Rectangle and [2]catenane from cluster modular construction

A cluster rectangle and a [2]catenane, respectively, featuring P^N-type and cuboidal cluster subunits are synthesized from cluster modular constructions.

Tungsten(VI)-Copper(I)-Sulfur Cluster-Supported Metal-Organic Frameworks Bridged by in Situ Click-Formed Tetrazolate Ligands

Six analogous two-dimensional (2D) [Tp*WS₃Cu₃]-based (Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate) networks, namely, {[(Tp*WS₃Cu₃)₂L₃](μ₃-N₃)}_n (2: L = 5-methyltetrazolate (Mtta); 3a: L = 5-ethyltetrazolate (Etta)) and {[(Tp*WS₃Cu₃)₂L₃]BF₄}_n (3b: L = Etta; 4: L = 5-propyltetrazolate (Ptta); 5: L = 5-butyltetrazolate (Btta); 6: L = 5-pentyltetrazolate (Petta)) were synthesized by reactions of [Et₄N][Tp*WS₃] (1), [Cu(CH₃CN)₄]BF₄, NaN₃, and NH₄BF₄ in different nitrile solvents (CH₃(CH₂)_nCN, n = 0, 1, 2, 3, and 4) under solvothermal conditions. In the structures of 2-6, each alkyl tetrazolate L as a bridging ligand was generated in situ from the "click" reaction between azide and nitrile. These 2D (6,3) networks support two types of voids wherein the pendant alkyl groups are accommodated. A tetrahedron cage-like cluster [Tp*W(μ₃-S)₃(μ₃-S')Cu₃]₄ (7) was also formed in some of the above reactions and can be readily separated by solvent extraction. The proportion of 7 increased with the elongation of the alkyl chains and finally became the exclusive product when heptylnitrile was employed. Further use of CuCN as a surrogate for [Cu(CH₃CN)₄]BF₄ with the aim of introducing additional CN bridges into the network led us to isolate a tetrazolate-free compound, {[Et₄N]{(Tp*WS₃Cu₃)[Cu₂(CN)_4.5]}₂·2PhCH₂CN}_n (8·2PhCH₂CN), a unique 2D network that features {(Tp*WS₃Cu₃)[Cu₂(CN)₅]}₂^2-, {(Tp*WS₃Cu₃)₃[Cu₃(CN)₇]₂[Cu(CN)₃]}^4-, and {(Tp*WS₃Cu₃)[Cu₄(CN)₉]}₂^6- ring subunits. Compounds 5-8 are soluble in DMF and exhibit a reverse saturable absorption and self-focusing third-order nonlinear optical (NLO) effect at 532 nm with hyperpolarizability γ values in the range of 4.43 × 10^-30 to 5.40 × 10^-30 esu, which are 400-500 times larger than that of their precursor 1. The results provide an interesting insight into the synergetic synthetic strategy related to the assembly of the [Tp*WS₃Cu₃]²⁺ cluster core, the "click" formation of the tetrazolate ligands, and the construction of the [Tp*WS₃Cu₃]²⁺ cluster-based 2D networks.

Crystal structures and third-order optical properties of three manganese(II) complexes constructed from N-heterocyclic and polycarboxylate ligands

Three new manganese(II) complexes, {[Mn(PTP)]2[Mn(PTP)(H2O)]}(BTA)2·2H2O (1), [Mn(PTP)(ODA)]2 (2), and [Mn(FTP)(ODA)]2·H2O (3), were synthesized by the reactions of manganese acetate and polycarboxylic acid in the presence of N-heterocyclic ligands (where PTP=4′-phenyl-2,2′:6′,2″-terpyridine, H3BTA=benzene-1,3,5-tricarboxylic acid, H2ODA=4,4′-oxydibenzoic acid, FTP=4′-(furan-2-yl)-2,2′:6′,2″-terpyridine). In complex 1, each BTA ligand serves as a μ 3-bridge to link three Mn(II) centers, whereas each Mn(II) center is coordinated by two BTA ligands. This connection mode results in a grid sheet. Complexes 2 and 3 have very similar molecular structures with Mn(II) centers connected by ODA ligands to result in ring-like arrays. We investigated the third-order nonlinear optical (NLO) properties of the three complexes by single beam Z-scan techniques. Complexes 1–3 exhibit strong third-order NLO reverse saturable absorption with NLO absorptive indices β=1.32×10−6, 3.01×10−6, and 9.42×10−6 m W−1, respectively. In addition, complex 1 shows all excellent self-focusing effect with an NLO refractive index of γ=1.25×10−12 m2 W−1. The third-order NLO susceptibility χ (3) of the three complexes were calculated as 47.55×10−8, 4.85×10−8, and 15.16×10−8 esu, respectively.

Diverse Tp*-Capped W-Cu-S Clusters from One-Pot Assembly Involving in Situ Thiolation of Phosphines

In the absence/presence of S8, the one-pot assembly of [Et4N][Tp*WS3] [1; Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate] with [Cu(MeCN)4]PF6 and bis- or tetraphosphine ligands 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,4-bis(diphenylphosphino)butane (dppb), and N,N,N',N'-tetrakis(diphenylphosphinomethyl)ethylenediamine (dppeda) produces six W-Cu-S clusters, namely, [(Tp*WS3Cu2Cl)2(dppe)] (2), [Tp*WS3Cu4(dppp)2(μ4-Cl)(μ-Cl)]PF6·MeCN (3·MeCN), [(Tp*WS3Cu3)2(μ4-Cl)(μ-Cl)2(dpppS2)] (4), [(Tp*WS3Cu2Cl)2(dppbS2)]·2MeCN·2H2O (5·2MeCN·2H2O), [(Tp*WS3Cu3Cl2)2(dppbS2)] (6), and [(Tp*WS3Cu3)2(Ph2PS2)3(μ6-Cl)0.5](PF6)0.5·0.75CH2Cl2 (7·0.75CH2Cl2). Compounds 2-7 are characterized by elemental analysis, IR, UV-vis, (1)H and (31)P{(1)H} NMR, electrospray ionization mass spectrometry, and X-ray crystallography. For 2, the dppe ligand bridges a pair of butterfly-shaped [Tp*WS3Cu2] cores to form a double-butterfly-shaped structure. For 4, the dppp ligand is susceptible toward S association and forms an in situ generated dpppS2 ligand, supporting an octanuclear double-half-open-cubane structure and contrasting an analogous system wherein a pentanuclear motorcycle-shaped cationic cluster 3 is formed with the absence of S8. A longer dppb ligand readily converts to S-based ligands in 5 and 6, subsequently serving as bridges between a pair of a butterfly-shaped (5) and nest-shaped (6) clusters. Further use of a tetraphosphine ligand, dppeda, in the cluster formation, with the presence of S8, leads to an unexpected ligand degradation to give the [Ph2PS2](-) anions. Three [Ph2PS2](-) anions juxtapose a pair of nest-shaped cluster cores to yield an octanuclear cluster, 7, featuring a cage to encapsulate μ6-Cl(-). The third-order nonlinear-optical (NLO) properties of 2-7 in N,N-dimethylformamide, investigated using a Z-scan technique at 532 nm, show that 2-6 have a reverse saturable absorption, while 7 has a notable saturable absorption. All of 2-7 exhibit a self-focusing effect with hyperpolarizability γ values in the range of 4.71 × 10(-30)-1.02 × 10(-29) esu, which are 440-1000 times higher than that of 1. The formation of 4-7 from 1 through the in situ thiolation of phosphine ligands presents a new approach to the design and assembly of the W-Cu-S clusters with interesting structural arrays and better NLO properties.

Rational construction of functional molybdenum (tungsten)–copper–sulfur coordination oligomers and polymers from preformed cluster precursors

Discrete Mo(W)–Cu–S clusters are used as precursors and building blocks for a diverse array of cluster-supported coordination oligomers and polymers.

Bioinorganic modeling chemistry of carbon monoxide dehydrogenases: description of model complexes, current status and possible future scopes

Carbon monoxide dehydrogenases (CODHs) use CO as their sole source of carbon and energy and are found in both aerobic and anaerobic carboxidotrophic bacteria. Reversible transformation of CO to CO2 is catalyzed by a bimetallic [Mo-(μ2-S)-Cu] system in aerobic and by a highly asymmetric [Ni-Fe-S] cluster in anaerobic CODH active sites. The CODH activity in the microorganisms effects the removal of almost 10(8) tons of CO annually from the lower atmosphere and earth and thus help to maintain a sub-toxic concentration of CO. Despite an appreciable amount of work, the mechanism of CODH activity is not clearly understood yet. Moreover, biomimetic chemistry directed towards the active sites of CODHs faces several synthetic challenges. The synthetic problems associated with the modeling chemistry and strategies adopted to overcome those problems are discussed along with their limitations. A critical analysis of the exciting results delineating the present status of CODH modeling chemistry and its future prospects are presented.

Structures and third-order nonlinear optical properties of two three-dimensional Cd(ii) coordination polymers with trinodal (3, 4, 5) and dinodal (4, 5) connected network topologies

We reported two Cd(ii) coordination polymers with trinodal (3, 4, 5) and dinodal (4, 5) connected network topologies. Two compounds exhibit very strong NLO absorption in thin films and solution.

Two W/Cu/S clusters: tetraethylammonium bromidodi-μ2-sulfido-sulfido[tris(3,5-dimethylpyrazol-1-yl)borato]copper(I)tungsten(VI) and tetraethylammonium dibromido-μ3-sulfido-di-μ2-sulfido-[tris(3,5-dimethylpyrazol-1-yl)borato]dicopper(I)tungsten(VI)

The reaction of (Et(4)N)[Tp*WS(3)] [Tp* = hydrogen tris(3,5-dimethylpyrazol-1-yl)borate] with one or two equivalents of CuBr afforded the [1 + 1] and [1 + 2] addition products (Et(4)N)[Tp*WS(μ-S)(2)(CuBr)] {or (C(8)H(20)N)[CuWBr(C(15)H(22)BN(6))S(3)], (I)} and (Et(4)N)[Tp*W(μ(3)-S)(μ-S)(2)(CuBr)(2)] {or (C(8)H(20)N)[Cu(2)WBr(2)(C(15)H(22)BN(6))S(3)], (II)}. The anion of (I) contains a [W(μ-S)(2)Cu] core formed by the addition of one CuBr unit to the [Tp*WS(3)] species. The anion of (II) has a butterfly-shaped [W(μ(3)-S)(μ-S)(2)Cu(2)] core formed by the addition of two CuBr units to the [Tp*WS(3)] species. The [Tp*WS(3)] sections of each complex exhibit approximate C(3v) point symmetry and have closely comparable geometry. In (II), both the anion and cation lie on a crystallographic mirror plane. The structure of (I) is noncentrosymmetric and polar.