Investigations on the synthesis, structures, and properties of new copper(I) 2,3-dimethylpyrazine coordination compounds

Five new coordination compounds were prepared, structurally characterized, and investigated for their thermal properties. In the structure of the ligand-rich 4:9 compound, tetra(mu2-chloro)bis(mu2-2,3-dimethylpyrazine-N,N')tetrakis(2,3-dimethylpyrazine-N)tetracopper(I) tris(2,3-dimethylpyrazine)solvate (I), discrete complexes are formed by build up of two [(CuCl-(2,3-dimethylpyrazine)2]2 dimers, which are connected by two 2,3-dimethylpyrazine ligands via mu-N,N' coordination. In the 1:1 compound poly[mu2-chloro-mu2-2,3-dimethylpyrazine-N,N'-copper(I)] (II), (CuCl)2 dimers are found, which are connected by the 2,3-dimethylpyrazine ligands into layers. For this composition, a second polymorphic modification was found (III), which exhibits a different topology of the coordination network and a different packing of the layers. In the most stable 3:2 compound catena[tri(mu2-chloro)bis(mu2-2,3-dimethylpyrazine-N,N')tricopper(I)] (IV), six-membered rings of (CuCl)3 are found, which are connected by the 2,3-dimethylpyrazine ligands into chains. In the ligand-deficient 2:1 compound, poly[di(mu3-chloro)(mu2-2,3-dimethylpyrazine-N,N')dicopper(I)] (V), CuCl double chains are found, which are connected by the 2,3-dimethylpyrazine ligands into layers. On heating, compound I transforms quantitatively into the 3:2 compound IV without the formation of II or III as intermediates. Compound IV is also obtained by heating either the 1:1 compound II or III. On further heating, the 3:2 compound IV loses additional ligands, forming the ligand-deficient 2:1 compound V, which then decomposes into CuCl. The stability, thermal reactivity, and the transition behavior of all compounds were investigated using different thermoanalytical methods. These results are compared with those previously reported for the structurally similar CuCl(2-ethylpyrazine) coordination compounds. The formation and the stability of the different compounds in solution were also investigated.     

Synthesis,crystal structures,and thermal and thermodynamic properties of dimorphic copper(I) coordination polymers

A second modification of the literature-known copper(I) coordination polymer CuCl(pyridazine) was prepared by the reaction of CuCl with pyridazine in acetonitrile. The crystal structure of catena[CuCl(mu(2)-pyridazine-N,N)] is built up of CuCl chains of which each two are connected by the pyridazine ligands to form double chains that are directed parallel to the crystallographic a-axis. In the literature known form LI (CuCl)(2) dimers occur that are connected to chains by the pyridazine ligand. On heating, compound I and LI lose half of the pyridazine ligands and transform to the new 2:1 coordination polymer poly[(CuCl)(2)(pyridazine-N,N)] (II), which transforms at higher temperatures to CuCl. The crystal structure of II is composed of discrete CuCl tetra-chains that are linked by the pyridazine ligands to sheets parallel to (010). The same thermal reactivity is found for the literature-known compound CuBr(pyridazine) (LII), which is isotypic to LI. On heating LII a transformation into the new 2:1 compound poly[(CuBr)(2)(pyridazine-N,N)] (III) is observed, which is isotypic to II. The thermal reactivity of all compounds and the transformation behavior as well as the range of thermodynamic stability of the dimorphic modifications were studied using DTA-TG-MS and DSC measurements, temperature dependent X-ray powder investigations, and crystallization experiments.     

On the thermal decomposition pathway of coordination compounds: synthesis,crystal structures and properties of new polymorphic CuI(2-ethylpyrazine) coordination compounds

Five new coordination compounds were prepared at room temperature in solution, under solvothermal conditions at elevated temperatures or by thermal decomposition reactions. In the amine rich 1:2 compound [(CuI)₂(2-ethylpyrazine-N)₄] (I) discrete molecular complexes are found that consist of (CuI)₂ dimers in which each copper atom is coordinated by two 2-ethylpyrazine ligands. The crystal structure of the 1:1 compound poly[(CuI)₂(μ₂-2-ethylpyrazine-N,N′)₂] (II) contains (CuI)₂ dimers which are connected by the 2-ethylpyrazine ligands into layers parallel to (010). The second modification of a 1:1 compound poly[(CuI)₂(μ₂-2-ethylpyrazine-N,N′)-(2-ethylpyrazine-N)] (III) consists of 8-membered CuI rings, which are connected by the 2-ethylpyrazine ligands into layers. In one modification of poly[(CuI)₂(μ₂-2-ethylpyrazine-N,N′)] (IV) CuI double chains are connected by the ligands into layers parallel to (001). If the preparation is kinetically controlled, crystals of the second modification poly[(CuI)₂(μ₂-2-ethylpyrazine)-N,N′]] (V) can be obtained. The crystal structure of V is very similar to that of compound IV, with the main difference that the orientation of the ethyl groups of the 2-ethylpyrazine ligands is different. The thermal reactivity of all compounds as well as the thermodynamic stability and the transformation behaviour of the polymorphic modifications were investigated using DTA-TG-MS and DSC measurements, temperature resolved X-ray powder diffraction as well as temperature dependent crystallisation experiments. The occurrence of the different phases is discussed and the results are compared with those obtained on the corresponding CuCl and CuBr compounds on the basis of preparative results and density-functional calculations.     

Metal complexes from 1,1'-di(pyrazinyl)ferrocene: coordination polymers and bridged diferrocenes

Ferrocene-based ligands 1,1'-di(pyrazinyl)ferrocene (L1) and 1,1'-di(2-pyrimidinyl)ferrocene (L2) were synthesized and copper and silver complexes were obtained from L1. Coordination polymers [{Cu(2)(PhCOO)(4)}(L1)](n) (1), [{Cu(2)(C(5)H(11)COO)(4)}(L1)](n) (2), and [{Cu(2)(OAc)(4)}(L1)](n).0.5n[Cu(2)(OAc)(4)(H(2)O)(2)].1.5nCH(3)CN (3) resulted from the reaction with the corresponding copper carboxylates. In all three complexes, L1 links the dinuclear copper carboxylate units to form one-dimensional step-like chains. In 2, these chains are further linked by [Cu(2)(OAc)(4)(H(2)O)(2)] dinuclear units via hydrogen bonding to form sheet structures. The reaction of L1 with copper(I) iodide resulted in a multinuclear complex [(CuI)(4)(L1)(2)].(L1) (4), which contains a [(CuI)(4)(L1)(2)] diferrocene unit with a step-like (CuI)(4) core. Reactions of L1 with silver(I) salts resulted in silver-bridged diferrocenes [Ag(2)(L1)(2)]X(2) (X = ClO(4) (5a, b), NO(3) (6a-c) and PF(6) (7)), some of which incorporate aromatic solvents into their crystal lattices. The intramolecular Ag...Ag separations in these metallamacrocycles (3.211-3.430 A) depended upon the counter-anions and on the coordination mode of the silver ions. In all of these coordination complexes, L1adopts a synperiplanar eclipsed conformation and acts as a bidentate ligand, with only the 5-nitrogen of each pyrazine ring involved in coordination.     

The unexpected versatility of P(4)S(3) as a building block in polymeric copper halide networks: 2,3-P, 1,2,3-P and all-P coordination

Layering solutions of P(4)S(3) in CH(2)Cl(2) with solutions of CuCl or CuI in CH(3)CN gives the coordination polymers (P(4)S(3))(3)(CuCl)(7) (1), (P(4)S(3))(2)(CuCl)(3) (2), (P(4)S(3))(CuI) (3) and (P(4)S(3))(CuI)(3) (4), respectively, after slow diffusion. The yellow compounds were characterised by elemental analysis, (31)P magic-angle spinning (MAS) NMR spectroscopy and single-crystal X-ray crystallography. The solid-state structures demonstrate the unexpected ligand versatility of the P(4)S(3) molecule, which interacts through two, three, or even all of the phosphorus atoms with copper according to the nature of the copper halide. Compound 1 has a three-dimensional network in which linear and cylindrical infinite CuCl subunits coexist with diatomic CuCl building blocks. For the first time, all four P atoms of the P(4)S(3) cage are involved in coordination with metal atoms. The 3D structure of 2 contains stacks of P(4)S(3) that are interconnected by slightly undulated and planar [CuCl](n) ribbons. Compound 3 is a one-dimensional polymer composed of alternating (CuI)(2) rings and P(4)S(3) bridges. The structure of 4 consists of undulated [CuI](n) layers in which the P(4)S(3) cage functions as a bridge within the layer, as well as a spacer between the layers. The (31)P MAS NMR spectra obtained are in good agreement with the solid-state structures obtained crystallographically. Thus, analytically pure 3 and 4 show singlet peaks that correspond to uncoordinated P and quartets owing to coupling with (63)Cu and (65)Cu, respectively, whereas that of 1 contains quartets according to all-P coordination. The spectrum of 2 was obtained from a sample that still contained 40 % of 1.     

Entanglement of individual coordination polymers having helicates as building intermediates

A series of Ag(I) coordination compounds, from one-dimensional chains to 3D porous frameworks, were achieved from N,N'-bis[1-(2-pyrazinyl)ethylidene]benzil dihydrazone, L, via self-assembly, using helicates as effective secondary building units. Compound 2 [(Ag(2.75)L)(NO(3))(2.75)] was comprised of two opposite-handed 3D frameworks formed by connecting the 4(1) helical chains into (10(3)-b) nets. The pairs of the racemic 3D frameworks were connected through additional silver(I) centers and entangled each other forming a racemic 3D net. Compound 3 [(Ag(13)L(8))(BF(4))(13)(H(2)O)(12)] was comprised of a 3D framework that was constructed from double-helical building intermediates Ag(2)L(2) with one-dimensional infinite chains being threaded into the large voids of a 3D framework to form a weave structure. The ladder-like chains in compound 4 [(Ag(3)L(2))(ClO(3))(3)(CH(3)OH)(2)(CH(3)CN)] were formed by the addition of excess NaClO(3) into the methanol solution containing AgNO(3) and the ligand L, and the zigzag chains in compound 5 [(Ag(2)L(2))(ClO(4))(2)(CH(3)CN)(2)] were constructed by the addition of excess NaClO(4) into an acetonitrile solution containing AgNO(3) and the ligand L.     

New in situ cleavage of both S-S and S-C(sp2) bonds and rearrangement reactions toward the construction of copper(I) cluster-based coordination networks

Solvothermal reaction of 4,4'-dithiodipyridine (dtdp) with CuI at 120 or 160 degrees C results in the formation of three new coordination networks formulated with [Cu4I4(tdp)2] (1; tdp = 4,4'-thiodipyridine), [Cu5I5(ptp)2] (2), and [Cu6I6(ptp)2] [3; ptp = 1-(4-pyridyl)-4-thiopyridine]. The starting dtdp reagent was unprecedentedly converted into two tdp and ptp ligands via new in situ cleavage of both S-S and S-C(sp2) bonds and temperature-dependent in situ ligand rearrangement of dtdp. 1 is a two-dimensional (2D) Cu4I4 cubane-like coordination network of 2-fold interpenetration. While in 2, the Cu8I8 and Cu2I2 cluster units are alternately connected by the mu2-sulfur bridges into one-dimensional inorganic chains along the a axis, which are further joined by the ptp spacers into a three-dimensional (3D) coordination network of 2-fold interpenetration. 3 is a 3D non-interpenetrating coordination network constructed with 2D inorganic (Cu2I2)n layers and the ptp spacers. 1 displays an intense orange-red emission light with a maximum at ca. 563 nm. While luminescence quenching occurs in 2 and 3 by electron transfer of a photoelectron to the electronegative acceptor molecule of ptp.     

New magnetic copper(II) coordination polymers with the polynitrile ligand (C[C(CN)2]3)2- and N-donor co-ligands

Reactions between CuCl2 and K2tcpd (tcpd2- = [C10N6]2- = (C[C(CN)2]3)2-) in the presence of neutral co-ligands (bpym = 2,2'-bipyrimidine, and tn = 1,3-diaminopropane) in aqueous solution yield the new compounds [Cu2(bpym)(tcpd)2(H2O)4] x 2H2O (1), [Cu(tn)(tcpd)] (2), and [Cu(tn)2(tcpd)] x H2O (3), which are characterized by X-ray crystallography and magnetic measurements. Compound 1 displays a one-dimensional structure in which the bpym ligand, acting with a bis-chelating coordination mode, leads to [Cu2(bpym)]4+ dinuclear units which are connected by two mu2-tcpd2- bridging ligands. Compound 2 consists of a three-dimensional structure generated by [Cu(tn)]2+ units connected by a mu4-tcpd2- ligand. The structure of 3 is made up of centrosymmetric planar [Cu(tn)]2+ units connected by a mu2-tcpd2- ligand leading to infinite zigzag chains. In compounds 1 and 3, the bridging coordination mode of the tcpd2- unit involves only two nitrogen atoms of one C(CN)2 wing, while in 2, this ligand acts via four nitrogen atoms of two C(CN)2 wings. Despite this difference, the structural features of the tcpd2- units in 1-3 are essentially similar. Magnetic measurements for compound 1 exhibit a maximum in the chi(m) vs T plot (at approximately 150 K) which is characteristic of strong antiferromagnetic exchange interactions between the Cu(II) metal ions dominated by the magnetic exchange through the bis-chelating bpym. The fit of the magnetic data to a dimer model gives J and g values of -90.0 cm(-1) and 2.12, respectively. For compounds 2 and 3 the thermal variations of the magnetic susceptibility show weak antiferromagnetic interactions between the Cu(II) metal ions that can be well reproduced with an antiferromagnetic regular S = 1/2 chain model that gives J values of -0.07(2) and -0.18(1) cm(-1) with g values of 2.12(1) and 2.13(1) for compounds 2 and 3, respectively (the Hamiltonian is written in all the cases as H = -2JS(a)S(b)).     

Copper(I) Coordination Polymers with Alkanedithiol and ‐dinitrile Bridging Ligands

CuI‐based coordination polymers with 1, 2‐ethanedithiol, 3, 6‐dioxa‐1, 8‐octanedithiol and 3‐oxa‐1, 5‐pentanedinitrile as respectively μ‐S, S′ and μ‐N, N′ bridging ligands have been prepared by reaction of CuI with the appropriate alkane derivative in acetonitrile. equation/tex2gif-stack-1.gif[Cu(HSCH₂CH₂SH)₂]I ( 1 ) contains 4⁴ cationic nets, equation/tex2gif-stack-2.gif[(CuI)₂(HSCH₂CH₂OCH₂CH₂OCH₂CH₂SH)] ( 2 ) neutral layers in which stairlike CuI double chains are linked by dithiol spacers. In contrast to these 2D polymers, equation/tex2gif-stack-3.gif[CuI(NCCH₂CH₂OCH₂CH₂CN)] ( 3 ) and equation/tex2gif-stack-4.gif[(CuI)₄(NCCH₂CH₂OCH₂CH₂CN)₂] ( 4 ) both contain infinite chains with respectively (CuI)₂ rings and distorted (CuI)₄ cubes as building units. Solvothermal reaction of CuI with the thiacrown ether 1, 4, 10‐trithia‐15‐crown‐5 (1, 4, 10TT15C5) in acetonitrile affords the lamellar coordination polymer equation/tex2gif-stack-5.gif[(CuI)₃(1, 4, 10TT15C5)] ( 7 ) in which copper atoms of individual CuI double chains are bridged in a μ‐S1, S4 manner. The third sulphur atom S10 of the thiacrown ether coordinates a copper(I) atom from a parallel chain to generate a 2D network.     

Three New Iron(II) Thiocyanato Coordination Polymers Based on 4,4′‐Bipyridine as Ligand and the Influence of Methanol on Their Structures

Reaction of iron(II) thiocyanate with 4,4‐bipyridine (bipy) in methanol leads to the formation of three new solvates of different composition depending on the reaction conditions: At room temperature two new ligand‐rich 1:2 (1:2 = ratio between metal and N‐donor ligand) polymorphic forms [Fe(NCS)₂(bipy)₂ · 2MeOH]_n ( 1I ) and [Fe(NCS)₂(bipy)(MeOH)₂ · (bipy)]_n ( 1II ) are obtained, whereas solvothermal conditions leads to the formation of the new ligand‐deficient 1:1 compound [{Fe(NCS)₂(bipy)(MeOH)}₂]_n ( 2 ). All crystal structures were determined by X‐ray single crystal structure analysis. In the crystal structure of modification 1I the metal atoms are coordinated by four bridging bipy ligands, which connect them into layers. The methanol molecules occupy voids in the structure. Compared to 1I in modification 1II the crystal structure contains of linear Fe–bipy–Fe chains, which are further connected by hydrogen bonds between coordinating MeOH and noncoordinated bipy ligands into layers. The ligand‐deficient 1:1 compound 2 shows a completely different coordination topology with linear Fe–bipy–Fe chains, which are connected by coordinating methanol molecules into double‐chains. In all compounds the thiocyanato anions are terminal N‐bonded to the metal atoms. Investigation of the thermal behavior of compound 1I shows a two‐step decomposition, in which ligand‐deficient intermediates are formed. Magnetic measurements on 1I reveal Curie–Weiss paramagnetism with increasing antiferromagnetic interactions on cooling.     

Dimorphism of a new CuI coordination polymer:synthesis,crystal structures and properties of catena[CuI(2-iodopyrazine-N)] and poly[CuI(mu2-2-iodopyrazine-N,N')

Two modifications of the new copper(I) iodide coordination polymer CuI(2-iodopyrazine) were obtained by the reaction of CuI and 2-iodopyrazine in acetonitrile. During this reaction, intensely yellow crystals of form I appear first which transform within several minutes to intensely red crystals of form II which is the thermodynamically most stable form at room temperature. In catena[CuI(2-iodopyrazine-N)] (form I; a = 4.1830 (6) A; b = 10.814 (1) A; c = 17.961 (4) A; V = 812.5 (2) A(3); orthorhombic; P2(1)2(1)2(1); Z = 4), corrugated CuI double chains are found in which each copper atom is coordinated by one additional 2-iodopyrazine ligand. In poly[CuI(mu-2-iodopyrazine-N,N')] (form II; a = 4.2679 (5) A; b = 13.942 (2) A; c = 13.017 (2) A; b = 92.64 (1) degrees; V = 773.76 (2) A(3); monoclinic; P2(1)/c; Z = 4), CuI single chains occur which are connected via mu-N,N' coordination by the 2-iodopyrazine ligands to layers parallel to (010). The thermal behavior of both forms was investigated using simultaneous differential thermoanalysis, thermogravimetry, and mass spectrometry as well as differential scanning calorimetry and temperature resolved X-ray powder diffraction. On heating, both forms decompose to copper(I) iodide, and the decomposition temperature of form I is significantly lower than that of form II. From all experiments, there is no indication of a phase transition of one form into the other or for the formation of a phase with lower amine content.     

Synthesis, a case of isostructural packing, and antimicrobial activity of silver(I)quinoxaline nitrate, silver(I)(2,5-dimethylpyrazine) nitrate and two related silver aminopyridine compounds

The synthesis and low temperature crystal structures of [Ag(quinoxaline)]n(NO3)n, 1, [Ag(2,5-dimethylpyrazine)(NO3)]n, 2 and [Ag4(3-aminopyridine)4(NO3)4]n 3 are presented. The quinoxaline compound forms a 1D coordination polymer with the characteristic linear 2-coordination figure of silver(I), the N-Ag-N angle being 164.2(1) degrees, and only weak silver-nitrate interactions. In addition there is an interaction giving pairs of parallel chains as the main structural theme. The 2,5-dimethylpyrazine compound has approximately trigonal-planar coordination, also binding one nitrate at the relatively short Ag-O distances 2.444(3) angstroms and 2.484(3) angstroms, respectively, for the two crystallographically different silver atoms. This also results in a 1D coordination polymer that, despite the large differences in the Ag(I) coordination environment, is isostructural with 1. [Ag4(3-aminopyridine)4(NO3)4]n 3 forms a 2D coordination polymer by bridging nitrate ions. The antimicrobial activity of 1-3, and also of [Ag3(2-aminopyridine)4](NO3)3, 4 was screened for 13 different pathogens and substantial activity was shown for 1 against Escherichia coli and Pseudomonas aeruginosa (MIC 4 microg cm(-3)) and somewhat lower activity was registered against Sarcina lutea and Salmonella typhi for 1, Bordetella bronchiseptica for 2, Salmonella typhi and Pseudomonas aeruginosa for 3, and Escherichia coli and Shigella sonnie for 3 (MIC 8 microg cm(-3)). Only low activity was shown against the yeast Candida albicans for 1, 2 and 4 whereas no activity against this pathogen was registered for 3.     

Control of copper(I) iodide architectures by ligand design: angular versus linear bridging ligands

A family of coordination polymers formed by the reaction of copper(I) iodide with a range of angular bidentate or tridentate N-donor ligands is reported. The framework polymers [CuI(dpt)](infinity) 1 [dpt = 2,4-bis(4-pyridyl)-1,3,5-triazine], [CuI(dpb)](infinity) 2 [dpb = 1,4-bis-(4-pyridyl)-benzene], [(CuI)3(dpypy)2](infinity) 3, [CuI(dpypy)](infinity) 4 [dpypy = 3,5-bis(4-pyridyl)-pyridine], and [Cu3I3(pypm)](infinity) 5 [pypm = 5-(4-pyridyl)pyrimidine] have been prepared and structurally characterized. It was found that the angular nature of the dpypy and dpt ligands favors the formation of discrete (CuI)2 dimeric subunits as observed in [CuI(dpt).MeCN](infinity) 1 and [(CuI)3(dpypy)2](infinity) 3. In contrast, reaction with the linear ligand dpb affords [CuI(dpb)](infinity) 2 which incorporates a one-dimensional (CuI)(infinity) chain structure. Moreover, the additional donor available on the central ring of the dpypy ligand generates a novel two-dimensional bilayer structure in 3, in contrast to the one-dimensional ribbon structure observed in the case of 1. Interestingly, the bilayer structure of 3 additionally exhibits 2-fold interpenetration. The reaction of CuI with dpypy produces not only 3 but a further product [CuI(dpypy)](infinity) 4 that has been characterized as a one-dimensional chain constructed from trigonal-planar Cu(I) centers bridged by bidentate dpypy ligands. Compound 5, [Cu3I3(pypm)](infinity), exhibits a highly unusual three-dimensional structure in which the pypm ligand bridges two-dimensional brick-wall (CuI)(infinity) sheets.     

Zur Reaktion der Alkin-Kupfer(I)-Komplexe [CuX(S-Alkin)] (X = Cl,Br, I; S-Alkin = 3,3,6,6-Tetramethyl-1-thia-4-cycloheptin) mit dem Chelat-Liganden N,N,N′,N′-Tetramethylethylendiamin (tmeda)

Organometallic Compounds of Copper. XVII. On the Reaction of the Alkyne-Copper(I) Complexes [CuX(S-Alkyne)] (X = Cl, Br, I; S-Alkyne = 3,3,6,6-Tetramethyl-1-thiacyclohept-4-yne) with the Chelate Ligand N,N,N′,N′-Tetramethylethylendiamine (tmeda) The alkyne copper(I) chloride complex [CuCl(S-Alkyne)]_n ( 2 a ) (S-Alkyne = 3,3,6,6–tetramethyl-1-thiacyclohept-4-yne) adds tetramethylethylene diamine (tmeda) to form the mononuclear compound [CuCl(S-Alkyne)(tmeda)] ( 4 ). The alkyne copper halide complexes [CuBr(S-Alkyne)]_n ( 2 b ) and [CuI(S-Alkyne)]_n ( 2 c ) react with tmeda to yield the complex salts [Cu(S-Alkyne)(tmeda)]⁺ [CuX₂(S-Alkyne)]^– (X = Br ( 5 a ), X = I ( 5 b )). X-ray diffraction studies on all new compounds 4 and 5 reveal distorted tetrahedral coordination of the copper atom in complex 4 and trigonal-planar coordinated copper atoms in the cations and anions of the ionic compounds 5 .     

Synthesis and reactivity of copper(I) complexes containing a bis(imidazolin-2-imine) pincer ligand

The new pincer ligand 2,6-bis[(1,3-di-tert-butylimidazolin-2-imino)methyl]pyridine (TL(tBu)) has been prepared in high yield from 2,6-bis(hydroxymethyl)pyridine (1) and 1,3-di-tert-butylimidazolin-2-imine (3). Reaction of TL(tBu) with [Cu(MeCN)4]PF6 affords the highly reactive copper(I) complex [(TL(tBu))Cu]PF6, [5]PF6, which forms the stable copper(I) isocyanide complexes [6a]PF6 (nu(CN) = 2179 cm(-1)) and [6b]PF6 (nu(CN) = 2140 cm(-1)) upon addition of tert-butyl or 2,6-dimethylphenyl isocyanide, respectively. For the cations 6a and 6b, DFT calculations reveal ground-state electronic structures of the type [(TL(tBu)-kappaN(1):kappaN(2))Cu(CNR)] with tricoordinate geometries around the copper atoms. Exposure of [5]PF6 to the air readily leads to trapping of atmospheric CO2 to form the square-planar complex [(TL(tBu))Cu(HCO3-kappaO)]PF6, [7]PF6, with the bicarbonate ligand adopting a rarely observed monodentate coordination mode. In chlorinated solvents such as dichloromethane or chloroform, [5]PF(6) rapidly abstracts chloride by reductive dechlorination of the solvent to yield [(TL(tBu))CuCl]PF6, [8]PF6 quantitatively. Reaction of TL(tBu) with copper(I) bromide or chloride affords complexes 9a and 9b, respectively, for which X-ray diffraction analysis, low-temperature NMR experiments and DFT calculations reveal the presence of a kappa(2)-coordinated ligand of the type [(TL(tBu)-kappaN(1):kappaN(2))CuX]. In solution, complex 9b undergoes slow disproportionation forming the mixed-valence copper(II)/copper(I) system [(TL(tBu))CuCl][CuCl2], [8]CuCl2 with a linear dichlorocuprate(I) counterion.     

Exo-metal coordination by a tricyclic [(P(mu-N-2-NC5H4))2(mu-O)]2 dimer in [(P(mu-N-2-NC5H4))2(mu-O)]2(CuCl x (C5H5N)2)4 (2-NC5H4 = 2-pyridyl, C5H5N = pyridine)

The in situ reaction of the phosphazane dimer [CIP(mu-N-2-NC5H4)]2 (2) with CuCl in the presence of CsH5N/H2O gives the title complex [(P(mu-N-2-NC5H4))2(mu-O)]2(CuCl x (C5H5N)2)4 (1), containing a tricyclic [(P(mu-N-2-NC5H4))2(mu-O)]2 ligand which is isoelectronic with species of the type [(P(mu-NR))2NR]2.     

Investigation into the formation of supramolecular compounds from mixed As/S-ligand complexes [(Cp*Mo)2As2S3] (Cp* = C5Me5) and copper halides

The coordination behavior of [(Cp*Mo)2As2S3] (3) (Cp* = C5Me5) toward Cu(I) halides was investigated. One dimensional polymers of the general formula [(Cp*Mo)2As2S3(CuHal)2]n (Hal = Cl, 4; Br, 5) and an oligomer of composition [{(Cp*Mo)2As2S3}3(CuI)7] (6) formed upon the reaction of 3 with the corresponding copper halide. All of the compounds were characterized by ESI-MS, elemental analysis, and single-crystal X-ray crystallography. The solid-state structures of 4 and 5 are isostructural and contain 1D S-shaped chains. This peculiar folding is achieved by alternating planar and folded Cu2Hal2 rings linked together by the central monosulfide bridge of the middle deck of the organometallic unit. The structure of 6 is characterized by a novel [CuI]7 aggregate, which forms a very flat Cu6I3S3 bowl along with three integrated peripheral [(Cp*Mo)2As2S3] building blocks. In contrast to earlier findings, the middle deck of the organometallic units consists in all structures of two trapezoidal AsS dumbbells and one monosulfide ligand.     

Influence of steric hindrance of organic ligand on the structure of Keggin-based coordination polymer

Five Keggin-based 3D coordination polymers, namely, [Cu3(pz)3(PW12O40)] (pz = pyrazine) (1), [Cu3(2,3-Me2pz)3(PW12O40)] (2,3-Me2pz = 2,3-dimethylpyrazine) (2), [Cu2(2,5-Me2pz)(1.5)(2,5-HMe2pz)(PW12O40)] (2,5-Me2pz = 2,5-dimethylpyrazine) (3), [Cu3(2,3-Me2pz)3(PMo12O40)] (4), and [Ag3(pz)3(PW12O40)].0.5H2O (5), were synthesized and structurally characterized. Crystal data are as follows: trigonal, space group R3c, a = 18.4070(14) angstroms, c = 22.544(3) angstroms, gamma = 120 degrees, and Z = 6 for 1; orthorhombic, space group Pccn, a = 16.599(2) angstroms, b = 20.470(3) angstroms, c = 14.3757(18) angstroms, and Z = 4 for 2; triclinic, space group P1, a = 10.667(2) angstroms, b = 11.147(2) angstroms, c = 20.207(4) angstroms, alpha = 90.983(4) degrees, beta = 108.128(3) degrees, gamma = 92.150(4) degrees, and Z = 2 for 3; orthorhombic, space group Pccn, a = 16.450(3) angstroms, b = 20.170(4) angstroms, c = 14.244(3) angstroms, and Z = 4 for 4; and rhombohedral, space group R32, a = 18.2047(13) angstroms, c = 23.637(3) angstroms, gamma = 120 degrees, and Z = 6 for 5. Their structural differences were investigated using crystal structure analysis, revealing that the influence of steric hindrance of organic ligand on the structures of Keggin-based coordination polymers is realized through changing the number of metal-organic units surrounding the POM anion.     

Synthesis, crystal structures and thermal properties of new copper(I)halide 2-ethylpyrazine coordination polymers: the influence of solid-state kinetics on product formation

Three new copper(I) coordination polymers were prepared by the reaction of copper(I) chloride with 2-ethylpyrazine in water at room temperature or under solvothermal conditions. In poly[CuCl(μ₂-2-ethylpyrazine-N,N′)] (I), “zig-zag”-like CuCl chains are present, which are connected by the 2-ethylpyrazine ligand to a three-dimensional network. In comparison in catena[Cu₃Cl₃(μ₂-2-ethylpyrazine-N,N′)₂] (II) six-membered Cu₃Cl₃ rings occur, which are connected to chains by the organic ligands. In poly[Cu₂Cl₂(μ₂-2-ethylpyrazine-N,N′)] (III), CuCl double chains are found, which are linked by the ligands to form sheets. The thermal behaviour of the different compounds was investigated using simultaneous thermogravimetry, differential thermoanalysis and mass spectroscopy as well as temperature-dependent X-ray powder diffraction. Two mass steps are found upon heating compound I in a thermobalance with 1°C/min, where the first corresponds to the transformation into compound III, and the second to the loss of the remaining ligands under formation of CuCl. If the heating rate is increased to 16°C/min, compound II is formed as an intermediate in a consecutive reaction. Therefore, the product formation depends on the actual heating rate, which shows that the solid-state kinetics plays an important role in such thermal reactions.     

Synthesis,Crystal Structures,and Properties of the Copper(I) Halide Coordination Polymers 2[CuX(μ‐2‐chloropyrazine‐N,N')] (X = Cl,Br), 1[CuI(2‐chloropyrazine‐N)], and [Cu2I2(2‐chloropyrazine)]

The new copper coordination polymers 2[CuX(μ‐2‐chlor‐opyrazine‐N, N')] (X = Cl ( I ), Br ( II ), 1[CuI(2‐chloropyrazine‐N)] ( III ) and [Cu₂I₂(2‐chloropyrazine)] ( IV ) has been prepared by the reaction of the copper(I) halides with 2‐chloropyrazine at roomtemperature or under hydrothermal conditions. The crystal structures of the 1:1 compounds I and II consist of zig‐zag CuX single chains running parallel to the crystallographic a‐axis which are linked by the 2‐chloropyrazine spacer molecules to sheets parallel to (010). For the iodine compound III a one‐dimensional structure is found which consists of CuX double chains running parallel to the crystallographic a‐axis. The thermic properties of all compounds were investigated in different gas atmospheres using simultaneously differential thermal analysis and thermogravimetry (DTA‐TG) as well as temperature resolved X‐ray powder diffraction. On heating, the 1:1 compounds I and II decompose directly to the corresponding copper(I) Halides, whereas the thermal decomposition of III occcur via IV as an intermediate.