title: Synthesis and characterization of (smif)2M(n) (n = 0, M = V, Cr, Mn, Fe, Co, Ni, Ru; n = +1, M = Cr, Mn, Co, Rh, Ir; smif =1,3-di-(2-pyridyl)-2-azaallyl).
abstract: A series of Werner complexes featuring the tridentate ligand smif, that is, 1,3-di-(2-pyridyl)-2-azaallyl, have been prepared. Syntheses of (smif)(2)M (1-M; M = Cr, Fe) were accomplished via treatment of M(NSiMe(3))(2)(THF)(n) (M = Cr, n = 2; Fe, n = 1) with 2 equiv of (smif)H (1,3-di-(2-pyridyl)-2-azapropene); ortho-methylated ((o)Mesmif)(2)Fe (2-Fe) and ((o)Me(2)smif)(2)Fe (3-Fe) were similarly prepared. Metatheses of MX(2) variants with 2 equiv of Li(smif) or Na(smif) generated 1-M (M = Cr, Mn, Fe, Co, Ni, Zn, Ru). Metathesis of VCl(3)(THF)(3) with 2 Li(smif) with a reducing equiv of Na/Hg present afforded 1-V, while 2 Na(smif) and IrCl(3)(THF)(3) in the presence of NaBPh(4) gave [(smif)(2)Ir]BPh(4) (1(+)-Ir). Electrochemical experiments led to the oxidation of 1-M (M = Cr, Mn, Co) by AgOTf to produce [(smif)(2)M]OTf (1(+)-M), and treatment of Rh(2)(O(2)CCF(3))(4) with 4 equiv Na(smif) and 2 AgOTf gave 1(+)-Rh. Characterizations by NMR, EPR, and UV-vis spectroscopies, SQUID magnetometry, X-ray crystallography, and DFT calculations are presented. Intraligand (IL) transitions derived from promotion of electrons from the unique CNC(nb) (nonbonding) orbitals of the smif backbone to ligand π*-type orbitals are intense (ε ≈ 10,000-60,000 M(-1)cm(-1)), dominate the UV-visible spectra, and give crystals a metallic-looking appearance. High energy K-edge spectroscopy was used to show that the smif in 1-Cr is redox noninnocent, and its electron configuration is best described as (smif(-))(smif(2-))Cr(III); an unusual S = 1 EPR spectrum (X-band) was obtained for 1-Cr.
authors.affiliation: Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Brenda A
authors.initials: BA
authors.lastname: Frazier
authors.forename: Erika R
authors.initials: ER
authors.lastname: Bartholomew
authors.forename: Peter T
authors.initials: PT
authors.lastname: Wolczanski
authors.forename: Serena
authors.initials: S
authors.lastname: DeBeer
authors.forename: Mitk'El
authors.initials: M
authors.lastname: Santiago-Berrios
authors.forename: Hector D
authors.initials: HD
authors.lastname: Abruña
authors.forename: Emil B
authors.initials: EB
authors.lastname: Lobkovsky
authors.forename: Suzanne C
authors.initials: SC
authors.lastname: Bart
authors.forename: Susanne
authors.initials: S
authors.lastname: Mossin
authors.forename: Karsten
authors.initials: K
authors.lastname: Meyer
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Cundari
mesh_terms: D056831:Coordination Complexes / Q000138:chemical synthesis*; D018360:Crystallography, X-Ray; D004563:Electrochemistry; D004583:Electrons; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D060306:Magnetometry; D008670:Metals / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011725:Pyridines / Q000138:chemical synthesis*; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared
chemical_list: D056831:Coordination Complexes; D008024:Ligands; D008670:Metals; D011725:Pyridines