Abstract The reaction between [Mo (CO) 4 (NO)(ClAlCl 3)] and the sterically hindered diphosphanes (P∩ P) 1, 3-bis (diisopropylphosphanyl) propane (dippp, a), 1, 2-bis ( diisopropylphosphanyl) ethane (dippe, b), 1, 1′-bis (diisopropylphosphanyl) ferrocene (dippf, c) and 1, 2-bis (dicyclohexylphosphanyl) ethane (dcype, d) produced the chlorides [Mo (P∩ P)(CO) 2 (NO) Cl](1a–1d), which were transformed into the corresponding ...