5), and 2.417(5) Å. A network of bonding has been found involving the Cs ' ions, the sulfonate groups of the ligands, and the H 2 O solvent molecules. Luminescence studies of [Au(TPPTS) 3 ] 8(and (TPA) 3 AuCl, TPA 0/1,3,5-triaza-7-phosphaadamantane, in the solid state and in solution are discussed and quenching studies of the luminescence of [Au(TPPTS) 3 ] 8(are reported with alkyl halides and oxygen.
Inorganica Chimica Acta, 2004
The mono-and dinuclear base-stabilized gold(I) pyrazolate complexes, (PPh 3)Au(l-3,5-Ph 2 pz)) (1... more The mono-and dinuclear base-stabilized gold(I) pyrazolate complexes, (PPh 3)Au(l-3,5-Ph 2 pz)) (1), (TPA)Au(3,5-Ph 2 pz), TPA ¼ 1,3,5-triaza-7-phophaadamantane (2), [(PPh 3) 2 Au(l-3,5-Ph 2 pz)]NO 3 (3) and [(dppp)Au(l-3,5-Ph 2 pz)]NO 3 , dppp ¼ bis-(diphenylphosphino)propane (4), have been synthesized and structurally characterized. The mononuclear gold(I) complexes 1 and 2 show intermolecular AuÁ Á ÁAu interactions of 3.1540(6) and 3.092(6) A, while the dinuclear gold(I) complexes 3 and 4 show an intramolecular AuÁ Á ÁAu distances of 3.3519(7) and 3.109(2) A, respectively, typical of an aurophilic attraction. Complexes 1-4 exhibit luminescence at 77 K when excited with ca. 333 nm UV light with an emission maximum at ca. 454 nm. The emission has been assigned to ligand-to-metal charge transfer, LMCT, based upon the vibronic structure that is observed.
Inorganic Chemistry, 2003
The dinuclear gold(I) dithiophosphonate complex, [Au 2 (dtp) 2 ] (1), where dtp) [S 2 P(R)(OR′)]w... more The dinuclear gold(I) dithiophosphonate complex, [Au 2 (dtp) 2 ] (1), where dtp) [S 2 P(R)(OR′)]with R) p-C 6 H 4-OCH 3 ; R′) cC 5 H 9 , has been synthesized and its reaction studied with the phosphine ligands PPh 3 and Ph 2 P(CH 2) n-PPh 2 (n) 1−4). Compound 1 contains two gold atoms homobridged by the anionic dithiophosphonate ligand, forming an eight-membered ring complex in a chair form. After the reaction of 1 with diphosphine ligands, the dinuclear open-ring complexes Au 2 (dppm)(dtp) 2 (2), Au 2 (dppe)(dtp) 2 (3), Au 2 (dppp)(dtp) 2 (4), Au 2 (dppb)(dtp) 2 (5) were formed (dppm) diphenylphosphinomethane; dppe) diphenylphosphinoethane; dppp) diphenylphosphinopropane; dppb) diphenylphosphinobutane). The reaction with dppm is stoichiometry-dependent. Thus, when 1 reacts with 2 equiv of dppm, the ionic complex [Au 2 (dppm) 2 (dtp)]dtp forms. This dtp counterion was exchanged with tetrafluoroborate to yield [Au 2 (dppm) 2 (dtp)]BF 4 , the crystallization of which afforded two interconvertible isomers, 6-yellow and 7-white. Reaction of 1 with PPh 3 affords the tetracoordinate mononuclear complex [Au(dtp)(PPh 3) 2 ] (8). The molecular structures of 1−8 were confirmed by X-ray crystallography and show multiple coordination modes and geometries. The crystal structures of 1 and its reaction products with dppm (2, 6, 7) show short intramolecular Au‚‚‚Au aurophilic bonding interactions of 2.95−3.10 Å while no intermolecular interactions were discernible. However, reaction products of 1 with longer-chain Ph 2 P(CH 2) n PPh 2 ligands, n) 2−4, exhibit structures that lack both intra-and intermolecular Au‚‚‚Au interactions.
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Papers by Ahmed Emadeldeen Abdellatif Mohamed