Iso-propyl-ammonium halidometallates. I. [CoX (4)](2-)·X (-) (X = Cl, Br), ZnCl(4) (2-), and [ZnCl(3) (-)] (n) salts.

An exploration of the iso-propyl-ammonium (IPA(+)) metal halide structural space is conducted, initially, for cobalt(II) and zinc(II) halides as a counterpart to the more extensively studied metal halide systems containing the isomeric tri-methyl-ammonium cation. For cobalt(II) halides, the only compound obtained from slow evaporation of acidic aqueous solutions of iso-propyl-ammonium halide and cobalt(II) halide is (IPA(+))(3)CoX (4)·X (X = Cl, Br), namely, tris-(iso-propyl-ammonium) tetra-chlorido-cobaltate(II) chloride, (C(3)H(10)N)(3)[CoCl(4)]Cl, and tris-(iso-propyl-ammonium) tetra-bromido-cobaltate(II) bromide, (C(3)H(10)N)(3)[CoBr(4)]Br, regardless of the starting stoichiometric ratio of (IPA(+))X:CoX (2). These structures consist of isolated tetra-hedral CoX (4) (2-) complexes and X (-) ions separated by IPA(+) cations. One IPA(+) cation hydrogen bonds to two complexes and to two halide ions to produce clusters. These clusters form stacks with hydrogen bonding from the remaining IPA(+) cations linking the stacks into a tight, three-dimensional network. A 2:1 molar ratio of (IPA(+))Cl and ZnCl(2) under similar growth conditions readily yields crystals of bis-(iso-propyl-ammonium) tetra-chlorido-zincate(II), (C(3)H(10)N)(2)[ZnCl(4)] or (IPA(+))(2)ZnCl(4), consisting only of IPA(+) cations and isolated ZnCl(4) (2-) tetra-hedra. This despite the expectation of common structural chemistry for the similarly sized Co(2+) and Zn(2+) ions with 51 known isostructural A(2)CoCl(4) and A(2)ZnCl(4) compounds out of 54 for the same monopositive A cation. Growth from a 1:1 ratio of (IPA(+))Cl:ZnCl(2) yields crystals of poly[iso-propyl-ammonium [[di-chlorido-zincate(II)]-μ-chlorido]], {(C(3)H(10)N)[ZnCl(3)]} (n) or (IPA(+))ZnCl(3), in which parallel chains of corner-sharing ZnCl(4) tetra-hedra are separated by IPA(+) cations. This unusual zinc(II) halide chain structure has previously been observed only in [YCH(2)(CH(3))(3)N]ZnCl(3) salts (Y = H, halogen). In contrast to these known compounds, which are found in polar ortho-rhom-bic space groups, the structure reported here is in ortho-rhom-bic Pbca.