@article {2610,
	title = {HL2[P(1,2-O(2)C(6)H4)(3)] (L = DMSO or DMF): A Convenient Proton Source with a Weakly Basic Phosphorus(V) Anion},
	journal = {Organometallics},
	volume = {28},
	number = {15},
	year = {2009},
	note = {ISI Document Delivery No.: 476PYTimes Cited: 0Cited Reference Count: 114Siu, Paul W. Gates, Derek P.},
	month = {Aug},
	pages = {4491-4499},
	type = {Review},
	abstract = {Treating phosphorus pentachloride with catechol (3 equiv) followed by the addition of dimethylsulfoxide (DMSO) or dimethylformamide (DMF) affords isolable bronsted acids of tris- (o-phenylenedioxy)phosphate anion, [p(1,2-O2C6H4)(3)](-). Specifically. H(DMSO)(2)[P(1,2-O2C6H4)(3)] and H(DMF)(2)[P(1,2-O2C6H4)(3)] have been isolated as crystalline solids. The downfield shifts of the acidic proton in their H-1 NMR spectra are consistent with its expected high acidity. The molecular structures of H(DMSO)(2)[P(1,2-O2C6H4)(3)] and H(DMF)(2)[P(1,2-O2C6H4)(3)] reveal that the protons in each are O-bound by either DMSO (x2) or DMF (x2). The N-H stretching frequency for the Oct(3)NH[P(1,2-O2C6H4)(3)] ((V) over bar (N-H) =3129 cm(-1)) is identical to that observed for trioctylammonium tetrafluoroborate ((v) over bar (N-H) = 3129 cm(-1)), suggesting that the basicity of these two weakly coordinating anions is similar. A preliminary investigation of the effectiveness of H(DMF)(2)[p(1,2-O2C6H4] in the protonolysis of metal-alkyl bonds was undertaken. Treating (dppe) pdMe(2) [dppe = 1,2-bis(diphenylphosphino)ethane] with H(DMF)(2)[P(1,2-O2C6H4)(3)] affords either [(dppe)pd(NCMe)Me][P(1,2-O2C6H4)(3) (1:1 ratio) or [(dppe)pd(NCMe)(2)(][P(1,2-O2C6H4)(3)](2) (1:2 ratio), both of which are structurally characterized.},
	keywords = {ALTERNATING COPOLYMERIZATION, ANIONS, CARBON-MONOXIDE, COORDINATING ANIONS, CRYSTAL-STRUCTURE, DIMETHYL-SULFOXIDE, MIGRATORY INSERTION, MOLECULAR-STRUCTURE, OLEFIN, PALLADIUM(II) COMPLEXES, POLYMERIZATION, SUPERWEAK},
	isbn = {0276-7333},
	url = {<Go to ISI>://000268455900036},
	author = {Siu, P. W. and Gates, D. P.}
}
@article {1263,
	title = {Synthesis and reactivity of zirconium and hafnium complexes incorporating chelating diamido-N-heterocyclic-carbene ligands},
	journal = {Journal of Organometallic Chemistry},
	volume = {690},
	number = {24-25},
	year = {2005},
	note = {ISI Document Delivery No.: 994VFTimes Cited: 36Cited Reference Count: 51},
	month = {Dec},
	pages = {5788-5803},
	type = {Article},
	abstract = {Early transition metal complexes employing a diamido N-heterocyclic carbene (NHC) ligand set (denoted [NCN]) render the centrally disposed NHC moiety stable to dissociation. Aminolysis reactions with the mesityl-substituted ligand precursor ((Mes)[NCN]H-2) and M(NMe2)(4) (M = Zr, Hf) provide bis(amido)-NHC-metal complexes that can be further converted to chloro and alkyl derivatives. Activation of (Mes)[NCN]M(CH3)(2) with [Ph3C][B(C6F5)(4)] yields {(Mes)[NCN]MCH3} {B(C6F5)(4)}, which is surprisingly inactive for the polymerization of 1-hexene. The zirconium cation did, however, show moderate ability to catalytically polymerize ethylene. The hafnium dialkyls are thermally stable with the exception of the diethyl complex, (Mes)[NCN]Hf(CH2CH3)(2), which undergoes P-hydrogen transfer and subsequent C-H bond activation with an ortho-methyl substituent on the mesityl group. The hafnium dialkyl complexes also insert carbon monoxide and substituted isocyanides to yield eta(2)-acyls and eta(2)-iminoacyls, respectively. In some circumstances, further C-C bond coupling occurs to yield enediolates and eneamidolate metallocycles. The molecular structures of (Mes)[NCN]Hf(CH2CHMe2)(2), (Mes)[NCN]Hf(eta(2)-(2,6-Me2C6H3NCCH3)(CH3), (Mes)[NCN]Hf(eta(2)-(2,6-Me2C6H3NCCH3)(2), (Mes)[NCN]Hf(OC(CH3)=C(CH3)NXy), and [(Mes)[NCN]Hf(OC(Bu-i)=C(Bu-i)O)](2) are included. (c) 2005 Elsevier B.V. All rights reserved.},
	keywords = {AMIDO, CARBON-MONOXIDE, CHEMISTRY, DONORS, ETA-2-IMINOACYL, hafnium, LIVING POLYMERIZATION, MIGRATORY INSERTION, N-heterocyclic carbene, OLEFIN, POLYMERIZATION, PROPERTIES, SPECTROSCOPIC, STABLE CARBENES, STRUCTURAL-CHARACTERIZATION, tridentate ligand, ZIRCONIUM, ZIRCONOCENE COMPLEXES},
	isbn = {0022-328X},
	url = {<Go to ISI>://000234058600046},
	author = {Spencer, L. P. and Fryzuk,Michael D.}
}
@article {5076,
	title = {Reaction of [P2N2]Ta=CH2(Me) with ethylene: Synthesis of [P2N2]Ta(C2H4)Et, a neutral species with a beta-agostic ethyl group in equilibrium with an alpha-agostic ethyl group ([P2N2] = PhP(CH2SiMe2NSiMe2CH2)(2)PPh)},
	journal = {Journal of the American Chemical Society},
	volume = {123},
	number = {8},
	year = {2001},
	note = {ISI Document Delivery No.: 405LXTimes Cited: 26Cited Reference Count: 65},
	month = {Feb},
	pages = {1602-1612},
	type = {Article},
	abstract = {The photolysis of [P2N2]TaMe3 ([P2N2] = PhP(CH2SiMe2NSiMe2CH2)(2)PPh) produces [P2N2]Ta=CH2(Me) as the major product. The thermally unstable methylidene complex decomposes in solution in the absence of trapping agents to unidentified products. However, in the presence of ethylene [P2N2]Ta=CH2(Me) is slowly converted to [P2N2]Ta(C2H4)Et, with [P2N2]Ta(C2H4)Me observed as a minor product. A mechanistic study suggests that the formation of [P2N2]Ta(C2H4)Et results from the trapping of [P2N2]TaEt, formed by the migratory insertion of the methylene moiety into the tantalum-methyl bond. The minor product, [P2N2]Ta(C2H4)Me, forms from the decomposition of a tantalacyclobutane resulting from the addition of ethylene to [P2N2]Ta=CH2(Me) and is accompanied by the production of an equivalent of propylene. Pure [P2N2]Ta(C2H4)Et can be synthesized by hydrogenation of [P2N2]TaMe3 in the presence of PMe3, followed by the reaction bf ethylene with the resulting trihydride. Crystallographic and NMR data indicate the presence of a beta -agostic interaction between the ethyl group and tantalum center in [P2N2]Ta(C2H4)Et. Partially deuterated analogues of [P2N2]Ta(C2H4)Et show a large isotopic perturbation of resonance for both the beta -protons and the alpha -protons of the ethyl group, indicative of an equilibrium between a beta -agostic and an a-agostic interaction for the ethyl group in solution. An EXSY spectrum demonstrates that an additional fluxional process occurs that exchanges all of the H-1 environments of the ethyl and ethylene ligands. The mechanism of this exchange is believed to involve the direct transfer of the beta -agostic hydrogen atom from the ethyl group to the ethylene ligand, via the so-called beta -hydrogen transfer process.},
	keywords = {ALKYL ALKENE, C-H, CHAIN PROPAGATION, COMPLEXES, METAL-CARBON BONDS, MIGRATORY INSERTION, MOLECULAR-STRUCTURES, NUCLEAR-MAGNETIC-RESONANCE, OLEFIN, POLYMERIZATION, RAY CRYSTAL-STRUCTURE, TRANSITION-METALS},
	isbn = {0002-7863},
	url = {<Go to ISI>://000167162100008},
	author = {Fryzuk,Michael D. and Johnson, S. A. and Rettig, S. J.}
}
