Crystal structures of two copper(I)–6,6′-dimethyl-2,2′-bipyridyl (dmbpy) compounds, [Cu(dmbpy)(2)](2)[MF(6)]·xH(2)O (M = Zr, Hf; x = 1.134, 0.671)

The syntheses and crystal structures of two bimetallic mol­ecular compounds, namely, bis[bis­(6,6′-dimethyl-2,2′-bi­pyridine)­copper(I)] hexa­fluorido­zir­con­ate(IV) 1.134-hydrate, [Cu(dmbpy)(2)](2)[ZrF(6)]·1.134H(2)O (dmbpy = 6,6′-di­methyl-2,2′-bipyri­dyl, C(12)H(12)N(2)), (I), and bis[bis­(6,6′-dimethyl-2,2′-bi­pyr­idine)­copper(I)] hexa­fluorido­hafnate(IV) 0.671-hydrate, [Cu(dmbpy)(2)](2)[HfF(6)]·0.671H(2)O, (II), are reported. Apart from a slight site occupany difference for the water mol­ecule of crystallization, compounds (I) and (II) are isostructural, featuring isolated tetra­hedral cations of copper(I) ions coordinated by two dmbpy ligands and centrosymmetric, octa­hedral anions of fluorinated early transition metals. The tetra­hedral environments of the copper complexes are distorted owing to the steric effects of the dmbpy ligands. The extended structures are built up through Coulombic inter­actions between cations and anions and π–π stacking inter­actions between heterochiral Δ- and Λ-[Cu(dmbpy)(2)](+) complexes. A comparison between the title compounds and other [Cu(dmbpy)(2)](+) compounds with monovalent and bivalent anions reveals a significant influence of the cation-to-anion ratio on the resulting crystal packing architectures, providing insights for future crystal design of distorted tetra­hedral copper compounds.