SYNTHESES AND STRUCTURAL CHARACTERIZATIONS OF HYPHO-METALLADITHIABORANE AND ARACHNO-METALLADITHIABORANE CLUSTERS

The hypho-S2B6H9- anion has been employed to generate a series of new arachno- and hypho-metalladithiaborane clusters. Depending upon the conditions, the reaction of hypho-S2B6H9- with [(eta-6-C6Me6)RuCl2]2 yields either hypho-1,2,5-(eta-6-C6Me6)RUClS2B6H9 (I) or arachno-7,6,8-(eta-6-C6Me6)RuS2B6H8 (II). II may also be produced directly from I by reaction of I with proton sponge. Single-crystal X-ray studies of I and II have confirmed that these nine-vertex clusters adopt structures consistent with their respective 26- and 24-skeletal-electron counts in which the ruthenium atom is bound to the dithiaborane cage in either an eta-2- or eta-4-fashion. The ruthenadithiaborane cage framework observed for I can be derived from an icosahedron by removal of three vertices, while that of II is based on an octadecahedron missing two vertices. Reactions of hypho-S2B6H9- with *CPCO(CO)I2 or CpCo(CO)I2 gave the complexes hypho-1,2,5-*CpCo(I)S2B6H9 (III), arachno-7,6,8-*CpCoS2B6H8 (IV), and arachno-7,6,8-CpCoS2B6H8 (V). Reaction of the anion with (dppe)NiCl2 gave the complex arachno-7,6,8-(dppe)NiS2B6H8 (VI), the structure of which was shown to be similar to that of II by means of a single-crystal X-ray determination. The complex arachno-7,6,8-(PMe3)2Rh(H)S2B6H8 (VII) was obtained by the reaction of the anion with (PMe3)2Rh(CO)Cl and is proposed to form by a process involving an oxidative addition of a cage-bridging hydrogen to the rhodium followed by insertion of the resulting (PMe3)2Rh(H) fragment into the dithiaborane cage framework.