Rhodium(I) complexes of α-keto-stabilised 1,2-bis(diphenylphosphino)alkane mono ylides
Rhodium(I) complexes of the hybrid ylide-phosphine ligands, Ph2P(CH2)nPPh2(CHC(O)C6H5) (n = 1: dppm-yl, or 2: dppe-yl) have been synthesised from [Rh(μ-C1)(COD)]2 (COD = 1,5-cyclooctadiene) and characterized by NMR spectroscopic and X-ray structural methods. The dppe-yl behaves as an ambidentate ligand; it functions as a monodentate P-donor ligand with a dangling ylidic carbon in the neutral chloro complex, [(COD)Rh(Cl)(dppe-yl)] (1), whereas replacement of the chloride by a non-coordinating counter anion results in the formation of the complexes, [(COD)Rh(L-L’)]+ (L-L’ = dppe-yl (2) or dppm-yl (3)) respectively in which the ligands are bonded to the metal via the phosphorus and the ylidic carbon atoms. The 1,5-cyclooctadiene (COD), present in the Rh(I) precursor, remains intact in the products. The structures of1,2 and3 have been confirmed by X-ray crystallography.
Mercury(II) complexes of unsymmetric phosphorus ylides: Synthesis, spectroscopic and antibacterial activity studies
Abstract The reaction of Ph 2 PCH 2 PPh 2 (dppm) with 2-bromo-3-nitroacetophenone and 2,2′,4′-trichloroacetophenone in chloroform produce the new phosphonium salts [Ph 2 PCH 2 PPh 2 CH 2 C(O)C 6 H 4 NO 2 ]Br ( 1 ) and [Ph 2 PCH 2 PPh 2 CH 2 C(O)C 6 H 3 Cl 2 ]Cl ( 2 ). Further, by reaction of the monophosphonium salts of dppm with the strong base triethylaminethe corresponding bidentate phosphorus ylides, Ph 2 PCH 2 PPh 2 C(H)C(O)C 6 H 4 NO 2 ( 3 ) and Ph 2 PCH 2 PPh 2 C(H)C(O)C 6 H 3 Cl 2 ( 4 ) were obtained. The reaction of these ligands with mercury(II) halides in dry methanol led to the formation of the mononuclear complexes {HgX 2 [(Ph 2 PCH 2 PPh 2 C(H)C(O)C 6 H 4 NO 2 )]} [X = Cl ( 5 ), Br ( 6 ), I ( 7 )] and {HgX 2 [(Ph 2 PCH 2 PPh 2 C(H)C(O)C 6 H 3 Cl 2 )]} [X = Cl ( 8 ), Br ( 9 ), I ( 10 )]. Characterization of the obtained compounds was performed by elemental analysis, IR, 1 H, 31 P and 13 C NMR. The structure of compound 1 being unequivocally determined by single crystal X-ray diffraction techniques. The mass spectrum of compound 6 (as an instance) also demonstrates the synthesize of these compounds. In all complexes the title ylides are coordinated through the ylidic carbon and the phosphine atom. These compounds form five membered ring under complexation. The antibacterial effects of DMSO solutions of the ligands and their metal complexes were evaluated by the disc diffusion method against six Gram positive and negative bacteria. All compounds represent antibacterial activity against these bacteria with high levels of inhibitory potency exhibited against the Gram positive species.
Synthesis and structural characterization of polynuclear complexes containing the eight-electron donor bis(diphenylphosphino)methanediide ligand
The compound [AuR2{(Ph2P)2CH}](R = C6H5) reacts with various gold(I) or silver(I) compounds possessing a labile ligand such as tetrahydrothiophene or perchlorate to give [AuR2{(Ph2P)2CH(ML)}]ClO4(ML = AuPPh3, AuCH2PPh3 or AgPPh3). Treatment of these derivatives with [Au(acac)(PPh3)] or [N(PPh3)2][Au(acac)Cl](acac = acetylacetonate) leads to [AuR2{(Ph2P)2C(AuPPh3)(ML)}]ClO4 or [AuR2{(Ph2P)2C(AuPPh3)(AuCl)}], in which the doubly deprotonated bis(diphenylphosphino)methanediide ligand is an eight-electron donor. The compound [AuR2{(Ph2P)2C(AuPPh3)2}]ClO4 can also be obtained by reaction of [AuR2{(Ph2P)2CH2}]ClO4 and [Au(acac)(PPh3)] in 1 : 2 molar ratio. The reaction of [AuR2{(Ph2P)2CH(AuR)}] with [Au(acac)(PPh3)] or [N(PPh3)2][Au(acac)Cl] gives the trinuclear complexes [AuR2{(Ph2P)2C(AuR)(AuPPh3)}] or [N(PPh3)2][AuR2{(Ph2P)2C(AuR)(AuCl)}], whereas it reacts with [N(PPh3)2][Au(acac)2](molar ratio 2 : 1) affording the pentanuclear complex [N(PPh3)2][{AuR2[(Ph2P)2C(AuR)]}2Au]. Another pentanuclear derivative [{AuR2[(Ph2P)2C(AuPPh3)]}2Au]ClO4 is obtained by treatment of [{AuR2[(Ph2P)2CH]}2Au]ClO4 with 2 equivalents of [Au(acac)(PPh3)]. The compounds were characterized by elemental analysis, IR and NMR spectroscopy, and some by fast atom bombardment mass spectrometry. The crystal structure of [AuR2{(Ph2P)2C(AuPPh3)2}]ClO4·CH2Cl2 was confirmed by X-ray diffraction analysis. The complex contains a triangular Au2C unit with a short Au ⋯ Au contact of 2.826(2)A and a narrow Au(1)–C(1)–Au(2) angle of 85.4(7)°.