A 4-center, 6π-conjugated, multiply bonded trigonalplanar complex, [Sb{Cr(CO) 5 } 3 ] − (1), was synthesized via the hydride abstraction of [HSb{Cr(CO) 5 } 3 ] 2− (1-H) with HBF 4 •H 2 O, with the release of high yields of H 2 . The oxidation state of the Sb atom in [Et 4 N][1] was well-defined as 0, which was evidenced by Xray photoelectron spectroscopy and X-ray absorption near-edge structure. The distinct color−structure relationship of this low-valent Sb complex 1 toward a wide range of organic solvents was demonstrated, as interpreted by time-dependent density functional theory calculations, allowing the trigonal-planar 1 and the tetrahedral solvent adducts to be probed, revealing the dual acid/base properties of the Sb center. In addition, 1 showed pronounced electrophilicity toward anionic and neutral nucleophiles, even with solvent molecules, to produce tetrahedral complexes [(Nu)Sb{Cr(COCl, Br, I, OH; n = 1, Nu = PEt 3 , PPh 3 , N,N-dimethylformamide (DMF), acetonitrile (MeCN)]. On the contrary, the Fe/Cr hydride complex [HSb{Fe(CO) 4 }{Cr(CO) 5 } 2 ] 2− (2-H) was obtained by treating 1 with [HFe(CO) 4 ] − . Upon hydride abstraction of 2-H with HBF 4 •H 2 O or [CPh 3 ][BF 4 ], a multiply bonded Fe/Cr trigonal-planar complex, [Sb{Fe(CO) 4 }-{Cr(CO) 5 } 2 ] − (2), was produced in which the oxidation coupling Sb 2 -containing complexes [Sb 2 Cr 4 Fe 2 (CO) 28 ] 2− (3-Cr) and [HSb 2 Cr 3 Fe 2 (CO) 23 ] − (3-H) were yielded as final products. Complex 3-Cr exhibited dual Lewis acid/base properties via hydridation and protonation reactions, to form 2-H or 3-H, respectively. Surprisingly, [Et 4 N][1] possessed a low energy gap of 1.13 eV with an electrical conductivity in the range of (1.10−2.77) × 10 −6 S•cm −1 , showing that [Et 4 N][1] was a low-energy-gap semiconductor. The crystal packing, crystal indexing, and density of states results of [Et 4 N][1] further confirmed the efficient through-space conduction pathway via the intermolecular Sb•••O(carbonyl) and O(carbonyl)•••O(carbonyl) interactions of the 1D anionic zigzag chain of 1.