Synthesis of the First <i>hyper-closo</i>-Type Monocarbon Ruthenacarboranes by Polyhedral Contraction of [<i>nido</i>-B₁₀H₁₂CH]^- and Molecular Structure of 2-Cl-2,5-(Ph₃P)₂-2-H-3,9-(MeO)₂-2,1-RuCB₈H₆

Abstract

Treatment of [nido-B10H12CH]-Cs+ with RuCl2(PPh3)3 in methanol under gentle reflux afforded the two novel 10-vertex monocarbon ruthenacarboranes 2-Cl-2,5-(Ph3P)2-2-H-3,9-(MeO)2-2,1-RuCB8H6 (3) and 2,2-(Ph3P)2-2-H-3,9-(MeO)2-2,1-RuCB8H7 (4) along with a small amount of the 8-vertex complex (PPh3)2HRuCB6H4(OMe)3 (6). The 10-vertex clusters 3 and 4 on the basis of their capped-tricapped-trigonal-prismatic geometry, established for 3 by a single-crystal X-ray diffraction study, and the formal Wadian electron-counting arguments can be regarded as hyper-closo species having n rather than n + 1 skeletal electron pairs.