Dinuclear Ring Research Articles

Magnesiacycloalkanes with Different Ring Sizes

Di-Grignard compounds are prepared via the direct synthesis of magnesium with Br2C{Si(CH3)3}2, α,ω-dihalides of XCH2YCH2X (X: Cl, Br; Y: Si(CH3)2, (CH2)n with n = 4, 5, 6), and with ClC(CH3)2(CH2)n(CH3)2CCl (n = 3, 4) in tetrahydrofuran (THF) or diethyl ether. After removal of the sparingly soluble magnesium halides after addition of 1,4-dioxane (dx) the corresponding magnesium alkanediides remain in solution. Only the geminal di-Grignard complex (BrMg)2(μ-C{Si(CH3)3}2) forms the corresponding dioxane adduct [{(dx)2MgBr}2(μ-C{Si(CH3)3}2)] (1). The magnesium alkanediides can be recrystallized from THF and characterized with X-ray crystallography and NMR spectroscopy. Preferably dinuclear rings of the types [(thf)2Mg(μ-CH2-Y-CH2)}2] (Y: Si(CH3)2 (2), (CH2)6 (5)) and [({thf}2Mg{μ-C(CH3)2(CH2)4C(CH3)2})2] (7) crystallize. From a 1 M solution the strand-like coordination polymer [({thf}2Mg{μ-(CH2)6})∞] (3) precipitates. Only [(thf)2Mg{C(CH3)2(CH2)3(CH3)2C}] (6) crystallizes as a mononuclear compound. The NMR s...

Syntheses, crystal structures, and properties of new metal--5-bromonicotinate coordination polymers

Four metal–5-bromonicotinate (Brnic) coordination polymers [Fe(Brnic){sub 2}(H{sub 2}O){sub 2}]{sub n} (1), [Ni(Brnic){sub 2}]{sub n} (2), [Ni(Brnic)(bpy)(H{sub 2}O){sub 2}]{sub n}·n(Brnic)·4.5nH{sub 2}O (3), and [Co{sub 2}(Brnic){sub 3}(bpy){sub 2}(OH)]{sub n}·nH{sub 2}O (4) have been synthesized and structurally characterized (bpy=4,4′-bipyridine). Complex 1 has corrugated (4,4) sheets formed by μ-Brnic ligands and planar nodes Fe(II). As for 2–4, they all built up from Brnic-bridged dinuclear subunits, but have very different structure features. Complex 2 is a twin-like polymer with (4,4) layers formed by twin paddle-wheel [Ni{sub 2}(Brnic){sub 4}] subunits. Through the bridge coordination of bpy ligands with dinuclear rings [Ni{sub 2}(Brnic){sub 2}] and trigons [Co{sub 2}(Brnic){sub 3}(OH)], 6{sup 3}-topological cationic layers with nanosized grids of 3 and chiral ladder-type double chains of 4 formed, respectively. Notably, halogen-related interactions play an important role in the formation of 3D metallosupermolecules 1–4. The thermostabilities of all compounds have been discussed in detail. Moreover, the magnetic investigations of 2 and 4 indicate that there exist antiferromagnetic interactions in the paddle-wheel [Ni{sub 2}(Brnic){sub 4}] and trigon [Co{sub 2}(Brnic){sub 3}(OH)] cores, respectively. - Highlights: • Four novel metal–5-bromonicotinate coordination polymers have been synthesized. • Notably, halogen-related interactions play an important role in the formation of 3D metallosupermolecules. • Antiferromagnetic interactions inmore » nickel(II) paddle-wheel and cobalt(II) trigon cores were observed.« less

Six New Coordination Polymers: from Dimer to 2D Network based on the Combination of cis‐Bis(imidazole) Spacers with Cobalt(II) Cations

AbstractThis paper reports the first systemic investigation on the bimetallic ring coordination polymers based on two structure‐related flexible bis(imidazole) ligands, bimb as well as bix [bimb = 1, 4‐bis(imidazol‐1‐yl)‐butane, bix = 1, 4‐bis(imidazol‐1‐yl‐methylene)‐benzene)]. As expected, six new cobalt complexes were generated, namely, [Co2(SCN)4(bimb)2] (1), [Co2(L1)2(bimb)2Cl2] (2), [Co2(L2)4(bix)2] (3), [Co(SCN)2(bimb)2] (4), {Co[N(CN)2]2(bimb)2} (5), and [Co(L3)(bix)] (6) (HL1 = 4‐aminobenzoic acid, HL2 = 4‐nitrobenzoic acid, and H2L3 = succinic acid). The structures of 1–3 are three discrete dinuclear ring motifs. Especially, 1 is the first example of 1D pseudo‐polyrotaxane formed by S···S strong interactions based on bis(imidazole) ligands. 4 and 5 exhibit 1D meso‐helical chain architecture, in spite of their different space groups. In 6, the discrete dinuclear ring motifs, traversed by μ2‐η3‐chelating L3 anions, are interconnected by another μ2‐η1‐bridging L3 anions to form 2D (4, 4) network. The formation of these compounds should be undoubtedly attributed to the preference for cis‐bis(imidazole) ligands crystallization resulting in various ring architectures. In addition, compound 6 exhibits antiferromagnetic behavior.

A ring-like coordination structure constructed by Cu(II) and bis(2-(pyridin-2-ylthio)ethyl)ether ligand

The reaction of bis(2-(pyridin-2-ylthio)ethyl)ether (L) with CuCl2 in CH3OH/CHCl3 solution gives a novel 24-membered ring-like coordination structure which has been characterized by elemental analysis, IR, and X-ray single-crystal diffraction. The X-ray diffraction analysis reveals that [Cu2L2Cl4] crystallizes in the triclinic, space group \(P\bar 1\). The ring-like structure is consisted of two ligands with two copper ions coordinated to the pyridyl nitrogen atoms from two ligands respectively. The largest diameters of the planarshaped dinuclear ring are about 12.7 A. The adjacent ring-like units are linked via C-H…O hydrogen bonds to generate an infinite linear chain, which are further linked by C-H…Cl hydrogen bonds and weak intermolecular interactions to form a three-dimensional network.

Syntheses, crystal structures and antimicrobial activities of thioether ligands containing quinoline and pyridine terminal groups and their transition metal complexes

Abstract Eleven transition metal complexes of three asymmetrical tridentate thioether ligands, 8-((pyridin-2-yl)methylthio) quinoline (TQMP2), 8-((pyridin-3-yl)methylthio) quinoline (TQMP3), 8-((pyridin-4-yl)methylthio) quinoline (TQMP4) and one symmetrical pentadentate ligand 2,6-bis (8-quinolinylthiomethyl) pyridine (DTQMP) were prepared. The structures of all these complexes were identified by means of elemental analysis (EA), infrared spectra (IR) and single-crystal diffraction, providing three different kinds of basic conformations, (1) discrete mononuclear structures, (2) dinuclear rings and (3) 1D polymer chains. The antibacterial, antifungal and pesticide activities of the four ligands and 11 complexes were also studied.

Controlling self-assembly of zinc(II)-benzoate coordination complexes with 1,4-bis(4-pyridyl)ethane by varying solvent and ligand-to-metal ratio: Their catalytic activities

Abstract Four new coordination polymers formed by zinc-benzoate with the 1,2-bis(4-pyridyl)ethane (bpe) bridging ligand have been prepared and characterized. Zinc-benzoates can be rationally tuned to form four different structures with a bridging bpe ligand by controlling ligand-to-zinc-benzoate molar ratios and by using different solvent systems, and reveal three coordination polymers having similar one-dimensional characteristics but having different mono-, di-, trinuclear nodes (1–3), and a dinuclear ring type molecule (4). This work reveals that the ligand-to-metal ratio and solvent play very important roles in the formation of different coordination structures. We have also shown that the compounds 1–4 catalyzed efficiently the transesterification of a variety of esters. The complex 3 showed the most efficient reactivity and is the best among the catalytic efficiencies reported previously with zinc-containing coordination and polymeric compounds. The substrates with the electron-withdrawing substituents have undergone faster transesterification than those with the electron-donating ones. In addition, the scope of the application of 1–4 as transesterification catalysts has been expanded to now include ethanol and propanol, suggesting that this catalytic system can be potentially useful for preparing various esters by transesterification. Moreover, the transesterification reaction mechanism was discussed by 1H NMR study.

Bis(μ-4-sulfamoylbenzoato)bis[chloro(di-2-pyridylamine)copper(II)] dihydrate

In the title compound, [Cu2(C7H6NO4S)2Cl2(C10H9N3)2]·2H2O, each CuII ion is six-coordinated by three O atoms, viz. carboxyl­ate and sulfamoyl O atoms from two 4-sulfamoylbenzoate anions, by two N atoms from a di-2-pyridylamine ligand, and by a Cl atom. Each pair of CuII ions is bridged by two 4-sulfamoylbenzoate anions and each ion has the same coordination environment, forming a dinuclear ring. The dinuclear complex is centrosymmetric.

Bis(dimethylammonium) di-μ-pyrazole-3,5-dicarboxylato(3–)-bis[aquacopper(II)] monohydrate

In the title compound, (C2H8N)2[Cu2(C5HN2O4)2(H2O)2]·H2O, the cations, anions and water mol­ecules are linked by hydrogen bonds into a network structure. Two pyrazole-3,5-dicarboxyl­ate trianions and one water mol­ecule are coordinated to the CuII ion and the geometry is square-pyramidal. Each pair of CuII ions is bridged by two pyrazole-3,5-dicarboxyl­ate trianions, forming a dinuclear ring.

Syntheses and structures of Ag(I) compounds containing btp ligands

Four new Ag(I) complexes with three different modes of structures were obtained by varying the counteranions (ClO4-for1,PF6-for2,CF3SO3-(OTf-)for3,andCF3CO2-for4), and their structures characterized by single-crystal X-ray diffraction analysis. Compounds 1, 2, and 3 crystalize in the C-centered monoclinic space group C2/m. Compound 4 crystalizes in the monoclinic space group P21/c. The crystal structures of these complexes show that the complexes 1, 2, and 3 form ligand-supported dinuclear rings, and the dinuclear units of 1 and 3 are further linked by anions to form one-dimensional polymer, while the complex 4 forms an one-dimensional zigzag chain. The structural differences between 1, 2, 3, and 4 show the influences of the counteranions on the structures of the complexes.

Novel dithioether–silver(i) coordination architectures: structural diversities by varying the spacers and terminal groups of ligands

An investigation into the dependence of the framework formation of coordination architectures on ligand spacers and terminal groups was reported based on the self-assembly of AgClO4 and eight structurally related flexible dithioether ligands, RS(CH2)nSR (Lan, R = ethyl group; Lbn, R = benzyl group, n= 1-4). Eight novel metal-organic architectures, [Ag(La1)3/2ClO4]n (1a), [Ag2(La2)2(ClO4)2]2 (2a), [AgLa3ClO4]n (3a), {[Ag(La4)2]ClO4}n (4a), [AgLb1ClO4]2 (1b), [Ag(Lb2)2]ClO4 (2b), {[Ag(Lb3)3/2(ClO4)1/2](ClO4)1/2}n (3b) and [Ag(Lb4)3/2ClO4]n(4b), were synthesized and structurally characterized by X-ray crystallography. Structure diversities were observed for these complexes: 1a forms a 2-D (6,3) net, while 2a is a discrete tetranuclear complex, in which the AgI ion adopts linear and tetrahedral coordination modes, and the S donors in each ligand show monodentate terminal and mu2-S bridging coordination fashions; 3a has a chiral helical chain structure in which two homo-chiral right-handed single helical chains (Ag-La3-)n are bound together through mu2-S donors, and simultaneously gives rise to left-handed helical entity (Ag-S-)n. In 4a, left- and right-handed helical chains formed by the ligands bridging AgI centers are further linked alternately by single-bridging ligands to form a non-chiral 2-D framework. 1b has a dinuclear structure showing obvious ligand-sustained Ag-Ag interaction, while 2b is a mononuclear complex; 3b is a 3-D framework formed by ClO4- linking the 2-D (6,3) framework, which is similar to that of 1a, and 4b has a single, double-bridging chain structure in which 14-membered dinuclear ring units formed through two ligands bridging two AgI ions are further linked by single-bridging ligands. In addition, a systematic structural comparison of these complexes and other reported AgClO4 complexes of analogous dithioether ligands indicates that the ligand spacers and terminal groups take essential roles on the framework formation of the AgI complexes, and this present feasible ways for adjusting the structures of such complexes by modifying the ligand spacers and terminal groups.

μ-Aqua-bis(μ-2′-carboxybiphenyl-2-carboxylato-κ2O:O′)bis[bis(2′-carboxybiphenyl-2-carboxylato-κO)(1,10-phenanthroline-κ2N,N′)cobalt(II)

In the title complex, [Co2(C14H9O4)4(C12H8N2)2(H2O)], each Co2+ cation is surrounded by two N atoms from a 1,10-phenanthroline (phen) ligand and four O atoms [one from a water mol­ecule, one from a monodentate 2′-carboxybi­phenyl-2-carboxyl­ate (Hbpdc) ligand and two from two bridging Hbpdc ligands), thus forming a distorted CoO4N2 octahedron. The two Co2+ cations are bridged by two Hbpdc anions via their carboxyl­ate groups to produce an eight-membered dinuclear ring. The Co centres are also bridged by a water molecule, this latter species lying on a twofold axis.

Bis(mu-2-sulfonatobenzoato)bis[(1,10-phenanthroline)lead(II)] dihydrate.

In the title centrosymmetric dimer, [Pb2(sbc)2(phen)2].2H2O [sbc is the 2-sulfonatobenzoate dianion (C7H4O5S) and phen is 1,10-phenanthroline (C12H8N2)], each Pb(II) ion is six-coordinated by four O atoms, viz. carboxylate and sulfonate O atoms from two sbc anions, and two N atoms from a 1,10-phenanthroline ligand. One 1,10-phenanthroline ligand and the carboxylate group of one sbc ligand are chelated to each Pb(II) cation, and the sulfonate group of the other sbc unit is monodentate. One O atom of the chelated carboxylate group also bridges to the other Pb(II) cation, so that each pair of Pb(II) ions is bridged by two sbc anions and has the same coordination environment, forming a dinuclear ring. Each pair of Pb(II) ions is thus connected by two different kinds of bridges, namely a carboxylate short bridge and a carboxylate-sulfonate long bridge. There is also a special position of 1 site symmetry at the centre of the two Pb(II) cations.

Gold(I)-Purine Interactions: Synthesis and Characterization of Cyclic and Open Chain Polynuclear Gold(I) Complexes Containing Xanthine Derivatives and Bis(phosphine) as Bridging Ligands. Crystal Structures of [Au(2)(&mgr;-HX)(&mgr;-dmpe)].3H(2)O and [Au(2)(&mgr;-TT)(&mgr;-dmpe)].H(2)O (H(3)X = Xanthine; H(2)TT = 8-Mercaptotheophylline).

The reaction of [(AuBr)(2)(&mgr;-PR(2)P(CH(2))(n)()PR(2))] (where R = CH(3) for n = 1; R = Ph for n = 1, 3, 4) with N-alkylxanthine and thioxanthine derivatives, containing two ionizable protons in close positions, yields, under basic conditions, neutral heterobridged dinuclear gold(I) ring complexes [Au(&mgr;-L)(2)(&mgr;-PR(2)P(CH(2))(n)()PR(2))], which have been investigated by means of (1)H- and (31)P-NMR and FAB spectroscopies. Crystal structures of two of these complexes are reported. [Au(2)(&mgr;-HX)(&mgr;-dmpe)].3H(2)O (1) (H(3)X = xanthine; dmpe = 1,2-bis(dimethylphosphine)ethane) crystallizes in the monoclinic space group P2(1)/n with a = 9.348(2) Å, b = 8.656(2) Å, c = 24.585(5) Å, beta = 98.24(2) degrees, Z = 4, and R = 0.040. [Au(2)(&mgr;-TT)(&mgr;-dmpe)].H(2)O (2) crystallizes in the monoclinic space group P2(1)/n with a = 10.853(4) Å, b = 14.031(6) Å, c = 13.574(5) Å, beta = 100.80(4) degrees, Z = 4, and R = 0.063. The structures of 1 and 2 are similar and consist of dinuclear nine-membered ring molecules, in which the two linear two-coordinate gold atoms are bridged on one side by a dmpe ligand and on the other side by a bidentate xanthinato dianion, with intramolecular Au.Au distances of 3.053(1) and 2.952 (2) Å, respectively. In the former, the coordination of the xanthinato ligand to the gold atoms takes place through the N3 and N9 nitrogen atoms whereas, in the latter, N7,S8-chelate coordination of the 8-thiotheophyllinato dianion occurs. The magnitude of the Au.Au separation is analyzed in terms of the twisting of the xanthine derivative ligand from the plane containing the gold(I) and phosphorus atoms. For n = 6 the steric requirements of the Au(&mgr;-dpph)Au group prevents the formation of dinuclear ring complexes and open chain complexes are obtained. Finally, when the xanthine derivatives do not contain two close active coordination sites dinuclear open chain complexes are formed.