SYNTHESIS AND STRUCTURE OF [(PH3PAU)6CO(C O)2](PF6) AND [(PH3PAU)7CO(CO)2](PF6)2

By the reaction of [(Ph3PAu)4Co(CO)3]+ with OH-in the presence of exce ss Ph3PAuCl the larger cluster cations [(Ph3PAu)6Co(CO)2]+ (1) and [(P h3PAU)7Co(CO)2]2+ (2) can be built up with 1 being the main product. 1 crystallizes with PF6- as counterion in the monoclinic space group C2 /c with a = 3 008.3(6); b = 1 339.1(2); c = 2 909.4(6) pm; beta = 103. 08(1)-degrees; Z = 4. The inner core of the cluster cation 1 with the symmetry C, has the form of a bicapped trigonal bipyramid with the het eroatom in equatorial position, and distances Au-Au between 280.4(1) a nd 288.4(1) pm and, Co-Au between 254.9(1) and 257.1(2) pm. 2 . (PF6)2 crystallizes in the triclinic space group P1BAR with a = 2155.7(1); b = 1 720.6(1); c = 3 543.6(1) pm; alpha = 91.89(1)-degrees; beta = 97. 51(1); gamma = 89.92(1)-degrees; Z = 4. The unit cell contains two sym metry independent cluster cations 2 of about the same geometry. The cl uster skeleton Au7Co can be described as fragment of an icosahedron fo rmed by seven gold atoms with the Co atom in its center. The Au-Au dis tances range from 274.8(3) to 332.6(3) pm, and the Co-Au distances are 256.8(6) to 264.7(5) pm. The bonding in 1 and 2 is discussed.