Zi-Jian Yao

Iridium-Mediated Regioselective B–H/C–H Activation of Carborane Cage: A Facile Synthetic Route to Metallacycles with a Carborane Backbone

One-pot reactions of carborane carboxylic acids (L), [Cp*IrCl2]2, and silver salt are reported, which lead to regioselective B-H or C-H bond activation at ambient temperature in good yields. This process is demonstrated for three carborane (o-, m-, p-) dicarboxylates, and metal-mediated B-H functionalization of a p-carborane derivative is accomplished for the first time. Two metal-induced self-assembly routes to tetra-nuclear metallacycles 3 and 5 were performed through B(4, 7)/H and B(2, 10)/H activation, respectively, and the two metallacycles were found to be stable and to exist in solution as discrete complexes. Different activation modes in the carborane cage were ascribed to the characteristic structure of the products and the electronic density differences. The analogous reaction of o-carborane monocarboxylate with the same metal precursor gave the C-H activation complex 6, indicating that the B-H bond is more stable than the C-H bond in this carborane cage. The selective activation was confirmed by DFT calculation results. In this study, a facile and efficient synthetic route has been developed through specific B-H bond activation to construct carborane-based metallacycles that are unavailable by conventional methods.

Zwitterionic half-sandwich Rh and Ir complexes containing a diphosphine nido-carborane ligand: synthesis, structure transformation and application in H2 activation

Several novel zwitterionic half-sandwich complexes and pseudocloso metallacarboranes based on 1,2-(PPh(2))(2)-1,2-C(2)B(10)H(10) were successfully prepared, and further study proved that some of them can activate H(2) to form the metal hydride complexes Cp*M(H)(7,8-(PPh(2))(2)-7,8-C(2)B(9)H(10)) (M = Rh, Ir).

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 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.