Platinum complexes containing or derived from olefinic phosphines P(X)((CH2)6CHCH2)2 (X = OH, Ph, (CH2)6CHCH2); ring closing metatheses, structures, and trans/cis isomerizations

Abstract The reaction of (O )PH((CH 2 ) 6 CH CH 2 ) 2 (2.0 equiv) and PtCl 2 in toluene gives trans -PtCl 2 (P(OH)((CH 2 ) 6 CH CH 2 ) 2 ) 2 in 68% yield as a 82:18 mixture of Pt–Cl⋯H–OP hydrogen bond isomers. Addition of Grubbs’ first generation catalyst followed by hydrogenation (5 bar, cat. RhCl(PPh 3 ) 3 or PtO 2 ) affords the doubly trans spanning macrocyclic diphosphine adduct trans - (31–9% crude yields). A crystal structure shows that the two OH groups are anti , and hydrogen bond to opposite Cl–Pt–Cl chlorine atoms. The reaction of P(Ph)((CH 2 ) 6 CH CH 2 ) 2 (2.0 equiv) and PtCl 2 in toluene gives cis -PtCl 2 (P(Ph)((CH 2 ) 6 CH CH 2 ) 2 ) 2 ( cis - 5 , 40%) and trans - 5 (8%). The crystal structure of the former is determined. The trans / cis equilibrium ratios of these and related complexes are probed by DFT. Attempts to crystallize trans - ( trans - 7′ ), which is a minor product from a published metathesis/hydrogenation sequence involving trans -PtCl 2 (P((CH 2 ) 6 CH CH 2 ) 3 ) 2 , give only cis - 7′ , as established by 31 P NMR and crystallography.