CALCULATIONAL AND CONCEPTUAL STUDY OF CYANO DERIVATIVES OF DIBORANE AND THEIR ISO-ANALOGS

We present the prediction of the MBPT(2)/DZP structures, CCSD+T(CCSD)/ DZP and CCSD + T(CCSD)/cc-PVTZ energetics for 1,1-dicyanodiborane, tra ns-1,2-dicyanodiborane and mu,mu(C,C)-dicyanodiborane as well as for t he diisocyano counterparts. The molecules with three-centre-two-electr on (3c2e) bonds exhibit higher thermodynamic stability with respect to the H2BCN or H2BNC monomers than the mu,mu-isomers (cyano bridging) w hich are significantly less stable. Another possible reaction channel comprising the exchange reaction B2H6 + 2HCN --> C2H4B2N2 + 2H(2) exhi bits even more enhanced differences between 1,1-, 1,2- and mu,mu(C,C) isomers, respectively, and related isocyano molecules. The effects of electron correlation are analysed for complexation reactions, isomer o rdering and for various CN/NC isomerization reactions. Bonding analysi s in terms of SCF and MBPT(2) bond orders is presented. Possible candi dates for BNC-polymer modeling are also suggested on the basis of thes e molecular calculations.