Structural and spectroscopic properties of [(CO) 5MM′ (CO) 3(R-DAB)] (M,M′=Mn,Re; R-DAB=1,4-diaza-1,3-butadiene complexes. X-ray structure of [(CO) 5ReMn(CO) 3-(i-Pr-DAB)] and infrared and resonance Raman spectra of [(CO) 5MM′(CO) 3(R-DAB)]

• Published in: Journal of molecular structure 1985-01, Vol.131 (1), p.11-29
• Main Authors: Kokkes, Maarten W., Snoeck, Theo L., Stufkens, Derk J., Oskam, Ad, Cristophersen, Martin, Stam, Casper H.
• Format: Article
• Language: English
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/0022-2860(85)85096-1

The X-ray structure of the title compound has been determined by the heavy-atom method and refined by means of block-diagonal least-squares calculations from 2116 independent reflections. The crystals are monoclinic, space group P2 Vc with unit cell dimensions a = 18.494(3), b = 7.502(2), c = 16.52(2) Å, β = 113.760(6)° and Z = 4. The final R value was 0.037. The complex has an octahedral geometry and the CO ligands of the Re(CO) 3 and Mn(CO) 3(i-Pr-DAB) moieties are in staggered positions. The Mn-Re bond length is 3.012(2) Å and the MnN bond lengths are 1.994(9) and 2.003(9) Å. The infrared and resonance Raman (RR) spectra obtained by excitation into the lowest electronic absorption band, are reported. A tentative assignment for the CO-stretching vibrations is presented based on their solvent and temperature dependence. The RR spectra of (CO) 3MM′(CO) 3(i-Pr-DAB) (M,M′=Mn, Re) taken from N 2-matrices at 10 K are very weak, which means that the equilibrium conformation of these complexes hardly changes upon going from the ground state to the excited state. These RR spectra are discussed considering the electronic structure of these complexes.