Crystal structure of (4,4′-bipyridyl-κN)bis­[N-(2-hydroxy­ethyl)-N-iso­propyl­dithio­carbamato-κ(2) S,S′]zinc(II)–4,4′-bipyridyl (2/1) and its isostructural cadmium(II) analogue

The title structures, [M(C(6)H(12)NOS(2))(2)(C(10)H(8)N(2))]·0.5C(10)H(8)N(2), for M = Zn, (I), and Cd, (II), feature terminally bound 4,4′-bipyridyl ligands and non-coordinating 4,4′-bi­pyridyl mol­ecules, with the latter disposed about a centre of inversion. The coordination geometry about the metal atom is defined by two non-symmetrically chelating di­thio­carbamate ligands and a pyridyl N atom. The NS(4) donor sets are distorted but, approximate to trigonal bipyramidal in each case. In the crystal, hy­droxy-O—H⋯O(hy­droxy) and hy­droxy-O—H⋯N(pyrid­yl) hydrogen bonds between the zinc-containing mol­ecules lead to a supra­molecular layer parallel to (100). The three-dimensional architecture arises as the layers are linked via methine-C—H⋯S, pyridyl-C—H⋯O(hy­droxy) and π–π [inter-centroid distance between coordinated pyridyl rings = 3.6246 (18) Å] inter­actions. Channels along the c-axis direction are occupied by the non-coordinating 4,4′-bipyridine mol­ecules, which are held in place by C—H⋯π(chelate ring) contacts.