Synthesis and crystal structure of some (2,2′-dipyridylamine)(carboxylato)(phenoxo)copper(II) complexes with rather unusual phenoxo ligands

Some ternary Cu(dipyam)(OOCR)(OR) complexes (dipyam=2,2′-dipyridylamine; RCOO−=acetate, benzoate, cmb (2-chloro-5-methylthio-benzoate), mta (methylthioacetate), mtn (2-methylthio-nicotinate); OR−=pnp (p-nitrophenolate), dcp (2,6-dichlorophenolate), tcp (2,4,6-trichlorophenolate)) have been synthesized. Their IR spectra are included and the X-ray diffraction structure is given for the crystals of [Cu(dipyam)(OOCCH3)(dcp)] (I), [Cu(dipyam)(mta)(dcp)] (II), [Cu(dipyam)(mtn)(dcp)] (III) and [Cu(dipyam)(cmb)(tcp)] (IV). The copper coordination is square pyramidal in I, with a rather rare axial position of the phenolate ligand, while in II and III is distorted octahedral with equatorial phenolate and weak apical bonds (II Cl, S; III Cl, O). The copper coordination in IV can be better described as square planar, but with distortion toward a flattened tetrahedral geometry and with a rather long apical CuO distance, involving an oxygen of the carboxylate ion. The entrance of the phenolate in an axial or equatorial position is due to the geometry imposed to the complex by the auxiliary ligand.