A theoretical study of the staggered and eclipsed forms of the dinuclear complex Mn Re(CO)10

Abstract

Two possible conformers of the dinuclear complex Mn Re(CO) 10 , each of C 4v symmetry, with eclipsed and staggered conformations, have been analyzed theoretically. Using both the B3LYP and BP86 density functionals we find that the staggered form is lower in energy. A determination of the B3LYP potential energy surface as a function of the Mn-Re distance is presented for both conformers. The computed bond lengths, bond angles, and rotational constant for the staggered conformation compare favorably with the results from microwave experiments. The harmonic frequencies for the staggered structure have been determined using several basis sets, with both analytical and finite difference methods. These unscaled vibrational frequencies, together with their intensities for both infrared and Raman activity, are used to assign the three most intense experimental IR and Raman bands, and in particular, the CO region. The lowest A 2 vibration was calculated to occur at 41 cm Ϫ1 in the staggered conformer; this frequency becomes imaginary in the ͑saddle point͒ eclipsed form. Several fundamentals remain to be observed experimentally.

A Time-Dependent Density Functional Theory Study of the Structure and Electronic Spectroscopy of the Group 7 Mixed-Metal Carbonyls: MnTc(CO)10, MnRe(CO)10, and TcRe(CO)10

“…The first by Tanjaroon et al 15 reported the experimental rotational spectrum with a reported rotational constant of 200.55 MHz for the Re 185 isotopomer and 200.36 MHz for the Re 187 isotopomer using a highresolution pulsed beam microwave spectrometer with density functional (B3LYP and BP86) and ab initio calculations (SCF) used to determine the nuclear quadrupole coupling constants and electric field gradients. The second paper by Palmer and co-workers 16 reported in detail the possible equilibrium structures of MnRe(CO) 10 using density functional theory, using both the B3LYP and the BP86 density functionals. Two different conformers of C 4v symmetry were found in either staggered or eclipsed geometries with respect to rotation around the metal−metal bond.…”