Cobalt Cyclopentadienyl‐Phosphine Dinitrogen Complexes

By applying the potassium salts of cyclopentadienyl-phosphine ligands LK to CoCl2, the corresponding cobalt chlorides (1, (LCoCl)-Cl-II) were prepared. By reducing complexes 1 with KHBEt3 under a N-2 atmosphere, bridging end-on complexes, LCoI-N-2-(CoL)-L-I (2 a and 2 b), were successfully obtained. N-15(2)-labeled [N-15(2)]-2 a was prepared under N-15(2)/N-14(2) exchange in THF solution. LCoI-N-2-(CoL)-L-I complex 2 a could react with P-4 molecules to release N-2 and generate a Co-P-4-Co moiety 4. Further reduction of complex 2 b led to cleavage of a P-C bond in the cyclopentadienyl-phosphine ligand to provide novel mu-PCy2-bridged Co-0-N-2 complex 5. DFT calculations confirmed the experimental observations.