1.1.2- tris ethenes

Difluorobenzocyclopropene (21) reacts with Ni(0) complexes across the central 7l-bond to give bicyclobutanes 385, with concomitant loss of ligands from the metal. With tris(ethene)Ni, and in the presence of tetraethylene diamine, one ethylene unit is inserted and the complex 386 results. ... 

The formation of nickela- and palladabicyclobutanes from ge/w-difluorocyclo-propabenzene has been recorded (Section V.A.4). Such bicyclobutane formation is diverted to a bridged nickelabicyclodecatriene with tris(ethene)nickel(0) when TEEDA is used in place of TMEDA (equation 34)277. However, the behaviour of l278 and its disilyl... 

Scheme 7.5 Preparation of bis(l,5-cyclooctadiene)platinum(0) (19) and its reactions with ethene to tris(ethene)platinum(0) (20) and with tert-butylisocyanide to the trinuclear platinum cluster 21 (R = fBu)...

While the reaction of 9 with tris(ethene)nickel(0) in the presence of A,A,W,Af -tetramethyl-ethylenediamine leads to coordination of the cyclopropene double bond with formation of a metallacyclopropane derivative (see Section 1.), the presence of N,N,N, N -tet-... 

PtCgH,2, Platinum 0), tris ethene)-, 28 129 PtC,jH24, Platinum 0), bis l,5-cycloocta-diene)-, 28 126... 

Tris(ethene)platinum(0) is stable for several hours at 20°C under 1 atm of ethene and keeps for many weeks at — 20°C. In the absence of ethene, decomposition to metallic platinum occurs in minutes at room temperature. The complex is quite volatile, with a vile smeU, and sublimes slowly at 20°C in an atmosphere of ethene onto a cold finger at 0°C. 

Other Complexes. Several other classes of organonickel complexes are known. AHyl bromide and nickel carbonyl react to give a member of the TT-aHyl system [12012-90-7], [7T-C3H3NiBr]2 (100). Tris(r -ethene)nickel [50696-82-7] reacts with acetylene and l,2-bis(diisopropylphosphino)ethane to... 

A striking example of a macrocyclic closure is found in the double stitching done in the final step of the synthesis of the immunosuppressant rapamycin. Bis-1,2-(tri-n-butylstannyl)ethene reacted with the diiodide to close a 31-membered ring in 28% yield at 70% conversion. The intermediate iodostannane (from a single coupling) was also isolated in about 30% yield and could be cyclized in a second step.210... 

Vitamin B12 catalyzed also the dechlorination of tetrachloroethene (PCE) to tri-chloroethene (TCE) and 1,2-dichloroethene (DCE) in the presence of dithiothreitol or Ti(III) citrate [137-141], but zero-valent metals have also been used as bulk electron donors [142, 143]. With vitamin B12, carbon mass recoveries were 81-84% for PCE reduction and 89% for TCE reduction cis-l,2-DCE, ethene, and ethyne were the main products [138, 139]. Using Ni(II) humic acid complexes, TCE reduction was more rapid, leading to ethane and ethene as the primary products [144, 145]. Angst, Schwarzenbach and colleagues [140, 141] have shown that the corrinoid-catalyzed dechlorinations of the DCE isomers and vinyl chloride (VC) to ethene and ethyne were pH-dependent, and showed the reactivity order 1,1-DCE>VC> trans-DCE>cis-DCE. Similar results have been obtained by Lesage and colleagues [146]. Dror and Schlautmann [147, 148] have demonstrated the importance of specific core metals and their solubility for the reactivity of a porphyrin complex. 

Unlike petroleum hydrocarbons, organic compounds in general followed a different evolutionary path. Chlorinated solvents are a common group of organic compounds, and are also the most frequently encountered contaminant in groundwater. Common industrial chemicals that are characterized as chlorinated solvents include trichloro-ethene (TCE), 1,1,1-trichloroethane (TCA), tetrachloroethene (PCE) or perchloro-ethylene, chlorofluorocarbon (Freon)-113 (i.e., 1,1,2-trichloroethane or 1,2,2-tri-fluoroethane), and methylene chloride. In 1997, the EPA reported the presence of TCE and PCE in 852 of 945 groundwater supply systems throughout the United States and in 771 of 1420 Superfund sites. 

The water-soluble palladium complex prepared from [Pd(MeCN)4](Bp4)2 and tetrasulfonated DPPP (34, n=3, m=0) catalyzed the copolymerization of CO and ethene in neutral aqueous solutions with much lower activity [21 g copolymer (g Pd) h ] [53] than the organosoluble analogue in methanol. Addition of strong Brpnsted acids with weakly coordinating anions substantially accelerated the reaction, and with a catalyst obtained from the same ligand and from [Pd(OTs)2(MeCN)2] but in the presence of p-toluenesulfonic acid (TsOH) 4 kg copolymer was produced per g Pd in one hour [54-56] (Scheme 7.16). Other tetrasulfonated diphosphines (34, n=2, 4 or 5, m=0) were also tried in place of the DPPP derivative, but only the sulfonated DPPB (n=4) gave a catalyst with considerably higher activity [56], Albeit with lower productivity, these Pd-complexes also catalyze the CO/ethene/propene terpolymerization. 

Analog reagiert Brom-ethen mit 3,3-Dimethoxy-propen und Piperidin bei 100° (20 h) in Gegenwart von Palladium-acetat und Tris-[2-methyl-phenyl]-phosphan zu 5,5-Dimethoxy-1 -piperidim-2-penten (57%)2. 

A solution of tris(triphenylphosphanc)tetramethylenenickel(II) in toluene was treated with ethene (3.83 kPa), and cyclobutane and butenes were formed, The highest selectivity in favor of cyclobutane (72% in addition to 28% of butenes) was obtained with a 0.0023 M concentration of the catalyst in toluene at 0 A in 72 hours (turnover C4/Ni = 13). Substituted alkenes gave stable metallacycles. which could be converted to cyclobutane derivatives by oxidative decomposition.6... 

Thermal decomposition of l,l,l-tris(triphenylphosphanyl)nickelacyclopentane (9a) gave ethene (90%) and cyclobutane (10%), while thermal decomposition of l,l-bis(triphenylphos-phanyl)nickelacyclopentane (8b), under the same conditions, gave cyclobutanc ( 70%) in addition to ethene (5%) and but-l-ene (25%). Under related conditions, l,l-bis(tricyclo-hexylphosphanyl)nickelacyclopentane (8c) gave exclusively but-l-ene. However, under optimized conditions (see table below), cyclobutane (10) becomes the main product.126-127... 

Monomers are shown in Table 2.1 and in Figure 2.1. The most important monomer is norbornene. Norbornene is in made from di-cyclopentadiene (DCPD) and ethene by a Diels-Alder reaction. 5-Tri-ethoxysilyl-2-norbomene is used for crosslinkable compositions (2). 

Difluoroethene is partially reduced to vinyl fluoride and trifluoroethene to 1.2-difluoro-ethene by dimethyltin hydride.31 Long-chain 1.1-difluoroalk-l-enes are selectively reduced by complex hydrides to the corresponding monofluoroalkcnes in high yields.32 A series of fluo-rinated cthenes, from mono-, di-. tri- to tetrafluoroethene, are reduced by diborane in the gas phase to give a mixture of ethenc and lower-fluorinated ethenes.33... 

---