Theoretical and Experimental Investigations on Hypoelectronic Heterodimetallaboranes of Group 6 Transition Metals

Density functional theory (DFT) has been used to probe
the bonding
and electronic properties of dimolybdaborane [(Cp*Mo)2B5H9], 1 (Cp* = η5-C5Me5), and several other heterodimolybdaborane clusters,
such as [(Cp*Mo)2B5(μ3-OEt)­H7] (2), [(Cp*Mo)2B5(μ3-OEt)­(n-BuO)­H6] (3), [(η5-C5H5W)2B4H4S2] (4), and [(Cp*Mo)2B4H4E2] (5–7, where, for 5, E = S, for 6, E
= Se, and for 7, E = Te). The DFT results were also used
to address some key points such as (i) the metal–metal bond
length, (ii) the location and number of bridging and terminal hydrogen
atoms, (iii) the molecular orbital analysis, and (iv) the assignment
of 11B and 1H NMR chemical shifts. These studies
further provide meticulous insight into similarities and differences
between various dimetallaborane clusters 1–7. In addition, the crystal structures of 5 and 7 are reported, which come on top of the already existing
literature of dimetallaboranes and support the theoretical findings.