Near-IR FT-Raman spectroscopy was used to probe the properties of three types of methyl imine/oxime B-13 model compounds in CHCl3 solution. These types differ in the nature of the 1,3-propanediyl chain and were selected to test the influence of electronic and steric effects on the Co-CH3 stretching (nu(Co-CH3)) frequency, a parameter related to Co-C bond strength. For the first type studied, [LCo((DO)(DOH)pn)CH3](0/+) ((DO)(DOH)-pn = N-2,N-2’-propane-1,3-diylbis(2,3-butanedione 2-imine 3-oxime)), nu(Co-CH3) decreased from 505 to 455 cm(-1) with stronger electron-donating character of the trails axial ligand, L, in the order Cl-, MeImd, Me(3)Bzm, 4-Me(2)-Npy, py, 3,5-Me(2)PhS(-), PMe(3), and CD3-. This series thus allows the first assessment of the effect of negative axial ligands on nu(Co-CH3); these ligands (L = Cl-, 3,5-Me(2)PhS(-), CD3-) span the range of trans influence. The CH3 bending (delta(CH3)) bands were observed at 1171, 1159, and 1150/1105 cm(-1), respectively.