Small Heteroborane Cluster Systems. 8. Preparation of Phosphaborane Clusters from the Reaction of Polyhedral Boranes with Low-Coordinate Phosphorus Compounds:  Reaction Chemistry of Phosphaalkynes with Decaborane(14)¹

Abstract

The room-temperature reaction of equimolar quantities of phosphaalkyne RCtP (2a; R ) t Bu; 2b, R ) adamantyl) with the decaborane(12)-Lewis base adduct B 10 H 12 ‚2CH 3 CN (3) resulted in the formation of new phosphaborane compounds (phosphine-methylene ylides), nido-RC(H)PB 10 H 13 (4a, R ) t Bu; 4b, R ) adamantyl), in good yield (approximately 50% each). These slightly air-sensitive compounds were fully characterized by 1 H, 11 B, 13 C, and 31 P NMR, 2D 11 B-11 B COSY NMR, FT-IR, and mass spectroscopic analyses. The structures of 4a and 4b are proposed to consist of a nido-PB 10 framework formally based upon a 26skeletal-electron nido-[B 11 H 11 ] -parent compound. Only the phosphorus atom was observed to be incorporated into the polyhedral framework with an exopolyhedral C(H)R group doubly bound to the cage phosphorus atom. Two related mechanisms are proposed to account for the observed products from these reactions.