PENTACOORDINATE FE(CO)3 COMPLEXES OF DIPHOSPHINE LIGANDS WITH BITE ANGLES GREATER THAN 120-DEGREES

The reaction of (benzylideneacetone)tricarbonyliron and trans-1,2-bis((diphenylphosphino)methyl)cyclopropane (1) in toluene produced [trans-1,2-bis((diphenylphosphino)methyl)cyclopropane]tricarbonyliron (3) in 24% yield. Crystals of 3 are orthorhombic with space group Pcba, a = 16.359 (5) Å, b = 16.711 (5) Å, c = 21.057 (6) Å, V = 5757 (3) Å3, and Z = 8. The X-ray crystal structure of 3 reveals a trigonal-bipyramidal geometry about the iron atom with diequatorial chelation by diphosphine 1 (P–Fe–P = 123.9 (1)°). The reaction of (benzylideneacetone)tricarbonyliron with 2,2′-bis((diphenylphosphino)methyl)-1,1′-biphenyl (2) formed [2,2′-bis((diphenylphosphino)methyl)-1,1′-biphenyl]tricarbonyliron (5) in 7% yield. Crystals of 5•CH2Cl2 are monoclinic with space group P21/n, a = 12.863 (3) Å, b = 15.173 (3) Å, c = 18.753 (4) Å, β = 95.51 (3)°, V= 3643.1 (13) Å3, and Z = 4. The X-ray structure of 5 exhibits a distorted-square-pyramidal geometry with an apical carbonyl ligand. The P-Fe-P angle is 152.0 (1)°; the basal carbonyls form a OC–Fe–CO angle of 141.8 (4)°. © 1990, American Chemical Society. All rights reserved.