The Infrared Spectra and Normal Coordinate Treatments of X3M-Mn(CO)5 (X=H and CH3, M = Ge and Si)†

Abstract

The infrared spectra of (CH3)3Ge-Mn(CO)5 have been measured in the region of 2200~60 cm-1, and normal coordinate analyses have been made for three molecules, (CH3)3Ge-Mn(CO)5, H3Ge-Mn(CO)5, and H3Si-Mn(CO)5, on the basis of a modified Urey-Bradley force-field. The π-interaction between the IV b metal and manganese atoms for the present series of compounds was found to be weaker than that of halogen analogues on the basis of the set of the force constants, K(M-Mn), K(Mn-C), and K(C-O). The three force constants of a series of analogous compounds, subjected to the normal coordinate analyses were compared with that of Cl3Sn-Mn(CO)5. The plot of the difference of K(M-Mn) for each compounds from that of Cl3Sn-Mn(CO)5 against the difference of K(Mn-C) revealed that (1) the degree of the π-interaction between the IV b metal and manganese atoms and (2) the extent or strength of the metal-metal interaction, (σ + π), were controlled by ligands on IV b metal atom, regardless of its componet metal atoms. © 1974, The Chemical Society of Japan. All rights reserved.