X‐Ray Photoelectron Spectra of Inorganic Molecules. XIX. Thiocyanato and Isothiocyanato Complexes of the Transition Metals: Carbon 1s, Nitrogen 1s and Sulfur 2p Binding Energies and their Possible Correlation with the Mode of Thiocyanate Bonding

Abstract The X‐ray photoelectron spectra of a series of thiocyanato and isothiocyanato complexes of the transition metals have been recorded. Carbon 1st, nitrogen 1s and sulfur 2p binding energies were measured in order to establish whether there was any clear correlation with the mode of thiocyanate bonding. Complexes which were studied included those possessing M–NCS, M–SCN and M–NCS–M units. In addition, several species were investigated which contained two different thiocyanate environments within the same molecule. These were the ionic complexes [Cu(tren)(NCS)]SCN and [Cu(trien)(SCN)]SCN, where tren = tris(2‐aminoethyl)amine and trien = triethylenetetramine, and Pd(dppe)(NCS)(SCN), where dppe = 1,2‐bis(diphenylphosphino)ethane. The latter complex contains both N‐ and S‐bound thiocyanate. Within the range of complexes studied, the S 2p energies of M–NCS, M–SCN and SCN − differ at most by a few tenths of an electron volt. This indicates that the XPS technique will not usually permit a ready distinction between these different bonding modes in most transition metal complexes.