The unprecedented tetrairon dication [{Cp*(dppe)FeC≡C-}4-μ-(1,2,4,5-C6H2)](PF6)2 ( 1 ) was obtained through a sequence of three reactions from 1,2,4,5-tetraethynylbenzene, Cp*(dppe)FeCl (Cp*=C5Me5, dppe=1,2-bis(diphenylphosphino)-ethane), KOtBu, and ferrocenium hexafluorophosphate. The cyclic voltammogram of the target molecule, isolated in 77 % yield, exhibits four well separated and reversible redox events showing that 1 is thermodynamically stable with respect to disproportionation (Kc>106). The tetranuclear dication 1 was characterized by XRD on single crystal, IR and NMR spectroscopies and Mössbauer spectrometry. The experimental data show that 1 behaves as a class II mixed-valence complex with the positive charges preferentially disposed on antipodal positions. This new molecule can be regarded as a potential molecular prototype of quantum dot cellular automata. 相似文献
Coordination of dicobalt hexacarbonyl to the alkyne moiety of norbornene complexes containing either ferrocene or η6‐chlorobenzene‐η5‐cyclopentadienyliron hexafluorophosphate, gave two unique trimetallic complexes available for ROMP. Polymerization of each monomer using Grubbs second generation catalyst gave organoiron/organocobalt polynorbornenes with weight average molecular weights between 55 300 and 69 000 with PDIs between 1.2 and 1.9. Cyclic voltammetric studies of the monomers and polymers at −40 °C showed a reversible reduction for cationic complexes containing η6‐benzene‐η5‐cyclopentadienyliron and for the dicobalt hexacarbonyl moieties while, a reversible oxidation for the ferrocene containing complex was observed. Thermal analysis showed that the cobalt carbonyl moiety of the polymers degraded near 130 °C; however, the polymeric backbone was stable up to 350 °C. Scanning electron microscopy (SEM) and SEM‐EDS indicated that the polymers possessed a fine globular morphology and that the distribution of iron and cobalt atoms was homogenous on the macro‐scale.
The versatility of cationic cyclopentadienyliron complexes is demonstrated for the generation of calix[4]arene‐based dendrimers and polymers. Dendrimers were prepared from a branched organoiron calix[4]arene through subsequent reactions of azo dyes and organoiron complexes. The resulting azo dye‐containing metallocalix[4]arenes were soluble in polar organic solvents and displayed λmax ranging between 430 and 456 nm. Upon addition of various acids, the λmax shifted to higher wavelengths (513–535 nm). In the solid state and in solution, the azo dye‐containing metallocalix[4]arenes reversibly changed colour in the presence of acid and base, indicating their potential use as acid sensors. Cyclic voltammetric studies showed that the iron centres of the metallocalix[4]arenes were reversibly reduced at E1/2 = −1.49 V. When non‐branching organoiron‐based calix[4]arene were reacted with dithiols, polymers containing calix[4]arenes either in their side chains or main chains were obtained. The polymers possessed weight average molecular weights between 35 000 and 53 000. The polymers were determined to be thermally stable with backbone decomposition occurring above 500 °C.
The development of synthesis methods to access advanced materials, such as magnetic materials that combine multimetallic phosphide phases, remains a worthy research challenge. The most widely used strategies for the synthesis of magnetic transition metal phosphides (TMPs) are organometallic approaches. In this study, Fe-containing homometallic dendrimers and Fe/Co-containing heterometallic dendrimers were used to synthesize magnetic materials containing multimetallic phosphide phases. The crystalline nature of the nearly aggregated particles was indicated for both designed magnetic samples. In contrast to heterometallic samples, homometallic samples showed dendritic effects on their magnetic properties. Specifically, saturation magnetization (Ms) and coercivity (Hc) decrease as dendritic generation increases. Incorporating cobalt into the homometallic dendrimers to prepare the heterometallic dendrimers markedly increases the magnetic properties of the magnetic materials from 60 to 75 emu/g. Ferromagnetism in homometallic and heterometallic particles shows different responses to temperature changes. For example, heterometallic samples were less sensitive to temperature changes due to the presence of Co2P in contrast to the homometallic ones, which show an abrupt change in their slopes at a temperature close to 209 K, which appears to be related to the Fe2P ratios. This study presents dendrimers as a new type of precursor for the assembly of magnetic materials containing a mixture of iron- and cobalt-phosphides phases with tunable magnetism, and provides an opportunity to understand magnetism in such materials. 相似文献
The synthesis of linear and star-shaped oligomers containing cationic and neutral organoiron groups in their structures was achieved by reaction of cationic arene complexes of cyclopentadienyliron containing terminal hydroxyl groups with 1,1′-ferrocenedicarbonyl chloride or ferrocene carboxylic acid. The use of chloroarene complexes allowed for the formation of triiron complexes that were subsequently polymerized via nucleophilic aromatic substitution with various oxygen- and sulfur-based dinucleophiles. The corresponding polyethers and thioethers were isolated in good yields and these materials exhibited excellent solubilities in polar organic solvents. Cyclic voltammetric investigations revealed that the cationic iron centers pendent to the polymer backbones underwent reversible reduction steps, while the neutral iron centers within the polymer backbones underwent reversible oxidation steps. Photolysis of these polymers resulted in the removal of the cationic cyclopentadienyliron moieties pendent to the polymer backbones. Thermogravimetric analysis (TGA) revealed that the cationic iron complexes were cleaved from the polymers at approximately 210 °C. Differentials scanning calorimetry (DSC) revealed that the glass transition temperatures of the cationic polymers occurred at higher temperatures than their neutral analogs. 相似文献
Syntheses and properties of the iron bisphosphinoethane complexes FeH2(PP)2 and FeHCl(PP)2[PP?R2PCH2CH2CH2PR2, where R?Me (PP?DMPE), Et(PP?DEPE), and n-Pr (PP?DprPE)] are reported. The complexes can be formed by reduction of the corresponding dichlorides FeCl2(PP)2 with lithium aluminium hydride in THF solution provided that ethanol or more acidic reagents are not employed during the reaction work-up. The dihydrides are notably basic compounds and can be protonated reversibly by alcohols. The dihydrides exist as equilibrating mixtures of cis and trans isomers in solution. The cis isomers of each of the dihydrides are fluxional on the NMR timescale and NMR studies indicate that the interconversion of cis isomers does not necessarily proceed via the trans isomer. 相似文献
FeH(DMPE)2(BH4) [DMPE = 1,2-bis(dimethylphosphino)ethane] is a stable, diamagnetic complex which can be synthesized readily by borohydride reduction of FeH(DMPE)2Cl or by treatment of Fe(DMPE)2H2 with borane. The complex contains an unsupported B? H? Fe hydrogen bridge. Analogous complexes with bulkier ligands, FeH(DEPE)2(BH4), [DEPE = 1,2-bis(diethylphosphino)ethane] and FeH(DPrPE)2(BH4) [DPrPE = 1,2-bis(di-n-propylphosphino)ethane], are less stable. In all complexes, in solution the borohydride ligand undergoes rapid internal motion, with all four boron-bound hydrogens interchanging environments. The barriers for BH4 reorientation (measured by NMR spectroscopy) are in the sequence FeH(DMPE)2(BH)4 > FeH(DEPE)2(BH)4 > FeH(DPrPE)2(BH4). 相似文献
Commercial acrylonitrile butadiene styrene (ABS) polymers are among the most flammable of the currently available range of thermoplastic materials. In addition to having a rather low limiting oxygen index (LOI) value in the range 18.3–18.8, ABS polymers also produce compious amounts of smoke and hazardous gases when burnign in the air. In a recent study directed towards preparing and evaluating compounds which would simultaneously reduce the flammability and smoke produced from burning thermoplastic polymers, a synergistic flame-retarding/smoke-suppressing system based on organoiron compounds has been produced, which when properly compounded into ABS/PVC [poly(vinyl chloride)] blends more than doubles the LOI nad at the same time reduces smoke production significantly. 相似文献