Dihydrogen Bonds in Solid BH_3NH_3

摘要

The "dihydrogen bond" D-H~(delta+...delta-)H-E-where D is a typical electrostatic atom such as nitrogen or oxygen,and E is a transition metal or boron-was first described by Crabtree and co-workers.Both inter- and intramolecular versions of this bond have been cited,and with typical energies in the range of 12-28 kJ mol~(-1),they are comparable in strength to conventional hydrogen bonds.In particular,the N-H~(delta+...delta-)H-B intermolecular contact in solid-state BH_3NH_3 has received special attention.The absence of nonbonding valence electrons on boron negates a possible H~(delta+...delta-)E interaction that could arise if E were a d-block element.Thus,for BH_3NH_3 the H...H contact must result from a sigma-type interaction.