First example of the formation of a Si–C bond from an intramolecular Si–H⋯H–C diyhydrogen interaction in a metallacarborane: A theoretical study

The recently reported crystal structure of [NMe4][1-SiMe2H-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)] shows short contacts between the Si–H proton acceptor group and the Cc–H proton donor moiety in the dicarbollide ligand. These short contacts were studied within the framework of the Quantum Theory of Atoms in Molecules (QTAIM) at different levels of DFT theory (B3LYP/6-311(d,p) and BP86/TZ2P(+)) that shows the existence of a bifurcated Si–H⋯H–Cc dihydrogen bond. This paper presents the study of an experimental uncommon Si–H group playing as proton acceptor bond in a dihydrogen bond where hydrides like M–H (M, as metal transition), B–H or Al–H usually perform this role. Furthermore, this paper accounts with a new simple method to estimate bonding energies for closed-shell intramolecular interactions in the scheme of Voronoi charge population analysis and Coulomb′s Law.

Graphical abstractThe Quantum Theory of Atoms in Molecules of Bader (QTAIM) at different levels of theory (B3LYP/6-311(d,p) and BP86/TZ2P(+)) has been used to study the H⋯H interactions found in the crystal structure of [1-SiMe2H-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)]−. This has permitted to define the H⋯H interactions and explain the formation of [1,1′-μ-SiMe2-3,3′-Co-(1,2-C2B9H10)2]−. The two Si–H⋯H–C contacts are interpreted as an asymmetric bifurcated DHB.Figure optionsDownload full-size imageDownload as PowerPoint slide