308339-57-3Relevant academic research and scientific papers
Synthesis, structure, and reactions of a binuclear gold(I)-gold(III) complex containing bridging and bidentate (2-diphenylphosphino-6-methyl)phenyl groups
Bhargava, Suresh K.
, p. 5628 - 5635 (2000)
Reaction of the organolithium reagents (C6H3-2-PPh2-6-Me)Li or (C6H3-2-PPh2-5-Me)Li with [AuBr(PEt3)] gives the corresponding cyclometalated digold(I) complexes [Au2(μ-C6H3-2-PPh2-n-Me)2] (n = 6, 1a; n = 5, 1b), the metal-metal distance in 1a, 2.861(2) angstrom, being similar to that in the unsubstituted compound [Au2(μ-2-C6H4PPh2)2]. Both complexes oxidatively add halogens to give metal-metal bonded digold(II) complexes [Au2X2(μ-C6H3-2-PPh2-n-Me)2] [n = 6, X = Cl (2a), Br (3a), I (4a); n = 5, X = Cl (2b), Br (3b), I (4b)], and 1b also adds dibenzoyl peroxide to give the bis(benzoato)digold(II) complex [Au2(O2CPh)2 (μ-C6H3-2-PPh2-5-Me)2] (5b), whereas 1a is unreactive. The behavior of the 6- and 5-methyl-substituted digold(II) complexes in solution is very different. Complexes 2a-4a isomerize in solution above -20°C to give gold(I)-gold(III) complexes [XAuI(μ-2-Ph2PC6H3-6-Me)-AuIII X{η2-(C6H3-2-PPh2-6-Me)}] [X = Cl (6a), Br (7a), I (8a)], whereas complexes 2b-4b isomerize more slowly in solution by C-C coupling to give digold(I) complexes [Au2X2{μ-2,2′-Ph2P(5,5′- Me2C6H3C6H3)PPh2}] [X = Cl (6b), Br (7b), I (8b)] containing (5,5′-dimethyl-2,2′-biphenylyl)bis(diphenylphosphine) (12b); the structures of 8a and 8b have been determined by X-ray crystallography. Complex 8a contains linearly coordinated gold(I) and planar coordinated gold(III) atoms separated by 3.4692(7) angstrom; one arylphosphine group bridges the metal atoms, the other acts as a bidentate chelate ligand to gold(III). Complexes 6a-8a can be oxidized further by halogens to give either gold(I) complexes of (2-halo-3-methylphenyl)diphenylphosphine, [AuX{Ph2P(C6H3-2-X-3-Me)] [X = Br (10a), I (11a)], arising from electrophilic cleavage of the Au-C bonds, or a binuclear digold(III) complex [Cl3Au(μ-C6H3-2-PPh2-6-Me)AuCl{η2- (C6H3-2-PPh2-6-Me)}] (9a) in which the gold(III)-carbon bonds are retained. The differences in oxidative addition behavior between the 6- and 5-methyl-substituted series of compounds are believed to be caused mainly by the steric effect of the 6-methyl group adjacent to the gold-gold axis.
