| Compounds in which carbollide groups are pentahapto coordinated to a transition-metal ion were first reported many years ago. However, until recently the chemistry of this class of metallacarborane had been underdeveloped, especially for the monocarbollide species. In this work, the synthesis, structure and reactivity of compounds in which metal atoms (M = Mo, W, Re, Fe, and Ru) are ligated by the open pentagonal faces of [ nido-7,8-C2B9H11]2- , [nido-7-CB10H11]3- , and [7-NHBut-nido-7-CB10H 10]3- groups are described. Frequently, the cage adopts a non-spectator role in reactions with various metal fragments and other electrophiles in the presence of donor ligands, resulting in the formation of molecules with unusual structures and reactivities. In this regard, selected reactions of the complexes [3-CO-3-PPh3-3-THF-closo-3,1,2-RuC 2B9H11], [3,3,3-(CO)3-closo -3,1,2-ReC2B9H11]- , [2,2,2-(CO)3-2-L-closo-2,1-MoCB 10H11]- (L = CO, PPh3), [2,2-(CO) 2-2-L-closo-2,1-FeCB10H11] (L = CO, PPh3), [2,2,2-(CO)3-2-PPh3- closo-2,1-WCB10H11]- and [1,2-mu-NHBut-2,2,2-(CO)3-closo-2,1-MoCB 10H10]- are discussed in conjunction with the single crystal X-ray structures of various unique products. |
