Prediction of the geometries of simple transition metal polyhydride complexes by symmetry analysis

The principle of correspondence between the; symmetry decompositions of the valence atomic orbitals (AOs) of the central metal and those of the hydrid e ligands is used to predict and rationalize the geometries of simple trans ition metal polyhydride complexes, In this orbitally ranked symmetry analys is method (ORSAM) the minimum energy structures have metal AOs whose irredu cible representations match those of the hydrides. Tn agreement with previo us work, the hydrides prefer to bond to the metal (n + 1)s and nd orbitals, but ORSAM also includes (n + 1)p orbitals in a natural pray and avoids hav ing to postulate hypervalency for transition metal complexes with electron counts greater than 12. Comparison with ab initio structures of 114 simple transition metal polyhydrides shows that: ORSAM correctly predicts and rati onalizes the geometries of both classical and nonclassical complexes.