Bis(dimethyldithiocarbamato)(pyridine)zinc and -copper(II) and their benzene solvates: EPR and solid-state natural abundance (¹³C, ¹⁵N) CP/MAS NMR

Adducts of bis(dimethyldithiocarbamato)zinc and -copper(II) complexes with pyridine, [M(Py)(Mdtc)2], and their benzene solvates [M(Py)(Mdtc)2] · 0.5C6H6 were synthesized. The electron paramagnetic resonance method and solid-state 13C and 15N CP/MAS NMR spectroscopy were used to perform a comparative study of the compounds obtained. The EPR data showed that the geometry of Cu(II) coordination polyhedra both in the adduct itself [Cu(Py)(Mdtc)2], and in its solvate, [Cu(Py)(Mdtc)2] · 0.5C6H6 is intermediate between a square pyramid (SP) and a trigonal bipyramid (TBP), the contribution from the latter being dominant (∼75%) in [Cu(Py)(Mdtc)2]. In the solvated adduct [Cu(Py)(Mdtc)2] · 0.5C6H6, the copper(II) polyhedron is distorted to form an SP-enriched structure (the contribution from TBP is reduced to 55%). It was found NMR data that [Zn(Py)(Mdtc)2] exists in a single high-symmetry molecular form. Coordinated pyridine molecule shows molecular motion about the Zn–N bond. The solvation of the adduct results in structural nonequivalence of the Mdtc–ligands in [Zn(Py)(Mdtc)2] · 0.5C6H6. Signals in the 15N NMR spectra were assigned to the structural positions of the atoms in the previously described molecular structure of a solvated adduct. It was found that the heterogeneous reaction of adduct formation during the absorption of pyridine from the gas phase by polycrystalline [Zn2(Mdtc)4] species is accompanied by the dissociation of binuclear molecules.