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Migratory insertion and CO substitution reactions of the beta,gamma-unsaturated esters and amides [Fe-2(CO)(5)(mu-PPh2)(mu-eta(1):eta(2)-{NuC(O)CH2}C=CH2}] (Nu = OMe, OEt, OPri,NHPh, NHBut): synthesis and characterisation of acyl-bridged [Fe-2(CO)(4)L-2(mu-PPh2)(mu-C=O{C=CH2}CH2C(O)Nu)](L-2 = dppm, dppe) and alkenyl-bridged [Fe-2(CO)(4){P(Ome)(3)}(2)(mu-eta(1):eta(2)-{NuC(O)CH2}C=CH2)]

Lookup NU author(s): Dr Simon DohertyORCiD, Mark Waugh, Thomas Scanlan, Dr Mark Elsegood, Professor William Clegg

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Abstract

Reaction of the beta,gamma -unsaturated esters and amides [Fe-2(CO)(5)(mu -PPh2)(mu-eta (1)(O):eta (1)(C):eta (2)(C)-{NuC(O)CH2}C=CH2)] (Nu = OMe, la; R = Oft, Ib; R = OPri, Ic, R = NHPh, Id, R = NHBut, le) with dppe and dppm results in displacement of the acyl carbonyl and migratory insertion to give the alpha,beta -unsaturated acyl derivatives [Fe-2(CO)(4)(eta (2)-dppe)(mu -PPh2)(mu -C=O{C=CH2}CH2C(O)Nu)] (Nu = OMe, 2a; R = OEt, 2b; R = OPri, 2c, R = NHPh, 2d, R = NHBut, 2e) and [Fe-2(CO)(4)(mu -dppm)(mu -PPh2)(mu -C=O{C=CH2}CH2C(O)Nu)] (R = OMe, 3a; R = Oft, 3b; R = OPri, 3c, R = NHPh, 3d), respectively. Single-crystal X-ray analyses of 2a and 3a has revealed that the dppe ligand in the former chelates, with one arm binding trans and one cis to the phosphido bridge, while the dppm and phosphido group in the latter both bridge the iron-iron bond and are ti ans to one another. In contrast, reaction of la-e with trimethylphosphite results in displacement of the ester carbonyl oxygen to give [Fe-2(CO)(5){P(OMe)(3)}(mu -PPh2)(mu-eta (1)(C):eta (2)(C)-{NuC(O)CH2}C=CH2)] (Nu = OMe, 4a; R = OEt, 4b; R = OPri, 4c) followed by CO substitution to give [Fe-2(CO)(4){P(OMe)(3)}(2)(mu -PPh2)(mu-eta (1)(C):eta (2)(C)-{Nu(O)CCH2}C=CH2)] (Nu = OMe, 6a; R = OEt, 6b; R = OPri, 6c) with no evidence for the formation of the corresponding acyl-bridged derivative. Thermolysis of toluene solutions of 4a-c result in loss of CO and coordination of the oxygen atom of the ester carbonyl to give [Fe-2(CO)(4){P(OMe)(3)}(mu -PPh2)(mu-eta (1)(O):eta (1)(C):eta (2)(C)-{NuC(O)CH2}C=CH2)] (Nu = OMe, 5a; R = OEt, 5b; R = OPri, 5c), an intermediate in the formation of 6a-c. Complexes 5a and 6a have been characterised by single-crystal X-ray crystallography. (C) 2001 Elsevier Science B.V. All rights reserved.

Publication metadata

Author(s): Doherty S, Hogarth G, Waugh M, Scanlan TH, Elsegood MRJ, Clegg W

Publication type: Article

Publication status: Published

Journal: Journal of Organometallic Chemistry

Year: 2001

Volume: 620

Issue: 1-2

Pages: 150-164

ISSN (print): 0022-328X

ISSN (electronic): 1872-8561

Publisher: Elsevier S.A.

URL: http://dx.doi.org/10.1016/S0022-328X(00)00823-8

DOI: 10.1016/S0022-328X(00)00823-8

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