Mulliken n.aσ and bπ.aσ complexes B…Cl2 in the gas phase: rules for predicting angular geometries and nature of the interaction

Comparison of the angular geometries of a series of B 3. Cl2 complexes of the Mulliken n.aσ and bπ.aσ type with those of the series B3.Cl2, where B = CO,, HF, PH3, H2S, C2H2, C2H4, HCN, and NH3, reveals the two series to be isostructural for a given B. Rules for predicting the angular geometries of the B3.HCl apply to the B3.Cl2 also. Discussions of the extent of electric charge redistribution within Cl2 on formation of B3.Cl2 and the strength of the interaction show why the rules apply. A shortened van der Waals distance r(B3.Cl) when modelling B3.Cl2 is proposed.