Synthesis and thermal decomposition of ( h1-C 6H 5CH 2) ( h5-C 5H 5)Fe(CO) 2, ( h1-C 6H 5CH 2) ( h5-C 5H 5)M(CO) 3 (M = Mo and W), and their polymer-bound analogs

Abstract

( h 1-Benzyl) ( h 5-cyclopentadienyl)dicarbonyliron, I, ( h 1-benzyl) ( h 5-cyclopentadienyl)tricarbonylmolybdenum, II, and its tungsten analog, III, have been prepared, along with linear and crosslinked polystyrenes with I, II, and III as pendant moieties, by the reaction of the corresponding metal carbonyl anions with benzyl chloride. The thermal decomposition of I neat, in decane, or in benzene at 140° gave first order carboniron bond homolysis and h 5-cyclopentadienyldicarbonyl] dimer, XI, its monobenzylated analog (C 6H 5CH 2C 5H 4)(C 5H 5)Fe 2(CO) 4, XII, dibenzyl, and tar. The mole ratio of XI/XII varied between 8–12. Neat decomposition of polymers containing bound I was slow at 140° but in solution decomposition proceeded to give XI, and polymer-bound dimer XIV at 160° was detected. Similarly, thermal decomposition of II gave (C 5H 5) 2Mo 2(CO) 6, XV, and its benzylated analogs (C 6H 5CH 2C 5H 4) (C 5H 5)Mo 2(CO) 6, XVI, and (C 6H 5CH 2C 5H 4) 2Mo 2(CO) 6, XVII, while decomposition of III gave (C 5H 5) 2W 2(CO) 6,XVIII, (C 6H 5CH 2C 5H 4) (C 5H 5)W 2(CO) 6,XIX and (C 6H 5CH 2C 5H 4) 2W 2(CO) 6, XX. In these cases benzyl migration to Cp rings predominates even in solution. Solution decompositions also generated dibenzyl except in cumene where toluene was formed. For the decompositions of II and III the results suggest the migrating benzyl groups never become separated from the developing dimer and might “ride up” to attack the endo side of the Cp rings. Both linear and crosslinked polymers with pendant units of II and III composed very slowly neat in the solid phase, faster in solution, and in both modes dimers XV and XVIII formed in addition to polymer-bound benzylated analogs of XVI and XIX. Crosslinked polymers were prepared with dimers XI, XV, and XVIII dispersed throughout.