Theoretical study of mixed hydrogen and dihydrogen bond interactions in BH4(NH3)n - Clusters

Ab initio calculations were used to analyze interactions of bh4- with 1-4 molecules of nh3 at the mp2/6-311++g(d,p) and the b3lyp/6-311++g(d,p) computational levels. in addition to h3b-hh- nh2 dihydrogen bond,the h2n-hnh3 hydrogen bonds were also predicted in clusters. negative cooperativity in clusters constructed from mixed h3b-hh-nh2 dihydrogen and h 2n-hnh3 hydrogen bonds are more remarkable. the negative cooperativity increases with size and number of hydrogen bonds in cluster. the b-h stretching frequencies show blue shifts with respect to cluster formation. greater blue shift in stretching frequencies was predicted for b-h bonds which did not contribute to dihydrogen bonding with nh3 molecules. the structures were analyzed with the atoms in molecules (aim) methodology. © 2013 abedien zabardasti et al.