The structural reorganisation of bis(diethyldithiocarbamato)morpholine-zinc(II) and -copper(II) in the course of solid-state solvation with morpholine and benzene molecules studied by ESR, solid-state C-13 and N-15 CP/MAS NMR spectroscopy and single-crystal X-ray diffraction

Six forms of both non-solvated and solvated adducts of bis(diethyldithiocar bamato)-zine(II) and -copper(II) with morpholine, of general formulas [M{O( CH2)(4)NH} {S2CN(C2H5)(2)}(2)] and [M{O(CH2)(4)NH} {S2CN(C2H5)(2)}(2)].L (M =Zn(II) (1): L= O(CH2)(4)NH (2), C6H6 (3); M = Cu(II) (4): L = O(CH2)(4)NH (5), C6H6 (6)), have been prepared and studied by means of ESR, solid-state natural abundance C-13 and N-15 CP/MAS NMR spectroscopy and single crystal X-ray diffraction data. The existence of two conformers, which are correla ted as rotation isomers, was unambiguously established for both zinc(II) an d copper(II) non-solvated adducts I and 4. These two isomeric forms are cha racterised by different modes of spatial orientation of the non-planar morp holine ring relative to the two four-membered metallochelate rings. The geo metry of the adduct molecules is close to square pyramidal, C-4v, and there fore the ground state of the unpaired copper(II) electron corresponds to th e 3d(x2 - y2) atomic orbital (AO). Solvation of the studied adducts in the solid state leads to their significant structural reorganisation at the mol ecular level, i.e. their structural unification yielding qualitatively new structural states with: (i) different lengths of the Zn-N bond; (ii) reorie nted heterocyclic ring of the coordinated morpholine molecule; and (iii) an enhanced contribution of trigonal-bipyramidal character to the geometry of the coordination polyhedra of the central atom (from 7.5 and 22.7% in orig inal adducts to similar to 75% in solvated forms). The type of geometry of the coordination polyhedrons in the solvated forms of the adducts (intermed iate between trigonal bipyramid D-3h and square pyramid C-4c,) correlates w ith the fact that the ground state of the unpaired copper(II) electron is a mixture of 3d(z2) and 3d(x2 - y2) AOs. All observed ESR and NMR resonances have been assigned and are in agreement with the structures obtained from X-ray diffraction data. (C) 2001 Elsevier Science B.V. All rights reserved.