Reversible halide-modulated nickel-nickel bond cleavage: metal-metal bonds as design elements for molecular devices.

The synthesis and study of basic molecular devices are active areas of research aimed toward understanding the fundamental design and functional parameters required for the construction of complex molecular machines.[1] Transition metals have been used extensively in this context in conjunction with elegantly designed ligand frameworks.[2] Typically, transition metals bind to different sets of donors in these frameworks, inducing large molecular motions, as a function of changes in pH,[3] redox processes,[4] excitation by light,[5] heating,[5] introduction of additional ligands,[3] and removal or addition of different metal ions.[6] We report herein strategies based on chloride-mediated Ni-Ni and thermally accessible Ni-P bond cleavage to construct molecular analogues of hinge and mechanical crank mechanisms.