Solid-state coordination chemistry of the Cu/triazolate/X system (X = F-, Cl-, Br-, I-, OH-, and SO4(2-))

Hydrothermal reactions of 1,2,4-triazole with the appropriate copper salt have provided eight structurally unique members of the Cu/triazolate/X system, with X = F-, Cl-, Br-, I-, OH-, and SO4(2-). The anionic components X of [Cu3(trz)4(H2O)3]F2 (1) and [Cu6(trz)4Br]Cu4Br4(OH) (4) do not participate in the framework connectivity, acting as isolated charge-compensating counterions. In contrast, the anionic subunits X of [Cu(II)Cu(I)(trz)Cl2] (2), [Cu6(trz)4Br2] (3), [Cu(II)Cu(I)(trz)Br2] (5), [Cu3(trz)I2] (6), [Cu6(II)Cu2(I)(trz)6(SO4)3(OH)2(H2O)] (8), and [Cu4(trz)3]OH.7.5H2O (9.7.5H2O) are intimately involved in the three-dimensional connectivities. The structure of [Cu(II)Cu(I)(trz)2][Cu3(I)I4] (7) is constructed from two independent substructures: a three-dimensional cationic {Cu2(trz)2}n(n+) component and {Cu3I4}n(n-) chains. Curiously, four of the structures are mixed-valence Cu(I)/Cu(II) materials: 2, 5, 7, and 8. The only Cu(II) species is 1, while 3, 4, 6, and 9.7.5H2O exhibit exclusively Cu(I) sites. The magnetic properties of the Cu(II) species 1 and of the mixed-valence materials 5, 7, 8, and the previously reported [Cu3(trz)3OH][Cu2Br4] have been studied. The temperature-dependent magnetic susceptibility of 1 conforms to a simple isotropic model above 13 K, while below this temperature, there is weak ferromagnetic ordering due to spin canting of the antiferromagnetically coupled trimer units. Compounds 5 and 7 exhibit magnetic properties consistent with a one-dimensional chain model. The magnetic data for 8 were fit over the temperature range 2-300 K using the molecular field approximation with J = 204 cm(-1), g = 2.25, and zJ' = -38 cm(-1). The magnetic properties of [Cu3(trz)3OH][Cu2Br4] are similar to those of 8, as anticipated from the presence of similar triangular {Cu3(trz)3(mu3-OH)}(2+) building blocks. The Cu(I) species 3, 4, 6, and 9 as well as the previously reported [Cu(5)(trz)3Cl2] exhibit luminescence thermochromism. The spectra are characterized by broad emissions, long lifetimes, and significant Stokes' shifts, characteristic of phosphorescence.     

Synthesis and Crystal Structure of Dinuclear Copper Cluster Compound ［Cu（dtp）PPh_3］_2

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Self-assembly of polyoxometalate-based metal organic frameworks based on octamolybdates and copper-organic units: from Cu(II), Cu(I,II) to Cu(I) via changing organic amine

Six polyoxometalate (POM)-based hybrid materials have been designed and synthesized based on octamolybdate building blocks and copper-organic units at different pH values under hydrothermal conditions, namely, [H2bbi][Cu(II)(bbi)2(beta-Mo8O26)] (1), [Cu(II)(bbi)2(H2O)(beta-Mo8O26)0.5] (2), [Cu(II)(bbi)2(alpha-Mo8O26)][Cu(I)(bbi)]2 (3), [Cu(II)Cu(I)(bbi)3(alpha-Mo8O26)][Cu(I)(bbi)] (4), [Cu(I)(bbi)]2[Cu(I)2(bbi)2(delta-Mo8O26)0.5][alpha-Mo8O26]0.5 (5), and [Cu(I)(bbi)][Cu(I)(bbi)(theta-Mo8O26)0.5] (6), where bbi is 1,1'-(1,4-butanediyl)bis(imidazole). Their crystal structures have been determined by X-ray diffraction. In compound 1, the bbi ligands with bis-monodentate coordination modes link Cu(II) cations to generate a 2D copper-organic unit with (4, 4) net, which is pillared by the (beta-Mo8O26)(4-) anions to form a 3D framework with alpha-Po topology. The similar copper-organic units are connected alternately by (beta-Mo8O26)(4-) anions to generate a 3D 2-fold interpenetrating (4,6)-connected framework with (4(4) x 6(2))(4(4) x 6(10) x 8) topology in compound 2. Compounds 3 and 4 are supramolecular isomers with polythreaded topology. If Cu (I)...O interactions are considered, the structure of 3 is a novel self-penetrating (3,4,6)-connected framework with (5(2) x 8)2(5(4) x 6 x 8)(4(4) x 6(10) x 10) topology, and the structure of 4 is a (4,6)-connected framework with (4(2) x 6(3) x 7)(5.6(4) x 8)(4(2) x 5(6) x 6(6) x 8)(4(2) x 5(6) x 6(4) x 7 x 8(2)) topology. Different from compounds 3 and 4, compounds 5 and 6 are supramolecular isomers with polythreaded topology based on different octamolybdate isomers. By careful inspection of the structures of 1-6, it is believed that various copper-organic units, which are formed by bbi ligands combined with Cu(II)/Cu(I) cations, octamolybdates with different types and coordination modes, and the nonbonding interactions between polyanions and copper-organic units are important for the formation of the different structures. In addition, with step by step increasing of the amount of organic amine, we have achieved the transformation of Cu(II) ions into Cu(I) ones in different degrees in POMs-based metal-organic frameworks (MOFs) for the first time. The infrared spectra, X-ray powder diffraction, and thermogravimetric analyses have been investigated in detail for all compounds, and the luminescent properties have been also been investigated for compounds 3 and 4.     

Synthesis and characterization of [Cu(NHC)2]X complexes: catalytic and mechanistic studies of hydrosilylation reactions

The preparation of two series of [Cu(NHC)2]X complexes (NHC=N-heterocyclic carbene, X=PF6 or BF4) in high yields from readily available materials is reported. These complexes have been spectroscopically and structurally characterized. The activity of these cationic bis-NHC complexes in the hydrosilylation of ketones was examined, and both the ligand and the counterion showed a significant influence on the catalytic performance. Moreover, when compared with related [Cu(NHC)]-based systems, these cationic complexes proved to be more efficient under similar reaction conditions. The activation step of [Cu(NHC)2]X precatalysts towards hydrosilylation was investigated by means of 1H NMR spectroscopy. Notably, it was shown that one of the N,N'-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) ligands in [Cu(IPr)2]BF4 is displaced by tBuO(-) in the presence of NaOtBu, producing the neutral [Cu(IPr)(OtBu)]. This copper alkoxide is known to be a direct precursor of an NHC-copper hydride, the actual active species in this transformation. Furthermore, reagent loading and counterion effects have been rationalized in light of the species formed during the reaction.     

Oxo- and imidovanadium complexes incorporating methylene- and dimethyleneoxa-bridged calix[3]- and -[4]arenes: synthesis, structures and ethylene polymerisation catalysis

Reaction of [V(X)(OR)3] (X=O, Np-tolyl; R=Et, nPr or tBu) with p-tert-butylhexahomotrioxacalix[3]areneH3, LH3, affords the air-stable complexes [{V(X)L}n] (X=O, n=1 (1); X=Np-tolyl, n=2 (2)). Alternatively, 1 is readily available either from interaction of [V(mes)3THF] with LH3, and subsequent oxidation with O2 or upon reaction of LLi3 with [VOCl3]. Reaction of [V(Np-tolyl)(OtBu)3] with 1,3-dimethylether-p-tert-butylcalix[4]areneH2, Cax(OMe)2(OH)2, afforded [{VO(OtBu)}2(mu-O)Cax(OMe)2(O)2].2 MeCN (42 MeCN), in which two vanadium atoms are bound to just one calix[4]arene ligand; the n-propoxide analogue of 4, namely [{VO(OnPr)}2(mu-O)Cax(OMe)2(O)2].1.5 MeCN (51.5 MeCN), has also been isolated from a similar reaction using [V(O)(OnPr)3]. Reaction of [VOCl3], LiOtBu, (Me3Si)2O and Cax(OMe)2(OH)2 gave [{VO(OtBu)Cax(OMe)2(O)2}2Li4O2].8 MeCN (68 MeCN), in which an Li4O4 cube (two of the oxygen atoms are derived from the calixarene ligands) is sandwiched between two Cax(OMe)2(O)2. The reaction between [V(Np-tolyl)(OtBu)3] and Cax(OMe)2(OH)2, afforded [V(Np-tolyl)(OtBu)2Cax(OMe)2(O)(OH)]5 MeCN (75 MeCN), in which two tert-butoxide groups remain bound to the tetrahedral vanadium atom, which itself is bound to the calix[4]arene through only one phenolic oxygen atom. Reaction of p-tert-butylcalix[4]areneH4, Cax(OH)4 and [V(Np-tolyl)(OnPr)3] led to loss of the imido group and formation of the dimeric complex [{VCax(O)4(NCMe)}2].6 MeCN (86 MeCN). Monomeric vanadyl oxo- and imidocalix[4]arene complexes [V(X)Cax(O)3(OMe)(NCMe)] (X=O (11), Np-tolyl (12)) were obtained by the reaction of the methylether-p-tert-butylcalix[4]areneH3, Cax(OMe)(OH)3, and [V(X)(OR)3] (R=Et or nPr). Vanadyl calix[4]arene fragments can be linked by the reaction of 2,6-bis(bromomethyl)pyridine with Cax(OH)4 and subsequent treatment with [VOCl3] to afford the complex [{VOCax(O)4}2(mu-2,6-(CH2)2C5H3N)].4 MeCN (134 MeCN). The compounds 1-13 have been structurally characterised by single-crystal X-ray diffraction. Upon activation with methylaluminoxane, these complexes displayed poor activities, however, the use of dimethylaluminium chloride and the reactivator ethyltrichloroacetate generates highly active, thermally stable catalysts for the conversion of ethylene to, at 25 degrees C, ultra-high-molecular-weight (>5, 500,000), linear polyethylene, whilst at higher temperature (80 degrees C), the molecular weight of the polyethylene drops to about 450,000. Using 1 and 2 at 25 degrees C for ethylene/propylene co-polymerisation (50:50 feed) leads to ultra-high-molecular-weight (>2,900,000) polymer with about 14.5 mol% propylene incorporation. The catalytic systems employing the methyleneoxa-bridged complexes 1 and 2 are an order of magnitude more active than the bimetallic complexes 5 and 13, which, in turn, are an order of magnitude more active than pro-catalysts 8, 11 and 12. These differences in activity are discussed in terms of the structures of each class of complex.     

Mo(W)/Cu/S cluster-based supramolecular arrays assembled from preformed clusters [Et4N]4[WS4Cu4I6] and [(n-Bu)4N]2[MoOS3Cu3X3] (X = I, SCN) with flexible ditopic ligands

In our working toward the rational design and synthesis of cluster-based supramolecular architectures, a set of new [WS4Cu4]- or [MoOS3Cu3]-based supramolecular assemblies have been prepared from reactions of preformed cluster compounds [Et4N]4[WS4Cu4I6] (1) and [(n-Bu)4N]2[MoOS3Cu3X3] (2, X = I; 3, X = SCN) with flexible ditopic ligands such as dipyridylsulfide (dps), dipyridyl disulfide (dpds), and their combinations with dicyanamide (dca) anion and 4,4'-bipy. The cluster precursor 1 reacted with dps or dpds and sodium dicyanamide (dca) in MeCN to produce [WS4Cu4I2(dps)3].2MeCN (4.2MeCN) and [WS4Cu4(dca)2(dpds)2].Et2O.2MeCN (5.Et2O.2MeCN), respectively. On the other hand, treatment of 2 with dpds in DMF/MeCN afforded [MoOS3Cu3I(dpds)2].0.5DMF.2(MeCN)0.5 (6.0.5DMF.2(MeCN)0.5) while reaction of 3 with sodium dicyanamide (dca) and 4,4'-bipy in DMF/MeCN gave rise to [MoOS3Cu3(dca)(4,4'-bipy)1.5].DMF.MeCN (7.DMF.MeCN). Compounds 4.2MeCN, 5.Et2O.2MeCN, 6.0.5DMF.2(MeCN)0.5, and 7.DMF.MeCN have been characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray crystallography. Compound 4 contains a 2D layer array made of the saddle-shaped [WS4Cu4] cores interlinked by three pairs of Cu-dps-Cu bridges. Compound 5 has another 2D layer structure in which the [WS4Cu4] cores are held together by four pairs of Cu-dca-Cu and Cu-dpds-Cu bridges. Compound 6 displays a 1D spiral chain structure built of the nido-like [MoOS3Cu3] cores via two pairs of Cu-dpds-Cu bridges. Compound 7 consists of a 2D staircase network in which each [MoOS3Cu3(4,4'-bipy]2 dimeric unit interconnects with four other equivalent units by a pair of 4,4'-bipy ligands and two pairs of dca anions. The [WS4Cu4] core in 4 or 5 and the [MoS3Cu3] core in 7 show a planar 4-connecting node and a seesaw-shaped 4-connecting node, respectively, which are unprecedented in cluster-based supramolecular compounds. The successful assembly of 4-7 from the three cluster precursors 1-3 through flexible ditopic ligands provides new routes to the rational design and construction of complicated cluster-based supramolecular arrays.     

Cu(I) beta-diketiminates for alkene aziridination: reversible Cu-arene binding and catalytic nitrene transfer from PhI=NTs

beta-Diketiminato Cu(I)-lutidine complexes [RMeNN]Cu(2,4-lutidine) (R = Me (4a), (i)Pr (4b)) were prepared in high yield from Tl[RMeNN] and [CuBr(2,4-lutidine)(2)](2). Both 4a and 4b reversibly dissociate lutidine base in toluene to give [RMeNN]Cu(toluene) solvento complexes. A related base-free dicopper species [[Me(2)NN]Cu](2) (6) bridged via eta(2)-binding of opposing N-aryl rings could be isolated by the addition of Tl[Me(2)NN] to CuBr. The lutidine precursors serve as precatalysts for the aziridination of alkenes with PhI=NTs. Styrene, beta-methylstyrene, and cyclooctene gave the highest yields (59-96%) with a low olefin to PhI=NTs ratio (3:1) and 5 mol % catalyst loading.     

Unsupported gold(I)-copper(I) interactions through eta1 Au-[Au(C6F5)2]- coordination to Cu+ Lewis acid sites

The reaction of the complex [Au2Ag2(C6F5)4)N[triple bond]CCH3)2]n (1) with 1 equiv of CuCl in the presence of 1 equiv of pyrimidine ligand leads to the formation of the heteronuclear Au(I)-Cu(I) organometallic polymer [Cu{Au(C6F5)2}(N[triple bond]CCH3)(mu2-C4H4N2)]n (2) through a transmetalation reaction. Complex 2 displays unprecedented unsupported Au(I)...Cu(I) interactions of [Au(C6F5)2]- units with the acid Cu(I) sites in a [Cu(N[triple bond]CCH3)(mu2-pyrimidine)]n+(n) polymeric chain. Complex 2 has a rich photophysics in solution and in the solid state.     

Surface organobarium and organomagnesium chemistry on periodic mesoporous silica MCM-41: convergent and sequential approaches traced by molecular models

The alkaline earth metal alkyl complexes [Ba(AlEt(4))(2)](n) and Mg(AlMe(4))(2) were directly grafted onto periodic mesoporous silica MCM-41, which had been dehydroxylated at 270 °C (specific surface area a(s): 1023 m(2) g(-1); pore volume V(p): 1.08 cm(3) g(-1); main pore diameter 3.4 nm). Alternatively, barium alkyl surface species were generated by sequential grafting of MCM-41 with Ba[N(SiHMe(2))(2)](2)(thf)(4) and AlEt(3) to yield the hybrid material AlEt(3)@Ba[N(SiHMe(2))(2)](2)(thf)(4)@MCM-41. For a better understanding of the surface chemistry, AlEt(3)@MCM-41 was also accessed. All hybrid materials were analyzed by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, elemental analysis, nitrogen physisorption, and solid-state NMR spectroscopy; this clearly revealed distinct surface chemistry for the alkylaluminate-treated materials [Ba(AlEt(4))(2)]@MCM-41 and Mg(AlMe(4))(2)@MCM-41. In an attempt to mimic the surface chemistry, the organometallic precursors were treated with HOSi(OtBu)(3). The reaction of equimolar amounts of {Ba[N(SiHMe(2))(2)](2)}(n) and HOSi(OtBu)(3) produced a mixed silylamido/siloxide cluster of Ba(3)[OSi(OtBu)(3)](3)[N(SiHMe(2))(2)](3) with bridging-only siloxide ligands as well as one bridging and two terminal silylamido ligands. The Schlenk equilibrium was found to govern the [Ba(AlEt(4))(2)](n)-HOSi(OtBu)(3) and Mg(AlMe(4))(2)-HOSi(OtBu)(3) reactions, leading to the isolation of complexes of [Ba(AlEt(4))(2) (toluene)](2) and Mg[OSi(OtBu)(3))](2)(AlMe(3))(2), respectively. Allowing for a donor-induced cleavage of Mg(AlMe(4))(2), the reaction of [MgMe(2)] with one or two equivalents of HOSi(OtBu)(3) was studied. While putative Mg[OSi(OtBu)(3)](Me) and Mg[OSi(OtBu)(3)](2) could not be crystallized from the reaction mixtures, cluster complexes Mg(5)(O)[OSi(OtBu)(3)](5)Me(3) and Mg(4)(OH)(2)[OSi(OtBu)(3)](6) could be unambiguously identified by X-ray crystallography.     

Solid State Synthesis and Structural Characterization of Binuclear Cu(I)-SbPh3 Complex [Cu(SbPh3)2I]2

Dimeric complex [Cu(SbPh3)2I]2 has been synthesized by a solid state reaction at a low heating temperature and its crystal structure has been analyzed by X-ray crystallography. The crystal is monoclinic, space group P21/a (#14), a = 20.436(5), b=14.125(3), c=24.683(3)(A), β=110.67(1)°, Z=4, V=6666(2)(A)3; C72H60Sb4I2Cu2, Mr = 1792, Dc = 1.787 g.cm-3, μ(MoKα) = 31.88 cm-1, F(000)=3440, R=0.038 and Rw=0.043 for 5632 observed reflections (I≥3.0σ(I)) and 361 refined parameters. The result reveals the copper and the bridging iodide atoms form an approximately planar rhomboid array. Effects of the bulkiness of the ligands upon the structures of the analogous complexes are discussed.     

Transient terminal Cu-nitrene intermediates from discrete dicopper nitrenes

Reaction of the copper(I) beta-diketiminate {[Me3NN]Cu}2(mu-toluene) with the aryl azide N3Ar (Ar = 3,5-Me2C6H3) in toluene results in immediate effervescence and formation of the dicopper nitrene {[Me3NN]Cu}2(mu-NAr) (2) in 77% yield. The X-ray structure of 2 shows nearly symmetric bonding of the nitrene to two Cu centers separated by 2.911(1) A with Cu-N distances of 1.794(5) and 1.808(5) A along with a Cu-N-Cu angle of 107.8(2) degrees . This structure is conceptually related to the dicopper carbenes {[MexNN]Cu}2(mu-CPh2) (x = 2 or 3) (Dai, X.; Warren J. Am. Chem. Soc. 2004, 126, 10085. Badiei, Y. M.; Warren J. Organomet. Chem. 2005, 690, 5989.) which exhibit shorter Cu-Cu distances (2.4635(7) or 2.485(1) A) and acute Cu-C-Cu angles (79.51(14) or 80.1(2) degrees ). Addition of the Cu(I) anilidoimine {[Me2AI]Cu}2 (prepared from CuOtBu and the aniline-imine H[Me2AI] in 77% yield) to a benzene-d6 solution of 2 results in the formation of two new anilidoimine complexes {[Me2AI]Cu(mu- NAr)Cu[Me3NN] (5) and {[Me2AI]Cu}2(mu-NAr) (6) as well as [Me3NN]Cu(benzene) over 3 h. These observations are consistent with the slow dissociation of a [Me3NN]Cu fragment from 2 to generate the transient terminal nitrenes [Me3NN]Cu=NAr and [Me2AI]Cu=NAr quickly trapped by the [Me2AI]Cu fragment to form the new unsymmetrical and symmetrical dicopper nitrenes 5 and 6. Preliminary reactivity studies indicate electrophilic reactivity at the nitrene moiety. Dicopper nitrene 2 reacts with 10 equiv PMe3 and CNtBu to give ArN=PMe3 and ArN=C=NtBu in 94% and 92% yields, respectively, with concomitant formation of [Me3NN]Cu(L) (L = PMe3 and CNtBu). Reaction between 2 and 2 equiv PMe3 allows for observation of the structurally characterized Cu(I) phosphaimide [Me3NN]Cu(ArN=PMe3) (7).     

Inorganic-organic hybrids formed by P,P'-diphenylmethylenediphosphinate, pcp2-, with the Cu2+ ion. X-ray crystal structures of [Cu(pcp)(H2O)2] x H2O and [Cu(pcp)(bipy)(H2O)

Weakly coordinated [Cu(pcp)(H2O)n] complexes are formed in aqueous solution, at room temperature, by interaction of P,P'-diphenylmethylene diphosphinic acid (H2pcp) with copper(II) ions. However, heating of the solutions gives rise to the formation of two extended metal-oxygen networks of formulas [Cu(pcp)(H2O)2] x H2O, 1, and [Cu(pcp)(H2O)2], 2. In the presence of 2,2'-bipyridyl (bipy) the diamine derivative [Cu(pcp)(bipy)(H2O)], 4, has been isolated. Complex 1 easily loses water to form a monohydrated derivative [Cu(pcp)H2O], 3, whereas 2 is completely dehydrated after prolonged heating at 150 degrees C, under vacuum. The compounds 1 and 2 have substantially different solid-state structures as shown by X-ray powder diffraction spectra, IR spectra, and thermogravimetric analyses. Consistently, the two complexes cannot be directly interconverted and present different dehydration pathways. Rehydration of these materials in both cases allows quantitative formation of 1. X-ray analysis established that the structure of 1 consists of a corrugated two-dimensional layered polymeric array, where infinite zigzag chains of Cu centers and bridging phenylphosphinate ligands are linked together through strong hydrogen-bonding interactions; the structure of 4 consists of monodimensional polymers, where the hydrogen-bonding interactions play an essential bridging role in the extended architecture. In both structures the metal center displays a five-coordinate environment with approximate square pyramidal geometry, with the pcp ligand acting as bidentate and monodentate in 1 and solely as bidentate in 4. In 1 the coordination sphere is completed through water molecules; in 4, through water and diamine ligands. The thermogravimetric analyses of the complexes are compared with those of the related hybrids [M(pcp)(H2O)3] x H2O, where M = Mn, Co, or Ni, confirming that noncoordinated water molecules also play a basic role in determining the molecular packing.     

Dinuclear Cu(I) complexes of 1,2,4,5-tetra(7-azaindolyl)benzene: persistent 3-coordinate geometry, luminescence, and reactivity

Five Cu(I) complexes [Cu2(ttab)(CH3CN)2][BF4]2 (1), [Cu(2)(ttab)(PPh3)2][BF4]2 (2), [Cu2(ttab)I2] (3), [Cu2(ttab)(I3)2] (4), and [Cu2(ttab)(I)BF4]n (5) with 1,2,4,5-tetra(7-azaindolyl)benzene (ttab) have been synthesized and characterized. The structures of compound 1, 2, 4, and 5 have been determined by single-crystal X-ray diffraction analyses, which established that 1, 2, and 4 are discrete dinuclear Cu2 compounds while compound 5 is a 1D coordination polymer with the I- ligand bridging two dinuclear Cu2 units. The ttab ligand in all four complexes adopts a 1,3-chelation mode. The Cu(I) center in all complexes is three-coordinate. Close contact between the Cu(I) center and the benzene ring in the ttab ligand was observed in all four structures, which is believed to play a role in stabilizing the three-coordinate geometry of the Cu(I) center. The crystals of 1, 2, and 5 contain channels in the lattice that host solvent molecules such as CH2Cl2 and toluene. Fluorescent measurements established that, in solution, compounds 1-3 display weak blue luminescence which originates from the ttab but is significantly red-shifted and has a much lower emission intensity, compared to the free ttab ligand. The application of compound 1 in C-N cross-coupling reactions was examined by using the reaction of phenyl halides with imidazole as a model system. For the reaction with phenyl iodide, 1 was found to be as effective a catalyst as the CuI/1,10-phenanthroline system. For the reaction with phenyl bromide, 1 is less effective than the CuI/1,10-phenanthroline system. Compound 1 reacts with O2 gas, as established by UV-vis spectra, but the oxidized products have not been characterized.     

Aggregation of [Cu(II)4] building blocks into [Cu(II)8] clusters or a [Cu(II)4]infinity chain through subtle chemical control

Coordination complexes of the ligand H3L [1,3-bis(3-oxo-3-phenylpropionyl)-2-hydroxy-5-methylbenzene] with Cu(II) are reported. Clusters showing various nuclearities or modes of supramolecular organization have been prepared by slightly changing the reaction conditions and have been crystallographically characterized. The reaction of H3L with one equivalent of Cu(OAc)2 in DMF yields the dinuclear complex [Cu2(HL)2(dmf)2] (1). Reaction in MeOH of H3L with an increased amount of metal, in the form of Cu(NO3)2, and excess strong base (nBu4NOH) affords the cluster [Cu8(L)2(OMe)8(NO3)2] (2). Complex 2 is a dimer of two linear [Cu4] arrays bridged by methoxide ligands, where the polynucleating ligand is fully deprotonated. The [Cu4]2 clusters are linked to each other by NO3- bridges to form one-dimensional coordination polymers. The link between [Cu8] units and their relative spatial positioning can be modified by changing the anion of the Cu(II) salt, as demonstrated by the synthesis of the cluster polymers [Cu8(L)2(OMe)8Cl2] (3) and [Cu8(L)(OMe)7.86Br2.14] (4), where only NO3- has been replaced by Cl- or Br-, respectively. Similarly, when ClO4- is used, compound [Cu8(L)2(OMe)8(ClO4)2(MeOH)4] (5) can be isolated. It contains independent [Cu8] units. A slight change in the stoichiometry of the reaction leading to 2 affords the related complex catena-[Cu4(L)(OMe)3(NO3)2(H2O)0.36] (6). This polymer contains essentially the same [Cu4] moiety as 2, albeit organized in a completely different arrangement. Each [Cu4] unit in 6 is linked by OMe- ligands to two such equivalent groups to form an infinite chain. Magnetic susceptibility measurements reveal weak antiferromagnetic exchange between Cu(II) centers in 1 (J = -0.73 cm(-1)) and strong antiferromagnetic coupling within [Cu4] chains in 2, 5, and 6 (most negative J values of -113.8 and -177.3 cm(-1) for 2 and 6, respectively).     

Construction of new heteroselenometallic clusters: formation of crownlike [Et4N]4[(mu5-WSe4)(CuI)5(mu-I)2] and octahedral polymeric [(mu6-WSe4)Cu6I4(py)4]n from planar [Et4N]4[(mu4-WSe4)Cu4I6] with additional faces

The coplanar cluster compound [Et4N]4[(mu4-WSe4)Cu4I6] (1) was prepared from reaction of [Et4N]2[WSe4] with 4 equiv of CuI in N,N-dimethylformamide (DMF) solution in the presence of [Et(4)N]I. Treatment of 1 with pyridine (py) in dry MeCN gave the neutral cluster [(mu4-WSe4)Cu4(py)6I2] (2) in good yield. Recrystallization of 1 from py/i-PrOH resulted in the reorganization of the coplanar WSe4Cu4 core and the formation of a neutral polymeric cluster [(mu3-WOSe3)Cu3(py)3(mu-I)]n (3) containing a nest-shaped OWSe3Cu3 core and a terminal W=O bond. The interaction of cluster 1 with excess PPh3 in CH3Cl3 gave [(mu3-WSe4)Cu3(PPh3)3(mu3-I)] (4) which has a cubanelike SeWSe3Cu3I core. Treatment of 1 with 1 equiv of CuI in dimethyl sulfoxide (DMSO) yielded [Et4N]4[(mu5-WSe4)(CuI)5(mu-I)2] (5) which has a crown-like core structure. Treatment of 1 in DMF with 2 equiv of CuI in the presence of py resulted in the formation of a two-dimensional polymeric cluster, [(mu6-WSe4)Cu6I4(py)4]n (6), consisting of an octahedral WSe4Cu6 repeating unit. The solid-state structures of clusters 3, 5, and 6 have been further established by X-ray crystallography. The nonlinear optical properties of 6 have been also investigated. Cluster 6 was found to exhibit good photostability and a large optical limiting effect with the limiting threshold being ca. 0.3 J cm(-2).     

Phosphorescent Cu(I) complexes of 2-(2'-pyridylbenzimidazolyl)benzene: impact of phosphine ancillary ligands on electronic and photophysical properties of the Cu(I) complexes

Four mononuclear Cu(I) complexes of 2-(2'-pyridyl)benzimidazolylbenzene (pbb) with four different ancillary phosphine ligands PPh(3), bis[2-(diphenylphosphino)phenyl]ether (DPEphos), bis(diphenylphosphino)ethane (dppe), and bis(diphenylphosphinomethyl)diphenylborate (DPPMB) have been synthesized. The crystal structures of [Cu(pbb)(PPh(3))(2)][BF(4)] (1), [Cu(pbb)(dppe)][BF(4)] (2), [Cu(pbb)(DPEphos)][BF(4)] (3), and the neutral complex [Cu(pbb)(DPPMB)] (4) were determined by single-crystal X-ray diffraction analyses. The impact of the phosphine ligands on the structures of the copper(I) complexes was examined, revealing that the most significant impact of the phosphine ligands is on the P-Cu-P bond angle. The electronic and photophysical properties of the new complexes were examined by using UV-vis, fluorescence, and phosphorescence spectroscopies and electrochemical analysis. All four complexes display a weak MLCT absorption band that varies considerably with the phosphine ligand. At ambient temperature, no emission was observed for any of the complexes in solution. However, when doped into PMMA polymer (20 wt %), at ambient temperature, all four complexes emit light with a color ranging from green to red-orange, depending on the phosphine ligand. The emission of the new copper complexes has an exceptionally long decay lifetime (>200 micros). Ab initio MO calculations established that the lowest electronic transition in the copper(I) complexes is MLCT in nature. The electronic and photophysical properties of the new mononuclear Cu(I) complexes were compared with those of the corresponding polynuclear Cu(I) complexes based on the 2-(2'-dipyridyl)benzimidazolyl derivative ligands and the previously extensively studied phenanthroline-based Cu(I) complexes.     

First example of a 2:1 cocrystal of mixed Cu(I)/Cu(II) complexes and a novel ferromagnetic bis(mu-hydroxo)dicopper(II) complex with a bis(pyrazol-1-yl)methane bidentate ligand

A unique 2:1 cocrystal of mixed Cu(I)/Cu(II) complexes [Cu(I)(H2CPz2)(MeCN)2](ClO4) (1) and [Cu(II)(H2CPz2)2(ClO4)2] (4), a novel ferromagnetic ClO(4-)-bridged bis(mu-hydroxo)dicopper(II) complex, [Cu2(H2CPz2)2(OH)2(ClO4)](ClO4)(CH3CN)(0.5) (5), and a bischelated copper(I) complex, [Cu(H2CPz2)2](ClO4) (2), prepared from a one-pot reaction of [Cu(MeCN)4](ClO4) and H2CPz2, are described. The structures of these complexes have been determined by X-ray crystallographic methods. The Cu(I)-N(acetonitrile) bond distances in complex 1 are nonequivalent (1.907(8) and 2.034(9) A), leading to the dissociation of one MeCN to form a Y-shaped complex, [Cu(I)(H2CPz2)(MeCN)](ClO4) (3), which is oxidized readily in air to form complex 5 with a butterfly Cu2O2 core.     

Influence of anions on the dimensionality of extended networks based on Cu I cations and 1,4,5,8,9,12-hexaazatriphenylene (HAT) ligands

Reactions of Cu I salts with 1,4,5,8,9,12-hexaazatriphenylene (HAT) afford three types of cationic coordination polymers depending on the anion present in the reaction solution. In the crystal structure of {[Cu(HAT)][BF4]x1/3(C6H6)}infinity, (1), Cu ions and HAT molecules form extended layers that are best described as strongly distorted honeycomb nets. The space between the layers is occupied by [BF4]- anions and solvent molecules. {[Cu(HAT)][PF6]}infinity, (2), crystallizes as a chiral (10,3)-a net with [PF6]- anions residing in the cavities of the three-dimensional metal-organic framework. The crystal structure of {[Cu4(HAT)3][SbF6]4x3C6H6}infinity, (3), is based on unique extended [Cu4(HAT)3]infinity "nanotubules" filled with solvent molecules and [SbF6]- anions.     

Thermal and structural characterization of two polymorphs of Atovaquone and of its chloro derivative

Atovaquone, 2-[4-(4-chlorophenyl)cyclohexyl]-3-hydroxy-1,4-naphthoquinone, is an antimicrobial medicament used to treat or prevent pneumocystis carinii pneumonia, toxoplasmosis and malaria. Two polymorphs of Atovaquone (crystal phases I and III) were isolated and their crystal and molecular structures were determined by single crystal X-ray analysis. In both crystal phases, strong hydrogen bond interactions link adjacent molecules in centrosymmetric dimers. The existence of the different polymorphs is determined by the different orientation of the dimers in the crystal packing. In addition, a crystalline phase of the 2-chloro substituted derivative, which is not stabilized by intermolecular H-bond interactions, was also studied, and compared with those of the pristine (hydroxylic) species. DSC measurements and thermodiffractometry analyses on polycrystalline batches witnessed the 100% purity of the isolated materials and disclosed the crystal-to-crystal interconversion of phase I to phase III upon heating at 210 °C.     

New cuprates featuring ladderlike periodic arrays of [Cu3O8]10- trimeric magnetic nanostructures

A new family of cuprates, Li2Cu3(SiO3)4 (1) and Na2Cu3(GeO3)4 (2), was isolated in molten salt media. The extended lattices contain ladderlike periodic arrays of [Cu3O8]10- magnetic nanostructures. Magnetic properties of the Na2Cu3Ge(4-x)SixO12 series, where x = 0, 0.86, and 1.72, were systematically studied. The geometrically induced magnetic couplings are tunable upon cation substitution.