This communication reports the first example of cyclic ferric clusters with an odd number of iron atoms capped by phosphonate ligands, namely, [Fe9(μ-OH)7(μ-O)2(O3PC6H9)8(py)12]. The magnetic studies support a S = 1/2 ground state with an exchange coupling constant of about J ≈ −30 K.
Polymeric two- and three-dimensional, homo- and heterometallic oxalatebridged coordination compounds offer exciting opportunities, mainly in the fields of molecular magnetism and photophysics. Given that a large variety of magnetic phenomena have been reported so far from these molecular magnets, very limited experience is gained from elastic neutron scattering experiments. Therefore, with two examples, we will address the topic of the elucidation of magnetic structures by means of the neutron scattering technique. In addition, due to the possibility of the variation of different metal ions in varying oxidation states, interesting photophysical processes can be observed within the extended three-dimensional host/guest systems.
17 November 2021 in Angewandte Chemie International Edition
Regiospecific C−H activation is a promising approach to achieve extended polymers with tailored structures. While a recent on‐surface synthetic approach has enabled regioselective homocoupling of heteroaromatic molecules, only small oligomers have been achieved. Herein, selective C−H activation for dehydrogenative C−C couplings of hexaazatriphenylene by Scholl reaction is reported for the first time. By combining low‐temperature scanning tunneling microscopy (STM) and atomic force microscopy (AFM), we revealed the formation of one‐dimensional polymers with a double‐chain structure. The details of the growth process are rationalized by density functional theory (DFT) calculations, pointing out a cooperative catalytic action of Na and Ag adatoms in steering the C−H selectivity for the polymerization.