Formation of Imidates, Amides, Amines, Carbamates, and Ureas from the μ3-NPh Ligands of Fe3(μ-NPh)2(CO)9

Article abstract of DOI:10.1021/ja00247a018

The bis(nitrene) cluster Fe3(μ₃-NPh)2(CO)9 (1) reacts with Li, MeLi, PhLi, and NaOMe to form the formyl and acyl clusters 3-NPh)2(CO)8CR>^- (4, R=H; 6, R=Ph; 7, R=Me; 8, R=OMe).Formyl cluster 4 is unstable at room temperature and slowly loses CO to form the hydride cluster 3-NPh)2(CO)8>^-.The benzoyl cluster 7 reacts with EtOTf to yield the nitrene-carbene cluster Fe3(μ₃-NPh)2(CO)8(CPh) (9) which has been structurally characterized: Pbca, a=13.668(6) Angstroem, b=17.588(7) Angstroem, c=25.644(8) Angstroem, V=6164(7) Angstroem³, Z=8, R=0.060, R_w=0.075 for 2982 reflections with F_o>2?(F_o).The carbene ligand is bound to a basal iron atom, and the carbene carbon lies within the Fe3 plane.The carbene and nitrene ligands in 9 couple to form the imidate PhN=C(OEt)Ph when 9 is exposed to air or allowed to stand in solution for prolonged periods under CO or N2 atmospheres.A crossover experiment showed this coupling to be strictly intramolecular.Similar nitrene-benzoyl coupling from 7 gives benzanilide, and the methoxycarbonyl and nitrene ligands in 8 couple to give methyl N-phenylcarbamate when the clusters are oxidatively degraded with ⁺.The latter reaction models mechanictis suggestions previously made for the M3(CO)12 (M=Fe, Ru) catalyzed carbonylation of PhNO2 to yield carbamates.The bis(phosphinidene) cluster Fe3(μ-PPh)2(CO)9 (2) also reacts with PhLi to yield a benzoyl derivative, 3-PPh)2(CO)8(CPh)>^-.However, addition of EtOTf to this species does not result in a carbene cluster analogous to 9, but instead phosphinidene-carbene coupling occurs to give Fe3(μ₃-PPh)(μ₃-PhPCPh)(CO)9 which has been structurally characterized: P<*>, a=9.241(2) Angstroem, b=10.233(3) Angstroem, c=19.564(5) Angstroem, α=84.53(2) deg, β=84.43(2) deg, γ=76.41(2) deg, V=1784.7(8) Angstroem³, Z=2, R=0.0557, R_w=0.0602 for 3710 reflections with F_o>3?(F_o).The phosphorous atom of the μ₃-PhPCPh ligand bridges two iron atoms, and the ethoxy-substituted carbon is attached to the third iron atom.