Treatment of o-(diphenylphosphino)aniline with 3-formylacetylacetone led to the formation of the ketimine type Schiff base 3-((o-diphenylphosphino-phenylamino)-methylene)-pentane-2,4-dione (oÀ PPh 2 À C 6 H 4 À NHÀ CH=C(COCH 3 ) 2 , HL). Complexes [ML 2 ] (M = Fe, Co, Ni, Cu) were obtained from the reaction of HL with the corresponding metal acetate or acetylacetonate derivatives. The [ML 2 ] complexes (M = Fe, Co, Ni) exhibit a distorted octahedral coordination from two tridentate P,N,O ketiminate ligands L À . The arrangement of the ligands is meridional in the case of [FeL 2 ] and [NiL 2 ] . The cobalt complex [CoL 2 ] displays a facial coordination. In the case of the nearly square planar copper complex [CuL 2 ], only the ketiminate functionalities of the ligands are involved in coordination and the participation of the PPh 2 groups is neglectable.