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
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© 2018 Elsevier Ltd The reaction of (O[dbnd])PH((CH 2 ) 6 CH[dbnd]CH 2 ) 2 (2.0 equiv) and PtCl 2 in toluene gives trans-PtCl 2 (P(OH)((CH 2 ) 6 CH[dbnd]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- [Figure presented] (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[dbnd]CH 2 ) 2 (2.0 equiv) and PtCl 2 in toluene gives cis-PtCl 2 (P(Ph)((CH 2 ) 6 CH[dbnd]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- [Figure presented] (trans-7′), which is a minor product from a published metathesis/hydrogenation sequence involving trans-PtCl 2 (P((CH 2 ) 6 CH[dbnd]CH 2 ) 3 ) 2 , give only cis-7′ as established by 31 P NMR and crystallography.
author list (cited authors)
Stollenz, M., Joshi, H., Ehnbom, A., Fiedler, T., Kharel, S., Reibenspies, J. H., ... Gladysz, J. A.