The novel hydroxo-bridged dimeric lead-chromium carbonyl complex [Et4N](2)[{PbCr2(CO)(10)}(2)(mu-OH)(2)] ([Et4N](2)[1]) was synthesized from the reaction of PbCl2 and Cr(CO)(6) followed by metathesis with [Et4N]Br in a KOH/MeOH solution. The X-ray crystallographic structure shows that dianion 1 consists of two Pb{Cr(CO)(5)}(2) units bridged by two hydroxo fragments in which the Pb atoms are further coordinated with two Cr(CO)(5) groups, resulting in a distorted tetrahedral geometry. A CO2 molecule can insert itself into dianion 1 to form two new carbonate complexes, [Et4N](2)[{PbCr2(CO)(10)}(CO3)]([Et4N](2)[2]) and [Et4N](2)[{PbCr2(CO)(10)}(2)(CO3)] ([Et4N](2)[3]), depending on the reaction conditions. In addition, complex 2 can be transformed into 3 in CH2Cl2 solution at an elevated temperature. While the carbonate group in dianion 2 is bonded to one Pb atom, which is coordinated with two Cr(CO)(5) fragments, the carbonate group in 3 bridges the two Pb centers in a mu-1 kappa(OO)-O-2':2 kappa(OO)-O-2' fashion in which each Pb atom is further bonded to two Cr(CO)(5) moieties. Complexes 2 and 3 can be converted back the hydroxo complex 1 under appropriate conditions. All three unprecedented lead-chromium compounds, 1-3, were fully characterized by spectroscopic methods and single-crystal X-ray diffraction analyses. The nature and formation of complexes 1-3 were also examined by molecular orbital calculations using the B3LYP method of the density functional theory.