Solid state studies. Part IX. The vibrational spectra in the 2000 cm−1 region of mixed and isotopic crystals of manganese and rhenium pentacarbonyl chlorides and bromides

Ultrafast vibrational spectroscopy and relaxation in polyatomic molecules: Potential for molecular parallel computing

“…2 shows a schematic representation of the A 1 and E infrared active modes of Mn(CO) 5 Br. The monosubstituted carbonyl metal complex has a slightly distorted octahedral structure and possesses C 4v symmetry [16]. The more redshifted nondegenerate A 1 mode lies along the Br axis referred to as the axial carbonyl group and the doubly degenerate E mode is in the equatorial plane.…”

“…In the v = 1 manifold, the level with one quantum in the A 1 mode is coupled to two quasi degenerate levels with one quanta in the E mode with the rate r, and these three levels are coupled to a common bath level with rate b. In addition, there is a very fast solvent induced coupling between the two components of the E mode with a rate constant s. The Raman active B 1 carbonyl level with one quantum is further away in energy and is not taken into account in the relaxation scheme [16]. We therefore take into account four states in the one quantum v = 1 relaxation manifold (A 1 , E x , E y ; bath) where the semicolon separates the IR active and the bath modes.…”

“…The rate constant is expected to be very fast, on a subpicosecond to picosecond range, since the two components are, in zero order, degenerate. r is the rate constant for the coupling between these degenerate levels and the IR active A 1 level with one quanta of excitation, which lies 51 cm À1 below the E levels [16]. b is the slower rate constant for the coupling between the IR active levels and the bath state (0, 0, 0; 1).…”

Vibrational and Structural Dynamics of Mn(CO)5Br and Re(CO)5Br Examined Using Nonlinear Infrared Spectroscopy

“…With the aid of femtosecond IR laser pulses, the time resolution of this method is readily comparable to that of molecular dynamics simulations. Manganese and rhenium pentacarbonyl bromides (Mn(CO) 5 Br and Re(CO) 5 Br) are typical transition metal carbonyl coordination compounds that can be used as model molecules to understand the vibrational properties of these transition metal carbonyl species. The two complexes share the same formula, M(CO) 5 Br (M=Mn and Re respectively), and have C 4v symmetry.…”

“…In this work, we are particularly concerned with the carbonyl stretching mode (ν CO ) whose vibrational frequency is located in the 5-µm wavelength region (2000 cm −1 in wavenumber). The vibrational representation of M(CO) 5 Br complexes contains two infraredactive ν CO modes (A 1 and E) [5], which are mainly the axial and equatorial CO stretching vibrations respectively. While it has been established that the vibrational frequency of these two modes is in the order of E>A 1 , the vibrational and structural dynamics underneath these two modes, and the influence of central metal atom on the vibrational dynamics, are less under-stood.…”