@article {2627,
	title = {Noninnocent Behavior of Ancillary Ligands: Apparent Trans Coupling of a Saturated N-Heterocyclic Carbene Unit with an Ethyl Ligand Mediated by Nickel},
	journal = {Journal of the American Chemical Society},
	volume = {131},
	number = {30},
	year = {2009},
	note = {ISI Document Delivery No.: 479FFTimes Cited: 6Cited Reference Count: 26Steinke, Tobias Shaw, Bryan K. Jong, Howard Patrick, Brian O. Fryzuk, Michael D. Green, Jennifer C.},
	month = {Aug},
	pages = {10461-10466},
	type = {Article},
	abstract = {Oxidative addition of the tridentate N-heterocyclic carbene (NHC) diphosphine ligand precursor ([PCP]H)PF6 (1) {[PCP] = o-(Pr2PC6H4)-Pr-i(NC3H4N)o-(C6H4PPr2)-Pr-i} to Ni(COD)(2) results in the formation of the nickel(II) hydride complex ([PCP]NiH)PF6 (2). This hydride undergoes a rapid reaction with ethylene to generate a nickel(O) complex in which an ethyl group has been transferred to the carbene carbon of the original NHC-diphosphine ligand. If the first intermediate is the anticipated square-planar nickel(II) ethyl species, then the formation of the product would require a process that involves a trans C-C coupling of the NHC carbon and a presumed Ni-ethyl intermediate. Deuterium-labeling studies provide evidence for migratory insertion of the added ethylene into the Ni-H bond rather than into the Ni-catene linkage; this is based on the observed deuterium scrambling, which requires reversible P-elimination, alkene rotation, and hydride readdition. However, density functional theory studies suggest that a key intermediate is an agostic ethyl species that has the Ni-C bond cis to the NHC unit. A possible transition state containing two cis-disposed carbon moieties was also identified. Such a process represents a new pathway for catalyst deactivation involving NHC-based metal complexes.},
	keywords = {ACTIVATION, CHEMISTRY, COMPLEXES, MECHANISM, MIGRATORY INSERTION, NHC, ORGANOMETALLIC CATALYSIS, palladium, REDUCTIVE ELIMINATION, ruthenium},
	isbn = {0002-7863},
	url = {<Go to ISI>://000268644400040},
	author = {Steinke, T. and Shaw, B. K. and Jong, H. and Patrick, B. O. and Fryzuk,Michael D. and Green, J. C.}
}
@article {936,
	title = {Iodide effects in transition metal catalyzed reactions},
	journal = {Dalton Transactions},
	number = {21},
	year = {2004},
	note = {ISI Document Delivery No.: 865WTTimes Cited: 16Cited Reference Count: 153},
	pages = {3409-3419},
	type = {Review},
	abstract = {The unique properties of I- allow it to be involved in several different ways in reactions catalyzed by the late transition metals: in the oxidative addition, the migration, and the coupling/reductive elimination steps, as well as in substrate activation. Most steps are accelerated by I- (for example through an increased nucleophilicity of the metal center), but some are retarded, because a coordination site is blocked. The "soft" iodide ligand binds more strongly to soft metals (low oxidation state, electron rich, and polarizable) such as the later and heavier transition metals, than do the other halides, or N- and O-centered ligands. Hence in a catalytic cycle that includes the metal in a formally low oxidation state there will be less tendency for the metal to precipitate ( and be removed from the cycle) in the presence of I- than most other ligands. Iodide is a good nucleophile and is also easily and reversibly oxidized to I-2. In addition, I- can play key roles in purely organic reactions that occur as part of a catalytic cycle. Thus to understand the function of iodide requires careful analysis, since two or sometimes more effects occur in different steps of one single cycle. Each of these topics is illustrated with examples of the influence of iodide from homogeneous catalytic reactions in the literature: methanol carbonylation to acetic acid and related reactions; CO hydrogenation; imine hydrogenation; and C-C and C-N coupling reactions. General features are summarised in the Conclusions.},
	keywords = {ASYMMETRIC HYDROGENATION, BETA-KETO-ESTERS, CARBON-MONOXIDE, DETECT SPECIES PRESENT, HIGHLY ENANTIOSELECTIVE HYDROGENATION, METHANOL CARBONYLATION, OXIDATIVE-ADDITION, PARAHYDROGEN INDUCED, polarization, QUATERNARY ONIUM SALTS, REDUCTIVE ELIMINATION},
	isbn = {1477-9226},
	url = {<Go to ISI>://000224735600001},
	author = {Maitlis, P. M. and Haynes, A. and James, Brian R. and Catellani, M. and Chiusoli, G. P.}
}
@article {706,
	title = {Thermal activation of hydrocarbon C-H bonds by Cp*M(NO) complexes of molybdenum and tungsten},
	journal = {Accounts of Chemical Research},
	volume = {36},
	number = {4},
	year = {2003},
	note = {ISI Document Delivery No.: 669GJTimes Cited: 54Cited Reference Count: 36},
	month = {Apr},
	pages = {223-233},
	type = {Review},
	abstract = {Gentle thermolysis of appropriate Cp*M(NO)(hydrocarbyl)(2) complexes (Cp* = eta(5)-C5Me5) of molybdenum and tungsten results in loss of hydrocarbon and the transient formation of 16-electron Cp*M(NO)-containing complexes such as Cp*M(NO)(alkylidene), Cp*M(NO)(eta(2)-benzyne), Cp*M(NO)(eta(2)-acetylene), and Cp*M(NO)(eta(2)-allene) (M = Mo, W). These intermediates effect the single, double, or triple activation of hydrocarbon C-H bonds intermolecularly, the first step of these activations being the reverse of the transformations by which they were generated. This Account summarizes the various types of C-H activations that have been effected with these nitrosyl complexes and also describes the results of kinetic, mechanistic, and theoretical investigations of these processes.},
	keywords = {ALKANES, ALKYLIDENE COMPLEXES, ARENES, CHEMISTRY, INTERMEDIATE, NITROSYL, REACTIVITY, REDUCTIVE ELIMINATION, THERMOLYSIS, TRANSITION-METAL BONDS},
	isbn = {0001-4842},
	url = {<Go to ISI>://000182343300001},
	author = {Pamplin, C. B. and Legzdins,Peter}
}
@article {4995,
	title = {Intermolecular C-H activation of hydrocarbons by tungsten alkylidene complexes: An experimental and computational mechanistic study},
	journal = {Organometallics},
	volume = {20},
	number = {23},
	year = {2001},
	note = {ISI Document Delivery No.: 493VBTimes Cited: 17Cited Reference Count: 65},
	month = {Nov},
	pages = {4939-4955},
	type = {Article},
	abstract = {Cp*W(NO)(CH2CMe3)(2) (1) and Cp*W(NO)(CH2CMe3)(CH2C6H5) (2) under moderate conditions (70 degreesC, 40 h) generate the reactive complexes Cp*W(NO)(=CHCMe3) (A) and Cp*W(NO)(=CHC6H5) (B), respectively, which activate hydrocarbon solvents via the addition of C-H across the M=C bond. The alpha -deuterated derivative Cp*W(NO)(CD2CMe3)(2) (1-d(4)) undergoes intramolecular H/D exchange within the neopentyl ligands, consistent with the formation of a-neopentane complexes prior to neopentane elimination. The thermolysis of 1 in a 1:1 molar mixture of tetramethylsilane-h(12) and tetramethylsilane-d(12) (70 degreesC, 40 h) yields an intermolecular KIE of 1.07(4):1. Thermolysis of I and 2 in 1:1 benzene/benzene-d(6) yields intermolecular KIEs of 1.03(5):1 and 1.17(19):1, respectively. The KIE values are inconsistent with rate-determining C-H bond addition to the M=C linkage and indicate that coordination of the substrate to the metal center is the discriminating factor in alkane and arene intermolecular competitions. The complexes Cp*W(NO)(CH2CMe3)(C6D5) (5-d(5)) and CP*W(NO)(CH2C6H5)(C6D5) (6-d(5)) convert to the respective H/D scrambled products Cp*W(NO)(CHDsynCMe3)(C6D4H1) (5{\textquoteright}-d(5)) and Cp*W(NO)(CHDsynC6H5)(C6D4H1) (6{\textquoteright}-d(5)) under thermolytic conditions, consistent with the occurrence of reversible aromatic sp(2) C-H bond cleavage. The results suggest that the previously reported discrimination between the aryl and benzyl products of toluene activation by A and B originates from coordination of toluene to the metal center in two distinct modes. Supporting DFT calculations on the activation of toluene by CpW(NO)(=CH2) (C) indicate that aromatic sp(2) C-H bond activation proceeds through a pi -arene complex, while benzylic sp(3) C-H bond activation proceeds through a eta (2)(C,H),sigma -phenylmethane complex. The principal factor behind the preferential formation of the aryl products appears to be the relative energies of formation of these intermediates.},
	keywords = {BOND ACTIVATION, EFFECTIVE CORE POTENTIALS, EXCHANGE, METAL-ALKANE COMPLEXES, METHANE, METHYL-HYDRIDE, MOLECULAR CALCULATIONS, MOLYBDENUM, ORGANOMETALLIC NITROSYL CHEMISTRY, REDUCTIVE ELIMINATION},
	isbn = {0276-7333},
	url = {<Go to ISI>://000172243200026},
	author = {Adams, C. S. and Legzdins,Peter and McNeil, W. S.}
}
@article {4669,
	title = {A computational study of two-state conformational changes in 16-electron [CpW(NO)(L)] complexes (L = PH3, CO, CH2, HCCH, H2CCH2)},
	journal = {Chemistry-a European Journal},
	volume = {5},
	number = {5},
	year = {1999},
	note = {ISI Document Delivery No.: 194UQTimes Cited: 20Cited Reference Count: 52},
	month = {May},
	pages = {1598-1608},
	type = {Article},
	abstract = {Electronically and coordinatively unsaturated [Cp*W(NO)(L)] complexes have been postulated as intermediates in several related systems. Model [CpW(NO)(L)] compounds (L= PH3, CO, CH2, H2CCH2, HCCH) have been investigated theoretically by means of density functional theory computational techniques. The structural parameters calculated for saturated [CpW(NO)(PH,)(L)] complexes are in good agreement with the solid-state molecular structures determined crystallographically for the corresponding [Cp*W(NO)(PMe3)(L)] compounds. The 16-electron, singlet [CpW(NO)(L)] species have geometries comparable to those of the same fragment in the phosphine adducts and include a highly pyramidal conformation at W. The energy of the triplet spin state is calculated to be close to or even lower than that of the singlet state for these unsaturated compounds, and depends largely on the pi-bonding capabilities of L (Delta Es-t=Delta E-t-Delta E-s = - 3.3 kcalmol(-1) (PH3), + 2.8 (CO), + 2.4 (CH2), +6.3 (H2CCH2), -2.3 (HCCH)). The optimization of partially constrained structures in both spin states allows for a conformational analysis of the [CpW(NO)(L)] species. The inversion of the conformation of the pyramidal singlet [CpW(NO)(L)] complexes via the planar-at-W triplet species (two-state pathway) is calculated to be competitive with the equivalent process solely along the singlet spin hypersurface. Rotation of the W-CH, bond in the singlet carbene species is also found to proceed more readily via a two-state pathway. The preferred alkyne conformation, the unusually stable triplet states, and the strong W-to-L sc-donation observed in these systems may all be rationalized by the relatively high energies of the occupied orbitals of the formally WO compounds.},
	keywords = {ACTIVATION, CROSSOVER, density functional calculations, H BOND, LIGAND, ligand effects, MOLECULAR CALCULATIONS, ORGANOMETALLIC NITROSYL CHEMISTRY, OXIDATIVE ADDITION, pi interactions, PIANO-STOOL COMPLEXES, REACTIVITY, REDUCTIVE ELIMINATION, SPIN, SPIN-STATE, TUNGSTEN},
	isbn = {0947-6539},
	url = {<Go to ISI>://000080212600026},
	author = {Smith, K. M. and Poli, R. and Legzdins,Peter}
}
@article {7015,
	title = {THERMAL AND PHOTOCHEMICAL-TRANSFORMATIONS OF ORGANOIRIDIUM PHOSPHIDE COMPLEXES - MECHANISTIC STUDIES ON CARBON PHOSPHORUS BOND FORMATION TO GENERATE CYCLOMETALATED HYDRIDE COMPLEXES BY ALPHA-HYDRIDE ABSTRACTION},
	journal = {Journal of the American Chemical Society},
	volume = {113},
	number = {23},
	year = {1991},
	note = {ISI Document Delivery No.: GP037Times Cited: 28Cited Reference Count: 62},
	month = {Nov},
	pages = {8724-8736},
	type = {Article},
	abstract = {{The thermal and photolytic transformations of a series of methyliridium(III) phosphide complexes are described. Complexes of the formula Ir(CH3)PR2[N(SiMe2CH2PPh2)2] (R = Ph, Me) rearrange thermally to generate the corresponding cyclometalated derivatives fac-Ir(eta-2-CH2PR2)H[N(SiMe2CH2PPh2)2]; continued thermolysis results in the formation of the iridium(I) phosphine complexes Ir(PMeR2)[N(SiMe2CH2PPh2)2]. Under photolytic conditions the phosphide derivatives rearrange directly to the phosphine complexes with no observable intermediates. The phenylphosphide complex Ir(CH3)PHPh[N-(SiMe2CH2PPh2)2] rearranges directly to the phosphine derivative Ir(PHPhMe)[N(SiMe2CH2PPh2)2] both thermally and photolytically with no observable intermediates. Crystals of lr(CH3)PPh2[N(SiMe2CH2PPh2)2] are monoclinic with a = 13.506 (3) angstrom},
	keywords = {ACTIVATION, C-H, CHEMISTRY, CRYSTAL-STRUCTURE, DERIVATIVES, HYDROGEN-BONDS, IRIDIUM, LIGAND, REACTIVITY, REDUCTIVE ELIMINATION},
	isbn = {0002-7863},
	url = {<Go to ISI>://A1991GP03700020},
	author = {Fryzuk,Michael D. and Joshi, K. and Chadha, R. K. and Rettig, S. J.}
}
