Construction of Copper(I) Coordination Polymers of 1,2,4,5-Tetracyanobenzene with Zigzag Sheet and Porous Frameworks

Computational screening of structural and compositional factors for electrically conductive coordination polymers

We test a range of building blocks and connectivity for the construction of electroactive metal–organic frameworks.

Variable coordination of redox-active TCNB in discrete and polymeric ferrocenylcopper(I) complexes: structures and spectroelectrochemical behaviour

1,2,4,5-Tetracyanobenzene (TCNB) was reacted with [Cu(dppf)(CH3CN)2](BF4) and [Cu(dchpf)(CH3CN)](BF4), dppf = 1,1'-bis(diphenylphosphino)ferrocene and dchpf = 1,1'-bis(dicyclohexylphosphino)ferrocene, to produce a heterotetranuclear metallamacrocycle 1, {[Cu(dppf)(μ-TCNB)](BF4)}2, and a heterooctanuclear complex 2, [{Cu(dchpf)}4(μ4-TCNB)](BF4)4. Complex 1 is the first example of a structurally characterised discrete transition metal complex of TCNB. Upon crystallisation attempts, compound 2 formed the structurally identified coordination polymer 3, {[Cu(dchpf)(μ-TCNB)]2(BF4)2}n. Structural and spectroscopic analyses confirmed the redox-innocent behaviour of TCNB in 1, 2 and 3. However, the soluble compounds 1 and 2 could be oxidised and reduced spectroelectrochemically (UV-vis, IR, and EPR). The oxidation occurs invariably at the ferrocene sites without notable splitting of redox potentials. Reduction involves the TCNB bridging ligands to produce radical complexes. As a variably bridging acceptor component of supramolecular structures the TCNB ligand thus adopts an intermediate position between the highly electron transfer-active TCNE, TCNQ and TCNQF4 systems and the numerous redox-innocent bridges.

One-dimensional hydrogen-bonded infinite chain from nickel(II) tetraaza macrocyclic complex and 1,2-cyclopentanedicarboxylate ligand

The reaction of [Ni(L)]Cl(2)·2H(2)O (L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo [14,4,0(1.18),0(7.12)]docosane) with trans-1,2-cyclopentanedicarboxylic acid (H(2)-cpdc) yields a 1D hydrogen-bonded infinite chain with formula [Ni(L)(H-cpdc(-))(2)] (1). This complex has been characterized by X-ray crystallography, spectroscopy and cyclic voltammetry. The crystal structure of 1 exhibits a distorted octahedral geometry about Ni atom with four nitrogen atoms of the macrocycle and two oxygen atoms of the H-cpdc(-) ligand at the axial position. Compound 1 crystallizes in the monoclinic system P2(1)/c with a = 8.7429(17), b = 10.488(2), c = 18.929(4) Å, β = 91.82(2), V = 1734.8(6) Å(3), Z = 2. Electronic spectrum of 1 reveals a high-spin octahedral environment. Cyclic voltammetry of 1 undergoes two waves of a one-electron transfer corresponding to Ni(II)/Ni(III) and Ni(II)/Ni(I) processes.

Organometallic Silver(I) Supramolecular Complexes Generated from Multidentate Furan-Containing Symmetric and Unsymmetric Fulvene Ligands and Silver(I) Salts

One new conjugated symmetric fulvene ligand L1 and two new unsymmetric fulvene ligands L2 and L3 were synthesized. Five new supramolecular complexes, namely Ag2(L1)3(SO3CF3)3 (1) (1, monoclinic, P2(1)/c; a = 12.702(3) A, b = 26.118(7) A, c = 13.998(4) A, beta = 96.063(4) degrees, Z = 4), [Ag(L1)]ClO4 (2) (monoclinic, C2/c; a = 17.363(2) A, b = 13.2794(18) A, c = 13.4884(18) A, beta = 100.292(2) degrees, Z = 8), [Ag(L1)(C6H6)SbF6] x 0.5C6H6 x H2O (3) (monoclinic, P2(1)/c; a = 6.8839(11) A, b = 20.242(3) A, c = 18.934(3) A, beta = 91.994(3) degrees, Z = 4), Ag(L2)(SO3CF3) (4) (triclinic, P1; a = 8.629(3) A, b = 10.915(3) A, c = 11.178(3) A, alpha = 100.978(4) degrees, beta = 91.994(3) degrees, gamma = 105.652(4) degrees, Z = 2), and Ag(L3)(H2O)(SO3CF3) (5) (triclinic, P1; a = 8.914(5) A, b = 10.809(6) A, c = 11.283(6) A, alpha = 69.255(8) degrees, beta = 87.163(9) degrees, gamma = 84.993(8) degrees, Z = 2) were obtained through self-assembly based on these three new fulvene ligands in a benzene/toluene mixed-solvent system. Compounds 1-5 have been fully characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. The results indicate that the coordination chemistry of new fulvene ligands is versatile. They can adopt either cis- or trans-conformation to bind soft acid Ag(I) ion through not only the terminal -CN and furan functional groups but also the fulvene carbon atoms into organometallic coordination polymers or discrete complexes. In addition, the luminescent properties of L1-L3 and their Ag(I) complexes were investigated preliminarily in EtOH and solid state.

A Three-Dimensional, Noninterpenetrating Metal−Organic Framework with the Moganite Topology: A Simple (42.62.82)(4.64.8)2Net Containing Two Kinds of Topologically Nonequivalent Points

Self assembly of Cu(2+) with the multifunctional ligand 2-(4-pyridyl)thiazole-4-carboxylic acid (Pytac) affords the neutral 3D coordination polymer [Cu(3)(Pytac)(6)](H(2)O)(14) (hereafter, SZL-1), which has the rare moganite topology. The mineral moganite has a topology that is closely related to the well-known quartz topology, but the two topologies are differentiated by the number of topologically inequivalent nodes. Whereas only one kind of node is present in quartz, two types of topologically inequivalent nodes are present in moganite. The title compound, which has three vertices in its repeat unit, has two types of topologically inequivalent nodes with the overall vertex symbol (4(2)x6(2)x8(2))(4x6(4)x8)(2) corresponding to the moganite net. Prior to this report, few metal-organic framework materials (MOFs) have been found to contain more than one type of node, and SZL-1 is the first MOF with the moganite topology.

Reactivity of Pyridine-2,4,6-tricarboxylic Acid toward Zn(II) Salts under Different Reaction Conditions

Pyridine-2,4,6-tricarboxylic acid (ptcH(3)) readily reacts with a Zn(II) salt at room temperature to form different products depending upon the presence or absence of pyridine in the reaction mixture. In the presence of pyridine, the ligand breaks to form infinitely zigzag coordination polymers with the empirical formula [Zn(Ox)(py)(2)]n(Ox = oxalate, py = pyridine). The backbone is formed from Zn(II)-oxalate where two pyridine molecules are coordinated to each Zn(II) ion giving it hexacoordination. The orientation of the bound pyridines is slightly different when Zn(II)-nitrate is used compared to that when Zn(II)-sulfate (or acetate) salt is used. In absence of pyridine, the ligand remains intact and forms a mixture of a carboxylate-bridged coordination polymer and a discrete carboxylate-bridged 12-membered metallomacrocycle.

New Ag(I)-Containing Coordination Polymers Generated from Multidentate Schiff-Base Ligands

The coordination chemistry of the multidentate Schiff-base ligands 2,5-bis(3-methylpyrazinyl)-3,4-diaza-2,4-hexadiene (L5) and 2,5-bis(pyrazinyl)-3,4-diaza-2,4-hexadiene (L6) with inorganic Ag(I) salts has been investigated. Six new Ag(I)-coordination polymers were prepared by solution reactions and fully characterized by infrared spectroscopy, elemental analysis, thermogravimetric analysis, and single-crystal X-ray diffraction. [Ag(L5)]ClO(4).0.5CH(3)OH (1, orthorhombic, Fdd2; a = 20.0896(11) A, b = 48.224(3) A, c = 7.8432(4) A, Z = 16), [Ag(L5)]PF(6).0.5CH(3)OH (2, orthorhombic, Fdd2; a = 20.7255(11) A, b = 46.166(2) A, c = 8.4332(4) A, Z = 16), [Ag(L5)]SbF(6).0.5CH(3)OH (3, orthorhombic, Fdd2; a = 21.5481(11) A, b = 45.196(2) A, c = 8.7331(4) A, Z = 16), and [Ag(L5)](BF(4)).0.5CH(3)OH (4, orthorhombic, Fdd2; a = 19.8897(11) A, b = 48.358(3) A, c = 7.7491(5) A, Z = 16) were obtained by combination of L5 with AgClO(4).xH(2)O, AgPF(6), AgSbF(6), and AgBF(4), respectively, in a methylene chloride/methanol mixed solvent system. Compounds 1-4 are isostructural and feature noninterpenetrating three-dimensional zeolite-like networks. [Ag(4)(L6)(4)](PF(6))(4).CHCl(3) (5, tetragonal, Pc2; a = 16.1067(3) A, b = 16.1067(3) A, c = 14.4935(5) A, Z = 2) was generated from the reaction of L6 with AgPF(6) in a chloroform/ethanol mixed solvent system. It forms with a unique one-dimensional nanometer-tube that can be considered a new polymeric motif based on the [AgN5] coordination sphere. The tubes are square with crystallographic dimensions of 10.3 x 10.0 A. The tubes are further linked together through weak interpolymer C-H...F hydrogen bonding interactions into a novel H-bonded three-dimensional network containing square tubes, in which uncoordinated PF(6)(-) counterions and chloroform guest molecules are located. Compound 6 ([Ag(mu-C(6)H(6)N(2)O)](SO(3)CF(3)), monoclinic, P2(1)/c; a = 12.3435(6) A, b = 20.3548(10) A, c = 9.0861(5) A, Z = 8) was obtained by combination of AgSO(3)CF(3) and L6 in a methylene chloride/benzene mixed solvent system. In 6, 2-acetylpyrazine, which was generated from the hydrolysis reaction of L6 in the presence of CF(3)SO(3)(-) and a small quantity of water in solvent, chelates the Ag(I) centers through the carbonyl O-donor, and the vicinal pyrazine N-donor, furthermore, uses the para-N atoms to link other Ag(I) centers into one-dimensional zigzag chains. The triflate anions link the chains into a three-dimensional network by somewhat long Ag.O contacts.

Syntheses and Structures of Ag(I)-Containing Coordination Polymers and Co(II)-Containing Supramolecular Complex Based on Novel Fulvene Ligands

Three new rigid conjugated fulvene ligands L1-L3 were synthesized. L1 and L3 have been prepared by an aroylation reaction of cyclohexyl-substituted cyclopentadienyl anions. L2 was prepared by the reaction of L1 with PhNHNH2 in hot enthanol. Six new coordination polymers, namely [Ag(C25H20N2O2)(ClO4)] x 3.5C6H6 (1), [Ag2(mu-C31H24N4)(eta2-C6H6)(H2O)](ClO4)2 x (C6H6) x (H2O)0.5 (3), [Ag(C31H24N4)]SbF6 x solvate (4), [Ag(C31H24N4)](SbF6)2 x 2C6H6 x CH2Cl2 (5), [Ag(C25H20N2O2)2]SbF6 (6), and [Ag(C25H20N2O2)2]SbF6 (7), and one seven-membered cobaltacycle-containing complex, namely Co(C25H20N2O2)2(C2H5OH)2 (2), were obtained through self-assembly based on these three new fulvene lignads. L2-L3 and compounds 1-7 have been fully characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. The results indicate that the coordination chemistry of new fulvene ligands is versatile. They can bind metal ions not only through the terminal N-donors and fulvene carbon atoms into organometallic coordination polymers but also through the two chelating carbonyl groups into unusual seven-membered metallo-ring supramolecular complexes. In the solid state, ligands L1-L3 are luminescent. A blue-shift in the emission was observed between the free ligand L1 and the one incorporated into Co(II)-containing complex 2, and a red-shift in the emission was observed between the free ligand L3 and the one incorporated into Ag(I)-containing polymeric compounds 6 and 7.

Syntheses, crystal structures, and magnetism of one-dimensional complexes generated from copper(II) and carbamyldicyanomethanide bridging ligand

Two one-dimensional chain complexes, {[Cu(cda)2H2O]·H2O}n (1) and {[Cu(cda)(H2O)2]·(ClO4)·3H2O}n (2) (cda = carbamyldicyanomethanide anion) have been synthesized and their crystal structures determined by X-ray crystallography. The copper(II) ions in 1 are bridged by two µ1,5-cda bridging ligands, whereas in 2 the copper(II) ions are connected by a single µ1,5-cda ligand. Complex 1 is red while 2 is green. Variable-temperature magnetic susceptibility data indicate that there is a very weak antiferromagnetic interaction between the bridged copper(II) ions in both 1 and 2.Key words: synthesis, crystal structure, copper complex, polynitrile ligand, magnetism.

Self-assembly of coordination polymers from AgX (X = SbF(6)(-), PF(6)(-), and CF(3)SO(3)(-)) and oxadiazole-containing ligands

The coordination chemistry of the oxadiazole-containing rigid bidentate ligands 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (L1), 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (L2), and 2,5-bis(3-aminophenyl)-1,3,4-oxadiazole (L3) with inorganic Ag(I) salts has been investigated. Four new coordination polymers (1, 2, 3, and 5) and one new bimetallic macrocyclic supramolecular complex (4) were synthesized from solution reactions of L1-L3 with inorganic Ag(I) salts, respectively. Compounds [[Ag(L1)]SbF(6)](n) (1) (1, monoclinic, P2(1)/c, a = 6.6846(4) A, b = 27.1113(15) A, c = 8.6802(5) A, beta = 94.1080(10) degrees, Z = 4) and [[Ag(L1)]PF(6)](n) (2) (2, monoclinic, P2(1)/c, a = 6.6753(3) A, b = 27.2824(14) A, c = 8.2932(4) A, beta = 94.6030(10) degrees, Z = 4) were obtained from the reactions of L1 with AgSbF(6) and AgPF(6) in a CH(2)Cl(2)/CH(3)OH mixed solvent system, respectively. Compounds 1 and 2 are isostructural and feature a novel two-dimensional zeolite-like net with two different individual rings. [[Ag(L2)]SbF(6)](n) (3) (3, monoclinic, P2(1)/c, a = 5.5677(3) A, b = 17.3378(9) A, c = 15.6640(8) A, beta = 94.4100(10) degrees, Z = 2) and [Ag(2)(L2)(2)](SbF(6))(2) (4) (4, triclinic, P1, a = 8.7221(5) A, b = 9.2008(6) A, c = 10.7686(7) A, alpha = 70.6270(10) degrees, beta = 75.7670(10) degrees, gamma = 73.7560(10) degrees, Z = 1) were obtained from one-pot reaction of L2 with AgSbF(6) in a CH(2)Cl(2)/CH(3)OH mixed solvent system. Compound 3 features a one-dimensional chain pattern, while compound 4 adopts a novel bimetallic macrocyclic structural motif which consists of Ag(2)(L2)(2) ringlike units (crystallographic dimensions, 8.06 x 7.42 A(2)). [[Ag(L3)]SO(3)CF(3)](n) (5) is generated from L3 and AgSO(3)CF(3) in a CH(2)Cl(2)/CH(3)OH mixed solvent system and crystallizes in the unusual space group Pbcn, with a = 9.8861(5) A, b = 20.2580(10) A, c = 17.5517(8) A, Z = 8. It adopts novel two-dimensional sheets that are cross-linked to each other by strong interlayer N-H...O hydrogen bonding interactions into a novel H-bonded three-dimensional network.

Spiral, herringbone, and triple-decker silver(I) complexes of benzopyrene derivatives assembled through eta(2)-coordination

Three novel silver(I) complexes with benzopyrene derivatives were synthesized and characterized in this paper. Treatment of AgClO(4)*H(2)O with 7-methylbenzo[a]pyrene (L(1)) afforded [Ag(2)(L(1))(toluene)(0.5)(ClO(4))(2)](n)() (1) which exhibits a 2-D sheet structure with double-stranded helical motifs. Reaction of AgCF(3)SO(3) with dibenzo[b,def ]chrysene (L(2)) gave rise to an unprecedented cocrystallization structure, ([Ag(2)(L(2))(CF(3)SO(3))(2)][Ag(2)(toluene)(2)(CF(3)SO(3))(2)])(n)() (2), formed by a 2-D neutral lamellar polymer and a 1-D neutral rodlike one. The ligand benzo[e]pyrene (L(3)) coordinated to silver(I) ions generating a closed triple-decker tetranuclear complex [Ag(4)(L(3))(4)(p-xylene)(ClO(4))(4)] (3) which can be regarded as a stacking polymer owing to existing intermolecular pi-pi stack interactions. The structural diversity of the silver(I) coordination polymers with polycyclic aromatic hydrocarbons is not only related to the stacking patterns of free polycyclic aromatic hydrocarbons in the crystalline state, but also the geometric shapes of the molecules for these free ligands. In addition, the coordination of solvents to metal ions plays a crucial role in the formation of the unprecedented coordination polymeric architectures. The ESR spectroscopic results, conductivity, and synthesis properties are also discussed.

Two Versatile N,N‘-Bipyridine-Type Ligands for Preparing Organic−Inorganic Coordination Polymers: New Cobalt- and Nickel-Containing Framework Materials

The Schiff base ligands 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene (L1, monoclinic, P2(1)/c, a = 3.856(1) A, b = 11.032(2) A, c = 12.738(3) A, beta = 92.21(3) degrees, Z = 2) and 2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene (L2, monoclinic, P2(1)/c, a = 10.885(2) A, b = 4.613(1) A, c = 14.978(3) A, beta = 92.827(4) degrees, Z = 2) were used in the synthesis of four new organic-inorganic coordination polymers, each of them adopting a different structural motif. Synthesis, X-ray structural determinations, and spectroscopic and thermogravimetric analyses are presented. The reaction between Co(NO(3))(2).6H(2)O and L1 afforded a two-dimensional noninterpenetrating brick-wall structure, [Co(C(12)N(4)H(10))(1.5)(NO(3))(2)(H(2)O)(CH(2)Cl(2))(2)](n)() (1, triclinic, P1; a = 10.242(7) A, b = 10.802(7) A, c = 15.100(1) A, alpha = 70.031(1), beta = 75.168(11), gamma = 76.155(11), Z = 2), while Ni(NO(3))(2).6H(2)O combined with L1 yielded an interpenetrating three-dimensional rhombus-grid polymer, [Ni(C(12)N(4)H(10))(2)(NO(3))(2)(OC(4)H(8))(1.66)(H(2)O)(0.33)](n) (2, monoclinic, C2/c; a = 20.815(8) A, b = 23.427(8) A, c = 17.291(6) A, beta = 116.148(6), Z = 8). The reaction of Co(NO(3))(2).6H(2)O and L2 was found to be solvent-sensitive and resulted in the formation of two different noninterpenetrating compounds: [Co(C(14)N(4)H(14))(2)(NO(3))(2)(C(6)H(6))(1.5)](n)() (3, monoclinic, C2/c; a = 22.760(2) A, b = 21.010(3) A, c = 25.521(2) A, beta = 97.151(2), Z = 8), which adopts a two-dimensional square-grid motif formed by propeller-type modules, and [Co(C(14)N(4)H(14))(1.5)(NO(3))(2)(CH(2)Cl(2))(2)](n)() (4, monoclinic, P2(1)/n; a = 14.432(2) A, b = 14.543(8) A, c = 15.448(4) A, beta = 96.968(0), Z = 4), consisting of T-shaped building blocks assembled into a one-dimensional ladder-type structure. These four coordination polymers all exhibit impressive thermal stability. Thermogravimetric studies showed that after complete removal of the solvents, the frameworks are stable to temperatures between 234 degrees C and 260 degrees C.

New inorganic/organic coordination polymers generated from bidentate Schiff-base ligands

The coordination chemistry of the long conjugated bidentate Schiff-base ligands 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene (L1) and 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene (L2) with cadmium and cobalt nitrate hydrates is investigated. Four new coordination polymers are prepared by solution reactions and fully characterized by infrared spectroscopy, elemental analysis, thermogravimetric analysis, and single-crystal X-ray diffraction. [Cd(NO3)2(L1)(1.5).0.5(L1)]n (1; monoclinic, P2(1)/c; a = 7.7729(16) A, b = 19.049(4) A, c = 17.865(4) A, beta = 93.13(3) degrees, Z = 4) is obtained by combination of L1 with Cd(NO3)(2).4H2O in a benzene/methanol or THF/methanol mixed-solvent system. The structure features two-dimensional brick wall sheets that are cross-linked by weak noncovalent pi-pi interactions (alternating face-to-face stacking of coordinated and uncoordinated L1 molecules) to generate a novel three-dimensional network. [Co(NO3)2(L1)(1.5).H2O]n (2; orthorhombic, Ccca; a = 19.031(4) A, b = 33.627(7) A, c = 14.299(3) A, Z = 4) is generated from the reaction of L1 with Co(NO3)(2).6H2O in a benzene/ethanol mixed-solvent system. It forms with a unique three-dimensional framework that can be considered a new polymeric motif based on the 1:1.5 metal-to-ligand composition M(L)1.5. The Cd(II) and Co(II) centers in 1 and 2, which lie in seven-coordinate environments, generate two new types of building blocks. The topologies of these two new building blocks are distinctly different from the common "T-shaped" building block generated from the same (MN3O4) coordination environment reported previously. Cd(L2)2(NO3)2 (3) and Co(L2)2(NO3)2 (4) are obtained by combination of L2 with Cd(NO3)(2).4H2O and Co(NO3)(2).6H2O, respectively. Compounds 3 and 4 are isostructural, crystallizing in the monoclinic space group P2(1)/n, with a = 8.5802(17) A, b = 17.506(4) A, c = 10.443(2) A, beta = 96.59(3) degrees, and Z = 2 for 3 and a = 8.5283(17) A, b = 17.408(4) A, c = 10.229(2) A, beta = 97.05(3) degrees, and Z = 2 for 4. 3 and 4 adopt a novel one-dimensional chain structural motif, consisting of M2(L2)2 (M = Cd, Co) ringlike units. O...H-C hydrogen-bonding interactions in both 3 and 4 play a significant role in aligning the polymer strands in the solid state.

2-D interwoven and 3-D 5-fold interpenetrating silver(I) complexes of 1-(isocyanidomethyl)-1H-benzotriazole and 1,3-bis(dicyanomethylidene)indan

This paper presents novel and distinctive organosilver polymers with intriguing structure motifs, constructed from iodoacetonitrile (L1), 1-(isocyanidomethyl)-1H-benzotriazole (L2), 1,3-bis(dicyanomethylidene)indan (L3), and silver(I) salts, respectively. Treatment of L1 with AgClO4 generated [Ag(L1)(ClO4)]n (1), whose X-ray determination revealed a 2-D wavy sheet structure with square grids. Reaction of L2 with AgPF6 gave rise to a novel 2-D wavy interwoven network, ([Ag(L2)(PO2F2)0.5])n (2). The complex [Ag2(L3)2]n (3) obtained by reaction of AgClO4 with L3 can be regarded as unprecedented 3-D 5-fold interpenetrating nets with columnar aromatic stacks and indicates semiconductive behavior. The IR, ESR spectroscopic results, conductivities, and structural features of the complexes are discussed, respectively. The present findings may provide insight into the coordination versatility of silver(I) and polynitrile ligands and an inspiration for the self-assembly of novel supramolecular networks with multifunctional ligands. Crystal data: 1, C2H2AgINClO4, orthorhombic, Pca2(1) (No. 29), a = 14.503(1) A, b = 5.104(2) A, c = 10.2019(9) A, Z = 4; 2, C8H6AgN4PF4O, orthorhombic, Pnna (No. 52), a = 12.2705(3) A, b = 21.150(1) A, c = 10.040(1) A, Z = 8; 3, C30H10Ag2N8, triclinic, P1 (No. 2), a = 14.920(2) A, b = 11.896(2) A, c = 7.400(4) A, alpha = 86.55(2) degrees, beta = 80.87(2) degrees, gamma = 74.47(1) degrees, Z = 2.

Reactions of Cu(hfacac)(2).H(2)O (hfacac = Hexafluoroacetylacetonate) with Bidentate Ligands. Preparation, Characterization, and X-ray Structures of the Molecular Complexes Cu(hfacac)(2)(pyrazine)(2) and Cu(hfacac)(2)(3-cyanopyridine)(2) and the One-Dimensional Coordination Polymers Cu(hfacac)(2)(1,2-bis(4-pyridyl)ethane) and Cu(hfacac)(2)(4,4'-trimethylenebipyridine)

Reactions of Cu(hfacac)(2).H(2)O (hfacac = hexafluoroacetylacetonate) with pyrazine, 3-cyanopyridine, 1,2-bis(4-pyridyl)ethane, and 4,4'-trimethylenebipyridine in methylene chloride have been studied. Two types of products were obtained and crystallographically characterized: compounds 1 (Cu(hfacac)(2)(pyrazine)(2), orthorhombic, Pbca; a = 9.839(2) Å, b = 17.984(2) Å, c = 13.572(2) Å, Z = 4) and 2 (Cu(hfacac)(2)(3-cyanopyridine)(2), triclinic, P&onemacr;, a = 13.175(2) Å, b = 13.955(2) Å, c = 7.936(2) Å, alpha = 104.29(2) degrees, beta = 105.90 degrees, gamma = 81.47(1) degrees, Z = 2) were isolated as molecular complexes, while compounds 3 (Cu(hfacac)(2)(1,2-bis(4-pyridyl)ethane, monoclinic, P2(1)/c, a = 7.922(1) Å, b = 16.266(4) Å, c = 10.163(2) Å, beta =93.83(1) degrees, Z = 2) and 4 (Cu(hfacac)(2)(4,4'-trimethylenebipyridine), monoclinic, Pc, a = 7.940(1) Å, b = 9.691(2) Å, c = 18.539(3) Å, beta = 95.83(2) degrees, Z = 2) were isolated as one-dimensional infinite polymeric chains. The structures were further characterized by infrared spectroscopy, thermogravimetry, and elemental analysis; additionally, the magnetic behavior of all compounds was investigated and found to follow the Curie law. All four compounds feature similar 4 + 2 pseudooctahedral coordination environments around the Cu(II) centers composed of square-planar Cu(hfacac)(2) units with the N-donor ligands occupying the trans positions. The length of the N-donor ligands determines the formation of either molecular complexes (1 and 2, short ligands) or infinite polymeric structures (3 and 4, longer ligands). Important C-F.H-C hydrogen-bonding interactions in compounds 1 and 3 play a significant role in aligning the molecules and the polymer strands in the crystalline solids.