Nickel triethylphosphin

Bis(triethylphosphine)platinum[l,8]naphthalene 56 undergoes diphenylacetylene insertion and reductive elimination to yield 1,2-diphenylacenaphthalene (Equation 18) <2005JA13494>. As noted in Equation (11), an analogous zirconacyclobutene complex inserts alkyne only upon prior transmetallation to nickel. 

Although the triethylphosphine complexes of nickel(H) may not necessarily represent optimum examples of catalysts,(12)(13) they allowed us access to the key intermediate, viz., tHe siryl-methyl-nickel complexes such as la and b. Any catalytic cycle... 

In 1996, Naka et al. described the synthesis of silicon-carbon unsaturated compounds via a nickel-catalyzed reaction <1996OM1101>. 3,4-Benzo-l,l,2,2-tetraethyl-l,2-disilacyclobut-3-ene 106 with bis(trimethylsilyl)acety-lene 107 in presence of a catalytic amount of tetrakis(triethylphosphine)nickel(0) in a sealed glass tube at 150 °C for 24h gave 5,6-benzo-l,l,4,4-tetraethyl-2,3-bis(trimethylsilyl)-l,4-disilacyclohex-2,5-diene 108, 4,5-benzo-l,l,3,3-tetraethyl-2-[bis(trimethylsilyl)methylene]-l,3-disilacyclopent-4-ene 109, 5,5,6,6,1 l,12,12-octaethyl-5,6,ll,12-tet a-silanaphthacene 110, and l,l -bis(3,4-benzo-2,2,5,5-tetraethyl-2,5-disilacyclopent-3-enylidene) 110, in 10%, 21%, 41%, and 9% yields (Scheme 13). 

The derivatives with triethylphosphine and ethylene, styrene, stilbene, and methylstyrene have been prepared from bispentan-2,4-dionatonickel and alkylaluminum compounds in the presence of the phosphine and the olefin 200). The oxidation number of nickel in these compounds is controversial because the compounds can be considered to be either trico-ordinated nickel(O) derivatives (1) or square planar nickel(II) derivatives (2). 

Dichlorobis(triethylphosphine)nickel(II) is an effective catalyst for the reaction of symmetrical tetramethyldisilane with unsaturated hydrocarbons (237). A hydronickel complex was postulated as being involved in the reaction, although the mechanism may involve the intermediacy of a dimethylsilylene compound formed by Si—Si bond cleavage rather than the silyl-nickel bond being formed by Si—H bond cleavage. The complex was an effective catalyst for formation of the... 

Stereoselective synthesis of organometallic complexes has been achieved in the oxidative addition of aryl halides to triethylphosphine nickel(O) complexes, leading to the exclusive formation of trans-2ivy nickel(II) halide complexes [383]. Electron-transfer reactions on the Fe of cis- and ra/w-[7/-C5H5Fe(CO)SR]2 occur stereospecifically with no stereoisomerization on changing the oxidation state of the Fe [384,385]. In the electrochlorination of a ligand (R) of the //-C5H5Fe(CO)R complex, the stereochemistry is retained [386]. 

ULLMANN REACTION trans-Bromo-o-tolylbis(triethylphosphine)nickeL... 

When tetrakis(triethylphosphine)nickel is added to a solution of the arachno-carbaborane l,3-B7C2HnMe2, one molecule of H2 is evolved and red crystals of Ni(B7C2H9Me2)(PEt3)2 (14) are deposited. A number of other... 

Stoichiometric reaction of tetrakis(triethylphosphine)nickel(0) with silacyclopropene (64) gave nickelasilacyclobutene (65) in quantitative yield (Equation (22)). The structure was supported by spectroscopic analysis and subsequent chemical reactivity <86JA7417,890M2050). 

The analogous bis(triethylphosphine)palladium complex also shows a singlet at 8 -71-0. (127) The nickel complex [318] of (+)-perfluoro(2,3-diphenylbutane-2,3-diol), like the free diol (both meso and dl isomers) shows five inequivalent aromatic fluorines, due to hindered rotation of the C6F ring. Since the inequivalence persists in the complexes, the hindrance cannot be due to hydrogen bonding. (174)... 

Alkylation of dibromobis(triethylphosphine)nickel(II) has been conducted stepwise using arylmagnesium bromide and methyllithium, leading to unsymmetrical /ra/7.y-aryl(methyl)nickel complex 5 [24], which further reacts with l,2-bis(dimethyl-phosphino)ethane (dmpe) to give ra-aryl(methyl)nickel complex 6 (eq (15)) [25]. 

Like other cyclic compounds having a cis-azo linkage, benzo[c]cinnoline forms fairly stable complexes with many transition metal salts.These all have a 1 1 ligand metal ratio except in the case of palladium(II) chloride, where a 2 1 complex has been isolated.Benzo[c]cinnoline 5-oxide also gives 2 1 complexes with palladium(ll) chloride and with silver nitrate. " A nickel(O) complex, Ni(PEt3)2(benzo[c]cinnoline)2, has been obtained by reaction with biscyclooctadiene nickel and triethylphosphine in hexane. " ... 

Bis(A V-diethyldiselenocarbamato)nickel(II) (0.54 g 1.0 mmole) is suspended in 75 mL acetone. Dichlorobis(triethylphosphine)nickel(II) (0.37 g 1.0 mmole) is dissolved in 25 mL acetone. While stirring the Ni(Se2CNEt2)2 suspension, the Ni(PEt3)2Cl2 solution is added. The suspension slowly turns deep red. Stirring for about 30 minutes gives a dark-red solution. The volume is reduced by evaporation to 50 mL. Petroleum ether (100 mL) is added and the solution stored in the freezer for several hours. Very dark crystals are obtained which are filtered, washed with petroleum ether, and dried under vacuum. Yield - 0.75 g, 82%, mp, 92-5°. (At 80°, the color turns darker until at 90°, it is almost black. At 92°, the crystals melt giving a dark-red liquid.)13... 

ClIrP3Ci7H4i, Iridium, chloro(T 2-cyclooc-tene)tris(trimethylphosphine)-, 21 102 ClIrP4Ci2H32, Iridium(l + ), bis[ 1,2-ethanediyl-bis(dimethylphosphine)]-, chloride, 21 100 ClNNiPSe2C H25, Nickel(II), chloro(N -die-thyldiselenocarbamato)(triethylphosphine)-, 21 9... 

NiClNPSe2C,iH25, Nickel(Il), chloto(Al V-die-thyldiselenocarbamato)(triethylphosphine)-, 21 9... 

Nickel(0)-iDreaction with a urea or a thiourea, which may be mono-N- or di-A, A"-substituted. o-Iodobenzonitrile behaves similarly. Nickel(II) chloride is complexed with triethylphosphine, and the reaction needs a temperature of about 60 °C. 

NiB N C.gHi,), Nickel(D), dibromo-bis(3,3, 3 -phosphinidyne-(tripropionitrile)-, 22 115 NiCINPSejCnHa, Nickel(ll), chloro(JV,JV-di-ethyldiselenocarbamato)-(triethylphosphine)-, 21 9 NiCljN CigHj, Nickel(II), dichloro-... 

A recently reported cyclodimerization reaction of butadiene is the formation of 2-methylenevinylcyclopentane 170 171>. The reaction is catalyzed most effectively by rra/jj-bis (triethylphosphine)chloro-(o-tolyl)nickel in the presence of alcohol. It is interesting that negligible amounts of cyclooctadiene and cyclo-dodecatriene are formed with this catalyst. 

The salt is prepared by reaction of triethylphosphine (2 moles) with nickel(II) bromide. 

Reagents. The lithium metal, containing a maximum of 0.05% sodium, was obtained from the Lithium Corporation of America. Bis(l,5-cycloocta-diene)nickel [(Cod)2Ni)] was prepared by a modification of a known procedure (13). This complex was used to prepare tetrakis(triethylphosphine)nickel [(Et3P)4Ni]. Tetraphenylcyclobutadienenickel(II) bromide dimer was synthesized from stilbene-free diphenylacetylene (14). 

The formation of metallasilacyclobutene has been proposed in the transition metal catalyzed reaction of silacyclopropenes with an acetylene [86,88-93]. Ishikawa et al. [97] suggested the presence of nickelasilacyclobutenes from C-, Si-, and P-nmr data. Irradiation of a solution of 2-mesityl-2(phenyl-ethynyl)-l,l,l,3,3,3-haxamethyltrisilane in hexane at room temperature gave silacyclopropene and then reacted with tetrakis(triethylphosphine)nickel(0) to... 

P2B02PtC4oH57, Platinum(II). (3-methoxy-3-oxo-KO-propyl-KC )bis(triethylphos-phine)-, tetraphenylborate(l-), 26 138 P2BPtC44Ht3, Platinum(ll), (q -cyclo-octene)bis(triethylphosphine)-, tetra-phenylborate( 1 —), 26 139 P2C4H 4, Phosphine, 12-ethanediylbis(di-methyl-, nickel complex, 28 101 P2C25H22. Phosphine, methylenebis(di-phenyl-, palladium complex, 28 340 ruthenium complex, 26 276,28 225 P2C26H20, Phosphine, ethynnediylbis(di-phenyl-, ruthenium complex, 26 277, 28 226... 

The reaction of disubstituted acetylenes with 1,1,2,2-tetramethyldisilane catalyzed by bis(triethylphosphine)nickel(II) or palladium(II) dichloride provides a convenient source of siloles... 

Oxidative addition into the transition-metal center is an important reaction in organometallic chemistry. The Cl-C bond in dichlorophosphaethene is sensitive to this oxidative addition. Thus, the Mes -substituted 2,2-dihalophosphaethene 2 was allowed to react with tetrakis(triethylphosphine)platinum(0) to afford the corresponding complex 14 to result in the formation of diplatinum complex 15 [27] (Scheme 9). Bis(trimethylsilyl)amino-substituted dichlorophosphaethene 16 was treated with a nickel(O) reagent to afford the corresponding nickel(II) complex 17 [28] (Scheme 10). Complex 14 displays a carbenoid reaction as mentioned in Sect. 4. 

Transition-metal induced [1,2]-rearrangement is also available to obtain phosphaalkyne 39. Dichlorophosphaethene 2a was allowed to react with an equivalent amount of tetrakis(triphenylphosphine)palladium(0) to afford phosphaalkyne 39 through intermediates (Scheme 21) [37]. The rearrangement process takes place in the reaction of dibromophosphaethene 2b with a small amount (0.2 equiv.) of dibromobis(triphenylphosphine)nickel(II) in the presence of zinc and tetraethylammonium iodide through the generation of a nick-el(0) intermediate [38]. Complex 43 was isolated in the reaction of 2a and tetrakis(triethylphosphine)platinum(0) which could afford phosphaalkyne 39 [27,28,39]. 

The symmetrically-substituted 1,3-diyne 228a reacts with nickel(0)-benzyne complexes in the presence of an excess of triethylphosphine with regioselective formation of the 2,3-dialkynylnaphthalene 229 (Equation 12.56) [123]. The high... 

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