Nickel-ruthenium heterobimetallic complexes of a dinucleating unsymmetrical pincer ligand

We report the first examples of complexes of an unsymmetrical, dinucelating PNNNN ligand containing a PNN pincer pocket and bidentate NN binding pocket. The proton-responsive nature of the pyrazole ligand core allows stepwise synthesis of heterobimetallic complexes via monometallic nickel and ruthenium complexes. Selectivity for the PNN pincer pocket is observed with Ni, whereas complexation to the bidentate NN-pocket is favoured with more sterically encumbered Ru complexes. Heterobimetallic NiFe and NiRu complexes were prepared, with metal-metal distances ranging from 3.7514(8) to 4.5305(9) Å.