Preparation and structures of 6- and 7-coordinate salen-type zirconium complexes and their catalytic properties for oligomerization of ethylene

A series of salen-type zirconium complexes of the general formula LZrCl₂ (L = N,N′-ethylenebis(salicylideneiminate), 3a; N,N′-ethylenebis(3,5-di-tert-butylsalicylideneiminate), 3b; N,N′-ethylenebis(5-methoxysalicylideneiminate), 3c; N,N′-ethylenebis(5-chlorosalicylideneiminate), 3d; N,N′-ethylenebis(5-nitrosalicylideneiminate), 3e; N,N′-o-phenylenebis(salicylideneiminate), 4a; N,N′-o-phenylenebis(3,5-di-tert-butylsalicylideneiminate), 4b; N,N′-o-phenylenebis(5-methoxysalicylideneiminate), 4c; N,N′-o-phenylenebis(5-chloro-salicylideneiminate), 4d) were prepared. The crystal structures of 6- and 7-coordinate zirconium complexes 4b and [4b · OCMe₂] were determined by X-ray crystallography, which reveals that a salen-type zirconium complex possesses a labile coordination site on the Zr center with a relatively stable framework and that the coordination and the dissociation of O-donor molecules occur readily at this site. The catalytic properties of 3(a-e) and 4(a-d) were studied for ethylene oligomerization in combination with Et₂AlCl as co-catalyst. Complex 3c featuring a methoxy-substituted salen ligand displayed higher activity than its analogous precursors having chloro and nitro groups as substituents. The catalytic reactions by 3(a-e) and 4(a-d) gave C₄-C₁₀ olefins and low-carbon linear α-olefins in good selectivity.     

Crystal structures and certain properties of hapnium-beryllium compounds

Summary The system Hf-Be was investigated by x-ray structural and microstructural analysis and by determinations of microhardness. The existence of four compounds was established: {ie402-1}Translated from Zhurnal Strukturnol Khimil, Vol. 2, No. 4, pp. 424–433, July–August 1961     

Titanium(IV) complexes with monocyclopentadienyl and phenoxy-alkoxo ligands: Synthesis,structures and catalytic properties for ethylene polymerization

Three monochlorotitanium complexes Cp′Ti(2,4-^tBu₂-6-(CPh₂O)C₆H₂O)Cl [Cp′ = η⁵-C₅H₅ (2), η⁵-C₅(CH₃)₅ (3), η⁵-C₅H₂Ph₂CH₃ (4)] have been synthesized in high yields (>90%) by the reaction of corresponding Cp′TiCl₃ with the dilithium salt of ligand 2,4-^tBu₂-6-(CPh₂OH)C₆H₂OH (1). When activated by [Ph₃C]⁺[B(C₆F₅)₄]⁻ and AlⁱBu₃, complexes 2–4 exhibit reasonable catalytic activity for ethylene polymerization, producing polyethylenes with moderate molecular weights and melting points. Addition of excess water to complex 2 gave the oxo-bridged complex [Ti(η⁵-C₅H₅)(2,4-^tBu₂-6-(CPh₂O)C₆H₂O)]₂O (5). Complexes 4 and 5 were characterized by single crystal X-ray diffraction.     

Titanium and zirconium complexes with aminoiminophosphorane ligands

A series of titanium and zirconium complexes based on aminoiminophosphorane ligands [Ph₂P(Nt‐Bu)(NR)]₂MCl₂ ( 4 , M = Ti, R = Ph; 5 , M = Zr, R = Ph; 6 , M = Ti, R = SiMe₃; 7 , M = Zr, R = SiMe₃) have been synthesized by the reaction of the ligands with TiCl₄ and ZrCl₄. The structure of complex 4 has been determined by X‐ray crystallography. The observed very weak interaction between Ti and P suggests partial π‐electron delocalization through both Ti and P. The complexes 4–7 are inactive for ethylene polymerization in the presence of modified methylaluminoxane (MMAO) or i‐Bu₃Al–Ph₃CB(C₆F₅)₄ under atmospheric pressure, and is probably the result of low monomer ethylene concentration and steric congestion around the central metal. Copyright © 2005 John Wiley & Sons, Ltd.     

Syntheses and structures of non-symmetric guanidinato zirconium and hafnium complexes and their catalytic behavior for ethylene polymerization

Equivalent addition reactions of PhN(Li)SiMe₃ to nitriles, RCN (R = dimethylamido, 1-piperidino), generated non-symmetric guanidinato lithium [(Et₂O)LiN(SiMe₃)C(NMe₂)N(Ph)]₂ (1) or [(THF)LiN(SiMe₃)C(NMe₂)N(Ph)]₂ (2) and [(Et₂O)LiN(SiMe₃)C(N(CH₂)₅)N(Ph)]₂ (5) which further reacted with zirconium or hafnium tetrachloride to form Zr and Hf guanidinato complexes with the general formula [PhNC(R)NSiMe₃]₃MCl (R = dimethylamido, M = Zr (3), Hf (4); R = 1-piperidino, M = Zr (6), Hf (7)). Complexes 1-4, 6 and 7 were well characterized by ¹H, ¹³C NMR and microanalysis, the single crystal X-ray diffraction analysis data for complexes 1, 3, 4 and 7 were also provided. Furthermore, complexes 3, 4, 6 and 7 were found to be active for ethylene polymerization. The influences of cocatalyst, pressure, reaction temperature and Al/M ratio on activity were investigated.     

Titanium and zirconium complexes supported by dipyrrolide ligands

The reactions between meso-disubstituted dipyrromethanes and titanium and zirconium amides and alkyls have generated the first examples of dipyrrolide complexes of Group 4 metals.     

Titanium and zirconium complexes with novel phenoxy-phosphinimine ligands

A series of novel phenoxy-phosphinimine ligands (L): L = 2-(Ph₂PNR), 4, 6-(CMe₃)₂-C₆H₂OH [2, R = SiMe₃; 3, R = Ph] have been prepared in the yield of 65-71%. And bis(phenoxy-phosphinimide) group 4 complexes of the type L₂MCl₂ [4, M = Ti, R = SiMe₃; 5, M = Zr, R = SiMe₃; 6, M = Ti, R = Ph; 7, M = Zr, R = Ph] have been synthesized by the reaction of the ligands with TiCl₄ and ZrCl₄. The structure of complex 7 has been determined by X-ray crystallography. The complexes 4-7 showed inactive to ethylene polymerization in the presence of modified methylaluminoxane (MMAO) and i-Bu₃Al/Ph₃CB(C₆ F₅)₄. These results should be caused by overdoing the steric congestion around central metal.     

The electron acceptor and catalytic properties of zirconium dioxide modified with aluminum and gallium oxides

The electron acceptor properties of the mixed oxide systems 20 mol % M₂O₃-ZrO₂ (M = Al, Ga) and 10 mol % M₂O₃-10 mol % Al₂O₃-ZrO₂ (M = Ga, Y) were studied by recording the EPR spectra of paramagnetic complexes of adsorbed anthraquinone. The EPR data were compared with the catalytic activity of the mixed oxides in the decomposition of propanols and butanols in a pulsed microcatalytic reactor. The Al₂O₃-ZrO₂ and Ga₂O₃-ZrO₂ solid solutions were found to be metastable and decompose as the temperature of calcining increased or a third component was introduced. Correspondence between the EPR data and catalytic experiment results was established. This correspondence substantiates the occurrence of the segregation of the Al₂O₃ and Ga₂O₃ amorphous phases on the surface of zirconia, which accompanies the decay of the M₂O₃-ZrO₂ (M = Al, Ga) metastable solid solutions. The Al₂O₃-ZrO₂ solid solution decomposes more readily than Ga₂O₃-ZrO₂.     

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.     

Titanium and zirconium complexes of preorganized tripodal triaryloxide ligands

Tri(2-oxy-3,5-di-tert-butylphenyl)methane, [O3]3- has been used to prepare titanium and zirconium complexes of the general formula [O3]MX (M = Ti, X = NEt2, Cl, CH2Ph; M = Zr, X = CH2Ph). The tripodal [O3] ligand in titanium complexes adopt the syn- and the anti-conformation, while the syn complex of zirconium undergoes facile C-H activation to give a 5-carbametalatrane [O3C]Zr(THF)3.     

Crystal structures of crown and aza-crown ether complexes with zirconium,hafnium, niobium,and tantalum fluorometallates

A systematic X-ray diffraction study of the interaction products of Zr(IV), Hf(IV), Nb(V), and Ta(V) oxides (fluorides) with crown-ethers (CEs) in aqueous solutions of hydrofluoric acid is performed. It is shown that oxygen-containing CEs form oxonium complexes with [NbF6]^s- and [TaF6]^s- hexafluorometallate anions. In two systems, [cis-syn-cis-DCH18C6-H₃O][TaF₆] and [B18C6·H₃O][TaF₆], the phenomenon of supramolecular isomerism is found, which is caused by a change in the conformation of the macrocycle or by a partial redistribution of intermolecular hydrogen bonds. The use of aza-crown ethers as extractants made it possible to extract unique hydrolytically unstable anions, the products of incomplete fluorine substitution for oxygen atoms in the starting oxides in the form of crystalline complexes with a composition of [(HA15C5)₂][Ta₂F₁₀O] and [(HA18C6·H₂O)(A18C6·H₂O)] [(H₂O)Nb₂F₉O]. In [(18C6)(H₇O₃)₂×(Hf₂F₁₀·2H₂O)], [(HA18C6)(M₂F₁₀·2H₂O)·(H₃O)·H₂O], and [(H₂DA18C6) (M₂F₁₀·2H₂O)·2H₂O] (M=Zr, Hf) complexes, the metals are extracted in the form of identical (M₂F₁₀·2H₂O)^2s- anions with a similar topology. The performed study demonstrates that macrocyclic complexones are undoubtedly promising to extract Zr(IV), Hf(IV), Nb(V), and Ta(V) from fluorine-containing aqueous solutions.     

Synthesis and structures of zirconium amide-iodide complexes

Zirconium amide-iodide complexes were synthesized for possible use as chemical vapor deposition precursors to zirconium nitride films. The series of six complexes Zr(NR(2))(4-n)I(n)(R = Me or Et; n = 1-3) was prepared by reacting ZrI(4) and Zr(NR(2))(4) in hot toluene. X-ray crystallographic analyses were performed for Zr(NMe(2))(3)I, Zr(NEt(2))(2)I(2), and Zr(NEt(2))I(3). In the solid state, Zr(NMe(2))(3)I and Zr(NEt(2))(2)I(2) are the discrete dimers [Zr(NMe(2))(2)I(mu-NMe(2))](2) and [Zr(NEt(2))(2)I(mu-I)](2), and Zr(NEt(2))I(3) is the polymer of dimers ([Zr(NEt(2))I(2)(mu-I)](2))(n). In solution, Zr(NEt(2))(3)I is proposed to be monomeric on the basis of NMR data and a molecular weight determination. The complex Zr(NEt(2))(3)I is the most promising precursor candidate because of its physical properties.     

Layered zirconium phosphate-supported metalloporphyrin： Synthesis and catalytic application

This paper reports a new route for the preparation of layered alpha-zirconium phosphate （α-ZrP）-supported metalloporphyrin MnTMPyP. MnTMPyP was intercalated into α-ZrP using α-ZrP.BA （i.e. pre-intercalated bultylamine was arranged by a monolayer mode in α-ZrP） as a starting material. The catalytic activity of the supported material for homovanillic acid （HVA） oxidation was investigated. The results showed a promising layered material-supported catalyst in catalytic system.