Syntheses and crystal structures of two copper(I)-halide π,σ-coordination compounds based on 2-[(prop-2-en-1-yl)sulfan-yl]pyridine.

The title compounds, di-µ-chlorido-bis-({2-[(η-2,3)-(prop-2-en-1-yl)sulfan-yl]pyridine-κN}copper(I)), [Cu2Cl2(C8H9NS)2], and di-µ-bromido-bis-({2-[(η-2,3)-(prop-2-en-1-yl)sulfan-yl]pyridine-κN}copper(I)), [Cu2Br2(C8H9NS)2], were obtained by alternating-current electrochemical synthesis starting from an ethano-lic solution of 2-[(prop-2-en-1-yl)sulfan-yl]pyridine (Psup) and the copper(II) halide. The isostructural crystals are built up from centrosymmetric [Cu2 Hal 2(Psup)2] dimers, which are formed due to the π,σ-chelating behavior of the organic ligand. In the crystals, the dimers are linked by C-H⋯Hal hydrogen bonds as well as by aromatic π-π stacking inter-actions into a three-dimensional network.

Synthesis, structure and computational study of 5-[(prop-2-en-1-yl)sulfanyl]-1,3,4-thiadiazol-2-amine (Pesta) and its heterometallic π,σ-complex [Cu2FeCl2(Pesta)4][FeCl4].

Copper(I) π-coordination compounds with allyl derivatives of azoles are an interesting subject of current research, but CuI π-complexes with other transition-metal ions incorporated in the structure have been virtually uninvestigated. The present work is directed toward the synthesis and structural characterization of the novel heterometallic CuI/FeII π-complex di-µ2-chlorido-1:2κ2Cl;2:3κ2Cl-tetrakis[µ2-5-(prop-2-en-1-ylsulfanyl)-1,3,4-thiadiazol-2-amine]-1:2κ2N4:N3;1(η2),κN4:2κN3;2:3κ2N3:N4;2κN3:3(η2),κN4-dicopper(I)iron(II) tetrachloridoferrate(II), [Cu2FeCl2(C5H7N3S2)4][FeCl4] (1). The structure of the 5-[(prop-2-en-1-yl)sulfanyl]-1,3,4-thiadiazol-2-amine (Pesta, C5H7N3S2) ligand is also presented. The cationic substructure in 1 consists of one FeII and two CuI ions bridged by two chloride ions along with two σ,σ- and two π,σ-coordinated ligands, whereas the anionic part is built of isolated tetrahedral [FeCl4]2- ions. π-Coordination of the Pesta allyl group to the CuI ions prevents agglomeration of the inorganic Cu-Cl-Fe-Cl-Cu part into infinate chains. An energy framework computational analysis was performed for Pesta.

Crystal structure, Hirshfeld surface analysis and computational studies of 5-[(prop-2-en-1-yl)sulfan-yl]-1-[2-(tri-fluoro-meth-yl)phen-yl]-1H-tetra-zole.

The title compound, C11H9F3N4S, was synthesized from 2-(tri-fluoro-meth-yl)aniline by a multi-step reaction. It crystallizes in the non-centrosymmetric space group Pna21, with one mol-ecule in the asymmetric unit, and is constructed from a pair of aromatic rings [2-(tri-fluoro-meth-yl)phenyl and tetra-zole], which are twisted by 76.8 (1)° relative to each other because of significant steric hindrance of the tri-fluoro-methyl group at the ortho position of the benzene ring. In the crystal, very weak C-H⋯N and C-H⋯F hydrogen bonds and aromatic π-π stacking inter-actions link the mol-ecules into a three-dimensional network. To further analyse the inter-molecular inter-actions, a Hirshfeld surface analysis, as well as inter-action energy calculations, were performed.

Synthesis and Structure of [Cu(Hapn)]NO3]NO3, [Cu(Hapn)(H2O)2]SiF6, [Cu(Hapn)(H2O)BF4]BF4 · H2O and [Cu(Hapn)(NH2SO3)2] π-complexes (apn = 3-(prop-2-en-1-ylamino)propanenitrile).

Four copper(I) π-complexes: [Cu(Hapn)NO3]NO3 (1), [Cu(Hapn)(H2O)2]SiF6 (2), [Cu(Hapn)(H2O)BF4]BF4·H2O (3) and [Cu(Hapn)(NH2SO3)2] (4) were prepared using alternating-current electrochemical technique, starting from alcohol solutions of 3-(prop-2-en-1-ylamino)propanenitrile (apn) titrated with appropriate acid and copper(II) salts (Cu(NO3)2 · 3H2O, CuSiF6 · 4H2O, Cu(BF4)2 · 6H2O or Cu(NH2SO3)2 · xH2O, respectively). Obtained compounds were characterized by single-crystal X-ray diffraction and partially by IR spectroscopy. In the structures of complexes 1, 2 and 4 Cu(I) cation possesses a tetrahedral environment formed by the C=C bond of one organic cation Hapn, the N atom of cyano group from another Hapn moiety, and two O atoms (from NO3- anions in 1, from H2O molecules in 2) or N atoms (NH2SO3- anions in 4). In compound 3 strongly pronounced trigonal-pyramidal coordination environment of Cu(I) is formed by a mid-point of C=C-bond of one Hapn cation, nitrogen atom (of cyano group) of another Hapn unit, O atom of H2O molecule in the basal plane, and F atom of BF4- anion at the apical position.

Ligand-forced dimerization of copper(I)-olefin complexes bearing a 1,3,4-thiadiazole core.

As an important class of heterocyclic compounds, 1,3,4-thiadiazoles have a broad range of potential applications in medicine, agriculture and materials chemistry, and were found to be excellent precursors for the crystal engineering of organometallic materials. The coordinating behaviour of allyl derivatives of 1,3,4-thiadiazoles with respect to transition metal ions has been little studied. Five new crystalline copper(I) π-complexes have been obtained by means of an alternating current electrochemical technique and have been characterized by single-crystal X-ray diffraction and IR spectroscopy. The compounds are bis[µ-5-methyl-N-(prop-2-en-1-yl)-1,3,4-thiadiazol-2-amine]bis[nitratocopper(I)], [Cu2(NO3)2(C6H9N3S)2], (1), bis[µ-5-methyl-N-(prop-2-en-1-yl)-1,3,4-thiadiazol-2-amine]bis[(tetrafluoroborato)copper(I)], [Cu2(BF4)2(C6H9N3S)2], (2), µ-aqua-bis{µ-5-[(prop-2-en-1-yl)sulfanyl]-1,3,4-thiadiazol-2-amine}bis[nitratocopper(I)], [Cu2(NO3)2(C5H7N3S2)2(H2O)], (3), µ-aqua-(hexafluorosilicato)bis{µ-5-[(prop-2-en-1-yl)sulfanyl]-1,3,4-thiadiazol-2-amine}dicopper(I)-acetonitrile-water (2/1/4), [Cu2(SiF6)(C5H7N3S2)2(H2O)]·0.5CH3CN·2H2O, (4), and µ-benzenesulfonato-bis{µ-5-[(prop-2-en-1-yl)sulfanyl]-1,3,4-thiadiazol-2-amine}dicopper(I) benzenesulfonate-methanol-water (1/1/1), [Cu2(C6H5O3S)(C5H7N3S2)2](C6H5O3S)·CH3OH·H2O, (5). The structure of the ligand 5-methyl-N-(prop-2-en-1-yl)-1,3,4-thiadiazol-2-amine (Mepeta), C6H9N3S, was also structurally characterized. Both Mepeta and 5-[(prop-2-en-1-yl)sulfanyl]-1,3,4-thiadiazol-2-amine (Pesta) (denoted L) reveal a strong tendency to form dimeric {Cu2L2}2+ fragments, being attached to the metal atom in a chelating-bridging mode via two thiadiazole N atoms and an allylic C=C bond. Flexibility of the {Cu2(Pesta)2}2+ unit allows the CuI atom site to be split into two positions with different metal-coordination environments, thus enabling the competitive participation of different molecules in bonding to the metal centre. The Pesta ligand in (4) allows the CuI atom to vary between water O-atom and hexafluorosilicate F-atom coordination, resulting in the rare case of a direct CuI...FSiF52- interaction. Extensive three-dimensional hydrogen-bonding patterns are formed in the reported crystal structures. Complex (5) should be considered as the first known example of a CuI(C6H5SO3) coordination compound. To determine the hydrogen-bond interactions in the structures of (1) and (2), a Hirshfeld surface analysis has been performed.

Two Related Copper(I) π-Complexes Based on 2-Allyl-5-(2-pyridyl)-2H-tetrazole Ligand: Synthesis and Structure of [Cu(2-apyt)NO3] and [Cu(2-apyt)(H2O)](BF4) Compounds.

By means of the alternating current electrochemical technique two new π-compounds [Cu(2-apyt)NO3] (1) and [Cu(2-apyt)(H2O)](BF4) (2) have been obtained starting from the mixture of 1-allyl-5-(2-pyridyl)-2H-tetrazole (1-apyt), 2-allyl-5-(2-pyridyl)-2H-tetrazole (2-apyt) and corresponding copper(II) salts, and have been structurally studied. Selective complexation towards 2-allyl- isomer results in a formation of 2-apyt complexes. Copper(I) ion in both 1 and 2 complexes coordinates the allylic C=C bond, one pyridyl and one tetrazole N atoms. In both structures Cu+ center adopts distorted tetrahedral surrounding which additionally includes oxygen of NO3(-) in 1 and H2O moiety in 2. Structure 1 is built from [Cu(2-apyt)NO3]2 dimeric fragments. Contrary, participation of H2O in the metal coordination in 2 leads to the infinite {[Cu(2-apyt)(H2O)]+}n chain construction. To analyze interactions between the particles in 1 and 2 Hirshfeld surface analysis was performed.

First N-allyl-aminothiadiazole copper(I) π-complexes: synthesis and structural peculiarities of [Cu(L)CF3SO3] and [Cu2(L)2(H2O)2](SiF6) · 2.5H2O compounds (L = 2-(allyl)-amino-5-methyl-1,3,4-thiadiazole).

By means of alternating current electrochemical technique two crystalline copper(I) π-complexes with fluorine containing anions [Cu(L)CF3SO3] (1) and [Cu2(L)2(H2O)2](SiF6)2 · 2.5H2O (2) (L - 2-(allyl)-amino-5-methyl-1,3,4-thiadiazole) have been obtained and characterized by X-ray single crystal diffraction and Raman spectroscopy. In both structures the organic molecule L acts as chelate-bridging tridentate ligand being connected to copper(I) by two N atoms of thiadiazole ring and C=C bond from allyl group resulting in a formation of stable cationic dimers [Cu(L)2]2+. In the structure 1 oxygen atom from triflate-anion occupies an apical position of the metal coordination polyhedron, while in 2 located far from the metal centre hexafluorosilicate anion allows an appearance of the H2O molecule in copper environment. Hydrogen bonds (D)-H···A (where D = O, N, C; A = O, F) play a significant role in formation of 2D- (1) and 3D- (2) frameworks.

Synthesis and Crystal Structure of Copper(I) Nitrate π-complex with 1-allylbenzotriazole of Equimolar Composition.

The CuNO3 • C6H4N3(C3H5) compound (I) was obtained by alternating current electrochemical synthesis, starting from an ethanol solution containing Cu(NO3)2 • 3H2O and a mixture of 1- and 2-allylbenzotriazole titrated by HNO3 to pH = 4. The C=C bond of one 1-allylbenzotriazole molecule, the nitrogen atom from another ligand moiety, and two oxygen atoms from two nitrate-anions form a trigonal-pyramidal environment of the metal atom. The bridging function of the ligand moiety results in infinite metal-organic chains, interconnected by weak CH…O hydrogen bonds, π-π and π-σ stacking and van der Waals interactions.

Bis[bis-(3,5-diamino-1H-1,2,4-triazol-4-ium)copper(I)] tris-(hexa-fluoridosilicate).

In the title compound, [Cu(C(2)H(6)N(5))(2)](2)(SiF(6))(3), the asymmetric unit is composed of one [Cu(HL)(2)](3+) cation (where L is 3,5-diamino-1,2,4-triazole) and one and a half SiF(6) (2-) anions. The rather large positively charged guanazole ligand moiety promotes the low metal coordination number of 2 for the Cu(I) atom. The compound was obtained using the electrochemical alternating-current technique starting from an ethanol-methanol solution of CuSiF(6)·4H(2)O and guanazole. In the crystal, N-H⋯F hydrogen bonds play an important role in the formation of a three-dimensional network. As a result of these hydrogen bonds, there are also π-π inter-actions [centroid-centroid distance = 3.3024 (14) Å] involving one of the triazole groups in mol-ecules related by an inversion center, and short Cu⋯N inter-actions [2.909 (3) Å] involving an -NH(2) group, leading to the formation of a dimer-like arrangement.

Bis(diallyl-benzimidazolium) tetra-bromidocuprate(II).

The structure of the title ionic copper(II) compound, (C(13)H(15)N(2))(2)[CuBr(4)], is built up of isolated 1,3-diallyl-benzimidazolium cations and [CuBr(4)](2-) anions which are inter-connected by electrostatic inter-actions. Differences in packing of the heterocyclic cores results in a different structure compared with earlier investigated chloride and bromide analogues.

catena-Poly[[cyclo-tetra-mu-chlorotetracopper(I)]-bis{mu-3-[(2-morpholino-4-oxo-4,5-dihydro-1,3-thiazol-5-ylidene)methylphenoxy]propene}-2kappaN,1'eta2;1eta2,2'kappaN].

Crystals of a new copper(I) complex of composition [Cu4Cl4(C17H18N2O3S)2]n have been obtained by alternating-current electrochemical synthesis. In the crystal structure, the Cu and Cl atoms form a chair-like Cu4Cl4 cyclic fragment. The organic ligand acts as a bridge, being connected via the C=C bond of the allyl group to a Cu atom from one inorganic cycle and via the N atom of the thiazole ring to a Cu atom of another copper-chloride fragment. The geometry of the pi center indicates that the Cu-(C=C) interaction is moderately effective.

catena-Poly[bis[(eta2-1-allyl-3-aminopyridinium)copper(I)]-di-mu-chloro-copper(I)-di-mu-chloro-copper(I)-di-mu-chloro].

Crystals of the title pi-complex, [Cu4Cl6(C8H11N2)2]n, were obtained by means of alternating-current electrochemical synthesis. The structure consists of infinite copper-chlorine chains to which 1-allyl-3-aminopyridinium moieties are attached via a eta2 Cu-(C=C) interaction. The two independent Cu atoms have distinct coordination environments. One is three-coordinate, surrounded by two chloro ligands and the olefinic bond, whereas the second copper center is surrounded by a tetrahedral arrangement of four Cl atoms. The lower basicity of 3-aminopyridine as compared with 2- and 4-aminopyridine lowers the capacity of the organic ligand for donating to N-H...Cl hydrogen bonds and results in the formation of a large inorganic fragment.

Influence of Cl/Br substitution on the stereochemical peculiarities of copper(I) pi-complexes with the 1-allyl-2-aminopyridinium cation.

By using alternating-current electrochemical synthesis, crystals of the Cu(I) pi-complexes bis(1-allyl-2-aminopyridinium) di-micro-chloro-bis[chlorocopper(I)], (C(8)H(11)N(2))(2)[Cu(2)Cl(4)] or [H(2)NC(5)H(4)NC(3)H(5)][CuCl(2)], and bis(1-allyl-2-aminopyridinium) di-micro-(chloro/bromo)-bis[(chloro/bromo)copper(I)], (C(8)H(11)N(2))(2)[Cu(2)Br(2.2)Cl(1.8)] or [H(2)NC(5)H(4)NC(3)H(5)][CuBr(1.10)Cl(0.90)], have been obtained and structurally investigated. In each of the isostructural (isomorphous) compounds, the distorted tetrahedral Cu environment involves three halide atoms and the C=C bond of the ligand. Both compounds reside on inversion centres, and the dimeric [Cu(2)X(4).2H(2)NC(5)H(4)NC(3)H(5)] units are bonded into a three-dimensional structure by N-H...X hydrogen bonds. The Br content in the terminal X1 position is much higher than that in the bridged X2 site.