Metal–metal bonding in metal–string complexes M3(dpa)4X2 (M = Ni, Co, dpa = di(2-pyridyl)amido, and X = Cl, NCS) from resonance Raman and infrared spectroscopy

Infrared and Raman spectra for metal–string complexes M3(dpa)4X2 (M = Ni, Co, dpa = di(2-pyridyl)amido, and X = Cl, NCS) are studied. We assign the Ni3 asymmetric stretching vibration to infrared lines at 304 and 311 cm−1 for Ni3(dpa)2Cl2 and Ni3(dpa)2(NCS)2, respectively. A Raman shift at 242 cm−1 is assigned to the Ni3 symmetric stretching mode. For Co3 complexes a line for the Co3 asymmetric stretching mode appears at 313 and 331 cm−1 for Co3(dpa)2Cl2 and Co3(dpa)2(NCS)2, respectively.