Mukhtar A. Kurawa

Solid state synthesis of coordination compounds from basic metal salts

The preparation of the complex salts [H2im]2[MCl4] (H2im = imidazolium, M = Co, 1; Zn, 2; Cu, 3) and coordination compounds [MCl2(Him)2] (M = Co, 4; Zn, 5; Cu, 6) by a range of solid-state and solid-gas reactions is reported. Compounds 4–6 and the related [{MCl2(4,4′-bipy)}n] (M = Co, 7; Zn, 8) were prepared by the solid state reactions of metal hydroxide or carbonate salts (or their equivalent) with the hydrochloride salt of the appropriate ligand (imidazole or 4,4′-bipy).

Coordination chemistry of platinum and palladium in the solid-state: synthesis of imidazole and pyrazole complexes.

Solid-state reactions of palladium(II) and platinum(II) chloride complexes with imidazole (Him) and pyrazole (Hpz) or their hydrochloride salts are shown to produce metal complex salts and coordination compounds. Thus, K(2)[MCl(4)] or MCl(2) can be ground with imidazolium chloride ([H(2)im]Cl) to produce the salts [H(2)im](2)[MCl(4)] (M = Pd, 1; Pt, 5), which can then be dehydrochlorinated in the solid state to produce the coordination compounds trans-[PdCl(2)(Him)(2)] 3 or cis-[PtCl(2)(Him)(2)] 6. The complex cis-[PdCl(2)(Him)(2)] 2 is produced when Pd(OAc)(2) is ground with [H(2)im]Cl. Reaction of platinum chloride reagents with imidazole (Him) also produces cis-[PtCl(2)(Him)(2)] 6, but reaction of imidazole with analogous palladium chloride reagents first produces [Pd(Him)(4)]Cl(2) 4 which then slowly converts to trans-[PdCl(2)(Him)(2)] 3. Grinding pyrazolium chloride with K(2)[MCl(4)] produces [H(2)pz](2)[MCl(4)] (M = Pd, 7; Pt, 10), which may also be dehydrochlorinated in the solid state to produce the coordination compounds trans-[PdCl(2)(Hpz)(2)] 8 or cis-[PtCl(2)(Hpz)(2)] 11. Grinding K(2)[PdCl(4)] or PdCl(2) with pyrazole gives [Pd(Hpz)(4)]Cl(2) 9, which is then slowly converted into trans-[PdCl(2)(Hpz)(2)] 8. Grinding PtCl(2) with Hpz generates [Pt(Hpz)(4)]Cl(2) 12, but using K(2)PtCl(4) as the metal source does not generate the same product. The single-crystal structures of 8, a new polymorph of 11 and [H(2)pz](2)[PtCl(6)].2H(2)O (isolated as a decomposition product) are reported for the first time, and the structures of 5 and 10 have been solved ab ibitio from XRPD data.

Coordination Chemistry in the Solid State: Reactivity of Manganese and Cadmium Chlorides with Imidazole and Pyrazole and Their Hydrochlorides

Crystalline coordination compounds [MnCl(2)(Hpz)(2)] 3, [CdCl(2)(Hpz)(2)] 5, [MnCl(2)(Him)(2)] 9, and [CdCl(2)(Him)(2)] 13 (Him = imidazole; Hpz = pyrazole) can be synthesized in solid state reactions by grinding together the appropriate metal chloride and 2 equiv of the neutral ligand. Similarly, grinding together the metal chlorides with the ligand hydrochloride salts produces the halometallate salts [H(2)pz][MnCl(3)(OH(2))] 1, [H(2)pz][CdCl(4)] 4, [H(2)im](6)[MnCl(6)][MnCl(4)] 8, and [H(2)im](6)[CdCl(6)][CdCl(4)] 11. In contrast, reacting the metal chloride salt with the ligand in concentrated HCl solution yields a second set of salts [H(2)pz][MnCl(3)] 2, [H(2)im][MnCl(3)(OH(2))(2)] 7, and [H(2)im][CdCl(3)(OH(2))]·H(2)O 12. Compound 5 can be partly dehydrochlorinated by grinding with KOH to form an impure sample of the pyrazolate compound [Cd(pz)(2)] 6, while recrystallizing 9 from ethanol yielded crystals of solvated [Mn(4)Cl(8)(Him)(8)] 10. The crystal structure determinations of 1, 2, 4, 11, and 12 are reported.

2-Oxo-1,2-dihydro­pyrimidin-3-ium di-μ-chlorido-bis­{dichloridobis[pyrimidin-2(1H)-one-κN3]cuprate(II)} dihydrate

The asymmetric unit of the title compound, (C4H5N2O)2[Cu2Cl6(C4H4N2O)2]·2H2O, consists of one cation, one half of a centrosymmetric dianion and one water molecule. The centrosymmetric dianion formed by dimerization in the crystal structure has neutral pyrimidin-2-one ligands coordinated to each copper(II) centre through Cu—N bonds. The Cu atoms each have a distorted trigonal bipyramidal geometry, with the N atom of the pyrimidin-2-one ligand in an axial position, and dimerize by sharing two equatorial Cl atoms. N—H⋯Cl, O—H⋯Cl and N—H⋯O hydrogen bonds connect the anions, cations and water molecules, forming a three-dimensional network.

Penta-kis(2-oxo-2,3-dihydro-pyrimidin-1-ium) di-μ(3)-chlorido-tri-μ(2)-chlorido-hexa-chloridotricadmate(II).

The title compound, (C4H5N2O)5[Cd3Cl11], was obtained from the reaction of 2-hydroxypyrimidine hydrochloride and cadmium(II) chloride in concentrated HCl solution. The crystal structure consists of planar 2-oxo-1,2-dihydropyrimidin-3-ium cations with both N atoms protonated and the O atom unprotonated, and a complex trinuclear [Cd3Cl11]5− anion of approximately D 3h symmetry, which has a triangle of three octahedrally coordinated CdII centres bonded to 11 chloride ions. Three of the chloride ions bridge adjacent Cd atoms, two cap the faces of the Cd3 triangle and the remaining six are terminally bonded and act as hydrogen-bond acceptors. Various N—H⋯Cl hydrogen bonds connect the anions and cations and, in addition, intermolecular N—H⋯O hydrogen bonds contribute to the formation of a three-dimensional network.

Pentakis(2-oxo-2,3-dihydropyrimidin-1-ium) di-μ 3 -chlorido-tri-μ 2 -chlorido-hexacholoridotricadmate(II)

The title compound, (C4H5N2O)5[Cd3Cl11], was obtained from the reaction of 2-hydroxypyrimidine hydrochloride and cadmium(II) chloride in concentrated HCl solution. The crystal structure consists of planar 2-oxo-1,2-dihydropyrimidin-3-ium cations with both N atoms protonated and the O atom unprotonated, and a complex trinuclear [Cd3Cl11]5− anion of approximately D 3h symmetry, which has a triangle of three octahedrally coordinated CdII centres bonded to 11 chloride ions. Three of the chloride ions bridge adjacent Cd atoms, two cap the faces of the Cd3 triangle and the remaining six are terminally bonded and act as hydrogen-bond acceptors. Various N—H⋯Cl hydrogen bonds connect the anions and cations and, in addition, intermolecular N—H⋯O hydrogen bonds contribute to the formation of a three-dimensional network.

Di-μ-chlorido-bis­[dichlorido(3,3′,5,5′-tetra­methyl-4,4′-bipyrazol-1-ium-κN2′)copper(II)] dihydrate

The structure of the centrosymmetric title compound, [Cu2Cl6(C10H15N4)2]·2H2O, consists of a dimeric [{(HMe4bpz)CuCl3}2] unit (HMe4bpz is 3,3′,5,5′-tetramethyl-4,4′-bipyrazol-1-ium) with two solvent water molecules. Each [HMe4bpz]+ cation is bonded to a CuCl3 unit through a Cu—N dative bond, effectively making square-planar geometry at the Cu atom. Two of these units then undergo a face-to-face dimerization so that the Cu atoms have a Jahn–Teller distorted square-pyramidal geometry with three chlorides and an N atom in the basal plane and one chloride weakly bound in the apical position. Several N—H⋯Cl, O—H⋯Cl and N—H⋯O hydrogen bonds form a three-dimensional network.

cis-Aqua­dichlorido[pyrimidin-2(1H)-one-κN 3]copper(II)

In the title compound, [CuCl2(C4H4N2O)(H2O)], the CuII cation is coordinated by two chloride anions, one pyrimidin-2-one N atom and one water molecule, giving a slightly distorted square-planar geometry. In the crystal structure, the pyrimidin-2-one rings stack along the b axis, with an interplanar distance of 3.306 Å, as do the copper coordination planes (interplanar spacing = 2.998 Å). The coordination around the Jahn–Teller-distorted CuII ion is completed by long Cu⋯O [3.014 (5) Å] and Cu⋯Cl [3.0194 (15) Å] interactions with adjacent molecules involved in this stacking. Several N—H⋯Cl, O—H⋯Cl and O—H⋯O intermolecular hydrogen bonds form a polar three-dimensional network.