title: Paramagnetic Resonance of Cobalt(II) Trispyrazolylmethanes and Counterion Association.
abstract: Paramagnetic resonance studies (EPR, ESEEM, ENDOR, and NMR) of a series of cobalt(II) bis-trispyrazolylmethane tetrafluoroborates are presented. The complexes studied include the parent, unsubstituted ligand (Tpm), two pyrazole-substituted derivatives (4Me and 3,5-diMe), and tris(1-pyrazolyl)ethane (Tpe), which includes a methyl group on the apical carbon atom. NMR and ENDOR establish the magnitude of1H hyperfine couplings, while ESEEM provides information on the coordinated14N. The data show that the pyrazole 3-position is more electron rich in the Tpm analogues, that the geometry about the apical atom influences the magnetic resonance, and that apical atom geometry appears more fixed in Tpm than in Tp. NMR and ENDOR establish that the BF4-counterion remains associated in fluid solution. In the case of the Tpm3,5Mecomplex, it appears to associate in solution, in the same position it occupies in the X-ray structure.
authors.affiliation: Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States.
authors.forename: Amy R
authors.initials: AR
authors.lastname: Marts
authors.affiliation: Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States.
authors.forename: Joshua C
authors.initials: JC
authors.lastname: Kaine
authors.affiliation: Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States.
authors.forename: Robert R
authors.identifier: http://orcid.org/0000-0002-9824-944X
authors.initials: RR
authors.lastname: Baum
authors.affiliation: Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States.
authors.forename: Vivien L
authors.initials: VL
authors.lastname: Clayton
authors.affiliation: Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States.
authors.forename: Jami R
authors.initials: JR
authors.lastname: Bennett
authors.affiliation: Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States.
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Cordonnier
authors.affiliation: Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States.
authors.forename: Robert
authors.initials: R
authors.lastname: McCarrick
authors.affiliation: Department of Chemistry, University of Akron , Akron, Ohio 44325, United States.
authors.forename: Abed
authors.initials: A
authors.lastname: Hasheminasab
authors.affiliation: Department of Chemistry, University of Akron , Akron, Ohio 44325, United States.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Crandall
authors.affiliation: Department of Chemistry, University of Akron , Akron, Ohio 44325, United States.
authors.forename: Christopher J
authors.identifier: http://orcid.org/0000-0002-0142-5161
authors.initials: CJ
authors.lastname: Ziegler
authors.affiliation: Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States.
authors.forename: David L
authors.identifier: http://orcid.org/0000-0002-5597-799X
authors.initials: DL
authors.lastname: Tierney