H2O In Methanol Research Articles

Reactions at the N2Ni(μ2-SR)2NiN2 Core in Dinuclear Nickel(II) Amine-Thiolate Complexes

A discrete dinickel complex with a central N2NiII(μ2-SR)2NiIIN2 core has been synthesized and investigated in the context of ligand binding and oxidation state changes. Reaction of the hexadentate amine-thiolate ligand N,N′-bis-[2-thio-3-aminomethyl-5-tert-butylbenzyl]propane-1,3-diamine (8) with Ni(ClO4)2 · 6 H2O in methanol affords [NiII28][ClO4]2 · 3 CH3OH (9), the structure of which has been determined by X-ray crystallography. Complex 9 contains a central N2Ni(μ2-SR)2NiN2 core with two approximately planar cis-N2S2Ni coordination polyhedra bridged at the thiolate sulfur atoms. The cis-N2S2Ni units differ in that one nickel atom forms a six-membered chelate ring with the two secondary amine nitrogen atoms of 8 whereas the other nickel atom is bound to the remaining primary nitrogen atoms. Complex 9 binds a variety of substrates. Binding of anions to the N2Ni(μ2-SR)2NiN2 core in 9 occurs selectively at the Ni atom bound to the secondary nitrogen atoms because of a slightly weaker ligand-field strength. This is demonstrated by X-ray structure determination of the isothiocyanate complex [NiII28(NCS)2] · MeOH (10) formed by the reaction of 9 with 2 equiv. of KSCN in methanol. Complex 10 is the first example of a complex with adjacent octahedral cis-N4S2Ni and planar cis-N2S2Ni sites. The overall dinuclear structure of the parent complex 9 is retained in 10, except for trans-axially bound isothiocyanate ions at Ni(1) and an as yet unexplained inversion of configuration at both secondary amine nitrogen atoms. In DMF solution both complexes undergo two successive reductions at potentials of –0.95 V and –1.53 V vs SCE, assigned to the formation of mixed-valent [NiINiII8]1+ and [NiI28]0 species, respectively. The similar electrochemical properties of 9 and 10 suggest that the trans-axially bound isothiocyanate ions in 10 are replaced by DMF molecules in DMF solution. Upon reduction, these solvent molecules decoordinate to produce an unsolvated [NiINiII8]1+ species with two planar N2S2Ni units.

Selective electrosynthesis of p-methoxybenzaldehyde at spinel type CoMn2O4/titanium-composite anodes

Activated titanium anodes with a spinel coating of CoMn2O4 of about 1μm thickness were developed. A relative stability in acid electrolytes was found. The novel anode was employed for the anodic oxidation of p-methoxytoluene (PMT) to p-methoxybenzaldehyde (PMB), which is of industrial interest. Batch type electrolyses with 30% theoretical conversion (4Fmol−1) were used for␣a parametric screening. The solvent/electrolyte-system was 1m H2SO4/5m H2O in methanol. Optimum results (60% selectivity, 50–60% current efficiency) were obtained at low concentrations of the educt (0.2m). A part of the current is consumed for the formation of the benzylmethylether, which can be further oxidized to PMB. It was proved that the novel anode operates according to the mechanism of heterogeneous redox catalysis with ter- and heptavalent manganese as the redox species. A turnover factor of >2000 is unusual for a spinel in acid solution.

Thermodynamic properties of water/organic systems with small contents of water 1. Limiting partial molal volumes of D2O and H2O in methanol and 2-propanol at various temperatures

Limiting partial molal volumes of D2O and H2O in methanol and 2-propanol have been measured in the temperature interval 278–318 K. A hypothesis is advanced regarding the formation of water-alcohol aggregates.

ChemInform Abstract: Valence Trapping in Mixed‐Valence Mn(II)Mn(III) Complexes of a Macrocyclic Binucleating Ligand.

AbstractThe template reaction of 1,3‐diaminopropane with 2,6‐diformyl‐4‐tert.‐butylphenol in the presence of equimolar amounts of MnX2·4 H2O and Mn(OAc)2·4 H2O in methanol leads to the Mn(II),M(II) complexes (I) of the formed macrocycle.

ChemInform Abstract: Synthesis and Characterization of Ru(II) and Ru(III) Complexes of Diphenylphosphinoacetic Acid and Their Interaction with Small Molecules.

AbstractThe Ru(II) and Ru(III) complexes (I)‐(VII) are obtained by 2:1 and 3:1 molar reaction of the title ligand with RuCl2(PPh3)3 in refluxing acetone, with RuCl2(DMSO)4 in refluxing ethanol, with RuCl3(AsPh3)2 in refluxing acetone and with RuCl3·3 H2O in methanol, respectively.

ChemInform Abstract: Preparation, Characterization and Crystal Structure of a Binuclear Thorium(IV) Complex with a Pentadentate Compartmental Schiff Base.

AbstractThe pentadentate Schiff base H3L is obtained by 1:2 molar condensation of 2,6‐diformyl‐4‐chlorophenol with o‐aminophenol and reacts with Th(NO3)4·4 H2O in the presence of the stoichiometric amount of LiOH and Mg(OAc)2·4 H2O in methanol to yield the binuclear Th(IV) complex (I).

Bis(µ-diphenylphosphido-µ′-carbonyl-π-methylcyclopentadienyl-carbonyliron)-rhodium hexafluorophosphate: a non-closed trinuclear rhodium–iron complex

The reaction of [Rh(C8H12)Cl]2, [Rh(CO)2Cl]2, or RhCl3,3H2O in methanol or [Rh(C8H12)(thf)2]+ in tetrahydrofuran with an excess of [Fe(PPh2)(CO)2(π-C5H4Me)] in the presence of PF6– affords the title compound; an X-ray diffraction analysis shows the metals to be in a non-clustered configuration.