Metal‐Directed Synthesis and Photophysical Studies of Trinuclear V‐Shaped and Pentanuclear X‐Shaped Ruthenium and Osmium Metallorods and Metallostars Based upon 4′‐(3,5‐Dihydroxyphenyl)‐2,2′:6′,2′′‐terpyridine Divergent Units

A new series of V‐shaped trinuclear metallorods and X‐shaped pentanuclear metallostars has been prepared by the reaction of metal complexes bearing pendant phenolic functionalities with complexes containing electrophilic ligands. Specifically, {M(tpy) 2 } motifs (M=Ru or Os; tpy=2,2′:6′,2′′‐terpyridine) bearing one or two pendant 3,5‐dihydroxyphenyl substituents at the 4‐position of the central ring of the tpy have been reacted with the complexes [Ru(tpy)(Xtpy)] 2+ (X=Cl or Br) to form new ether‐linked species. The energy transfer from ruthenium to osmium in these complexes has been investigated in detail and the efficiency of transfer shown to be highly temperature dependent; the energy transfer is highly efficient at low temperature, whereas at room temperature nonradiative and nontransfer deactivation of the excited {Ru(tpy) 2 }* domains is most significant.