The metallophosphaalkene (h5-C5Me5)(CO)2FeP:C(NMe2)2 (I) undergoes reaction with dialkyl azodicarboxylates RO2CN:NCO2R (R = CMe3, Et, CH2Ph) to afford complexes II (R = CMe3, Et, CH2Ph) with the novel chelating 3-(tetramethylcyclopentadienyl)-1-phospha-2-propenyl ligand. This ligand system results from a yet unprecedented azocarboxylate-induced condensation of a ring Me substituent with the methylene phosphine fragment of educt I. The mol. structure of II (R = CH2Ph) (P21/c, a = 10.522(3) .ANG., b = 22.124(9) .ANG., c = 12.806(4) .ANG., b = 101.58(3) Deg) was detd. by single-crystal x-ray anal.