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 <i>via</i> 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.