The synthesis and crystal structure of a new copper(I) polymer, [{(Ph3P)2Cu2(μ-Cl)2(μ-pyrazine)}∞], are reported. The polymer is photoluminescent with its emission maximum at 16 340 cm-1 at a temperature of 20 K. The emitting state is assigned with the assistance of excited state distortions determined by using resonance Raman intensities. The polymer consists of (PPh3)(pyz)Cu(μ-Cl2)Cu(pyz)(PPh3) units in which pyrazine ligands bridge copper pairs to form a chain of dimers. The packing arrangement contains two inversion centers. Each dimer has an inversion center between the two coppers and the bridging chlorine atoms. A second inversion center is located in the center of the pyrazine ligand, which links the dimers in an infinite linear chain. The nitrogen atom of the pyrazine, the phosphorus atom of one triphenylphosphine, and the two chlorine atoms form a slightly distorted tetrahedron about the copper. The largest distortions in the lowest excited electronic state, determined from the resonance Raman intensities, occur along totally symmetric modes of the pyrazine ligand. The emission is assigned to copper(I) to pyrazine charge transfer.

The electronic absorption and resonance Raman spectra of the metal diimine dithiolate complexes M(mnt)-(baba) where M = Ni and Pd, mnt = l,Zmaleonitrile, and baba = biacetylbisaniline are reported. The absorption spectra obtained from a low temperature frozen glass exhibit weakly resolved vibronic structure.The spectra are interpreted by using the time-dependent theory of spectroscopy. The electronic spectra are fit by using a calculation method for electron transfer spectra that includes coupling between potential surfaces (including the coupling of electronic and nuclear motions, i.e. the breakdown of the Born-Oppenheimer approximation). The results of this detailed calculation are compared to those involving uncoupled potential surfaces. Quantitative bond length changes are calculated. The distortions on both ligands that are observed support the assignment of the lowest energy excited state as arising from a ligand to ligand electron transfer transition from the dithiolate ligand to the diimine ligand.

The resonance Raman spectra of the metal-to-metal charge transfer (MMCT) mixed-valence complex [(OC) 5 Cr 0 -CN-Os III (NH 3 ) 5 ](CF 3 SO 3 ) 2 are measured and analyzed. The excitation profiles (the Raman intensities as a function of excitation wavelength) are obtained using the SO 3 stretch of the triflate ion as an internal standard. The ratios of the Raman intensities are not constant with different excitation wavelengths. This unusual observation is attributed to interference between two overlapping electronic states of the molecule. The electronic states are observed in the low-temperature polarized single crystal absorption spectrum. The resonance Raman intensities and excitation profiles are calculated with the time dependent theory of spectroscopy and include the interference between the electronic states. The origin of the unusual intensities is quantitatively explained in terms of the real and imaginary parts of the Raman cross sections from the two states.

Resonance Raman spectra, a normal coordinate analysis, and calculation of excited-state bond lengths and angles of bis[hydrotris(3,5-dimethyl-1-pyrazolyl)borato]copper(II) are reported. Raman spectra are obtained in resonance with a ligand field state and the lowest ligand-to-metal charge transfer (LMCT) excited state. A normal coordinate analysis is carried out using Raman and IR frequencies and resonance Raman intensities to assist in the assignment of the symmetric modes. Potential energy distributions (PED) and force constants are reported. The individual bond length changes are calculated by using the resonance Raman intensities and the PED. Bond length and angle changes throughout the entire three-dimensional skeleton are reported. The signs of the bond length changes in the pyrazolyl borate ring are interpreted in conjunction with the results of a molecular orbital calculation. The NN bond length decreases by 0.02 Å, the CN bond lengths increase by 0.05 and 0.08 Å, the Cu−N bond increases by 0.10 Å and the NBN angle decreases by 2° in the LMCT excited state.