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Issue 20, 2008
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Experimental and theoretical aspects of the haptotropic rearrangement of diiron and diruthenium carbonyl complexes bound to 4,6,8-trimethylazulene

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Abstract

The haptotropic rearrangement of dinuclear metal carbonyl species on the conjugate π-ligand of (μ235-4,6,8-trimethylazulene)M2(CO)5 [M = Fe (3) and Ru (4)] was investigated in detail both experimentally and theoretically. The complexes, 3 and 4, were synthesized and characterized by spectroscopy and crystallography. The spin saturation transfer technique of 1H NMR was used to measure the rate constant k of the haptotropic isomerization between the two enantiomers of 3 and 4, from which thermodynamic parameters were determined: (3; ΔS = −7 ± 1 cal K−1 mol−1, ΔH = 22 ± 1 cal mol−1, ΔG373 = 25 ± 1 cal mol−1), (4; ΔS = 7 ± 1 cal K−1 mol−1, ΔH = 25 ± 1 cal mol−1, ΔG373 = 23 ± 1 cal mol−1). DFT calculations (the B3LYP, B1B95 and PBE1PBE methods) were also carried out using the CEP-31G and cc-pVDZ as the basis set of the transition metal and other elements, respectively, by which both ground state and transition state structures were optimized for the haptotropic rearrangement of 3 and 4. The potential energy surface for these reactions suggests that the reaction involves the conversion of the coordination mode from μ235- (ground state) to μ215- (transition state). Mechanistic consideration, in particular that of differences in transition states between the diiron and diruthenium complexes, is also described.

Graphical abstract: Experimental and theoretical aspects of the haptotropic rearrangement of diiron and diruthenium carbonyl complexes bound to 4,6,8-trimethylazulene

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Publication details

The article was received on 14 Dec 2007, accepted on 14 Feb 2008 and first published on 25 Mar 2008


Article type: Paper
DOI: 10.1039/B719331A
Citation: Dalton Trans., 2008,0, 2708-2716
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    Experimental and theoretical aspects of the haptotropic rearrangement of diiron and diruthenium carbonyl complexes bound to 4,6,8-trimethylazulene

    K. Tsuchiya, K. Ideta, K. Mogi, Y. Sunada and H. Nagashima, Dalton Trans., 2008, 0, 2708
    DOI: 10.1039/B719331A

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