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  • Synthesis, structural characterization and NMR studies of group 10 metal complexes with macrocyclic amine N-heterocyclic carbene ligands
Title: Synthesis, structural characterization and NMR studies of group 10 metal complexes with macrocyclic amine N-heterocyclic carbene ligands
A series of Ni( ii ), Pd( ii ) and Pt( ii ) complexes [ML][PF 6 ] 2 [L = L 1 , M = Ni ( 1 ), Pd ( 2 ), Pt ( 3 ); L = L 2 , M = Ni ( 4 ), Pd ( 5 ), Pt ( 6 )] and [Pt(L 2 )(acac)] ( 7 ) have been prepared by the reactions of two tetradentate macrocyclic amine-NHC ligand precursors, [H 2 L 1 ][PF 6 ] 2 and [H 2 L 2 ][PF 6 ] 2 , with Ni(OAc) 2 ·4H 2 O, Pd(OAc) 2 and Pt(acac) 2 in the presence of NaOAc. Complex 7 is isolated along with 6 from the same reaction between [H 2 L 2 ][PF 6 ] 2 and Pt(acac) 2 . There are two atropisomers in 1–3 and two achiral conformers in 4–6 . The crystal structures of 1–3 and one conformer of 4–6 ( 4a–6a ) have been determined by single-crystal X-ray diffraction studies. The metal ion is found to reside in the cavity of the macrocyclic ring and adopts a square-planar configuration. Detailed NMR studies including variable-temperature NMR spectroscopy reveal a dynamic interconverting process between two atropisomers of 1–3 in the solutions via a ring twisting mechanism. Two conformers in the equilibrated solution of 4–6 , probably arising from the orientation of two amine N–H bonds with respect to the coordination plane, exchange slowly. Time-dependent 1 H NMR spectra show that one conformer ( 4a–6a ) in solution converts into the other ( 4b–6b ) via the inversion of the nitrogen atom.  more » « less
Award ID(s):
1633870
NSF-PAR ID:
10062481
Author(s) / Creator(s):
; ; ; ; ; ;
Date Published:
Journal Name:
Dalton Transactions
Volume:
47
Issue:
12
ISSN:
1477-9226
Page Range / eLocation ID:
4282 to 4292
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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