Inorganic-organic hybrid Cu-dipyridyl semiconducting polymers based on the redox-active cluster [SFe3(CO)9]2-: filling the gap in iron carbonyl chalcogenide polymers.

The construction of sulfur-incorporated cluster-based coordination polymers was limited and underexplored due to the lack of efficient synthetic routes. Herein, we report facile mechanochemical ways toward a new series of SFe3(CO)9-based dipyridyl-Cu polymers by three-component reactions of [Et4N]2[SFe3(CO)9] ([Et4N]2[1]) and [Cu(MeCN)4][BF4] with conjugated or conjugation-interrupted dipyridyl ligands, 1,2-bis(4-pyridyl)ethylene (bpee), 1,2-bis(4-pyridyl)ethane (bpea), 4,4'-dipyridyl (dpy), or 1,3-bis(4-pyridyl)propane (bpp), respectively. X-ray analysis showed that bpee-containing 2D polymers demonstrated unique SFe3(CO)9 cluster-armed and cluster-one-armed coordination modes via the hypervalent µ5-S atom. These S-Fe-Cu polymers could undergo flexible structural transformations with the change of cluster bonding modes by grinding with stoichiometric amounts of dipyridyls or 1/[Cu(MeCN)4]+. They exhibited semiconducting behaviors with low energy gaps of 1.55-1.79 eV and good electrical conductivities of 3.26 × 10-8-1.48 × 10-6 S cm-1, tuned by the SFe3(CO)9 cluster bonding modes accompanied by secondary interactions in the solid state. The electron transport efficiency of these polymers was further elucidated by solid-state packing, X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge spectroscopy (XANES), density of states (DOS), and crystal orbital Hamilton population (COHP) analysis. Finally, the solid-state electrochemistry of these polymers demonstrated redox-active behaviors with cathodically-shifted patterns compared to that of [Et4N]2[1], showing that their efficient electron communication was effectively enhanced by introducing 1 and dipyridyls as hybrid ligands into Cu+-containing networks.

Paramagnetic Semiconducting Se-Mn Clusters: A Mn3Se4-Stabilized Selenide Radical Intermediate and Its Aggregated Derivatives.

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, X-ray photoelectron spectra, electron paramagnetic resonance, and density functional theory 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.

Manganese Telluride Carbonyl Complexes: Facile Syntheses and Exotic Properties-Reversible Transformations, Hydrogen Generation, Paramagnetic, and Semiconducting Properties.

A novel family of five Mn-Te-CO complexes was prepared via facile syntheses: mono spirocyclic [Mn4Te(CO)16]2- (1), four-membered Mn2Te2 ring-type [Mn2Te2(CO)8]2- (2), hydride-containing square pyramidal [HMn3Te2(CO)9]2- (3), and dumbbell-shaped [Mn6Te6(CO)18]4- (4) and [Mn6Te10(CO)18]4- (5). Electron-precise complexes 4 and 5 exhibit unusual paramagnetism arising from two types of Mn atoms in different oxidation states, as determined by X-ray photoelectron spectroscopy, electron paramagnetic resonance, and density functional theory (DFT) calculations. The structural transformations from small-sized Mn4Te 1 and Mn2Te2 2 to the largest Mn6Te10 5 were controllable, the off/on magnetic-switched transformation between HMn3Te2 3 and 5 was reversible, and the magnetic transformation between Mn6Te6 4 and 5 was observed. Interestingly, the reversible dehydridation and hydridation between the HMn3Te2-based cluster 3 and [Mn3Te2(CO)9]- were successfully accomplished, in which the release of a high yield of H2 was detected by gas chromatography. In addition, upon the addition of CO, cluster 3 first forms a carbonyl-inserted intermediate [HMn3Te2(CO)10]2- (3'), detected by the high resolution ESI-MS, which is readily transformed to a dimeric dihydrido cluster [{HMn3Te2(CO)10}2]2- (6) with the introduction of O2. These low- to high-nuclearity complexes exhibit rich redox properties with semiconducting behavior in solids, possessing low but tunable energy gaps (1.06-1.62 eV) due to efficient electron transport via nonclassical C-H···O(carbonyl) interactions. The structural nature, reversible structural transformations, controllable on/off magnetic switches, electron communication networks, and associated chemical properties for hydrogen generation are discussed in detail and supported by DFT calculations, density of states, band structures, and noncovalent interaction analyses.