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Synthesis and characterization of cationic iron complexes supported by the neutral ligands NP^(i-Pr)_3, NArP^(i-Pr)_3, and NS^(t-Bu)_3^1

MacBeth, Cora E. and Harkins, Seth B. and Peters, Jonas C. (2005) Synthesis and characterization of cationic iron complexes supported by the neutral ligands NP^(i-Pr)_3, NArP^(i-Pr)_3, and NS^(t-Bu)_3^1. Canadian Journal of Chemistry, 83 (4). pp. 332-340. ISSN 0008-4042. http://resolver.caltech.edu/CaltechAUTHORS:20110819-090808091

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Abstract

This paper compares the local geometries, spin states, and redox properties of a series of iron complexes supported by neutral, tetradentate NP_3 (tris(phosphine)amine) and NS_3 (tris(thioether)amine) ligands. Our consideration of an Fe-mediated N_2 fixation scheme similar to that proposed by Chatt for molybdenum motivates our interest in systems of these types. This report specifically describes the synthesis and characterization of cationic Fe(II) chloride complexes supported by the neutral ligands NP^(i-Pr)_3 (NP^(i-Pr)_3 = [N(CH_2CH_2P-i-Pr_2_)3]), NArP^(i-Pr)_3 (NArP^(i-Pr)_3 = [N(2-diisopropylphosphine-4-methylphenyl)_3]), and NS^(t-Bu)_3 (NS^(t-Bu)_3 = [N(CH_2CH_2S-t-Bu)_3]). The solid-state structures, electrochemistry,and magnetic properties of these complexes are reported. Whereas the NPV(i-Pr)_3 and NArP^(i-Pr)_3 ligands provide pseudotetrahedral S = 2 ferrous cations [Fe(NP^(i-Pr)_3)Cl]PF_6 (1[PF_6]) and [Fe(NArP^(i-Pr)_3)Cl]BPh_4 (2[BPh_4]) featuring a long Fe—N bond distance, the NS^(t-Bu)_3 ligand gives rise to a trigonal bipyramidal structure with a S = 1 ground state and a much shorter Fe–N interaction. The complexes 1[BPh_4] and 2[BPh_4] can be reduced under CO to give rise to the five-coordinate Fe(I) monocarbonyls [Fe(NP^(i-Pr)_3)CO]BPh_4 (4[BPh_4]) and [Fe(NAr^(Pi-Pr)_3)CO]BPh_4 (5[BPh_4]). The solidstate structures and electrochemistry of 4[BPh_4] and 5[BPh_4] are described, as is the EPR spectrum of 4[BPh_4]. The synthesis and characterization of the hydride–dinitrogen complex [Fe(NP^(i-Pr)_3)(N_2)(H)]PF_6 (6[PF_6]) has also been accomplished and its properties are also reported.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1139/v05-017DOIUNSPECIFIED
http://www.nrcresearchpress.com/doi/abs/10.1139/v05-017PublisherUNSPECIFIED
Additional Information:© 2005 NRC Canada. Received 9 September 2004. Published on the NRC Research Press Web site at http://canjchem.nrc.ca on 23 March 2005. We acknowledge the DOE (Department of Energy) (PECASE), the NSF (National Science Foundation) (CHE-0132216), and the Beckman Institute Senior Research Fellows Program (CEM) for financial support. Larry Henling and Dr. Michael Day provided crystallographic assistance.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE) Presidential Early Career Award for Scientists and Engineers Awards (PECASE)UNSPECIFIED
NSFCHE-0132216
Beckman Institute Senior Research Fellows Program (CEM)UNSPECIFIED
Subject Keywords:nitrogenase, iron, polydentate phosphines, thioether ligands, N2 chemistry, nitrogen, Fe(I).
Record Number:CaltechAUTHORS:20110819-090808091
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20110819-090808091
Official Citation:Synthesis and characterization of cationic iron complexes supported by the neutral ligands NPi-Pr3, NArPi-Pr3, and NSt-Bu3 Cora E MacBeth, Seth B Harkins, Jonas C Peters Canadian Journal of Chemistry, 2005, 83:332-340, 10.1139/v05-017
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:24954
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:19 Aug 2011 17:01
Last Modified:19 Aug 2011 17:01

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