227205-40-5Relevant academic research and scientific papers
1,2-diphosphetene, 1,2-diphosphete, and 1,3-diphosphete metal complexes: novel access by ring contraction, cyelodimerization, and intramolecular redox reactions
Heinemann, Frank W.,Kummer, Susanne,Seiss-Brandl, Udo,Zenneck, Ulrich
, p. 2021 - 2029 (2008/10/08)
The reaction of [Cr(CO)5(THF)] and pentaphenyl-1,2,3-triphospholene affords a single stereoisomer of [(pentaphenyl-1,3-η-1,2,3-triphospholene)(Cr(CO)5)2] (6). Visible light photolysis of 6 causes a ring contraction and [(trans-tetraphenyl-1,2-η-1,2-diphosphetene)(Cr-(CO)5) 2] (7a) is formed, whose stereochemistry was elucidated by X-ray crystallography. trans-1,2-Dichloro-3,4-di-terf-butyl-1,2-diphosphetene (2a) and [Fe2(CO)9] form the σ complexes [(trans-1,2-dichloro-3,4-di-tert-butyl-1-η-1,2-diphosphetene)Fe(CO) 4] (8a) and [(trans-1,2-dichloro-3,4-di-tert-butyl-1,2-η-1,2-diphosphetene)(Fe(CO) 4)2] (8b), depending on the relative concentration of the starting materials. 8a has been proven to be an intermediate in the formation of 8b. Heating of neat 8b in a vacuum leads to the elimination of the chlorine substituents in an intramolecular redox reaction and [(3,4-di-tert-butyl-η4-1,2-diphosphete)-Fe(CO)3] (9a) is formed. This is the first specific reaction, leading to a 1,2-diphosphete complex. 9a and its 1,3-isomer 10a react with [Cr(CO)5(THF)] to form the mono- and diaddition products [1-η-{(3,4-di-tert-butyl-η4-1,2-diphosphete)Fe(CO) 3}Cr(CO)5] (9b), [1,2-η-{(3,4-di-feru-butyl-η4-1,2-diphosphete)Fe(CO) 3}(Cr(CO)5)2](9c))[1-η-{(2,4-di-tert-butyl-η 4-1,3-diphosphete)Fe(CO)3}Cr(CO)5] (10b), and [1,3-η-{(2,4-di-tert-butyl-η4-1,3-diphosphete)-Fe(CO) 3}(Cr(CO)5)2] (10c), respectively. X-ray crystallographic studies for 9c and 10c give some insight into the bonding situation of the compounds, σ- and π-complexing properties of the diphosphete ligands are almost independent of each other and significant back-bonding from the iron atom to the ligand π* orbitals occurs in both cases.
