(η3-Azaallyl)zirconium Chlorides: Synthesis, Characterization, and Ethylene (Co-)polymerization Activity

Crystal structure of a zwitterionic azaallyl zirconiumamide complex bearing a Zr+-μ-CH3—B− moiety and one equivalent of n-hexane as a solvent

The zirconiumamide complex [(cyclohex-1-enyl)cyclohexylamido]bis(dicyclohexylamido)[methyltris(pentafluorophenyl)borato]zirconium(IV) hexane monosolvate, [Zr{N(C6H11)2}2{N(C6H11)(C6H9)}{BCH3(C6F5)3}]·C6H14, is zwitterionic and bears a Zr+—μ-CH3—B− moiety. The reaction of tris(dicyclohexylamido)methylzirconium with the strong Lewis acid tris(pentafluorophenyl)borane results in the formation of an azaallyl zirconium motif by the loss of H2 in one dicyclohexylamido ligand, as shown by single-crystal X-ray diffraction. The ZrIV cation is coordinated to the N atoms of two dicyclohexylamido ligands, the π-system of one azaallyl ligand, and to the μ-CH3—B unit, resulting in a distorted tetrahedral coordination environment. The Zr—N distance to the azaallyl ligand is elongated, whereas the Zr—C distance to this moiety is found to be shortened in comparison with those to the two Cy2N groups (Cy is C6H11).

Azasilicon-bridged heterocyclic arylamines: syntheses, structures and photophysical properties

The lithium κ¹-enamides undergo intermolecular cyclization reactions affording bis-azasilicon-bridged heterocyclic arylamines, which were hydrolysed to the saturated 1,4-diimines, and alternatively proceeded a redox reaction to afford the conjugated 1,4-diimines.

Zirconium complexes based on an ethylene linked amidinate–amido ligand: synthesis, characterization and ethylene polymerization

Monomer/dimer zirconium complexes 4–6 were synthesized by changing the molar ratio of ZrCl4 : ligand. The catalytic behaviors of these zirconium complexes were investigated in the presence of MAO as a cocatalys.

Arylimido zirconium and titanium complexes: characteristic structures and application in ethylene polymerization

Dimeric anilidolithium (ArHNLi·Et2O)2 (Ar=2,6- i Pr2C6H3) reacted with zirconium tetrachloride in THF to give the heterometallic zirconium–lithium complex [(Et2O)2Li(μ-Cl)2(ArHN)(ArN=)Zr(μ-Cl)]2 (C1) and with titanium tetrachloride in toluene to give the titanium complex [(ArN=)TiCl2·(Et2O)2] (C2) each in good isolated yields. Their molecular structures in the solid state were confirmed by X-ray diffraction analysis. Upon activation with methylaluminoxane, both arylimido zirconium and titanium complexes exhibited good catalytic activities toward ethylene polymerization.

Salt metathesis versus protonolysis routes for the synthesis of silylamide Hauser base (R2NMgX; X = halogen) and amido-Grignard (R2NMgR) complexes

The preparation of silylamide Hauser base (R2NMgX; X = halide) and amido-Grignard (R2NMgR) complexes from simple Grignard reagents using [K{N(SiMe2(t)Bu)2}]n, [K{N(SiMe2(t)Bu)(Si(i)Pr3)}]n and [K{N(Si(i)Pr3)2}]n, and their parent silylamines, was explored. Both salt metathesis and protonolysis routes proved ineffective with allylmagnesium chloride as a starting material due to complex Schlenk equilibria, with [Mg(N(RR'))(μ-Cl)(THF)]2 (N(RR') = {N(Si(t)BuMe2)2}(-), 1; {N(Si(t)BuMe2)(Si(i)Pr3)}(-), 2; {N(Si(i)Pr3)2}(-), 3) and [Mg{N(Si(i)Pr3)2}(μ-C3H5)]∞ (4) identified as minor products. In contrast, salt metathesis protocols using potassium silylamides and methylmagnesium iodide gave [Mg(N(RR'))(μ-CH3)]2 (N(RR') = {N(Si(t)BuMe2)2}(-), 7a; {N(Si(t)BuMe2)(Si(i)Pr3)}(-), 8; {N(Si(i)Pr3)2}(-), 9) and [Mg{N(Si(t)BuMe2)2}(CH3)(DME)] (7b), with [Mg{N(Si(t)BuMe2)2}(μ-I)(THF)]2 (10) isolated as a side-product during the preparation of 7a. Unusually, methylmagnesium iodide, di-n-butylmagnesium and 7-9 did not react with HN(RR') under the conditions we employed. The synthesis of [Na{N(Si(t)BuMe2)2}(THF)]2 (5a) and [Na{N(Si(t)BuMe2)2}(DME)2] (5b) from benzyl sodium and HN(Si(t)BuMe2)2, and a solvent-free structure of [K{N(Si(t)BuMe2)2}] (6), are also reported. Complexes 1, 5b, 7a, 7b, 8, 9 and 10 are fully characterised by single crystal XRD, multinuclear NMR and IR spectroscopy and elemental analysis, whereas complexes 2-4, 5a and 6 were identified by XRD only.

Group IV compounds bearing a novel tridentate N-donor ligand: synthesis, structures and ethylene polymerization

In this paper, treatment of [PhN(CH₂)₃NC(Ph)NSiMe₃]₂Li₄·2Et₂O with group IV metal chlorides yields corresponding compounds 3–5. The catalytic behaviors of 3–5 were investigated in the presence of MAO as co-catalyst for ethylene polymerization.

Metal (Mg, Fe, Co, Zr and Ti) complexes derived from aminosilyl substituted aminopyridinato ligand: synthesis, structures and ethylene polymerization behaviors of the group 4 complexes

Lithium N-[(N,N-dimethylamino)dimethylsilyl]-2-pyridylamidate (2) was prepared from the reaction of new compound N-[(N,N-dimethylamino)dimethylsilyl]-2-pyridylamine (1) and LiBu(n). Treatment of the lithium salt (2) with an equal equivalent of MgBr(2)(THF)(2), FeCl(2) and CoCl(2) afforded the corresponding dinuclear complexes , , and , in which metal atoms possess similar trigonal bipyramidal geometries and each ligand functions as a bimetallic bridging binding aminopyridinato moiety with N-donation from the dimethylamino group. While the stoichiometric reaction of with ZrCl(4) gave the mononuclear zirconium complex (6); the seven coordinated zirconium atom adopts a distorted pentagonal bipyramid geometry and the ligand acts as monoanionic η(2)-aminopyridinato moiety with the pendant arm coordinated via N(CH(3))(2). The reaction of with one equivalent of TiCl(4)(THF)(2) produced the interesting dinuclear titanium complex (7) owing to the elimination of a (N,N-dimethylamino)dimethylsilyl group from the original ligand, and the two titanium centers present different coordination geometries. The molecular structures of the crystalline metal complexes have been confirmed by X-ray single crystal diffraction analysis. Upon activation with methylaluminoxane (MAO), both complexes and exhibited moderate catalytic activities toward ethylene polymerization and produced high molecular weight polyethylenes with broad molecular weight distributions.

Synthesis, characterization, and catalytic properties of new half-sandwich zirconium(IV) complexes

A number of new half-sandwich zirconium(IV) complexes bearing N,N-dimethylaniline-amido ligands with the general formula Cp*ZrCl(2)[ortho-(RNCH(2))(Me(2)N)C(6)H(4)] [R = 2,6-Me(2)C(6)H(3) (1), 2,6-(i)Pr(2)C(6)H(3) (2), (i)Pr (3), (t)Bu (4)] were synthesized by the reaction of Cp*ZrCl(3) with the corresponding ortho-(Me(2)N)C(6)H(4)CH(2)NRLi. All new zirconium complexes were characterized by (1)H and (13)C NMR, elemental analyses and single crystal X-ray diffraction analysis. The molecular structural analysis reveals that the NMe(2) group does not coordinate to the zirconium atom in all cases. Complexes 1-4 all have a pseudo-tetrahedral coordination environment in their solid state structures and adopt a three-legged piano stool geometry for the zirconium atoms with the amide N atom and the two Cl atoms being the three legs and the Cp* ring being the seat. Variable-temperature (1)H NMR experiments for all complexes 1-4 were performed to investigate the possible intramolecular interaction between the N atom in the NMe(2) group and the central zirconium atom in solution. Upon activation with Al(i)Bu(3) and Ph(3)CB(C(6)F(5))(4), complexes 1-4 all exhibit moderate to good catalytic activity for ethylene polymerization and copolymerization with 1-hexene, producing linear polyethylene or poly(ethylene-co-1-hexene) with moderate molecular weight and reasonable 1-hexene incorporation.