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.

A tetra-nuclear chlorido-bridged manganese(II) cluster with imidazole ligands.

The crystal structure of di-µ(3)-chlorido-tetra-µ(2)-chlorido-dichloridoocta-(imidazole-κN)tetra-manganese(II) ethanol 1.234 solvate, [Mn(4)Cl(8)(C(3)H(4)N(2))(8)]·1.234C(2)H(5)O or [Mn(4)Cl(8)(Him)(8)]·1.234EtOH, where Him is imidazole (C(3)H(4)N(2)), is based upon two Mn(4)Cl(4) cubes which share one face, and which each lack one manganese vertex, giving a Mn(4)Cl(6) unit. This contains two different octa-hedral coordination environments for the Mn atoms. Mn1 is coordinated by four bridging chlorido ligands and two imidazole N atoms, whereas Mn2 is coordinated by three bridging and one terminal Cl and two imidazole N atoms. The remaining two Mn centres are generated by inversion symmetry. A partial occupancy solvent mol-ecule (ethanol) is present. The crystal structure displays several N-H⋯Cl and N-H⋯O hydrogen bonds.

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

The asymmetric unit of the title compound, (C(4)H(5)N(2)O)(2)[Cu(2)Cl(6)(C(4)H(4)N(2)O)(2)]·2H(2)O, consists of one cation, one half of a centrosymmetric dianion and one water mol-ecule. 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 mol-ecules, 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, (C(4)H(5)N(2)O)(5)[Cd(3)Cl(11)], was obtained from the reaction of 2-hydroxy-pyrimidine hydro-chloride and cadmium(II) chloride in concentrated HCl solution. The crystal structure consists of planar 2-oxo-1,2-dihydro-pyrimidin-3-ium cations with both N atoms protonated and the O atom unprotonated, and a complex trinuclear [Cd(3)Cl(11)](5-) anion of approximately D(3h) symmetry, which has a triangle of three octa-hedrally coordinated Cd(II) centres bonded to 11 chloride ions. Three of the chloride ions bridge adjacent Cd atoms, two cap the faces of the Cd(3) 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, inter-molecular N-H⋯O hydrogen bonds contribute to the formation of a three-dimensional network.

cis-Aqua-dichlorido[pyrimidin-2(1H)-one-κN]copper(II).

In the title compound, [CuCl(2)(C(4)H(4)N(2)O)(H(2)O)], the Cu(II) cation is coordinated by two chloride anions, one pyrimidin-2-one N atom and one water mol-ecule, giving a slightly distorted square-planar geometry. In the crystal structure, the pyrimidin-2-one rings stack along the b axis, with an inter-planar distance of 3.306 Å, as do the copper coordination planes (inter-planar spacing = 2.998 Å). The coordination around the Jahn-Teller-distorted Cu(II) ion is completed by long Cu⋯O [3.014 (5) Å] and Cu⋯Cl [3.0194 (15) Å] inter-actions with adjacent mol-ecules involved in this stacking. Several N-H⋯Cl, O-H⋯Cl and O-H⋯O inter-molecular hydrogen bonds form a polar three-dimensional network.

2,2'-Biimidazolium hexa-aqua-manganese(II) bis-(sulfate).

The title compound, (C(6)H(8)N(4))[Mn(H(2)O)(6)](SO(4))(2), was obtained by cocrystallization of 2,2'-biimidazolium sulfate and bis-(tetra-butyl-ammonium) tetra-chlorido-manganate(II). The asymmetric unit contains one isolated (SO(4))(2-) anion, one half of an octa-hedral [Mn(H(2)O)(6)](2+) dication and one half of a 2,2'-biimidazolium dication, each of which lies on an inversion centre. Mol-ecules are connected by a three-dimensional N-H⋯O and O-H⋯O hydrogen-bond network.

Di-µ-chlorido-bis-[dichlorido(3,3',5,5'-tetra-methyl-4,4'-bipyrazol-1-ium-κN)copper(II)] dihydrate.

The structure of the centrosymmetric title compound, [Cu(2)Cl(6)(C(10)H(15)N(4))(2)]·2H(2)O, consists of a dimeric [{(HMe(4)bpz)CuCl(3)}(2)] unit (HMe(4)bpz is 3,3',5,5'-tetra-methyl-4,4'-bipyrazol-1-ium) with two solvent water molecules. Each [HMe(4)bpz](+) cation is bonded to a CuCl(3) 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.

Coordination chemistry in the solid state: synthesis and interconversion of pyrazolium salts, pyrazole complexes, and pyrazolate MOFs.

Solid pyrazole reacts with HCl gas to form pyrazolium chloride [H2pz]Cl, which reacts in the solid state, under grinding, with metal chlorides MCl2 (M = Co, Zn, Cu) to form the pyrazolium tetrachlorometallate salts [H2pz]2[MCl4] (M = Co 1, Zn 3, Cu 5). Salt 5 cannot be made in solution, and upon standing at room temperature spontaneously emits HCl to give the coordination compound [CuCl2(Hpz)2] (6). Compounds 1 and 3 do not exhibit this behaviour, but can be ground together with bases such as KOH or K2CO3 to effect the elimination of HCl and afford their respective [MCl2(Hpz)2] compounds (M = Co 2, Zn 4). 2, 4 and 6 can also be synthesised in the solid-state by direct reaction of the appropriate metal chloride with pyrazole, or by reaction of a basic metal salt such as the carbonate or hydroxide with pyrazolium chloride. 4 and 6 {and their nickel analogue [NiCl2(Hpz)2]} can be ground with a further two equivalents of base to make the known polymeric metal pyrazolates [M(pz)2]n (M = Ni 7, Cu 8, Zn 9); the same reaction appears to work for the cobalt analogue 2, but the presumed product [Co(pz)2]n10 then decomposes by oxidation. The imidazolate complexes [M(im)2] (M = Ni, 11; Cu, 12; Zn, 13; Co, 14) were similarly prepared by grinding the appropriate [M(Him)2Cl2] precursor with KOH.

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.