Oxidative Addition of a Dinuclear and Divalent Vanadium Hydride to an Olefin C−H Bond, Leading to Catalytic Hydrogenation

Abstract

The dinuclear and divalent hydride complex {[(Me3Si)NP(Ph)2C(H)P(Ph)2N(SiMe3)]V}2(μ-H)2 (1) performs oxidative addition to the styrene β-C−H bond, affording the novel dinuclear trivalent vanadium complex {[(Me3Si)NP(Ph)2C(H)P(Ph)2N(SiMe3)]V}2(H)(μ-H)2(μ,η1:η2-CHCHPh) (2). Room-temperature hydrogenolysis re-formed 1 and ethylbenzene in catalytic fashion. Reaction of 1 with ethylene afforded instead the mixed-valence {[(Me3Si)NP(Ph)2C(H)P(Ph)2 N(SiMe3)]V}2(μ-H)3 (3) and a mixture of 2-butene and 3-methyl-1,4-pentadiene.

Well-defined vanadium complexes as the catalysts for olefin polymerization

“…Many tridentate or polydentate ligands have been applied to stabilize the active vanadium complexes [11,52,[85][86][87][88][89][90][91][92][93][94][95][96][97][98][99]. For example, vanadium complexes bearing tridentate bis(benzimidazole) amine ligands reported by Gibson's group showed high activity toward olefin polymerization [87].…”

Main-group and transition-metal complexes of bis(phosphinimino)methanides

“…The treatment of 70 with styrene produced another paramagnetic complex, [{CH(PPh 2 NSiMe 3 ) 2 }V] 2 (H)(m-H) 2 -(m,Z 1 :Z 2 -CHCHPh)] (73), which in the solid state revealed two vanadium atoms differently bonded to a bis(phosphinimino)methanide ligand. 77 One vanadium atom was surrounded by the ligand that used central bridgehead carbon and the two iminium nitrogens as donors. In this case the ligand adopted the usual tridentate geometry with the V-N-P-C plane folded along the V-C vector.…”

“…The chromium complex of the dianionic bis(phosphinimino)methanediide ligand [Cr{m-C(PPh 2 NSiMe 3 ) 2 }] 2 (76) was first synthesized by Cavell and co-workers by treating [CrCl 2 (THF) 2 ] with [Li 2 {C(PPh 2 NSiMe 3 ) 2 }] (3a), via elimination of 2 mol of LiCl, as a paramagnetic, red, air-sensitive crystalline solid (Scheme 21). 79 A lithium chloride incorporated tetranuclear complex [Cr 2 (m-Cl) 2 {m-C(PPh 2 NSiMe 3 ) 2 }-(LiCl)(THF) 2 ] 2 (77) was prepared in good yield by the reaction of 0.5 mol equivalents of the ligand with the metal precursor [CrCl 2 (THF) 2 ] (Scheme 21). The magnetic moments of 76 (2.76 m B ) and 77 (6.28 m B ) were considerably low for the total number of unpaired electrons of Cr(II) due to interaction between the metals.…”

Synthesis, Structure, Reactivity, and Catalytic Activity of C,N‐ and C,N,N‐Orthopalladated Iminophosphoranes

“…Complex 11 does not react with Tl(acac) under the usual experimental conditions (room temperature, 1:1 molar ratio), and unchanged 11 can be recovered at the end of the reaction. However, the reaction of 11 with AgClO 4 and Ph 2 PCH 2 PPh 2 (dppm), Ph 2 PCH 2 CH 2 PPh 2 (dppe), 1,10-phenanthroline (phen) or 2,2Ј-bipyridine (bipy) (1:1:1 molar ratio) in acetone gives complexes of stoichiometry (15), dppe (16), bipy (17), phen (18)], in keeping with their elemental analyses and mass spectra. The IR spectra of 15-18 show the absorption due to the ν PN stretch in the range 1330-1340 cm -1 , thereby suggesting that the Pd-N-(imine) bond is still present.…”

“…The best reaction solvent for this type of process was found to be DMF. In spite of its similarity, very poor yields were obtained when N,Ndimethylacetamide (DMA) was used (entries 1-4 vs. entries [15][16][17][18], and the reaction was completely inhibited in NMP (N-methylpyrrolidinone). A comparison of the different catalysts shows that complexes 1 and 4 give better conversions than complexes 11 or 13, and this fact could be related to the presence of the highly stable terdentate ligand [C 6 H 4 -2-PPh 2 =N-C(O)-2-NC 5 H 4 -κ-C,N,N] in 11 and 13 (see below).…”