Finally, isotopic patterns observed by ESI-MS were consistent with the formulation {[Pd2(1 DBF )2(2 Py /2 Ph )2](X -)n} (4-n)+ (Fig. and). All told, the spectroscopic data led to the conclusion that successful integrative self-assembly had yielded Pd2L2L'2 heteroleptic assemblies. Disappointingly, all attempts to grow X-ray quality single crystals of the cages were unsuccessful. DFT-optimised structures (Fig. ) of both cis-Pd2L2L'2 cages revealed no extraordinary distortion of the ligand frameworks or Pd(II) coordination environment.