Borate, tetrakis methyl

C30H24O4P2W, Tungsten(O), tetracarbonyl 1,2-bis(diphenylphosphino)ethane -, 34 108 C32Hi2BF24Na, Borate, tetrakis(3,5-bis(trifluoro-methyl)phenyl)-, sodium salt, 34 5 C32H29FeNP2, Iron(II), cyano( ) -cyclopentadie-nyl)-l,2-bis(diphenylphosphino)ethane-, 34 161... 

It is generally adopted that the catalytically active species in the metallocene-catalysed polymerization is a 14-electron cation. As an example, the mechanism of activation of an unbridged zirconocene catalyst is presented in Fig. 9.5-4, top. In the first two steps the activation by MAO, resulting in the 14-electron cation, is shown. The same cation can be generated by N,N -dimethylanilinium-tetrakis(pentafluorophenyl)borate and methylated metallocenes. As side-products methane and an amine are formed. TiBA can also be involved in the activation, which is not shown in Fig. 9.5-4, bottom. On the other hand, TiBA acts as a scavenger in the polymerization. The above-mentioned reactions take place in the absence of the monomer and are performed before the catalyst is used in the polymerization process. 

RuAuFjOPjCjjHgj, Ruthenium(l-t-), car-bonyldi-n-hydrido-tris(triphenylphos-phine) (triphenylphosphine)gold]-, hexafluorophosphate(l—), 29 281 RuAujFgPgCgoHjg, Ruthenium(l-t-), tri-p-hydrido-tris(triphenylphos-phine)bis[(triphenylphosphine)gold]-, hexafluorophosphate(I -), 29 286 RuBjNgCjoHjg, Ruthenium(II), (V-1,5-cyclooctadiene)tetrakis(methyl-hydrazine)-, bis(tetraphenyl-borate(l—)), 26 74... 

Ligand abbreviations (6-Mepy)(py)2tren and (6-Mepy)2(py)tren = tris[4-[(6-/ )-2-pyridyl]-3-aza-6-butenyl]amme, R = H or CH3 HB(pz)3 = hydro-tris(pyrazolyl)borate paptH = 2-(2-pyridylamino)-4-(2-pyridyl)thiazole phenmethoxa = 3-[2-(l,10-phenanthrolyl)]-5-methyl-l,2,4-oxadiazole pyimH = 2-(2 -pyridyl)itnidazole pybimH = 2-(2 -pyridyl)benzimidazole ppa = JV -(2-pyridylmethyl)picolineamidine tpmbn = tetrakis(2-pyridylmcthyl)-meso-2,3-butane-diamine tppn = tetrakis-(2-pyridylmethyl)-l-methyl-l,2-propanediainine tpchxn = tetrakis(2-pyridylmethyl)-tra s-l,2-cyclohexanediamine biz = 2,2 -bi-1,4,5,6-tetrahydropyrimidine. 

The Lewis acidity and reactivity of these alkyl aluminum cocatalysts and activators with Lewis basic polar monomers such as acrylates make them impractical components in the copolymerization of ethylene with acrylates. To address this shortcoming, Brookhart et al. developed well-defined cationic species such as that shown in Fig. 2, in which the counterion (not illustrated) was the now-ubiquitous fluorinated arylborate family [34] such as tetrakis(pentaflurophenyl)borate. At very low methyl acrylate levels the nickel catalysts gave linear copolymers but with near-zero levels of acrylate incorporation. 

SYNTHESIS OF (45, 55)-[(f -l,5-CYCLOOCTADIENE)- 2-(2-PHEN YL-5-METHYL, 5-DIHYDRO-OXAZOL-4-YL)-1,3-DIPHENYL-2-DIPHENYLPHOSPHINITE-PROPANE IRIDIUM(I)]-TETRAKIS[3,5-BIS(TRIFLUOROMETHYL)PHENYL]BORATE... 

Cyclooctadiene)- 2-(2-phenyl-5-methyl-4,5-dihydro-oxazol-4-yl)-l,3-diphenyl-2-diphenylphosphimte-propane mdium(l)]-tetrakis[3,5-bis(tri-fluoromethyl)phenyl]borate (1.72mg, l.Opmol). The catalyst is available from Strem Chemicals, Inc. (catalogue no. 77-5020). 

HGURE 8.1. Formal potentials of redox species in W, NB and DCE versus NHE. Abbreviations ZnTMPyP = zinc tetra-7V-methyl-4-pyridium porphyrin, DcMFc = decamethylfetrocene, TCNQ = 7,7,8,8-tetracyanoquinodimethane, DiMFc = dimethylferrocene, Fc = ferrocene, RuTPP(py)2 = bisfpyridine) meso-tetraphenylporphyrinato ruthenium(II), SnPc2 = tin(IV) diphthalocyanine, LuPc2 = lutetium(in) di]dithalo-cyanine, DiFcET = diferrocenylethane, TAA = tris(4-methoxyphenyl)amine, TPB = tetraphenylborate, TBrPA = tris(4-bromophenyl)amine, TCIPB = tetrakis(4-chlorophenyl)borate. The data is from Ref. [26], except where otherwise noted Ref. [6], Ref. [29], Ref. [30], Ref. [31], Ref. [32]. Reprinted from Ref. [28], with permission from the Polarographic Society of Japan. 

Silylium ions stabilized by Si-X-Si three-center bonds (X = halogen or hydrogen) have been synthesized by the reaction of the corresponding l-tris(trimethylsilyl)methyl-2,3-bis(trimethylsilyl)-l-silacyclopropene derivative with triethylsilylbenzenium tetrakis(pentaflourophenyl)borate <2004CL530>. 

Dialkyl metallocenes and other dialkyl Group 4 transition metal complexes are useful as precatalysts in combination with co-catalysts such as tris(perfluoro-aryl)boranes or tetrakis(periluoroaryl)borate salts [18]. Recently, an expedient procedure for the production of dimethyl metallocenes and Cp-amido dimethyl metal complexes in high yields and purity has been reported. The direct synthesis of Group 4 dimethylmetallocenes [19] consists of the one-pot reaction between the r-ligand, a 2-fold excess of MeLi, and MtCU. This simple method produces the dimethylated complexes in higher overall yield, and saves on reaction time and solvents, compared to the classic two-step route, which consists in the synthesis of the metallocene dichloride followed by its methylation with 2 equiv. MeLi. 

Brookhart s catalysts Mixture of [N,N -(1,2-dimethyl-1,2-ethanediylidene)bis[2,6-bis(1-methylethyl)benzenamine-KappaA/]] methyl[1,1 -oxybis[ethane]]palladium(1 +) tetrakis[3,5-bis(trifluoromethyl)phenyl] borate(1") and the same complex but with "(acetonitrile)" group instead of "[1,1 -oxybis[ethane]j" group. 

While all attempts to avoid formation of the hydride cluster or to convert it back to a catalytically active species failed, the solution to the deactivation problem turned out to be as simple as surprising. Exchange of the counterion from PF to tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BAtp) strongly increased conversion (Scheme 5). Using catalyst 9 with BArp as the counterion, several thousand turnovers could be obtained in the hydrogenation of frani -methyl stilbene 10 under optimized conditions. 

The sodium salt of the optically active tetrakis(4,5,6,7-tetrahydro-7,8,8-trimethyl-2//-4,7 methanoindazolyl)borate, Na(pz-jpcamph-j was preparecl by the reaction of 4,5,6,7-tetrahydro-7, 8,8-trimethyl-2//-4,7-methanoindazole with NaBFLp Analogously the sodium salt of hydrotris((—)-3(5)-methyl-l-phenylethy-... 

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