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Syntheses and characterization of hepta-coordinated Group 4 amidinate complexes

Abstract

Tri-amidinate chloride complexes M[MeC(NiPr)2]3Cl [M = Zr (1), Hf (2)] have been prepared from MCl4 and lithium amidinate Li[MeC(NiPr)2]. The uncommon hepta-coordinated complexes Zr-Cl (1) and Hf-Cl (2) undergo metathesis reactions with 1 equiv. of MeLi and EtMgCl to give alkyl derivatives M[MeC(NiPr)2]3R [R = Me, M = Zr (3), Hf (4); R = Et, M = Zr (5), Hf (6)]. The dynamic behaviors of Zr-Cl (1) and Hf-Cl (2) in solution have been studied using variable-temperature 1H NMR (VT 1H NMR), giving activation parameters ΔH, ΔS, and ΔG for several exchange processes in Zr-Cl (1) and Hf-Cl (2). 1H-15N gHMBC NMR spectroscopy gives the chemical shifts of the N atoms in 1-6. The 1H-15N gHMBC NMR spectra of 1-4 at elevated temperatures are needed to obtain signals. Crystal structures of Zr-Cl (1), Hf-Cl (2), Zr-Et (5), and Hf-Et (6) have been determined via X-ray diffraction. DART-MS studies of Zr-Cl (1) and Hf-Cl (2) in air give MS of 1-2, cations M[MeC(NiPr)2]3+ [M = Zr (7), Hf (8)], and hydroxyl complexes M[MeC(NiPr)2]3OH [M = Zr (9), Hf (10)]. In comparison, DART-MS spectra of 3-6 in air show only 7-8 and 9-10, indicating lability of the alkyl ligands and/or their fast hydrolysis by the moisture.

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Publication details

The article was received on 21 Jun 2018, accepted on 13 Jul 2018 and first published on 13 Jul 2018


Article type: Paper
DOI: 10.1039/C8DT02523A
Citation: Dalton Trans., 2018, Accepted Manuscript
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    Syntheses and characterization of hepta-coordinated Group 4 amidinate complexes

    T. M. Cook, C. A. Steren and Z. Xue, Dalton Trans., 2018, Accepted Manuscript , DOI: 10.1039/C8DT02523A

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