FAR INFRA-RED SPECTRA AND FORCE CONSTANTS OF AMMINE COMPLEXES OF PT(4),PT(2) AND PD(2)

Far infra-red spectra of [Pt(NH3)6]4+, [Pt(NH3)4]2+, trans- and cis-[PtCl2(NH3)2], [PtCl3(NH3)]-, cis-[PtBr2(NH3)2], [Pd(NH3)4]2+ and trans-[PdCl2(NH3)2] have been measured in the frequency region down to 60 cm-1. The assignments of the observed bands have been made on the basis of the frequency calculation. The metal-nitrogen in-plane bending vibrations appear in the frequency region from 300 to 200 cm-1 and the metal-nitrogen out-of-plane bending vibrations from 250 to 180 cm-1. For [Pt(NH3)4][PtCl4], [Pt(NH3)4][PtBr4], [Pd(NH3)4][PdCl4] and [Pd(NH3)4][PdBr4], the far infra-red spectra have also been measured and the assignments have been made consistently. The bands appearing around 200 cm-1, which shift to higher frequency region and become strong at liquid nitrogen temperature, are assigned to the A2u lattice vibration having high frequency by the strong metal-metal interaction. The nature of the co-ordination bonds has been discussed on the basis of the force constants obtained. © 1968.