Single-crystal electronic spectra of a NiPI3 chromophore

Single-crystal polarized spectra of tetraphenylarsonium triiodo(triphenylphosphine)nickelate(II), [(C6H5)4As][NiI3{P(C 6H5)3}], have been recorded between 380 and 77°K. The NiPI3 chromophore has an approximate C3υ symmetry; however, the observed polarization properties cannot be accounted for by axial symmetry. The band intensities are found to be temperature dependent. This has been discussed on the basis of a temperature dependent population of levels arising from low symmetry and spin-orbit coupling effects on the 3E ground level.