The unusual four coordinate bis(imido) alkene complexes [Mo(NBUt)2(CH2=CHR)(PMe3)] (R = H, Me) have been synthesised via treatment of [Mo(NBUt)2Cl2(dme)] (dme = dimethoxyethane) with two equivalents of RCH2CH2MgCl (R = H, Me) in the presence of PMe3; the molecular structure of the propene derivative is reported.