Tunable zinc benzamidinate complexes: coordination modes and catalytic activity in the ring-opening polymerization of L-lactide.

Seven asymmetric zinc benzamidinate complexes featuring or lacking side-arm functionalities were synthesized. Using equimolar zinc reagent produced distinct dinuclear motifs [(CH-C = NCH)ZnEt] (R = Bu, 1; (CH)OMe, 2; (CH)NMe, 3). Half the zinc reagent yielded dinuclear [(CH-C = NCH)Zn] (R = Bu, 4) or mononuclear zinc bis(chelate) complexes (R = (CH)OMe, 5; (CH)NMe, 6; CHPy, 7).

Aluminium complexes containing indolyl-phenolate ligands as catalysts for ring-opening polymerization of cyclic esters.

A family of aluminium complexes supported by mono-anionic indolyl-phenolate ligands are described. Reactions of indolyl-phenolate based ligand precursors, IndHPhOH, with 1.0 or 0.

Synthesis, Characterization, and Catalytic Application of Palladium Complexes Containing Indolyl-NNN-Type Ligands.

In this study, a series of -heterocyclic indolyl ligand precursors 2-Py-Py-IndH, 2-Py-Pz-IndH, 2-Py-7-Py-IndH, 2-Py-7-Pz-IndH, and 2-Ox-7-Py-IndH (LH-LH) were prepared. The treatment of ligand precursors with 1 equivalent of palladium acetate affords palladium complexes -. All ligand precursors and palladium complexes were characterized by NMR spectroscopy and elemental analysis.

Diverse Coordinative Zinc Complexes Containing Amido-Pyridinate Ligands: Structural and Catalytic Studies.

In this work, zinc complexes containing amidopyridinate ligands substituted with different pendant arms have been described. Treatment of ligand precursors with ZnEt at a 1:1 ratio in THF yields zinc ethyl complexes (PyN )(ZnEt) () and (PyN )(ZnEt) (), respectively. Complexes and show the same geometry as a distorted tetrahedron, but adopt different coordination behaviors supported by the ligands.

An unprecedented ZnO heteroadamantane cage containing anilido-pyridinate ligand and its activity for ring opening polymerization of l-lactide and ε-caprolactone.

(NPyCOMe)ZnEt(μ-O) (1) has been synthesized in situ by hydrolysis of ZnEt in a one pot process and it was proved by applying X-ray structure analysis that the organozinc anilido-pyridinate moiety encapsulated the zinc oxide cluster, which demonstrated one self-assembled coordinate mode "ZnO". Moreover, the catalytic activity was investigated and good activity for l-lactide and ε-caprolactone ring opening polymerization was observed with both living and controllable properties.

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.

Synthesis and catalytic application of magnesium complexes bearing pendant indolyl ligands.

Three novel indole-based ligand precursors [HIndPh(R), R = methoxy, HIndPh(OMe) (); thiomethoxy, HIndPh(SMe) (); and N,N'-dimethylamino, HIndPh(NMe2) ()] have been synthesized via Sonogashira and cyclization reactions with moderate to high yield. Reactions of these ligand precursors with 0.6 equivalent of Mg(n)Bu2 in THF afforded the magnesium bis-indolyl complexes , respectively.

Zinc complexes containing coumarin-derived anilido-aldimine ligands as catalysts for ring opening polymerization of L-lactide.

The coumarin-derived ligand precursors L(1)H-L(6)H have been prepared. Treatment of these ligand precursors with 1.2 equiv.

Calcium complexes containing oxalamidinate ligands as catalysts for ε-caprolactone polymerization.

A series of calcium complexes containing oxalamidinate ligands is described. Reactions of oxalamidinate ligand precursors, [PhN=C{NH(CH2)2OMe}-C{NH(CH2)2OMe}=NPh] (1), [PhN=C{NH(CH2)2NMe2}-C{NH(CH2)2NMe2}=NPh] (2), [Ph(TriMe)N=C{NH(CH2)2OMe}-C{NH(CH2)2OMe}=NPh(TriMe)] (3), [Ph(TriMe)N=C{NH(CH2)2SMe}-C{NH(CH2)2SMe}=NPh(TriMe)] (4), [Ph(TriMe)N=C{NHCH2Py}-C{NHCH2Py}=NPh(TriMe)] (5), with two molar equivalents of Ca[N(SiMe3)2]2(THF)2 gave calcium oxalamidinate complexes, [Ca{N(SiMe3)2}(THF)(PhN)C{N(CH2)2OMe}-]2 (6), [Ca{N(SiMe3)2}(THF)(PhN)C{N(CH2)2NMe2}-]2 (7), [Ca{N(SiMe3)2}(THF)(Ph(TriMe)N)C{N(CH2)2OMe}-]2 (8), [Ca{N(SiMe3)2}(THF)(Ph(TriMe)N)C{N(CH2)2SMe}-]2 (9), [Ca{N(SiMe3)2}(THF)(Ph(TriMe)N)C{NCH2Py}-]2 (10), respectively. The molecular structure of complex 7 was further characterized by the single crystal X-ray diffraction technique.

Palladacycles bearing tridentate CNS-type benzamidinate ligands as catalysts for cross-coupling reactions.

Three pendant benzamidines, [Ph-C(=NC(6)H(5))-{NH(E)}] [E = -(CH(2))(2)SMe (1); -(CH(2))(2)S(t)Bu (2); -o-C(6)H(4)SMe (3)], are described. Reactions of 1, 2 or 3 with one molar equivalent of Pd(OAc)(2) in CH(2)Cl(2) give the palladacyclic complexes, [Ph-C{-NH(η(1)-C(6)H(4))}{=N(E)}]Pd(OAc) [E = -(CH(2))(2)SMe (4); -(CH(2))(2)S(t)Bu (5); -o-C(6)H(4)SMe (6)], as mononuclear palladium complexes respectively. A minor product described as 5', {[Ph-C{-N(C(6)H(5))}{-N(CH(2))(2)S(t)Bu}]Pd(OAc)}(2), was isolated as benzamidinate-bridged dinuclear palladium complex upon recrystallizing from Et(2)O/hexane solution.

Structural and catalytic studies of zinc complexes containing amido-oxazolinate ligands.

Several zinc complexes bearing amido-oxazolinate ligands are described. Reactions of ligand precursors, HNC(2)(E)Oxa (HNC(2)(E)Oxa = HNC(2)(Me)Oxa, HNC(2)(OMe)Oxa, HNC(2)(StBu)Oxa and HNC(2)(NMe2)Oxa) or HNPh(SMe)Oxa, with half or one molar equivalent of ZnEt(2) afford bis(chelate) zinc complexes, (NC(2)(E)Oxa)(2)Zn [C(2)(E) = propyl, (1); C(2)(E) = 2-methoxyethyl, (2); C(2)(E) = 2-N,N'-dimethylethyl, (3)] or zinc ethyl complexes, (NC(2)(StBu)Oxa)ZnEt(4) and (NPh(SMe)Oxa)ZnEt(5), using tetrahydrofuran or hexane as solvents. The zinc benzyl oxide complexes, [(NC(2)(E)Oxa)Zn(μ-OBn)](2) [C(2)(E) = propyl, (6); C(2)(E) = 2-methoxyethyl, (7); C(2)(E) = 2-tert-butylthioethyl, (8)], are obtained from the reactions of ligand precursors, HNC(2)(E)Oxa, with one molar equivalent of ZnEt(OBn) (generated in situ on 1:1 ratio of ZnEt(2) and BnOH) in tetrahydrofuran.

Self-assembly from metal-organic vesicles to globular networks: metallogel-mediated phenylation of indole with phenyl boronic acid.

Self-assembly of the conformationally flexible bismethylimidazolyl ligands with Pd(OAc)(2) is described. Depending on whether the ligands provide the hydrogen bonding donor, a switching of metal-organic vesicles to globular networks gelating solvents is achieved. The metallogels exhibit catalytic activity for the cross-coupling of indole with phenyl boronic acid.

Ring-opening polymerization by lithium catalysts: an overview.

This critical review summarizes recent developments in the preparation and application of lithium catalysts/initiators such as, alkyl lithium, alkoxy lithium and bimetallic lithium compounds for ring-opening polymerization (ROP). The ROP of cyclic esters, cyclic carbonates, cyclo-silazanes, cyclo-silanes, cyclo-siloxanes, cyclo-carboxylate, cyclic phosphirene and quinodimethanes are covered in this review. The present paper emphasizes the polymerization kinetics and the control exhibited by the different types of lithium initiators/catalysts.

Synthesis and catalytic application of aluminium anilido-pyrazolate complexes.

A series of aluminium complexes containing anilido-pyrazolate ligands is described. Reactions of four anilido-pyrazolate ligand precursors, HNPhPz, HNPhTriMePz, HNPhOMePz, or HNPhSMePz [HNPhPz = ortho-C6H4(NH-phenyl)(1-pyrazole); HNPhTriMePz = ortho-C6H4(NH-2,4,6-trimethylphenyl)(1-pyrazole); HNPhOMePz = ortho-C6H4(NH-2-methoxyphenyl)(1-pyrazole); HNPhSMePz = ortho-C6H4(NH-2-methylthiophenyl)(1-pyrazole)], with one molar equivalent of AlMe3 in toluene give the aluminium dimethyl complexes, (NArPz)AlMe2 [Ar = phenyl, (NPhPz)AlMe2 (1); Ar = 2,4,6-trimethylphenyl, (NPhTriMePz)AlMe2 (2); Ar = 2-methoxyphenyl, (NPhOMePz)AlMe2 (3); Ar = 2-methylthiophenyl, (NPhSMePz)AlMe2 (4)], respectively. The molecular structures are reported for compounds 1 and 3.

Magnesium complexes containing bis-amido-oxazolinate ligands as efficient catalysts for ring opening polymerisation of L-lactide.

A series of magnesium bis(amido-oxazolinate) complexes have been described. Reactions of six amido-oxazolinate ligand precursors, HNC(2)(Me)Oxa, HNC(2)(OMe)Oxa, HNC(2)(StBu)Oxa, HNPhOxa, HNPh(OMe)Oxa or HNPh(SMe)Oxa, with half molar equivalent of Mg(n)Bu(2) in hexane yield the magnesium bis(amido-oxazolinate) complexes, (NC(2)(E)Oxa)(2)Mg [C(2)(E) = propyl, (NC(2)(Me)Oxa)(2)Mg (1); C(2)(E) = 2-methoxyethyl, (NC(2)(OMe)Oxa)(2)Mg (2); C(2)(E) = 2-tert-butylthioethyl, (NC(2)(StBu)Oxa)(2)Mg (3)], or magnesium bis(anilido-oxazolinate) complexes, (NArOxa)(2)Mg [Ar = phenyl, (NPhOxa)(2)Mg (4); Ar = 2-methoxyphenyl, (NPh(OMe)Oxa)(2)Mg (5); Ar = 2-methylthiophenyl, (NPh(SMe)Oxa)(2)Mg (6)], respectively. The molecular structures are reported for compounds 1, 2, 5 and 6.

Preferential formation of homochiral helical sandwich-shaped architectures through the metal-mediated assembly of tris(imidazoline) ligands with a set of d(3)-d(10) transition-metal ions.

A novel type of chiral tris-monodentate imidazolinyl ligands ((S,S,S)-4 and (R,R,R)-4) has been achieved in good yields. The ligands show a strong tendency to induce the generation of the discrete sandwich-shaped M(3)L(2) architectures with programmed helicity through the edge-directed complexation with a series of d(3)-d(10) transition-metal ions, while taking advantage of the steric hindrance of the bulky substituents of the imidazoline rings to avoid the formation of extended metal-organic frameworks (MOFs). In spite of different coordination geometries, monovalent metal ions (e.

Structural and catalytic studies of lithium complexes bearing pendant aminophenolate ligands.

Lithium complexes bearing mono-anionic aminophenolate ligands are described. Reactions of ligand precursors HON(Me)Ph(OMe), HON(Me)Ph(SMe), HON(Me)C(OMe) or HON(Me)C(NMe2) [HON(Me)Ph(OMe) = (2-OMeC6H4CH2)N(Me)(CH2-2-HO-3,5-C6H2((t)Bu)2); HON(Me)Ph(SMe)= (2-SMe-C6H4CH2)N(Me)(CH2-2-HO-3,5-C6H2((t)Bu)2); HON(Me)C(OMe) = (MeOCH(2)CH2)N(Me)(CH2-2-HO-3,5-C6H2((t)Bu)2); HON(Me)C(NMe2) = (Me2NCH2CH2)N(Me)(CH2-2-HO-3,5-C6H2((t)Bu)2)] with 1.1-1.

Lithium complexes supported by amine bis-phenolate ligands as efficient catalysts for ring-opening polymerization of L-lactide.

Lithium complexes bearing dianionic amine bis(phenolate) ligands are described. Reactions of ligand precursors H(2)O(2)NN(Me), H(2)O(2)NN(Py) or H(2)O(2)NO(Me) [H(2)O(2)NN(Me)=Me(2)NCH(2)CH(2)N-(CH(2)-2-HO-3,5-C(6)H(2)((t)Bu)(2))(2); H(2)O(2)NN(Py)=(2-C(5)H(4)N)CH(2)N-(CH(2)-2-HO-3,5-C(6)H(2)((t)Bu)(2))(2); H(2)O(2)NO(Me)=MeOCH(2)CH(2)N-(CH(2)-2-HO-3,5-C(6)H(2)((t)Bu)(2))(2)] with 2.2 molar equivalents of (n)BuLi in diethylether afford (Li(2)O(2)NN(Me))(2) (1), (Li(2)O(2)NN(Py))(2) (2) and (Li(2)O(2)NO(Me))(2) (3) as tetra-nuclear lithium complexes.

Zinc anilido-oxazolinate complexes as initiators for ring opening polymerization.

Three new anilido-oxazolines, ortho-C(6)H(4)(NHAr')(4,4-dimethyl-2-oxazoline) [Ar'=2,4,6-trimethylphenyl, HNPh(TriMe)Oxa (1); 2,6-diisopropylphenyl, HNPh(DiiPr)Oxa (2); 2-methoxyphenyl, HNPh(OMe)Oxa (3)], have been prepared. Reactions of 1 or 2 with one molar equivalent of ZnEt(2) in tetrahydrofuran or hexane solution give the zinc ethyl complexes (NPh(TriMe)Oxa)ZnEt (4) and (NPh(DiiPr)Oxa)ZnEt (5). The dinuclear zinc benzyloxide complexes, [(NAr'Oxa)Zn(mu-OBn)](2), [Ar'=2,4,6-trimethylphenyl, (6); 2-methoxyphenyl, (7)], were synthesized by the reaction of 4 with one molar equivalent of benzyl alcohol in tetrahydrofuran solution (for 6) or by treatment of with 3 one molar equivalent of ZnEt(2) in tetrahydrofuran solution followed by the addition of one molar equivalent of benzyl alcohol (for 7).

Electrophoresis of a rigid sphere in a Carreau fluid normal to a planar surface.

The boundary effect on electrophoresis is investigated by considering the electrophoresis of a spherical particle in a non-Newtonian fluid normal to a planar surface under conditions of low surface potential and weak applied electric field. The Carreau model, which is widely used for the description of polymeric fluids of shear-thinning nature, is adopted to simulate the non-Newtonian behavior of the fluid. We show that, in general, shear thinning has the effect of raising the electrophoretic mobility of a particle.

Palladacyclic complexes bearing CNN-type ligands as catalysts in the Heck reaction.

Preparations of novel unsymmetrical, tridentate nitrogen ligand precursors, PhN=C(CMe2)(NPh)C=N(CH2)2NMe2(1) and PhN=C(CMe2)(NPh)C=N(CH2)Py (2), are described. Treatment of 1 with 1 molar equiv. (COD)PdCl2 in the presence of NEt3 or with 1 molar equiv.