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/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).

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