The composition of Speier's catalyst

It is proposed that the very important and useful “Speier catalyst” contains the complex H[(C3H6)PtCl3] in a solution of isopropyl alcohol. It is this platinum complex which is the active catalyst ingredient in hydrosilylation reactions. When solvent was removed from an “aged” solution of chloroplatinic acid in isopropyl alcohol, the Zeise type dimer, (C3H6)2Pt2Cl4, was deposited as an orange solid. This dimer underwent solvolysis and dissociated into a monomeric species when it dissolved in isopropyl alcohol. Spectroscopic methods involving 195Pt NMR, 1H NMR (360 MHz), far infrared, IR and ESCA were employed in reaching these conclusions.