Linear Triplatinum Tetrahydride Complex Supported by Triphosphine Ligands, [Pt 3 (µ‐H) 2 (H) 2 (µ‐dpmp) 2 ](BF 4 ) 2 {dpmp = bis(diphenylphosphinomethyl)phenylphosphine}

By treating [Pt 6 (µ‐H)(H) 2 (µ‐dpmp) 4 ]BH 4 [ 4 , dpmp = bis(diphenylphosphinomethyl)phenylphosphine] with an excess amount of HBF 4 in N , N ‐dimethylformamide (DMF), a triplatinum tetrahydride complex, [Pt 3 (µ‐H) 2 (H) 2 (µ‐dpmp) 2 ](BF 4 ) 2 ( 5 ), was obtained in 51 % yield and was characterized by IR, UV/Vis, 1 H NMR, and 31 P{ 1 H} 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, {Pt 3 (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 1 H{ 31 P} NMR spectroscopy in [D 7 ]DMF revealed that the bridging hydrides exhibit fluxional behavior and migrate along the Pt 3 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 {Pt 3 (µ‐dpmp) 2 } 2+ (Pt 3 II ), which is a building block to construct [Pt 6 (µ‐H)(H) 2 (µ‐dpmp) 4 ] + ( 4 , Pt 3 II Pt 3 II ), formally acts as a four‐electron source to result in [Pt 3 (µ‐H) 2 (H) 2 (µ‐dpmp) 2 ] 2+ ( 5 , Pt 3 VI ) through protonation.