On the reactivity of platina‐β‐diketones: a straightforward synthesis of trans ‐acetylchlorobis(phosphine)platinum(II) complexes and their reactivity

The platina‐β‐diketone [Pt 2 {(COMe) 2 H} 2 (µ‐Cl) 2 ] ( 1 ) was found to react with monodentate phosphines to yield acetyl(chloro)platinum(II) complexes trans ‐[Pt(COMe)Cl(PR 3 ) 2 ] (PR 3 = PPh 3 , 2a ; P(4‐FC 6 H 4 ) 3 , 2b ; PMePh 2 , 2c ; PMe 2 Ph, 2d ; P( n ‐Bu) 3 , 2e ; P( o ‐tol) 3 , 2f ; P( m ‐tol) 3 , 2g ; P( p ‐tol) 3 , 2h ). In the reaction with P( o ‐tol) 3 the methyl(carbonyl)platinum(II) complex [Pt(Me)Cl(CO){P( o ‐tol) 3 }] ( 3a ) was found to be an intermediate. On the other hand, treating 1 with P(C 6 F 5 ) 3 led to the formation of [Pt(Me)Cl(CO){P(C 6 F 5 ) 3 }] ( 3b ), even in excess of the phosphine. Phosphine ligands with a lower donor capability in complexes 2 and the arsine ligand in trans ‐[Pt(COMe)Cl(AsPh 3 ) 2 ] ( 2i ) proved to be subject to substitution by stronger donating phosphine ligands, thus forming complexes trans ‐[Pt(COMe)Cl(L)L′] (L/L′ = AsPh 3 /PPh 3 , 4a ; PPh 3 /P( n ‐Bu) 3 , 4b ) and cis ‐[Pt(COMe)Cl(dppe)] ( 4c ). Furthermore, in boiling benzene, complexes 2a – 2c and 2i underwent decarbonylation yielding quantitatively methyl(chloro)platinum(II) complexes trans ‐[Pt(Me)Cl(L) 2 ] (L = PPh 3 , 5a ; P(4‐FC 6 H 4 ) 3 , 5b ; PMePh 2 , 5c ; AsPh 3 , 5d ). The identities of all complexes were confirmed by 1 H, 13 C and 31 P NMR spectroscopy. Single‐crystal X‐ray diffraction analyses of 2a ·2CHCl 3 , 2f and 5b showed that the platinum atom is square‐planar coordinated by two phosphine ligands (PPh 3 , 2a ; P( o ‐tol) 3 , 2f ; P(4F‐C 6 H 4 ) 3 , 5b ) in mutual trans position as well as by an acetyl ligand ( 2a, 2f ) and a methyl ligand ( 5b ), respectively, trans to a chloro ligand. Single‐crystal X‐ray diffraction analysis of 3b exhibited a square‐planar platinum complex with the two π‐acceptor ligands CO and P(C 6 F 5 ) 3 in mutual cis position (configuration index: SP ‐4‐3). Copyright © 2005 John Wiley & Sons, Ltd.