Spectroscopic studies of temperature induced phase transitions in metal-organic complex trans-PtCl2(PEt3)2.

Abstract

Tuning of molecular and electronic properties of Pt(II)-organic complexes have a profound effect on their applications in the fields of technology, pharmaceuticals and crystal engineering. Here, we present combined infrared and Raman spectroscopic investigations on trans-PtCl2(PEt3)2 systematically carried out at various temperatures from 300 to 4.2 K in a wide spectral range. The studies suggest drastic orientational changes of different moieties around 180 K and 130 K in the ligand groups attached to the central Pt atom. This is accompanied by a systematic strengthening of C-H⋯Cl hydrogen bonds in the 180-130 K temperature range. A discontinuous change in intensity, peak variations of modes and emergence of new modes across 180 K and 130 K in the lattice region are suggestive of a possible structural phase transition. It is interesting to note that the spectral signatures of the low temperature phase are different from those reported recently for the high pressure phase in this compound. These studies will be useful in better understanding the physico-chemical properties of metal-organic complexes in order to exploit their applications in various bio-chemical and technological fields.