THE FIRST WELL CHARACTERIZED FE(PHEN)CL-3 COMPLEX - STRUCTURE OF AQUOMONO(1,10-PHENANTHROLINE)IRON(III) TRICHLORIDE - [FE(PHEN)CL-3(H2O)]

The crystal structure of the neutral, pseudo-octahedral mono phenanthr oline iron(III) complex Fe(phen)Cl3H2O is reported, which surprisingly is the first well-characterized Fe(phen)Cl-3 complex (space group <P( 1)over bar>; a = 10.224(4) Angstrom, b = 10.603(3) Angstrom; c = 6.628 (2) Angstrom; alpha = 100.70(2)degrees, beta = 108.17(2)degrees, gamma = 92.06(2)degrees; R = R-w = 0.033). Of the three unidentate chloride ions, two are coplanar with phenanthroline ligand while the third is out of plane and is trans to the water molecule. The metal environment is distorted from regular octahedral due to the non-equivalent ligand donor set. The N-Fe-N bite angle of 75.6 degrees is compressed below right-angular with a corresponding opening of the other bond angles ar ound the iron in this plane. The Fe-Cl bonds are inequivalent, ranging from 2.25 to 2.35 Angstrom the axial Fe-Cl bond being elongated. The axial aquo group is tilted towards the phenanthroline ring, making an angle of 83.8 degrees with N(1) and 81.8 degrees with N(2), respective ly Comparison with the Mn(III) analog Yields the effect of changing fr om a high spin d(5) to a high spin d(4) center. (C) 1997 Elsevier Scie nce Ltd.