Manganа- and rhena-copper carboranes based on the medium-size non-icosahedral 5,6-dicarba-nido-decaborane

Reaction of the deprotonated medium-size non-icosahedral carborane 5,6-nido-C2B8H12 (1) with Re(CO)5Cl affords tricarbonyl anionic complexes of Re [1,1,1-(CO)3-isonido-1,2,4-ReC2B8H10]- as PPh4- 3a and tmndH- 3b salts (tmnd — N,N,N′,N′-tetramethyl-1,8-diaminonaphtaline). Treatment of [tmndH][1,1,1-(CO)3-isonido-1,2,4-MC2B8H10]- (M = Mn 2b, Re 3b) with the equivalent amount of CuCl and PPh3 in CH2Cl2 leads to formation of two isomers of bimetallic complexes [1,3,7(6)-{Cu(PPh3)}-3,7(6)-μ-H2-1,1,1-(CO)3-isonido-1,2,4-MC2B8H8] (M = Mn 4, Re 5) with two B-H⋯Cu bonds. All newly obtained compounds were characterized by a combination of analytical and multinuclear NMR spectroscopic data and IR spectroscopy. The structures of complexes 3b and 4 were researched by X-ray diffraction studies. The nature of interaction between {Cu(PPh3)} and mangana-carborane fragments was clarified based on the computed electron density critical points (within QTAIM framework) and Density Overlap Regions Indicator (DORI) distributions. Transition state between the two diastereomers of 4 was located, the isomerization rate was found to be of order of 1 s−1. © 2020 Elsevier B.V.