Mono- and dinuclear copper complexes coordinated on NNO-tridentate Schiff-base derivatives for copolymerization of cyclohexene oxide and cyclic anhydrides.

A series of bimetallic penta-coordinated copper complexes [LCu(OAc)] (1, 3-7), a mononuclear tetra-coordinated copper complex [LCu(OAc)] (8 and 9), and a penta-coordinated copper complex [LCu(OAc)(HO)] (10) were prepared by the reaction of Cu(OAc)·HO with a variety of NNO-tridentate Schiff-base ligands (L-H-L-H) in refluxing 95% ethanol, respectively. However, a dinuclear copper complex [(L)Cu(OAc)] (2) can be obtained from the treatment of L-H with a stoichiometric amount of anhydrous Cu(OAc) in refluxing absolute EtOH under a dry nitrogen atmosphere. All of these copper complexes are active for the alternating copolymerization of cyclohexene oxide and cyclic anhydride, affording polyesters with moderate polydispersity.

Metal complexes containing nitrogen-heterocycle based aryloxide or arylamido derivatives as discrete catalysts for ring-opening polymerization of cyclic esters.

The development of well-defined homogeneous catalysts for the ring-opening polymerization (ROP) of cyclic esters has made enormous progress over the past decade. This perspective focuses on some recent advances in the field of discrete metal complexes modified by various aryloxide or arylamido ligands bearing the nitrogen-containing heterocycle moiety, and their catalytic applications in ROP of lactones. It mainly highlights aryloxide/arylamido ligands that are directly installed by the N-heterocyclic group.

Dinuclear and Trinuclear Nickel Complexes as Effective Catalysts for Alternating Copolymerization on Carbon Dioxide and Cyclohexene Oxide.

A series of novel nickel complexes 1-9 supported by NNO-tridentate Schiff-base derivatives have been synthesized and characterized. Treatment of the pro-ligands [L(1)-H = 2,4-di-tert-butyl-6-(((2-(dimethylamino)ethyl)imino)methyl)phenol, L(2)-H = 2-(((2-(dimethylamino)ethyl)imino)methyl)-4,6-bis(2-phenylpropan-2-yl)phenol, L(3)-H = 2-(((2-(dimethylamino)ethyl)imino)methyl)phenol] with Ni(OAc)2·4H2O in refluxing ethanol afforded mono- or bimetallic nickel complexes {[(L(1))Ni(OAc)] (1); (L(2))Ni(OAc)] (2); (L(3))2Ni2(OAc)2(H2O)] (3)}. Alcohol-solvated trimetallic nickel acetate complexes {[(L(3))2Ni3(OAc)4(MeOH)2] (4); (L(3))2Ni3(OAc)4(EtOH)2] (5)} could be generated from the reaction of L(3)-H and anhydrous nickel(II) acetate with a ratio of 2:3 in refluxing anhydrous MeOH or EtOH.

Synthesis of Sodium Complexes Supported with NNO-Tridentate Schiff Base Ligands and Their Applications in the Ring-Opening Polymerization of L-Lactide.

A series of sodium complexes bearing NNO-tridentate Schiff base ligands with an N-pendant arm were synthesized and used as catalysts for the ring-opening polymerization of L-lactide (L-LA). Electronic effects of ancillary ligands coordinated by sodium complexes substantially influence the catalysis, and ligands with electron-donating groups increase the catalytic activity of the sodium complexes for catalyzing L-LA polymerization. In particular, a sodium complex bearing a 4-methoxy group has the highest activity with conversion up to 95% within 30 s at 0 °C and a low polydispersity index of 1.

Mono-, di- and tetra-zinc complexes derived from an amino-benzotriazole phenolate ligand containing a bulkier N-alkyl pendant arm: synthesis, structure and catalysis for ring-opening polymerization of cyclic esters.

Zinc complexes constructed from the amino-modified benzotriazole phenol pro-ligand, 2-(2H-benzotriazol-2-yl)-6-((diisopropylamino)methyl)-4-(2,4,4-trimethylpentan-2-yl)phenol ((C8DIA)BTP-H, 1), were synthesized stepwise and structurally characterized. The reaction of (C8DIA)BTP-H (1) with one equivalent of diethyl zinc (ZnEt2) generates a dimeric and four-coordinated zinc complex, [(μ-(C8DIA)BTP)ZnEt]2 (2), which is doubly bridged by two phenolate groups of C8DIABTP ligands. Further reaction of 2 with benzyl alcohol (BnOH) in stoichiometric proportions affords a tetranuclear zinc benzylalkoxide complex [(μ-OBn)((C8DIA)BTP)Zn]4 (3) that possesses a saddle-shaped core with four μ2-bridging benzylalkoxy groups upon four Zn centres.

Structurally diverse copper complexes bearing NNO-tridentate Schiff-base derivatives as efficient catalysts for copolymerization of carbon dioxide and cyclohexene oxide.

Structurally diverse copper acetate complexes based on NNO-tridentate Schiff-base ligands were synthesized and characterized as mono-, di-, and trinuclear complexes with respect to varied ancillary ligands. Treatment of the ligand precursors (L(1)-H = 2-(1-((2-(dimethylamino)ethyl)imino)ethyl)-4-methylphenol, L(2)-H = 4-chloro-2-(1-((2-(dimethylamino)ethyl)imino)ethyl)phenol, and L(3)-H = 2-(1-((2-(dimethylamino)ethyl)imino)ethyl)-5-methylphenol) with Cu(OAc)2·H2O (1 equiv) in refluxing ethanol afforded five-coordinate mono- or bimetallic copper complexes ([(L(1))Cu(OAc)(H2O)] (1); [(L(2))Cu(OAc)(H2O)] (2); [(L(3))2Cu2(OAc)2] (3)) in high yields. Dinuclear copper acetate analogue [(L(1))2Cu2(OAc)2] (4) resulted from treatment of L(1)-H as the ligand precursor in refluxing anhydrous MeOH with equimolar proportions of metal acetate salt under a dry nitrogen atmosphere.

Synthesis and structural determination of zinc complexes based on an anilido-aldimine ligand containing an O-donor pendant arm: zinc alkoxide derivative as an efficient initiator for ring-opening polymerization of cyclic esters.

Zinc complexes bearing the anilido-aldiminate AA(OMe) ligand (AA(OMe)-H = (E)-2,6-diisopropyl-N-(2-(((2-methoxyethyl)imino)methyl)phenyl)aniline) were synthesized in a stepwise method and were structurally characterized. The reaction of AA(OMe)-H (1) with one equivalent of diethyl zinc (ZnEt2) furnishes a three-coordinated and mononuclear zinc complex [(AA(OMe))ZnEt] (2). Further reaction of 2 with a stoichiometric amount of benzyl alcohol (BnOH) affords a four-coordinated and dinuclear zinc benzylalkoxide complex [(AA(OMe))Zn(μ-OBn)]2 (3).

5-(Diphenyl-methyl-idene)pyrrolidin-2-one.

In the title compound, C(17)H(15)NO, the dihedral angle between the phenyl rings is 80.1 (2)°. In the crystal, mol-ecules are linked by pairs of N-H⋯O hydrogen bonds, forming inversion dimers.

Methyl 2-[(tert-but-oxy-carbon-yl)amino]-3-(3-methyl-2-sulfanyl-idene-2,3-dihydro-1H-imidazol-1-yl)propano-ate.

In the title compound, C(13)H(21)N(3)O(4)S, the mean plane of the -N(H)-C(=O)-O- group of the carbamate unit forms a dihedral angle of 64.7 (2)° with the mean plane of the -C-C(=O)-O- group of the ester unit. In the crystal, mol-ecules are linked by N-H⋯O=C hydrogen bonds, forming chains along the c-axis direction.

tert-Butyl 2-sulfanylidene-2,3-dihydro-1H-imidazole-1-carboxyl-ate.

In the title mol-ecule, C(8)H(12)N(2)O(2)S, the imidazole ring forms a dihedral angle of 5.9 (2)° with the mean plane of the carboxyl-ate group. In the crystal, mol-ecules are linked by pairs of N-H⋯S hydrogen bonds, forming inversion dimers.

Bis{1-[(E)-(2-methyl-phen-yl)diazen-yl]-2-naphtho-lato}palladium(II).

In the title compound, [Pd(C(17)H(13)N(2)O)(2)], the Pd(II) atom is tetra-coordinated by two N atoms and two O atoms from two bidentate methylphenyl-diazenylnaphtolate ligands, forming a square-planar complex. The two N atoms and two O atoms around the Pd(II) atom are trans to each other (as the Pd(II) atom lies on a crystallographic inversion centre) with O-Pd-N bond angles of 89.60 (11) and 90.

Synthesis, characterization, and structural determination of polynuclear lithium aggregates and factors affecting their aggregation.

The reaction of [(mu3,mu3-EDBP)Li2]2[(mu3-nBu)Li(0.5Et2O)]2 (1) [EDBP-H2 = 2,2'-ethylidenebis(4,6-di-tert-butylphenol)] with 1 equiv of ROH in toluene gave [(mu3,mu3-EDBP)Li2]2[(mu3-OR)Li]2 [R = Bn (2), CH2CH2OEt (3), and nBu (4)]. In the presence of 3 equiv of tetrahydrofuran (THF), the hexanuclear compound 1 slowly decomposed to an unusual pentanuclear Li complex, [(mu2,mu3-EDBP)2Li4(THF)2][(mu3-nBu)Li] (5).

Reactions of amides with organoaluminum compounds: factors affecting the coordination mode of aluminum amidates.

Factors affecting the coordination mode of an amidato group on aluminum will be presented. The reaction of N-tert-butylalkylacetamide ((t)BuNHCR([double bond]O)) with 1.1 molar equiv of Me(3)Al in refluxing hexane affords a pentacoordinated, dimeric compound [Me(2)Al[eta(2)-(t)BuNC(R)(mu(2)-O)]](2) (3, R = p-(t)Bu-C(6)H(4); 4, R = 2,6-F,F-C(6)H(3); 5, R = Me; 6, R = CF(3); 7, R = p-F(3)C-C(6)H(4)).