Reactions of the sigma,pi-furyl complex [Fe-2(CO)(6)(mu-Fu)(mu-PFu(2))] (Fu = C4H3O) with phosphines: Carbonyl substitution, migratory carbonyl insertion and cyclometallation-induced furan elimination

• The reactivity of the sigma,pi-furyl complex [Fe-2(CO)(6)(mu-Fu)(mu-PFu(2))] (1) towards PPh3 and a range of bidentate phosphines has been studied and a number of different reaction products have been identified. With PPh3, carbonyl substitution affords [Fe-2(CO)(5)(PPh3)(mu-Fu)(mu-PFu(2))] (2) in which the new phosphine is coordinated to the iron center that is sigma-coordinated by the bridging furyl moiety. With small bite-angle diphosphines - bis(diphenylphosphino) methane (dppm) and 1,8-bis(diphenylphosphino) naphthalene (dppn) - carbonyl substitution and migratory carbonyl insertion result to give the furyl-acyl complexes with bridging, [Fe-2(CO)(4)(mu-dppm)(mu-O]CeFu)(mu-PFu(2))] (3), or chelating, [Fe-2(CO)(4)(kappa(2)-dppn)(mu-O]CeFu)(mu-PFu(2))] (4), diphosphines, respectively. With the more flexible diphosphines Ph2P(CH2)(n)PPh2 (n = 2, dppe, n = 3, dppp), the cyclometallated products [Fe-2(CO)(5){mu,kappa(2)-C6H4PPh(CH2)(n)PPh2}(mu-PFu(2))] (n = 2, 5; n = 3, 6) are isolated as a result of carbonyl substitution and furan elimination, and a similar complex [Fe-2(CO)(5){mu,kappa(2)-C6H4PPh(C6H4)PPh2}(mu-PFu(2))] (7) is generated from the more rigid diphosphine bis(diphenylphosphino) benzene (dppb). With bis(diphenylphosphino)-1,1-binaphthalene (1,1-BINAP) the novel tridentate phosphine complex [Fe-2(CO)(5){mu,kappa(3)-C6H4P(C20H12PPh2)C(6)H(4)PFu}] (8) results from the putative coupling of cyclometallated diphosphine and difurylphosphido ligands, following elimination of two equivalents of furan. The crystal structures of 2, 3, 5 and 8 have been determined and allow a detailed insight into the overall reaction profile. (C) 2013 Elsevier B.V. All rights reserved.

Subject headings

NATURVETENSKAP  -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)

Keyword

Diiron

Furyl

Migratory insertion

Cyclometallation

Carbon-phosphorus

bond formation

Publication and Content Type

art (subject category)

ref (subject category)