@article {2528,
	title = {Synthesis and Characterization of a New Thiophene-Bridged Diamidophosphine [NPN] Donor Set and Its Coordination Chemistry with Zirconium(IV): Unexpected Deprotonation-Lithiation Sequence with a Mesitylaminothiophene Precursor},
	journal = {Organometallics},
	volume = {28},
	number = {17},
	year = {2009},
	note = {ISI Document Delivery No.: 489MMTimes Cited: 1Cited Reference Count: 43Menard, Gabriel Jong, Howard Fryzuk, Michael D.},
	month = {Sep},
	pages = {5253-5260},
	type = {Article},
	abstract = {The synthesis and characterization of the thiophene-bridged diamidophosphine proligand [NPN]H-S(2) (2) (where [NPN]H-S(2) = {[N-(2,4,6-Me3C6H2)(3-NH-SC4H2-2-)](2)PPh}) along with several [NPN](ZrX2)-Zr-S (X = NMe2, Cl, I) complexes are presented. The ligand precursor [NPN]H-S(2) was prepared from N-(2,4,6-Me3C6H2)(3-NH-4-Br-SC4H2) (1),(BuLi)-Bu-t, and PhPCl2 in Et2O in 50\% yield; the stereochemistry of the ligand precursor was unexpected and likely resulted from a competitive bromine-lithium exchange and deprotonation sequence with the thiophene starting material I and (BuLi)-Bu-t. A mechanism to rationalize the observed stercochemistry of the product is proposed following deuteration experiments. [NPN]Zr-S(NMe2)(2) (8) can be prepared in 80\% yield by the direct reaction of [NPN]H-S(2) and Zr(NMe2)(4) in toluene. Both [NPN](ZrCl2)-Zr-S (9) and [NPN](ZrI2)-Zr-S (10) are prepared in high yield by the reaction of 8 with excess Me3SiCl or Me3SiI, respectively.},
	keywords = {DIARYLAMIDO-PHOSPHINE-LIGANDS, DIRECTED ORTHO-LITHIATION, END-ON, hafnium, HALOGEN EXCHANGE, lithium, METAL-COMPLEXES, MOLECULAR NITROGEN, ON-BOUND DINITROGEN, PALLADIUM-CATALYZED AMINATION, SIDE-ON},
	isbn = {0276-7333},
	url = {<Go to ISI>://000269424200046},
	author = {Menard, G. and Jong, H. and Fryzuk,Michael D.}
}
@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 {1286,
	title = {Synthesis, characterization, and reactivity of the first hafnium alkyl complex stabilized by amidate ligands},
	journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie},
	volume = {83},
	number = {6-7},
	year = {2005},
	note = {ISI Document Delivery No.: 963UVTimes Cited: 7Cited Reference Count: 20},
	month = {Jun},
	pages = {1037-1042},
	type = {Article},
	abstract = {A photo and thermally stable bis(amidate)-dibenzyl complex of Hf ([(DMP)(NO)(Ph)](2)Hf(CH2Ph)(2)(THF) (2a) was formed as a monosolvated THF adduct in near quantitative yield from Hf(CH2Ph)(4) and N-2,6-dimethylphenyl(phenyl)amide (1). Isomerization between the THF-bound product and the THF-free product can be observed visually by the conversion from a red-orange product at low temperatures to a pale yellow product at high temperatures. Solid-state crystallographic characterization of the orange product confirmed its constitution as a monosolvated species. Kinetic parameters for the exchange of the THF moiety were determined from variable-temperature NMR experiments. The product of the hydrolysis of the Hf dibenzyl species by water was characterized by X-ray crystallography, and was found to be a rare tetrametallic Hf oxo cluster species (3).},
	keywords = {amidate, CHEMISTRY, COORDINATION CHEMISTRY, CRYSTAL, exchange processes, hafnium, HYDROAMINATION, MOLECULAR-STRUCTURE, organometallic, protonolysis, TITANIUM},
	isbn = {0008-4042},
	url = {<Go to ISI>://000231832500064},
	author = {Thomson, R. K. and Patrick, B. O. and Schafer, L. L.}
}
@article {616,
	title = {Reduction of hafnium(IV) complexes in the presence of molecular nitrogen: Attempts to form dinitrogen complexes of the heaviest group 4 element},
	journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie},
	volume = {81},
	number = {11},
	year = {2003},
	note = {ISI Document Delivery No.: 746YXTimes Cited: 10Cited Reference Count: 28},
	month = {Nov},
	pages = {1376-1387},
	type = {Article},
	abstract = {The reaction of [P2N2]Li-2(dioxane)(2) with HfCl4(THF)(2) (where [P2N2] = PhP(CH2SiMe2NSiMe2CH2)(2)PPh) results in the formation of the hafnium dichloride complex [P2N2]HfCl2 (1). The behaviour of 1 as a potential precursor in the generation of a dinitrogen coordination complex is described. Reduction of 1 with potassium-graphite (C8K), under dinitrogen, under a variety of conditions led to a number of products, one of which is the dinuclear derivative with bridging P-phenyl groups that has the general formula {[P2N2]Hf}(2) (2). Reduction of the hafnium diiodide [P2N2]HfI2 (3) - prepared via the reaction of 1 with excess Me3SiI - with C8K results in the formation of ([P2N2]Hf)(2)(mu-eta(2):eta(2)-N-2) (4) as the major product of the reaction, while {[P2N2]Hf}(2) (2) and [P2N2]Hf(C7H8) (5) appear to be minor products. Reaction of 1 with 2 equiv of MeMgCl gives [P2N2]HfMe2 (6), which, upon exposure to an atmosphere of H-2, gives the hafnium tetrahydride {[P2N2]Hf}(2)(m-H)(4) (7).},
	keywords = {COORDINATION CHEMISTRY, DERIVATIVES, DINITROGEN, donor ligands, FLUXIONAL BEHAVIOR, hafnium, hydride, macrocycle, mixed, {ALKYL},
	isbn = {0008-4042},
	url = {<Go to ISI>://000186777600031},
	author = {Fryzuk,Michael D. and Corkin, J. R. and Patrick, B. O.}
}
@article {4348,
	title = {The determination of dissolved zirconium and hafnium from seawater using isotope dilution inductively coupled plasma mass spectrometry},
	journal = {Marine Chemistry},
	volume = {60},
	number = {3-4},
	year = {1998},
	note = {ISI Document Delivery No.: ZR467Times Cited: 23Cited Reference Count: 22},
	month = {Apr},
	pages = {245-255},
	type = {Article},
	abstract = {This paper describes the development of an analytical technique utilizing isotope dilution and inductively coupled plasma mass spectrometry (ICP/MS) to determine the picomolar and femtomolar concentrations of dissolved Zr and Hf found in seawater. Data acquired using this technique are presented to verify the method; in the subarctic North Pacific Zr ranges from 25 to 366 pmol/kg and Hf from 0.20 to 1.02 pmol/kg, with concentrations increasing smoothly with depth. The chelating ion-exchange resin, Chelex-100, was found to be suitable for the extraction/concentration step required for the determination of dissolved Zr and Hf in seawater using isotope dilution analysis. The extraction was optimized for pH, flow rate, resin volume, elution volume, and the time required for isotope equilibration. The isotope ratios Zr-91/Zr-90 and Hf-178/Hf-177 were measured using flow injection ICP/MS. The detection limits for a one litre sample are 0.21 and 0.03 pmol/kg for Zr and Hf, respectively. The analytical precision (Is) of the technique improves with increasing concentration and varies from 7\% at 42 pmol/kg to 2.5\% at 280 pmol/kg for Zr and from 22\% at 0.28 pmol/kg to 9\% at 1.4 pmol/kg for Hf. (C) 1998 Elsevier Science B.V.},
	keywords = {aluminum, ATLANTIC, ATOMIC-ABSORPTION SPECTROMETRY, Chelex-100, hafnium, ICP-MS, OCEAN, SEA-WATER, SEAWATER, trace metals, TRACE-METALS, ZIRCONIUM},
	isbn = {0304-4203},
	url = {<Go to ISI>://000073979800008},
	author = {McKelvey, B. A. and Orians, K. J.}
}
