Comparative theoretical study of [3+2] and [2+2] cycloadditions of ethylene and WXYMe2; X, Y = (double bond; length as m-dashO), (double bond; length as m-dashNH), (double bond; length as m-dashCH2)

Quantum chemical calculations employing density functional theory (B3LYP) were carried out to compare the preference of [3+2] versus [2+2] cycloadditions of ethylene to WO2(CH3)2 (W2), WONH(CH3)2 (W3), WNHCH2(CH3)2 (W4), W(CH2)2(CH3)2 (W5), and W(NH)2(CH3)2 (W6). The results are compared to previously published data on the related tungsten complex WOCH2(CH3)2 (W1). In agreement with MoOCH2(CH3)2 and ReO2CH3CH2, all six tungsten complexes prefer a [2+2] pathway rather than a [3+2] cycloaddition which is the reverted preference compared to the analogous compounds TcO2CH3CH2, MnO2CH3CH2, RuO3CH2, OsO3CH2 and OsO2(NH)2, and MO2CH3CH2 (M = Ir, Rh, Co).