Synthesis and structures of chromium tricarbonyl complexes of benzylic halides and benzylic alcohols

Chromium tricarbonyl complexes of mono-, bis- and tris-(hydroxymethyl) subs tituted benzene have been prepared via direct thermolysis of the alcohol an d chromium hexacarbonyl in dibutyl ether-THF. Conversion into the correspon ding benzyl halide complexes has been carried out using either PBr3, HBr (a q), HBr in glacial acetic acid or BX3 (X=Cl, Br or I). A comparative study showed that PBr3 and BBr3 give similar yields and purity and are superior t o HBr. Crystallographic studies have been carried out on three benzyl alcoh ol complexes [Cr{eta(6)-C6H4(CH2OH)(2)-1,4}(CO)(3)], [Cr{eta(6)-C6Me4(CH2OH )(2)-1,4}(CO)(3)] and [Cr{eta(6)-C6H3(CH2OH)(3)-1,3,5}(CO)(3)] and on two b enzyl bromide complexes [Cr(eta(6)-C6H5CH2Br)(CO)(3)] and [Cr{eta(6)-C6H4(C H2Br)(2)-1,4}(CO)(3)].