Reactions of Fe-III with LiAlH4 and LiBH4 in the presence of bis(diphenylphosphino)methane (dppm) and CO. The crystal and molecular structures of trans-[Fe(Cl)(CO)(eta(2)-dppm)(2)] [FeCl4], trans-Fe(H)(2)(eta(2)-dppm)(2) and cis-[Fe(eta(2)-S2CH)(eta(2)-dppm)(2)]BF4

Reactions between Fe-III, dppm, CO as appropriate and LiAlH4 produce the Fe-II complexes trans-[Fe(Cl)(CO)(eta(2)-dppm)(2)][FeCl4]. (1a) trans-[Fe(H)(2)(eta(2)-dppm)(2)] (2) and trans-[Fe(H)(Cl)(eta(2)-dppm)(2)] (3), depending upon the reaction conditions. The trans octahedral structures, with chelating dppm ligands, of Ia and 2 have been established by X-ray crystallography. Compound 2 reacts with CO to produce the Fe-0 complex Fe(CO)(3)(eta(1)-dppm)(2) (4), identified by NMR spectrometry, and with H-2/HBF4 . Et2O to give the dihydrogen complex trans-[Fe(H)(eta(2)-H-2)(eta(2)-dppm)(2)]BF4 (5). The dihydrogen can be replaced with, for example, CO and CH3CN to give trans-[Fe(H)(L)(eta(2)-dppm)(2)]BF4 (L = CO, 6, and L = CH3CN, 7, respectively). With CS2, insertion into the Fe-bond of 5 occurs to produce the dithioformato complex cis-[Fe(eta(2)-S2CH)(eta(2)-dppm)(2)]BF4 (8), the structure of which is also reported. (C) 1997 Elsevier Science Ltd.