Effect of bulky alkyl substituents on the dynamics and stability of platinum complexes with β-agostic bonding

Abstract

Protonation of the platinum(0) compounds [Pt(CH₂CHBu^t)(P–P)][P–P = Bu^t₂P(CH₂)_nPBu^t₂, n= 2 1a or 3 1b, or Bu^t₂PCH₂C₆H₄CH₂PBu^t₂1c] with HBF₄·OMe₂ in diethyl ether at 273 K afforded the pale yellow cationic complexes [PtH(CH₂CHBu^t){Bu^t₂P(CH₂)₂PBu^t₂}][BF₄]2a and [Pt(C₆H₁₃)(P–P)][BF₄][P–P = Bu^t₂P(CH₂)₃PBu^t₂2b or Bu^t₂PCH₂C₆H₄CH₂PBu^t₂2c] respectively. Complex 2a has been shown by IR and NMR studies to possess a cis alkene–hydride ground-state structure, whilst 2b and 2c achieve a 16-electron configuration via a β-C–H agostic interaction. The reaction between the red dinuclear complex [Pt₂(µ-H)₂(dbpp)₂][BF₄]₂[dbpp = Bu^t₂P(CH₂)₃PBu^t₂] and 2,3,3-trimethylbut-1-ene afforded the complex [Pt(CH₂CHMeBu^t)(dbpp)][BF₄]2d which also exhibits a β-C–H agostic interaction.