1,1-DICYCLOPENTADIENYL-3,3-DIMETHYLVANADA(IV)CYCLOBUTANE

Article abstract of DOI:10.1016/0022-328X(84)85052-4

The reaction of 1,3-bis(bromomagnesio)-2,2-dimethylpropane (1b) with dichlorodicyclopentadienylvanadium(IV) (5) gave 1,1-dicyclopentadienyl-3,3-dimethylvanada(IV)cyclobutane (4) in 30percent yield, contaminated with dicyclopentadienylneopentylvanadium(III) (12).Attempts to purify 4 were only partially successful due to its limited stability (t_1/2 = 4 h at 25 deg C in cyclopentane).Identification of 4 is therefore based on its having sufficient thermal stability for isolation, on its reaction with bromine to give 1,3-dibromo-2,2-dimethylpropane (2b), and especially on its ESR and 1H NMR spectra.The reaction of 4 with cyclohexanone (15) gave 17 and 18 as the main products; 17 is the aldol dimer of 15, while 18 may be derived from either 4 or 12.Because methylenecyclohexane (16) is not one of the reaction products, it is concluded that 4 does not have a pronounced tendency to fragment to give a metallacarbene (20).