New applications of ruthenium solar cell sensitizers N3 and N719 as luminescence turn-on anion sensors

Optical sensing of F⁻, Cl⁻, Br⁻, I⁻, OAc⁻, , , and by cis-dithiocyanatobis(2,2′-bipyridyl-4,4′-dicarboxylic acid)ruthenium(II) (N3) and bis(tetrabutylammonium) cis-dithiocyanatobis(2,2′-bipyridine-4-COOH,4′-COO⁻)ruthenium(II) (N719) have been investigated in dimethyl sulfoxide (DMSO), by means of UV-Vis absorption and emission spectrophotometric titrations. Additions of F⁻, OAc⁻, and in DMSO solution caused obvious UV-Vis spectral changes with appearance of several isosbestic points, and remarkable emission enhancements along with large blue shifts in emission bands. The values of F⁻-induced emission intensity enhancement factor (emission quantum yield enhancement factor), I/I₀ (φ/φ₀), were found to be 40 (86) and 38 (58) for N3 and N719, respectively. No obvious spectral changes were observed upon addition of Cl⁻, Br⁻, I⁻, and in DMSO solutions. Luminescent F⁻ sensing in DMSO/H₂O (4:1, v/v) has also been demonstrated to be operative with a luminescence enhancement factor of 12, indicating that N3 is very potential for practical application as fluorescent anion sensor in aqueous solution. An interaction mechanism of anion-induced deprotonation of N3 and N719 was confirmed, and the deprotonation reaction equilibrium constants of N3 and N719 were derived as well.     

Reductive thiocyanolysis of tetraoxorhenate (VII): Synthesis, crystal structure, catalytic oxidation and kinetic studies of (PPh4)2[Re(NCS)6] and (PPh4)2[ReO(NCS)5]

Thiocyanate ions reduce perrhenate in aqueous acidic solution, and on addition of a suitable countercation (PPh₄Cl) afford (PPh₄)₂[Re(NCS)₆] (1) and (PPh₄)₂[ReO(NCS)₅] (2), which have been confirmed by X-ray crystallography. The kinetics of the above reaction has been studied. Both the complexes exhibit efficient and highly selective catalytic epoxidation ability in the presence of NaHCO₃ as a co-catalyst and competent catalytic properties in the selective oxidation of alcohols to the corresponding aldehydes or ketones in the presence of pyrazole as an additive and sulfides to sulfoxides and sulfones. H₂O₂ was used as the terminal oxidant in all the above-mentioned oxidation reactions.     

Unusual kinetic and thermodynamic control in the formation of Pt(II)-complexes of a new C1-symmetric phosphine-phosphite

Versatile synthetic routes have been applied to prepare the new asymmetric phosphine-phosphite ligands 8 and 12. The chiral ligands have been designed so that the corresponding ligating groups have similar electronic properties and steric bulk, but 8 forms 6-, while 12 forms 7-membered chelate rings in their coordination compounds. The chelate size variation results in a markedly different coordination behavior towards Pt(II). In their reactions with Pt(PhCN)₂Cl₂ at 1:1 stoichiometry 12 forms the expected Pt(12)Cl₂ complex, while 8 gives the cation quantitatively. In the kinetically controlled reaction is the major product even at a 8:Pt(PhCN)₂Cl₂ = 1:2 ratio. Most interestingly, at 1:1 ligand to precursor ratio, cation rearranges to Pt(8)Cl₂ within one day, indicating that the neutral complex is thermodynamically more favorable.     

Solid state coordination chemistry of molybdenum oxides with 1,2,3-triazole (Htrz): The crystal structures of [Cu(I)Cu(II)2(trz)2Mo4O13(OH)], [MoO3(Htrz)0.5] and [Cu(I)trz]

Hydrothermal chemistry was used to prepare the bimetallic organic-inorganic hybrid oxide [Cu(I)Cu(II)₂(trz)₂Mo₄O₁₃(OH)] · 6H₂O (1 · 6H₂O). The structure consists of chains linked through into a three-dimensional framework. The structures of the simple metal-triazole phases [MoO₃(Htrz)_0.5] (2) and [Cu(trz)] (3) are also reported. Compound 2 is two-dimensional, constructed from corner-sharing {MoO₅N} octahedra. Compound 3 consists of {Cu(trz)}_n chains linked through weak Cu?Cu contacts into a virtual layer.     

Synthesis and characterization of new AMTTO-imine-ligands and their silver(I) complexes: crystal structures of TAMTTO, [Ag2(TAMMTO)4](NO3)2 · 4MeOH, [Ag(TAMTTO)(PPh3)2]NO3 · 1.5THF, [Ag(FAMTTO)(PPh3)2]NO3

Reaction of 4-amino-6-methyl-1,2,4-triazin-thione-5-one (AMTTO, 1) with 2-thiophenecarboxaldehyde and 2-furaldehyde led to the corresponding iminic compounds 6-methyl-4-[thiophene-2-yl-methylene-amino]-3-thioxo-[1,2,4]-triazin-3,4-dihydro(2H)-5-one (TAMTTO, 2) and 4-[furan-2-yl-methylene-amino]-6-methyl-3-thioxo-[1,2,4]-triazin-3,4-dihydro(2H)-5-one (FAMTTO, 3). Treatment of 2 with AgNO₃ gave the complex [Ag₂(TAMMTO)₄](NO₃)₂ · 4MeOH (4) and of 2 and 3 with [Ag(PPh₃)₂]NO₃ gave the complexes [Ag(TAMTTO)(PPh₃)₂]NO₃ · 1.5THF (5) and [Ag(FAMTTO)(PPh₃)₂]NO₃ (6), respectively. All the compounds have been characterized by elemental analyses, IR spectroscopy and mass spectrometry. Compound 2 and all the complexes have been characterized by X-ray diffraction studies, respectively. In addition, 5 and 6 have been characterized by ³¹P NMR spectroscopy. Crystal data for 2 at −80 °C: monoclinic, space group C2/c, a=2319.6(2), b=609.8(1), c=1673.6(2) pm, β=106.14(1)°, Z=8, R₁=0.0523; for 4 at −80 °C: triclinic, space group , a=877.6(1), b=1085.2(1), c=1557.7(2) pm, α=77.14(1)°, β=80.87(1)°, γ=78.18(1)°, Z=1, R₁=0.0407; for 5 at 20 °C: triclinic, space group , a=1151.1(2), b=1225.1(2), c=1887.4(3) pm, α=78.04(1)°, β=86.20(1)°, γ=76.03(1)°, Z=2, R₁=0.0662; for 6 at −80 °C: triclinic, space group , a=1189.7(2), b=1387.8(2), c=1410.9(2) pm, α=94.74(2)°, β=95.12(2)°, γ=112.41(2)°, Z=2, R₁=0.0511.     

Structural analysis and magnetic properties of the copper(II) dicyanamide complexes [Cu2(dmphen)2(dca)4], [Cu(dmphen)(dca)(NO3)]n and [Cu(4,4-dmbpy)(H2O)(dca)2] (dca=dicyanamide; dmphen=2,9-dimethyl-1,10-phenanthroline; 4,4-dmbpy=4,4-dimethyl-2,2-bipyridine)

The preparation, crystal structures and magnetic properties of three copper(II) compounds of formulae [Cu₂(dmphen)₂(dca)₄] (1), [Cu(dmphen)(dca)(NO₃)]_n (2) and [Cu(4,4^′-dmbpy)(H₂O)(dca)₂] (3) (dmphen=2,9-dimethyl-1,10-phenanthroline, dca=dicyanamide and 4,4^′-dmbpy=4,4^′-dimethyl-2,2^′-bipyridine) are reported. The structure of 1 consists of discrete copper(II) dinuclear units with double end-to-end dca bridges whereas that of 2 is made up of neutral uniform copper(II) chains with a single symmetrical end-to-end dca bridge. Each copper atom in 1 and 2 is in a distorted square pyramidal environment: two (1) or one (2) nitrile-nitrogen atoms from bridging dca groups, one of the nitrogen atoms of the dmphen molecule (1 and 2) and either one nitrile-nitrogen from a terminal dca ligand (1) or a nitrate-oxygen atom (2) build the equatorial plane whereas the second nitrogen atom of the heterocyclic dmphen fills the axial position (1 and 2). The copper-copper separations through double (1) and single (2) end-to-end dca bridges are 7.1337(7) (1) and 7.6617(7) (2). Compound 3 is a mononuclear copper(II) complex whose structure contains two neutral and crystallographically independent [Cu(4,4^′-dmbpy)(H₂O)(dca)₂] molecules which are packed in two different layer arrangements running parallel to the bc-plane and alternating along the a-axis. The copper atoms in both molecules have slightly distorted square pyramidal surroundings with the two nitrogen atoms of the 4,4^′-dmbpy ligand and two dca nitrile-nitrogen atoms in the basal plane and a water oxygen in the apical position. A semi co-ordinated dca nitrile-nitrogen from a neighbour unit [2.952(6) Å for Cu(2)-N] is in trans position to the apical water molecule in one of the two molecules, this feature representing part of the difference in supramolecular connections in the alternating layers referred to above. Magnetic susceptibility measurements for 1-3 in the temperature range 1.9-290 K reveal the occurrence of weak antiferromagnetic interactions through double [J=−3.3 cm⁻¹ (1), ] and single [J=−0.57 cm⁻¹ (2), ] dca bridges and across intermolecular contacts [θ=−0.07 K (3)].     

Syntheses and structures of two copper-molybdate complexes: The 3-D [Cu(4,4′-bpy)(MoO4)] and 1-D [Cu2(HDABCO)2(H2Mo8O27)] · 4H2O

Hydrothermal reaction of molybdenum oxide and copper(II) source in the presence of 4,4′-bipyridine (4,4′-bpy) afforded three-dimensional covalent framework [Cu^II(4,4′-bpy)(MoO₄)] (1), while reaction with 1,4-diazoniabicyclo[2,2,2]octane (DABCO) in place of 4,4′-bpy and addition of metal molybdenum resulted in one-dimensional chain-like compound . The copper in 1 is divalent and approximately shows trigonal bipyramidal geometry, while in 2 is monovalent and approximately shows T-shaped geometry. The structure of 1 has a three-dimensional pillar-layered framework constructed from bimetallic {CuMoO₄} layers bridged by bifunctional ligand 4,4′-bpy. Interestingly, the {CuMoO₄} layer in 1 consists of 16-membered {Cu₄Mo₄O₈} rings and 8-membered {Cu₂Mo₂O₄} rings, different from other reported {CuMoO₄} layers. The structure of 2 consists a one-dimensional chain that is attached by peripheral {Cu(HDABCO)}²⁺ units. The chain is constructed from octamolybdates through common corners.     

Anionic effects on the formation of tridentate 4′-chloro-2,2′:6′,2″-terpyridine copper(II) complexes having 1:1 or 1:2 ratio of metal and ligand and their crystal symmetry

A facile synthetic procedure has been used to prepare one five-coordinate and four six-coordinate copper(II) complexes of 4′-chloro-2,2′:6′,2″-terpyridine (tpyCl) ligand with different counterions (, , , , and ) in high yields. They are formulated as [Cu(tpyCl-κ³N,N′,N′′)(SO₄-κO)(H₂O-κO)] · 2H₂O (1), trans-[Cu(tpyCl-κ³N,N′,N″)(NO₃-κO)₂(H₂O-κO)] (2), [Cu(tpyCl-κ³N,N′,N″)₂](BF₄)₂ (3), [Cu(tpyCl-κ³N,N′,N″)₂](PF₆)₂ (4) and [Cu(tpyCl-κ³N,N′,N″)₂](ClO₄)₂ (5) and versatile interactions in supramolecular level including coordinative bonding, O-H?O, O-H?Cl, C-H?F, and C-H?Cl hydrogen bonding, π-π stacking play essential roles in forming different frameworks of 1-5. It is concluded that the difference of coordination abilities of the counterions used and the experimental conditions codominate the resulting complexes with 1:1 or 1:2 ratio of metal and ligand.     

Luminescent metalloreceptors with pendant macrocyclic ionophore: Synthesis, characterization, electrochemistry and ion-binding study

Metalloreceptors containing ruthenium(II) bipyridine unit as fluorophore and pendant macrocyclic units as ionophore have been synthesized and their luminescence and electrochemical properties have been investigated. Ion-binding study of these fluoroionophore with the anions F⁻, Cl⁻, Br⁻, I⁻, , , , , CH₃COO⁻, and and cations Na⁺, K⁺, Mg²⁺, Ca²⁺, Zn²⁺, Ba²⁺, Sr²⁺ Cd²⁺, Hg²⁺, Pb²⁺ and Cu²⁺, monitored by luminescence and ¹H NMR spectral changes, reveal strong interactions of and F⁻ for 2 and 3 and of Cu²⁺ only for 3. Luminescence titrations for 2 and 3 have been carried out to determine binding constants (K_s), and the calculated values are in the range 2.85 × 10² to 4.48 × 10⁴ M⁻¹. The ¹H NMR spectral changes for 2 and 3 with the addition of increasing concentration of F⁻ and exhibit substantial low-field shift of the CONH proton indicating its involvement in complex formation with the anions. The adduct of 2 and 3 have been isolated and characterized by ¹H and ³¹P NMR, mass and IR spectroscopy. The results are discussed in light of selectivity, structures of the anion bound complexes and their luminescence property.     

Synthesis and characterization of cis-[(PPh3)2Pt{9-MeAd(-H),NN}]X (X = NO3, PF6): The first example of a platinum(II) complex containing the N,N-chelated 9-methyladenine anion

Reaction between the binuclear hydroxo complex cis-[(PPh₃)₂Pt(μ-OH)]₂X₂ (X⁻ = NO₃, 1a; , 1b) and the model DNA base 9-methyladenine (9-MeAd) leads to the formation of the mononuclear species cis-[(PPh₃)₂Pt{9-MeAd(-H),N⁶N⁷}]X (X⁻ = NO₃, 2a; PF₆, 2b), in which the nucleobase chelates the Pt(II) ion with the N6 and N7 atoms. The coordination mode of the nucleobase has been determinated through a multinuclear (¹H, ³¹P, ¹³C, ¹⁵N and ¹⁹⁵Pt) NMR analysis and the nuclearity of the complex has been obtained by E.S.I. mass spectrometry. 2 represents the first example of an isolated platinum complex in which the NH₂-deprotonated adenine exhibits this binding mode.     

Zinc complexes of a new N3O ligand and their biomimetic reactions

The new N₃O ligand 2-(pyridylmethylamino)-3-(3,5-dimethylpyrazol-1-yl)-propionic acid (L1H) was synthesized and converted to L1Zn-Cl and L1Zn-Br. These complexes are tetrameric in the solid state with bridging carboxylate functions. The reaction of deprotonated L1H with zinc nitrate or zinc perchlorate yielded the aqua complexes [L1Zn-OH₂] X with and , which crystallize as carboxylate-bridged dimers. Their deprotonation produced, in situ, the hydroxide complex L1Zn-OH, which acted as a base toward p-nitrophenol and bis(p-nitrophenyl)phosphoric acid resulting in L1Zn-ONit and L1Zn-OPO(ONit)₂. Tris(p-nitrophenyl)phosphate was cleaved hydrolytically by L1Zn-OH, releasing one p-nitrophenyl group. A kinetic investigation of this cleavage reaction under pseudo-first-order conditions has yielded second-order rate constants k″ of 0.9 s⁻¹ M⁻¹ in 50% aqueous DMSO and 4.0 s⁻¹ M⁻¹ in 75% aqueous DMSO.     

A trinuclear copper(II) complex with 2,5-pyridine-dicarboxylato bridges - [Cu3(2,5-pydc)2(Me5dien)2(H2O)2(BF4)2] · H2O: Synthesis, crystal structure and magnetic properties

A trinuclear copper(II) complex, [Cu₃(2,5-pydc)₂(Me₅dien)₂(BF₄)₂(H₂O)₂] · H₂O 1, has been constructed from 2,5-pyridine-dicarboxylato bridges (2,5-pydc²⁻) and N,N,N′,N″,N″-pentamethyl-diethylenetriamine (Me₅dien) acting as a blocking ligand. The copper ions, within the centrosymmetric trinuclear cations, are connected by two 2,5-pydc²⁻ bridges, with an intramolecular Cu···Cu separation of 8.432 Å. The central copper ion exhibits an elongated octahedral geometry, with semicoordinated ions, while the terminal ones are pentacoordinated (distorted square-pyramidal geometry). The cryomagnetic investigation of 1 reveals an antiferromagnetic coupling of the copper(II) ions (J = −5.9 cm⁻¹, H = −JS_Cu1S_Cu2 − JS_Cu2S_Cu1a).     

Rhenium(IV) cyanate complexes: Synthesis, crystal structures and magnetic properties of NBu4[ReBr4(OCN)(DMF)] and (NBu4)2[ReBr(OCN)2(NCO)3]

Two new rhenium(IV) mononuclear compounds of formula NBu₄[ReBr₄(OCN)(DMF)] (1) and (NBu₄)₂[ReBr(OCN)₂(NCO)₃] (2) (NBu₄ = tetrabutylammonium cation, OCN = O-bonded cyanate anion, NCO = N-bonded cyanate anion and DMF = N,N-dimethylformamide) have been synthesized and their crystal structures determined by single-crystal X-ray diffraction. 1 crystallizes in the monoclinic system with the space group P2₁/n, whereas 2 crystallizes in the triclinic one with as space group. In both complexes the rhenium atom is six-coordinated, in 1 by four Br atoms in the equatorial plane, and two trans-oxygen atoms, one of a DMF molecule and another one from a cyanato group, while in 2 by one bromide anion and five cyanate ligands, two of which are O-bonded and three N-bonded, forming a somewhat distorted octahedral surrounding. Magnetic susceptibility measurements on polycrystalline samples of 1 and 2 in the temperature range 1.9-300 K are interpreted in terms of magnetically isolated spin quartets with large values of the zero-field splitting (|2D| is ca. 41.6 and 39.2 cm⁻¹ for 1 and 2, respectively).     

Polymorphism in intercluster salt system: two crystal structures of [Al13O4(OH)24(H2O)12][H2W12O40](OH) · nH2O

In this paper, we report the syntheses and crystal structures of two intercluster salt compounds, [Al₁₃O₄(OH)₂₄(H₂O)₁₂][H₂W₁₂O₄₀](OH) · 20H₂O (1) and [Al₁₃O₄(OH)₂₄(H₂O)₁₂][H₂W₁₂O₄₀](OH) · 24H₂O (2). The crystal structures of these compounds show that they are polymorphs to each other with different modes of packing of the and ions. The structures of 1 and 2 can be described as alternating arrangements of ionic clusters that optimize electrostatic interactions and hydrogen bonds between them. The structure of 1 is analogous to the PtS structure and that of 2 is similar to the β-BeO structure with the clusters forming tetrahedral or square planar coordination geometries to each other.     

Carboxylate and dicarboxylate derivatives of [Et4N][Re2(CO)6(OR)3] (R = H or Me)

The ligand exchange reaction of the anionic binuclear rhenium complexes (R = H (1) or Me (2)) has been studied with the carboxylic acids; benzoic acid (3, 4, and 5), fumaric acid (6), and terephthalic acid (7). The exchange with benzoic acid can be controlled by stoichiometry to one, two, or three substitutions. The doubly (4) and triply (5) substituted complexes represent new structural motifs for the triply bridged Re₂(CO)₆ unit. The dicarboxylic acids fumaric and terephthalic bridge two dirhenium centers. Crystal structure determinations have been carried out for the new complexes synthesized.     

Metallocycle and ring-opening polymerization of silver(I) complexes with 1,3-bis(4,5-dihydro-1H-imidazol-2-yl)benzene ligand

The reaction of 1,3-bis(4,5-dihydro-1H-imidazol-2-yl)benzene (bib) ligand with silver(I) nitrate in a 1:1 molar ratio generated a [2 + 2] metallocyclic complex [Ag₂(bib)₂](NO₃)₂ · 2H₂O, in which bib ligand displayed in cis configuration. When the additional competing ligands/counterions, such as oxlate salt, 1,2-diaminoethene (en), 1,3-diaminopropane (pn), and were introduced, respectively, to the above-mentioned reaction solution, ring-open polymerization of sliver(I) complexes {[Ag(bib)]NO₃ · H₂O}_n (1), {[Ag(bib)₂]X}_n ( (2), (3)), {[Ag₂(bib)₂(NO₂)](NO₂) · 19/8H₂O}_n (4) and {[Ag₂(bib)₂](V₄O₁₂)_0.5 · 3H₂O · 2MeCN}_n (5) were generated. In compounds 1, 4 and 5, bib ligand adopts trans configuration and twists around the Ag-Ag axis, giving rise to single-stranded helical structure with short adjacent Ag?Ag distances of 3.56, 3.56, 3.50 and 3.63 Å, respectively. Compounds 2 and 3 are 1D coordination polymers fusing the [2 + 2] metallocycle [Ag₂(bib)₂]²⁺, in which bib ligand exhibits in cis configuration and the metallocycles have longer Ag?Ag distances of 8.52 Å in 2 and 8.61 Å in 3 along with the strong intracyclicπ-π interactions between phenyl groups. Cis and trans configurations of bib coexist in solution and crystallize in complexes 1 and 2 in the solid state in the presence of en or pn. The solution of 1 and 2 can be converted into 3 via the addition of the bulky counter anion or into 4 through introduction of the competing ligand/conuterion .     

Synthesis and structures of copper and gold complexes of the P,N ligands RNC(Bu)C(H)RPPh2 (R = SiMe3, H)

The reaction of the chelating P,N ligand RNC(Bu^t)CH(R)PPh₂ (R = SiMe₃) (1) with CuCl and CuCl₂ (probably by way of reduction to Cu(I) by the phosphine ligand) or Cu(NCCH₃)₄ClO₄ yielded the dimeric 1:1 complex [Cu{PPh₂CH(R)C(Bu^t)NR}Cl]₂ (2) or the monomeric 2:1 complex [Cu{PPh₂CH(R)C(Bu^t)NR}₂]ClO₄ (3), respectively. The presence of trace amounts of water during the reaction resulted in the successive cleavage of the two trimethylsilyl groups of the ligand and the formation of the monomeric chelate complexes [Cu{PPh₂CH(R)C(Bu^t)NH}₂]ClO₄ (4) and [Cu{PPh₂CH₂C(Bu^t)NH}₂]ClO₄ (5). Oxidation of 5 by atmospheric oxygen led to small quantities of the blue Cu(II) complex [Cu{(O)PPh₂CH₂C(Bu^t)NH}₂](ClO₄)₂ (6). The dimeric gold complexes [Au{PPh₂CH₂C(Bu^t)NH}]₂X₂ (X = BF₄, ClO₄) (7) were similarly obtained from the previously described Au{PPh₂CH(R)C(Bu^t)NR}Cl by replacing the covalently bound chlorine with the weakly coordinating anions in the presence of small quantities of water. The solution and solid state structures (except 5) of all complexes were determined by NMR spectroscopy and X-ray crystallography.     

Mononuclear cobalt(II) carboxylate complexes: Synthesis, molecular structure and selective oxygenation study

Some cobalt carboxylate (both mononuclear as well as binuclear) complexes have been prepared by using hindered hydrotris(3,5-diisopropyl-1-pyrazolyl)borate (Tp^iPr2) as supporting ligand. The reaction of [Tp^iPr2Co(NO₃)] (2) with sodium benzoate resulted in the formation of acetonitrile coordinated complex [Tp^iPr2Co(OBz)(CH₃CN)] (3) whereas the reaction of 2 with sodium fluorobenzoate gave coordinately unsaturated five coordinate complex of the type [Tp^iPr2Co(F-OBz)] (4). The oxidation of compound 4 in the presence of 3,5-diisopropylpyrazole resulted in the formation of a unique compound (5) where only one methine carbon of isopropyl group on pyrazole ring of hydrotris(3,5-diisopropyl-1-pyrazolyl)borate oxidized and coordinated with cobalt center. In compound 5, the binding behavior of fluorobenzoate also changes from bidentate to monodentate and the nonbonded oxygen atom formed intramolecular hydrogen bond with the hydrogen atom of the NH fragment of the coordinated . X-ray crystallography and IR studies confirmed the existence of hydrogen bonding in complex 5. The pyrazolato bridged binuclear cobalt(II) complex (6) was prepared by the reaction of hydrated cobalt(II) nitrate, 3,5-diisopropylpyrazole and sodium nitrobenzoate where, each cobalt is four coordinate. The X-ray structure of 6 showed that the NH fragment of terminally coordinated formed intramolecular hydrogen bonding with nonbonded oxygen atom of monodentately coordinated nitrobenzoate.     

The synthesis and characterization of iron cyanide building blocks: [K]2[CpFe(CN)3] and its pentamethylcyclopentadienyl (Cp*) analog

The synthesis of [K]₂[CpFe(CN)₃] (1) and its pentamethylcyclopentadienyl analog (2) has been described via the photolysis of the corresponding [K][CpFe(CO)(CN)₂] salts in methanol in the presence of KCN. The structure of complex 1 has been characterized by means of X-ray crystallography, where the potassium ions are interacting with the N atoms of the cyanide ligands. As expected, the average ν_CN stretching frequency in the anion is 16 cm⁻¹ higher than that in the more electron-donating pentamethylcyclopentadienyl derivative.     

Complexes containing the [TeCl4X] moiety (X = Cl or an aryl group)

Treatment of TeCl₄ with either K[{N(C₆H₃Prⁱ₂-2,6)C(H)}₂CPh] [≡K(L)] (1) in thf/Et₂O or [H₂(L)]Cl (2) in Et₂O furnished [Cl₄Cl?HH?OEt₂]·0.5(Et₂O) (3), whilst 2TeCl₄ with a mixture of single equivalent portions of 2,6-Prⁱ₂C₆H₃NH₂ and H(L) produced [Cl₄] (4). The X-ray structures of each of crystalline 3 and 4 show that the Te atom is at the centre of an only slightly distorted square pyramid, with a Cl atom of 3 or a C of 4 in the axial position. The N1 and N2 atoms of the π-delocalised β-dialdiminium moiety of 3 have H-bond contacts, involving short N1-H?OEt₂ and N2-H?Cl5 distances. The two longer of the four Te-Cl bonds of 4 are close to the N atom of the neighbouring molecule; whilst two of the H atoms of each H₃ fragment are H-bonded to the O atoms of the two thf ligands, the third being close to two Cl atoms of an adjacent molecule, thus forming H-bonded chains of molecules.