Bond angles in transition metal tetracarbonyl compounds: A further test of the theory of hybrid bond orbitals.

An equation for the bond angles OC-M-CO for tetracarbonyl groups in which the transition metal atom M is enneacovalent, derived from the simple theory of hybrid sp(3)d(5) bond orbitals, is tested by comparison of the calculated values of the angles with the experimental values reported for many compounds containing M(CO)(4) groups, especially those with M = Fe, Mn, Re, Cr, or Mo. The importance of the energy of resonance of single bonds and double bonds in stabilizing octahedral complexes of chromium and manganese with carbonyl, phosphine, arsine, and thio groups is also discussed.