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255ChemInform Abstract The reaction of ethyl chloroformate (II) with the (phosphoryl)lithium complex (I) yields the corresponding 1-(ethoxycarbonyl)phosphole complex (III). On reaction with dimethyl acetylenedicarboxylate (IV), (III) gives the 7-phosphanorbornadiene complex (V) which is a good precursor for the transient (ethoxycarbonyl)phosphinidene complex EtOCO-P=W(CO)5. This transient species cleanly reacts with MeOH (VI), diethylamine (VII), and tolan (IX) to afford the expected phosphinite (VIII) and phosphirene complexes (X). However, it appears impossible to convert the P-COOEt into the P-H unit. In order to vary the P-substituent in the transient phosphinidene complexes, the 1-cyanophosphole complex (XII) is prepared according to the scheme. This provides for the first time an easy access to 1-alkoxy-, 1-amino-, 1-aryl-, and 1-alkynyl-3,4-dimethylphosphole complexes such as (XIV). Using the same basis scheme as with the ethoxycarbonyl substituent, it is possible to prepare from these new phospholes (XIVa) and (XIVb) the corresponding 7-phosphanorbornadiene complexes, precursors of R2-P=W(CO)5, and their products (XV) and (XVI) from the reaction with tolan or MeOH.