Photochemical synthesis, structure and reactivity of (eta(6)-arene)chromium-hydrido stannyl and -bis-stannyl complexes.

摘要

Synthesis and studies of the structure and reactivity of ({dollar}etasp6{dollar}-arene)-chromium complexes bearing stannyl ligands have been achieved. Photolysis of ({dollar}etasp6{dollar}-arene)Cr(CO){dollar}sb3{dollar} complexes and H-SnPh{dollar}sb3{dollar} in the appropriate solvent at room temperature has led to two classes of compounds: hydrido stannyl compounds containing an {dollar}etasp2{dollar}-H-SnPh{dollar}sb3{dollar} ligand and bis-stannyl compounds containing two SnPh{dollar}sb3{dollar} ligands. Complexes of different arenes have been obtained and characterized including X-ray structures of some of them. {dollar}sp1{dollar}H NMR data as well as X-ray structural data provide evidence for the existence of three-center two-electron bond in the hydrido stannyl complexes. The bis-stannyl complexes are shown by X-ray crystallography to contain two trans SnPh{dollar}sb3{dollar} and two trans CO ligands that, along with the arene ligand, adopt a piano-stool arrangement around the chromium center.; The reactivity of these complexes toward pyridine and triethylphosphine as well as their reactions toward CO have been studied. Arene exchange reactions between the bis-stannyl compounds and free arenes have been also studied. From these different reactions it was indicated that besides electronic effects, steric hinderence from the bulky stannyl ligands and the substituents on the arene ring plays an important role in determining the reactivity and stability of these compounds. Finally, attempts to prepare analogous complexes bearing germanium ligands are discussed.