CARBON HYDROGEN ACTIVATION OF KETONES BY 2-PHENYLAZO-PHENYLGOLD(III) COMPLEXES TO GIVE KETONYLGOLD(III) COMPLEXES

Complexes [AuR(acac-C)Cl] {R = pap (C6H4N=NPh-2) 1a or mpap [C6H3(N=NC6H4Me-4)-2-Me-5] 1b; Hacac = acetylacetone} or 'AuR(Cl)(OCIO3)' (R = pap 2a or mpap 2b) react with various ketones MeC(O)R' to give [AuR{CH2C(O)R'}Cl] [R = pap, R'= Et 3, Pr(n) 4, Pr(i) 5, Bu(i) 6 or C6H2(OMe)3-3,4,5 7; R = mpap, R' = Me8]. Whereas 1a does not react with MeC(O)CH2Cl, 2a gives a mixture of the expected [Au(pap){CH2C(O)CH2Cl}Cl] and [Au(pap)Cl2]. However, other ketones [R'C(O)R"] (R' = Me; R" = Ph, CH2=CH, trans-PhCH=CH or MeCO; R' = R" = CH2Cl or Et) or 2-methylcyclohexanone do not react at room temperature with 2a. The reactions of 2a with other species containing activated methyl groups [MeCO2Et, MeC(O)NH2 or MeCN] either do not occur or give products in which there is no carbon-hydrogen activation. Thus, 2a reacts with dimethyl sulfoxide (dmso) to give the first organogold(III) complex with this ligand, [Au(pap)(dMSo)2][ClO4]2 9. It reacts with Nal to give [Au(pap)Cl(I)] 10. Complex 8 reacts with NaClO4.H2O and pyridine (py) or 2,2'-bipyridine (bipy) to give [Au(mpap){CH2C(O)Me}L]ClO, (L = py 11 or bipy 12). The following reactions were also studied: [Au(pap)Cl(acac-C)] + PPh3 or AgClO4 to give [Au(pap)Cl(acac-C)(PPh3)] 13 or [Au(pap)(acac-O,O')] ClO4 14, respectively. Complexes 13 and 14 do not give an acetonyl complex with acetone; 14 is the first cationic acetylacetonatogold(III) complex. A plausible reaction pathway is proposed for ketone carbon-hydrogen activation starting from complexes 2. Low-temperature crystal structures were determined for [Au(mpap)Cl2] (space group P1, a = 7.902(2), b = 9.527(2), c = 10.378(3) angstrom, alpha = 86.77(2), beta = 77.32(2), gamma = 67.42(2)-degrees, R = 0.024] and 11 [space group P2(1)/n, a = 8.693(5), b = 15.800(8), c = 16.489(8) angstrom, beta = 94.51 (4)-degrees, R = 0.027]. The latter is the first crystal structure of an acetonylgold(III) complex, and it could be shown conclusively that the CH2C(O)Me group is bonded through the carbon atom. Both structures show the expected square-planar co-ordination around the gold atom, with some distortion from the narrow chelate rings. In the first complex the higher trans influence of the aryl group leads to a lengthening of the trans Au-Cl bond (2.347 angstrom) with respect to the cis bond (2.274 angstrom).