Group II halides

Other Group II halides are essentially ionic and therefore have relatively high m.p., the melts acting as conductors, and they are soluble in water but not in organic solvents. 

The lower members in Group II form essentially ionic halides, with magnesium having intermediate properties, and both magnesium bromide and iodide dissolve in organic solvents. 

Grignard reagents are prepared from organic halides by reaction with magnesium a Group II metal... 

The yield increased with increasing the ratio of alumina-supported copper(II) bromide to alkoxybenzenes. The size of alkoxy group did not influence significantly the yield and the ratio of p/o. Nonpolar solvents such as benzene and hexane were better than polar solvent. Polar solvents such as chloroform and tetrahydrofiiran decreased the yield. It is suggested that these polar solvents may be strongly adsorbed on the surface of the reagent. The reaction did not proceed in ethanol to be due to the elution of copper(II) bromide from the alumina to the solution. It is known that the reaction of aromatic hydrocarbons with copper(II) halides in nonpolar solvents proceeds between aromatic hydrocarbons and solid copper(II) halides and not between hydrocarbons and dissolved copper(II) halides (ref. 6). 

These ligands all form 1 1 complexes with platinum(II) halides which are non-conductors, monomeric and, in the solid state, contain one coordinated and two free double bonds. Proton n.m.r. data indicate that all three double bonds are equivalent in solution due to a rapid equilibrium between bonded and non-bonded —CH=CH2 groups. The phosphine and arsine complexes PtBraL (L = tvpp, tvpa) react with two equivalents of bromine giving what are believed to be platinum(II) species containing one coordinated double bond and two —CHBr-CHaBr groups arising from the saturation by bromine of the two free double bonds. 

The sulphide ligands containing one butenyl group form chelate complexes with platinum(II) and palladium(II) halides. The chelated butyl pentenyl sulphide complexes could only be obtained for platinum-(II). The compounds containing two group VI atoms functioned as bidentate ligands by donation from the two sulphim atoms only. All these chelated olefinic sulphide complexes react with simple monodentate... 

In the presence of proton and/or Lewis acid and strong nucleophiles bicyclo[3.2.0]heptan-6-ones are converted to 3-substituted cycloheptanones (Table 15). Bicyclo[3.2.0]heptan-6-ones rearrange to give 3-iodocycloheptanones on treatment with iodotrimethylsilane. Zinc(II) iodide or mercury(II) halides as catalysts enhance the rate and the selectivity of the reaction.31 If a second, enolizable carbonyl group is present, an intramolecular alkylation may follow the ring enlargement under these reaction conditions.32 Consecutive treatment with tributyltin hydride/ 2,2 -azobisisobutyronitrile affords reduced, iodo-free cycloheptanones, whilst treatment with l,8-diazabicyclo[5.4.0]undecene yields cycloheptenones.33 Similarly, benzenethiol adds to the central bond of bicyclo[3.2.0]heptan-6-ones in the presence of zinc(II) chloride and hydrochloric acid under anhydrous conditions to form 3-(phenylsulfanyl)cycloheptanones.34... 

Although many complexes are known in which the trichlorostannate(II) anion functions as a donor to transition metals, very few to main group Lewis acids have been described and no strucural data are available. However, the complexes B- SnX2- -BF3 (X = Cl, Br, I B = NMe3, bipy, TMEDA and DMSO), in which the tin(II) halide functions simultaneously as both a Lewis acid and a Lewis base, have been reported.1 ... 

Metal cluster compounds can be conveniently grouped into two classes (I) polynuclear carbonyls, nitrosyls. and related compounds and (II) halide and oxide complexes. The former group was included m Chapter 15. The second class will be discussed in this section.146... 

For the less electropositive metals, direct reaction between the bulk metal and alcohols does not readily occur. However, for the Group II, III and lanthanide metals, reaction will occur in the presence of a catalyst.12,15 Typical catalysts are iodine or a mercury(II) halide and their action is believed to be either in cleaning the metal surface or in forming intermediate halide derivatives which then undergo facile reaction with the alcohol (equation 2).12... 

Olefinic compounds will often insert into carbon-transition metal bonds as CO does, and this reaction is an important step in many catalytic syntheses. When this step is combined with an oxidative addition of an organic halide to a palladium(O) complex in the presence of a base, a very useful, catalytic olefinic substitution reaction results (26-29). The oxidative addition produces an organopalladium(II) halide, which then adds 1,2 to the olefinic reactant (insertion reaction). The adduct is unstable if there are hydrogens beta to the palladium group and elimination of a hydridopalladium salt occurs, forming a substituted olefinic product. The hydridopalladium salt then reforms the... 

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