SYNTHESIS OF [AU3]3+, [AU2AG]3+, AND [AU2CU]3+ LOOSE CLUSTERS

(2-Pyridylmethyl)triarylphosphonium salts, [R3PCH2(py-2)]X (py = pyridyl-2) react (i) with AgX, in 1:1 or 2:1 molar ratios, to give N-coordinated complexes [AgX2(py-CH2PTo3-2)] [X = ClO4, To = C6H4Me-4 (1)] or [AgX3{py-CH2PTo3-2}2] [X = ClO4 (2a), CF3SO3 = TfO (2b)], respectively, or (ii) with [AuCln(tht)] (n = 1 or 3, tht = tetrahydrothiophene) to afford [R3PCH2(py-2)][AuCln+1] (n = 1, R = Ph (5a), To (5b); n = 3, R = Ph (6a), To (6b)] or (iii) with Tl(acac) (1:1, acacH = acetylacetone, X = AuCl2) or ppn[Au(acac)2] [2:1, ppn = bis(triphenylphosphoranylidene)ammonium] or [Au(acac)(PR'3)] (1:2) to yield the ylide complexes [AuCl{CH-(PR3)(py-2)}] [R = Ph (7a), To (7b)], [Au{CH(PTo3)(py-2)}2]ClO4 (8), [(AuPR'3)2{mu-{C(PR3)(py-2)}}]ClO4 [R = R' = Ph (9a), R = To, R' = C6H4OMe-4 = pmp (9b)], respectively. Complex 1 reacts with PR'3 (1:1) to give [Ag(ClO4)2(PR'3){py-CH2PTo3-2}] [R' = Ph (3a), pmp (3b)]. 3a reacts with [AuCl(tht)] (1:1) leading to [Au(PPh3)(py-CH2PTo3-2)](ClO4)2 (4). Complex 9a reacts with AgNO3 (1:1) to give [(AuPPh3)2{mu-{C(PPh3)(py-2)}}{mu-Ag(eta2-O2NO)(OClO3)}] (10), which reacts with [AuCl(PPh3)] and NaClO4.H2O (1:1:1) leading to [(AuPPh3)2{mu-{C(PPh3)(py-2)}}(AuPPh3)](ClO4)2.2H2O (11). Complexes 9a and 9b react with CuCl to give [(AuPR'3)2{mu-{C(PR3)(py-2)}}(CuCl)](ClO4) [R = R' = Ph (12a); R = To, R' = pmp (12b)], respectively. The X-ray crystal structures of 9b and 10.CH2Cl2.H2O at 178 K show that weak interactions between both Au centers occur [2,949(1) and 3.078(1) angstrom, respectively]. The configuration of the N lone pair with respect to the Au2 moiety is anti in 9b while syn in 10 because two Au ... Ag weak interactions [2.926(1), 3.006(1) angstrom] seem to act as a conformation-determining force.