No abstract

No abstract

Recently we had reported the noninnocent behavior of 1,1'-bis(diphenylphosphino)ferrocene (dppf) in Fe(CO)dppf [Ringenberg et al., Inorg. Chem., 2017, 56, 7501]. Moving to the left in the periodic table, HMn(CO)(dRpf) where dRpf = dppf (1H) and 1,1'-bis(diisopropylphosphino)ferrocene (dippf) (2H) were synthesized. The hydride ligand was removed by protonation with [(EtO)H][B(Ar)] ([B(Ar)] = tetrakis[3,5-bis(trifluoromethyl)phenyl]borate), resulting in the rapid evolution of H followed by the formation of an Fe→Mn interaction. The reaction mechanism was determined by in situ IR experiments which show that directly following protonation both [1] and [2] offer an open manganese coordination site that allows for the formation of an intramolecular Fe→Mn dative bond. This process is significantly faster for [2] than for [1]. The reduction chemistry as studied by cyclic voltammetry (CV) reveals that both complexes change from a distorted octahedral coordination with an Fe→Mn interaction to an open square-pyramidal configuration which is more stable for [1] than [2]. Reoxidation of this square-pyramidal species proceeds more reversibly for 2 versus 1 due to the faster ferrocene ligand reorganization. The electrochemical mechanism was studied by in situ spectroscopic techniques, e.g., IR, UV-vis-NIR (near IR), and EPR spectroelectrochemistry (SEC) as well as by CV simulation. The new complexes described offer an exciting platform for the development of electrocatalysts for the reduction of CO to CO, or for proton reduction (2H + 2e → H).

The primary use of poly(acrylonitrile) (PAN) fibers, commonly referred to as acrylic fibers, is in textile applications like clothing, furniture, carpets, and awnings. All commercially available PAN fibers are processed by solution spinning; however, alternative, more cost‐effective processes like melt spinning are still highly desired. Here, the melt spinning of PAN‐co‐poly(methyl acrylate) (PMA) plasticized with propylene carbonate (PC) at 175°C is reported. The use of methyl acrylate (MA) as comonomer and PC as an external plasticizer renders the approach a combination of internal and external plasticization. Various mixtures of PAN and PC used in this work were examined by rheology, subjected to melt spinning, followed by discontinuous and continuous washing, respectively. The best fibers were derived from a PAN‐co‐PMA copolymer containing 8.1 mol‐% of MA having a number‐average molecular weight M n of 34 000 g/mol, spun in the presence of 22.5 wt.‐% of PC. The resulting fibers were analyzed by scanning electron microscopy and wide‐angle X‐ray scattering (WAXS), and were subjected to mechanical testing.