Microwave Spectrum of Nickel Cyclopentadienyl Nitrosyl and the Configuration of the Molecule

Abstract

THE volatile metallic nitrosyls have long been thought to contain linear (metal—N—O) arrangements, but on the basis of little positive evidence. The electron diffraction studies1 of Co(CO)3NO and Fe(CO)2(NO)2 assume linearity of this grouping, and, while the results are in accord with this, it is not established that a non-linear structure would not fit equally well. The infra-red spectrum of Co(CO)3NO has also been assigned2 on the basis of a linear arrangement, but it is doubtful if such spectra permit the exclusion of other configurations with certainty. It now seems accepted that more than one structure of the nitrosyl group in complexes is possible3, and a bent Co—N—O grouping has been reported4 from the X-ray study of a solid complex. In the case of nickel cyclopentadienyl nitrosyl, C5H5NiNO, moreover, a theoretical treatment of the bonding has been given5, and we have therefore examined the microwave rotational spectrum of this substance.