THE CRYSTAL, MOLECULAR-STRUCTURE AND EPR-SPECTRUM OF DIPOTASSIUM BIS[(MU-ISOTHIOCYANATO-N,S)-(N-SALICYLIDENE-(R)-PHENYLALANINATO)(N-SALICYLIDENE-(S)-PHENYLALANINATO)]-DICUPRATE(II)

The title compound crystallizes in the triclinic system with a space group of P1BAR (No. 2); a = 0.8283(4), b = 0.9477(6), c = 1.2271(5) nm; alpha = 74.251(41), beta = 82.351(34), gamma = 70.475(40)-degrees, V = 0.87282(74) nm3, Z = 1, F(000) = 432, mu = 1.624 mm-1, room temperature. The structure was refined to R = 0.0571 (R(W) = 0.0568) for 1 920 observed reflections. The Cu(II) adopts a distorted square-pyramidal coordination. The base of the coordination polyhedron is formed by O(1), N(1), O(2) donor atoms of the terdentate Schiff-base dianion (sal-(R)-phe or sal-(s)-phe) and N(2) atom of the additional NCS- ligand. The axial site (apical position) of the pyramid is occupied by a weakly bonded S-atom; Cu-S = 0.2995(1) nm, originating from the -NCS- bridging ligands. Two units, [Cu(sal-(R)-phe) (NCS)]- and the corresponding (s)-form, are thus joined into centorsymmetric dicuprate complex anion; [Cu2(mu-isothiocyanato-N,S)2 (sal-(R)-phe)(sal-(s)-phe)]2-. The Q-band EPR spectrum of this complex (powdered sample, room temperature) exhibits orthorhombic g components: g(z) = 2.234, g(y) = 2.059 and g(x) = 2.039 which can be interpreted as molecular ones (G = 4.9).