Tri-aza analogue of an acetylacetonato-complex formed by nucleophilic attack of a co-ordinated nitrile by amidines. X-Ray crystal structure of [Pt{HNC(Ph)NC(Ph)NH}2]·⅔PhMe

Abstract

Lithiobenzamidine reacts with [Pt(PhCN)₂Cl₂], in diethyl ether solution, by attack at the carbon of the co-ordinated nitrile to form [Pt{HNC(Ph)NC(Ph)NH}₂]. The crystal structure, obtained on the golden-yellow platelets of the toluene crystallate, showed a planar molecule having six-membered metallo-ring systems containing three nitrogen atoms. [Pt{HNC(Ph)NC(Ph)NH}₂]·⅔PhMe forms monoclinic crystals [a= 15.468(4), b= 12.576(3), c= 25.206(7)Å, β= 117.64°, space group P2₁/c with six molecules of the complex and four toluenes in each unit cell] in which each planar HNC(Ph)NC(Ph)NH ligand adopts symmetrical σ,σ-attachment through two terminal N atoms The PtN₄unit is planar with a mean Pt–N distance of 1.96 Å. Carbon–nitrogen distances in the ring system are similar, 1.30(7)Å for C–N(C) and 1.36(7)Å for C–N(Pt). This complex is markedly different from the product obtained using lithio-t-butylamidine, LiNHC(Bu)NH, and [Pd(PhCN)₂Cl₂]. The presence of [Pd₃L₄]⁺ ions [L = HNC(Ph)NC(Bu^t)NH] in the mass spectrum and the low solubility of the material suggest a polymeric structure.