Neutral and cationic multinuclear half-sandwich rhodium and iridium complexes coordinated to poly(propyleneimine) dendritic scaffolds: Synthesis and cytotoxicity

The development of multinuclear pentamethylcyclopentadienyl (Cp*) rhodium and iridium complexes from first- and second-generation 2-iminopyridyl and salicylaldimine based poly(propyleneimine) dendrimer scaffolds of the type, DAB-(NH2)n (n = 4 or 8, DAB = diaminobutane) has been accomplished. Eight compounds were synthesised, viz. (Cp*MCl)4Gn (1–8), by first reacting DAB-(NH2)n with either 2-pyridinecarboxaldehyde or salicylaldehyde and subsequently metallating the Schiff-base dendrimers with [Cp*MCl2]2 (where M = Rh, Ir). Related mononuclear complexes [Cp*MCl(L)] (L = iminopyridyl or salicylaldimine) (9–12) were obtained in a similar manner. The molecular structures of 9–12 have been determined by single-crystal X-ray diffraction analysis and the in vitro anticancer activities of 1–12 were evaluated against the A2780 and A2780cisR human ovarian carcinoma cell lines.