[Pt2(dppf)2(μ-S)2] as a heterometallic ligand. Simple assembly of an electroactive interpolymetallic complex [Pt2Tl(dppf)2(μ-S)2]X (X = NO3, PF6) (dppf = 1,1′-bis(diphenylphosphino)ferrocene)

Abstract

Facile complexation of a heterometallic ligand Pt2(dppf)2(μ-S)2 (dppf = 1,1′-bis(diphenylphosphino)ferrocene) with TlNO3 gives [Pt2Tl(dppf)2(μ3-S)2]NO 3, which metathesizes with NH4PF6 to give its PF6 - salt. This Lewis acid-base addition forms the basis of an assembly of electroactive interpolymetallic aggregates which are constituted of an unsaturated fragment of a p-block metal and two redox-active PtII cores, linked by two flexible sulfide bridges. Intermetallics of other metals, viz. Pt2(dppf)2(μ3-S)2InCl3 and [Pt2(dppf)2(μ3-S)2Pb(NO 3)]NO3, are similarly assembled. The X-ray molecular structure of [Pt2Tl(dppf)2(μ3-S)2]PF 6 reveals a side-on attachment of the ligand thereby exposing an "empty space" on the TlI atom. [Pt2Tl{(C5H4PPh2) 2Fe}2(S)2]PF6: a 17.795(4), b 10.553(2), c 17.936(4) Å; monoclinic; P2/n; Z 2. No direct Pt-Tl bonding is envisaged but the close contacts between the two atoms (3.389(1) Å) enable 195P-203/205Tl coupling to be observed in the 195Pt NMR spectrum. The electrochemical behavior of this complex is examined by cyclic voltammetry in 1,2-dichloroethane. The complex undergoes an apparently irreversible two-electron-transfer process of the Tl+ center and a quasi-reversible two-electron-transfer process involving two noninteracting ferrocenyl moieties. © 1995 American Chemical Society.