Role of the trichlorostannyl ligand in homogeneous catalysis. 4. Correlations of solution structure with catalytic activity in cis-[PtCl2(L)(PR3)]/ tin chloride dihydrate (SnCl2O) and [Pt2(.mu.-Cl)2Cl2(PR3)2]/ tin dichloride dihydrate (SnCl2.2H2O)(L = PR3, CO, thioether, amine; R = aryl, alkyl). Olefin hydrogenation and hydroformylation systems