Functionalization of η12-Bridging Cyaphide (C≡P)- Ligands: Trinuclear η112-Bridging Cyaphide and Dinuclear Bridging Isocyaphide (C≡PR) Complexes of Platinum

Wayde V. Konze, Victor G. Young, Robert J. Angelici

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Abstract

The oxidative addition reaction of Pt(PEt3)4 with Cl2C=PN(SiMe3)2 at low temperature (-50 °C) forms the η1-phosphavinyl complex cis-Cl(Et3P)2Pt[C(Cl)=PN(SiMe3)2] (Ia), which isomerizes to the trans-isomer (Ib) upon warming to 0 °C; the structure of Ib was determined by X-ray diffraction studies. Complex Ib reacts with Pt(PEt3)2Cl2 in the presence of 3 equiv of sodium benzophenone to generate the bridging, dinuclear η12-cyaphide complex Cl(Et3P)2-Pt(μ-η12-C≡P)Pt(PEt3)2 (II) in good yield, providing a much simpler and higher yield preparation of II, which was synthesized and characterized previously by a more circuitous route. Compound II reacts with 0.5 equiv of [Cl2Pt(PEt3)]2 or with 1 equiv of W(CO)5(THF) to generate the trinuclear metal-cyaphide complexes Cl(Et3P)2Pt[μ-η112-C≡P{Pt(PEt3)-(Cl) 2}]Pt(PEt3)2 (III) and Cl(Et3P)2Pt[μ-η112-C≡P{W(CO)5}]Pt(PEt 3)2 (IV), respectively, in which the lone pair of electrons on the C≡P phosphorus atom is coordinated to a Pt-(PEt3)(Cl)2 fragment in the former and to a W(CO)5 fragment in the latter; the structure of IV was determined by X-ray diffraction studies. Compound II also reacts with MeI to form the methyl isocyaphide complex (Cl)(Et3P)Pt(μ-C=PMe)Pt(PEt3)2(I) (Vc), in which the cyaphide (C≡P-) ligand is converted to a methyl isocyaphide (C≡PMe) ligand in a semibridging coordination mode. When compound II is reacted with MeOTf, the product is the cationic isocyaphide complex [(Cl)(Et3P)2Pt(μ-η12-C≡PMe)Pt(PEt3)2](OTf) (Va), which is likely coordinated in an η12-bridging mode. Compound Va reacts with NaI to form Vc, which suggests that Va forms as an intermediate before Vc in the reaction of II with MeI. † Dedicated to Professor Helmut Werner on the occasion of his 65th birthday.

Original languageEnglish (US)
Pages (from-to)258-267
Number of pages10
JournalOrganometallics
Volume18
Issue number2
DOIs
StatePublished - Jan 18 1999

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