16997-54-9

Upstream product

• 75-77-4 chloro-trimethyl-silane 
• 109-99-9 tetrahydrofuran 
• 10025-73-7 chromium(III) chloride 
• 10108-64-2 cadmium(II) chloride 
• 16284-59-6 chromium chloride 
• 12110-37-1 tricarbonyl(naphthalene)chromium⁽⁰⁾ 
• 98101-99-6 CrCl₃(acetonitrile)4 

Downstream Products

• 676-55-1 methane-d2 
• 676-80-2 methane-d3 
• 1291-32-3 zirconocene dichloride 
• 632323-54-7 nitridobis(2-benzyliminomethylphenolato)chromium(V) 
• 105241-53-0 Mn(Cl)(N,N'-ethylenebis(salicylidenamine))*CH₃CN 
• 1271-54-1 bis(benzene)chromium⁽⁰⁾ 
• 12095-46-4 [(η6-Ph₂)(η6-PhH)Cr] 
• 34788-74-4 pentaaquabenzylchromium(II) 

Relevant academic research and scientific papers

Spin structure of surface-supported single-molecule magnets from isomorphous replacement and X-ray magnetic circular Dichroism

Surface-supported arrays of Fe4-type Single-Molecule Magnets retain a memory effect and are of current interest in the frame of molecule-based information storage and spintronics. To reveal the spin structure of [Fe4(L)2(dpm)6] (1) on Au, an isomorphous compound [Fe3Cr(L)2(dpm)6] was synthesized and structurally and magnetically characterized (H3L is tripodal ligand 11-(acetylthio)-2,2-bis(hydroxymethyl)undecan-1-ol and Hdpm is dipivaloylmethane). The new complex contains a central Cr3+ ion and has a S = 6 ground state as opposed to S = 5 in 1. Low-temperature X-ray Magnetic Circular Dichroism studies at Fe- and Cr-L2,3 edges revealed that the antiparallel alignment between Fe and Cr spins is preserved on surfaces. Moreover, the different Fe-L2,3 spectral features found in the homo- and heterometallic species disclose the opposing contribution of the central Fe3+ ion in the former compound, proving that its ferrimagnetic spin structure is retained on surfaces.

Pyrene-Decoration of a Chromium(0) Tris(diisocyanide) Enhances Excited State Delocalization: A Strategy to Improve the Photoluminescence of 3d6 Metal Complexes

There is a long-standing interest in iron(II) complexes that emit from metal-to-ligand charge transfer (MLCT) excited states, analogous to ruthenium(II) polypyridines. The 3d6 electrons of iron(II) are exposed to a relatively weak ligand field, rendering

Photolytic reactivity of organometallic chromium bipyridine complexes

Known stable [Cr(bpy)2(Ph)2](BPh4) complexes undergo reductive elimination of biphenyl with visible-light photolysis using household incandescent or compact fluorescent light bulbs. A series of [Cr(R-bpy)2(Ar)2](X) complexes (R = H or CMe3; Ar = Ph, C6H4-CMe3, or C6H4-OMe; X = I, BPh4, or PF6) were prepared, and the effect of varying the bipyridine and aryl ligands on the UV-visible spectra and electrochemistry of the chromium(III) complexes was investigated. Photolysis of a mixture of two different bis(aryl) complexes gave only the homocoupled biaryl products by1H NMR and gas chromatography/mass spectrometry analysis. The initial product of photoinduced reductive elimination of [Cr(bpy)2(Ar)2](PF6) was trapped with bipyridine to generate [Cr(bpy)3](PF6) and with benzoyl peroxide to form [Cr(bpy)2(O2CPh)2](PF6). The latter chromium(III) bis(benzoate) complex was also synthesized by the addition of bipyridine and PhCO2H to Cp2Cr, followed by air oxidation. The neutral Cr(bpy)(S2CNMe2)Ph2complex also generated biphenyl upon visible-light photolysis. While the treatment of Cr(tBu-bpy)(dpm)Cl2[dpm = (OCtBu)2CH] with AgO2CPh gave trans-Cr(tBu-bpy)(dpm)(O2CPh)2, reaction of the dichloro precursor with PhMgCl produced anionic [Cr(tBu-bpy)Ph3]?with [Mg(dpm)(THF)4]+as the countercation, with both complexes characterized by single-crystal X-ray diffraction. Protonolysis of Cr(bpy)Ph3(THF) with 8-hydroxyquinoline produced Cr(bpy)(quin)Ph2, which generated biphenyl under visible-light photolysis, and the initial product of reductive elimination was trapped by bipyridine or benzoyl peroxide. A related Cr(bpy)(quin)2complex was synthesized by protonolysis of Cr(bpy)[N(SiMe3)2]2and characterized by single-crystal X-ray diffraction.

Synthesis, characterization and reactivity of vanadium, chromium, and manganese PNP pincer complexes

The synthesis of a series of vanadium, chromium, and manganese PNP complexes of the types [M(PNP)Cl3] (M = V, Cr) and [M(PNP)Cl2] (M = Cr, Mn) is reported. Vanadium and manganese PNP pincer complexes are described for the first time. All complexes are characterized by their magnetic moments, elemental analysis, and ESI MS. In addition, some compounds are characterized by X-ray crystallography. In a preliminary study, these complexes catalyze the oxidative homo-coupling of aryl Grignard reagents in the presence of MeI as oxidizing agents to give symmetrical biaryls, but are inactive in Kumada cross-coupling reactions. The reactivity of V(III), Cr(III), Cr(II) and Mn(II) is compared with related Fe(II) and Co(II) complexes of the types [Fe(PNP-iPr)Cl2], and [Co(PNP-iPr)Cl2]. In all cases, good to excellent isolated yields are obtained. However, since the respective metal chlorides in the absence of PNP ligands exhibited comparable reactivities, the new PNP complexes offer no real advantage for this type of coupling reactions.

N-Phosphanyl- and N,N′-Diphosphanyl-Substituted N-Heterocyclic Carbene Chromium Complexes: Synthesis, Structures, and Catalytic Ethylene Oligomerization

The chromium(II) complexes [CrCl2(t-BuNHC,P-κC)2] (1), [CrCl2(MesNHC,P-κC)2] (2), [CrCl2(DippNHC,P-κC)2] (3), and [CrCl2(P,NHC,P-κC)2] (4) containing the N-phosphanyl- or N,N′-diphosphanyl-substituted N-heterocyclic carbene (NHC) hybrid ligands t-BuNHC,P (1-(di-tert-butylphosphino)-3-tert-butylimidazol-2-ylidene), MesNHC,P (1-(di-tert-butylphosphino)-3-mesitylimidazol-2-ylidene), DippNHC,P (1-(di-tert-butylphosphino)-3-(2,6-diisopropylphenyl)imidazol-2-ylidene), and P,NHC,P (1,3-bis(di-tert-butylphosphino)imidazol-2-ylidene), respectively, were prepared from CrII ([CrCl2(thf)2]) or CrIII ([CrCl3(thf)3] or [Cr(Me)Cl2(thf)3]) precursors. The solid-state structures of these four complexes show square-planar CrII centers, with two trans chloride and two monodentate CNHC donors. Alkylation of 3 and 4 with [Mg(benzyl)2(thf)2] led to the formation of the σ complexes [Cr(benzyl)3(DippNHC,P-κC,κP)] (5) and [Cr(benzyl)3(P,NHC,P-κC,κP)] (6), respectively, with five-coordinate distorted-square-pyramidal CrIII coordination, comprising a chelating ligand through the CNHC and one P donor and three benzyl groups. These complexes were used as precatalysts in ethylene oligomerization, and it was found that the nature of the cocatalyst used and the metal oxidation state have a remarkable influence on the catalytic properties. The CrIII/MAO systems displayed superior catalytic performance (TOF values up to 16320 mol of C2H4/((mol of Cr) h) for 6) and gave mostly oligomers. Interestingly, the oligomers obtained with complex 3 were almost exclusively 1-hexene and 1-butene when the reaction was initiated at 30 °C. The overall activities and selectivities were also affected by the initial reaction temperature and the nature of the solvent. With AlEtCl2 (EADC) as cocatalyst, polyethylene was predominately formed. (Chemical Equation Presented).

Synthesis and molecular structure of the tetranuclear μ4-oxo-centered chromium complex [Cr4(CH2CH2CH2NMe2) 4(μ4-O)(μ-Cl)6]

The complex [CrCl3(THF)3] reacts with Li(CH2CH2CH2NMe2) in THF at room temperature (r.t.) to form the tetranuclear complex [Cr4(CH2CH2CH2NMe2) 4(μ4-O)(μ-Cl)6] (1) where each chromium atom has a distorted octahedral coordination geometry with an oxygen atom shared among the four metal ions.

The synthesis and X-ray structure of trans-[CrCl2(nPrNH2)4]BF4*H2O and the thermal and Hg(2+) -assisted chloride release kinetics from some trans-(CrCl(N)4](1+) complexes

Complexes of the type trans-[CrCl2(RNH2)4]Cl (R = Et, nPr, nBu) are readily formed from [CrCl3(thf)3] and four equivalents of the amine in tetrahydrofuran (thf). The structure of trans [CrCl2(nPrNH2)4]BF4*H2O (triclinic, P1, a = 5.828, b = 10.030, c = 10.403?, α = 89.37, β = 89.37, .gama. = 87.78, V = 582.1?(3), Z = 1) has beeen determined by single crystal X-raydiffraction. The Two CrCl bonds are approximately equivalent (Cr-Cl(1) = 2.325(3), Cr-Cl(2) = 2.326(3)) and of the (cis) nPrNH2 'arms' are above and two below the Cr(N)4 plane. The rates of the first chloro ligand from trans-[CrCl2(RNH2)4](1+) (R = Et, nPr, nBu) are about 16 times slower than that for R = H. Spectroscopically determined kinetic parametrs (0.05 M HNO3, 25°C) are R = H: 1E+6 k(s**-1) = 45.9, ΔH.thermod. (kJ mol**-1) = 94.9, ΔS.thermod. (J K**1 mol**-1) = -10; R = Et: 1E+7 k = 2.88, ΔH.thermod. = 116, ΔS.thermod. = +39; R = nPr: 1E+7 k = 6.70, ΔH.thermod. = 101, ΔS.thermod. = -6; R = nBu: 1E+7 k = 4.90, ΔH.thermod. = 116, ΔS.thermod. = +43. Hg(2+) -assisted chloride release kinetocs for first step in the aquation of several trans-[CrCl2(N)4](1+) systems have been measured in 50:50 dmf:aq. HClO4 (I = 0.5 M). The activation entropy data suggest that the thermal aquation processes for trans-[CrCl2(N)4](1+) are more widely spread across the interchange mechanistic spectrum than those for the analogous Co(III) systems.

Organometallic oxides: Preparation and properties of the tetrahedral (Td) cubane [(η-C5(CH3)5)Cr(μ3-O)] 4 and comparison with the D2 [(η-C5H5)Cr(μ3-O)]4 and D2d [(η-C5H4CH3)Cr(μ3-O)] 4

The cubane [(η-C5(CH3)5)Cr(μ3-O)] 4 (3) was prepared by the reaction between (η-C5(CH3)5)2Cr (4) and N2O (1:1 molar ratio) in toluene at 80°C. The structures of 3 and 4 have been determined by X-ray diffraction. 3: Mr = 813.0, triclinic, P1, a = 10.876 (2) A?, b = 10.923 (2) A?, c = 18.105 (2) A?, α = 83.75 (1)°, β = 83.89 (1)°, γ = 66.86 (1)°, Z = 2, R = 0.060, Rw = 0.080 for 4121 observed reflections and 463 refined parameters. 4: Mr = 322.45, orthorhombic, Ccmm, a = 8.6857 (5) A?, b = 14.7842 (8) A?, c = 29.2031 (15) A?, Z = 8, R = 0.079, Rw = 0.092 for 816 observed reflections and 100 parameters. 3 has Td symmetry, the six Cr-Cr distances averaging 2.834 (2), and the Cr-O distances, 1.945 (5) A?. The Cr-O-Cr angles average 93.5 (2); the O-Cr-O angles, 86.4 (2)°. 3 is antiferromagnetic, the magnetic moment increasing from 1.10 at 4.5 to 1.94 μB at 84.5 K; at 295 K the moment was 3.74 μB. The physical and chemical properties of 3 are compared to those of [(η-C5H5)Cr(μ3-O)]4, (1), which has D2 symmetry, and to [(η-C5H4CH3)Cr(μ3-O)] 4, which has D2d symmetry. It is concluded that the η-C5R5 ring does not influence the [Cr(μ3-O)]4 core. Whereas 1 lost all η-C5H5 ligands rapidly on treatment with O2, 3 was essentially inert to it.

THE MECHANISM OF THE ADDITION OF TETRACHLOROMETHANE TO ALKENES IN THE PRESENCE OF 6-C10H8)>

The title reaction has been examined in detail and is shown to proceed via a non-chain catalysed mechanism involving free radical intermediates.