Electrochromic behaviour of Ir(iii) bis-cyclometalated 1,2-dioxolene tetra-halo complexes: fully reversible catecholate/semiquinone redox switches

Neutral cyclometalated Ir(iii) complexes of general formula [Ir(ppy)2(O^O)squi], where ppy = 2-phenylpyridine and (O^O)squi = TBC (tetrabromocatechol) or TCC (tetrachlorocatechol) in their semiquinone (squi) monoanionic redox state, were synthesized by chemically oxidizing the anionic parent complexes NBu4[Ir(ppy)2(O^O)cat], in which (O^O)cat represents the corresponding ancillary dioxolene ligand in its dianionic catecholate (cat) redox state. This chemical oxidation leads to the modification of both the photophysical and the magnetic properties of the complexes. While the NBu4[Ir(ppy)2(O^O)cat] complexes are diamagnetic (D) and yellow-orange solids, the corresponding oxidized complexes [Ir(ppy)2(O^O)squi] display paramagnetic (P) properties and are characterized by a dark-green color. The conversion between the two forms (squi vs. cat) is electrochemically and chemically fully reversible. Indeed, the anionic NBu4[Ir(ppy)2(O^O)cat] complexes are quantitatively restored by chemical reduction of the neutral [Ir(ppy)2(O^O)squi] parents. These complexes therefore represent interesting redox based switches between multi-parameter states since they allow switching from a neutral paramagnetic to an anionic diamagnetic form together with a significant change in chromicity. Taking advantage of the significant color difference between the oxidized and the reduced form, an electrochromic cell was prepared with [Ir(ppy)2(TBC)squi] and its spectroelectrochemical properties are reported.

Experimental and theoretical investigation of a metalloreceptor bearing a [Re(CO)3]+ core incorporating a multifunctional ligand: selective reactivity towards Zn2+ and CN− ions

Novel Re(i) complex containing multifunctional ligand HL shows selective reactivity towards Zn²⁺ and CN⁻.

Crystal structure of {(E)-2-[(3,4-di-meth-oxy-phenyl-imino)-meth-yl]phenolato-κ2N,O1}bis-[2-(pyridin-2-yl)phenyl-κ2C1,N]iridium(III) di-chloro-methane disolvate

The asymmetric unit of the solvated title complex, [Ir(C11H8N)2(C15H14NO3)]·2CH2Cl2, consists of two complex mol-ecules together with four di-chloro-methane solvent mol-ecules, one of which is disordered. In each complex mol-ecule, the IrIII ion has a distorted octa-hedral coordination environment defined by two 2-phenyl-pyridine ligands, through two phenyl C and two pyridine N atoms, and by one N,O-bidentate 2-[(2,4-di-meth-oxy-phenyl-imino)-meth-yl]phenolate anion. The IrIII ions lie almost in the equatorial planes with deviations of 0.0396 (17) and 0.0237 (17) Å, respectively, for the two complex mol-ecules. In both complex mol-ecules, the two 2-phenyl-pyridine ligands are nearly perpendicular to each other [dihedral angles between the least-squares-planes of 89.91 (11) and 85.13 (11)°]. In the crystal, inter-molecular C-H⋯O inter-actions as well as inter-molecular C-H⋯π inter-actions are present, leading to a three-dimensional network structure. One of the four dichlormethane solvent mol-ecules shows disorder over two sets of sites [occupancy ratio 0.79 (2):0.21 (2)].