Clathrate formation in the [M(4-MePy)2 (NCS)2]-4-MePy systems,where M=Co(II), Ni(II), Zn(II), Cd(II); 4-MePy=4-methylpyridine

A number of complexes [M(4-MePy)_n (NCS)₂], where M=Co(II), Ni(II), Zn(II), Cd(II); n=2 or 4 have been synthesized and phase diagrams [M(4-MePy)₂(NCS)₂]-4-MePy have been studied. The forming compounds have been obtained and described with the help of IR-spectroscopy and thermal analysis. The structure of a molecular type with variable section channels, filled by two types guest-molecules (by a water molecule in the narrow part of the channel and by two 4-methylpyridine molecules in the broad part of the channel, with a total ratio guest: host being 1:1) for [Cd(4-MePy)₄ (NCS)₂]·0.67(4-MePy)·0.33H₂O has been defined by X-ray method. This clathrate is isostructural (X-ray powder diffractogram) to the anhydrous compound [Cd(4-MePy)₄ (NCS)₂]·0.67(4-MePy).     

Phase and structural study of clathrate formation in the [Zn(MePy)2(NCS)2]-MePy system (MePy=4-methylpyridine)

A phase diagram of the [Zn(MePy)₂(NCS)₂]-MePy binary system has been studied by DTA and solubility methods. Two compounds melting incongruently (at 63 and 57°C) have been discovered in the system. They have been obtained as separate phases with crystals of different shape (needles and octahedra). Their composition has been determined by analytical methods and verified by X-ray structural analysis: [Zn(MePy)₄(NCS)₂]·0.67 MePy·xH₂O, wherex depends on the synthesis conditions, and [Zn(MePy)₄(NCS)₂]·MePy, respectively.The preliminary X-ray study of the first compound (at –100°C) has shown it to be isostructural with the known clathrates of the common formula [M(MePy)₄(NCS)₂]·0.67MePy·xH₂O, where M=Cu, Mn, Mg andx=0–0.33. The unit cell parameters are as follows:a=27.20(1),c=11.202(4) Å, space group ,Z=9.The X-ray study of [Zn(MePy)₄(NCS)₂]·MePy (at–50°C) has shown it to be analogous to the organic zeolite -phase with the guest MePy molecules located in the channels formed by molecular packing of the [Zn(MePy)₄(NCS)₂]host. The cell is tetragonal, the space groupI4₁/a,a=16.845(6),c=23.496(7) Å,V=6667(4) ų,Z=8,D _calc=1.289 g cm^–3,R=0.074. The zinc cation is surrounded by a slightly irregular octahedron of six nitrogen atoms of the MePy and NCS ligands. The crystallisation field of the host [Zn(MePy)₄(NCS)₂] complex in the temperature range concerned is absent in the phase diagram. It suggests contact stabilization of the [Zn(MePy)₄(NCS)₂] molecule by the guest in the clathrates. Supplementary Data relevant to this paper have been deposited with the British Library at Boston Spa, Wetherby, West Yorkshire, U.K. as Supplementary Publication No. SUP 82166 (15 pages).     

Thermochemical investigation of guest-host interactions in Werner clathrates of type [Ni(4-Etpy)4(NCS)2]·nG (G=naphthalene derivatives)

The stoichiometry of thermal decomposition and the thermochemistry were studied for [NiL₄(NCS)₂] (I) as a host complex, and for its clathrates of type [NiL₄(NCS)₂]·2G, where L=4-ethylpyridine and guest molecule G=1-methylnaphthalene in clathrate (II), 1-chloronaphthalene in (III) or 1-bromonaphthalene in (IV). For I, the loss of volatile components proceeds in three steps (–2L, –L, –L); the first steps for II–IV also involve the release of G (–2G, –2L). DSC and X-ray powder measurements indicated a phase transition in the host lattice, and allowed differentiation of the escape of G and L molecules. The enthalpy changes give the following sequence of thermodynamic stability for the studied chlathrates: I>II>III.     

Peculiarities of the crystal structure and packing of the host and guest molecules in the [M(4-McPy)4(NCS)2]·0.67(4-McPy)·0.33 H2O Clathrates (M = Cu(II), Mn(II); 4-MePy = 4-Methylpyridine)

The crystal structures of the two clathrates with the composition [M(4-MePy)₄(NCS)₂]·0.67(4-McPy)·0.33 H₂O (M=Cu(II), Mn(II); 4-MePy=4-methylpyridine) have been determined. These compounds are trigonal, with the [M(4-MePy)₄(NCS)₂] host molecules being centrosymmetric. The parameters of the unit cells area = 27.365(7) and 27.738(6),c = 11.303(9) and 11.250(8) Å,V = 7325(2) and 7493(2) ų, space group R , R = 0.053 and 0.109 for M = Cu(II) and Mn(II), respectively. ForZ = 9d _calcd is equal to 1.271 and 1.225 g/cm³, andd _measd is equal to 1.252(2) and 1.213(2) g/cm³ for the Cu and Mn clathrates, respectively. The coordination environment of the metal atoms in these compounds is an irregular octahedron, while in the Mn compound these distortions are rather small (Mn-N_MePy 2.30, 2.34 Å, Mn-N_NCS 2.18 Å, and Cu-N_MePy 2.06 Å, Cu-N_NCS 1.98 Å and Cu-N_MePy 2.50 Å).The molecular packing in the structures is such that the channels of variable diameter are formed along the short cell dimension (the maximum diameter is 10 Å, the minimum being 6 Å) where the guest 4-MePy and H₂O molecules are placed.     

Vapour pressure of 4-methylpyridine (MePy) over [Ni(MePy)4(NCS)2]·y(MePy) and [Cu(MePy)4(NCS)2]·2/3(MePy) clathrates during their dissociation

Strain measurement and quasiequilibrium thermogravimetry were used to study the dissociation processes of two clathrates, [Ni(MePy)₄(NCS)₂]·(MePy) and [Cu(MePy)₄(NCS)₂]·2/3(MePy), accompanied by the liberation of MePy into the gaseous phase. In the Ni clathrate dissociation process in the temperature range 298–368 K the liberated MePy was redistributed between the solid clathrate and gaseous phases; the MePy vapour pressure over the clathrate is a function of temperature and the guest contenty, which agrees with the presence in the MePy-[Ni(MePy)₄(NCS)₂] system of a wide range of -clathrate solutions, [Ni(MePy)₄(NCS)₂]·y(MePy). The same methods used to study the Cu clathrate dissociation resulted in conclusions different from those obtained for the dissociation process of the above clathrate: the process is described by the equation [Cu(MePy)₄(NCS)₂]·2/3(MePy)_solid =[Cu(MePy)₂(NCS)₂]_solid+22/3(MePy)_gas; the temperature dependence of the Mepy vapour pressure over the solid sample does not depend on its composition, which points to the absence from the system of solid solutions based on the clathrate. Standard changes of the enthalpy, entropy, and isobaric-isothermal reaction potential for the temperature range 292–325 K are equal to 178.6±1.7 kJ (mole of clathrate)^–1, 463±5.6 J (mole of clathrate)^–1 K^–1, and 40.4±2.4 kJ (mole of clathrate)^–1, respectively.     

Studies in werner clathrates. Part 2. Structures of bis (isothiocyanato) tetra (4-phenylpyridine) nickel (II)· 4-dimethylsulphoxide,bis (isothiocyanato) tetra (3-methylpyridine) nickel (II)· chloroform and bis (isothiocyanato) tetra (3,5-dimethylpyridine) nickel (II)

The structures of Ni(NCS)₂(4-PhPy)₄·4DMSO and Ni(NCS)₂(3-MePy)₄·CHCl₃ have been elucidated. Movement of guest molecules through channels in the host structure was simulated by potential energy calculations. Ni(NCS)₂(3,5-diMePy)₄ does not form inclusion compounds. An intra-molecular potential energy study shows that theortho-hydrogens on the 3,5-dimethylpyridine ligands control the conformation of the molecule. The same result is obtained with the 4-methylpyridine ligand, which suggests that the extent of rotation of substituted pyridines about the Ni–N bounds is not a factor governing clathrate formation. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82030 (43 pages).     

Direct hydrogen-1, carbon-13, and nitrogen-15 NMR study of magnesium(II)-isothiocyanate complexing

A hydrogen-1, carbon-13, and nitrogen-15 NMR study of magnesium(II)-isothiocyanate complexation in aqueous mixtures has been completed. At temperatures low enough to slow proton and ligand exchange, separate¹H,¹³C, and¹⁵N NMR signals are observed for coordinated and bulk water molecules and anions. The¹H NMR spectra reveal signals for the hexahydrate and the mono-through triisothiocyanato complexes, as well as two small signals attributed to [Mg(H₂O)₅(OH)]¹⁺ and [Mg(H₂O)₄(OH)(NCS)]. Accurate hydration numbers were obtained from signal area integrations at each NCS^– concentration. In the¹⁵N NMR spectra, signals also were observed for the mono-through triisothiocyanato complexes, and a small signal believed to be due to [Mg(H₂O)₄(OH)(NCS)]. Coordination number contributions for NCS^– were measured from these spectra and when combined with the hydration numbers they totalled essentially six at each anion concentration. Signals for [Mg(H₂O)₅(NCS)]¹⁺ through [Mg(H₂O)₃(NCS)₃]^1– also were observed in the¹³C NMR spectra and the area evaluations were comparable to the¹⁵N NMR results. An analysis of the magnitude and sign of the coordinated NCS^– chemical shifts identified the nitrogen atom as the anion binding site. All spectra indicated [Mg(H₂O)₅(NCS)]¹⁺ and [Mg(H₂O)₄(NCS)₂] were the dominat isothiocyanato complexes over the entire range of anion concentrations. The inability to detect evidence for complexes higher than the triisothiocyanato reflects the competitive binding ability of water molecules and perhaps the decreased electrostatic interaction between NCS^– and negatively charged higher complexes.     

Cobalt(II) and nickel(II) complexes with 4-amino-6-methyl-5-oxo-3-phenylamino-1,2,4-triazine

Summary Cobalt(II) and nickel(II) complexes of 4-amino-6-methyl-5-oxo-3-phenylamino-1,2,4-triazine (ATAZ), MX₂(ATAZ)₂ · 2 H₂O (M = Co or Ni; X = Cl, Br, I or NCS), have been isolated. The electronic spectra, magnetic moments and i.r. spectra of the compounds have been studied.Pseudo-octahedral environments are proposed for the complexes: [MX₂(ATAZ)₂]. 2 H₂O (M = Ni or Co; X = Cl or Br) and [CoI₂(ATAZ)₂(H₂O)₂], and apseudo-tetrahedral structure for [NiX₂(ATAZ)₂] · 2 H₂O (X = I or NCS) and [Co(NCS)₂-(ATAZ)₂] · 2 H,O. However, [CoX₂(ATAZ)₂]. 2 H₂O (X = Cl or Br) give acetone solutions containing tetrahedral cobalt(II).     

Synthesis and Structure of Co(III) Coordination Compounds [Co(DH)2(Anil)2][BF4] and [Co(DH)2(Py)2][BF4]

The complex compounds [Co(DH)₂(Anil)₂][BF₄] and [Co(DH)₂(Py)₂][BF₄] were synthesized from Co(BF₄)₂ · 6H₂O–DH₂–A–alcohol–water systems (DH₂ is dimethylglyoxim and A is pyridine (Py) or aniline (Anil)), and their crystal structures were determined using X-ray diffraction analysis. In octahedral Co(III) complexes, two dimethylglyoxime radicals lie in the equatorial plane and are joined via the intramolecular hydrogen bond O–H···O. The complexes with pyridine and aniline have similar configurations but different crystal structures.     

Synthesis and spectroscopic, diffractometric, and magnetic analysis of lanthanide compounds with thiocyanate and hexamethylenetetramine

Summary New complex salts of lanthanide thiocyanates with hexamethylenetetramine of the general formulaLn(NCS)₃·2[N₄(CH₂)₆·nH₂O, whereLn=La,Pr,Nd,Sm,Gd,Dy,Er andn=0–10, have been analyzed. IR spectra have been obtained in the range of 200–4000 cm^–1, frequencies of vibrations of low and high hydration state compounds have been analyzed, and differences between the structures of the coordination speheres of these salts are demonstrated. Diffractometric examinations and measurements of the magnetic susceptibility of several salts have been performed.

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Synthese und spektroskopische, diffraktometrische und magnetische Untersuchungen von Verbindungen der Lanthaniden mit Rhodanid und Hexamethylentetramin

Zusammenfassung Neue Komplexsalze der Lanthaniden mit Rhodanid und Hexamethylentetramin mit der allgemeinen FormelLn(NCS)₃·2[N₄(CH₂)₆]·nH₂O (Ln=La,Pr,Nd,Sm,Gd,Dy,Er;n=0–10) wurden untersucht. Die IR-Spektren der Verbindungen im Bereich von 200–4000 cm^–1 wurden aufgenommen. Die Schwingungsfrequenzen hoch- und niederhydrierter Verbindungen wurden analysiert und die Unterschiede in der Struktur der Koordinationssphäre bestimmt. An einigen Komplexen wurden diffraktometrische Untersuchungen und Messungen der magnetischen Suzaptibilität durchgeführt.

     

Structural and magnetic studies of tetranuclear heterometallic M/Cr (M = Co,Mn) complexes self-assembled from zerovalent cobalt or manganese,Reineckes salt and diethanolamine

Four novel heterometallic complexes [Co₂Cr₂(NCS)₄(HDea)₂(Dea)₂]·4dmf (1), [Co₂Cr₂(NCS)₄(HDea)₂(Dea)₂]·4dmso (2), [Mn₂Cr₂(NCS)₄(HDea)₂(Dea)₂(dmf)₂]·2dmf (3) and [Mn₂Cr₂(NCS)₄(HDea)₂(Dea)₂(dmso)₂]·4dmso (4) have been prepared using zerovalent cobalt (1, 2) or manganese (3, 4), Reineckes salt, ammonium thiocyanate and a non-aqueous solution of diethanolamine (H₂Dea) in air. The single X-ray analysis reveals that all compounds have similar centrosymmetric crystal structures based on a tetranuclear {M₂Cr₂(μ₃-O)₂(μ-O)₄} (M = Co, Mn) core. Variable-temperature magnetic susceptibility measurements of 1, 2 and 4 show antiferromagnetic coupling between the magnetic centers, while 3 exhibits a ferromagnetic behavior.     

Two clathrates of bis(isothiocyanato)tetrakis(4-methylpyridine)magnesium(II) as a host with 4-methylpyridine as a guest

Two clathrate modifications of the title host with 4-methylpyridine (4-CH₃C₅H₄N) as a guest have been determined at –50°C. [Mg(4-CH₃C₅H₄N)₄(NCS)₂] · 2/3(4-CH₃C₅H₄N) · 1/3H₂O is trigonal, space group , witha=27.630(7),c=11.219(3) ÅV=7417(4) ų,Z=9,D _calc=1.171 g cm^–3,(CuK )=18.506 cm^–1, finalR=0.064. [Mg(4-CH₃C₅H₄N)₄(NCS)₂] · (4-CH₃C₅H₄N) is tetragonal, space group I4_l/a, witha=16.944(7),c=23.552(9)Å,V=6762(5) Å,Z=8,D _calc=1.191 g cm^–3, (CuK )=18.200 cm^–1, finalR=0.071.The structures consist of molecular packings of the same host complex units and the guest species. The Mg(II) cation is octahedrally coordinated to theN-atoms of four 4-methylpyridine and twotrans-coordinated isothiocyanato ligands in the host molecule. The conformations of the molecule are considerably different both in symmetry and in geometry in these two structures. The guest 4-methylpyridine molecules are disordered into channels which have different topology in these two clathrates resulting in different thermal stability.     

Synthesis,protonation and substitution behaviour of K3[ReO2(CN)4]

Summary The preparation and characterization of salts of the [ReO₂(CN)₄]^3–, [ReO(OH)(CN)₄]^2–, [ReO(H₂O)(CN)₄]^–, [Re₂O₃(CN)₈]^4– and [ReO(NCS)(CN)₄]^2– species are described. The nature of the protonation reactions of [ReO₂(CN)₄]^3– was established by the successful isolation of these salts.     

Synthesis,spectroscopic, thermal,crystal structure properties and characterization of new Hofmann-type-like clathrates with 4-aminopyridine and water

In this study, synthesis of two new heteronuclear tetracyanonickelate(II) clathrates based on 4-aminopyridine (4AP) and guest water (H₂O) molecule and investigation of their structural properties were reported. These clathrates were characterized by using vibration spectroscopy, elemental, thermal analysis and single crystal X-ray diffraction (SC-XRD) techniques. Examining the elemental and spectral data of these clathrates, it was observed that the formulas [Zn(II)(4AP)₂Ni(µ-CN)₂(CN)₂]·6H₂O and [Cu(II)(4AP)₄Ni(µ-CN)₂(CN)₂]·H₂O were defined their structures. General information about the structural properties of these clathrates in single crystal form has been obtained by considering the changes in the characteristic peaks of the cyanide group and the 4AP that formed them. The thermal behaviors of these clathrates were obtained by examining the temperature-dependent changes of their masses. The magnetic susceptibilities of these clathrates in single crystal form were measured with a Gouy balance. According to the data obtained using SC-XRD technique, the heterometallic [Zn(II)(4AP)₂Ni(µ-CN)₂(CN)₂]·6H₂O compound has Cmcm and the heterometallic [Cu(II)(4AP)₄Ni(µ-CN)₂(CN)₂]·H₂O compound has crystal structures in the C2 / c space group.     

Kobalt(III) ammin-derivate einiger Reineckesalz-Analoga mit Toluidinen

Zusammenfassung Es wurden 39 neue Komplexsalze durch doppelte Umsetzung aus wäßrig-alkohol. Lösungen der folgenden Reineckeat-Analoga: [Cr(NCS)₄(o-Toluidin)₂]^–, [Cr(NCS)₄(m-Toluidin)₂]^– und [Cr(NCS)₄(p-Toluidin)₂]^– und Hexammin-, Monoacido-pentammin-und Diacido-tetrammin-kobalt(III)-komplexsalze erhalten.Es wurden in einigen Fällen Abweichungen in physikochemischen Eigenschaften, wie Farbtönung, Kristallform, Löslichkeit und papierchromatographischeR _F-Werte, bei den stellungsisomeren Salzen vom Typus: Kation·[Cr(NCS)₄(Toluidin)₂] und auch bei den Koordinationsisomerpaaren: [Co(DH)₂(o-Toluidin)₂][Cr(NCS)₄(p-Toluidin)₂] und [Co(DH)₂(p-Toluidin)₂] [Cr(NCS)₄(o-Toluidin)₂], usw. beobachtet.

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Cobalt(III) ammine derivatives of some reineckate analogues with toluidines

39 new complex salts were prepared by double conversion of the reineckate analogues [Cr(SCN)₄(o-toluidine)₂]^–, [Cr(SCN)₄(m-toluidine)₂]^–, and [Cr(SCN)₄(p-toluidine)₂]^– with the hexammine, monoacido-pentammine and diacido-tetrammine complexes of Co(III). In some of the position and coordination isomers deviations from the standard physico-chemical properties, i.e. color, crystal form, solubility and paper chromatographyR _f-values were observed.

     

Kobalt(III)ammin-derivate einiger Reineckesalz-Analoga mit Xylidinen

Zusammenfassung Es wurden 34 neue Komplexsalze durch doppelte Umsetzung aus wäßr.-alkohol. Lösungen der folgenden Reineckeat-Analoga: [Cr(NCS)₄(m-xylidin)₂]^–, [Cr(NCS)₄(p-xyl)₂]^– und Hexammin-, Monoacido-pentammin- und Diacido-tetramminkobalt(III)-komplexsalze erhalten. Es wurden in einigen Fällen Unterschiede in physiko-chemischen Eigenschaften, wie Farbtönung, Kristallform, Löslichkeit und papierchromatographischeR _f-Werte, bei den stellungsisomeren Salzen vom Typus: Kation · [Cr(NCS)₄(xyl)₂] und auch bei den Koordinationsisomerpaaren: [Co(DH)₂(m-xyl)₂] [Cr(NCS)₄(p-xyl)₂] und [Co(DH)₂(p-xyl)₂] [Cr(NCS)₄(m-xyl)₂] usw. beobachtet.

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Cobalt(III)ammine derivatives of some reineckate analogues with xylidines

34 new complex salts were prepared by double conversion of the reineckate analogues [Cr(NCS)₄(m-xylidine)₂]^–, [Cr(NCS)₄(p-xyl)₂]^–, with the hexammine-, monoacido-pentammine- and diacidotetrammine-complexes of Co(III). In some of the position and coordination isomeres differences of the standard physico-chemical properties, i.e. color, crystal form, solubility and paper chromatographyR _f-values were observed.

     

Processes of Thermal Dissociation of Clathrates on the Base of Coordination Compounds

Inclusion compounds are very interesting materials for thermoanalytical investigations. Stable guest molecules are packed in the cages, channels or layers in the host matrix, thermal dissociation reactions are reversible and have the clear-cut stoichiometry. The clathrates with a matrix of coordination compounds (of the type [MA₄X₂]·nA) were synthesized (M=transition metals; A=Py, 4-MePy; X=NO₃, NCS, NCO; n=0.67 or 1 or 2). Four Py or MePy molecules are tightly bound in the coordination sphere by M-N bonds and others are confined in the matrix cavities by van der Waals forces. Processes of thermal dissociation of the clathrates were studied. Q-thermogravimetry (for checking the stable intermediate phases) and the home-made gas-flow reactor (as EGA-device for kinetic studies) were used. The compensation dependence (lgA_i=aE_i+b) was observed for the most of clathrates series, it was explained by the identity of the reaction mechanism. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis and characterisation of cobalt(III) complexes with 1,1-dimethylethylenediamine (1,1-dmen) and 1,2-propanediamine (pn)

Two stable diamine complexes [Co(1,1-dmen)₂(NCS)₂]SCN · (H₂O)_1.5 (1) and [Co(pn)₂(NCS)₂]SCN · (H₂O)_1.5 (2) have been synthesised and characterised by elemental analysis, i.r. and electronic spectra and t.g.a. The structure of (1) has been confirmed by single-crystal X-ray diffraction and reveals that the cobalt complex has octahedral geometry and consists of two crystallographically independent cations, both situated on centres of inversion. In the crystal structure of (1), free H₂O molecules and SCN^– ions form an extensive hydrogen bonding network with the cation. It is an ordered pseudo-polymorph of a previous structure determination. Both (1) and (2) are diamagnetic.     

Rhenium. Part XIX. A new isothiocyanato complex of quadrivalent rhenium

Summary Reaction between K₂[ReI₆] and KSCN in boiling MeOH or in the melt gave [Re(NCS)₆]^2– and a weakly paramagnetic species, isolated as its Cs salt. Tl, Me₄N and other salts of this species have been isolated from the reaction medium of from the Cs salt by metathesis. On the basis of magnetic susceptibility and i.r. spectra the new complex has been formulated as [Re₂(NCS)₁₂]^4– containing metalmetal bond and no bridging thiocyanate. The Me₄N salt has also been isolated by bioling aqueous solutions of HReO₄ and HSCN and then adding Me₄NCL. A pyridinium salt, formulated as (pyH)₄[Re₂(NCS)₁₂], has been obtained by boiling [ReO₂py₄]NCS with aqueous HSCN. The two complex species [Re(NCS)₆]^2– and [Re₂(NCS)₁₂]^4– show distinctly different magnetic moment and electronic spectra.     

Thermal and photochemical interaction of octacyanometallates(IV), [M(CN)8]4− (M = Mo or W) in the presence of pyrazine

The interactions between [M(CN)₈]^4– (M = Mo or W) and pyrazine (pz) in the solid state and in aqueous solutions have been analysed. In strongly acidic solutions {pzH⁺, [M(CN)₈]^4–} ion pair formation is observed; the pyrazinium salts (pzH)₂(H₃O)₂[Mo(CN)₈]·0.5pz·3H₂O and (pzH)₂K(H₃O)[W(CN)₈]·H₂O have been isolated. The X-ray crystal structure of the latter, and the spectroscopic properties of both, are described. The [W(CN)₈]^4– anion is approximately square antiprismatic (D_4d), with different H-bond environments around the N atoms. The ligand-field photolysis of [M(CN)₈]^4– in the presence of pyrazine in neutral and alkaline solution results in the formation of tetracyanooxometallates(IV) in equilibrium with pentacyanooxometallates(IV) through the [M(CN)₇(pz)]^3– anions as intermediates. The formation of the [M(CN)₆(pz)₂]^2– ion, postulated in the literature to be the final product of the alkaline photolysis, has definitively been excluded.