Nickel(II) and copper(II) complexes containing 2-(2-(5-substitued isoxazol-3-yl)hydrazono)-5,5-dimethylcyclohexane-1,3-dione ligands: Synthesis, spectral and thermal characterizations

Two new hydrazone chelating ligands, 2-(2-(5-methylisoxazol-3-yl)hydrazono)-5,5-dimethylcyclohexane-1,3-dione (HL1) and 2-(2-(5-tert-butylisoxazol-3-yl)hydrazono)-5,5-dimethylcyclohexane- 1,3-dione (HL2), and their nickel(II) and copper(II) complexes were synthesized using the procedure of diazotization, coupling and metallization. Their structures were postulated based on elemental analysis, H-1 NMR, ESI-MS, FT-IR spectra and UV-vis electronic absorption spectra. Smooth films of these complexes on K9 glass substrates were prepared using spin-coating and their absorption properties were evaluated. The thermal properties of the metal(II) complexes were investigated by thermogravimetry (TG) and differential thermogravimetry (DTG). Different thermodynamic and kinetic parameters namely activation energy (E

Metal dependent control of cis-/trans-1,4 regioselectivity in 1,3-butadiene polymerization catalyzed by transition metal complexes supported by 2,6-bis[1-(iminophenyl)ethyl]pyridine

Fe(III), Cr(III), Fe(II), Co(II) and Ni(II) chloride complexes supported by 2,6-bis[1-(iminophenyl)ethyl]pyridine have been synthesized and characterized along with single crystal X-ray diffraction. These complexes, in combination with MAO, have been examined in butadiene polymerization. The catalytic activity and regioselectivity are strongly controlled by metal center and cocatalyst (MAO/Co ratio dependent in the case of Co(II) complex). The activity decreases in the order of Fe(III) > Co(II) > Cr(III) approximate to Ni (II) complexes, in consistent with the space around the metal center. Polybutadiene with different microstructure content, from high trans-1,4 units (88-95% for iron(III) and Cr(III)), medium trans-1,4 and cis-1,4 units (55% and 35%, respectively, for iron(II)) to high cis-1,4 units 79% for Co(II) and 97% for Ni(II) call be easily achieved by varying of the metal center.

Rare-earth-metal mixed hydride/aryloxide complexes bearing mono(cyclopentadienyl) ligands. Synthesis, CO2 fixation, and catalysis on copolymerization of CO2 with cyclohexene oxide

Hydrogenolysis of mono(cyclopentadienyl)-ligated rare-earth-metal bis(alkyl) complexes Cp'Ln-(CH2SiMe3)2(THF) (Ln = Y (1a), Dy (1b), Lu (1c); Cp' = C5Me4SiMe3) with PhSiH3 afforded the mixed hydride/alkyl complexes [Cp'Ln(mu-H)(CH2SiMe3)(THF)](2) (Ln = Y (2a), Dy (2b), Lu (2c)). The overall structure of complexes 2a-c is a C-2-symmetric dimer containing a planar symmetric Ln(2)H(2) core at the center of the molecule. Deprotonation of ArOH (Ar = C6H2-Bu-t(2)-2,6-Me-4) by the metal alkyl group of 2a-c led to formation of the mixed hydride/aryloxide derivatives [Cp'Ln(mu-H)(OAr)](2) (Ln = Y (3a), Dy (3b), Lu (3c)), which adopt the dimeric structure through hydride bridges with trans-accommodated terminal aryloxide groups.

Isoprene polymerization with indolide-imine supported rare-earth metal alkyl and amidinate complexes

Reaction of 7-{(N-2,6-R)iminomethyl)}lindole (HL1, R = dimethylphenyl; HL2, R = diisopropylphenyl) and rare-earth metal tris(alkyl)s, Ln(CH2SiMe3)(3)(THF)(2), generated new rare-earth metal bis(alkyl) complexes LLn(CH2SiMe3)(2)(THF) [L = L-1: Ln = Lu. (1a), Sc (1b); L = L-2 : Ln = Lu (3a), Se (3b)] and mono(alkyl) complexes L-2 Lu-2(CH2SiMe3) (4a). Treatment of alkyl complexes 1a and 4a with N,N'-diisopropylcarbodiimide afforded the corresponding amidinates (LLu)-Lu-1{iPr(2)NC(CH2SiMe3) NiPr2}(2) (2a) and L-2 Lu-2{iPr(2)NC(CH2SiMe3)NiPr2} (5a), respectively.

Rare-earth metal complexes stabilized by amino-phosphine ligand. Reaction with mesityl azide and catalysis of the cycloaddition of organic azides and aromatic alkynes

Stoichiometric reactions between mesityl azide (MesN(3), Mes = 2,4,6-C6H2Me3) and amino-phosphine ligated rare-earth metal alkyl, LLn(CH2SiMe3) (2)(THF) (L = (2,6-C6H3Me2)NCH2C6H4P(C6H5)(2); Ln = Lu (1a), Sc (1b)), amide, LLu(NH(2,6-(C6H3Pr2)-Pr-i))(2)(THF) (2) and acetylide at room temperature gave the amino-phosphazide ligated rare-earth metal bis(triazenyl) complexes, [L(MesN(3))]Ln[(MesN(3))-(CH2SiMe3)](2) (Ln = Lu (3a); Sc (3b)), bis(amido) complex [L(MesN3)] Lu[NH(2,6-C6H3 Pr-i(2))](2) (4), and bis(alkynyl) complex (5) (L(MesN(3))Lu (C CPh)(2))(2), respectively. The triazenyl group in 3 coordinates to the metal ion in a rare eta(2)-mode via N-beta and N-gamma atoms, generating a triangular metallocycle. The amino-phosphazide ligand, L(MesN(3)), in 3, 4 and 5 chelates to the metal ion in a eta(3)-mode via N-alpha and N-gamma atoms. In the presence of excess phenylacetylene, complex 3a isomerized to 3', where the triazenyl group coordinates to the metal ion in a eta(3) mode via Na and Ng atoms.

Copolymerization of ethylene with norbornene catalyzed by cationic rare earth metal fluorenyl functionalized N-heterocyclic carbene complexes

Rare earth metal bis(alkyl) complexes attached by fluorenyl modified N-heterocyclic carbene (NHC) (Flu-NHC)Ln(CH2SiMe3)(2) (Flu-NHC = (C13H8CH2CH2(NCHCCHN)C6H2Me3-2,4,6); Ln = Sc (2a); Y (2b); Ho (2c); Lu (2d)), ((tBu)Flu-NHC)Ln(CH2SiMe3)(2) ((tBu)Flu-NHC = 2,7-(Bu2C13H6CH2CH2)-Bu-t(NCHCCHN)C6H2Me3-2,4,6; Ln = Sc (1a); Lu (1d)) and attached by indenyl modified N-heterocyclic carbene (Ind-NHC)Ln(CH2SiMe3)(2) (Ind-NHC = C9H6CH2CH2(NCHCCHN)C6H2Me3-2,4,6; Ln = Sc (3a); Lu (3d)), under the activation of (AlBu3)-Bu-i and [Ph3C][B(C6F5)(4)], showed varied catalytic activities toward homo- and copolymerization of ethylene and norbornene. Among which the scandium complexes, in spite of ligand type, exhibited medium to high catalytic activity for ethylene polymerization (10(5) g mol(Sc)(-1) h(-1) atm(-1)), but all were almost inert to norbornene polymerization. Remarkably, higher activity was found for the copolymerization of ethylene and norbornene when using Sc based catalytic systems, which reached up to 5 x 10(6) g mol(Sc)(-1) h(-1) atm(-1) with 2a. The composition of the isolated copolymer was varying from random to alternating according to the feed ratio of the two monomers (r(E) = 4.1, r(NB) = 0.013).

Rare earth metal complexes bearing thiophene-amido ligand: Synthesis and structural characterization

2,6-Diisopropyl-N-(2-thienylmethyl) aniline ( H2L) has been prepared, which reacted with equimolar rare earth metal tris( alkyl)s, Ln( CH2SiMe3)(3)( THF)(2), afforded rare earth metal mono( alkyl) complexes, LLn(CH2SiMe3)(THF)(3) ( 1: Ln = Lu; 2: Ln = Y). In this process, H2L was deprotonated by one metal alkyl species followed by intramolecular C-H activation of the thiophene ring to generate dianionic species L2- with the release of two tetramethylsilane. The resulting L2- combined with three THF molecules and an alkyl unit coordinates to Y3+ and Lu3+ ions, respectively, in a rare N,C-bidentate mode, to generate distorted octahedron geometry ligand core. Whereas, with treatment of H2L with equimolar Sc(CH2SiMe3)(3)( THF)(2), a heteroleptic complex ( HL)( L) Sc( THF) ( 3) was isolated as the main product, where the dianionic L2- species bonds to Sc3+ via chelating N, C atoms whilst the monoanionic HL connects to Sc3+ in an S,N-bidentate mode. All complexes 1-3 have been characterized by NMR spectroscopy and X-ray diffraction analysis.

Rare-Earth Metal Bis(alkyl)s Supported by a Quinolinyl Anilido-Imine Ligand: Synthesis and Catalysis on Living Polymerization of epsilon-Caprolactone

The tridentate ligand N-(2-((2,6-diisopropylphenylimino)methyl)phenyl)quinolin-8-amine (HL) was prepared. Treatment of HL with 1 equiv of Ln(CH2SiMe3)(3)(THF)(2) afforded the corresponding rare-earth metal bis(alkyl) complexes LLn(CH2SiMe3)(2)(THF)(n) (Ln = Sc, n = 0 (1); Y, n = 1 (2); Lu, n = 0 (3)) in high yields. Variable-temperature H-1 NMR spectral analysis showed that these complexes were fluxional at room temperature. Complexes 1 and 3 were THF-free, where the metal center adopted a square-pyramidal geometry, while in 2 the metal center generated a distorted octahedral geometry owing to the coordination of a THF molecule.

Highly 3,4-selective living polymerization of isoprene with rare earth metal fluorenyl N-heterocyclic carbene precursors

Fluorenyl modified N-heterocyclic carbene ligated rare earth metal bis(alkyl) complexes, (Flu-NHC)Ln(CH2SiMe3)2 (Flu-NHC = (C13H8CH2CH2(NCHCCHN)C6H2Me3-2,4,6); Ln = Sc (1a); Ln = Y (1b); Ln = Ho (1c); Ln = Lit (1d)), were synthesized and fully characterized by NMR and X-ray diffraction analyses. Complexes Ib-d with the activation of (AlBu3)-Bu-i and [Ph3C][B(C6F5)4] exhibited high activity, medium syndio-but remarkably high 3,4-regio-selectivity, and the unprecedented livingness for the polymerization of isoprene. Such distinguished catalytic performances could be maintained under various monomer-to-initiator ratios (500-5000) and broad polymerization temperatures (25-80 degrees C).

New rare earth metal bis(alkyl)s bearing an iminophosphonamido ligand. Synthesis and catalysis toward highly 3,4-selective polymerization of isoprene

Newrareearth metal bis(alkyl) complexes [(NPNPh)Ln(CH2SiMe3)(2)(THF) (NPNPh:N(Ph)PPh2=NC6H2Me3-2,4,6; Ln = Sc (3a), Ln = Y (3b), Ln = Lu (3c)) and [(NPNPy)Sc(CH2SiMe3)(2)(THF)1 (NPNPY = N(Py)PPh2=NC6H2Me3-2,4,6) (3d)) have been prepared via protonolysis reaction between rare earth metal tris(alkyl)s and the corresponding iminophosphonamines. Complexes 3a-d are analogous monomers of THF solvate. Each metal ion coordinates to a eta(2)-chelated NPN ligand and two cis-located alkyl groups, adopting tetrahedron geometry.

A Unique Mn2Gd2 Tetranuclear Compound of p-tert-Butylthiacalix[4]arene

A calixarene complex with tetragonal (Mn2Gd2III)-Gd-II tetranuclear units was synthesized in solvothermal conditions, where the addition of a small amount of water was crucial for the formation of the target compound. In the structure, two tail-to-tail p-tert-butylthiacalixarenes are located in a C-shaped mode with a dihedral angle of 14.29 degrees but not in the conventional antiparallel arrangement and form a sandwich-like subunit with an in-between Mn2Gd2 unit. Both calixarenes assume similar cone shapes of C-2v symmetry but are pinched to different extents.

Highly 3,4-Selective Polymerization of Isoprene with NPN Ligand Stabilized Rare-Earth Metal Bis(alkyl)s. Structures and Performances

Deprotonation of (ArNHPPh2NAr2)-N-1 (H[NPN](n), n = 1 - 10) by Ln(CH2SiMe3)(3)(THF)(2) (Ln = Lu, Y, Sc, Er) generated a series of rare-earth metal bis(alkyl) complexes [NPN](n)Ln(CH2SiMe3)(2)(THF)(2) (1-10), which under activation with [Ph3C][B(C6F5)(4)] and AliBu(3) were tested for isoprene polymerization. The correlation between catalytic performances and molecular structures of the complexes has been investigated. Complexes 1-5 and 8, where Ar-1 is nonsubstituted or ortho-alkyl-substituted phenyl, adopt trigonal-bipyramidal geometry. The Ar-1 and Ar-2 rings are perpendicular in 1-4 and 8 but parallel in 5. When Ar-1 is pyridyl, the resultant lutetium and yttrium complexes 9a and 9b adopt tetragonal geometry with the ligand coordinating to the metal ions in a N,N,N-tridentate mode, whereas in the scandium analogue 9c, the ligand coordinates to the Sc3+ ion in a N,N-bidentate mode. These structural characteristics endow the complexes with versatile catalytic performances, With increase of the steric bulkiness of the ortho-substituents Ar-1 and Ar-2, the 3,4-selectivity increased stepwise from 81.6% for lutetium complex 1 to 96.8% for lutetium complex 6 and to 97.8% for lutetium complex 7a. However, further increase of the steric bulk of the ligand led to a slight drop of 3,4-selectivity for the attached complex 5 (95.1%).

Synthesis of the first rare earth metal bis(alkyl)s bearing an indenyl functionalized N-heterocyclic carbene

Treatment of indenyl-modified imidazolium bromide [C9H7CH2CH2(NCHCHN(C6H2Me3-2,4,6)CH)Br] ((IndH-NHC-H)Br) with rare earth metal tetra(alkyl) lithium (Ln(CH2SiMe3)(4)Li(THF)(4)) or with (trimethylsilylmethyl)lithium (LiCH2SiMe3) and rare earth metal tris(alkyl)s (Ln(CH2SiMe3)(3)(THF)(2)) sequentially afforded the first NHC-stabilized monomeric rare earth metal bis(alkyl) complexes (Ind-NHC)Ln(CH2SiMe3)(2) (1, Ln = Y; 2, Ln = Lu; 3, Ln = Sc) via double-deprotonation reactions. Complexes 1-3 are THF-free isostructural monomers. The monoanionic Ind-NHC species bond to the central metal ion in a eta(5):kappa(1) constrained geometry configuration (CGC) mode, which combine with the two cis-located alkyl moieties to form a tetrahedron ligand core, leading to the chirality of the complexes. Under the presence of activators AlEt3 and [Ph3C][B(C6F5)(4)], complex 2 showed catalytic activity toward the polymerization of isoprene to afford 3,4-regulated polyisoprene (91%).

Vinylic polymerization of norbornene by neutral nickel(II)-based catalysts

Neutral Ni(II) salicylaldiminato complexes activated with modified methylaluminoxane as catalysts were used for the vinylic polymerization of norbornene. Catalyst activities of up to 7.08 x 10(4) kg(pol)/(mol(Ni) (.) h) and viscosity-average molecular weights of polymer up to 1.5 x 10(6) g/mol were observed at optimum conditions. Polynorbornenes are amorphous, soluble in organic solvents, highly stable, and show glass-transition temperatures around 390 degreesC. Catalyst activity, polymer yield, and polymer molecular weight can be controlled over a wide range by the variation of the reaction parameters such as the Al/Ni ratio, monomer/catalyst ratio, monomer concentration, polymerization reaction temperature, and time.

Syntheses, crystal structures and magnetic properties of two heterometallic coordination polymers

Two heterometallic chain coordination polymers with the chemical formula {[Cu2Mn2L2(CH3OH)(H2O)] center dot 0.5CH(3)OH center dot 0.5CH(3)CH(2)OH}(n) (1) and {[Cu2Co2L2(H2O)(2)] center dot H2O}(n) (2) have been synthesized and characterized by IR, UV spectroscopy and single-crystal X-ray structural analysis, where H4L = 2-hydroxy-3-[(E)-({2-[(2-hydroxybetizoyl)amino]ethyl}imino)methyl] benzoic acid. Magnetic measurements showed that the two compounds exhibit antiferromagnetic coupling exchange interactions, and satisfactory fittings to the observed magnetic susceptibility data were obtained by assuming a linear four-spin arrangement with two isotropic magnetic exchange interactions.