Synthesis,Structure and Properties of a Binuclear Copper Complex [Cu（Br2hama）（DMF）]2, where Br2hamaH2 = [（3,5-Dibromo-2-hydroxybenzylidene）-amino]-methanesulfonic Acid

The copper（II） compound [Cu（Brzhama）（DMF）]2 （C22H24Br4Cu2N4O10S2, Br2hamaH2 = [（3,5-dibromo-2-hydroxybenzylidene）-amino]-methanesulfonic acid, DMF = N,N＇-dimethylformamide） 1 crystallizes in trictinic, space group P1 with a = 8.477（2）, b = 10.164（2）, c = 10.671（2）A, α= 112.66（3）, β = 104.33（3）, γ = 96.67（3）°, Z = 1, and R = 0.0789 for 1823 observed reflections with I 〉 2σ（I）. The centrosymmetric molecule comprises a pair of copper atoms connected by two anions of [（3,5-dibromo-2-hydroxybenzylidene）-amino]-methanesulfonic acid in a tetradentate coordination mode. The five-coordination of copper（II） is further completed by DME The complex forms a 1-D chain through C-H…π hydrogen bonds. The Cu^II…Cu^II distance is 4.937（1） A.     

A Sandmeyer type reaction for bromination of 2-mercapto-1-methyl-imidazoline (N2C4H6S) into 2-bromo-1-methyl-imidazole (N2C4H5Br) in presence of copper(I) bromide

2-Mercapto-1-methyl-imidazoline (N(2)C(4)H(6)S) is converted at room temperature into 2-bromo-1-methyl-imidazole (N(2)C(4)H(5)Br) in presence of copper(I) bromide in acetonitrile-chloroform mixture via extrusion of sulfur as sulfate and oxidation of Cu(I) into Cu(II). 2-Bromo-1-methyl-imidazole was isolated as its self assembled tetranuclear Cu(II) cluster, [Cu(4)(η(1)-N-(N(2)C(4)H(5)Br)(4)(μ(4)-O)(μ-Br)(6)] 1 {η(1)-N-(N(2)C(4)H(5)Br) = 2-bromo-1-methyl-imidazole}.     

Regioselective formation of 2,5-disubstituted oxazoles via copper(i)-catalyzed cycloaddition of acyl azides and 1-alkynes

The reaction of 1-alkynes with acyl azides in the presence of [Tpm(*,Br)Cu(NCMe)]BF(4) [Tpm(*,Br) = tris(3,5-dimethyl-4-bromopyrazolyl)methane] as the catalyst provides 2,5-oxazoles in moderate to high yields. This is a novel transformation of the CuAAC type that constitutes a significant variation of the commonly observed [3 + 2] cycloaddition reaction to yield 1,2,3-triazoles.     

Five-coordinate aluminum bromides: synthesis, structure, cation formation, and cleavage of phosphate ester bonds

The alkane elimination reaction between Salen((t)Bu)H(2) ligands and diethylaluminum bromide was used to prepare three Salen aluminum bromide compounds salen((t)Bu)AlBr (1) (salen = N,N'-ethylenebis(3,5-di-tert-butylsalicylideneimine)), salpen((t)Bu)AlBr (2) (salpen = N,N'-propylenebis(3,5-di-tert-butylsalicylideneimine)), and salophen((t)Bu)AlBr (3) (salophen = N,N'-o-phenylenenebis(3,5-di-tert-butylsalicylideneimine)). The compounds contain five-coordinate aluminum either in a distorted square pyramidal or a trigonal bipyramidal environment. The bromide group in these compounds could be displaced by triphenylphosphine oxide or triphenyl phosphate to produce the six-coordinate cationic aluminum compounds [salen((t)Bu)Al(Ph(3)PO)(2)]Br (4), [salpen((t)Bu)Al(Ph(3)PO)(2)]Br (5), [salophen((t)Bu)Al(Ph(3)PO)(2)]Br (6), and [salophen((t)Bu)Al[(PhO)(3)PO)](2)]Br (7). All the compounds were characterized by (1)H, (13)C, (27)Al, and (31)P NMR, IR, mass spectrometry, and melting point. Furthermore, compounds 1-3 and 5-7 were structurally characterized by single-crystal X-ray diffraction. Compounds 1-3 dealkylated a series of organophosphates in stoichiometric reactions by breaking the ester C-O bond. Also, they were catalytic in the dealkylation reaction between trimethyl phosphate and added boron tribromide.     

Synthesis of eta1-borazine complexes of palladium and platinum

The eta(1)-borazine complexes trans-[(Cy(3)P)(2)M(Br)(Br(2)B(3)N(3)H(3))] (Cy = cyclohexyl) were prepared by oxidative addition of a B-Br bond of (BrBNH)(3) to [M(PCy(3))(2)] (M = Pd, Pt). Furthermore the platinum compound was converted into the T-shaped cationic complex trans-[(Cy(3)P)(2)Pt(Br(2)B(3)N(3)H(3))][BAr(f)(4)] [Ar(f) = 3,5-(CF(3))(2)C(6)H(3)] by addition of Na[BAr(f)(4)].     

Alzheimer amyloid beta(1-40) peptide: interactions with cationic gemini and single-chain surfactants

The aggregation of amyloid beta-peptide [Abeta(1-40)] into fibril is a key pathological process associated with Alzheimer's disease. The effect of cationic gemini surfactant hexamethylene-1,6-bis-(dodecyldimethylammonium bromide) [C(12)H(25)(CH(3))(2)N(CH(2))(6)N(CH(3))(2)C(12)H(25)]Br(2) (designated as C(12)C(6)C(12)Br(2)) and single-chain cationic surfactant dodecyltrimethylammonium bromide (DTAB) on the Alzheimer amyloid beta-peptide Abeta(1-40) aggregation behavior was studied by microcalorimetry, circular dichroism (CD), and atomic force microscopy (AFM) measurements at pH 7.4. Without addition of surfactant, 0.5 g/L Abeta(1-40) mainly exists in dimeric state. It is found that the addition of the monomers of C(12)C(6)C(12)Br(2) and DTAB may cause the rapid aggregation of Abeta(1-40) and the fibrillar structures are observed by CD spectra and the AFM images. Due to the repulsive interaction among the head groups of surfactants and the formation of a small hydrophobic cluster of surfactant molecules, the fibrillar structure is disrupted again as the surfactant monomer concentration is increased, whereas globular species are observed in the presence of micellar solution. Different from single-chain surfactant, C(12)C(6)C(12)Br(2) has a much stronger interaction with Abeta(1-40) to generate larger endothermic energy at much lower surfactant concentration and has much stronger ability to induce the aggregation of Abeta(1-40).     

Mononuclear Schiff base boron halides: synthesis, characterization, and dealkylation of trimethyl phosphate

A series of mononuclear boron halides of the type LBX(2) [LH = N-phenyl-3,5-di-tert-butylsalicylaldimine, X = Cl (2), Br (3)] and LBX [LH2 = N-(2-hydroxyphenyl)-3,5-di-tert-butylsalicylaldimine, X = Cl (7), Br (8); LH2 = N-(2-hydroxyethyl)-3,5-di-tert-butylsalicylaldimine, X = Cl (9), Br (10); and LH2 = N-(3-hydroxypropyl)-3,5-di-tert-butylsalicylaldimine, X = Cl (11), Br (12)] were synthesized from their borate precursors LB(OMe)2 (1) (LH = N-phenyl-3,5-di-tert-butylsalicylaldimine) and LB(OMe) [LH2 = N-(2-hydroxyphenyl)-3,5-di-tert-butylsalicylaldimine (4), N-(2-hydroxyethyl)-3,5-di-tert-butylsalicylaldimine (5), N-(3-hydroxypropyl)-3,5-di-tert-butylsalicylaldimine (6)]. The boron halide compounds were air and moisture sensitive, and upon hydrolysis, compound 7 resulted in the oxo-bridged compound 13 that contained two seven-membered boron heterocycles. The boron halide compounds dealkylated trimethyl phosphate in stoichiometric reactions to produce methyl halide and unidentified phosphate materials. Compounds 8 and 12 were found to be the most effective dealkylating agents. On reaction with tert-butyl diphenyl phosphinate, compound 8 produced a unique boron phosphinate compound LB(O)OPPh2 (14) containing a terminal phosphinate group. Compounds 1-14 were characterized by 1H, 13C, 11B, 31P NMR, IR, MS, EA, and MP. Compounds 5, 6, and 11-14 also were characterized by single-crystal X-ray diffraction.     

Interactions of an asymmetric amine with a non-C2 symmetric Cu-salen complex: an EPR/ENDOR and HYSCORE investigation

Single enantiomers of R-/S-methylbenzylamine (MBA) were found to selectively form adducts with the chiral non-C(2) symmetric Cu-salen complex N-(3,5-di-tert-butylsalicylidene)-N'-(salicylidene)-cyclohexane-1,2-diamine copper(II), hereafter labelled [Cu(3)]. The g/A spin Hamiltonian parameters of this Cu(II) complex showed a decrease in symmetry from axial to rhombic upon formation of the [Cu(3)] + MBA adducts. The selectivity in enantiomeric discrimination was found to be only 59 ± 5% in favour of the heterochiral R,R'-[Cu(3)] + S-MBA and S,S'-[Cu(3)] + R-MBA adducts. This was directly evidenced by W-band EPR spectroscopy. The observed low selectivity for enantiomer discrimination is primarily attributed to the loss of the bulky tert-butyl groups from the 3,5 positions of [Cu(3)] compared to the parent N,N'-bis(3,5-di-tert-butylsalicylidene)-cyclohexane-1,2-diamine copper(II) ligand (labelled [Cu(1)]). The structure of the [Cu(3)] complex in the presence and absence of coordinating amine was further investigated by analysis of the ligand hyperfine interactions, as revealed through Q-band CW-ENDOR, X-band Davies ENDOR and HYSCORE. (1)H couplings from the -NH(2) group of the amine, observed by ENDOR and HYSCORE, provided direct evidence of amine coordination.     

Di- and tetranuclear copper(I) complexes containing phenylaminobis(phosphonite), PhN{P(OC6H4OMe-o)2}2, and their reactivity toward bipyridyl ligands

The aminobis(phosphonite) PhN(P(OC6H4OMe-o)2)2 (PNP; 1) reacts with 2 equiv of CuI to give a binuclear complex, Cu2(mu2-I)2(NCCH3)2(mu-PNP) (2), whereas similar reactions with CuCl and CuBr furnish tetranuclear "ladder"-type complexes, Cu4(mu2-X)2(mu3-X)2(mu-PNP)2 (3, X = Cl; 4, X = Br), in excellent yield. The complex 2 when heated under vacuum turns into the tetranuclear complex 5 in a reversible fashion. Similarly, the complexes 3 and 4 on dissolution in CH3CN dissociate reversibly into the corresponding binuclear complexes from which the tetrameric complexes can be readily regenerated. Treatment of 2 with excess of pyridine produces the heterosubstituted derivative, Cu2(mu2-I)2(C5H5N)2(mu-PNP) (6). The interaction of 2 with 2,2'-bipyridine in 1:1 and 1:2 ratios produces the mono- and disubstituted derivatives, Cu2(mu2-I)I(C10H8N2)(mu-PNP) (7) and [Cu2(mu2-I)(C10H8N2)2(mu-PNP)]I (8), respectively. The chloro and bromo analogues of 7 are prepared by treating the tetranuclear derivatives 3 and 4 with 2,2'-bipyridine. Reaction of 2 with 4,4'-bipyridine in the presence of AgOTf gives the cationic complex [Cu4(NCCH3)4(C10H8N2)2(mu-PNP)2](OTf)4 (9), whereas the complex [Cu2(NCCH3)2(mu-PNP)2](OTf)2 (10) was obtained from the reaction of 2 with 1 equiv of 1 and AgOTf. The reactions of 3 and 4 with 2 equiv of 4,4'-bipyridine in acetonitrile afford one-dimensional copper(I) coordination polymers [Cu2(mu2-X)2(mu-PNP)(C10H8N2)]n (13, X = Cl; 14, X = Br). The molecular structures of 2-4, 6-8, 12, and 14 are confirmed by X-ray crystallography.     

Copper(II) complexes of a series of alkoxy diazine ligands: mononuclear, dinuclear, and tetranuclear examples with structural, magnetic, and DFT studies

Picolyl hydrazide ligands have two potentially bridging functional groups (micro-O, micro-N-N) and consequently can exist in different coordination conformers, both of which form spin-coupled polynuclear coordination complexes, with quite different magnetic properties. The complex [Cu(2)(POAP-H)Br(3)(H(2)O)] (1) involves a micro-N-N bridge (Cu-N-N-Cu 150.6 degrees ) and exhibits quite strong antiferromagnetic coupling (-2J = 246(1) cm(-)(1)). [Cu(2)(PZOAPZ-H)Br(3)(H(2)O)(2)] (2) has two Cu(II) centers bridged by an alkoxide group with a very large Cu-O-Cu angle of 141.7 degrees but unexpectedly exhibits quite weak antiferromagnetic exchange (-2J = 91.5 cm(-)(1)). This is much weaker than anticipated, despite direct overlap of the copper magnetic orbitals. Density functional calculations have been carried out on compound 2, yielding a similar singlet-triplet splitting energy. Structural details are reported for [Cu(2)(POAP-H)Br(3)(H(2)O)] (1), [Cu(2)(PZOAPZ-H)Br(3)(H(2)O)(2)] (2), [Cu(2)(PAOPF-2H)Br(2)(DMSO)(H(2)O)].H(2)O (3), [Cu(4)(POMP-H))(4)](NO(3))(4).2H(2)O (4), and PPOCCO (5) (a picolyl hydrazide ligand with a terminal oxime group) and its mononuclear complexes [Cu(PPOCCO-H)(NO(3))] (6) and [Cu(PPOCCO-H)Cl] (7). Compound 1 (C(12)H(13)Br(3)Cu(2)N(5)O(4)) crystallizes in the monoclinic system, space group P2(1)/c, with a = 15.1465(3) A, b = 18.1848(12) A, c = 6.8557(5) A, beta = 92.751(4) degrees, and Z = 4. Compound 2 (C(10)H(13)Br(3)Cu(2)N(7)O(4)) crystallizes in the triclinic system, space group P, with a = 9.14130(1) A, b = 10.4723(1) A, c = 10.9411(1) A, alpha = 100.769(1), beta = 106.271(1) degrees, gamma = 103.447(1) degrees, and Z = 2. Compound 3 (C(23)H(22)Br(2)Cu(2)N(7)O(5.5)S) crystallizes in the monoclinic system, space group P2(1)/c, with a = 12.406(2) A, b = 22.157(3) A, c = 10.704(2) A, beta = 106.21(1) degrees, and Z = 4. Compound 4(C(52)H(48)Cu(4)N(20)O(18)) crystallizes in the monoclinic system, space group P2(1)/n, with a = 14.4439(6) A, b = 12.8079(5) A, c = 16.4240(7) A, beta = 105.199(1) degrees, and Z = 4. Compound 5 (C(15)H(14)N(4)O(2)) crystallizes in the orthorhombic system, space group Pna2(1), with a = 7.834(3) A, b = 11.797(4) A, c = 15.281(3) A, and Z = 4. Compound 6(C(15)H(13)CuN(5)O(5)) crystallizes in the monoclinic system, space group P2(1)/c, with a = 8.2818(9) A, b = 17.886(2) A, c = 10.828(1) A, beta = 92.734(2) degrees, and Z = 4. Compound 7 (C(15)H(13)CuClN(4)O(2)) crystallizes in the orthorhombic system, space group Pna2(1), with a = 7.9487(6) A, b = 14.3336(10) A, c = 13.0014(9) A, and Z = 4. Density functional calculations on PPOCCO are examined in relation to the anti-eclipsed conformational change that occurs on coordination to copper(II).     

Construction of halide-bridged tungsten-copper-sulfide double cubanelike clusters from a new precursor [(Tp*WS2)2(μ-S2)

Treatment of [Et(4)N][Tp*WS(3)] (1) (Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate) with 2 equiv of AgSCN in MeCN afforded a novel neutral compound [(Tp*WS(2))(2)(μ-S(2))] (2). Reactions of 2 with excess CuX (X = Cl, Br, I) in MeCN and CH(2)Cl(2) or CHCl(3) formed three neutral W/Cu/S clusters [{Tp*W(μ(3)-S)(3)Cu(3)(μ-Cl)}(2)Cu(μ-Cl)(2)(μ(7)-Cl)(MeCN)](2) (3), [{Tp*W(μ(3)-S)(3)Cu(3)}(2)Br(μ-Br)(2)(μ(4)-Br)(MeCN)] (4), and [{Tp*W(μ(3)-S)(3)Cu(3)}(2){Cu(2)(μ-I)(4)(μ(3)-I)(2)}] (5), respectively. On the other hand, treatment of 2 with CuX (X = Cl, Br) in the presence of Et(4)NX (X = Cl, Br) produced two anionic W/Cu/S clusters [Et(4)N][{Tp*W(μ(3)-S)(3)Cu(3)X}(2)(μ-X)(2)(μ(4)-X)] (6: X = Cl; 7 X = Br). Compounds 2-7 were characterized by elemental analysis, IR, UV-vis, (1)H NMR, electrospray ionization (ESI) mass spectra, and single-crystal X-ray crystallography. The dimeric structure of 2 can be viewed as two [Tp*WS(2)] fragments in which two W atoms are connected by one S(2)(2-) dianion. Compounds 3-7 all possess unique halide-bridged double cubanelike frameworks. For 3, two [Tp*W(μ(3)-S)(3)Cu(3)](2+) dications are linked via a μ(7)-Cl(-) bridge, two μ-Cl(-) bridges, and a [Cu(MeCN)(μ-Cl)(2)](+) bridge. For 4, one [Tp*W(μ(3)-S)(3)Cu(3)(MeCN)](2+) dication and one [Tp*W(μ(3)-S)(3)Cu(3)Br](+) cation are linked via a μ(4)-Br(-) and two μ-Br(-) bridges. For 5, the two [Tp*W(μ(3)-S)(3)Cu(3)](2+) dications are bridged by a linear [(μ-I)(2)Cu(μ(3)-I)(2)Cu(μ-I)(2)](4+) species. For 6 and 7, two [Tp*W(μ(3)-S)(3)Cu(3)X](+) cations are linked by a μ(4)-X(-) and two μ-X(-) bridges (X = Cl, Br). In addition, the third-order nonlinear optical (NLO) properties of 2-7 in MeCN/CH(2)Cl(2) were investigated by using femtosecond degenerate four-wave mixing (DFWM) technique.     

Polyfluorinated Tris(pyrazolyl)borates. Syntheses and Spectroscopic and Structural Characterization of Group 1 and Group 11 Metal Complexes of [HB(3,5-(CF(3))(2)Pz)(3)](-) and [HB(3-(CF(3))Pz)(3)](-)

The fluorinated tris(pyrazolyl)borate ligands [HB(3,5-(CF(3))(2)Pz)(3)](-) and [HB(3-(CF(3))Pz)(3)](-) (where Pz = pyrazolyl) have been synthesized as their sodium salts from the corresponding pyrazoles and NaBH(4) in high yield. These sodium complexes and the related [HB(3,5-(CF(3))(2)Pz)(3)]K(DMAC) were used as ligand transfer agents in the preparation of the copper and silver complexes [HB(3,5-(CF(3))(2)Pz)(3)]Cu(DMAC), [HB(3,5-(CF(3))(2)Pz)(3)]CuPPh(3), [HB(3,5-(CF(3))(2)Pz)(3)]AgPPh(3), and [HB(3-(CF(3))Pz)(3)]AgPPh(3). Metal complexes of the fluorinated [HB(3,5-(CF(3))(2)Pz)(3)](-) ligand have highly electrophilic metal sites relative to their hydrocarbon analogs. This is evident from the formation of stable adducts with neutral oxygen donors such as H(2)O, dimethylacetamide, or thf. Furthermore, the metal compounds derived from fluorinated ligands show fairly long-range coupling between fluorines of the trifluoromethyl groups and the hydrogen, silver, or phosphorus. The solid state structures show that the fluorines are in close proximity to these nuclei, thus suggesting a possible through-space coupling mechanism. Crystal structures of the sodium adducts exhibit significant metal-fluorine interactions. The treatment of [HB(3,5-(CF(3))(2)Pz)(3)]Na(H(2)O) with Et(4)NBr led to [Et(4)N][HB(3,5-(CF(3))(2)Pz)(3)], which contains a well-separated [Et(4)N](+) cation and the [HB(3,5-(CF(3))(2)Pz)(3)](-) anion in the solid state. Crystal data with Mo Kalpha (lambda = 0.710 73 ?) at 193 K: [HB(3,5-(CF(3))(2)Pz)(3)]Na(H(2)O), C(15)H(6)BF(18)N(6)NaO, a = 7.992(2) ?, b = 15.049(2) ?, c = 9.934(2) ?, beta = 101.16(2) degrees, monoclinic, P2(1)/m, Z = 2; [{HB(3-(CF(3))Pz)(3)}Na(thf)](2), C(32)H(30)B(2)F(18)N(12)Na(2)O(2), a = 9.063(3) ?, b = 10.183(2) ?, c = 12.129(2) ?, alpha = 94.61(1) degrees, beta = 101.16(2) degrees, gamma = 95.66(2) degrees, triclinic, &Pmacr;1, Z = 1; [HB(3,5-(CF(3))(2)Pz)(3)]Cu(DMAC), C(19)H(13)BCuF(18)N(7)O, a = 15.124(4) ?, b = 8.833(2) ?, c = 21.637(6) ?, beta = 105.291(14) degrees, monoclinic, P2(1)/n, Z = 4; [HB(3,5-(CF(3))(2)Pz)(3)]CuPPh(3), C(33)H(19)BCuF(18)N(6)P, a = 9.1671(8) ?, b = 14.908(2) ?, c = 26.764(3) ?, beta = 94.891(1) degrees, monoclinic, P2(1)/c, Z = 4; [HB(3,5-(CF(3))(2)Pz)(3)]AgPPh(3).0.5C(6)H(14), C(36)H(26)AgBF(18)N(6)P, a = 13.929(2) ?, b = 16.498(2) ?, c = 18.752(2) ?, beta = 111.439(6) degrees, monoclinic, P2(1)/c, Z = 4; [Et(4)N][HB(3,5-(CF(3))(2)Pz)(3)], C(23)H(24)BF(18)N(7), a = 10.155(2) ?, b = 18.580(4) ?, c = 16.875(5) ?, beta = 99.01(2) degrees, monoclinic, P2(1)/n, Z = 4.     

Copper halide-bridged ruthenium telluride carbonyl complexes: discovery of the semiconducting cluster chain polymer {[PPh4]2[Te2Ru4(CO)10Cu4Br2Cl2].THF}infinity

A new series of Te-Ru-Cu carbonyl complexes was prepared by the reaction of K(2)TeO(3) with [Ru(3)(CO)(12)] in MeOH followed by treatment with PPh(4)X (X=Br, Cl) and [Cu(MeCN)(4)]BF(4) or CuX (X=Br, Cl) in MeCN. When the reaction mixture of K(2)TeO(3) and [Ru(3)(CO)(12)] was first treated with PPh(4)X followed by the addition of [Cu(MeCN)(4)]BF(4), doubly CuX-bridged Te(2)Ru(4)-based octahedral clusters [PPh(4)](2)[Te(2)Ru(4)(CO)(10)Cu(2)X(2)] (X=Br, [PPh(4)](2)[1]; X=Cl, [PPh(4)](2)[2]) were obtained. When the reaction mixture of K(2)TeO(3) and [Ru(3)(CO)(12)] was treated with PPh(4)X (X=Br, Cl) followed by the addition of CuX (X=Br, Cl), three different types of CuX-bridged Te-Ru carbonyl clusters were obtained. While the addition of PPh(4)Br or PPh(4)Cl followed by CuBr produced the doubly CuBr-bridged cluster 1, the addition of PPh(4)Cl followed by CuCl led to the formation of the Cu(4)Cl(2)-bridged bis-TeRu(5)-based octahedral cluster compound [PPh(4)](2)[{TeRu(5)(CO)(14)}(2)Cu(4)Cl(2)] ([PPh(4)](2)[3]). On the other hand, when the reaction mixture of K(2)TeO(3) and [Ru(3)(CO)(12)] was treated with PPh(4)Br followed by the addition of CuCl, the Cu(Br)CuCl-bridged Te(2)Ru(4)-based octahedral cluster chain polymer {[PPh(4)](2)(Te(2)Ru(4)(CO)(10)Cu(4)Br(2)Cl(2)).THF}(infinity) ({[PPh(4)](2)[4].THF}(infinity)) was produced. The chain polymer {[PPh(4)](2)[4].THF}(infinity) is the first ternary Te-Ru-Cu cluster and shows semiconducting behavior with a small energy gap of about 0.37 eV. It can be rationalized as resulting from aggregation of doubly CuX-bridged clusters 1 and 2 with two equivalents of CuCl or CuBr, respectively. The nature of clusters 1-4 and the formation and semiconducting properties of the polymer of 4 were further examined by molecular orbital calculations at the B3LYP level of density functional theory.     

Butterfly and Nest-Shaped Tp*-W-Cu-S Cluster Monomers and Dimers with Hexamethylenetetramine as Ligand: Anion-Dependent Structures and Nonlinear Optical Properties

The assembly of[Et4N][Tp*WS3](1) with CuX (Tp* =hydridotris(3,5-dimethylpyrazol-1-yl)borate;X =Cl,Br,and I) or[Cu(MeCN)4][PF6]in the presence of tetratopic liga...     

Cobalt(II), nickel(II), copper(II), and zinc(II) complexes with [3(5)]adamanzane, 1,5,9,13-tetraazabicyclo[7.7.3]nonadecane, and [(2.3)(2).2(1)] adamanzane, 1,5,9,12-tetraazabicyclo[7.5.2]hexadecane

Isolation of the free bicyclic tetraamine, [3(5)]adamanzane.H(2)O (1,5,9,13-tetraazabicyclo[7.7.3]nonadecane.H(2)O), is reported along with the synthesis and characterization of a copper(II) complex of the smaller macrocycle [(2.3)(2).2(1)]adamanzane (1,5,9,12-tetraazabicyclo[7.5.2]hexadecane) and of three cobalt(II), four nickel(II), one copper(II), and two zinc(II) complexes with [3(5)]adamanzane. For nine of these compounds (2-8, 10b, and 12) the single-crystal X-ray structures were determined. The coordination geometry around the metal ion is square pyramidal in [Cu([(2.3)(2).2(1)]adz)Br]ClO(4) (2) and trigonal bipyramidal in the isostructural structures [Cu([3(5)]adz)Br]Br (3), [Ni([3(5)]adz)Cl]Cl (5), [Ni([3(5)]adz)Br]Br (6), and [Co([3(5)]adz)Cl]Cl (8). In [Ni([3(5)]adz)(NO(3))]NO(3) (4) and [Ni([3(5)]adz)(ClO(4))]ClO(4) (7) the coordination geometry around nickel(II) is a distorted octahedron with the inorganic ligands at cis positions. The coordination polyhedron around the metal ion in [Co([3(5)]adz)][ZnCl(4)] (10b) and [Zn([3(5)]adz)][ZnCl(4)] (12) is a slightly distorted tetrahedron. Anation equilibrium constants were determined spectrophotometrically for complexes 2-6 at 25 and 40 degrees C and fall in the region 2-10 M(-1) for the halide complexes and 30-65 M(-1) for the nickel(II) nitrate complex (4). Rate constants for the dissociation of the macrocyclic ligand from the metal ions in 5 M HCl were determined for complexes 2, 3, 5, 8, 10, and 12. The reaction rates vary from half-lives at 40 degrees C of 14 min for the dissociation of the Zn([3(5)]adz)(2+) complex (12) to 14-15 months for the Ni([3(5)]adz)Cl(+) ion (5).     

Novel Mixed Complexes of Copper(II) and Ethylenediamine: Synthesis,Crystal Structure,and Catalytic Activity in the Cross-Coupling Reaction of 1-Phenyl-5<Emphasis Type="Italic">H</Emphasis>-tetrazole-5-thiol and Iodobenzene

Two earlier unknown complexes, [Cu(en)₂(Hptt)]Br (Hptt = 1-phenyl-1H-terazole-5-thiol, en = ethylenediamine) and trans-[Cu(en)2(H2O)Br]Br, have been synthesized and characterized using X-ray diffraction analysis. In [Cu(en)₂(Hptt)]Br complex, the copper cation is bonded with the N⁴ atom of tetrazole ring. Catalytic activity of the obtained complexes in cross-coupling reaction of 1-phenyl-5H-tetrazole-5-thiol with iodobenzene is comparable to that of CuBr₂ in the presence of 2 eq. of ethylenediamine.     

Two enantiomers of [Cu(3)(mnt)(3)](3-) as ligands to Cu(i) or Ag(i) in building [Cu(6)M(2)(mnt)(6)](4-) complexes (M = Cu or Ag) with the reversal of the reaction by X(-) (X = Cl, Br)

Two enantiomers of [Bu(4)N](3)[Cu(3)(mnt)(3)] () formed by Na(2)(mnt) (mnt = maleonitriledithiolate, [S(2)C(2)(CN)(2)](2-)) and CuCl in a 1 : 1 molar ratio react further with MCl (M = Cu or Ag) involving both the enantiomers of to produce the larger complex, [Bu(4)N](4)[Cu(6)M(2)(mnt)(6)] (M = Cu (2), Ag (3)) from which the capped Cu(+) or Ag(+) ion can readily be removed by Bu(4)NX (X = Cl, Br), reverting or back to . Such reversal does not work with non-coordinating anions like BF(4)(-), ClO(4)(-) and PF(6)(-).     

Trinuclear-based copper(I) pyrazolate polymers: effect of trimer π-acid···halide/pseudohalide interactions on the supramolecular structure and phosphorescence

Under different situations, solvothermal reactions of 3,5-diethyl-4-(4-pyridyl)-pyrazole (HL) with CuX or CuX(2) (X = Cl, Br, I, and SCN) afforded five copper(I) coordination polymers, {CuX[CuL](3)·solvent}(n) (X = Cl, 1; Br, 2; I, 3; X = SCN and solvent = MeCN, 4) and {Cu(2)I(2)[CuL](3)}(n) (5). X-ray diffraction analyses show that all the complexes have trinuclear [CuL](3) (referred as Cu(3)) secondary building units featuring planar nine-membered Cu(3)N(6) metallocycles with three peripheral pyridyl groups as connectors, which are further linked by CuX or Cu(2)X(2) motifs to generate single- or double-strand chains. Interestingly, the Cu(I) atoms within the Cu(3) units in 1-5 behave as coordinatively unsaturated π-acid centers to contact soft halide/pseudohalide X atoms of CuX and Cu(2)X(2) motifs, which lead to novel sandwich substructures of [(Cu(3))(Cu(2)X(2))(Cu(3))] (X = Br, I, and SCN) in 2-4. In addition, both the π-acid [Cu(3)]···X contacts and intertrimer Cu···Cu interactions contribute to the one-dimensional (1D) double-strand and 2D/3D supramolecular structures of 1-5. All of these complexes exhibit high thermostability and bright solid-state phosphorescence upon exposure to UV radiation at room temperature. The emissions arise from the mixtures of metal-centered charge transfer, metal to ligand charge transfer, and halide-to-ligand charge transfer excited states, and can be tuned by intermolecular π-acid [Cu(3)]···halide/pseudohalide contacts.     

Four [Tp*W(μ3-S)3Cu3(μ3-Br)]-based clusters: synthesis, structural characterization and third-order NLO properties

Treatment of [Et(4)N][Tp*W(μ(3)-S)(3)(CuBr)(3)] (Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate) (1) with an excess of α-methylpyridine (α-MePy) and NH(4)PF(6) in CH(2)Cl(2) afforded a cationic cluster [Tp*W(μ(3)-S)(3)Cu(3)(α-MePy)(3)(μ(3)-Br)](PF(6)) (2) while the reaction of 1 with an excess of 1,4-pyrazine (1,4-pyz) and NH(4)PF(6) in MeCN-CH(2)Cl(2) at 65 °C produced a polymeric cluster [Tp*W(μ(3)-S)(3)Cu(3)(1,4-pyz)((1,4-pyz)(0.5))(2)(μ(3)-Br)][Tp*W(μ(3)-S)(3)(CuBr)(3)] (3). Reactions of 1 with melamine (MA) in 1:1 or 1:2 gave rise to another polymeric cluster [{Tp*W(μ(3)-S)(3)Cu(3)Br(μ(3)-Br)}(2)(MA)(2)] (4) and a neutral cluster [Tp*W(μ(3)-S)(3)Cu(3)Br(μ(3)-Br)(MA)(2)] (5), respectively. Compounds 2-5 were characterized by elemental analysis, IR spectra, UV-vis spectra, (1)H NMR, electrospray ionization (ESI) mass spectra and X-ray crystallography. The cation of 2 has a cubane-like [Tp*W(μ(3)-S)(3)Cu(3)(μ(3)-Br)] structure with each α-MePy ligand coordinated at one Cu(i) center. For 3, each [Tp*W(μ(3)-S)(3)Cu(3)(μ(3)-Br)] core is interconnected by 1,4-pyz bridges to form a 1D cationic zigzag chain with the [Tp*W(μ(3)-S)(3)(CuBr)(3)](-) anions arranged along its two sides. For 4, each [Tp*W(μ(3)-S)(3)Cu(3)(μ(3)-Br)] core is interlinked by MA bridges to afford a 1D spiral chain. 5 adopts a cubane-like [Tp*W(μ(3)-S)(3)Cu(3)(μ(3)-Br)] structure in which one terminal Br and two MA ligands are coordinated at three Cu centers. The third-order nonlinear optical (NLO) properties of 1-5 in DMF were investigated by femtosecond degenerate four-wave mixing (DFWM) technique with a 80 fs pulse width at 800 nm. Compounds 1-5 exhibit good NLO responses, and 3 and 4 possess the largest second-order hyperpolarizability γ values among the known W/Cu/S clusters bearing the [Tp*WS(3)] unit.     

Probing the Presence of Multiple Metal-Metal Bonds in Technetium Chlorides by X-ray Absorption Spectroscopy: Implications for Synthetic Chemistry

The cesium salts of [Tc(2)X(8)](3-) (X = Cl, Br), the reduction product of (n-Bu(4)N)[TcOCl(4)] with (n-Bu(4)N)BH(4) in THF, and the product obtained from reaction of Tc(2)(O(2)CCH(3))(4)Cl(2) with HCl(g) at 300 °C have been characterized by extended X-ray absorption fine structure (EXAFS) spectroscopy. For the [Tc(2)X(8)](3-) anions, the Tc-Tc separations found by EXAFS spectroscopy (2.12(2) ? for both X = Cl and Br) are in excellent agreement with those found by single-crystal X-ray diffraction (SCXRD) measurements (2.117[4] ? for X = Cl and 2.1265(1) ? for X = Br). The Tc-Tc separation found by EXAFS in these anions is slightly shorter than those found in the [Tc(2)X(8)](2-) anions (2.16(2) ? for X = Cl and Br). Spectroscopic and SCXRD characterization of the reduction product of (n-Bu(4)N)[TcOCl(4)] with (n-Bu(4)N)BH(4) are consistent with the presence of dinuclear species that are related to the [Tc(2)Cl(8)](n-) (n = 2, 3) anions. From these results, a new preparation of (n-Bu(4)N)(2)[Tc(2)Cl(8)] was developed. Finally, EXAFS characterization of the product obtained from reaction of Tc(2)(O(2)CCH(3))(4)Cl(2) with HCl(g) at 300 °C indicates the presence of amorphous α-TcCl(3). The Tc-Tc separation (i.e., 2.46(2) ?) measured in this compound is consistent with the presence of Tc═Tc double bonds in the [Tc(3)](9+) core.