title: Metal-metal interactions in C3-symmetric diiron imido complexes linked by phosphinoamide ligands.
abstract: The tris(phosphinoamide)-bridged Fe(II)Fe(II) diiron complex Fe(μ-(i)PrNPPh2)3Fe(η(2)-(i)PrNPPh2) (1) can be reduced in the absence or presence of PMe3 to generate the mixed-valence Fe(II)Fe(I) complexes Fe(μ-(i)PrNPPh2)3Fe(PPh2NH(i)Pr) (2) or Fe(μ-(i)PrNPPh2)3Fe(PMe3) (3), respectively. Following a typical oxidative group transfer procedure, treatment of 2 or 3 with organic azides generates the mixed-valent Fe(II)Fe(III) imido complexes Fe((i)PrNPPh2)3Fe≡NR (R = (t)Bu (4), Ad (5), 2,4,6-trimethylphenyl (6)). These complexes represent the first examples of first-row bimetallic complexes featuring both metal-ligand multiple bonds and metal-metal bonds. The reduced complexes 2 and 3 and imido complexes 4-6 have been characterized via X-ray crystallography, Mössbauer spectroscopy, cyclic voltammetry, and SQUID magnetometry, and a theoretical description of the bonding within these diiron complexes has been obtained using computational methods. The effect of the metal-metal interaction on the electronic structure and bonding in diiron imido complexes 4-6 is discussed in the context of similar monometallic iron imido complexes.
authors.affiliation: Department of Chemistry, Brandeis University, 415 South Street MS 015, Waltham, Massachusetts 02454, United States.
authors.forename: Subramaniam
authors.initials: S
authors.lastname: Kuppuswamy
authors.forename: Tamara M
authors.initials: TM
authors.lastname: Powers
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Johnson
authors.forename: Mark W
authors.initials: MW
authors.lastname: Bezpalko
authors.forename: Carl K
authors.initials: CK
authors.lastname: Brozek
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Foxman
authors.forename: Louise A
authors.initials: LA
authors.lastname: Berben
authors.forename: Christine M
authors.initials: CM
authors.lastname: Thomas
mesh_terms: D000577:Amides / Q000737:chemistry*; D018360:Crystallography, X-Ray; D007094:Imides / Q000737:chemistry*; D058085:Iron Compounds / Q000737:chemistry*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010720:Phosphines / Q000737:chemistry*; D015204:Spectroscopy, Mossbauer
chemical_list: D000577:Amides; D007094:Imides; D058085:Iron Compounds; D010720:Phosphines