Solvent-dependent luminescent Cu(I) framework based on 5-(4-pyridyl)tetrazole

A new Cu(Ι) coordination compound, Cu₄(L)₄·2EtOH (1), has been obtained from the solvothermal reaction of CuBr, HL (L=5-(4-pyridyl) tetrazole), EtOH and NH₃·H₂O. The structure determination reveals that 1 has a 2D network, where each Cu(I) atom adopts a trigonal coordination mode. The 2D networks stacked in an ABAB sequence through the π–π interaction to form a 3D supramolecular framework, giving a 1D channel along the b-axis. The TGA and powder XRD measurements reveal that the framework is stable after removal of the guest molecules. Gas (N₂) adsorption measurement was carried out for the framework. Framework 1 shows II sorption profile with N₂, which indicates that N₂ molecules cannot diffuse into the micropore and only surface adsorption occurs. The photoluminescent research shows that compound 1 displays an interesting solvent-dependent luminescence.     

Influence of dicarboxylic acids on self-assembly process: Syntheses and structural characterization of new Ag(I) complexes derived from mixed ligands

Using the principle of crystal engineering, three new silver metal–organic coordination polymers, [Ag₂(L1)₂(L2)]·2H₂O (1), [Ag₂(L1)₂(L3)]·H₂O (2), [Ag₂(L1)₂(L4)]·2H₂O (3) (L1 = 2-aminopyrimidine, L2 = oxalate anion, L3 = glutarate anion and L4 = 1,4-naphthalenedicarboxylate anion) have been synthesized by solution phase reactions of silver nitrate with various dicarboxylic acids and cooperative heterocyclic 2-aminopyrimidine ligand under the ammoniacal conditions. All the complexes have been characterized by elemental analyses, IR spectra and X-ray diffraction. In complex 1, L1 ligands are coordinated to Ag(I) metal centers in rare tridentate fashions, forming one-dimensional (1-D) ladder-like structure, which is interlinked by L2 anions to generate 2-D pleated molecular sheet. Complex 2 displays an interesting two-dimensional (2-D) tongue-and-groove structure containing a new kind of “T-shaped” unit. Meanwhile, each of 2-D bilayers is interlocked by four adjacent identical motifs to form three-dimensional (3-D) 5-fold interpenetrating conformation with weak Ag···Ag interactions. In complex 3, L1 ligands are coordinated to the Ag(I) ions to form 1-D polymeric chain. And L4 anions, acting as bridging linkers through corresponding μ²-carboxylates, link a pair of Ag(I) atoms from adjacent chains to yield 3-D supramolecular network. The structures of complexes 1–3 which span from 2-D to 3-D networks suggest that dicarboxylate anions play important role in the formation of such coordination architectures.     

Novel M(II)–Hg(II) coordination polymers generated from metal-containing building blocks M(2-pyrazinecarboxylate)2 · (H2O)2 (M=Cu, Ni, Co) and HgCl2

A new class of M(II)–Hg(II) (M=Cu(II), Co(II), Ni(II)) mixed-metal coordination polymers, Cu(2-pyrazinecarboxylate)₂HgCl₂ (4), [Co(2-pyrazinecarboxylate)₂(HgCl₂)₂] · 0.61H₂O (5) and [Ni(2-pyrazinecarboxylate)₂(HgCl₂)₂] · 0.77H₂O (6), have been prepared by self assembly of metal-containing building blocks, M(2-pyrazinecarboxylate)₂ · (H₂O)₂(M=Cu(II), Co(II), Ni(II)), with HgCl₂. Compounds 4–6 were characterized fully by IR, elemental analysis and single crystal X-ray diffraction. Compound 4 crystallized in the monoclinic space group C2/c, with a=17.916(5) Å, b=7.223(2) Å, c=13.335(4) Å, β=128.726(3)°, V=1346.2(6) ų, Z=4. It contains alternating Hg(II) and Cu(II) metal centers that are cross-linked by 2-pyrazinecarboxylate spacers and chlorine co-ligands to generate a unique three-dimensional Hg(II)–Cu(II) mixed metal framework. Compound 5 crystallized in the triclinic space group P , with a=6.3879(7) Å, b=6.6626(8) Å, c=13.2286(15) Å, α=96.339(2)°, β=91.590(2)°, γ=113.462(2)°, V=511.71(10) ų, Z=1. Compound 6 also crystallized in the triclinic space group P , with a=6.3543(8) Å, b=6.6194(8) Å, c=13.2801(16) Å, α=96.449(2)°, β=92.263(2)°, γ=113.541(2)°, V=506.67(11) ų, Z=1. Compounds 5 and 6 are isostructural and in the solid state the Hg(II)M(II)Hg(II) units are connected by Hg₂Cl₂ linkages to produce a novel M(II)–Hg(II) (M=Co(II), Ni(II)) zigzag mixed-metal chain, in which a new type of M–M′–M′–M array was observed. The metal containing building blocks, M(2-pyrazinecarboxylate)₂ · (H₂O)₂ (M=Cu(II), Co(II), Ni(II)), exhibit different connectivities to HgCl₂ depending on the metal cation contained within them.     

The C–HCl2Cu(II) synthon in the structural direction and assembly of supramolecular complexes with the 3,3′-bis(2-benzimidazolyl)-2,2′-dipyridine ligand and its N-substituted derivatives

Three new Cu(II) supramolecular complexes [Cu(L₁)Cl₂]·2DMF (1), [Cu(L₂)Cl₂] (2) and [Cu(L₃)Cl₂]·DMF (3) (L₁ = 3,3′-bis(2-benzimidazolyl)-2,2′-dipyridine, L₂ = 3,3′- bis(N-ethyl-2-benzimidazolyl)-2,2′-dipyridine and L₃ = 3,3′-bis(N-benzyl-2-benzimidazolyl)-2,2′-dipyridine) have been prepared and characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. X-ray structural analysis of L₁, L₂·3.5H₂O and L₃·H₂O indicates that all three ligands adopt the trans conformation with the two benzimidazole fragments located on opposite sides of the dipyridyl backbone. While in complexes 1–3, all the ligands display the cis conformation and behave as bidentate chelating reagents to coordinate with Cu(II). The inorganic chloride ions always act as a reliable hydrogen bonded acceptor in these structures, and the resulting C–HCl₂Cu supramolecular synthons play a significant role in the formation and stabilization of the structures. Moreover, additional non-covalent interactions, such as C–Hπ, are also identified to extend the discrete (0-D) or low-dimensional (1-D) motifs into high-dimensional architectures.     

Investigation of the zinc(II) acetylacetonate/benzotriazole reaction system in the presence of bridging N,N′-ligands: Pentanuclear, enneanuclear and polymeric complexes

The reaction of Zn(acac)₂ with btaH (1,2,3-benzotriazole) in dmf yielded the pentanuclear complex [Zn₅(bta)₆(acac)₄(dmf)]·dmf (1·dmf). In the presence of pyrazine, the pentanuclear [Zn₅(bta)₆(acac)₄(dmf)]·3.7dmf (2·3.7dmf) and enneanuclear [Zn₉(bta)₁₂(acac)₆]·6dmf (3·6dmf) complexes were formed, whereas in the presence of 4,4′-bpy the 1D coordination polymer [Zn(acac)₂(4,4′-bpy)]_n (4) was isolated. The molecular structures of 1·dmf and 2·3.7dmf reveal that the [Zn₅] clusters consist of four Zn^II ions which span the corners of a tetrahedron and the fifth resides at its centre. The molecular structure of 3·6dmf reveals that the [Zn₉] clusters consist of two corner sharing tetrahedra and the structure can be described as the addition of two [Zn₅] clusters of 1·dmf and/or 2·3.7dmf followed by the simultaneous abstraction of [Zn(acac)₂] and dmf molecules; this alternative was accomplished by recrystallization of 1·dmf from dmf which yielded 3·6dmf. Each of the μ₃-κN:κN′:κN′′ benzotriazolate ligands in 1·dmf, 2·3.7dmf and 3·6dmf spans an edge of the tetrahedron. The molecular structure of 4 reveals mononuclear [Zn(acac)₂] units bridged via 4,4′-bpy molecules to 1D coordination polymer. Characteristic IR bands of the four complexes are discussed in terms of the coordination modes of the ligands and known structures.     

2-Benzothiazolylthioacetic acid and 4,4′-bipyridine as ligands in designing low-dimensional coordination polymers: Synthesis, architectures and magnetic properties

The combined use of 4,4′-bipyridine (4,4′-bipy) and 2-benzothiazolylthioacetic acid (HBTTAA) as ligands with Mn(II), Cd(II), Co(II) and Cu(II) ions afforded six polymeric complexes, namely {[Mn₃(BTTAA)₄(4,4′-bipy)₄](ClO₄)₂ · 2H₂O}_n (1), [Mn(BTTAA)₂(4,4′-bipy)₂]_n (2), [Cd(BTTAA)₂(4,4′-bipy)₂]_n (3), [Cd(BTTAA)(4,4′-bipy)(NO₃)(H₂O)]_n (4), [Co(BTTAA)₂(4,4′-bipy)(H₂O)₂]_n (5) and [Cu(BTTAA)₂(4,4′-bipy)]_n (6). All these complexes have been characterized by a combination of analytical, spectroscopic and crystallographic methods. Complex 1 is a novel 2D network formed by two different 4⁴ grid networks, whereas isomorphous complexes 2 and 3 exhibit a 2Dl coordination architecture formed by the same 4⁴ grid network. In 4–6, extended 1D chains are formed, with the 4,4′-bipy molecules acting as rigid rod-like links between adjacent metal centers. The carboxylato groups of BTTAA in these complexes exhibit four different coordination modes, namely monodentate, chelating, bridging and bridging-chelating modes. The magnetic properties of 1, 2, 5 and 6 were investigated in the temperature range 2.0–300.0 K. Variable temperature magnetic susceptibility measurements show weak antiferromagnetic interactions in these complexes.     

Synthesis and characterization of copper(II) complexes with 3-methylpicolinic acid. Crystal and molecular structure of bis (3-methylpicolinato- N,O )(4-picoline)copper(II)

Copper(II) complexes of 3-methylpicolinic acid (3-MepicH), namely [Cu(3-Mepic)₂] · 2H₂O (1) and [Cu(3-Mepic)₂(4-pic)] (2) were prepared and characterized by IR spectroscopy and thermal analysis (TGA/DTA). Crystal structure for 2 was determined by X-ray crystal structure analysis. 1 was prepared by reaction of copper(II) sulfate pentahydrate and 3-methylpicolinic acid in aqueous solution, while 2 was prepared by recrystallization of 1 from 4-picoline solution. Structure analysis revealed square-pyramidal copper(II) coordination and N,O-chelating mode of 3-methylpicolinic acid in 2. Copper(II) is coordinated by two 3-Mepic ligands in the basal plane of a square pyramid and by 4-picoline in the apical position. Crystal packing of 2 is dominated by weak intermolecular C–H ··· O hydrogen bonds and π ··· π stacking interactions forming a complex three-dimensional supramolecular architecture.     

Synthetic and structural studies of metal complexes derived from tris(3,5-bimethyl-pyrazolylmethyl)amine and pyridine derivatives

A series of metal complexes with a tripodal ligand, TMPzA, have been synthesized and characterized, and their single crystal structures have been determined by X-ray diffraction techniques. It has been found that when pyridyl derivatives as auxiliary ligands are added to the reaction mixture, the tripodal ligand TMPzA loses a pendant arm and coordinates with the metal centers to form the complexes: [Cu(DMPzA)(2,2′-bipy)]·(ClO₄)₂ (1), [(DMPzA)Cu(μ-4,4′-bipy)Cu(DMPzA)]·(ClO₄)₄ (2), [(TMPzA)Cu(μ-H₂DPC)Cu(DMPzA)]·(ClO₄)₂ (3), [(DMPzA)Co(μ-H₂DPC)Co(TMPzA)]·(ClO₄)₂ (4) [TMPzA = tris(3,5-bimethyl-pyrazolymethyl)amine; bipy = bipyridine; H₂DPC = pyridyl-2,6-bicarboxylate; DMPzA = bis(3,5-bimethyl-pyrazolmethyl)amine]. In order to investigate the effect of the pyridyl ring on the cleavage of the pendant arm in the tripodal ligand, a fifth complex, [(TMPzA)Co(μ-HZPC)Co(TMPzA)·(H₂O)₂]·(ClO₄)₃ (5), has been prepared by using pyrazole-carboxylate (HZPC) instead of pyridyl derivatives, and its crystal structure has been determined. It has been found that the pendant arm in TMPzA ligand has not been removed in complex 5. The results show that the complexes with TMPzA have a strong ability to recognize pyridine compounds in methanol solvent, and they have potential application for molecular devices in the future. The cleavage mechanism has been studied by DFT calculations and ESI-MS spectra.     

Preparation,Structure, Spectral,and Magnetic Properties of Copper(II) Halogenonicotinates: Crystal and Molecular Structure of Tetrakis(μ‐2‐chloronicotinato‐O,O′)‐diaquadicopper(II)

The characterization of the complexes [Cu₂(2‐Clnic)₄(H₂O)₂] ( 1 ), [Cu(2,6‐Cl₂nic)₂(H₂O)₂] ( 2 ) and [Cu(5‐Brnic)₂(H₂O)₂]_n ( 3 ) (where 2‐Clnic = 2‐chloronicotinate, 2,6‐Cl₂nic = 2,6‐dichloronicotinate or 5‐Brnic = 5‐bromonicotinate) was based on elemental analysis, IR, electronic and EPR spectra, and magnetic susceptibility. Complex 1 was also studied by X‐ray analysis at 298 1a and 80 K 1b . The complex 1 contains a dinuclear Cu‐acetate molecular structure in which the carboxyl groups of the 2‐chloronicotinate ligands act as bridges and water molecules are at apical positions. The stereochemistry about Cu atom at both temperatures is typical for square pyramidal geometry with CuO₄O chromophore. The Cu‐Cu distance is 2.6513(8) and 2.6382(6) Å for 1a and 1b , respectively. The Cu atoms are displaced by 0.2069(9) and 0.1973(7) Å, respectively, from the plane containing four oxygen atoms bonded to the Cu atom toward the apical water molecules. Strong and weak hydrogen bonds as well as C–Cl···π interactions in the crystal structure are discussed as well. Both complexes, monomeric [Cu(2,6‐Cl₂nic)₂(H₂O)₂] ( 2 ) and polymeric [Cu(5‐Brnic)₂(H₂O)₂]_n ( 3 ), possess octahedral copper(II) stereochemistry with differing tetragonal distortions.     

η-Pentamethylcyclopentadienylruthenium(II) complexes containing η-coordinated α-amino acids

Reaction of [Cp* RuCl₂]₂ with -alanine ( -alaH) in methanol at room temperature in the presence of NaOMe yields the complex Na[Cp* RuCl( -ala)] (1), which contains a five-membered N,O-coordinated chelate ring. The analogous complex Na[Cp* RuCl( -phe)] (2) is obtained under similar conditions but at 0°C in 90% yield. At temperatures above 20°C both 2 and the η⁶-coordinated complex [Cp* Ru( -pheH)]Cl (4) are obtained, with the proportion of the latter increasing with temperature. Compound 4 is obtained in 88% yield by refluxing [Cp* RuCl₂]₂ and -phenylalanine ( -pheH) in CH₃OH/CH₃ONa followed by separation from 2. The analogous ruthenium(II) sandwich complexes 5–10 were obtained from -tyrosine and -tryptophane and various derivatives. [Cp* Ru( -met)] (3), prepared by the reaction of [Cp* RuCl₂]₂ with -methionine ( -metH) in CH₃OH/CH₃ONa, displays N,O,S-coordination.     

Solid state coordination chemistry of copper(II)/α-hydroxycarboxylato/2,2′-bipyridine systems

Four new two-ligand complexes of copper(II) with 2,2′-bipyridine and one of three different α-hydroxycarboxylic acids (lactic, H₂LACO; 2-methyllactic, H₂MLACO; and mandelic, H₂MANO) were prepared. Complexes 1–3 of general formula [Cu(HL)₂(bipy)]·nH₂O (HL=monodeprotonated acid), were characterized by elemental analysis, IR, electronic and EPR spectroscopy, magnetic measurements and thermogravimetric analysis. Complexes 1 (HL=HLACO, n=2), 2 (HL=HMLACO, n=1) and 3a (the result of attempted recrystallization of 3, of formula [Cu(HMANO)(bipy)₂](HMANO)·H₂MANO·CH₃CN were studied by X-ray diffractometry. The copper atom is in an elongated, tetragonally distorted octahedral environment in 1 and 2 and in 3a has a coordination polyhedron intermediate between a square pyramid and a trigonal bipyramid, as evaluated in terms of the parameter τ. In 1 and 2 the α-hydroxycarboxylato ligand is bidentate and monoanionic but in 3a there are three forms: a monodentate monoanion, a monoanionic counterion, and a neutral molecule.     

Molybdenum(VI) network polymers based on anion–π interaction and hydrogen bonding: Synthesis, crystal structures and oxidation catalytic application

A crystallographic investigation of anion–π interactions and hydrogen bonds on the preferred structural motifs of molybdenum(VI) complexes has been carried out. Two molybdenum(VI) network polymers MoO₂F₄·(Hinca)₂ (1) and MoO₂F₃(H₂O)·(Hinpa) (2), where inca = isonicotinamide and inpa = isonipecotamide, have been synthesized, crystallographically characterized and successfully applied to alcohol oxidation reaction. Complex 1 crystallizes in the monoclinic space C2/c: a = 16.832(3) Å, b = 8.8189(15) Å, c = 12.568(2) Å, β = 118.929(3)°, V = 1560.1(5) Å³, Z = 4. Complex 2 crystallizes in the triclinic space P-1: a = 5.459(2) Å, b = 9.189(4) Å, c = 12.204(5) Å, α = 71.341(6)°, β = 81.712(7)°, γ = 77.705(7)°, V = 564.8(4) Å³, Z = 2. Complex 1 consists of hydrogen bonding and anion–π interactions, both of which are considered as important factors for controlling the geometric features and packing characteristics of the crystal structure. The geometry of the sandwich complex of [MoO₂F₄]²⁻ with two pyridine rings indicates that the anion–π interaction is an additive and provides a base for the design and synthesis of new complexes. For complex 2, the anions and the protonated inpa ligands form a 2D supramolecular network by four different types of hydrogen contacts (N–HF, N–HO, O–HF and O–HO). The catalytic ability of complexes 1 and 2 has also been evaluated by applying them to the oxidation of benzyl alcohol with TBHP as oxidant.     

A Hydrogen Adipato‐bridged Copper(II) Coordination Polymer: [Cu(bpy)(HL)]2L · 6H2O (bpy = 2, 2'‐Bipyridine,H2L = Adipic Acid)

Reaction of a fresh Cu(OH)_2x(CO₃)_1—x · yH₂O precipitate with adipic acid (H₂L) and 2, 2'—bipyridine (bpy) in ethanolic aqueous solution at room temperature afforded the hydrogen adipato bridged Cu^II coordination polymer [Cu(bpy)(HL)]₂L · 6H₂O consisting of double chains according to {[Cu(bpy)(HL)_2/2]₂L} and hydrogen bonded H₂O molecules. The chains result from [Cu(bpy)]²⁺ units bridged by bis—monodentate hydrogen adipato ligands and further crosslinked by bis—monodentate adipato ligands. Through the interchain π—π stacking interactions and interchain C(bpy)—H···O(adipato) hydrogen bonding interactions, the double chains are assembled into layers, between which the crystal H₂O molecules are located. The Cu atoms are square pyramidally coordinated by two N atoms of one bpy ligand and three O atoms of one adipato ligand and two hydrogen adipato ligands. The doubly bonded oxygen atom of the protonated carboxyl group occupies the apical position (Cu—N: 1.997, 2.005 Å; equatorial Cu—O: 1.925, 1.942 Å; apical Cu—O: 2.354 Å). Furthermore, the thermal behavior of the compound will be discussed. Crystal data: triclinic, P1¯ (no. 2), a = 9.618(1) Å, b = 9.933(1) Å, c = 12.782(2) Å, α = 70.88(1)°, β = 73.70(1)°, γ = 75.60(1)°, V = 1090.7(2) ų, Z = 1, R = 0.0453 and wR² = 0.1265 for 4643 observed reflections (F_o² > 2σ(F_o²)) out of 4985 unique reflections.     

Synthesis, structures and photophysics of novel luminescent platinum–copper complexes

The novel hexanuclear platinum–copper complex [Pt₂Cu₄(C₆F₅)₄(CC^tBu)₄(acetone)₂] (1) and the polynuclear derivative [PtCu₂(C₆F₅)₂(CCPh)₂]_x (2), which crystallises in acetone as [Pt₂Cu₄(C₆F₅)₄(CCPh)₄(acetone)₄] (2)·(acetone)₄, have been prepared using [cis-Pt(C₆F₅)₂(THF)₂] and the corresponding copper–acetylide [Cu(CCR)]_x (molar ratio 1:2) as starting materials. Treatment of 1 and 2 with 2,2′-bipyridine (molar ratio Cu–bipy 1:1), afforded the new trinuclear derivatives [{cis-Pt(C₆F₅)₂(μ-CCR)₂}{Cu(bipy)}₂] (R=^tBu 3, Ph 4), in which the dianionic 3-platina-1,4-diyne acts as a didentate bridging ligand to two different cationic Cu(bipy) units through η²-side-on coordination of the alkynyl fragments. While similar treatment of 1 with dppe (Cu–dppe 1:1) yielded [{cis-Pt(C₆F₅)₂(μ-CC^tBu)₂}{Cu(dppe)}₂] (5), the analogous reaction of 2 with dppe afforded a mixture of complexes containing [Pt(C₆F₅)(CCPh)(dppe)] as the main platinum compound. The crystal structures of 1, 2·(acetone)₄, 3 and 4 and the luminescent behaviour of all complexes have been determined. A comparison of the photoluminescent spectra of 1 and 2 with those of the related platinum–silver species [PtAg₂(C₆F₅)₂(CCR)₂]_x and the monomeric [cis-Pt(C₆F₅)₂(CCR)₂]²⁻ suggests the presence of emitting states bearing a large cluster [PtM₂]_x-to-ligand (alkynide) charge transfer (CLCT).     

The synthesis, structure and reactivity of aldehyde substituted η-allylic complexes of molybdenum

Reaction of cis-[Mo(NCMe)₂(CO)₂(η⁵-L)][BF₄] (L=C₅H₅ or C₅Me₅) with 1-acetoxybuta-1,3-diene gives the cationic complexes [Mo{η⁴-syn-s-cis-CH₂CHCHCH(OAc)}(CO)₂(η⁵-L)][BF₄], which, on reaction with aqueous NaHCO₃/CH₂Cl₂, afford good yields of the anti-aldehyde substituted complexes [Mo{η³-exo-anti-CH₂CHCH(CHO)}(CO)₂(η⁵-L)] 2 (L=C₅Me₅), 4 (L=C₅H₅)]. The corresponding η⁵-indenyl substituted complex 5 was prepared by protonation (HBF₄·OEt₂) of [Mo(η³-C₃H₅)(CO)₂(η⁵-C₉H₇)] followed by addition of CH₂=CHCH=CH(OAc) and hydrolysis (aq. NaHCO₃/CH₂Cl₂). An X-ray crystallographic study of complex 2 confirmed the structure and showed that there is a contribution from a zwitterionic form involving donation of electron density from the molybdenum to the aldehyde carbonyl group. Treatment of 2 and 4, in methanol solution, with NaBH₄ afforded the alcohols [Mo{η³-exo-anti-CH₂CHCHCH₂(OH)}(CO)₂(η⁵-L)] [6 (L=C₅H₅), 8 (L=C₅Me₅)]; however, prolonged (30 h) reaction with NaBH₄/MeOH surprisingly gave good yields of the methoxy-substituted complexes [Mo{η³-exo-anti-CH₂CHCHCH₂(OMe)}(CO)₂(η⁵-L)] [7 (L=C₅H₅), 9 (L=C₅Me₅)], the structure of 7 being confirmed by single crystal X-ray crystallography. This methoxylation reaction can be explained by coordination of the hydroxyl group present in 6 and 8 onto B₂H₆ to form the potential leaving group HOBH₃⁻, which on ionisation affords [Mo(η⁴-exo-buta-1-3-diene)(CO)₂(η⁵-L)]⁺ which is captured by reaction with OMe⁻. Complex 8 is also formed in good yield on reaction of 2 with HBF₄·OEt₂ followed by treatment of the resulting cation [Mo{η⁴-exo-s-cis-syn-CH₂CHCHCH(OH)}(CO)₂(η⁵-C₅Me₅)][BF₄] with Na[BH₃CN]. Reaction of 4 with the Grignard reagents MeMgI, EtMgBr or PhMgCl afforded moderate yields of the alcohols [Mo{η³-exo-anti-CH₂CHCHCH(OH)R}(CO)₂(η⁵-C₅H₅)] [11 (R=Me), 12 (R=Et), 13 (R=Ph)]. Similarly, treatment of 2 with MeLi gave the corresponding alcohol 14. An attempt to carry out the Oppenauer oxidation [Al(OPr′)₃/Me₂CO] of 11 resulted in an elimination reaction and the formation of the η³-s-pentadienyl complex [Mo{η³-exo-anti-CH₂CHCH(CHCH₂)}(CO)₂(η⁵-C₅H₅)], which was structurally identified by X-ray crystallography. Interestingly, oxidation of 6 with [Bu₄ⁿN][RuO₄]/morpholine-N-oxide affords the aldehyde complex, 4 in good yield. Finally, reaction of 11 with [NO][BF₄] followed by addition of Na₂CO₃ affords the fur-3-ene complex [Mo{η²-

(H)Me}(CO)(NO)(η⁵-C₅H₅)].     

Hydroxo‐bridged Tetranuclear CuII Complexes: {[Cu(bpy)(OH)]4Cl2}Cl2 · 6 H2O and {[Cu(phen)(OH)]4(H2O)2}]Cl4 · 4 H2O

The blue tetranuclear Cu^II complexes {[Cu(bpy)(OH)]₄Cl₂}Cl₂ · 6 H₂O ( 1 ) and {[Cu(phen)(OH)]₄(H₂O)₂}Cl₄ · 4 H₂O ( 2 ) were synthesized and characterized by single crystal X‐ray diffraction. ( 1 ): P 1 (no. 2), a = 9.240(1) Å, b = 10.366(2) Å, c = 12.973(2) Å, α = 85.76(1)°, β = 75.94(1)°, γ = 72.94(1)°, V = 1152.2(4) ų, Z = 1; ( 2 ): P 1 (no. 2), a = 9.770(3) Å, b = 10.118(3) Å, c = 14.258(4) Å, α = 83.72(2)°, β = 70.31(1)°, γ = 70.63(1)°, V = 1252.0(9) ų, Z = 1. The building units are centrosymmetric tetranuclear {[Cu(bpy)(OH)]₄Cl₂}²⁺ and {[Cu(phen)(OH)]₄(H₂O)₂}⁴⁺ complex cations formed by condensation of four elongated square pyramids CuN₂(OH)₂L^ap with the apical ligands L^ap = Cl, H₂O, OH. The resulting [Cu₄(μ₂‐OH)₂(μ₃‐OH)₂] core has the shape of a zigzag band of three Cu₂(OH)₂ squares. The cations exhibit intramolecular and intermolecular π‐π stacking interactions and the latter form 2D layers with the non‐bonded Cl^– anions and H₂O molecules in between (bond lengths: Cu–N = 1.995–2.038 Å; Cu–O = 1.927–1.982 Å; Cu–Cl^ap = 2.563; Cu–O^ap(OH) = 2.334–2.369 Å; Cu–O^ap(H₂O) = 2.256 Å). The Cu…Cu distances of about 2.93 Å do not indicate direct interactions, but the strongly reduced magnetic moment of about 2.74 B.M. corresponds with only two unpaired electrons per formula unit of 1 (1.37 B.M./Cu) and obviously results from intramolecular spin couplings (χ_m(T‐θ) = 0.933 cm³ · mol^–1 · K with θ = –0.7 K).     

An Azelaato‐bridged Dinuclear Copper(II) Complex, [Cu2(phen)2(C9H14O4)2] · 6 H2O (phen = 1,10‐phenanthroline)

The title compound [Cu₂(phen)₂(C₉H₁₄O₄)₂] · 6 H₂O was prepared by the reaction of CuCl₂ · 2 H₂O, 1,10‐phenanthroline (phen), azelaic acid and Na₂CO₃ in a CH₃OH/H₂O solution. The crystal structure (monoclinic, C2/c (no. 15), a = 22.346(3), b = 11.862(1), c = 17.989(3) Å, β = 91.71(1)°, Z = 4, R = 0.0473, wR² = 0.1344 for 4279 observed reflections) consists of centrosymmetric dinuclear [Cu₂(phen)₂(C₉H₁₄O₄)₂] complexes and hydrogen bonded H₂O molecules. The Cu atom is square‐planar coordinated by the two N atoms of the chelating phen ligand and two O atoms of different bidentate bridging azelaate groups with d(Cu–N) = 2.053, 2.122(2) Å and d(Cu–O) = 1.948(2), 2.031(2) Å. Two azelaate anions bridge two common Cu atoms via the terminal O atoms (d(C–O) = 1.29(2) Å; d(C–C) = 1.550(4)–1.583(4) Å). Phen ligands of adjacent complexes cover each other at distances of about 3.62 Å, indicating π‐π stacking interaction, by which the complexes are linked to 1 D bands.     

Three copper(II) complexes of thiophene-2,5-dicarboxylic acid with dissimilar ligands: Synthesis, IR and UV–Vis spectra, thermal properties and structural characterizations

Three thiophene-2,5-dicarboxylic acid (H₂tdc) complexes of copper(II) with 2-aminomethylpyridine (ampy), {[Cu₂(μ-tdc)₂(ampy)₂]·2DMF}_n (1), ethylenediamine (en), trans-[Cu(H₂O)₂(en)₂](tdc) (2) and 4-methylimidazole (4-meim), trans-[Cu(H₂O)₂(4-meim)₄](tdc)·4H₂O (3) have been synthesized and characterized by spectral (IR, UV–Vis), thermal analyses and X-ray diffraction techniques. In 1, thiophene-2,5-dicarboxylate acts as a bridging bis(bidentate) ligand through four carboxylate oxygen atoms forming a 1-D zigzag polymeric chain, whereas in 2 and 3 the tdc dianion behaves as a counter ion. In all cases, the Cu(II) centers have an octahedral coordination geometry. Three-dimensional frameworks are constructed though hydrogen bonding and/or C–H···π interactions in the three complexes.     

Organic carboxylate anions effect on the structures of a series of Mn(II) complexes based on 2-phenylimidazo[4,5-f]1,10-phenanthroline ligand

In our efforts to tune the structures of Mn(II) complexes by selection of organic carboxylic acid ligands, six new complexes [Mn(PIP)₂Cl₂] (1), [Mn(PIP)₂(4,4′-bpdc)(H₂O)]·2H₂O (2), [Mn(PIP)₂(1,4-bdc)] (3), [Mn(PIP)(1,3-bdc)] (4), [Mn(PIP)₂(2,6-napdc)]·H₂O (5), and [Mn(PIP)(1,4-napdc)]·H₂O (6) were obtained, where PIP=2-phenylimidazo[4,5-f]1,10-phenanthroline, 4,4′-H₂bpdc=biphenyl-4,4′-dicarboxylic acid, 1,4-H₂bdc=benzene-1,4-dicarboxylic acid, 1,3-H₂bdc=benzene-1,3-dicarboxylic acid, 2,6-H₂napdc=2,6-naphthalenedicarboxylic acid, 1,4-H₂napdc=1,4-naphthalenedicarboxylic acid. All complexes have been structurally characterized by IR, elemental analyses, and single crystal X-ray diffraction. Structural analyses show that complexes 1 and 2 possess mononuclear structures, complexes 3, 4, and 5 feature chain structures, and complex 6 exhibits a 2D (4,4) network. The structural difference of 1–6 indicates that organic carboxylate anions play important roles in the formation of such coordination architectures. Furthermore, the thermal properties of complexes 1–6 and the magnetic property of 4 have been investigated.     

Two Novel CuII Phenanthroline Adipato Complexes with π‐π Stacking Interactions: [Cu(phen)2(C6H8O4)] · 4.5 H2O and [(Cu2(phen)2Cl2)(C6H8O4)] · 4 H2O

The blue copper complex compounds [Cu(phen)₂(C₆H₈O₄)] · 4.5 H₂O ( 1 ) and [(Cu₂(phen)₂Cl₂)(C₆H₈O₄)] · 4 H₂O ( 2 ) were synthesized from CuCl₂, 1,10‐phenanthroline (phen) and adipic acid in CH₃OH/H₂O solutions. [Cu(phen)₂‐ (C₆H₈O₄)] complexes and hydrogen bonded H₂O molecules form the crystal structure of ( 1 ) (P1 (no. 2), a = 10.086(2) Å, b = 11.470(2) Å, c = 16.523(3) Å, α = 99.80(1)°, β = 115.13(1)°, γ = 115.13(1)°, V = 1617.5(5) ų, Z = 2). The Cu atoms are square‐pyramidally coordinated by four N atoms of the phen ligands and one O atom of the adipate anion (d(Cu–O) = 1.989 Å, d(Cu–N) = 2.032–2.040 Å, axial d(Cu–N) = 2.235 Å). π‐π stacking interactions between phen ligands are responsible for the formation of supramolecular assemblies of [Cu(phen)₂(C₆H₈O₄)] complex molecules into 1 D chains along [111]. The crystal structure of ( 2 ) shows polymeric [(Cu₂(phen)₂Cl₂)(C₆H₈O₄)_2/2] chains (P1 (no. 2), a = 7.013(1) Å, b = 10.376(1) Å, c = 11.372(3) Å, α = 73.64(1)°, β = 78.15(2)°, γ = 81.44(1)°, V = 773.5(2) ų, Z = 1). The Cu atoms are fivefold coordinated by two Cl atoms, two N atoms of phen ligands and one O atom of the adipate anion, forming [CuCl₂N₂O] square pyramids with an axial Cl atom (d(Cu–O) = 1.958 Å, d(Cu–N) = 2.017–2.033 Å, d(Cu–Cl) = 2.281 Å; axial d(Cu–Cl) = 2.724 Å). Two square pyramids are condensed via the common Cl–Cl edge to centrosymmetric [Cu₂Cl₂N₄O₂] dimers, which are connected via the adipate anions to form the [(Cu₂(phen)₂Cl₂)(C₆H₈O₄)_2/2] chains. The supramolecular 3 D network results from π‐π stacking interactions between the chains. H₂O molecules are located in tunnels.