Add time:09/25/2019         Source:sciencedirect.com

Interaction of dihydropentalene (IV) with trimethylstannyldiethylamide in molar ratios of 1:1 or 1:2 leads to mono- or bis-organotin derivatives of IV, respectively. X-ray analysis of trans(E)-bis(trimethylstannyl)dihydropentalene (Va) has been carried out, R = 3.4%. Molecules of Va are centrosyommetric. The parmeters of monoclinic cell: a 8.680(1), b 7.322(1), c 13.073(2) Å, β 97.74(1)°, space group P21/c, Z = 2. Geometrical parameters of Va have been determined and their values are discussed in comparison with the same parameters for η1-cyclopentadienyl compounds of elements. Chemical shifts 13C, 1H and 119Sn and coupling constants 13C-119Sn and 117Sn-119Sn of bis- and tris-organotin derivatives of IV have been determined. Rapid intramolecular suprafacial metallotropic rearrangement, proceeding as a [1,5]-sigmatropic shift of SnMe3 group, has been found in Va and cis-(Z)-bis(trimethylstannyl)dihydropentalene (Vb). Activation parameters have been evaluated by the analysis of temperature dependence of 13C NMR spectra within the framework of degenerate two-site exchange in the isomers Va and Vb, EA: 42.2±0.9 and 31.2±0.6 kJ · mole−1; ΔH≠298: 39.8±0.9 and 27.7±0.6 kJ · mole−1; ΔS≠298: −6.2±4.0 and −87.0±3.1 J · mole−1 · K−1 and ΔG≠298: 41.6±1.5 and 54.6±1.1. kJ δ mole−1, respectively.

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