Synthesis, spectroscopic study and X-ray crystal structure of unsymmetrical bis(phosphine)-platinum complex, <f>[PtCl<sub>2</sub>{η<sup>2</sup>-Ph<sub>2</sub>POCH<sub>2</sub>CH<sub>2</sub>N(CH<sub>3</sub>)PPh<sub>2</sub>]</f>