The photolysis of Fe(CO) 3{P(OPh) 3} 2 and reaction of the photoproduct with alkynes: crystal structures of Fe(CO) 2{P(OPh) 3} 2(η 2-PhCCPh), Fe(CO) 2{P(OPh) 3} 2{η 1:η 1-C(O)C(Me)C[CH(OEt) 2]C(O)} and Fe 2(CO) 4{P(OPh) 3} 2(PhCCH) 2

Abstract

UV-irradiation of Fe(CO) 3{P(OPh) 3} 2 ( 1) afforded an orthometallated iron hydride HFe(CO) 2{P(OPh) 3}{(PhO) 2POC 6H 4} ( 2) which was reacted in situ with alkynes R 1CCR 2. Internal alkynes reacted to give either η 2-alkyne Fe(CO) 2{P(OPh) 3} 2(η 2-R 1CCR 2) [ 3a, R 1=R 2=Ph; 3b, R 1=Ph, R 2=CH(OEt) 2] or maleoyl Fe(CO) 2{P(OPh) 3} 2{η 1:η 1-C(O)C(R 1)C(R 2)C(O)} [ 4a, R 1=Ph, R 2=Me; 4b, R 1=R 2=Me; 4c, R 1=Me, R 2=CH(OEt) 2; 4d, R 1=Me, R 2=CH 2OH; 4e, R 1=R 2=CH 2OH] complexes. The terminal alkyne HCCPh reacted with 2 to give the ferrole derivative Fe 2(CO) 4{P(OPh) 3} 2(PhCCH) 2 ( 5). The crystal structures of 3a, 4c and 5 were determined. Complex 3a is trigonal bipyramidal about the iron atom with trans apical phosphite ligands and an equatorial arrangement of the CO groups and alkyne CC moiety. Complex 4c is octahedral with trans phosphite ligands and cis carbonyl groups. The alkyne ligand has undergone double carbonylation to generate a ferracyclopentenedione (maleoyl) ring that occupies the remaining two coordination sites at the metal centre. Complex 5 is formally a derivative of Fe 2(CO) 9 in which an Fe(CO) 2{P(OPh) 3} moiety is π-bonded to a ferracyclopentadiene ring arising from the tail-to-tail coupling of two HCCPh ligands.