Reactions of Bis(2-pyridyl)amine and Its Deprotonated Anion with Ruthenium and Osmium Carbonyl Complexes

The reactions and coordination geometry of
bis(2-pyridyl)amine (Hdpa) and its deprotonated anion
(dpa) can be effectively modified by the reaction conditions. Depending on the solvent system, the reaction of
multinuclear ruthenium carbonyls such as Ru3(CO)12
and [Ru(CO)3Cl2]2 with Hdpa at moderate reaction
temperatures lead to low yields of a monomeric cis(CO),
cis(Cl)-Ru(Hdpa)(CO)2Cl2 or a dimeric metal−metal-bonded [Ru(dpa)2(CO)2]2. In organic solvents high temperatures favor the formation of [Ru(dpa)2(CO)2]2 from
clustered Ru3(CO)12 and Hdpa. The high-temperature
reactions in HCl solution can, in turn, be used for
selective synthesis of cis(CO),cis(Cl)-Ru(Hdpa)(CO)2Cl2.
dpa (deprotonated with CH3Li) readily reacts with
[Ru(CO)3Cl2]2, Ru3(CO)12, or H4Ru4(CO)12 in organic
solvents, leading to [Ru(dpa)2(CO)2]2. Under the corresponding conditions Os carbonyls produce a new type
of dpa-bridged dimer compound without a direct metal−metal bond, [Os(dpa)(CO)2(CH3)]2, in addition to the
ruthenium dimer equivalent [Os(dpa)2(CO)2]2.