Reactions of [Cp*MCl2]2 (Cp* is η5-C5Me5, M = Ir, Rh) with carboranylamidinate ligand CabNH (1a) (CabNH is 1-R1-1,2-C2B10H11, R1 = (DippNH)C(=NDipp), Dipp is diisopropylphenyl) in the presence of the BuLi excess produced 16-electron half-sandwich iridium and rhodium complexes Cp*M(CabN-Dipp) (2a,b) (CabN-Dipp is (DippN)C(=NDipp)(closo-1,2-C2B10H10), M = Ir (a), Rh (b)). Unexpected neutral closo-metallacarboranes closo-[1-R2-3-(η5-Cp*)-3,1,2-MC2B9H10] (3a,b) (R2 = (NHDipp)C(=NDipp), M = Ir (a), Rh (b)) were prepared by the reaction of the deboronated zwitterionic ligand DcabNH (1b) (DcabNH is nido-7-[C(NHR3)2]+[7,8-C2B9H11]−, R3 = 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.