Photolytic preparation of (benzylideneacetone)carbonylphosphineiron(0) complexes. The molecular structures of Fe(CO)₂(PEt₃)(bda) and Fe(CO)₂(PPhMe₂)(bda) (bda benzylideneacetone)

The (benzylideneacetone) carbonylphosphine iron(0) complexes, Fe(CO)₂L(bda), Fe(CO)L′₂(bda) and Fe(CO)(dpe)(bda)(L = PEt₃, PPhMe₂, Me; L′ = PPhMe₂, PPh₂Me; dpe = [Ph₂P(CH₂)]₂) have been prepared by irradiating the corresponding tetracarbonylmonophosphine iron(0), tricarbonyldiphosphine iron(0) or tricabonyl-1,2-bis (diphenylphosphine)ethane iron(0) complexes in benzene in the presence of benzylideneacetone. The X-ray crystal structures of the complexes with L = PEt₃ (A) and PPhMe₂ (B) have been determined, and show that the Fe atom adopts a distorted octahedral coordinated geometry in which three of the sites are occupied by the bda ligand. The bond parameters in the bda ligand suggest that this coordinated group is intermediate between its ground and first excited states. The complex Fe(CO)₂(PEt₃(bda) crystallises in the monoclinic space group P2_l/c with a 10.203(3), b 12.964(4), c 16.960(6) Å, β 120.00(2)°, and Z = 4. The structure was solved by a combination of Patterson and Fourier diffence techniques and refined by blocked full matrix least squares to R = 0.035 for 3351 unique observed diffratometer data. The complex Fe(CO)₂(PPhMe₂)(bda) also crystallises in space group P2_l/c, with a 8.134(3), b 21.394(8), c 11.658(5) Å, β 108.18(2)° and Z = 4. The structure was solved and refined as above to R = 0.036 for 3498 diffractometer data. The IR and ¹H NMR data for all the complexes studied agree with the observed structures.