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.     

Syntheses and luminescence of four supramolecular coordination complexes with flexible ligand

Four d ¹⁰-based complexes with chemical formulae {[Zn(L¹)₂(H₂O)₂(4,4′-Bipy)₂] (I), {[Zn₂(L¹)₄(Mi)] · 4H₂O} (II), {[Zn(L¹)₂(Phen)] · H₂O} (III) {[Cd(L¹)₂(Phen)] · 2H₂O} (IV) (HL¹ = p-hydroxy phenylacetic acid, 4,4′-Bipy = 4,4′-bipyridine, Phen = 1,10-phenanthroline, Mi = 1,4-bis(imidazol-1-yl)butane) have been synthesized and structurally characterized by single crystal X-ray diffraction (CIF files CCDC nos. 1047119 (I), 1047120 (II), 1047121 (III), 1047122 (IV)). The significant effect of assistant ligands and metal ions on assembly of I?IV has been demonstrated, which leads to the formation of distinct crystalline products. Complexes I?IV show various coordination motifs with different existing forms and coordination modes of the organic ligands. Furthermore, extend supramolecular networks are connected by secondary interactions such as hydrogen-bonding and aromatic stacking. The thermal stability and luminescent properties of the compounds were discussed in detail.     

Construction of [Cu n I n ]-based coordination polymers via flexible benzimidazolyl-based ligands

Four new [Cu _n I _n ]-based coordination polymers, [{ Cu₄(µ₃-I)₄(mbbm)₂}·2DMF] _n (1), [(CuI)₂(mbbm)₂] _n (2), [{Cu₂(µ-I)₂-(ebbm)₂}·2MeCN] _n (3), and [Cu₂(µ-I)₂(prbbm)₂] _n (4), were prepared from solvothermal reactions of CuI with three flexible ligands [(bzim)(CH₂) _n (bzim)] (bzim = benzimidazole; n = 1, mbbm; n = 2, ebbm; n = 3, prbbm). These compounds were characterized by elemental analysis, IR and X-ray crystallography. 1 consists of cubanelike [Cu₄(µ₃-I)₄] fragments that link the neighboring ones via mbbm bridges to form a 1D ladder-type chain. 2 contains mononuclear [CuI] fragments that are bridged by mbbm ligands to yield a 1D zigzag chain. 3 or 4 contains a [Cu₂(µ-I)₂] dimeric fragment, which works as a four-connecting node to link its four equivalent ones to form a 2D (4,4) network (3) or acts as a two-connecting node to connect its two equivalent ones via two pairs of prbbm bridges to form a 1D double chain (4). The photoluminescent properties of 1–4 in the solid state at ambient temperature were investigated.     

Between MOFs and molecules: organolead(IV) compounds with chain structures

Organolead compounds are of interest mainly as catalysts and organolead halides have proved to be very efficient materials for solar cells. Two organolead(IV) dimethylarsinates, namely catena‐poly[[triphenyllead(IV)]‐μ‐chlorido‐[triphenyllead(IV)]‐μ‐dimethylarsinato‐κ²O:O′], [Pb₂(C₆H₅)₆(C₂H₆AsO₂)Cl]_n or [(Ph₃Pb)₂Cl(O₂AsMe₂)], ( 1 ), and poly[chlorido(μ₃‐dimethylarsinato‐κ³O:O,O′:O′)diphenyllead(IV)], [Pb(C₆H₅)₂(C₂H₆AsO₂)Cl]_n or [(Ph₂ClPb)(O₂AsMe₂)], ( 2 ), together with the triphenyllead(IV) diphenylphosphinate catena‐poly[[triphenyllead(IV)]‐μ‐diphenylphosphinato‐κ²O:O′], [Pb(C₆H₅)₃(C₁₂H₁₀O₂P)]_n or [(Ph₃Pb)(O₂PPh₂)], ( 3 ), have been synthesized and characterized by single‐crystal X‐ray diffraction, IR spectroscopy and mass spectrometry. In ( 1 ), a chain structure was found with alternating chloride and Pb—O—As—O—Pb arsinate bridges between five‐coordinate Pb^IV atoms. In ( 2 ), bidentate and chelate‐like bonded dimethylarsinate ligands form double chains with heptacoordinated Pb^IV atoms. In ( 3 ), a pentacoordinated Pb^IV atom is connected by Pb—O—P—O—Pb phosphinate bridges to form a linear chain. Obviously, the steric demand of the phenyl ligands at Pb^IV reduces the possibility of interconnections via polydentate ligands to one dimension only. Thus, no metal–organic frameworks (MOF) are formed but instead various chain structures are observed.     

36-Nuclear anionic cobalt(II) and nickel(II) complexes in solid-phase insertion reactions

The reactions of single crystals containing 36-nuclear anionic complexes of cobalt(II), (NBu₄)₈[Co₃₆(H₂O-κO)₁₂(μ₃-OH)₂₀(μ₄-Me₂Mal-κ₂O,O′)₂₄(μ₄-Me₂Mal)₆] · 2.5H₂O ? CH₃OH (I), and nickel(II), (NBu₄)₈[Ni₃₆(H₂O-κO)₁₂(μ₃-OH)₂₀(μ₄-Me₂Mal-κ₂O,O′)₂₄(μ₄-Me₂Mal)₆] · 6H₂O ? 2C₂H₅OH (II) and (NHEt₃)₃[Ni₃₆(NHEt₃)(H₂O-κO)_12.25(μ₃-OH)₂₀(μ₄-HMe₂Mal-κ₂O,O′)₄(μ₄-Me₂Mal-κ₂O,O′)₂₀(μ₄-Me₂Mal)₆] · 39H₂O (III), with solutions of 1,4-dioxane and a 0.1 M solution of Dabco (Dabco is 1,4-diazabicyclo[2.2.2]octane) in EtOH are studied. An ethanol solution of Dabco dissolves the crystals of the complexes, whereas the insertion of the solvent molecules with single crystal retention (for the cobalt compound containing tetrabutylammonium cation, I), cracking (for the nickel analog, II), or dissolution (for the cobalt complex containing triethylammonium, III) occurs in 1,4-dioxane. The X-ray diffraction analyses show the substitution of the uncoordinated water and ethanol molecules in the starting compound by 1,4-dioxane molecules in the structure of compound I to form (NBu₄)₈[Co₃₆(H₂O-κO)₁₂(μ₃-OH)₂₀(μ₄-Me₂Mal-κ₂O,O′)₂₄(μ₄-Me₂Mal)₆] · 7C₄H₈O₂ (IV), which is accompanied by a change in the conformation and the shift of tetrabutylammonium cations, indicating a possibility of the modification of the 36-nuclear d-metal complexes with the malonic acid derivatives in the solid-phase resolvation reactions (CIF files CCDC no. 1557499 (III) and 1557500 (IV)).     

Synthesis,Crystal Structure,and Properties of a 2D Cu(I) Coordination Polymer Based on Cu<Subscript>3</Subscript>I<Subscript>3</Subscript> Chains Linked by 1,3-Di-(1,2,4-Triazole-4-yl)Benzene

A new copper(I) iodide coordination polymer, [(CuI)₃(dtb)] _n (1) (dtb = 1,3-di-(1,2,4-triazole-4-yl)benzene) has been synthesized solvothermally and structurally characterized by single crystal and powder X-ray diffractions, elemental analysis, IR, and thermogravimetric analysis. Overall, 1 exhibits a 2D hybrid structure containing dtb as structure-directing agents (SDAs) and 1D Cu₃I₃ chain as inorganic moiety. The copper-iodide chain can be regarded as two Cu₂I₂ rhomboids are connected by CuI fragments via Cu–I bonds. Dtb act as bridging ligands regularly link the Cu₃I₃ chains along both sides through Cu–N bonds to give the final 2D network. Moreover, solid state luminescent property of 1 has been investigated at room temperature.     

Phosphine free diamino-diol based palladium catalysts and their application in Suzuki-Miyaura cross-coupling reactions

Inexpensive air and moisture stable diamino-diol ligands [(2-OH-C₁₀H₆)CH₂(μ-NC₄H₈N)CH₂(C₁₀H₆-2-OH)] (1) and [(5-^tBuC₆H₃-2-OH)CH₂(μ-NC₄H₈N)CH₂(5-^tBuC₆H₃-2-OH)] (2) were synthesized by reacting corresponding alcohols with formaldehyde and piperazine. Treatment of ligands 1 and 2 with Pd(OAc)₂ in 1:1 molar ratio afforded neutral palladium complexes [Pd{(OC₁₀H₆)CH₂(μ-NC₄H₈N)CH₂(C₁₀H₆O)}] (3) and [Pd{(5-^tBuC₆H₃-2-O)CH₂(μ-NC₄H₈N)CH₂(5-^tBuC₆H₃-2-O)}] (4) in good yield. The palladium complexes 3 and 4 are employed in Suzuki-Miyaura cross-coupling reactions between phenylboronic acid and several aryl chlorides or bromides. They are found to be competent homogeneous catalysts for a variety of substrates to afford the coupled products in good to excellent yields. The crystal structures of compounds 2 and 4 are also reported.     

Reactions of Chalcogenide β-Diiminate Nickel Complexes with Samarium Bis(pentamethylcyclopentadienide)

The reactions of [(L^iPrNi)₂(μ-η²:η²-S₄)] (I) and [(L^iPrNi)₂(μ-η²:η²-Se₂)] (II) (L^iPr = CH[C(Me)N(2,6- ⁱ Pr₂C₆H₃)]₂) with decamethylsamarocene [Sm(Cp*)₂(Тhf)₂] (Cp* = η⁵-C₅Me₅) are studied. It is assumed that the reactions afford hetero-d/f-metal complexes. However, these complexes are not observed but the transfer of chalcogens from Ni to Sm and the formation of [(Sm(Cp*)₂(Тhf))₂(μ-S)] (III) and [(Sm(Cp*)₂(Тhf))₂(μ-Se)] (IV) occur. The second reaction products are [(L^iPrNi)₂(μ-η²:η²-S₂)] (V) in the case of sulfur and [(L^iPrNi^I)₂(μ-η⁶:η⁶-C₇H₈)₂] (VI) in the case of selenium. All reaction products have been described previously, but compounds III and V are isolated as new crystalline phase, the structures of which are determined by X-ray diffraction analysis (CIF files CCDC nos. 1559045 (V) and 1559046 (III)).     

Association of copper(II) isonicotinamide moieties via different anionic bridging ligands: Two paths of ferromagnetic interaction in the azide coordination compound

Three isonicotinamide (isn) copper(II) complexes with different bridging ligands, azide, thiocyanate and sulfate, have been prepared. The molecular structure of [Cu₂(μ-1,1-N₃)₂(μ-1,3-N₃)₂(isn)₂]_n (1) is composed of binuclear species, Cu₂(μ-1,1-N₃)₂(isn)₂, inter-connected by additional four azide bridges in the end-to-end mode (1,3). This gives a CuN₄N square-pyramidal coordination sphere around each copper(II) ion. A trans mononuclear octahedral coordination sphere CuN₄S₂ is present in [Cu(μ-N,S-NCS)₂(isn)₂]_n (2), with thiocyanato ligands serving as bridges between the adjacent Cu(isn)₂ moieties. The third anionic ligand, i.e. sulfate, in {[Cu(μ-O,O’-SO₄)(H₂O)(isn)₂]·2H₂O}_n (3) completes the CuO₂N₂O square-pyramidal coordination sphere, and thus enables bridging between the mononuclear Cu(H₂O)(isn)₂ moieties. The ligands that bridge the principal building blocks, i.e. binuclear in 1 and mononuclear in 2 and 3, connect the axial ligands with the equatorial positions of the copper(II) coordination spheres in all three cases. A ferromagnetic interaction FM is found for 1, while 2 and 3 are paramagnetic. Therefore, the key structural difference between 1 on one hand, and 2 and 3 on the other, is found in the anionic ligand, serving in 1 also as the intra-binuclear bridge, showing the main path (J₁) for the FM interaction. Additionally, the inter-binuclear pathway in 1 gives another contribution (J₂) to the whole FM interaction seen herein (J₁ = 18.5 cm^–1, J₂ = 4.9 cm^–1).     

Syntheses and characterization of ferrocenylthiocarboxylate-containing coordination compounds for nonlinear optics

Four metal-organic coordination compounds containing ferrocenylthiocarboxylate components, [Cd₂(η²-SOCFc)₂(η¹-μ₂-SOCFc)₂(4,4′-bpy)]_n (1), [Cd(SOCFc)₂(tmp)]_n (tmp = 4,4′-trimethylene-dipyridine) (2) [Zn(SOCFc)₂(2,2′-bpy)] (3), and {[Hg(SOCFc)₂(phen)] · (0.5CH₃OH)} (4) (Fc = (η⁵-C₅H₅)Fe(η⁵-C₅H₄)), have been prepared in search of good nonlinear optical (NLO) materials. Investigation of the NLO properties shows that Hg-containing compound 4 exhibits very strong third-order NLO absorptive and refractive effects. The NLO absorptive coefficient α₂ value (2.11 × 10⁻¹⁰ m W⁻¹) is larger than those of all the reported ferrocenylcarboxylate-containing coordination compounds and comparable to the well-performing Hg-containing complexes. Additionally, we further analyzed their NLO behaviors through studying electrochemical properties of the four compounds.     

The Cu(II) complexes with bis(pyrazole-1-yl)methane and its derivatives: Synthesis,crystal structure,and magnetic properties

The procedures for the synthesis of the Cu(II) complexes with bis(pyrazole-1-yl)methane (L¹), bis(3,5-dimethyl-4-bromopyrazole-1-yl)methane (L²), and bis(3,5-dimethyl-4-iodopyrazole-1-yl)methane (L³) of the composition Cu₂(L¹)₂Br₄ (I), Cu₂(L²)₂Cl₄ (II), Cu(L³)(NO₃)₂ (III), and Cu(L³)(H₂O)(NO₃)₂ · 2H₂O (IV) were developed. The organic ligands in the above complexes are coordinated to Cu(II) in a bidentate cyclic type through the N(2), N(2′) atoms of the pyrazole rings. The molecular and crystal structures of L², L³, II, III, and IV were determined by X-ray diffraction. The study of the μ_eff(T) function in a temperature interval 2–300 K showed that compound I, which exhibited ferromagnetic exchange interactions in the chains, undergoes transition to antiferromagnetic state with weak ferromagnetism. The exchange antiferromagnetic interactions predominate in compound II.     

Syntheses,steric hindrance effects,luminescent properties and TD-DFT calculations for a series of copper(I) iodide coordination complexes

A series of copper(I) coordination complexes, CuI(Phen)[2-(Dpp)bp] (1) (Phen?=?phenanthroline, 2-(Dpp)bp?=?2-(Diphenylphosphino)-biphenyl), Cu₂I₂(Phen)[2-(Dpp)bp] (2), CuI(2-PBI)[2-(Dpp)bp] (3) and (2-PBI?=?2-(pyridin-2-yl)-1H-benzo[d]imidazole) and CuI(Bipy)[2-(Dpp)bp] (Bipy?=?2,2′-bipyridine) (4) have been synthesized. X-ray crystal structure studies revealed that complexes 1, 3 and 4 showed mononuclear structures with the copper atoms coordinated by iodide, a chelating nitrogen-donor ligand, and a monodentate phosphine ligand. However, the coordination centers display different distortions of their tetrahedral geometries, according to the steric hindrance of the bulky phosphine ligands. Complex 2 has a dinuclear structure, with trigonal and tetrahedral coordination centers. Variations in the aromatic system of the N-heterocyclic ligands result in different luminescence properties. Thus, the emission maxima for these complexes range from 580 to 642 nm, with lifetimes of τ?=?0.6–0.9 and 1.6–4.2 μs. TD-DFT calculations reveal the origin of the luminescence to be metal–ligand charge transfer, as well as halogen–ligand charge transfer. The optical absorption spectra and thermal stabilities of the complexes have also been studied.     

Cobalt complexes supported by salicylichydrazono derivative ligands and various coordination solvents

We report the synthesis and molecular solid-state structures of five novel Co^II and Co^III mononuclear complexes supported by the 2-salicyloylhydrazono-1,3-dithiolane (L1) and 2-salicyloylhydrazono-1,3-dithiane (L2) ligands. Moreover, one novel diamagnetic μ-oxo dinuclear Co^III complex [Co^III₂(HL)₄(μ-O)₂] supported by the ligand L1 was stabilized and characterized. Crystal structure of the supporting ligand L2 was also determined.     

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.     

Group 12 metal coordination polymers of 1,2-bis(diphenylphosphino)ethane dioxide: A persistent 1D chain motif and consequent 2D and 3D architectures

A series of group 12 metal coordination polymers with 1,2-bis(diphenylphosphino)ethane dioxide (dppeO₂), {[ZnCl₂(μ-dppeO₂)]·CH₂Cl₂}_n (1·CH₂Cl₂), [ZnBr₂(μ-dppeO₂)]_n (2), [CdI₂(μ-dppeO₂)]_n (4), [(HgI₂)₂(μ-dppeO₂)]_n (5), [Zn(SCN)(μ-SCN)(μ-dppeO₂)]_n (6), and [Cd(NO₃)(μ-SCN)(μ-dppeO₂)]_n (7), have been synthesized and structurally characterized. The structures of the compounds are all based on an infinite 1D chain constructed by four-coordinate metal ions and dppeO₂ ligands adopting the trans bridging coordination fashion. In the coordination polymers 1, 2 and 4, the halide ions act as terminal ligands, leading to discrete 1D chains with alternative MX₂ and dppeO₂ repeating units. The mercury compound 5 features a unique square-wave-like inorganic chain –[Hg(1)–I–Hg(2)–I]–, and the 1D HgI₂(μ-dppeO₂) chains are further linked by HgI₂ bridges to form a 3D network. In the thiocyanate-containing compounds 6 and 7, the 1D chains are linked by one (6) or two (7) bridging SCN^– ions to result in 2D layered structures. Solid-state emission spectra of the coordination polymers show different variations compared to the free dppeO₂ ligand, such as enhancement (1, 2, 6 and 7), shift (3 and 4) and quenching (5) upon metal coordination.     

Syntheses,X-ray structures and properties of a dinuclear cadmium(II)azido and a polymeric cadmium(II)thiocyanato compounds containing bis(tridentate) congregators

One-pot reactions of cadmium(II) perchlorate/nitrate, Schiff bases (pbap/pfap) and pseudohalides (sodium azide/ammonium thiocyanate) in a 2:1:4 molar ratio in MeOH–MeCN solvent mixtures at room temperature result in a dinuclear compound [Cd₂(pbap)(OH₂)₂(N₃)₄] (1) [pbap = N-(1-pyridin-2-ylbenzylidene)-N-[2-(4-{2-[(1-pyridin-2-ylbenzylidene)amino]ethyl}piperazin-1-yl)ethyl]amine] and a polymeric compound [Cd₂(pfap)(μ_1,3-NCS)(μ_1,3-SCN)(NCS)₂]_n (2) [pfap = N-(1-pyridin-2-ylformylidene)-N-[2-(4-{2-[(1-pyridin-2ylformylidene)amino]ethyl}piperazin-1-yl)ethyl]-amine]. X-ray crystal structural analyses reveal a bis(tridentate) congregation behaviour of the hexadentate blocker (pbap/pfap) encapsulating two metal centers. Each cadmium(II) center in 1 and 2 is in a distorted octahedral geometry with CdN₅O and CdN₅S chromophores, respectively. In 1, the dinuclear units participate in intermolecular O–H?N hydrogen bonding between bound water O atoms and terminal azide N atoms, in combination with C–H?π interactions, resulting in a 3D supramolecular network with an intramolecular Cd?Cd distance of 6.473(2) Å. In the crystal lattice, the covalent 1D chain of 2 is further engaged in face-to-face π?π interactions from two terminal pyridine rings, which stabilizes the chain with an intradimer Cd?Cd separation of 6.640(5) Å. Both the complexes display intraligand ¹(π–π^∗) fluorescence and intraligand ³(π–π^∗) phosphorescence in glassy solutions.     

Solid state synthesis and characterization of a triple chain calcium(II) coordination polymer showing two different bridging 4-nitrobenzoate coordination modes

The solid state reaction of [Ca(H₂O)₄(η¹-4-nba)(η²-4-nba)] 1 (4-nba = 4-nitrobenzoate) with 2-methylimidazole (L²) at 100 °C results in the formation of a Ca(II) coordination polymer [Ca(H₂O)(L²)(4-nba)₂]_n2. Compound 2 was characterized by elemental analysis, spectral and thermal methods, and its structure determined. The coordination polymer 2 crystallizes in the centrosymmetric monoclinic space group P2₁/n with all atoms situated in general positions and its structure consists of a central Ca(II), a monodentate 2-methylimidazole, a bridging water ligand (μ₂-H₂O), a bidentate bridging (μ₂-η¹:η¹) 4-nba ligand and a monoatomic bridging (μ₂-η²) 4-nba ligand. Each seven-fold coordinated Ca(II) in the title compound is bonded to a nitrogen atom of a terminal 2-methylimidazole (L²) ligand, two symmetry related water molecules and four symmetry related 4-nba ligands, resulting in a distorted pentagonal bipyramidal {CaO₆N} polyhedron. Due to the bridging nature of the aqua and 4-nba ligands [(2-methylimidazole)calcium(II)] units in 2 are linked into a one-dimensional coordination polymer consisting of three chains, all of which propagate along b-axis. In the triple chain coordination polymer a Ca···Ca separation of 3.8432(3) Å is observed between neighbouring Ca(II) ions. The oxygen atoms of the carboxylate and nitro functionalities of the 4-nba ligand and the coordinated water are involved in O–H···O, N–H···O and C–H···O interactions. A comparative study of nine alkaline-earth 4-nitrobenzoate compounds is described.     

Synthesis and structures of 3-sila-β-diketiminato complexes of the coinage metals

The dimeric copper(I) 3-sila-β-diketiminate [Cu{(N(R)C(Ar))₂SiR}]₂ · (thf) (1) was obtained from CuI and [Li{(N(R)C(Ar))₂SiR}(thf)₂] (B) in toluene (R = SiMe₃, Ar = C₆H₃Me₂-2,6). When [CuI(PPh₃)₃] was used as a starting material, the LiI-containing compound [Cu{Si(R)(C(Ar)N(R))₂Li(μ-I)}(PPh₃)] (2) was isolated. The reaction of [MI(PPh₃)_n] (M = Ag, n = 3; M = Au, n = 2) with two equivalents of B in toluene gave the isomorphous silver and gold 3-sila-β-diketiminates [M{Si(R)(C(Ar)N(R))₂Li}₂(μ-I)] [M = Ag (3), Au (4)]. Each of 1-4 was characterised by the multinuclear NMR spectroscopy and single-crystal X-ray diffraction crystallography.     

A hexanuclear discrete assembly and a two dimensional coordination polymer constructed from heterotrinuclear [(CuL)2Zn]2+ nodes and dicyanamide spacer (H2L = salen type Schiff base ligands)

Two new Cu(II)–Zn(II) complexes as a discrete hexanuclear cluster [{(CuL¹)₂Zn}₂(μ_1,5-N(CN)₂)₂](ClO₄)₂ (1) and a two dimensional (2D) coordination polymer [(CuL²)₂Zn(μ_1,5-N(CN)₂)₂]_n (2) have been isolated by mixing two similar tetradentate Schiff bases H₂L¹ (N,N′-bis(ɑ-ethylsalicylidene)-1,3-propanediamine) and H₂L² (N,N′-bis(salicylidene)-1,3-pentanediamine) separately with Cu(ClO₄)₂·6H₂O, Zn(ClO₄)₂·6H₂O and NaN(CN)₂ ?at same reaction condition. The heterometallic complexes have been structurally characterized by single crystal X-ray analyses showing that both are formed by angular trinuclear nodes and μ_1,5-dicyanamide spacers. The trinuclear nodes ([(CuL¹)₂Zn]²⁺ in 1 and [(CuL²)₂Zn]²⁺ in 2 are produced in situ from their corresponding reactants. The two Schiff base ligands coordinating the Cu(II) ions through the N₂O₂ donor set are additionally bonded to a Zn(II) ion with the four phenoxido oxygen atoms that act as bridging atoms. The zinc ion completes its coordination geometry with two terminal nitrogen atoms of two different dicyanamide spacers. The orientation of spacers from zinc ion are convergent in 1 whereas divergent in 2. Thus, two [(CuL¹)₂Zn]²⁺ nodes are interconnected by double μ_1,5-dicyanamide bridges via Zn(II) centres to form discrete hexanuclear assembly of complex 1. On the other hand, [(CuL²)₂Zn]²⁺ nodes in 2 are joined by μ_l,5-dicyanamide that bridge Zn(II) to Cu(II) centres of symmetry related units in order to construct a 2D coordination polymer. Consequently, the final coordination environment around Zn(II) is octahedral in both complexes whereas that around Cu(II) are square planar and square pyramidal in 1 and 2 respectively.     

Luminescent Cu(I) and Ag(I) coordination polymers: Fast phosphorescence or thermally activated delayed fluorescence

By applying two donor-acceptor motif molecules, 5,10-di(pyridin-4-yl)-5,10-dihydrophenazine (L1) and 10,10'-di(pyridin-3-yl)-10H,10'H-9,9'-spiroacridine (L2), as ligands and CuI/AgCF₃CO₂ as metal salt, we synthesized three coordination polymers, namely, {Cu₄(L1)₂I₄} (CP1), {Cu(L2)I·CHCl₃} (CP2) and {Ag(L2)CO₂CF₃·CHCl₃} (CP3). X-ray crystallographic analysis revealed that three coordination polymers all feature one-dimensional (1D) linear chains which are consisting of molecular boxlike units. In comparison with low photoluminescence quantum yield (PLQY) of two ligands, three coordination polymers, CP1, CP2 and CP3, present more intense photoluminescence with PLQY of 15%, 46% and 34% at room temperature respectively. The PL emission of CP1 and CP2 at room temperature could be attributed to the fast phosphorescence with lifetime both around 5 μs due to effective intersystem crossing (ISC). Whilst, it is worth noting that CP3 exhibit thermally activated delayed fluorescence (TADF) emission at room temperature.