title: Synthesis and characterization of mononuclear, pseudotetrahedral cobalt(III) compounds.
abstract: The preparation and characterization of two mononuclear cobalt(III) tropocoronand complexes, [Co(TC-5,5)](BF4) and [Co(TC-6,6)](BPh4), are reported. The cobalt(III) centers exist in rare pseudotetrahedral conformations, with twist angles of 65° and 74° for the [Co(TC-5,5](+) and [Co(TC-6,6)](+) species, respectively. Structural and electrochemical characteristics are compared with those of newly synthesized [Ga(TC-5,5)](GaCl4) and [Ga(TC-6,6)](GaCl4) analogues. The spin state of the pseudotetrahedral [Co(TC-6,6)](BPh4) compound was determined to be S = 2, a change in spin state from the value of S = 1 that occurs in the square-planar and distorted square-planar complexes, [Co(TC-3,3)](X) (X = BPh4, BAr'4) and [Co(TC-4,4)](BPh4), respectively.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
authors.forename: Julia
authors.initials: J
authors.lastname: Kozhukh
authors.forename: Mikael A
authors.initials: MA
authors.lastname: Minier
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Lippard
mesh_terms: D060326:Chemistry Techniques, Synthetic; D003035:Cobalt / Q000737:chemistry*; D004563:Electrochemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D003035:Cobalt