Trigonal bipyramidal geometry and tridentate coordination mode of the tripod in FeCl(2) complexes with tris(2-pyridylmethyl)amine derivatives bis-alpha-substituted with bulky groups. structures and spectroscopic comparative studies.
A series of dichloroferrous complexes with ligands derived from the tris(2-pyridylmethyl)amine tripod has been prepared and characterized. The X-ray crystal structures of the complexes [bis(2-bromo-6-pyridylmethyl)(2-pyridylmethyl)amine]Fe(II)Cl(2) ((Br(2)TPA)Fe(II)Cl(2)) and [bis(2-phenyl-6-pyridylmethyl)(2-pyridylmethyl)amine]Fe(II)Cl(2), ((Ph(2)TPA)Fe(II)Cl(2)) are reported. In these complexes, the tripod coordinates in the tridentate mode, with a substituted pyridyl arm dangling away from the metal. Both complexes have a trigonal bipyramidal iron center with two equatorial chloride ions. Their crystal structures are compared with those of the [tris(2-pyridylmethyl)amine]Fe(II)Cl(2) and [(2-bromo-6-pyridylmethyl)bis(2-pyridylmethyl)amine]Fe(II)Cl(2) complexes ((TPA)Fe(II)Cl(2) and (BrTPA)Fe(II)Cl(2), respectively) in which the ligand coordinates in the tetradentate mode. For all complexes, the metal to ligand distances are systematically above the value of 2.0 A, and (1)H NMR displays paramagnetically shifted resonances with short relaxation times. This indicates that the iron is in a high-spin state. Electric conductivity measurements show that, for all complexes, the measured values lie within the same range, significantly below those expected for ionic complexes. Together with the analysis of the UV-visible and NMR data, this strongly suggests that the coordination mode of the tripod is retained in solution.
Mandon
Dominique
D
Laboratoire de Chimie Organométallique et de Catalyse and Laboratoire DECMET, UMR CNRS No. 7513, Université Louis Pasteur, Institut Le Bel, 4 rue Blaise Pascal, F-67070 Strasbourg Cedex, France. mandon@chimie.u-strasbg.fr
Machkour
Ahmed
A
Goetz
Sandrine
S
Welter
Richard
R
D002712:Chlorides; D018360:Crystallography, X-Ray; D004553:Electric Conductivity; D005290:Ferric Compounds / Q000737:chemistry*; D006860:Hydrogen Bonding; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008670:Metals / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D011725:Pyridines / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
D002712:Chlorides; D005290:Ferric Compounds; D008024:Ligands; D008670:Metals; D011725:Pyridines; C431843:tris(2-pyridylmethyl)amine; C024555:ferric chloride