Oxidation-reduction potentials of the electron acceptors in laccases and stellacyanin.

K4W(CN)8 · 2 H2O was prepared by the reduction of WO (in potassium cyanide medium) by KBH4. The reduction proceeds on the slow, drop-by-drop addition of concentrated acetic acid. The synthesis is simple and efficient because the reduction and complexation are accomplished at the same time.



Darstellung von K4W(CN)8 · 2 H2O



K4W(CN)8 · 2 H2O ist hergestellt worden durch Reduktion von WO mit KBH4 in Gegenwart von KCN. Die Reduktion findet wahrend langsamer Zugabe von Essigsaure statt. Reduktion und Komplexbildung finden gleichzeitig statt, daher wird eine gute Ausbeute erhalten.

The preparation of potassium octacyanotungstate(IV) dihydrate

The recent discovery of enzymes containing tungsten has created a new imperative for examination of key features of the structure and reactivity of biologically related compounds of this element and their relation to the corresponding properties of analogous molybdenum complexes. We have examined the relative rates of oxygen atom (oxo) transfer to substrate in the second-order reactions [MO2(mnt)2]2- + (RO)3-nR‘nP → [MO(mnt)2]2- + (RO)3-nR‘nPO in DMF solution (M = Mo, W; n = 0, R = Me; n = 1, R = Me, R‘ = Ph; n = 1, R = Et, R‘ = Me). At all temperatures examined, kMo > kW; at 298 K, kMo/kW ≈ 102−103. For (MeO)2PhP as substrate, the activation parameters for M = Mo/W are ΔH⧧ = 8.2/11 kcal/mol and ΔS⧧ = −33/−38 eu. For (MeO)3P, the values are ΔH⧧ = 10/14 kcal/mol and ΔS⧧ = −32/−33 eu. The rate differences arise primarily because of the activation enthalpy differences ΔH⧧W − ΔH⧧Mo ≈3−4 kcal/mol. Using a recent theoretical treatment of molybdenum-mediated oxo transfer to substrate (Pietsch, M. A.; Hall, M. B....

Comparative Kinetics of Oxo Transfer to Substrate Mediated by Bis(dithiolene)dioxomolybdenum and -tungsten Complexes

https://escholarship.org/content/qt0bp5b6sc/qt0bp5b6sc.pdf?t=p0jv7s

The rapid component of electron paramagnetic resonance signal II: a candidate for the physiological donor to photosystem II in spinach chloroplasts.

Publisher Summary This chapter provides a critical review of the preparation, characterization (which is often incomplete), and properties of cyanide complexes of the transition metals. It focuses on structural, thermodynamic, and kinetic data. Two prominent features of transition metal cyanide chemistry are the wide range of metal:ligand ratios in complexes and the existence of many metals in low oxidation states. The chapter discusses the bearing of the physical state of metal cyanides on structural investigations. There are two important consequences of the fact that cyanide is an ion and not a neutral molecule: metal cyanides and their complexes are nonvolatile salts rather than volatile molecular entities and much of their chemistry is concerned with processes and measurements in solution in solvents of high complexing power, so that differences in complexing by solvent and ligand are involved. The chapter considers the effect of cyanide on the stabilities with respect to oxidation and reduction of metal ions in aqueous media, taking Fe(II) and Fe(III) as an example.

Transition Metal Cyanides and Their Complexes

1. Es wurden K4[W(CN)8], 2H2O und K3[W(CN)8], H2O rein dargestellt und deren magnetische Suszeptibilitaten gemessen. Dabei wurden die folgenden Werte gefunden: 






.



Wie erwartet fur die d4sp3-Bindung der 8 CN−Liganden, erwies sich K4[W(CN)8], 2H2O als diamagnetisch und K3[W(CN)8], H2O als paramagnetisch mit einer Suszeptibilitat entsprechend einem unpaaren Elektron.

Halfdan Baadsgaard

Papers

Zur Kenntnis der komplexen Wolframcyanide K4[W(CN)8], 2H2O und K3[W(CN)8], H2O