Coordination of Piano‐Stool Complexes to a Hydrogen‐Bonded Rosette‐Type Assembly

Abstract

A new melamine (ME)–barbituric acid (BA) rosette‐type system has been prepared and characterized. The introduction of a pyridyl group on the barbituric acid moiety allows coordination of metal ions at the periphery of the ME3·BA3 rosette. Reactions of 1.5 equiv. of [Ru(cym)Cl2]2 (cym = p‐cymene) or [M(Cp*)Cl2]2 (Cp* = pentamethylcyclopentadienyl; M = Rh, Ir) with the rosette afford the corresponding ME3·[BA{Ru(cym)Cl2}]3 and ME3·[BA{M(Cp*)Cl2}]3 assemblies. The neutral metal‐containing rosettes ME3·[BA{Ru(cym)Cl2}]3 and ME3·[BA{Rh(Cp*)Cl2}]3 can also be obtained by adding the mononuclear complexes [BA{Ru(cym)Cl2}] and [BA{Rh(Cp*)Cl2}] to N,N′‐bis(4‐tert‐butylphenyl)melamine in chloroform. In addition, the triphenylphosphine derivatives [Ru(cym)(PPh3)Cl2] or [M(Cp*)(PPh3)Cl2] react with ME3·BA3 in the presence of silver triflate to generate the ionic rosette‐type assemblies ME3·[BA{Ru(cym)(PPh3)Cl}+]3·3CF3SO3– and ME3·[BA{M(Cp*)(PPh3)Cl}+]3·3CF3SO3–, respectively.