Structural researches on metal complexes of polydentate ligands containing carbonyl and α-diimine moieties. II. Crystal structure of di-μ-thiocyanato-(S,N)-diisothiocyanatobis[2-(2'-pyridyl)-3-(N-2-picolylimino)-4-oxo-1,2,3,4-tetrahydroquinazoline]dicobalt(II)