Supramolecular approach to crystallization of polynuclear chromium(III) aqua hydroxo complexes: synthesis and crystal structures of complexes [Cr2(OH)2(H2O)8]4+ and [Cr4(OH)6(H2O)12]6+ with cucurbit[n]uril (n = 7, 8)

Supramolecular compounds of the compositions {[Cr₂(OH)₂(H₂O)₈](C₄₂H₄₂N₂₈O₁₄)₂}-(NO₃)₄·18.75H₂O (1) and {[Cr₄(OH)₆(H₂O)₁₂](C₄₈H₄₈N₃₂O₁₆)₃(NO₃)₆·55H₂O (2) were synthesized from aqueous solutions of chromium(III) nitrate and the macrocyclic cavitand cucurbit[n]uril (C_6n H_6n N_4n O_2n , where n = 7 or 8, respectively). According to the X-ray diffraction study, the polynuclear chromium aqua complexes are disposed in cavities formed by the cucurbit[n]uril molecules and are linked to these molecules through hydrogen bonds between the hydroxo and aqua ligands of the polycations and the portal oxygen atoms of the macrocycles. Compound 1 is the first example of supramolecular compounds of cucurbit[7]uril with metal aqua complexes. The isolation of the supramolecular adduct with cucurbit[8]uril 2 in the single-crystalline state allows the determination of the structure of the tetranuclear chromium aqua complex having an adamantane-like structure, [Cr₄(μ₂-OH)₆(H₂O)₁₂]⁶⁺, which has been previously unknown in the solid state.     

Triplet electronic states in d(2) and d(8) complexes probed by absorption spectroscopy: a CASSCF/CASPT2 analysis of [V(H2O)6]3+ and [Ni(H2O)6]2+

Octahedral complexes of transition metal ions with d(2) and d(8) electron configurations have triplet electronic states with identical T(2g), A(2g), T(1g)((3)F), and T(1g)((3)P) symmetry labels. CASSCF and CASPT2 calculations indicate the predominant electronic configurations for each triplet state. The two (3)T(1g) states show strong configuration mixing in the d(8) complex [Ni(H(2)O)(6)](2+), but much weaker mixing occurs between these states in the d(2) compound [V(H(2)O)(6)](3+). Calculated vibrational frequencies and equilibrium geometries for the triplet states are used to obtain theoretical absorption spectra that are in agreement with the experimental data.     

Tricarbonylchromium complexes of [5]- and [6]metacyclophane: an experimental and theoretical study

Tricarbonylchromium complexes of [5]- and [6]metacyclophane were prepared and the interaction between the Cr(CO)₃ tripod and the cyclophane fragment was evaluated by both an experimental and a theoretical study. The tricarbonylchromium complex of [5]metacyclophane could only be obtained in solution and was characterized by its ¹H NMR spectrum. The tricarbonylchromium complex of [6]metacyclophane was isolated and an X-ray crystal structure was obtained, which reveals that no significant geometric changes occur upon coordination of the severely distorted aromatic ring. Computations on the tricarbonylchromium complexes of m-xylene, [5]- and [6]metacyclophane furthermore demonstrate that the corresponding complexation energy is remarkably unaffected by the degree of distortion of the aromatic ring. Theoretical analyses of the above model systems as well as complexes of planar and artificially deformed benzene with Cr(CO)₃ show that this is primarily the result of two counteracting effects: (i) a stabilization due to an increased back-donation from the metal center to the benzene and (ii) a destabilization due to the increasing strain in the aromatic ring.     

Theoretical study on photoinduced magnetization process: Possible meta-stable molecular structure for a photomagnetic high-spin molecule [MoIV(CN)2(CN-CuL)6]8+

An intermediate in photoinduced magnetization process for the photomagnetic high-spin molecule [Mo^IV(CN)₂(CN-CuL)₆]⁸⁺ is studied with quantum chemistry calculations of the density functional theory and the ab initio multireference configuration interaction methods. It is found that the intramolecular electronic transfer from Mo^IV to Cu^II leads one trigonal-bipyamid coordinated Cu^II to be changed to the tetrahedral coordinated Cu^I with the light irradiation. The calculated magnetic properties show that the paramagnetic system [Mo^IV(CN)₂(CN-Cu^IIL)₆]⁸⁺ with six isolated spin 1/2 Cu ions is changed to ferromagnetic coupling high-spin system [Mo^V(CN)₂(CN-Cu^IIL)₅(CN-Cu^IL)]⁸⁺. These calculations will help to understand photoinduced magnetization phenomenon and provide a clue for the synthesization of new reversible photoinduced magnetic compounds.     

Self-assembly of an Unprecedented Cynao-bridged One-dimensional 4f-3d Complex[Eu(DMF)4(H2O)2Cr(CN)6] H2O

Recently, there has been considerable interest in cyano-bridged lanthanide(Ⅲ) hexacyanometalate(Ⅲ) complexes LnM(CN)₆·nH₂O (M=Fe, Cr and Co) because of their potential as catalytic, semiconductive, and magnetic materials.^[1-8] In this study, we employed N,N-dimethylformamide (DMF) as a hybrid ligand to construct a bimetallic complex[Eu(DMF)₄(H₂O)₂Cr(CN)₆]·H₂O. It was synthesized as yellow crystals by the self-assembly of anhydrous EuCl₃ and (Bu₄N)₃[Cr(CN)₆] in MeOH and DMF. Single-crystal X-ray diffraction analysis shows that it consists of a cyano-bridged chain structure. The Eu atom is eight-coordinate with a distorted bicapped square antiprism geometry. Six oxygen atoms of two water molecules and four DMF molecules and two nitrogen atoms of the bridging CN ligands are bound to Eu with the Eu-O distance ranging from 2.368(7) to 2.447(8) Å. The bridging cyanides coordinate to the Europium(Ⅲ) ion[N(l)-Eu=2.543(9) Å and N(3)-EuA=2.543(8) Å] in a bent fashion with the bond angles of 164.0(9) for C(1)-N(1)-Nd and 155.1(7)。for C(3)-N(3)-EuA (A denotes the symmetry transformation:-x+l,y-l/2,-z+3/2). Each Cr(CN)₆ coordinates to two Eu(Ⅲ) ions using two cis cyanide ligands, while each Eu(DMF)₄(H₂O)₂ group connects two Cr(CN)₆ moieties in a cis fashion, giving rise to an unprecedented chain structure. Crystal data:monoclinic, space group P2₁/c, a=13.151(2), b=12.905(2), c=19.186(2) Å, β=109.70(1)°, V=3065.5(7) ų,Z=4, ρ_obs=1.531 Mg m^-3, S=1.024,R1=0.0540, R_w=0.1616.     

[Mn(H2O)4(NCS)2](18-冠-6)的分子和晶体结构

报导了[Mn(H2O)4(NCS)2](18-冠-6)单晶的X射线结构分析.它的晶体正交晶系.锰(II)与两个硫氰酸根,四个水分子配合形成顺式八面体的配位分子,并通过其中的水分子与18-冠-6以氢键结合.     

Hydrolysis of [Pt(dien)H2O]2+ and [Pd(dien)H2O]2+ complexes in water

The hydrolysis of the [Pt(dien)H₂O]²⁺ and [Pd(dien)H₂O]²⁺ complexes has been investigated by potentiometry at 298 K, in 0.1 mol dm^–3 aqueous NaClO₄. Least-squares treatment of the data obtained indicates the formation of mononuclear and -hydroxo-bridged dinuclear complexes with stability constants: log ₁₁ = –6.94 for [Pt(dien)OH]⁺, log ₁₁ = –7.16 for [Pd(dien)OH]⁺, and also log ₂₂ = –9.37 for [Pt₂(dien)₂(OH)₂]²⁺ and log ₂₂ = –10.56 for [Pd₂(dien)₂(OH)₂]²⁺. At pH values > 5.5, formation of the dimer becomes significant for the Pt^II complex, and at pH > 6.5 for the Pd^II complex. These results have been analyzed in relation to the antitumor activity of Pt^II complexes.     

Intensely green quinonoid [Cr(CO)4(Ph2P)2C-C6H4-C(R)O2CR-P,P] complexes

Summary Ph₂PCH(Ph)PPh₂, prepared by treating Ph₂PCH₂Ph successively with n-BuLi and Ph₂PCl, reacts with group VI metal hexacarbonyls to give [M(CO)₄{Ph₂PCH(Ph)-PPh₂}], where M = Cr, Mo or W. The Cr complex [Cr(CO)₄{Ph₂PCH(Ph)PPh₂}] was deprotonated with MeLi and the resulting carbanion [Cr(CO)₄(Ph₂-PCPhPPh₂)]^– acylated with RCOCl (R = Ph or p-tolyl) to give the intensely green title compounds in which an aromatic ring has become a quinonoid.Author to whom all correspondence should be directed.     

Thermolysis of [Co(NH3)6][Cr(C2O4)3]

Thermolysis of the double-metal complex [Co(NH₃)₆][Cr(C₂O₄)₃] was studied in air at 200, 350, and 500°C and in a hydrogen atmosphere at 200, 350, 500, 700, and 900°C, as well as the composition and properties of thermolysis products. Oxidative thermolysis produces mixed oxides CoCr₂O₄ and Co₂CrO₄; reductive thermolysis produces Co + Cr₂O₃ mixture. Specific surface areas were measured for reductive thermolysis products; the maximal specific surface area and, therefore, maximal dispersion are reached at 500°C. The morphology of the reductive thermolysis products and the thermolysis chemism were studied in relation to the nature of the complex anion.     

Double complex salts [Ni(NH3)6]3[Fe(CN)6]2 and [Ni(NH3)6]3[Cr(CNS)6]2: Synthesis and properties

The double complex salts [Ni(NH₃)₆]₃[Fe(CN)₆]₂ and [Ni(NH₃)₆]₃[Cr(CNS)₆]₂ were synthesized and their thermal decomposition in air was studied. The values of interplanar distances in crystal lattices were determined. The compounds are proposed as precursors for producing homogeneous bimetallic nanodimensional powders.     

Crystal and molecular structure of [RuNO(NO2)4OHCuPy n ] heterometallic complexes

Heterometallic complexes [RuNO(NO₂)₄OHCuPy₂(H₂O)] (I) and [RuNO(NO₂)₄OHCuPy₃] (II) are described structurally for the first time. In complex I, the ruthenium anion is coordinated to the copper atom by the bridging OH group and two bridging nitro groups; in complex II, by the bridging OH group and one bridging nitro group. Dimers are formed in the crystal lattice of complex II due to the interaction of the copper atom and the nitro group of the ruthenium anion in trans position to the bridging NO₂ group.     

Electronic structure of oxidized complexes derived from cis-[Ru(II)(bpy)2(H2O)2]2+ and its photoisomerization mechanism

The geometry and electronic structure of cis-[Ru(II)(bpy)(2)(H(2)O)(2)](2+) and its higher oxidation state species up formally to Ru(VI) have been studied by means of UV-vis, EPR, XAS, and DFT and CASSCF/CASPT2 calculations. DFT calculations of the molecular structures of these species show that, as the oxidation state increases, the Ru-O bond distance decreases, indicating increased degrees of Ru-O multiple bonding. In addition, the O-Ru-O valence bond angle increases as the oxidation state increases. EPR spectroscopy and quantum chemical calculations indicate that low-spin configurations are favored for all oxidation states. Thus, cis-[Ru(IV)(bpy)(2)(OH)(2)](2+) (d(4)) has a singlet ground state and is EPR-silent at low temperatures, while cis-[Ru(V)(bpy)(2)(O)(OH)](2+) (d(3)) has a doublet ground state. XAS spectroscopy of higher oxidation state species and DFT calculations further illuminate the electronic structures of these complexes, particularly with respect to the covalent character of the O-Ru-O fragment. In addition, the photochemical isomerization of cis-[Ru(II)(bpy)(2)(H(2)O)(2)](2+) to its trans-[Ru(II)(bpy)(2)(H(2)O)(2)](2+) isomer has been fully characterized through quantum chemical calculations. The excited-state process is predicted to involve decoordination of one aqua ligand, which leads to a coordinatively unsaturated complex that undergoes structural rearrangement followed by recoordination of water to yield the trans isomer.     

Electronic structure and molecular properties of the heptacyanorhenate [Re(CN)7]3- and [Re(CN)7]4- complexes

We report scalar relativistic and Dirac scattered wave (DSW) calculations on the heptacyanorhenate [Re(CN)7](3-) and Re(CN)7(4-) complexes. Both the ground and lowest excited states of each complex split by spin-orbit interaction by about 0.3 eV. The calculated molecular electronegativities chi indicate that the open-shell complex is less reactive than the closed-shell complex, in agreement with experimental observations. The calculations indicate that the ground state spin density is highly anisotropic and that spin-orbit effects are responsible for the magnetic anisotropy of the molecular g tensor of the Re(CN)7(3-) complex. The calculated optical electronic transitions for both complexes with a polarizable continuum model using a time-dependent density functional (TDDFT)/B3LYP formalism are in reasonable agreement with those observed in the absorption spectrum.     

Encapsulation of Chloride-water cluster anion [Cl6(H2O)8]6- in a cage structure based [Cu(DMAP)4]2+ aggregation

A well chloride?water cluster [Cl₆(H₂O)₈]^6? in the complex [Cu₃(DMAP)₁₂Cl₆?8H₂O] (DMAP = N,N’-dimethyl p-aminopyridine) has been investigated structurally in the solid state. The chloride-water cluster [Cl₆(H₂O)₈]^6? is stabilized and orderly arranged by hydrogen bonds which display high symmetry. Six hosts [Cu(DMAP)₄]²⁺ cationic form a cage-like aggregation, and chloride-water [Cl₆(H₂O)₈]^6? cluster located in the cage. Cl^? anion play an important role to connect cubane-like (H₂O)₈ water cluster forming [Cl₆(H₂O)₈]^6? cluster, and on the other hand, to connect cage-like [Cu(DMAP)₄]²⁺ cationic aggregation by means of ionic electrostatic interaction and long-range coordinate bond interaction. The formation of such a cluster anion may be available for insight into the nature of hydration of chloride in H₂O.     

[Cr(H2O)3(NCS)3](18-冠-6)的分子和晶体结构

本文报道了[Cr(H2O)3(NCS)3](18-冠-6)配合物的单晶X射线结构 分析 , 并基于分析结果, 对分子的结构特点和晶胞中的堆积方式进行了讨论.     

A novel aggregate of [Mn2(mu-O)2] units: [Mn8O10(O2CMe)6(H2O)2(bpy)6]4+ with a serpentine core

The synthesis, characterization and initial reactivity studies are reported of the mixed-valence (Mn(IV)6Mn(III)2) title compound, which possesses an unusual serpentine-like core and is the highest average oxidation state (+3.75) Mn(x) (x > 4) cluster to date.     

Ortho‐Chalcogenotetrelate Anions as Chelating Ligands: Syntheses and Characterization of [K6(MeOH)9][Sn2Se6][Cr(en)2(SnSe4)]2, [Na(H2O)4][Cr(en)3]2[GeS3OH]2[Cr(en)2(GeS4)], and [Ba(H2O)10][{Cr(en)}2(GeSe4)2]

Reactions of K₄[SnSe₄], Na₄[GeS₄] or Ba₂[GeSe₄] with different 1,2‐diaminoethane (= en) coordinated complexes of CrCl₃ ([Cr(en)₂Cl₂]Cl or [Cr(en)₃]Cl₃) in MeOH or aqueous solution yielded three novel compounds that contain complexes of Cr³⁺ with ortho‐chalcogenotetrelate anions [E′E₄]^4? (E′ = Ge, Sn; E = S; Se): the crystal structures of [K₆(MeOH)₉][Sn₂Se₆][Cr(en)₂(SnSe₄)]₂ ( 1 ), [Na(H₂O)₄][Cr(en)₃]₂[GeS₃OH]₂[Cr(en)₂(GeS₄)] ( 2 ), and [Ba(H₂O)₁₀][{Cr(en)}₂(GeSe₄)₂] ( 4 ) have been determined by means of single crystal X‐ray diffraction ( 1 : triclinic space group ; lattice dimensions at 203 K: a = 1175.7(2), b = 1315.3(3), c = 1326.7(3) pm, α = 61.99(3)°, β = 64.05(3)°, γ = 83.57(3)°, V = 1617.4(6)·10⁶ pm³; R₁ [I > 2σ(I)] = 0.0788; wR₂ = 0.1306; 2 : monoclinic space group C2/c; lattice dimensions at 203 K: a = 2445.3(5), b = 1442.5(3), c = 1579.3(3) pm, β = 94.61(3)°, V = 5552.9(19)·10⁶ pm³; R₁ [I > 2σ(I)] = 0.0801; wR₂ = 0.2046; 4 : triclinic space group ; lattice dimension at 203 K: a = 1198.4(2), b = 1236.8(3), c = 1297.5(3) pm, α = 65.69(3)°, β = 63.35(3)°, γ = 81.21(3)°, V = 1565.2(5)·10⁶ pm³; R₁ [I > 2σ(I)] = 0.0732; wR₂ = 0.1855). 1 and 2 show the yet unprecedented complexation of transition metal ions by non‐bridging, single chalcogenotetrelate ligands to produce dinuclear, heterobimetallic complexes. Compound 2 contains the first structurally characterized complex with an ortho‐thiogermanate ligand. The formation of these compounds, and of a by‐product of 2 , [Cr(en)₃][GeS₃OH]·6H₂O ( 3 : monoclinic space group C2/c; lattice dimensions at 203 K: a = 2396.8(5), b = 1463.4(3), c = 1740.1(4) pm, β = 132.99(3)°, V = 4463.8(15)·10⁶ pm³; R₁ [I > 2σ(I)] = 0.0462; wR₂ = 0.1058), provides some insight in fundamental differences between the reaction behavior of [SnE₄]^4? anions one the one hand and [GeE₄]^4? anions on the other hand. The crucial role of the counterion charge becomes evident when comparing the structure motifs of the ternary anions in 1 and 2 with that observed in the Ba²⁺ compound 4 .     

DSC study of the phase transitions in [Ni(D2O)6](ClO4)2 and [Ni(H2O)6](ClO4)2

DSC measurements were carried out for [Ni(H₂O)₆](ClO₄)₂ (sampleH) and [Ni(D₂O)₆](ClO₄)₂ (sampleD) in the temperature range 300–380 K. For both compounds two anomalies on the DSC curves were detected. The results for sampleH are compared to those previously obtained using adiabatic calorimetry method. For both compounds studied in this work the high-temperature transition appears at the same temperature while the low-temperature one is shifted towards higher temperatures in sampleD. Disorder connected with H₂O or D₂O groups is suggested in the intermediate phase between the low- and high-temperature transitions.