ABSTRACT
Crystal structures of a series of organic-inorganic hybrid gold iodide perovskites, formulated as A2 [AuI I2 ][AuIII I4 ] [A=methylammonium (MA) (1) and formamidinium (FA) (2)], A'2 [I3 ]1-x [AuI I2 ]x [AuIII I4 ] [A'=imidazolium (IMD) (3), guanidinium (GUA) (4), dimethylammonium (DMA) (5), pyridinium (PY) (6), and piperizinium (PIP) (7)], systematically changed depending on the cation size. In addition, triiodide (I3 - ) ions were partly incorporated into the AuI2 - sites of 3-7, whereas they were not incorporated into those of 1 and 2. Such a difference comes from the size of the organic cation. Optical absorption spectra showed characteristic intervalence charge-transfer bands from AuI to AuIII species, and the optical band gap increased as the size of the cation became larger.
ABSTRACT
A Br-bridged Pd chain complex with the Pd ion in an uncommon +3 oxidation state, [Pd(dabdOH)2Br]Br2 (3), was prepared using a new method involving multiple hydrogen bonds. The PdBr chain complex exhibited superior electrical conductivity and thermal stability. An in-plane ligand with an additional hydrogen donor group (hydroxy group), (2S,3S)-2,3-diaminobutane-1,4-diol (dabdOH), was used to create a multiple-hydrogen-bond network, which effectively shrinks the Pd-Br-Pd distance, stabilizing the Pd(III) state up to its decomposition temperature (443 K). 3 shows semiconducting behavior with quite high electrical conductivity (3-38 S cm-1 at room temperature), which is 106 times larger than the previous record for analogous PdBr chains. Indeed, 3 is the most conductive MX-type chain complex reported so far. The precise positional control of ions via a multiple-hydrogen-bond network is a useful method for controlling the electronic states, thermal stability and conductivity of linear coordination polymers.
