Trichloride analogue

A variety of Group 4 metal complexes, in combination with common olefin polymerization activators, have been evaluated as potential catalysts for syn-diospecific polymerization of styrene (for reviews, see Refs. 114, 115, 123, and 426). Monocyclopentadienyl and monoindenyl titanocenes generally exhibit the highest activities (eq. 5) (112-127). Curiously, half-sandwich titanium-trifluoride-based catalysts are more active than their trichloride analogues (124,427,428). The polymerization mechanism for sPS formation is under debate. Kinetic studies and spectroscopic investigations of the catalytic systems suggest a cationic Ti(III) complex as the active species (123). 

Arsenin and Its Derivatives. Arsenin (arsabenzene) [289-31-6], C H As, the arsenic analogue of pyridine, can be prepared by the treatment of l,4-dihydro-l,l-dibutylstaimabenzene with arsenic trichloride (118) ... 

Boron trifluoride, sulphur and disulphur dichlorides, phosphorus trichloride in the liquid state cause potassium to combust. The same is true for phosphorus pentachloride in the solid state. In the latter case the same accident happened with gaseous halide. The same is also true for the bromide analogues of these compounds. 

Heterocyclic phosphines 32 were prepared from base-induced condensation of a secondary 1,8-diamino-naphthalene with phosphorus trichloride (the corresponding As- and Sb-analogues were obtained analogously) and converted into cyclic phosphenium cations 33 by Lewis acid promoted halide abstraction using GaCl3 or trimethylsilyl triflate as reagents (Scheme 18) [15, 92],... 

The reaction of the stannane (176) with phosphorus trichloride gives the phosphorin (177). The electron-donating methyl group reinforces the ring dipole, the negative end of which is the phosphorus atom.189 The dibenzo analogue (178) has also been prepared and its electronic structure studied by photoelectron spectroscopy.160... 

Coordinated cyanide in [Fe(phen)(CN)4], prepared by chlorine oxidation of K2 Fe(phen)(CN)4], can act as a bridging ligand, for example in the complexes [ Fe(phen)(CN)4 2M-(H20)2] 4H20, where M = Mn or Zn, whose structure is of double zigzag chains, and of bipy analogues. There is similar bridging to ytterbium, as in (phen)2Fe //-CN— YbCl3(H20)— NC 2Fe(phen)2, obtained from the reaction of ytterbium trichloride with [Fe(phen)2(CN)2]. ... 

The direct synthesis of the fused ring compound (55) from the reaction of phosphorus trichloride with ethylamine hydrochloride has already been described (Scheme 16). Its N-methyl analogue (67) can be obtained from the reaction of (MeNPX)3 (X = Cl or Br) with heptamethyldisilazane (Scheme 19). The identification of the structures of these fused-ring compounds, which are structurally related to the bicyclo(3.3.1)nonane carbocycles, pose difficult problems. An example of their... 

The reaction of sulfur dichloride with benzonitrile in the presence of a Lewis acid catalyst yields 3,5-diphenyl-l,2,4-thiadiazole (39), along with the 3-o-chlorophenyl (278) and 3-p-chlorophenyl (279) analogues in a total yield of 80%. The proposed mechanism proceeds via a complex between benzonitrile, Lewis acid for example, aluminum trichloride, and sulfur dichloride to give an intermediate (280) which then adds a second molecule of nitrile (Scheme 62) <83BCJ180>. 

The most intriguing difference between the chemical properties of cyclopolysilanes and those of cycloalkanes is the ability of the former to form either anion or cation radicals upon one-electron reduction or oxidation, respectively. For example, the cyclic pentamer (Mc2Si)5 is reduced to the corresponding radical anion by sodium-potassium alloy in diethyl ether [see eqn (4.1) in Section 4.1.3], whereas the hexamer (Me2Si)6 is oxidised by aluminium trichloride in dichlor-omethane to the corresponding cation radical. In both cases the EPR spectra of the radical ions can be interpreted in terms of a-electron delocalisation over the entire polysilane ring (see Section 10.1.4.1). In this respect, the cyclosilanes resemble aromatic hydrocarbons rather than their aliphatic analogues. 

Organocerium derivatives posses low basicity. 5-Pyrimidylcerium dichlorides (e.g. 881) are available by low-temperature metal-metal exchange using cerium trichloride and 5-lithiated pyrimidines (e.g. 880, R = SMe, R = H). The 5-pyrimidinylcerium dichloride was superior to its 5-lithio analogue in reactions with aldehydes and ketones, especially in reactions with enolizable aldehydes and ketones (89ACS816). 

Agrofoglio has reported the syntheses of carbocyclic analogues of phos-phononucleosides (28a-e). Compound (28a) was synthesised by introducing the heterocycle under Mitsunobu conditions, while compounds (28b-e) were obtained by building up the base around a cyclopentylamine moiety0-Alkyl-ff-phosphonates of AZT (29a-e) and D4T (30a-e) have been prepared via a simple one-pot route under mild conditions and in reasonable isolated yields using phosphorus trichloride, followed by alcoholysis and dealkylation by triethylamine. ... 

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