Chemistry of Polynuclear Metal Complexes with Bridging Carbene or Carbyne Ligands. Part 87. Docosahedral Carbaborane (alkylidyne)Tungsten Complexes.

摘要

In a series of recent papers we have demonstrated that salts of the anionic complexes W(Triple bond CR)(CO)2(N5-C2B9H9Me2) (R = alkyl or aryl) and Mo(Triple Bond CC6H4Me-4)(CO)-P(OME)3 -(N5-C2B9H9Me2)-anionic complexes can be used as precursors for the synthesis of a variety of compounds with heteronuclear metal-metal bonds. In reactions of these anionic species the C Triple Bond M (M double bond W or Mo) groups ligate low valent metal-ligand fragments, thereby forming products having core structures based on a dimetallacyclopropene ring. However, an intriguing aspect of this synthetic procedure is the regularity with which the nidoicosahedral Eta 5-C2B9H9Me2 fragment, bonded to the tungsten or molybdenum centres, adopts a non-spectator role. Initially this takes the form of cage slippage so as to form an exopolyhedral B-H-metal bond. However, further transformations often follow, promoted either by migration of the agostic hydrogen to the alkylidyne group of by loss of molecular hydrogen. As a result, several novel compounds have been characterised with molecular structures of a hitherto unknown type. In this paper we introduce a new but related series of reactions based on using the anionic salt complexes as reagents for preparing polynuclear metal compounds. These salts contain the thirteen-vertex docosahedral C2B10W framework, rather than the twelve-vertex icosahedral C2B9W group involved in earlier work. A preliminary account has been given of the results described in this paper. Keywords: Reprints; tungsten; Iron; Carbaborne; Alkylidyne. (KT)