A family of mixed ligand complexes of Ru<SUP>II</SUP>-L [L=N-aryl-pyridine-2-aldimine], their reactions, isolation and characterization. X-ray crystal structure of [Ru(pic)(L<SUP>1</SUP>)<SUB>2</SUB>][ClO<SUB>4</SUB>]. CH<SUB>2</SUB>Cl<SUB>2</SUB> [pic= 2-picolinate ion]

Synthesis of the tris-chelated complexes [Ru(L)n(L3)3-n]2+ (L=N-aryl-pyridine-2-aldimine, L3=2-(m-tolylazo)pyridine) based on silver(I) assisted trans-metallation is described. The complexes, [Ru(L)3]2+ and [Ru(L)(L3)2]2+ afford [Ru(pic)(L)2]+ and [Ru(pic)(L3)2]+ (pic= 2-picolinate ion) respectively, on hydrolysis and subsequent oxidation. When RuCl2(L)2 was reacted with two moles of [Ag(L3)2]+, a pink complex of composition [Ru(L)(L3)(L4)]+ [L4=N-aryl-2-picolinamide] was isolated along with the expected brown complex, [Ru(L3)(L)2]2+. Initial oxidation of the metal ion favours L&#8594;L4 conversion. The complexes have been characterized using spectroscopy and X-ray crystallography. The X-ray structure of [Ru(pic) (L1)2]ClO4.CH2Cl2 is reported. The metal oxidation as well as ligand reductions for the complexes have been studied voltammetrically in acetonitrile using platinum as the working electrode. It has been observed that the oxidation of the transformed complexes, viz. [Ru(pic) (L)2]+, [Ru(pic)(L3)2]+ and [Ru(L)(L3)(L4)]+ occur at lower potentials as compared to their parent [Ru(L)n(L3)3-n]2+ complexes. All the complexes show metal-to-ligand charge transfer transitions in the visible range and absorption energies linearly correlate with the differences between the metal oxidation and the first ligand reduction potentials

Monovalent copper complexes of N-aryl-pyridine-2-aldimine. Synthesis, characterization and structure

A direct synthetic route, based on silver(I) assisted metal exchange reaction, to cationic bis-ligand complexes of copper(I) involving N-aryl-pyridine-2-aldimines (L, 1) has been studied. These complexes are obtained as their perchlorates, [Cu(L)2]ClO4 (2). They have been characterized with the help of spectroscopy and X-ray crystallography. The X-ray structure of [Cu(L2)2]ClO4, where L2 is N-p-tolyl-pyridine-2-aldimine is reported. There are two crystallographically independent molecules in the asymmetric unit. The ligand L2 coordinates in a bidentate manner providing a highly distorted tetrahedral geometry about copper. The complexes show highly resolved symmetrical 1H NMR spectra. Intense MLCT absorptions are observed in the visible range. In methanol the CuL22+/CuL2+ couple has E&#189; ca, 0.35 V vs SCE at 298 K. The moderately high positive potential is brought about by the distortion in the geometry of CuL22+

Author Correction:Charge disproportionate molecular redox for discrete memristive and memcapacitive switching (Nature Nanotechnology, (2020), 15, 5, (380-389), 10.1038/s41565-020-0653-1)

Correction to: Nature Nanotechnology. Published online 23 March 2020. In the version of this article initially published, there were presentation errors in the range of y-axis values displayed in Extended Data Figure 4a,b, and Extended Data Figure 5b. The errors have been corrected in the HTML and PDF versions of the article.</p

Isomeric ruthenium(III) complexes of N-phenyl-2-pyridine carboxaldimine. Synthesis, characterization and electron-transfer properties

Three geometric isomers of [RuCl2L2](ClO4) (L=N-phenyl-2-pyridine carboxaldimine) have been isolated by stereoretentive oxidation of the corresponding isomeric ruthenium(II) complexes using Cl2(g) as an oxidant, followed by the addition of aqueous sodium perchlorate. These complexes are paramagnetic (low-spin d5, S= &#189;) and display rhombic EPR spectra at 77 K. The electronic transition energies have been computed, using the observed g values, which agree well with the experimentally observed transitions in the IR region of the optical spectra. In addition to the ligand field transitions, all the complexes also show multiple charge-transfer transitions in the visible region. Each of the complexes display a reversible reductive response due to an RuIII/RuII couple in the range 0.3-0.5 V versus SCE at a platinum electrode. Chemical reductions of these trivalent complexes by hydrazine revert almost quantitatively to the parent bivalent ruthenium complexes. In acetonitrile, RuCl2L2+ complexes act as mild oxidants

An organic approach to low energy memory and brain inspired electronics

10.1063/1.5124155Applied Physics Reviews7

Osmium-promoted oxidative dimerization of aminoarenes to N-aryl-o-arenoquinone diimines (L). Synthesis, structure, electrochemistry, and reactivity of OsBr<SUB>2</SUB>L<SUB>2</SUB>

A family of o-arenoquinone diimine chelates, OsBr2L2 (1, L=N-aryl-o-arenoquinone diimine), were isolated from the reaction of (NH4)2OsBr6 and primary aromatic amines, Ar-NH2. These complexes constitute the first examples of osmium compounds of the o-benzoquinone diimine family. The above oxidative dimerization reaction of Ar-NH2 was authenticated by the X-ray structure determination of a representative example. The X-ray structure of OsBr2L2(R =H) revealed a cis geometry with respect to two coordinated bromides. The bond length trends within the chelate as well as the aromatic rings are consistent with a diimine character of the ligand bound to osmium in its bivalent oxidation state. The complexes showed multiple transitions in near-IR and visible regions. These are electroactive and undergo multiple electron transfer. Three successive voltammetric responses, two oxidative and one reductive, were observed. The potential range was +1.7 to -0.8 V vs SCE in CH3CN solution (Pt electrode). The potentials of the above responses for differently substituted compounds depend on the Hammett &#931;&#963;p parameters of the substitution on L. The EPR spectrum of the electrogenerated 1-electron-oxidized complex 1a+ is described. The electrode potentials of 1 are compared with those of related systems. A qualitative correlation between Os-N bond distances and Os(III)/Os(II) formal potentials for the Os(II) compounds of three different N,N donors is noted. The synthesis of a mixed-ligand tris chelate, [Os(bpy)L2](ClO4)2.H2O, is described, involving the reaction of 1 equiv of 1 with 2 equiv of Ag(bpy)2+. The redox properties of the tris complex are reported. Crystal data for OsBr2L2 (R=H) are as follows: empirical formula C24H20Br2N4Os; crystal system triclinic, space group P&#8593; a=10.464(6) &#197;, b=11.778(6) &#197;, c=12.595(10) &#197; &#945;=103.86(5)&#176;, &#946;=112.72(6)&#176;, &#947;=107.79(4)&#176;; V = 1245.3(10) &#197;3; Z=2; R=4.46%; Rw=5.21%