A 4-center, 6p-conjugated, multiply bonded trigonal-planar complex, [Sb{Cr(CO)(5)}(3)](-) (1), was synthesized via the hydride abstraction of [HSb{Cr(CO)(5)}(3)](2-) (1-H) with HBF4 center dot H2O, with the release of high yields of H-2. The oxidation state of the Sb atom in [Et4N][1] was well-defined as 0, which was evidenced by X-ray 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(CO)(5)}(3)](n-) [1-Nu; n = 2, Nu = H, F, Cl, Br, I, OH; n = 1, Nu = PEt3, PPh3, 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 HBF4 center dot H2O or [CPh3][BF4], 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 [Sb2Cr4Fe2(CO)(28)](2-) (3-Cr) and [HSb2Cr3Fe2(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, [Et4N][1] possessed a low energy gap of 1.13 eV with an electrical conductivity in the range of (1.10-2.77) x 10(-6) S.cm(-1), showing that [Et4N][1] was a low-energy-gap semiconductor. The crystal packing, crystal indexing, and density of states results of [Et4N][1] further confirmed the efficient through-space conduction pathway via the intermolecular Sb center dot center dot center dot O(carbonyl) and O(carbonyl)center dot center dot center dot O(carbonyl) interactions of the 1D anionic zigzag chain of 1.