Linear Triplatinum Tetrahydride Complex Supported by Triphosphine Ligands, [Pt3(µ‐H)2(H)2(µ‐dpmp)2](BF4)2 {dpmp = bis(diphenylphosphinomethyl)phenylphosphine}

Abstract

By treating [Pt6(µ‐H)(H)2(µ‐dpmp)4]BH4 [4, dpmp = bis(diphenylphosphinomethyl)phenylphosphine] with an excess amount of HBF4 in N,N‐dimethylformamide (DMF), a triplatinum tetrahydride complex, [Pt3(µ‐H)2(H)2(µ‐dpmp)2](BF4)2 (5), was obtained in 51 % yield and was characterized by IR, UV/Vis, 1H NMR, and 31P{1H} NMR spectroscopy in addition to ESI mass spectrometry, X‐ray crystallography, and DFT calculations. Complex 5 is composed of linear trinuclear platinum centers supported by two dpmp ligands, {Pt3(µ‐dpmp)2}6+, which accommodate two terminal and two bridging hydrides in a HPtHPtHPtH zigzag structure. The hydride positions were determined by DFT optimization with B3LYP/GD3BJ functionals. Variable‐temperature 1H{31P} NMR spectroscopy in [D7]DMF revealed that the bridging hydrides exhibit fluxional behavior and migrate along the Pt3 chain by switching the bridging site, whereas the terminal hydrides are not exchanged with the bridging ones. The present results suggest that the divalent linear triplatinum unit of {Pt3(µ‐dpmp)2}2+ (Pt3II), which is a building block to construct [Pt6(µ‐H)(H)2(µ‐dpmp)4]+ (4, Pt3IIPt3II), formally acts as a four‐electron source to result in [Pt3(µ‐H)2(H)2(µ‐dpmp)2]2+ (5, Pt3VI) through protonation.