Chemical Behavior of a Pair of (COD)CpRh and −Ir Complexes with Pendant Peripheral −B(C6F5)2Groups

Herrmann, Christoph S.; Kehr, Gerald; Fröhlich, Roland; Erker, Gerhard

doi:10.1021/om800195d

Cited by 14 publications

(6 citation statements)

References 118 publications

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“…Borane ligation to the cyano groups in compound 11 is indicated by the 11 B NMR chemical shift of −9.2 ppm, characteristic of nitrile-coordinated B(C 6 F 5 ) 3. Furthermore, Δδ (p, m) values of 7.7 and 7.5 ppm in the 19 F NMR for compounds 10 and 11 are consistent with neutral, four-coordinate borane adducts of B(C 6 F 5 ) 3 . Finally, the 13 C NMR resonances for the Ar -CN units at 136.60–136.83 ( Ar C  N -CH ) and 126.43–134.24 ( Ar C  N -CH ) ppm for 10 and 11 also support full borane coordination to both nitrile functions on the N -aryl groups.…”

Section: Resultssupporting

confidence: 56%

N-Arylcyano-β-diketiminate Methallyl Nickel Complexes: Synthesis, Adduct Formation, and Reactivity toward Ethylene

et al. 2013

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The syntheses and structures of new bis-N-phenyl-4-cyano-β-diketiminate (1), bis-N-phenyl-2-cyano-β-diketiminate (2), N-phenyl-4-cyano-N-phenyl-2-cyano-β-diketiminate (3), N-phenyl-4-cyano-N-2,6-diisopropylphenyl-β-diketiminate (4), N-phenyl-2-cyano-N-2,6-diisopropylphenyl-β-diketiminate (5), and methallyl nickel complexes [L1Ni(η3-methallyl)] (6), [L2Ni(η3-methallyl)] (7), [L4Ni(η3-methallyl)] (8), and [L5Ni(η3-methallyl)] (9) from the reaction of deprotonated ligands 1/2, 4/5, and methallylnickel chloride dimer are reported. Subsequent reactions of complexes 6–9 with tris(pentafluorophenyl)boron give rise to new adducts [L1Ni(η3-methallyl)]·2B(C6F5)3 (10), [L2Ni(η3-methallyl)]·2B(C6F5)3 (11), [L4Ni(η3-methallyl)]·B(C6F5)3 (12), and [L5Ni(η3-methallyl)]·B(C6F5)3 (13), where B(C6F5)3 is coordinated to the cyano group. New compounds are characterized by NMR, IR, and mass spectrometry techniques, and crystal structures of most compounds are obtained and described. Complexes 6–9, adducts 10–13, and adducts 10–13 with 5 equiv of B(C6F5)3 have been investigated toward ethylene activation. Complexes 6–9 were inactive toward ethylene even at 60 °C, while adducts 10–13 showed reactivity toward ethylene; adding 5 equiv of B(C6F5)3 to adducts 10–13 leads to an increase in reactivity toward ethylene. Adducts 10 and 11 alone and with 5 equiv of B(C6F5)3 catalyze the oligomer formation, while adducts 12 and 13 by the same conditions catalyze the polyethylene formation. Adduct 13 activity is five times higher with respect to 12 at 50 °C and two times higher at 70 °C. The formation of branched moderate molecular weight PE by 12/B(C6F5)3 and 13/B(C6F5)3 is observed.

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Section: Resultssupporting

confidence: 56%

N-Arylcyano-β-diketiminate Methallyl Nickel Complexes: Synthesis, Adduct Formation, and Reactivity toward Ethylene

et al. 2013

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“…In the 19 F NMR spectrum, the three signals at −134.6, −156.2, and −163.6 ppm indicated the attachment of the B(C 6 F 5 ) 3 Lewis acid . The separation of the signals corresponding to the meta and para fluorine substituents by Δ m,p = 7.4 ppm indicated the presence of a distinctly changed tetracoordinated boron, while a separation of the signals corresponding to tricoordinated B(C 6 F 5 ) 3 was Δ m,p = 20.1 ppm, which was similar to the separation of the signals corresponding to the pyridine adduct (C 6 F 5 ) 3 B·NC 5 H 5 of Δ m,p = 7.2 ppm. − The 11 B NMR signal at −10.2 ppm also confirmed the presence of a tetracoordinated boron atom. − These data were consistent with the formation of the [3-cyano-4-[(2,6-bis(3,5-bis(trifluoromethyl)phenyl))imino]pent-2-en-2-olate]tris(pentafluorophenyl)borate-κ 2 N , O (η 3 -CH 2 Ph)Ni II structure of 2 . The adduct was also characterized by FT-IR, and the nitrile group in 1 was attributed to a band at 2200 cm –1 , which shifted by 72 cm –1 toward higher frequencies; this occurred due to the coordination of the nitrile group in 1 with B(C 6 F 5 ) 3 via the nonbonding N lone pair, which reduced the CN repulsions between the carbon and nitrogen atoms and thus made the bond slightly stronger. , The −CF 3 moiety showed a single signal at −63 ppm in the 19 F NMR spectrum.…”

Section: Results and Discussionmentioning

confidence: 61%

Nickel Catalysts Activated by rGO Modified with a Boron Lewis Acid To Produce rGO-Hyperbranched PE Nanocomposites

et al. 2019

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The synthesis, characterization, and ethylene reactivity of a nickel-activated α-cyano-β-ketoiminate complex with B(C 6 F 5 ) 3 is reported. The X-ray diffraction studies of the Ni complex 1 revealed that a weak interaction between the distal aryl rings of the N-terphenyl moiety could be responsible for the low molecular weights and highly branched microstructure of the polyethylene compounds. In addition, a supported single-site Lewis acid based on reduced graphene oxide, rGO-O-B(C 6 F 5 ) 2 , was used, and we studied its ability to activate complex 1 for the generation of polyethylene/ reduced graphene oxide nanocomposites. The supported catalyst rGO-B(C 6 F 5 ) 2 -Ni CN exhibited an ethylene polymerization activity that was approximately 2 times greater than that of the unsupported system. Meanwhile, the microstructure of the polyethylene nanocomposites was analyzed by 13 C NMR, revealing the presence of a low molecular weight and hyperbranched motif due to the presence of sec-butyl groups. These results indicated that the graphene support actively participated in the polymerization process. The morphological examinations of the nanocomposites by TEM revealed the effective exfoliation and good dispersion of rGO in the polymer matrix at the nanoscale level.

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“…In both molecules, the structural parameters around the metal are typical of CpRh(COD) moiety (Table 2). 37,38,45,46 The substituted C5 ring is uniformly η 5 coordinated to the Rh with a Rh-centroid of 1.910( 7) Å [1.912( 7) Å]. The bonds of the Rh atom to the centers of diene systems of the COD ligands are slightly longer with values ranging from 1.985(7) to 2.005(4) Å.…”

Section: Syntheses Of Complexesmentioning

confidence: 99%

Synthesis and reactivity of a cyclopentadienyl-indenyl ligand ring-coupled by a chiral bridge derived from ethyl (S)-(−) lactate

et al. 2013

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In order to prepare a new unsymmetrical chiral ligand, C9H7CH(CH3)CH2C5H5, with an indenyl moiety connected to a cyclopentadienyl unit by a chiral ethylene bridge, we reacted the optically active tosylate 4, derived from ethyl (S)-(-) lactate, with LiCp. The only product resulting from this reaction was an optically active spirocyclopropane 6 obtained with a high diastereoselectivity (81.8% de). We also observed that, when the reduction of the ethyl indene lactate 2 was realized with an excess of LiAlH4 in Et2O under reflux, spirocyclopropane 6 was obtained in high yield with the same diastereoselectivity. When tosylate 4 was reacted with MgCp2, in place of LiCp, ligand 5 was obtained in good yield as a mixture of two double-bond isomers of the Cp unit. Ligand 5 was fully structurally characterized after conversion into transition monometallic complexes such as C9H7CH(CH3)CH2η(5)-C5H4Mo(CO)3Me 7 and C9H7CH(CH3)CH2η(5)-C5H4Rh(COD) 9, in which the indene moiety was kept intact due to the difference in reactivity of the indenyl moiety with respect to the cyclopentadienyl unit. An attempt to prepare a heterobimetallic complex from the sodium indenide salt of 7 and [RhCl(COD)]2, afforded a rhodium cyclopentadienyl complex 9, resulting from a metal exchange reaction with loss of the molybdenum part initially coordinated to the Cp unit, and conservation of the optical purity. An homobimetallic rhodium complex 10 could be prepared by deprotonation of ligand 5 with TlOEt, followed by quenching with [RhCl(COD)]2. The bis-rhodium complex 10 is obtained as a mixture of two diastereoisomers 10a and 10b with respect to the planar chirality of the indenyl ring system, with a good diastereoisomeric excess de = 70%. The structures of both complexes 9 and major (pS)-diastereoisomer 10a were determined by single crystal X-ray diffraction.

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Chemical Behavior of a Pair of (COD)CpRh and −Ir Complexes with Pendant Peripheral −B(C₆F₅)₂Groups

Cited by 14 publications

References 118 publications

N-Arylcyano-β-diketiminate Methallyl Nickel Complexes: Synthesis, Adduct Formation, and Reactivity toward Ethylene

N-Arylcyano-β-diketiminate Methallyl Nickel Complexes: Synthesis, Adduct Formation, and Reactivity toward Ethylene

Nickel Catalysts Activated by rGO Modified with a Boron Lewis Acid To Produce rGO-Hyperbranched PE Nanocomposites

Synthesis and reactivity of a cyclopentadienyl-indenyl ligand ring-coupled by a chiral bridge derived from ethyl (S)-(−) lactate

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