Dihydrogen bond cooperativity in (HCCBeH)n clusters.

A theoretical study has been carried out on the clusters formed by the association of ethynylhydroberyllium (HC[triple bond]CBeH) monomers. The monomer presents a linear disposition with a dipole moment of 0.94 D. Clusters from two to six monomers have been calculated for three different configurations (linear, cyclic with dihydrogen bonds, and cyclic with hydrogen bonds to the pi-cloud), the third one being the most stable. The electronic properties of the clusters have been analyzed by means of the atoms in molecules and natural bond orbitals methodologies. Cooperative effects, similar to the ones described for standard hydrogen bonded clusters, are observed in those configurations where dihydrogen bonds are the main interacting force.