1,2-Metallotropic shifts in trimethylplatinum(IV) and tricarbonylrhenium(I) halide complexes of pyridazine and 4-methylpyridazine

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J.-Chem.-Soc.-Dalton-Trans.-1994-445-455 Download

Type of publication: Journal paper

Abstract: Pyridazine (pydz) and 4-methylpyridazine (4Me-pydz) form stable bis(monodentate) complexes of general formulae fac-[PtXMe3L2](X = Cl, Br or I) and fac-[ReX(CO)3L2](X = Cl, Br or I). These complexes in above-ambient temperature solutions exhibit 1,2-fluxional shifts between the nitrogen donor pairs of each ring. All linkage isomers of the pydz complexes are equivalent whereas three NMR-distinct linkage isomers, namely (1,1) (1,2)/(2,1) and (2,2) species, occur in solutions of the 4Me-pydz complexes. Fluxional exchange kinetics have been measured by variable-temperature 1H NMR bandshape analysis and two-dimensional exchange spectroscopy (EXSY). Platinum-195 NMR data have been obtained for the complexes [PtXMe3(4Me-pydz)2](X = Br or I) and their fluxional dynamics investigated by 195Pt two-dimensional EXSY and total bandshape analysis. Energy barriers, ΔG‡(298.15 K) for the 1,2-M–N fluxion are in the ranges 69–74 kJ mol–1 for the PtIV complexes and 84–90 kJ mol–1 for the ReI complexes. The crystal structure of [PtClMe3(pydz)2] shows the cis pydz rings oriented in a propeller arrangement with their unco-ordinated nitrogens oriented away from the cis positioned chlorine.

Published URL: https://pubs.rsc.org/en/content/articlelanding/1994/dt/dt9940000445

Date Published: January 1 1994

Publication title: 1 2-Metallotropic shifts in trimethylplatinum(IV) and tricarbonylrhenium(I) halide complexes of pyridazine and 4-methylpyridazine

Publisher: Dalton Transactions

Pages: 445-455

Subject(s): Chemistry

DOI: DOI https://doi.org/10.1039/DT9940000445

Keywords: trimethylplatinum | tricarbonylrhenium | halide complexes | pyridazine | 4-methylpyridazine