High Mass Resolution Plasma Desorption and Secondary Ion Mass Spectrometry of Neutral Nickel Thiolate Complexes. Crystal Structure of [Ni₆(SC₃H₇)₁₂]

The use of mass spectrometry for the analysis of transition metal complexes is demonstrated by combined high resolution Plasma Desorption Mass Spectrometry (PDMS) and Secondary Ion Mass Spectrometry (SIMS) investigations of the neutral nickel thiolate complexes [Ni₄(SC₃H₇)8] (1), [Ni₄(SC₆H₁₁)8] (2), [Ni₈(SCH₂COOEt)₁₆] (3) and [Ni₆(SC₃H₇)₁₂] (4). The positive spectra are dominated by three kinds of SI-species: (a) molecular ions, (b) fragment ions and (c) molecular ions with one or more substrate atoms attached. The negative spectra show mainly nickel sulfur cluster ions of the composition (Ni_xS_y)^-. In contrast to many Fast Atom Bombardment (FAB) spectra of neutral metal complexes, SIMS and PDMS spectra provide molecular weight as well as fragment ion information. Both techniques are most powerful tools for the investigation of coordination compounds because the samples are easy to prepare and the spectra are independent of matrix conditions. Additionally crystallographic studies have been carried out for 4. The hexanuclear complex 4 with square planar Ni-S coordination sites crystallizes in the trigonal space group R 3̅ with Z = 3 and α = 18.537(5), c = 13.966(3) Å.