含十五族與十六族之過渡金屬羰基團簇物及聚合物之合成與相關應用研究(3/3)

The transition metal-stabilized heavy main group radicals are extremely scarce due to their highly reactive natures, making them difficult to be isolated and identified. We report here a rare class of the Se radical-containing manganese carbonyl anionic cluster, [(μ-Se)(μ3-Se2)2Mn3(CO)9]‧2? (1), which was successfully obtained from the one-pot reaction of Se powder and Mn2(CO)10 in concentrated KOH/MeOH/MeCN solutions at 90 °C. Dianion 1 and its dimeric cluster, [(μ4-Se2){(μ3-Se2)2Mn3(CO)9}2]4? [(1)2], could undergo the reversible Se?Se bond breakage or reformation by the thermal cracking of (1)2 or self-dimerization of 1, showing the μ-Se‧? radical character of 1. Complex 1 could react with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) to form the Se radical-captured complex [(μ-Se(TEMPO))(μ3-Se2)2Mn3(CO)9]2? (1-TEMPO) or could react with alkylene bromides (CH2)nBr2 (n = 1, 2) to give the Mn4-based oxidative coupling products, [(μ4-Se2)(μ-Se2LSe)2Mn4(CO)12]2? (L = CH2, 2-CH2; Se, 2-Se). In addition, dianion 1 and its aggregated derivatives (1)2, 1-TEMPO, 2-CH2, and 2-Se exhibited unusual paramagnetic properties with the spin-state switching from S = 1 (Mn) + 1/2 (Se) to S = 1 (Mn), in which their magnetic centers were proved to be mixed-valent Mn atoms and the μ-Se‧? radical, as evidenced by Evans method, superconducting quantum interference device (SQUID), X-ray photoelectron spectra (XPS), electron paramagnetic resonance (EPR), and density functional theory (DFT) calculations. Importantly, these clusters showed semiconducting behaviors with low and tunable energy gaps (1.50?2.01 eV) and varied electrical conductivities (2.52×10?8?4.58×10?9 S/cm), where efficient electron transports mainly arose from C?H(phenyl)···O(carbonyl) interactions within the solid-state frameworks. System II: Sb?Cr?CO Clusters Two novel chromium carbonyl-stabilized polyantimony Zintl clusters, [(μ6-Sb4)Cr6(CO)28]4? (1) and [(μ6-Sb12)Cr6(CO)28]4? (2), were obtained from reactions of Sb2O3 and Cr(CO)6 in concentrated KOH/MeOH solutions under refluxing conditions. X-ray analysis showed that 1 consisted of an intact Sb4 tetrahedral core coordinated by four terminal Cr(CO)5 fragments and two Cr(CO)4 moieties at two opposite Sb–Sb edges. Cluster 2 displayed a central Sb12 core, in which the four outward Sb atoms were bound with four Cr(CO)5 and bridged by two Cr(CO)4 fragments to give a di-Sb6Cr-norbornadiene-fused structure. Surprisingly, clusters 1 and 2 exhibited paramagnetic properties with S = 1 on the bridging [Cr(CO)4]2? fragments, as evidenced by SQUID, EPR, XPS, XANES, and DFT calculations. In addition, complex 1 was found to react with Mn(CO)5Br, Mn2(CO)10, Fe(CO)5, and Co2(CO)8, producing transmetallated complexes, mono- or di-Mn(CO)4-substituted complexes [(μ6-Sb4)Cr5Mn(CO)28]3? (1-Mn) or [(μ6-Sb4)Cr4Mn2(CO)28]2? (1-Mn2), distorted cubic cluster [(μ4-Sb)4Cr2Fe6(CO)30]4? (1-Fe), and metal?metal-bonded cubic complex [(μ4-Sb)2(μ6-Sb2)Cr4Co4(CO)31]2? (1-Co), respectively. Complex 1 could also be oxidized by [Cu(MeCN)4]+ or O2, forming the Sb4 chain-bonded trigonal prismatic cluster [(μ6-Sb4)Cr6(CO)28]2? (3) or a di-O-bridged complex [(μ6-Sb4O2)Cr6(CO)28]4? (1-O2), in which the reduction of 3 with Na2Fe(CO)4 to tetrahedral cluster 1 was successfully achieved. These transmetallated complexes 1-Mn, 1-Fe, and 1-Co and the O2-activated product 1-O2 exhibited paramagnetic properties with S = 1 or S = 2 for 1-O2, where the magnetic centers were located on the introduced metal fragments. Finally, all the polyantimony-containing metal carbonyl complexes exhibited semiconducting behaviors with optical energy gaps of 1.26–1.63 eV and semiconductivity of 4.84×10?10 S/cm (1), indicative of efficient electron transport in the solid state.