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Reactivity of bis(diphenylphosphino) methane at a di-iron centre: Thermally induced rearrangements of dimetallacyclopentenone complexes [Fe-2(CO)(5){mu-sigma:eta(3)-C(O)CRCR}(mu-dppm)]

Hogarth, G; Knox, SAR; Lloyd, BR; Macpherson, KA; Morton, DAV; Orpen, AG; (1996) Reactivity of bis(diphenylphosphino) methane at a di-iron centre: Thermally induced rearrangements of dimetallacyclopentenone complexes [Fe-2(CO)(5){mu-sigma:eta(3)-C(O)CRCR}(mu-dppm)]. INORG CHIM ACTA , 251 (1-2) 167 - 176.

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Abstract

In toluene at 100 degrees C the dimetallacyclopentenone complex [Fe-2(CO)(5){mu-sigma:eta(3)-C(O)CHCH}(mu-dppm)] (1a) isomerises to the mu-vinyl complex [Fe-2(CO)(6){mu-C(CH2)P(Ph(2))CH(2)PPh}] (2) via intramolecular nucleophilic attack of phosphorus on a carbon of the metallacycle, with an associated 1,2-hydrogen shift and C-C bond cleavage. On further heating to 110 degrees C, 2 in turn is transformed to isomeric [Fe-2(CO)(6)-{mu-C(CH(2)Ph)P(Ph(2))CH(2)PPh}] (3), arising from transfer of a phenyl group from phosphorus to carbon, and the complex [Fe-2(CO)(5)-{mu-Ph(2)PCH(2)P(Ph)C6H4C(CH3)}] (4a), resulting from more complex rearrangement. Heating the complexes [Fe-2(CO)(5)-{mu-sigma:eta(3)-C(O)CRCH}(mu-dppm)] (R=Me (1b), Ph (1c)) gave only [Fe-2(CO)(5){mu-Ph(2)PCH(2)P(Ph)C6H4C(CH(2)R)}] (4b, 4c), thelikely intermediates analogous to 2 and 3 not being detectable. The structures of 2, 3 and 4c were established by X-ray diffraction, providing an insight into the molecular manoeuvres involved in the rearrangements. In contrast to the ready thermolysis of la-c, in which the diphosphine and organic moieties lie cis to one another, the analogous trans complexes [Fe-2(CO)(5){mu-sigma:eta(3)-C(O)CRCR} (mu-dppm)] (R=Me (1d), Ph (1e)) are stable in refluxing toluene, partly attributable to the inability of phosphorus to attack the distant metallacycle.

Type:Article
Title:Reactivity of bis(diphenylphosphino) methane at a di-iron centre: Thermally induced rearrangements of dimetallacyclopentenone complexes [Fe-2(CO)(5){mu-sigma:eta(3)-C(O)CRCR}(mu-dppm)]
Keywords:crystal structures, iron complexes, diphosphinomethane complexes, dimetallacycle complexes, dinuclear complexes, CRYSTAL-STRUCTURES, CENTERS
UCL classification:UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Chemistry

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