Phenol as a guest molecule in clathrate compounds

Phenol, having favourable physical and chemical properties, can be enclosed as the guest component in the clathrates of tetracyano complexes. Six compounds of Hofmann and similar type clathrates M(NH₃)₂M' (CN)₄.nG and M(en)_m M'(CN)₄.nG were prepared and identified: Ni(NH₃)₂Pt.2C₆H₅OH; Ni(en)₂Pt(CN)₄.O.14C₆H₅OH; Ni(NH₃)₂Pt(CN)₄.C₆H₅OH.H₂O; Zn(NH₃)₂Ni(CN)₄.O.1C₆H₅OH.H₂O; Cu(NH₃)₂Ni(CN)₄. 2C₆H₅OH and Fe(NH₃)₂Ni(CN)₄.2C₆H₅OH. The phenol containing clathrates are more stable than clathrates containing other guest molecules. In the case of Ni(en)₂ Pt(CN)₄.O.14C₆H₅OH thermal loss of the guest molecule leaves the host lattice intact, but further heating results in the rupture of the host lattice. The compounds were capable in the solid state of sorbing other organic molecules once they had been heated to the temperature required for almost complete loss of guest molecule i.e. n→o.     

An infrared spectroscopic study of dianiline-metal(ii) tetracyanometalate complexes

The results of an IR spectroscopie study are presented for six new dianiline metal tetracyanometalate complexes, M(an)₂M'(CN)₄ (M = Mn, Fe, Co or Cu and M'= Ni; M = Ni or Cd and M' = Pt; an = aniline). Their structure consists of polymeric layers of (M-M'(CN)₄)∞ with the aniline molecules bound directly to metal (M). For these series of isomorphous complexes there is a correlation between the shifts of some aniline bands on coordination and the strength of metal-nitrogen bonding measured by the v(M-N) value. Low temperature (83 K) data are also reported and it is noted that whilst the aniline ring and CH mode frequencies are virtually insensitive to temperature, the NH₂ wagging, NH₂ rocking and the metal-ligand stretching v(M-N) frequencies increase with decreasing temperature, whilst the v(NH₂) modes decrease with decreasing temperature. The vibrational frequencies of the M'(CN)₄ group are also temperature dependent and increase in value upon cooling the sample to 83 K. The changes are thought to be due to a slight contraction in the cavity size with decreasing temperature. The relationship between these complexes and Hofmann-type aniline clathrates, M(NH₃)₂M'(CN)₄ · 2 an, is indicated.     

Recent developments in the chemistry of hofmann-type and the analogous clathrates

Based on the structural features of Hofmann-type clathraces M(NH₃)₂M'(CN)₄ · 2G (M = a divalent metal in six-coordination, M' = a divalent metal in square-planar coordination, G = a small aromatic guest molecule), several series of the analogous clathrates have been derived by appropriate replacements of the host moieties. These clathrates are designated with a general formula Cd (diam)M'(CN)₄ ·$\text{n}$G where diam refers to diammine, an ambident diamine or monoethanolamine (mea), or a pair of unidencate mea's, M'(CN)₄ is a square-planar or a tetrahedral tetracyanometallate(II), and G is a small aromatic guest molecule. The number of guest molecules, $\text{n}$, varies stepwise from 2 through $\text{3}\text{2}$ to 1 depending on the bulkiness of diam ligand which builds up the host structure. Their structural features are discussed on the two- and three-dimensional networks of the metal complex hosts. The historical background is also reviewed briefly.     

The crystal structures of α,ω-diaminoalkanecadmium(II) tetracyanonickelate(II)-aromatic molecule inclusion compounds. I. 1,4-diaminobutanecadmium(II) tetracyanonickelate(II)-2,5-xylidine (1/1): Cd(NH2(CH2)4NH2)Ni(CN)4. (CH3)2C6H3NH2

The title compound crystallizes in monoclinic space group P2₁/m with a=9.795(2), b=15.010(2), c=7.125(1) Å, =105.56(1)^o, and Z=2. The structure has been refined to the weighted Rw=0.042 for 2742 reflections collected by counter method. Two-dimensionally extended but wavy cyanometal complex layers are bridged by 1,4-diaminobutane (dabn) to give a three-dimensional host structure which provides a channel-like cavity with the guest 2,5-xylidine molecule. The skeleton of the bridging dabn takes a trans-cis conformation to make the packing efficient between the cavity and the guest molecule. The series of Hofmann-dabn-type Cd(NH₂ (CH₂)₄NH₂) Ni (CN)₄. nG inclusion compounds are described for several aromatic guest molecules G with various stoichiometric coefficients n. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82020 (22 pages).     

Vibrational spectroscopic and thermal studies of some 3-phenylpropylamine complexes

Four new Hofmann–3-phenylpropylamine (3PPA) type complexes with chemical formulae M(3PPA)₂Ni(CN)₄ (M = Ni, Co, Cd, and Pd) have been prepared and their vibrational spectra are reported in the region of 4000–60 cm⁻¹. The vibrational bands arising from 3PPA ligand molecule, the polymeric sheet and metal–ligand bands of the compounds are assigned. The thermal behaviour of these complexes is also provided using the DTA and TGA along with the magnetic susceptibility data. The results indicate that the monodentate 3PPA ligand molecule bonds to the metal atom of |M–Ni(CN)₄|_∞ polymeric layers and hence the compounds are similar in structure to Hofmann-type complexes.     

Dinuclear complexes with a μ-cyano ligand. Part XI(1). Synthesis and characterization of several derivatives ofcis-[Co(NH3)(en)2(H2O)]3+

Summary The new complex double saltscw-[Co(NH₃)(en)₂(H₂O)]₂ [M(CN)₄]₃ (en = ethylenediamine; M = Ni, Pd or Pt),cis-[Co(NH₃(en)₂(H₂O)]₂[FeNO(CN)₅]₃ andcis-[Co(NH₃)(en)₂(H₂O)][Co(CN)₆] have been synthesized and by anation in the solid state the corresponding new dinuclear complexes with a cyano bridgecis- ortrans-[(NH₃)(en)₂Co-NC-M(CN)₃]₂ [M(CN)₄] (M = Ni, Pd or Pt);cis-, trans-[(NH₃)(en)₂Co-NC-FeNO(CN)₄]₂[FeNO(CN)₅] andcis-[(NH₃)(en)₂Co-NC-Co(CN)₅ have been prepared. The complexes have been characterized by chemical analysis, t.g. measurements, and by i.r. and electronic spectroscopy. With [Ni(CN)₄][^2– and [Co(CN)in]₆ ^3– only thecis-isomer is produced; with [Pd(CN)₄]^2–, [Pt(CN)₄]^2– and [FeNO(CN)₅]^2– thetrans- isomer is the dominant species. The dinuclear complex derived from [Pt(CN)₄]^2– shows strong Pt-Pt interactions both in the solid state and in solution.     

A perchlorate-promoted electrochemically induced nitride coupling reaction

The osmium nitride complex [Os^VI(NH₃)₄N]³⁺ undergoes a one-electron reduction in acetonitrile to give [Os^V(N)(NH₃)₄]²⁺, which further reacts by nitride coupling to give the μ-dinitrogen osmium complex [(CH₃CN)(NH₃)₄Os^II(N₂)Os^II(NH₃)₄(CH₃CN)]⁴⁺. The formation of the μ-dinitrogen osmium complex is promoted by the presence of perchlorate anion, which causes the deposition of [(CH₃CN)(NH₃)₄Os^II(N₂)Os^II(NH₃)₄(CH₃CN)](ClO₄)₄ on the electrode surface upon repetitive voltammetric scans.     

Reactions of the carbonyl complexes M(CO)3(L)3 (L = py,M = Mo,W; L = NH3, M = Mo) and M(CO)4(2-Mepy)2 (M = Mo,W) with HgX2 (X = Cl,CN, SCN)

The reactions of the substituted Group VI metal carbonyls of the type M(CO)₄(2-Mepy)₂ (M = Mo, w) and M(CO)₃(L)₃ (L = py, M = Mo, W; L = NH₃, M = Mo) with mercuric derivatives HgX₂ (X = Cl, CN, SCN) have given rise to three series of tricarbonyl complexes: M(CO)₃(py)HgCl₂ · 1/2HgCl₂ (M = Mo, W); 2[M(CO)₃(L)]Hg(CN)·nHg(CN)_x (L = py, M = Mo, W, n = $\text{1}\text{2}$, × = 2; L = 2- Mepy, × = 1; M = Mo, n = 3; M = W, n = 1); and [M(CO)₃(L)Hg(SCN)₂ · nHg(SCN)₂] (L = py, M = Mo,W, n = 0; L = 2-Mepy, M = Mo, W, n = $\text{1}\text{2}$; L = NH₃, M = Mo, n = 0) depending on which mercuric compound is employed. All the reactions with Hg(SCN)₂ give isolable products whereas those with Hg(CN)₂ and HgCl₂ did so far only the reactions with [M(CO)₄(2-Mepy)₂] and M(CO)₃(py)₃. The greater reactivity of Hg(SCN)₂ than of Hg(CN)₂ and HgCl₂ is consistent with the various acceptor capacities of the groups bonded to the mercury atom.The reactions studied always involve displacement of the N-donor ligand of the original complex and partial or total displacement of the halide or pseudohalide groups of the mercury compound to give in all cases compounds containing MHg bonds. In addition, elimination of a CO group in the tetracarbonyl complexes M(CO)₄(2-Mepy)₂occurs.     

Some less usual properties of tetracyano complexes

The structure and reactivity of one unique molecule may be understood only in relation to its molecular surroundings. The non-stoichiometric forms of the tetracyano complexes M(B) _mM (CN)₄·nG (B=nitrogen or oxygen containing base; G=aromatic compound or H₂O,m0,n>0) are understood in this respect. Their stoichiometric or non-stoichiometric forms, with voids either completely or more often partially occupied, are responsible for their observed sorptive and resorptive abilities. The effects of the surroundings are correlated with the results of thermal analysis, magnetic measurements and their sorptive abilities.Dedicated to Professor H. M. Powell.     

Die Kristallstrukturen von (NH4)2[ReCl6], [ReCl2(CH3CN)4]2[ReCl6] · 2CH3CN und [ReCl4(18-Krone-6)]

The Crystal Structures of (NH₄)₂[ReCl₆], [ReCl₂(CH₃CN)₄]₂[ReCl₆] · 2CH₃CN and [ReCl₄(18)(Crown-6)] Brown single crystals of (NH₄)₂[ReCl₆] are formed by the reaction of NH₄Cl with ReCl₅ in a suspension of diethylether. [ReCl₂(CH₃CN)₄]₂[ReCl₆] · 2CH₃CN crystallizes as brown crystal plates from a solution of ReCl₅ in acetonitrile. Lustrous green single crystals of [ReCl₄(18-crown-6)] are obtained by the reaction of 18-crown-6 with ReCl₅ in a dichloromethane suspension. All rhenium compounds are characterized by IR spectroscopy and by crystal structure determinations. (NH₄)₂[ReCl₆]: Space group Fm3 m, Z = 4, 75 observed unique reflections, R = 0.01. Lattice constant at ?70°C: a = 989.0(1) pm. The compound crystallizes in the (NH₄)₂[PtCl₆] type, the Re? Cl distance is 235.5(1) pm. [ReCl₂(CH₃CN)₄]₂[ReCl₆] · 2CH₃CN: Space group P1, Z = 1, 2459 observed unique reflections, R = 0.12. Lattice dimensions at ?60°C: a = 859.0(1), b = 974.2(7), c = 1287.3(7) pm, α = 102.69(5)°, b? = 105.24(7)°, γ = 102.25(8)°. The structure consists of two symmetry-independent [ReCl₂(CH₃CN)₄]⁺ ions with trans chlorine atoms, [ReCl₆]^2? ions, and included acetonitrile molecules. In the cations the Re? Cl bond lengths are 233 pm in average, in the anion they are 235 pm in average. [ReCl₄(18-crown-6)]: Space group P2₁/n, Z = 4, 3 633 observed unique reflections, R = 0.06. Lattice dimensions at ?70°C: a = 1040.2(4), b = 1794.7(5), c = 1090.0(5) pm, b? = 108.91(4)°. The compound forms a molecular structure, in which the rhenium atom is octahedrally coordinated by the four chlorine atoms and by two oxygen atoms of the crown ether molecule.     

Clathrate and inclusion compounds: Part V. An infrared and Raman study of the decomposition of the Hofmann aniline clathrates M(NH3)2Ni(CN)4.2C6H5NH2 {M = Cd(II) and Ni(II)}

The time-dependent changes which are observed in the infrared and Raman spectra of samples of the two Hofmann aniline clathrates M(NH₃)₂Ni(CN)₄.an₂ {M = Cd(II), Ni(II), an = C₆H₅NH₂} indicate the occurrence of a solid state ligand replacement reaction in which the aniline guest molecule replaces the coordinated ammonia to give Man₂Ni(CN)₄ as the final product. The rate of replacement is greater for the cadmium than for the nickel clathrate, and for both clathrates evacuation of the sample greatly increases the rate of replacement. The Man₂Ni(CN)₄ complexes can themselves act as host lattices forming clathrates containing guest molecules such as aniline.     

cis-Tricyanotriamminkobalt(III)

The preparation and properties of cis-[Co(CN)₃(NH₃)₃] are described. The vibrational, ultraviolet and visible spectra have been measured. The structure of the compound has been determined by X-ray methods. By thermal decomposition of the compound, Co₂(CN)₅NH₂ and Co₂(CN)₅ have been obtained. Supercomplexes are formed with Ag⁺ and Hg²⁺ ions.     

Crystal structure of a tetrahedral cluster complex [Zn2(NH3)6(μ-OH)][Zn(NH3)4]0.5[Re4Te4(CN)12]·5H2O

A cluster complex of the composition [Zn₂(NH₃)₆(μ-OH)][Zn(NH₃)₄]_0.5[Re₄Te₄(CN)₁₂]·5H₂O is obtained by the interaction of an aqueous solution of K₄[Re₄Te₄(CN)₁₂]·5H₂O with an aqueous ammonia solution of ZnCl₂. The compound crystallizes in the C2/m (12) monoclinic space group with unit cell parameters a = 23.233(2) ?, b = 14.5906(16) ?, c = 14.3825(15) ?, β = 125.169(1)°, V = 3985.5(7) ?³, Z = 4, d _x = 3.290 g/cm³. The structure is built from cluster [Re₄Te₄(CN)₁₂]⁴⁻ anions and complex [Zn₂(NH₃)₆(μ-OH)]³⁺ and [Zn(NH₃)₄]²⁺ cations; the latter is disordered over two positions.     

Molecular dynamics study on lattice defects and heat capacity of LiCr1/6Mn11/6O4-d

Heat capacity of spinel LiCr_1/6Mn_11/6O_4-d (d=0, 0.0184)was measured between 5 and 300 K. Both compounds showed no anomaly in the measured temperature range, especially around the room temperature where a structural phase transition is reported for the parent compound LiMn₂O₄. The non-stoichiometric compound LiCr_1/6Mn_11/6O_3.9816 has greater heat capacity than that of the stoichiometric LiCr_1/6Mn_11/6O₄. Molecular dynamics study on the vibrational property of LiMn₂O_4-d revealed that the lattice defects in the non-stoichiometric compound increase the low frequency phonons compared with the stoichiometric compound. It should be related to the greater heat capacity of the non-stoichiometric compound LiCr_1/6Mn_11/6O_3.9816. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis,structure and magnetic properties of the pentanuclear complex [Fe<Subscript>2</Subscript>(CN)<Subscript>12</Subscript>Ni<Subscript>3</Subscript>(L)<Subscript>6</Subscript>]·27H<Subscript>2</Subscript>O,where L is nitronyl nitroxide

We succeeded in synthesizing a new high-spin complex [Fe₂(CN)₁₂Ni₃(L)₆]·27H₂O, where L is stable nitroxide 2-(imidazol-4-yl)-4,4,5,5-tetramethyl-2-imidazoline-3-oxide-1-oxyl. According to X-ray diffraction data, the metal core of the pentanuclear [Fe₂(CN)₁₂Ni₃(L)₆] molecule is a trigonal bipyramid with Fe atoms occupying the axial positions and linked via CN bridges to {NiL₂} fragments laying in the equatorial plane. A peculiarity of this coordination compound is a large number of water molecules per the [Fe₂(CN)₁₂Ni₃(L)₆] pentanuclear molecule in the structure. The complex character of the μ_eff(T) dependence points to many competing channels of exchange interactions between the three types of paramagnetic centers.     

New coordination cyano-bridged polymers based on tetranuclear rhenium chalcocyanide clusters and copper(ii) ammonia complexes

The reactions of aqueous solutions of the tetranuclear chalcocyanide cluster anions [Re₄Q₄(CN)₁₂]^4–, where Q = S, Se, or Te, with an ammonia solution of copper(ii) chloride at room temperature afforded a series of polymeric cyano-bridged compounds [{Cu(NH₃)₃}₂{Re₄Q₄(CN)₁₂}]·nH₂O (Q = S (1), Se (2)) and [{Cu(NH₃)₃}_1.7{Cu(NH₃)₄}_0.3Re₄Te₄(CN)₁₂] (3) having chain structures. The structures of the compounds were established by X-ray diffraction analysis. Compounds 1 and 2 are isostructural and have ordered structures. In structurally similar compound 3, the copper atoms are disordered over two positions in such a way that the structure contains the bridging {Cu(NH₃)₃} fragments along with the terminal {Cu(NH₃)₄} fragments.     

Ionic coordination complexes based on [Re6S8(CN)4L2]n– (L = OH–, NH3; n = 2, 3) cluster anions,and Ni(II) and Cd(II) ammine cations

Two new complexes containing M(II) ammine cations (M = Ni, Cd) and octahedral rhenium(III) thiocyanoammine and thiocyanohydroxoammine cluster anions, [Ni(NH₃)₆][Re₆S₈(CN)₄(NH₃)₂]?2H₂O (1) and [Cd(NH₃)₆][{Cd(NH₃)₅}{Re₆S₈(CN)₄(OH)(NH₃)}]₂?5H₂O (2), have been synthesized by hydrothermal reactions starting from Cs_1.83K_2.17[Re₆S₈(CN)₄(OH)₂]?2H₂O. The compounds were structurally characterized by single-crystal X-ray diffraction analysis, elemental analysis, energy dispersive spectroscopy, and IR spectroscopy. Both compounds adopt monoclinic crystal structures composed from discrete ionic species which are held together by multiple hydrogen bonds between CN^–, OH^–, and NH₃ ligands and lattice water. 2 consists of {Cd(NH₃)₅}²⁺ attached to the OH group of the [Re₆S₈(CN)₄(OH)(NH₃)]^3– cluster anion via the Re–OH–Cd linkage.     

Theoretical study of the electronic spectra of bi‐ and tri‐heteronuclear platinum complexes

The electronic structure and the spectroscopic properties of [Pt(NH₃)₄][Au(CN)₂]₂, [Pt(NH₃)₄][Ag(CN)₂]₂, [Pt(CNCH₃)₄][Pt(CN)₄], and [Pt(CNCH₃)₄][Pd(CN)₄] were studied at the HF, MP2, B3LYP, and PBE levels. In all the complexes, it was found that the nature of the intermetal interactions is consistent with the presence of a high‐ionic contribution (90%) and a dispersion‐type interaction (10%). The absorption spectra of these complexes were calculated by the single‐excitation time‐dependent (TD) method at the HF, B3LYP, and PBE levels. The [Pt(NH₃)₄][M(CN)₂]₂ (M ? Au, Ag) complexes showed a ¹(dσ* → pσ) transition associated with a metal–metal charge transfer. On the other hand, the [Pt(CNCH₃)₄][M(CN)₄] (M ? Pt, Pd) complexes showed a ¹(dσ* → π*) transition associated with a metal‐to‐metal and ligand charge transfer. The values obtained theoretically are in agreement with the experimental range. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

Influence of the chloride counterion on the redox reactivity of tetraammineplatinum(II) cation with octacyanotungstate(V) anion: Crystal structure of [Pt(NH3)4]2[W(CN)8]

The redox reaction between [Pt(NH₃)₄]²⁺ and [W(CN)₈]³⁻ in the presence of Cl⁻ anions in aqueous solution affords single crystals of [Pt^II(NH₃)₄]₂[W^IV(CN)₈] and [Pt^IV(NH₃)₄Cl₂]Cl₂. Trapped cyano ligands of [W(CN)₈]⁴⁻ rectangular antiprisms of D₂ point symmetry between parallel Pt(II) square planes show that the inner-sphere redox pathway is prohibited. The presence of Cl⁻ counterions enables the formation of [Pt(NH₃)₄Cl₂]Cl₂ as the product of the rare outer-sphere pathway of the oxidation of Pt(II) by [W(CN)₈]³⁻.     

Zinc Tetracyanoplatinate: A Reversible Luminescence-Based Ammonia Sensor

ZnPt(CN)₄ was shown to be an effective material for ammonia sensing, and can be synthesized using either solution or mechanochemical methods. A combination of luminescence and Raman spectroscopy revealed that multiple species are involved in the reaction between ammonia and ZnPt(CN)₄. The crystal structure of one of these species, Zn(NH₃)₂Zn(NH₃)₃(Pt(CN)₄)₂, was elucidated. Detection of ammonia vapor down to 50 ppm in air was accomplished by monitoring the luminescence spectrum. The reaction between ZnPt(CN)₄ and ammonia vapor is reversible, and can be cycled multiple times by either flowing air over the material or heating. ZnPt(CN)₄ also has a relatively high thermal stability, decomposing only when heated above 420 °C.