Reactivity of half-sandwich metal complexes with sterically encumbered N,N′-bis(2,6-diisopropylphenyl) group-substituted carboranylamidinate ligands

Reactions of [Cp*MCl2](2) (Cp* is eta(5)-C5Me5, M = Ir, Rh) with carboranylamidinate ligand CabNH (1a) (Cab(N)H is 1-R-1-1,2-C2B10H11, R-1 = (DippNH)C(=NDipp), Dipp is diisopropylphenyl) in the presence of the BuLi excess produced 16-electron half-sandwich iridium and rhodium complexes Cp*M(Cab(N)-Dipp) (2a,b) (Cab(N)-Dipp is (DippN)C(=NDipp)(closo-1,2-C2B10H10), M = Ir (a), Rh (b)). Unexpected neutral closo-metallacarboranes closo-[1-R-2-3-(eta(5)-Cp*)-3,1,2-MC2B9H10] (3a, b) (R-2 = (NHDipp)C(=NDipp), M = Ir (a), Rh (b)) were prepared by the reaction of the deboronated zwitterionic ligand Dcab(N)H (1b) (Dcab(N)H is nido-7-[C(NHR3)(2)](+)[7,8-C2B9H11](-), R-3 = Dipp) with [Cp*MCl2](2). All compounds were fully characterized by elemental analysis, IR spectroscopy, mass spectrometry, and NMR spectroscopy. Structures of compounds 1a, b and 3a, b were confirmed by single crystal X-ray diffraction.