Issue 18, 1992

Platinum ethyl complexes with β-agostic Pt–H–C bonding

Abstract

Protonation with non-co-ordinating acids of the complexes [Pt(η2-C2H4)(L–L)][L–L =(H11C6)2P(CH2)2P(C6H11)2, 1a, But2P(CH2)2PBut2, 1b, (H11C6)2P(CH2)3P(C6H11)2, 1c, But2P(CH2)3PBut2, 1d or o-But2PCH2C6H4CH2PBut2, 1e] and [PtEt2(L–L)]2a2d affords a series of cationic platinum(II) complexes 3a3e which in the case of 3a3c adopt a cis ethene/hydride ground state whereas in 3d and 3e the otherwise electron-deficient metal centre is stabilized by a two-electron, three-centre agostic interaction with the β-CH bond of the ethyl ligand. Complexes 13 were characterized by 1H, 13C and 31P NMR spectroscopy and for 2d and 3d by single-crystal X-ray crystallography. The influence of the chelating diphosphine ligand on the strength of the agostic bond was monitored by NMR spectroscopy. This revealed that the cations undergo two fluxional processes in solution: (a) agostic methyl rotation and (b)β-elimination/ethene rotation, a combination of which scrambles all five protons and both carbon atoms of the ‘C2H5’ moiety. The 31P nuclei, however, remain inequivalent at temperatures up to 300 K. The agostic interaction was displaced by a small two-electon donor molecule L to form the series of adducts [PtEt(L)(L–L)]+(L = acetonitrile or pyridine) in which the ‘normal’ ethyl complex is the first formed species. The adducts are unstable to loss of C2H4 by β-elimination to form the series of cationic hydrides [PtH(L)(L–L)]+. For comparison, the complex [PtH(O3SCF3){But2P(CH2)3PBut2}] was synthesised and characterized by 1H and 31P NMR spectroscopy and X-ray crystallography.

Article information

Article type
Paper

J. Chem. Soc., Dalton Trans., 1992, 2653-2662

Platinum ethyl complexes with β-agostic Pt–H–C bonding

N. Carr, L. Mole, A. G. Orpen and J. L. Spencer, J. Chem. Soc., Dalton Trans., 1992, 2653 DOI: 10.1039/DT9920002653

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Spotlight

Advertisements