Base-assisted reduction of [Ru(CO)3Cl2]2 in the presence of NP-Me2 (2,7-dimethyl-1,8-naphthyridine) in thf provides an unsupported diruthenium(I) complex [Ru2(CO) 4Cl2(NP-Me2)2] (1). Two NP-Me 2 and four carbonyls bind at equatorial positions and two chlorides occupy sites trans to the Ru-Ru single bond. Reaction of [Ru(CO) 3Cl2]2, TlOTf, KOH and NP-Me2 in acetonitrile, in a sealed container, affords a bicarbonate bridged diruthenium(I) complex [Ru2(CO)2(μ-CO) 2(μ-O2COH)(NP-Me2)2](OTf) (2). The in situ generated CO2 is the source for bicarbonate under basic reaction medium. Isolation of 2 validates the decarboxylation step in the base-assisted reduction of [RuII(CO)3Cl2] 2 → [RuI2(CO)4]2+. © 2011 Elsevier B.V. All rights reserved.