Synthesis and characterization of copper(I) complexes of dimethyldipicolinate (dmdp) and X-ray structure of the mononuclear six-coordinate complex [Cu(dmdp) 2]ClO 4

Abstract

Copper(I) salts form with dimethyldipicolinate (dmdp) colored diamagnetic complexes of the type Cu(dmdp)X for X=Cl, Br, I, NCO and N 3 and Cu(dmdp) 2X for X=NO 3 and ClO 4. The complexes are characterized by elemental analysis, IR and electronic spectra. The overall physical measurements suggest that dmdp acts as an O, O, N-tridentate chelating ligand in all these complexes. The 1:2 complexes contain ionic nitrate and perchlorate groups, whereas 1:1 complexes contain bridging halide, azide or cyanate ions. The structure of the mononuclear 1:2 copper(I) perchlorate complex, as determined by single crystal X-ray diffraction, consists of a [Cu(dmdp) 2] + cation and ClO 4 − anion. In the cation, one of the two dmdp molecules coordinates copper(I) by its two carbonyl oxygen and the hetero nitrogen atom whereas the other molecule binds copper(I) via the carbonyl oxygen of one CO 2Me group and the oxygen atom bonded to the methyl of the other CO 2Me group leaving free CO, giving rise to a hexa-coordinate distorted octahedral copper(I) environment. The CuO bonds are variable from 2.318(4) to 2.622(5) Å and the CuN distances are 1.957(5) and 1.974(5) Å.