Dinitrogen activation by a phosphido-bridged binuclear cobalt complex

By reacting the semi-rigid PNP ligand with CoBr2, the corresponding complex PNPCoBr (1) was obtained. The reduction of 1 with excess amounts of KC8 in THE under a N-2 atmosphere yielded a binuclear cobalt dinitrogen anion complex [Co(mu-Cy2P)PCyN2](2)K (2) via the C-P bond cleavage of the PNP ligand. By adding 2,2,2-cryptand into complex 2, an ion pair Co complex, [Co(mu-Cy2P)PCyN2](2)K(crypt-222) (3), could be effectively prepared. The structures of 1, 2, and 3 have been determined by single-crystal X-ray diffraction analysis, and N-2 is moderately activated in complexes 2 and 3. There is a Co-Co bond in 2 and 3 suggested by DFT calculations. Compounds 1 and 2 display catalytic activity for the transformation of N-2 into N(SiMe3)(3).

Automated summary

By reacting semi-rigid PNP ligand with CoBr2, complex PNPCoBr (1) was obtained. The reduction of 1 with excess amounts of KC8 in THE under a N-2 atmosphere yielded binuclear cobalt dinitrogen anion complex [Co(mu-Cy2P)PCyN2](2)K (2) by cleaving the C-P bond of the PNP ligand. Adding 2,2,2-cryptand into complex 2 effectively prepared ion pair Co complex, [Co(mu-Cy2P)PCyN2](2)K(crypt-222) (3). The structures of 1, 2, and 3 were determined by single-crystal X-ray diffraction analysis, and N-2 is moderately activated in complexes 2 and 3. DFT calculations suggest the presence of a Co-Co bond in 2 and 3. Compounds 1 and 2 exhibit catalytic activity for the transformation of N-2 to N(SiMe3)(3).