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Issue 22, 2000
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Dynamic NMR investigations of fluxionality of 2-(dimethoxymethyl)pyridine and 2,6-bis(dimethoxymethyl)pyridine in rhenium(I) and platinum(IV) complexes

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Abstract

The ligands 2-(dimethoxymethyl)pyridine (L1) and 2,6-bis(dimethoxymethyl)pyridine (L2) formed bidentate chelate complexes with the isoelectronic transition metal moieties ReIX(CO)3 and PtIVXMe3 (X = halide). The complexes [ReX(CO)3L1] (X = Cl or Br), [PtXMe3L1] (X = Br or I) and [ReBr(CO)3L2] in organic solvents were shown by NMR to undergo fluxional processes which interconvert co-ordinated and pendant OMe groups. Rates and activation energies of these fluxions were measured by NMR methods (1-dimensional bandshape analysis or 2-dimensional exchange spectroscopy). Magnitudes of ΔG (298.15 K) for the fluxions were in the range 59–85 kJ mol−1 with the order being ReI–L1 > ReI–L2 > PtIV–L1. A carbon–carbon bond rotation mechanism is proposed for the fluxions in the L1 complexes and concerted C–C bond rotation/metallotropic shift processes for the L2 complexes. Crystal structures of [ReCl(CO)3L1] and [PtIMe3L1] revealed distorted octahedral metal centres with N–M–O ‘bite’ angles of 73–75° and a trans relationship of the axial halide and pendant OMe group.

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Article information


Submitted
19 Jul 2000
Accepted
11 Sep 2000
First published
24 Oct 2000

J. Chem. Soc., Dalton Trans., 2000, 4218-4226
Article type
Paper

Dynamic NMR investigations of fluxionality of 2-(dimethoxymethyl)pyridine and 2,6-bis(dimethoxymethyl)pyridine in rhenium(I) and platinum(IV) complexes

M. L. Creber, K. G. Orrell, A. G. Osborne, V. Šik, M. B. Hursthouse and K. M. Abdul Malik, J. Chem. Soc., Dalton Trans., 2000, 4218
DOI: 10.1039/B005821L

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