Reaction Of CrCl3 Research Articles

Diacetonitrile[N,N′-bis(2,6-diisopropylphenyl)ethane-1,2-diimine]dichloridochromium(II) acetonitrile solvate

The title compound, [CrCl2(CH3CN)2(C26H36N2)]·CH3CN, was synthesized by the reaction of CrCl2(THF)2 with N,N′-bis­(2,6-diisopropyl­phen­yl)ethane-1,2-diimine in dichloro­methane/acetonitrile. The chromium center is coordinated by two N atoms of the chelating diimine ligand, two chloride ions in a trans configuration with respect to each other, and by two N atoms of two acetonitrile mol­ecules in a distorted octa­hedral geometry.

Ethylene polymerization by the new chromium catalysts based on amino‐pyrrolide ligands

AbstractA series of amino‐pyrrolide ligands (1–4a) and their derivatives amino‐thiophene ligand (5a), amino‐indole ligand (6a) were prepared. Chromium catalysts, which were generated in situ by mixing the ligands with CrCl3(thf)3 in toluene, were tested for ethylene polymerization. The preliminary screening results revealed that the tridentate amino‐pyrrolide ligands containing soft pendant donor, 3a, 4a/CrCl3(thf)3 systems displayed high catalytic activities towards ethylene polymerization in the presence of modified methyaluminoxane. The electronic and steric factors attached to the ligand backbone significantly affected both the catalyst activity and the polymer molecular weight. Complex 4b was obtained by the reaction of CrCl3(thf)3 with one equivalent of the lithium salts of 4a, which was the most efficient ligand among the tested ones. The effect of polymerization parameters such as cocatalyst concentration, ethylene pressure, reaction temperature, and time on polymerization behavior were investigated in detail. The resulting polymer obtained by 4b display wax‐like and possess linear structure, low molecular weight, and unimodal distribution. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 713–721, 2009

Synthesis, Characterization, and Electronic Structure of Diimine Complexes of Chromium

We have prepared and structurally characterized several complexes of chromium coordinated by diimine (or 1,4-diazadiene) ligands, that is, Ar-N=C(R)-(R)C=N-Ar (RL(Ar)) (where Ar = 2,6-diisopropylphenyl ("iPr") or 2,6-dimethylphenyl ("Me") and R = H or Me). The reaction of CrCl2 with HLiPr gave dinuclear [(HLiPr)Cr]2(mu-Cl)3(Cl)(THF) when isolated from Et2O; in THF solution, however, the product exists as mononuclear (HLiPr)CrCl2(THF)2. Two isostructural derivatives, (MeLMe)CrCl2(THF)2 and (HL(Me))CrCl2(THF)2, have also been prepared. Furthermore, the bis-ligand complex, (HLiPr)2Cr, has been prepared along with its reduction product, Li(THF)4[(HLiPr)2Cr]. We have also synthesized the tetracarbonyl complex, (HLiPr)Cr(CO)4, by addition of HLiPr to Cr(CO)4(NCCH3)2. The structure and variable temperature magnetic susceptibility of the previously reported Cr halide dimer, [(HLiPr)Cr(mu-Cl)]2, is also discussed in detail. All of the diimine complexes have been characterized structurally, spectroscopically, and magnetically, and their electronic structures are discussed with the aid of density-functional theory calculations.

Chromium complexes ligated by 2-carbethoxy-6-iminopyridines: Synthesis, characterization and their catalytic behavior toward ethylene polymerization

The titled chromium complexes ( C1– C6) were prepared by the reaction of CrCl 3(THF) 3 with the corresponding 2-carbethoxy-6-iminopyridines ( L1– L6) in dichloromethane. All the complexes were characterized by IR spectroscopy and elemental analysis. The unambiguous solid-state structures of C1, C3 and C5 were determined by X-ray crystallography. The chromium core was found to be coordinated by a molecule of 2-carbethoxy-6-iminopyridine and three atoms of chlorine to form a distorted octahedral coordination geometry. Activated with ethylaluminum dichloride (EtAlCl 2), these complexes showed notable catalytic activities for ethylene polymerization. The nature of the ligands and reaction parameters affected the properties of the resultant polyethylenes.

Role of the Metal Oxidation State in the SNS−Cr Catalyst for Ethylene Trimerization: Isolation of Di- and Trivalent Cationic Intermediates

The reaction of the highly selective [CySCH2CH2N(H)CH2CH2SCy]CrCl3 catalyst precursor with alkyl aluminum activators was examined with the aim of isolating reactive intermediates. Reaction with Me3Al afforded a cationic trivalent chromium alkyl species {[CySCH2CH2N(H)CH2CH2SCy]CrMe(mu-Cl)}2{(AlMe3)2(m-Cl}2.(C7H8)2 (1a). Although it was not possible to obtain crystalline samples of sufficient quality from the reaction with MAO (the most preferred activator), the near-to-identical EPR spectra indicated a very close structural similarity with 1a. Ethylene oligomerization tests clearly revealed that 1 and other cationic trivalent dimeric complexes {[CySCH2CH2N(H)CH2CH2SCy] CrCl(mu-Cl)}2{AlCl4}2.(C7H8)1.5 (2), monomeric [(CySCH2CH2N(H)CH2CH2SCy)CrCl2 (THF)][AlCl4] (3), and {[CySCH2CH2N(H)CH2CH2SCy]Cr(eta2-AlCl4)}{Al2Cl7} (4) adducts display the same catalyst selectivity as the [CySCH2CH2N(H)CH2CH2SCy]CrCl3 complex and, therefore, are probably all precursors to the same catalytically active species. 2, 3, and 4 were obtained upon treatment of [CySCH2CH2N(H)CH2CH2SCy] CrCl3 with different stoichiometric ratios of AlCl3.. When i-BAO activator was used, reduction of the metal center occurred readily, affording {([CySCH2CH2N(H)CH2CH2S Cy]Cr)(mu-Cl)]2}{(i-Bu)2AlCl2}2 (5). 5 is also a selective catalyst, thus indicating that trivalent species are most probably precursors to a divalent catalytically active complex. Reaction of CrCl2(THF)2 with the ligand afforded the labile divalent adduct [CySCH2CH2N(H)CH2CH2SCy]CrCl2(THF) (6), also catalytically active and selective. Instead, deprotonation of the ligand with n-BuLi followed by reaction with CrCl2(THF)2 gave the dinuclear complex [(mu-CySCH2CH2NCH2CH2SCy)CrCl]2 (7), which did not produce oligomers.

A Chromium-Diphosphine System for Catalytic Ethylene Trimerization: Synthetic and Structural Studies of Chromium Complexes with a Nitrogen-Bridged Diphosphine Ligand withortho-Methoxyaryl Substituents

To gain molecular-level insight into the important features of a chromium-diphosphine catalytic system for ethylene trimerization, the coordination chemistry of chromium with “PNP” ligands (PNPOMe = (o-MeOC6H4)2PN(CH3)P(o-MeOC6H4)2, Pt-BuNi-amylPOMe = (2-MeO-4-t-BuC6H3)2PN(i-amyl)P(2-MeO-4-t-BuC6H3)2) has been explored. Chromium(0) carbonyl complexes have been synthesized by CO displacement with diphosphine. Oxidation of Cr(CO)4{κ2-(P,P)-(PNPOMe)} with I2, Br2, and PhICl2 generates the corresponding chromium(III) halide complexes. Chromium(III) complexes CrCl3{(κ3-(P,P,O)-(PNPOMe)}, CrCl3{κ3-(P,P,O)-(Pt-BuNi-amylPOMe)}, and CrCl2(CH3){κ3-(P,P,O)-(PNPOMe)} can be synthesized by metalation with CrCl3(THF)3 or CrCl2(CH3)(THF)3. Reaction of CrCl3{κ3-(P,P,O)-(PNPOMe)} with o,o‘-biphenyldiyl diGrignard affords CrBr(o,o‘-biphenyldiyl){κ3-(P,P,O)-(PNPOMe)}. Single-crystal X-ray diffraction studies show that the Cr−O and Cr−P distances can vary significantly as a function of metal oxidation state and the other lig...

A Thermal Reduction–Nitridation Route to Nanocrystalline Chromium Nitride (CrN)

Abstract Nanocrystalline CrN was synthesized via thermal reduction–nitridation route by the reaction of CrCl3 with NH4Cl and Na in an autoclave at 400 °C. X-ray powder diffraction pattern indicated that the product was cubic CrN. An atomic ratio of Cr to N of 1.08:1 was determined from X-ray photoelectron spectra. Transmission electron microscopy image showed that the sample consisted of particles with the diameters of 20–40 nm.

Synthesis and X-ray crystal structure of Cr(NR2)3 (R = CH(Me)Ph)

The reaction of CrCl3 with three equivalents of the lithium salt of [R-(R*,R*)]-(+)-bis(α-methylbenzyl)amine produces the trigonal planar Cr(III) tris(amido) complex. The X-ray structure of Cr[N{CH(Me)Ph}2]3 is reported.Key words: chromium, X-ray crystal structure, amido ligands, chiral ligands.

Synthesis, structural characterization and ethylene polymerization behavior of complex [Ph 4P][CrCl 3{HB(pz) 3}] [HB(pz) 3 = hydrotris(1-pyrazolyl)borate

Reaction of CrCl 3(THF) 3 with K[HB(pz) 3] in THF leads to the formation of the complex K[CrCl 3{HB(pz) 3}] ( 1). The salt metathesis of complex 1 with [Ph 4P]Br in CH 2Cl 2 yields the complex [Ph 4P][CrCl 3{HB(pz) 3}]( 2). The structure of complex 2 · CHCl 3 has been determined by single crystal X-ray diffraction. In the anion the metal centre shows a distorted octahedral geometry with the hydrotris(1-pyrazolyl)borate bonded as N, N′, N″-donor tripod ligand and three chloride atoms completing the co-ordination sphere. Complex 2 in the presence of MAO leads to the formation of an active catalyst for the polymerization of ethylene.

Trimethylsilylcyclopentadienylchromium(III) complexes with diphenyl-2-pyridylphosphine: synthesis, structural characterisation and catalytic behaviour of [(C 6H 5) 2PC 5H 4NH][(η 5-Me 3SiCp)CrCl 3

Reaction of CrCl 3 with LiCpSiMe 3 in THF leads to the formation of a solvated intermediate, [(η 5-Me 3SiCp)CrCl 2(THF)], which in turn reacts with diphenyl-2-pyridylphosphine to yield the complex [(C 6H 5) 2PC 5H 4NH][(η 5-Me 3SiCp)CrCl 3] ( 1) in 66% yield. As a secondary product was isolated the neutral complex [(η 5-Me 3SiCp)CrCl 2{(C 6H 5) 2PC 5H 4N}] ( 2) in 5% yield. The structure of complex 1 has been determined by single crystal X-ray diffraction. In the anion the metal centre shows a pseudo-octahedral geometry with the centroid of the trimethylsilylcyclopentadienyl ligand occupying the centre of three octahedral sites, and three chloride atoms completing the co-ordination sphere. Complex 1 in the presence of MAO leads to the formation of an active catalyst for the polymerization of ethylene.

Reaction of Chromium(III) Chloride with the Cycloheptadienyl Anion: Susceptibility of Edge Bridges To C−H Activation Reactions

The reaction of CrCl3 with 3 equiv of the cycloheptadienyl anion leads to Cr(η7-C7H7)(η4-C7H10) (C7H10 = cycloheptadiene), through a process in which one ligand loses two hydrogen atoms while the other ligand gains one. The same complex had been reported from an entirely different route, involving the reaction of chromium(III) salts with Grignard reagents in the presence of cycloheptadiene and cycloheptatriene. The formulation of the complex has been confirmed by a low-temperature X-ray diffraction study. Related reactions have been found to lead to M(η7-C7H7)(η5-C7H9) (M = Ti, V; C7H9 = cycloheptadienyl) complexes. The preferential formation of one aromatic ηn-CnHn ligand seems to provide the driving force favoring the isolated products and related species having other values of n.

The Unusual Stability of Homoleptic Di- and Tetravalent Chromium Alkyls

Reaction of CrCl3(THF)3 with 3 equiv of R−M [R = Me3CCH2 (a), Me3SiCH2 (b)] afforded either the previously reported tetravalent homoleptic R4Cr (1a, b) [M = MgCl] or the unprecedented divalent and tetranuclear homoleptic [R2Cr]4 (2b) [M = Li]. Both types of compounds display a remarkable chemical inertness toward proton transfer agents but readily react with ethylene.

Chromium complexes of an isomeric N-donor ligand, 2-[(N-arylamino)phenylazo]pyridine: amination reactions, X-ray structure, and redox properties.

The chromium chemistry of two positional isomers of the ligand 2-[(N-arylamino)phenylazo]pyridine (HL(1)and HL(2)) are described. While the ligand HL(1) coordinates as a bischelating tridentate N,N,N-donor, [L(1)](-), with deprotonation of the amine nitrogen, its isomer HL(2) coordinates as a neutral bidentate N,N-donor. The amine nitrogen in this case remains protonated. Thus the reaction of CrCl(3).nH(2)O with HL(1) produced the brown cationic complex, [Cr(L(1))(2)](+), [1](+). The representative X-ray structure of [1a](ClO(4)) is reported. The two azo nitrogens of the anioinc tridentate ligand approach the metal center closest with Cr(1)-N(azo) av 1.862(6) A. There is a significant degree of ligand backbone conjugation in the coordinated ligands, which resulted in shortening of the C-N distances and also in lengthening of the diazo (N=N) distances. Two synthetic approaches for the synthesis of chromium complexes of HL(2) are investigated. The first approach is based on the substitution reaction, wherein all the coordinated CO ligands of Cr(CO)(6) were completely substituted by the three bidentate HL(2) ligands to produce a violet complex [Cr(HL(2))(3)]. The second approach is based on para-amination reaction of coordinated 2-(phenylazo)pyridine (pap). Thus the reaction of an inert complex, [CrCl(2)(pap)(2)], with ArNH(2) yields a mixed ligand complex, [CrCl(2)(pap)(HL(2))], 3. In this reaction one of the two coordinated pap ligands in [CrCl(2)(pap)(2)] undergoes amination at the para carbon (with respect to the diazo function) to yield HL(2) in situ. This metal-promoted transformation is authenticated by the X-ray structure determination of a representative complex, [CrCl(2)(pap)(HL(2a))], 3a. Notable differences in bond distances along the ligand backbones of the two coordinated ligands in 3a indicate different levels of metal-ligand overlap in this complex. All the chromium complexes of HL(2) are characterized by their intense blue-violet color. The frequencies of the visible range transitions in these complexes linearly correlate with the Hammett's substitution constant. Intraligand charge-transfer transitions in the visible region are believed to be responsible for the intense color. Redox properties of all these complexes are reported.

Synthesis and structure of a chromium(III) complex coordinated by 1,1′-Bi-2-naphtholate ligands and its catalytic activity for ethylene polymerization

Reaction of CrCl 3(THF) 3 with rac-Li 2(binol) (binol=1,1′-bi-2-naphtholate) gave a new chromium(III) complex, [Li(THF)] 3[Cr(binol) 3]·3(toluene) ( 1). The X-ray crystallographic structure of 1 revealed its propeller-like structure similar to those of the reported rare earth analogues. The complex 1 showed moderate catalytic activities for ethylene polymerization upon activation with modified methylaluminoxane (MMAO) and with diethylaluminum chloride. When 1 was supported on the silica surface, activity increased to two times of homogeneous 1/MMAO system.

Synthesis, X-ray structure, and polymerisation activity of a bis(oxazolinyl)pyridine chromium(iii) complex

The complex [2,6-bis[(4S)-isopropyl-2-oxazolin-2-yl]pyridine]CrCl3, prepared by reaction of CrCl3(THF)3 with 2,6-bis[(4S)-isopropyl-2-oxazolin-2-yl]pyridine, catalyses ethylene homopolymerisation and ethylene/1-hexene copolymerisation in the presence of MAO.

Synthesis, Characterization, and Reactivity of Chromium Boratabenzene Complexes

In contrast to the reactivity observed with the isoelectronic cyclopentadienyl salts, the reaction of CrCl3(THF)3 with boratabenzene anions results in the formation of Cr(II) complexes. Thus, addition of Li(C5H5B−Me) to CrCl3(THF)3 in THF gives (C5H5B−Me)2Cr (3). Similarly, Li(C5H5B−NMe2) and CrCl3(THF)3 yield (C5H5B−NMe2)2Cr (4), while Li(C5H5B−Ph) and CrCl3(THF)3 provide (C5H5B−Ph)2Cr (5). Compounds 3−5 were characterized by single-crystal X-ray diffraction studies, and all possess typical sandwich structures. The reaction of borabenzene−ligand adducts with suitable Cr(III) starting materials provides boratabenzene−Cr(III) complexes. Addition of C5H5B−PMe3 (Bb-PMe3) to MeCrCl2(THF)3 in benzene gives (C5H5B−Me)CrCl2(PMe3) (6) in low yield. Treatment of MeCrCl2(THF)3 with the pyridine adduct of borabenzene, C5H5B−NC5H5 (Bb-Py), does not work effectively. The composition of one of the products from this reaction, the binuclear dimer [(C5H5B−Me)CrClMe]2 (7), indicates Me/Cl redistribution processes. Treatme...

An unprecedented quadruply bonded compound with a bridging chlorine atom: Cr 2[( o-ClC 6H 4N) 2CH] 3( μ-Cl)

Reaction of CrCl 2 and Li[( o-ClC 6H 4N) 2CH] in THF gives Cr 2[( o-ClC 6H 4N) 2CH] 3( μ-Cl). This compound has three bridging formamidinates and a bridging chlorine atom. The resulting A-frame is the first having a quadruply bonded M 2 4+ unit. The Cr–Cr distance of 1.940(1) Å is in the normal range for a short quadruple bond.

Syntheses, crystal structures and properties of mononuclear chromium(III) and dinuclear vanadium(III) and copper(II) complexes with a bis-bipyridyl ligand †

The reaction between [VCl3(thf)3] and the bis-bidentate ligand L [L = 1,2-bis(2,2′-bipyridyl-6-yl)ethane] in MeOH gave the oxo-bridged dinuclear complex [V2OCl2L2]Cl2 1, which contains a near linear V–O–V unit. Reaction of CrCl3·6H2O with L in refluxing MeOH gave mononuclear trans-[CrCl2L]Cl 2 with the ligand L co-ordinated equatorially. Equimolar reaction of L with [Cu2(OAc)4(H2O)2] in EtOH followed by addition of NaClO4 yielded the dinuclear complex [Cu2(OAc)2.4(OEt)0.6L]ClO4 3, whose cation contains a [Cu2(OAc)2(OAc0.4/OEt0.6)]+ core, with two bridging OAc– ligands and a bridging oxygen atom shared by disordered OEt– and monodentate OAc– ligands. The analogous reaction with addition of HBF4 gave [Cu2F(OAc)2L]BF4 4, which contains two bridging OAc– ligands and a bridging F– atom. Compound 1 shows strong ferromagnetic coupling between vanadium(III) ions with J > 100 cm–1 resulting in only the S = 2 ground state being populated, whereas 4 shows weak ferromagnetic coupling, J ≈ +8 cm–1 (H = –2JSiSjconvention) and a S = 1 ground state.

Cr (en) 2SbS 3: : the first example of a single SbS 3 ligand in a transition-metal-complex, and the crystal structure of Cr (en) 3SbS 4

Application of mild solvothermal conditions in the reaction of CrCl 3·8H 2O, Sb 2S 3 and S in an aqueous solution of ethylenediamine (en) yielded the two novel thioantimonate compounds Cr (en) 2SbS 3 (1) and [Cr (en) 3]SbS 4 (2). The crystal structure of 1 consists of neutral chromium centered complexes, where chromium is chelated by two ethylendiamine molecules and one bidentate SbS 3 3− group giving a distorted octahedral coordination. Compound 1 is the first example of a transition metal complex with a SbS 3 3− ligand. Slightly different synthetic conditions lead to the formation of 2, which consists of isolated octahedral coordinated Cr (en) 3 3 cations and tetrahedral SbS 4 3− anions. The crystal structures were determined and the thermal decomposition was investigated.

Synthesis and Properties of New Chromium(II) Organophosphonates

A new series of chromium(II)-alkylphosphonates, Cr[RPO3]·H2O (R = CH3, C2H5), and chromium(II) ethylenebis(phosphonate), Cr2[O3P−(CH2)2−PO3]·3H2O, have been synthesized by reaction of CrCl2 and the corresponding phosphonic acid in water in the presence of urea. The (2-aminoethyl)phosphonic acid reacts with CrCl2 to give an unexpected compound of formula Cr[H3N−(CH2)2−PO3(Cl)]. All the compounds are sensitive to the air, except for the latter one. They were characterized by X-ray powder diffraction, thermogravimetry, and UV−visible and infrared spectroscopy, and their magnetic properties were studied by a SQUID magnetometer. The metal ion is in the high-spin d4 configuration, and it appears to have an octahedral coordination. Cr[CH3PO3]·H2O behaves as a “weak” ferromagnet, with a Neel temperature of TN = 35 K, and it represents an example of an unusual kind of molecular-based magnetic material, having a finite zero-field magnetization. The thermal variation of the magnetic susceptibility of Cr2[O3P−(CH2)2−...