Four triazole-bridging coordination polymers containing (m-phenol)-1,2,4-triazole: Syntheses, structures and properties of fluorescence and magnetism

Four triazole-bridging coordination complexes, [Zn₄(ptr)₂(SO₄)₃(μ₃-OH)₂(H₂O)₄]_n (1), [Hg(CN)₂(ptr)]_n (2), [Hg(Cl)₂(ptr)]_n (3), and [Cu₂(μ₂-ptr)₂(μ₂-F)₂]_n(SiF₆)_n·2nH₂O (4), were synthesized with (m-phenol)-1,2,4-triazole (ptr). Compounds 1-4 with extended structures of 4-substituted 1,2,4-triazole are rarely reported. The layered structure of 1 can be regarded as constructed from the 2-D inorganic backbone of SO₄²⁻(2) anions bridging [Zn₄(μ₃-OH)₂(H₂O)₂]⁶⁻ subunits with the ptr ligands anchoring to both sides of backbone. Compounds 2 and 3 are the first mercury(II) complexes with 4-substituted 1,2,4-triazole, which feature the ptr ligand acting as a bidentate ligand bridging the Hg(II) atoms to form arciform -Hg-ptr-Hg-ptr chains. The structure of 4 is constructed from the F atoms bridging Cu atoms in symmetrical μ₂-coordination mode to form a zigzag cationic chain with each ptr ligand bridging a pair of Cu atom on the both sides, resulting in a nonplanar 5-membered [Cu₂N₂F] ring. Fluorescent properties of 1-4 were characterized and the magnetic property of 4 shows antiferromagnetic interaction between the copper(II) ions.     

A series of three-dimensional coordination polymers with general formula [{Ln(H2O)n}{Re6Te8(CN)6}] · xH2O (Ln = Eu,Gd, Tb,Dy, Ho,Er, Tm,Yb; n = 3, 4, x = 0, 2.5)

A series of new compounds containing rare earth cations (Eu to Yb) and paramagnetic cluster anion [Re₆Te₈(CN)₆]³⁻ was prepared and investigated. The X-ray structural analyses have revealed that the compounds [{Ln(H₂O)₄}{Re₆Te₈(CN)₆}] · 2.5H₂O; Ln = Eu (1), Tb (3), Dy (4), Ho (5), Er (6), Tm (7), [{Gd(H₂O)₃}{Re₆Te₈(CN)₆}] · 2.5H₂O (2) and [{Yb(H₂O)₄}{Re₆Te₈(CN)₆}] (8) are three-dimensional polymers based on Re–CN–Ln interactions. Measurements of magnetic susceptibility for 2 and 5 showed that effective magnetic moment (at 300 K) was 8.13 μ_B for compound 2 and 10.79 μ_B for compound 5 with weak antiferromagnetic ordering appeared at low temperatures.     

Complexes derived from the copper(II)/succinamic acid/N,N′,N″-chelate tertiary reaction systems: Synthesis,structural and spectroscopic studies

The use of succinamic acid (H₂sucm) in Cu^II/N,N′,N″-donor [2,2′:6′,2″-terpyridine (terpy), 2,6-bis(3,5-dimethylpyrazol-1-yl)pyridine (dmbppy)] reaction mixtures yielded compounds [Cu(Hsucm)(terpy)]_n(ClO₄)_n (1), [Cu(Hsucm)(terpy)(MeOH)](ClO₄) (2), [Cu₂(Hsucm)₂(terpy)₂](ClO₄)₂ (3), [Cu(ClO₄)₂(terpy)(MeOH)] (4), [Cu(Hsucm)(dmbppy)]_n(NO₃)_n·3nH₂O (5^.3nH₂O), and [CuCl₂(dmbppy)]·H₂O (6·H₂O). The succinamate(−1) ligand exists in four different coordination modes in the structures of 1–3 and 5, i.e., the μ₂-κO:κO′:κO″ in 1 and 5 which involves asymmetric chelating coordination of the carboxylato group and ligation of the amide O-atom leading to 1D coordination polymers, the μ₂-κ²O:κO′ in 3 which involves asymmetric chelating and bridging coordination of the carboxylato group, and the asymmetric chelating mode in 2. The primary amide group, either coordinated in 1 and 5, or uncoordinated in 2 and 3, participate in hydrogen bonding interactions, leading to interesting crystal structures. Characteristic IR bands of the complexes are discussed in terms of the known structures and the coordination modes of the Hsucm⁻ ligands. The thermal decomposition of complex 5·3nH₂O was monitored by TG/DTG and DTA measurements.     

Self assembly of asymmetric tetranuclear Cu(II) [2 × 2] grid-like complexes and of a dinuclear Ni(II) complex from pyridyl-phenol Schiff base ligands

Self assembly of N-salicylidene 2-aminopyridine (L1H) with Cu(NO₃)₂·3H₂O affords [Cu₄(L1)₄(NO₃)₃(CH₃OH)][Cu(L1)(NO₃)₂](2-aminopyridinium)(NO₃)·5CH₃OH (1) which is composed of an asymmetric [2 × 2] grid-like cationic complex that co-crystallizes with a Cu(II) mononuclear anion. This remarkable tetranuclear unit presents three penta-coordinated and one hexa-coordinated Cu(II) sites. This quadruple helicate structure reveals strong anti-ferromagnetic coupling (J = −340(2) cm⁻¹) between Cu(II) ions through a double alkoxo bridge. Reacting L1H with Cu(NO₃)₂·3H₂O in slightly different conditions affords however a more symmetric tetranuclear grid-like complex: [Cu₄(L1)₄(NO₃)₂(OH)₂](2-aminopyridinium)(OH)·CH₃OH) (2). A dinuclear Ni(II) complex, [Ni₂(L2)₂(L2H)₂(NCS)₂(CH₃OH)₂]·2CH₃OH (3), obtained with another related donor ligand (L2H = N-salicylidene 3-aminomethylpyridine) was also prepared.     

Dimolybdenum complexes containing anions of N,N′-bis(pyrimidine-2-yl)formamidine and N-(2-pyrimidinyl)formamide

The reactions of Mo₂(O₂CCH₃)₄ with different equivalents of N,N′-bis(pyrimidine-2-yl)formamidine (HL1) and N-(2-pyrimidinyl)formamide (HL2) afforded dimolybdenum complexes of the types Mo₂(O₂CCH₃)(L1)₂(L2) (1) trans-Mo₂(L1)₂(L2)₂ (2) cis-Mo₂(L1)₂(L2)₂ (3) and Mo₂(L2)₄ (4). Their UV–Vis and NMR spectra have been recorded and their structures determined by X-ray crystallography. Complexes 2 and 3 establish the first pair of trans and cis forms of dimolybdenum complexes containing formamidinate ligands. The L1 ligands in 1–3 are bridged to the metal centers through two central amine nitrogen atoms, while the L2 ligands in 1–4 are bridged to the metal centers via one pyrimidyl nitrogen atom and the amine nitrogen atom. The Mo–Mo distances of complexes 1 [2.0951(17) Å], 2 [2.103(1) Å] and 3 [2.1017(3) Å], which contain both Mo?N and Mo?O axial interactions, are slightly longer than those of complex 4 [2.0826(12)–2.0866(10) Å] which has only Mo?O interactions.     

Syntheses,structures and luminescent properties of four d-metal coordination polymers based on the 2,4,5-tri(4-pyridyl)-imidazole ligand

Four d¹⁰-metal coordination polymers based on the 2,4,5-tri(4-pyridyl)-imidazole ligand (Htpim), {[Zn₂(Htpim)₄Cl₄] · 8H₂O}_n (1), {[Cd(tpim)₂(H₂O)₂] · 4CH₃OH}_n (2), {[Cu₂(Htpim)(PPh₃)₂I₂] · CH₃CN}_n (3) and {[Ag(Htpim)](NO₃) · CH₂Cl₂}_n (4), have been synthesized and characterized by elemental analyses, IR, thermogravimetric and X-ray structural analyses. Both complexes 1 and 2 show one dimensional ribbon-like structures. Via intermolecular hydrogen bonds, a 2D supramolecular network and 3D framework are formed for 1 and 2, respectively. Complex 3 shows a 1D zigzag chain with a CuI₂Cu rhomboid dimer. Complex 4 shows a 1D ladder-like polymer with two different metallacycles. The luminescent properties of all the complexes have been studied in the solid state.     

Synthetic,structural and spectroscopic studies of complexes derived from the copper(II) perchlorate/fumaric acid/N,N′-chelates tertiary reaction systems

The synthetic investigation of the Cu(ClO₄)₂·6H₂O/fumaric acid (H₂fum)/N,N’-chelates (1,10-phen, 2,2′-bpy) tertiary reaction systems has yielded mononuclear, dinuclear and tetranuclear complexes, and three coordination polymers. The chemical and structural identity of the products depends on the solvent, the absence or presence of external hydroxides in the reaction mixtures and the N,N’-donor. Three fumarato(−2) complexes, i.e. compounds [Cu₂(fum)(phen)₄](ClO₄)₂·2H₂O (1·2H₂O), [Cu(fum)(phen)(H₂O)]_n (3) and [Cu₂(fum)(bpy)₂(H₂O)₂]_n(ClO₄)_2n (6), were isolated and structurally characterized, and four non-fumarato complexes, i.e. compounds [Cu₄(μ₃-ΟΗ)₂(μ₂-ΟΗ)₂(phen)₄(H₂O)₂](ClO₄)₄·2H₂O (2·2H₂O), [Cu(ClO₄)(phen) (MeCN)₂(H₂O)](ClO₄) (4), [Cu(ClO₄)(phen)(MeCN)₂]_n(ClO₄)_n (5) and [Cu(ClO₄)₂(bpy)(MeCN)₂] (7), were simultaneously obtained from the reaction systems investigated. The coordination versatility of the fumarato(−2) ligand is reflected to the three different coordination modes observed in 1·2H₂O, 3 and 6; the monodentate bridging μ₂-κO:κO′ mode in 3, the asymmetric chelating bridging μ₂-κO:κO′:κO′′:κO′′′ mode in 1·2H₂O and 3, and the syn,syn bridging μ₄-κO:κO′:κO′′:κO′′′ mode in 6. The crystal structures of the complexes are stabilized by intra- and inter-molecular hydrogen bonding and π–π stacking interactions leading to interesting supramolecular architectures. Characteristic IR bands of the complexes are discussed in terms of the known structures, and the coordination modes of the fum²⁻ ligands.     

Novel 1D Cu(I) coordination polymers formed by the combination of Cu(I) halides and 4-(2-pyridyl)pyrimidine

Three novel 1D Cu(I) coordination polymers [Cu₄X₄(pprd)₂]_n (X = Cl(1), Br(2) and I(3); pprd = 4-(2-pyridyl)pyrimidine) were systematically synthesized by Cu(I) halides and the pprd ligand, and they have been characterized by X-ray, IR, and TG-DTA analyses. The molecular structure of complex 1 essentially resembles to that of complex 2. In complexes 1 and 2, four Cu(I) atoms are bridged by four Cl or Br anions to form an eight-membered Cu₄X₄ framework in the twist-chair form. Furthermore, the Cu₄X₄ frameworks are coordinated by the chelate and bridging sites of two pprd ligands to form a unique 1D two-stepped Cu(I) coordination polymer, in which two stairs are formed by the Cu₄X₄ core and two heteroaromatic planes of pprd. In the crystal packing structures, it is interesting that two heteroaromatic planes of pprd are stacking along the b-axis for complex 1 and the a-axis for complex 2. In contrast, four Cu(I) atoms in complex 3 are bridged by four I atoms to form a Cu₄I₄ stepped cubane tetramer. Additionally, the Cu₄I₄ stepped cubane cores are linked by the chelate and bridging sites of two pprd ligands to form an infinite 1D zigzag-chain Cu(I) coordination polymer. The thermal decomposition behaviors for Cu(I)–X/pprd complexes 1, 2 and 3 were determined by thermogravimetric analysis (TG-DTA). Although the thermal decomposition behaviors of complex 1 were unidentified, those of complexes 2 and 3 were assigned. The mass loss at the first stage of thermal decomposition for polymeric [Cu₄X₄(pprd)₂]_n was identical to the formation of oligomeric [Cu₄X₄(pprd)] by the elimination of one pprd molecule. The mass loss at the next stage was decided to the formation of Cu₄X₄ by the elimination of another pprd molecule.     

One-dimensional silver(I) 5,5-diethylbarbiturato coordination polymers with N-piperidineethanol and 1,3-bis(4-piperidyl)propane: Syntheses,crystal structures,spectroscopic and thermal properties

Two new coordination polymers, [Ag₂(barb)(pipet)]_n (1) and {Na₃[Ag₂(barb)₂](pippr)·2H₂O}_n (2) (where H₂barb, pipet and Hpippr are 5,5-diethylbarbituric acid, N-piperidineethanol and 1,3-bis(4-piperidyl)propane, respectively) have been synthesized and characterized by elemental analysis, IR, thermal analysis and X-ray single-crystal diffraction techniques. Silver(I) ions in complexes 1 and 2 are bridged by barb dianions, leading to one-dimensional coordination polymers. In 1, the barb ligand acts as a tetradentate bridging ligand, while in 2 as a bidendate bridging ligand. The pipet ligand behaves as a bidentate chelating donor, whereas the pippr anion is not involved in coordination and remains as a counter-ion. The one-dimensional chains of 1 and 2 are further extended into supramolecular networks. Spectral and thermal analysis data for 1 and 2 are in agreement with the crystal structures.     

Synthesis and characterisation of [AlMen{Si(SiMe3)3}3−n(thf)] (n = 1 or 2)

The crystalline compounds [AlMe_n{Si(SiMe₃)₃}_3−n(thf)] [n = 2 (1) or 1 (2)] were prepared from the lithium sisyl [Li{Si(SiMe₃)₃}(thf)₃] (A) and the appropriate methylaluminium chloride [AlCl_3−nMe_n] in thf. The X-ray structure of 1 is reported. Unlike A or a magnesium sisyl [Mg{Si(SiMe₃)₃}₂(thf)₂] (B), neither 1 nor 2 underwent an insertion reaction with an α-H-free nitrile.     

Assembly molecular architectures based on structural variation of metalloligand [Cu(PySal)2] (PySal = 3-pyridylmethylsalicylideneimino)

A versatile neutral metalloligand [Cu(PySal)₂] (1) (PySal = 3-pyridylmethylsalicylidene-imino) was exploited as a building unit to construct five complexes {Cu[Cu(PySal)₂]₂}(ClO₄)₂ (2), {Cd[Cu(PySal)₂]₂(H₂O)₂]} (NO₃)₂ · 2H₂O · 4CH₃OH (3), {Zn[μ₂-Cu(PySal)₂]Cl₂}_n · nCH₃OH (4), {Hg[μ₂-Cu(PySal)₂]I₂}_n (5) and {Cd[μ₂-Cu(PySal)₂]Cl₂}_n · nCH₂Cl₂ (6). [Cu(PySal)₂] acts as a chelating ligand in discrete complexes 2 and 3 with unbound anions, but as a bis-monodentate bridging ligand in polymers 4, 5 and 6 when halogen anions coordinated cooperatively to metal cations. The coordination geometry of Cu²⁺ is well-defined square planar in bridging [Cu(PySal)₂], analogous to that in free metalloligand (1), but it is distorted square planar in chelating [Cu(PySal)₂].     

“Wheel-and-axle” binuclear Cu(II) dioximates mediated by 1,2-bis(4-pyridyl)ethane: Synthesis, X-ray study and luminescent properties

The reaction of copper(II) acetate or fluoride with classic dioximes in the presence of 1,2-bis(4-pyridyl)ethane resulted in four novel compounds with the compositions [Cu₂(dmgH)₄bpe] (1), [Cu₂(NioxH)₄bpe] (2), [Cu₂(dpgH)₄bpe] (3), and [Cu₂(dpgH)₄bpe][Cu(dpgH)₂bpe]₂·2DMF (4) (where dmgH₂ = dimethylglyoxime, NioxH₂ = 1,2-cyclohexanedionedioxime, dpgH₂ = diphenylglyoxime, bpe = 1,2-bis(4-pyridyl)ethane, and DMF = N,N′-dimethylformamide), whose crystal structures were determined by single crystal X-ray diffraction. In the binuclear molecules 1-3, as well as in both binuclear and mononuclear molecules in 4 each Cu(II) atom has an identical N₅-environment formulated by four oximic nitrogen atoms of two monodeprotonated ligands in a slightly distorted square planar mode, and the nitrogen atom of the bpe molecule being in the apical position. The new compounds were characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Luminescence investigations for 1, 2 and 4 were carried out to clarify whether the guest inclusion in the crystal lattice is accompanied by changes in the emission spectra.     

Syntheses, crystal structures and luminescent properties of two novel lanthanide/4-pya complexes: [Ln(4-pya)3(H2O)2]2 (Ln = Eu, La; 4-pya = trans-4-pyridylacrylate)

Reactions of Ln₂O₃ and trans-4-pyridylacrylic acid (4-Hpya) in EtOH/H₂O or MeOH/H₂O produced two new lanthanide/4-pya complexes [Ln(4-pya)₃(H₂O)₂]₂ (1: Ln = Eu; 2: Ln = La) in low yields. However, reactions of LnCl₃ · 6H₂O with 4-Hpya/aqueous ammonia in EtOH/H₂O or MeOH/H₂O gave rise to 1 or 2 in higher yields. Both compounds were structurally characterized by elemental analysis, IR spectroscopy and X-ray analysis. Compounds 1 · 2EtOH · 2H₂O and 2 · 2MeOH · 2H₂O were confirmed to possess one-dimensional polymeric chain structures. In the structure of 1, each Eu(III) adopts a monocapped square-antiprism coordination geometry and each dimer [Eu(4-pya)₃(H₂O)₂]₂ within the chain is interconnected by two pairs of different bridging 4-pya ligands. On the other hand, each La(III) of 2 takes a bicapped square-antiprism coordination geometry and each dimer [La(4-pya)₃(H₂O)₂]₂ within the chain is linked by two pairs of tridentate bridging 4-pya ligands. The luminescent properties of 1 and 2 in the solid state were investigated.     

Syntheses and crystal structures of cadmium(II)X2-hexamethylenetetramine (X = Br/I/SCN) coordination polymers having different dimensionality

Four new coordination polymers of cadmium(II) with hexamethylenetetramine (htm) have been synthesized and characterized by routine physicochemical techniques as well as by X-ray single crystal structure analysis. They are [CdBr(htm)(SCN)(H₂O)₂·CH₃OH]_n (1), [CdI(htm)(SCN)(H₂O)₂·0.5(CH₃OH)]_n (2), [Cd₂(htm)₃(SCN)₄(H₂O)]_n·nH₂O (3) and [Cd₃Br₆(htm)₂(H₂O)₅·(htm)(H₂O)₆]_n (4). Complexes 1, 2 and 3 exhibit 1D polymeric structure and complex 4 shows a 2D undulated layered arrangement, containing Cd₆(htm)₆ hexagonal units as building block, which extended to a 3D supramolecular architecture through hydrogen bonding. Thorough thermal investigation suggest that as far as the thermal stability of Cd(II)-htm bond is concerned it attains the maximum in complex 1 and minimum in complex 4. In case of complex 3 the thermal study inferred that CdS end product was obtained at ∼730 °C, whereas in case of other complexes the thermally stable end product remained unidentified. Solid state fluorescence study shows that all the complexes are luminescent at room temperature except complex 3.     

New cationic palladium (II) and rhodium (I) complexes of [Ph2PCH2C(Ph)N(2,6-Me2C6H3)]

Treatment of the bulky iminophosphine ligand [Ph₂PCH₂C(Ph)N(2,6-Me₂C₆H₃)] (L) with [M(CH₃CN)₂(ligand)]⁺ⁿ, where for M = Pd(II): ligand = η³-allyl, n = 1, and for M = Rh(I), ligand: 2(C₂H₄), 2(CO) or cod, n = 0, yields the mono-cationic iminophosphine complexes [Pd(η³-C₃H₅)(L)][BF₄] (1), [Rh(cod)(L)][BF₄] (2), [Rh(CO)(CH₃CN)(L)][BF₄] (3), and cis-[Rh(L)₂][BF₄] (4). All the new complexes have been characterised by NMR spectroscopy and X-ray diffraction. Complex 1 shows moderate activity in the copolymerisation of CO and ethene but is inactive towards Heck coupling of 4-bromoacetophenone and n-butyl acrylate.     

Synthetic, X-ray structural and protonation studies of CpCr(CO)2SPy and CpCr(CO)2SPym (SPy = C5H4NS, SPym = C4H3N2S)

The facile reaction of [CpCr(CO)₃]₂ (Cp = η⁵-C₅H₅) (1) with one mole equivalent of 2,2′-dithiodipyridine ((C₅H₄NS)₂(SPy)₂) at ambient temperature led to the isolation of dark brown crystalline solids of CpCr(CO)₂(η²-SPy) (2) in ca. 72% yield. 2 undergoes quantitative conversion to CpCrCl₂(η¹-SPyH) (3) with HCl. The reaction 1 with one mole equivalent of 2-mercaptopyrimidine (C₄H₃N₂SHHSPym) at ambient temperature led to the isolation of reddish-brown crystalline solids of CpCr(CO)₂(η²-SPym) (4) and green solids of CpCr(CO)₃H (5) in yields of ca. 42% and 46%, respectively. Reaction of 4 with HCl and subsequent workup in acetonitrile resulted in the cleavage of the thiolate ligand, giving the 15-electron chromium(III) species CpCrCl₂(CH₃CN) (6) and free 2-mercaptopyrimidine. The complexes 2-4 have been determined by single X-ray diffraction analysis.     

Syntheses, crystal structures and magnetic properties of two dicopper(II) complexes and a zigzag 1-D Cu(II) complex of a bidentate pyridyl-pyrazole ligand

Two new dinuclear copper compounds, [Cu₂(pypz)₂(N₃)₂(NO₃)₂] (1) and [Cu₂(pypz)₂(OH)₂(NO₃)₂] (2), and one 1-D polymeric Cu(II) complex, [Cu(pypz)(dca)₃]_n (3) [‘pypz’ = (3,5dimethyl-1-(2′-pyridyl)pyrazole) and dca = (dicyanamide)], have been synthesized and characterized crystallographically and spectroscopically. Complex 1 is pseudo-octahedral, adjacent Cu atoms are connected by a pair of μ(1,1) azido groups and the structure is stabilized by π-π interactions between two pyridyl moieties from two different neighboring complex molecules. Complexes 2 and 3 are square pyramidal. The hydroxo bridged complex 2 is further stabilized through H-bonding. The 1-D polymeric chain of 3 is bridged by an end-to-end dicyanamide bridge and it propagates along the crystallographic b axis, whilst the polymer chains are stacked one upon another along the crystallographic c axis. Low temperature magnetic measurement shows that complexes 1 and 2 are ferromagnetic (J values are 30.81 and 14.79 cm⁻¹, respectively), whereas due to larger Cu-Cu distances, complex 3 shows weak ferromagnetism.     

A systematic investigation of the CuCl2/H2mal/phen reaction system (H2mal = malonic acid): Solution and solid state studies of its products

The systematic investigation of the parameter space of the CuCl₂/H₂mal/phen reaction system in MeOH resulted in the isolation of seven different complexes either as mixtures or in pure form, six of which have been structurally characterized. The molar ratios of the reactants and the crystallization methods have been systematically varied, leading to the isolation of compounds [Cu(H₂O)(phen)(mal)] (1), [Cu(MeOH)(phen)(mal)] (2), [Cu₂Li₂Cl₂(phen)₂(mal)₂(MeOH)₄] (3), [Cu₂(phen)₄(mal)][CuCl(phen)(mal)](OH) (4), [CuCl(phen)₂]Cl (5), and [CuCl(phen)(mal)][CuCl(phen)₂][Cu(phen)₂(Hmal)]Cl (6). The coordination versatility of the malonato ligand has been confirmed by the presence of three different coordination modes and its two deprotonation states in compounds 1–6. Solution studies on methanolic solutions of 2–4 and 6 by mass spectrometry revealed the absence of parent ion peak and the presence of fragment ions of low relative abundance not previously found in their crystal structure, thus indicating decomposition and rearrangement/reorganization of the complexes in solution and confirming the dynamic character of their solutions. Compounds 3 and 4 have been also studied in the solid state by EPR spectroscopy and magnetic measurements.