Structural and theoretical studies of intermolecular dihydrogen bonding in [(C6F5)(2)(C6Cl5)B]-H center dot center dot center dot H-[TMP]

The product of the intermolecular 'frustrated Lewis pair' (FLP) B(C6F5)(2)(C6Cl5)/2,2,6,6-tetramethylpiperidine and H-2 has been studied by single-crystal neutron diffraction. This is the first structurally characterised example of a geometrically unconstrained dihydrogen (H center dot center dot center dot H) bond within a hydrogenated FLP system.