Control of magnetic spin states by various mixed anionic ligands in trinickel complexes: synthesis, crystal structures and physical properties

This study provides an opportunity to control the magnetic spin of nickel atoms using various mixed anionic ligands. A series of linear trinickel complexes supported by two kinds of ligands, oligo-alpha-pyridylamido and sulfonyl amido/amido, were synthesized and their structures were determined by X-ray diffraction. The three nickel atoms of [Ni(3)(Lpts)(2)(dpa)(2)] (dpa(-) = dipyridylamido, Lpts(2-) = N,N'-bis(p-toluenesulfonyl)pyridyldiamido) display short Ni-N ( approximately 1.90 Angstrom) bond distances, which are consistent with a low spin state of Ni(II) ions, and exhibit spin states of (0, 0, 0) for the three Ni(II) ions. One of the terminal Ni(II) ions of [Ni(3)(Lms)(2)(dpa)(2)(H(2)O)] (Lms(2-) = N,N'-bis(4-methylsulfonyl)-pyridyldiamido) and [Ni(3)(Lpts)(2)(pepteaH(2))] (pepteaH(2)(2-) = pentapyridyldiamidodiamine) bonded with an axial ligand exhibits a square pyramidal (NiN(4)X) geometry with long Ni-N bond distances ( approximately 2.10 Angstrom) which are consistent with a high spin Ni(II) configuration. The spin states of these trinickel complexes are (1, 0, 0). Complexes interchanged by the removal or addition of an axial water molecule. The structural features of are comparable with those of . Both the terminal Ni(II) ions in [Ni(3)(LAc)(2)(dpa)(2)] (Lac(2-) = N,N'-biacetyl-pyridyldiamido) are in square pyramidal geometry and exhibit high spin. The spin states of the nickel ions in are (1, 0, 1), and the two terminal nickel ions exhibit antiferromagnetic interactions. The molecular structure of [Ni(3)(Lpts)(2)(dpa)(2)](BF(4)), which was obtained by the one-electron oxidation is similar to those of the neutral analogue , except for the presence of a counter anion to compensate for the positive charge on the Ni(3) core. All of the Ni-Ni bond lengths of are slightly shorter (ca. 0.05 Angstrom) than those in the neutral analogues. This is attributed to the formation of partial Ni-Ni bonding.     

Spin-crossover behavior in cyanide-bridged iron(II)-gold(I) bimetallic 2D Hofmann-like metal-organic frameworks

The synthesis and characterization of new two-dimensional (2D) cyanide-bridged iron(II)-gold(I) bimetallic coordination polymers formulated, {Fe(3-Xpy)2[Au(CN)2]2} (py = pyridine; X = F (1), Cl (2), Br (3), and I (4)) and the clathrate derivative {Fe(3-Ipy)2[Au(CN)2]2}.1/2(3-Ipy) (5), are reported. The iron(II) ion lies in pseudoctahedral [FeN6] sites defined by four [Au(CN)2](-) bridging ligands and two 3-Xpy ligands occupying the equatorial and axial positions, respectively. Although only compounds 2 and 4 can be considered strictly isostructurals, all of the components of this family are made up of parallel stacks of corrugated {Fe[Au(CN)2]2}n grids. The grids are formed by edge sharing of {Fe4[Au(CN)2]4} pseudosquare moieties. The stacks are constituted of double layers sustained by short aurophilic contacts ranging from 3.016(2) to 3.1580(8) A. The Au...Au distances between consecutive double layers are in the range of 5.9562(9)-8.790(2) A. Compound 5, considered a clathrate derivative of 4, includes one-half of a 3-Ipy molecule per iron(II) atom between the double layers. Compound 1 undergoes a half-spin transition with critical temperatures Tc downward arrow = 140 K and Tc upward arrow = 145 K. The corresponding thermodynamic parameters derived from differential scanning calorimetry (DSC) are Delta H = 9.8 +/- 0.4 kJ mol(-1) and Delta S = 68.2 +/- 3 J K mol(-1). This spin transition is accompanied by a crystallographic phase transition from the monoclinic P2(1)/c space group to the triclinic P1 space group. At high temperatures, where 1 is 100% high-spin, there is only one crystallographically independent iron(II) site. In contrast, the low temperature structural analysis shows the occurrence of two crystallographically independent iron(II) sites with equal population, one high-spin and the other low-spin. Furthermore, 1 undergoes a complete two-step spin transition at pressures as high as 0.26 GPa. Compounds 2- 4 are high-spin iron(II) complexes according to their magnetic and [FeN6] structural characteristics. Compound 5, characterized for having two different iron(II) sites, displays a two-step spin transition with critical temperatures of Tc(1) = 155 K, Tc(2) downward arrow = 97 K, and Tc(2) upward arrow = 110 K. This change of spin state takes place in both sites simultaneously. All of these results are compared and discussed in the context of other {Fe(L) x [M(I)(CN)2]} coordination polymers, particularly those belonging to the homologous compounds {Fe(3-Xpy)2[Ag(CN)2]2} and their corresponding clathrate derivatives.     

Synthesis, structural characterization, and theoretical studies of complexes of magnesium and calcium with gallium heterocycles

The magnesium- and calcium-gallium heterocycle complexes [Mg{Ga[(ArNCH)2]}2(THF)3] and [Ca{Ga[(ArNCR)2]}2(THF)4], R = H or Me, Ar = C6H3Pr(i)2-2,6, have been prepared via the reduction of [I2Ga{(ArNCR)2}] with the group 2 metal in tetrahydrofuran. The mechanisms of the reactions have been elucidated, and the crystal structures of the complexes exhibit the first structurally authenticated Ga-Mg and Ga-Ca bonds in molecular species. Theoretical studies suggest that the heterocycle-group 2 metal interactions have significant ionic character.     

A phosphine-mediated through-space exchange coupling pathway for unpaired electrons in a heterobimetallic lanthanide-transition metal complex

The reaction of P(CH2OH)3 with methyl anthranilate NH2C6H4-2-CO2Me produced the ligand precursor P(CH2NHC6H4-2-CO2Me)3 (1). The reaction of 1 with [Y{N(SiMe3)2}3] produced hexadentate yttrium complex [Y{P(CH2NC6H4-2-CO2Me)3}] (2), in which the metal centre is coordinated by three amido donors and the three carbonyl oxygen atoms of the ester groups. The 31P{1H} NMR spectrum features 1J Y,P=15 Hz, and DFT calculations demonstrate that through-space interaction between the minor lobe of the phosphine lone pair and the yttrium centre allows a large Fermi contact contribution to this spin coupling constant. The EPR spectrum of the analogous paramagnetic Gd complex [Gd{P(CH2NC6H4-2-CO2Me)3}] (3) can be modelled by using a B20 crystal field parameter of +/-0.19 cm(-1). Heterodinuclear complexes were prepared by the reactions of 1 and 3 with [5,10,15,20-tetrakis(4-methoxyphenyl)porphinato]cobalt(II), by binding of the phosphine lone pair to the d(7) cobalt centre. The solid-state EPR spectrum of the heterodinuclear yttrium complex 4 exhibits large superhyperfine coupling to the phosphorus nucleus, indicative of an S=1/2 complex in which the unpaired electron resides in the cobalt dz2 orbital directed at the phosphine donor. The magnetic susceptibility of the heterodinuclear Gd-Co complex 5 demonstrates that through-space antiferromagnetic coupling occurs between unpaired electrons on the gadolinium and cobalt centres.     

Syntheses and structures of magnesium and zinc boraamidinates: EPR and DFT investigations of Li, Mg, Zn, B, and In complexes of the [PhB(NtBu)2].- anion radical

The first magnesium and zinc boraamidinate (bam) complexes have been synthesized via metathetical reactions between dilithio bams and Grignard reagents or MCl2 (M = Mg, Zn). The following new classes of bam complexes have been structurally characterized: heterobimetallic spirocycles {(L)mu-Li[PhB(mu-NtBu)2]}2M (6a,b, M = Mg, L = Et2O, THF; 6c, M = Zn, L = Et(2)O); bis(organomagnesium) complexes {[PhB(mu3-NtBu)2](MgtBu)2(mu3-Cl)Li(OEt2)3} (8) and {[PhB(mu3-NtBu)2](MgR)2(THF)2} (9a, R = iPr; 9b, R = Ph); mononuclear complex {[PhB(mu-NDipp)2]Mg(OEt2)2} (10). Oxidation of 6a or 6c with iodine produces persistent pink (16a, M = Mg) or purple (16b, M = Zn) neutral radicals {Lx-mu-Li[PhB(mu-NtBu)2]2M}. (L = solvent molecule), which are shown by EPR spectra supported by DFT calculations to be Cs-symmetric species with spin density localized on one of the bam ligands. In contrast, characterization of the intensely colored neutral radicals {[PhB(mu-NtBu)2]2M}. (5c, M = In, dark green; 5d, M = B, dark purple) reveals that the spin density is equally delocalized over all four nitrogen atoms in these D2d-symmetric spirocyclic systems. Oxidation of the dimeric dilithio complex {Li2[PhB(mu4-NtBu)2]}2 with iodine produces the monomeric neutral radical {[PhB(mu-NtBu)2]Li(OEt2)x}. (17), characterized by EPR spectra and DFT calculations. These findings establish that the bam anionic radical [PhB(NtBu)2].- can be stabilized by coordination to a variety of early main-group metal centers to give neutral radicals whose relative stabilities are compared and discussed.     

Carbon-oxygen bond formation between a terminal alkoxo ligand and a coordinated olefin. Evidence for olefin insertion into a rhodium alkoxide

Preparation and reactivity of a series of bis(phosphine) rhodium(I) alkoxides stabilized by intramolecular olefin coordination are reported. {Rh(PEt3)2[kappa1:eta2-OCRR'(CH2)nCH=CH2]} (n = 1, 2) were prepared via alcoholysis of {Rh(PEt3)2[N(SiMe3)2]} by the corresponding alcohols HOCRR'(CH2)nCH=CH2. The in situ generated {Rh(PEt3)2[kappa1:eta2-OCRR'(CH2)2CH=CH2]} were not stable at ambient temperatures and decomposed in the presence of added PEt3 to afford 2,2-disubstituted-5-methylenetetrahydrofurans and [(PEt3)4Rh-H] in good to high yields. Kinetic and deuterium labeling results support a syn-oxyrhodation pathway via direct olefin insertion into a Rh-O bond, followed by rapid beta-hydride elimination. In comparison, {Rh(PEt3)2[kappa1:eta2-OCRR'CH2CH=CH2]} are isolated as stable crystals, and the Rh-olefin interactions are evidenced by an X-ray structure. Heating of these complexes generated [Rh(PEt3)2(eta2-allyl)] and the corresponding ketones in high yields following an apparent beta-allyl elimination pathway.     

(Fluoren-9-ylidene)methanedithiolato complexes of platinum: synthesis, reactivity, and luminescence

Platinum(II) complexes with (fluoren-9-ylidene)methanedithiolato and its 2,7-di-tert-butyl- and 2,7-dimethoxy-substituted analogues were obtained by reacting different chloroplatinum(II) precursors with the piperidinium dithioates (pipH)[(2,7-R2C12H6)CHCS2] [R = H (1a), t-Bu (1b), or OMe (1c)] in the presence of piperidine. The anionic complexes Q2[Pt{S(2)C=C(C12H6R(2)-2,7)}2] [R = H, (Pr(4)N)(2)2a; R = t-Bu, (Pr4N)(2)2b, (Et4N)(2)2b; R = OMe, (Pr4N)(2)2c] were prepared from PtCl(2), piperidine, the corresponding QCl salt, and 1a-c in molar ratio 1:2:2:2. In the absence of QCl, the complexes (pipH)(2)2b and [Pt(pip)(4)]2b were isolated depending on the PtCl(2):pip molar ratio. The neutral complexes [Pt{S2C=C(C12H6R(2)-2,7)L(2)] [L = PPh(3), R = H (3a), t-Bu (3b), OMe (3c); L = PEt(3), R = H (4a), t-Bu (4b), OMe (4c); L(2) = dbbpy, R = H (5a), t-Bu (5b), OMe (5c) (dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridyl)] were similarly prepared from the corresponding precursors [PtCl2L2] and 1a-c in the presence of piperidine. Oxidation of Q(2)2b with [FeCp2]PF6 afforded the mixed Pt(II)-Pt(IV) complex Q2[Pt2{S2C=C[C12H6(t-Bu)(2)-2,7]}4] (Q(2)6, Q = Et4N+, Pr4N+). The protonation of (Pr4N)(2)2b with 2 equiv of triflic acid gave the neutral dithioato complex [Pt2{S2CCH[C12H6(t-Bu)(2)-2,7]}4] (7). The same reaction in 1:1 molar ratio gave the mixed dithiolato/dithioato complex Pr4N[Pt{S2C=C[C12H6(t-Bu)(2)-2,7]}{S2CCH[C12H6(t-Bu)(2)-2,7]}] (Pr(4)N8) while the corresponding DMANH+ salt was obtained by treating 7 with 2 equiv of 1,8-bis(dimethylamino)naphthalene (DMAN). The crystal structures of 3b and 5c.CH2Cl2 have been solved by X-ray crystallography. All the platinum complexes are photoluminescent at 77 K in CH2Cl2 or KBr matrix, except for Q(2)6. Compounds 5a-c and Q8 show room-temperature luminescence in fluid solution. The electronic absorption and emission spectra of the dithiolato complexes reveal charge-transfer absorption and emission energies which are significantly lower than those of analogous platinum complexes with previously described 1,1-ethylenedithiolato ligands and in most cases compare well to those of 1,2-dithiolene complexes.     

Nitrogen atom insertion into Ir-S and C-S bonds initiated by photolysis of iridium(III)-azido-dithiocarbamato complexes

Photolysis of acetonitrile solutions of Cp*Ir(R2dtc)(N3) [Cp* = eta5-C5Me5, R2dtc = S2CNR2; R = Me (1) or Et (1')] at temperatures below 0 degrees C afford five-coordinate complexes Cp*Ir{NSC(NR2)S} (2 or 2'), where a nitrogen atom has been inserted into one of the Ir-S bonds. In solution, complex 2 thermally convert to the azaethene-1,2-dithiolate complex, Cp*Ir[SN=C(NMe2)S] (3), which could be crystallized as the corresponding dimer, {Cp*Ir[mu-SN=C(NMe2)S-kappa3S:S,S']}2 (4). As a result, a nitrogen atom that originated in the azide ligand is transferred into a C-S bond of the dithiocarbamate.     

Square‐Planar Ruthenium(II) Complexes: Control of Spin State by Pincer Ligand Functionalization

Functionalization of the PNP pincer ligand backbone allows for a comparison of the dialkyl amido, vinyl alkyl amido, and divinyl amido ruthenium(II) pincer complex series [RuCl{N(CH₂CH₂PtBu₂)₂}], [RuCl{N(CHCHPtBu₂)(CH₂CH₂PtBu₂)}], and [RuCl{N(CHCHPtBu₂)₂}], in which the ruthenium(II) ions are in the extremely rare square‐planar coordination geometry. Whereas the dialkylamido complex adopts an electronic singlet (S=0) ground state and energetically low‐lying triplet (S=1) state, the vinyl alkyl amido and the divinyl amido complexes exhibit unusual triplet (S=1) ground states as confirmed by experimental and computational examination. However, essentially non‐magnetic ground states arise for the two intermediate‐spin complexes owing to unusually large zero‐field splitting (D>+200 cm^?1). The change in ground state electronic configuration is attributed to tailored pincer ligand‐to‐metal π‐donation within the PNP ligand series.     

An unprecedented copper(I,II)-octacyanotungstate(V) 2-D network: crystal structure and magnetism of [CuII(tren)]{CuI[W(V)(CN)8]} . 1.5H2O

A novel two-dimensional cyanide-bridged polymer [CuII(tren)]{CuI[W(V)(CN)8]} . 1.5H2O (tren = tris(2-aminoethyl)amine) formed via the simultaneous in situ metal-ligand redox reaction of [Cu(tren)(OH2)]2+ and self-assembly with [W(V)(CN)8]3- consists of a {CuI[W(V)(CN)8]} square grid built of CuI centres of tetrahedral geometry coordinatively saturated by CN bridges and [W(V)(CN)8]3- capped by [CuII(tren)]2+ moieties; it exhibits ferromagnetic coupling J1 = +5.8(1) cm(-1) within the CuII-W(V) dinuclear subunits and weak antiferromagnetic coupling J2 = -0.03(1) cm(-1) between them through diamagnetic CuI spacers.     

Ln(terpy)]3+ (Ln = Sm, Gd) entity forms isolated magnetic chains with [W(CN)8]3-

The reaction between Ln(NO3)3*xH2O, Cs3[W(V)(CN)8]*H2O and 2,2':6',2'-terpyridine (terpy) leads to the original isomorphous cyano-bridged [Ln(III)(terpy)(DMF)4][W(V)(CN)8] *6H2O [Ln = Gd (1), Sm (2)] 1-D chains. The crystal structures of {Ln(III)W(V)} chains and consist of alternating {[W(CN)8]} and {[Ln(terpy)]} building blocks. The neighbouring 1-D chains are weakly linked through pi-pi stacking interactions of the aromatic rings leading to 2-D supramolecular layers. The layers are linked through hydrogen bonds between H2O molecules and terminal cyano ligands. Magnetic studies revealed a weak antiferromagnetic coupling (J = -2.3(2) K) within the {Gd(III)W(V)} chains in . The positive effective coupling constant J = +2.0(5) K between the total angular momentum of the Sm(III) centre and the spin of the W(v) ion is equivalent to an antiferromagnetic character of the spin coupling between both centres in the {Sm(III)W(V)} chains of 2. The magnetic measurements suggest that they display an isolated magnetic chain behaviour.     

Formation of Ga2Te2 and M3Te3(M = Ga, In) rings from reactions of sodium ditelluroimidodiphosphinate with Group 13 halides

Metathetical reactions of Na[N(iPr2PTe)2] with Group 13 metal halides produce the telluride complexes {Ga(mu-Te)[iPr2PNiPr2PTe]}2(2) and {M(mu-Te)[N(iPr2PTe)2]}3, M = In (3) and Ga (4), which contain central Ga2Te2 and M3Te3 rings, respectively.     

Synthesis and Molecular Structure of a C3‐chiral Triaminodistannane

Reaction of the chiral lithium stannate [HC{SiMe₂N[(S)–CH(Me)Ph]}₃SnLi(thf)] ( 1 ) with Me₃SnCl gave the corresponding distannane [HC{SiMe₂N[(S)–CH(Me)Ph]}₃Sn–SnMe₃] ( 2 ) in good yield. Its [2,2,2]bicyclooctane‐related cage structure, comprising the trisilylsilane unit and the triamido‐tin fragment, as well as the Sn–Sn bond (2.7978(15)–2.8020(15) Å in the three crystallographically independent molecules) were established by a single crystal X‐ray structure analysis: Space proup P3, Z = 3, lattice dimensions at 293(2) K: a = 17.724(3), c = 10.597(2) Å, R = 0.0374.     

Two supramolecular isomers of molecular squares and 1D helical chains with alternating right- and left-handed chirality

The reaction of [Ni(alpha-rac-L)](ClO4)2 with K2[Ni(CN)4] gives a cyanide bridged [2+2] type of molecular square, {cis-[Ni(f-rac-L)][Ni(CN)4]}2 (1). By slightly changing the reaction conditions, the reaction of [Ni(alpha-rac-L)](ClO4)2 with KCN leads to a metastable compound, cis-[Ni(f-rac-L)(CN)2] (2), and an unexpected 1D helical chain, {cis-[Ni(f-rac-L)][Ni(CN)4]}n (3). In 3, the 1D helical chains are packed in an alternating right- and left-handed chirality due to the oppositely twisted arrangements of two adjacent [Ni(CN)4]2- anions. The metastable compound 2 can be converted to 3 in a CH3CN/CH3OH solution. Compounds 1 and 3 are classified as supramolecular isomers, and isomer 3 can be considered to be formed by the ring-opening polymerization of the square precursor 1. Magnetic susceptibility measurements of 1 and 3 show that the adjacent six-coordinated Ni(II) atoms are antiferromagnetically coupled through the bent -NC-Ni-CN- bridges of the diamagnetic [Ni(CN)4]2- anions, with g = 2.08 and J = -0.426 cm(-1) for 1 and g = 2.08 and J = -0.278 cm(-1) for 3. The correlation between the structures and the J values is discussed.     

Synthesis, structure and catalytic activity of alkali metal-free bent-sandwiched lanthanide amido complexes with calix[4]-pyrrolyl ligands

Simple silylamine elimination reactions of calix[4]-pyrrole [R(2)C(C(4)H(2)NH)](4) (R = Me (1), {-(CH(2))(5)-}(0.5) (2)) with 2 equiv. of [(Me(3)Si)(2)N](3)Ln(μ-Cl)Li(THF)(3) (Ln = Nd, Sm, Dy) in reflux toluene, afforded the novel dinuclear alkali metal-free trivalent lanthanide amido complexes (η(5):η(1):η(5):η(1)-R(8)-calix[4]-pyrrolyl){LnN(SiMe(3))(2)}(2) (R = Me, Ln = Nd (3), Sm (4), Dy (5); R = {-(CH(2))(5)-}(0.5), Ln = Nd (6), Sm(7)). The complexes were fully characterized by elemental analyses, spectroscopic analyses and single-crystal X-ray analyses. X-ray diffraction studies showed that each lanthanide metal was supported by bispyrrolyl anions in an η(5) fashion and along with three nitrogen atoms from N(SiMe(3))(2) and two other pyrroyl rings in η(1) modes formed the novel bent-sandwiched lanthanide amido bridged trivalent lanthanide amido complexes, similar to ansa-cyclopentadienyl ligand-supported lanthanide amides with respect to each metal center. The catalytic activities of these organolanthanide complexes as single component l-lactide polymerization catalysts were studied.     

Longifoamide-A and B: Two new ceramides from Mentha longifolia (Lamiaceae)

Two new N-acylsphingosines (ceramides) named longifoamide A {6'-tetracosenamide, (6'-Z)-N-[2,3-dihydroxy-1-(hydroxymethyl)octadecyl]} and B {6'-tetracosenamide, (6'-Z)-N-[2,3,4-trihydroxy-1-(hydroxymethyl)octadecyl]} were isolated from a methanol extract of Mentha longifolia. Both ceramides were characterized with the aid of 1D and 2DNMR spectroscopic techniques and high resolution mass spectrometry.     

Electronic structure and bonding of {Fe(PhNO2)}6 complexes: a density functional theory study

Reduction of nitro-aromatic compounds (NACs) proceeds through intermediates with a partial electron transfer into the nitro group from a reducing agent. To estimate the extent of such a transfer and, therefore, the activity of various model ferrous-containing reductants toward NAC degradation, the unrestricted density functional theory (DFT) in the basis of paired L?wdin-Amos-Hall orbitals has been applied to complexes of nitrobenzene (NB) and model Fe(II) hydroxides including cationic [FeOH]+, then neutral Fe(OH)2, and finally anionic [Fe(OH)3]-. Electron transfer is considered to be a process of unpairing electrons (without the change of total spin projection Sz) that reveals itself in a substantial spin contamination of the unrestricted solution. The unrestricted orbitals are transformed into localized paired orbitals to determine the orbital channels for a particular electron-transfer state and the weights of idealized charge-transfer and covalent electron structures. This approach allows insight into the electronic structure and bonding of the {Fe(PhNO2)}6 unit (according to Enemark and Feltham notation) to be gained using model nitrobenzene complexes. The electronic structure of this unit can be expressed in terms of pi-type covalent bonding [Fe+2(d6, S = 2) - PhNO2(S = 0)] or charge-transfer configuration [Fe+3(d5, S = 5/2) - {PhNO2}- ((pi*)1, S = 1/2)].     

Heterometallic Cr-Mn complexes containing cyanide and oxalate bridges

Three heterometallic Cr-Mn compounds, {Mn(mu-ox)0.5(H2O) [Cr(phen)(CN)4]}n.n H2O.2n CH3OH, (1), {Mn(mu-ox)0.5(H2O)[Cr(bpy)(CN)4]}n.2n H2O x n CH3OH, (2), and {Mn(mu-ox)0.5(bpy)[Cr(bpy)(CN)4]}n, (3) (ox = oxalate), containing cyanide and oxalate bridges based on building blocks [Cr(L)(CN)4]- (L = phen and 2,2'-bipyridine) have been prepared. A new approach was first employed to synthesize ox-bridged compounds via facile oxidation-hydrolysis reactions of diaminomaleonitrile. X-ray crystallography revealed that the structures of 1 and 2 are similar, where cyano-bridged corrugated ladderlike chains are further connected through bis-bidentate oxalato bridges to unique two-dimensional layered structures. Of note is that the introduction of 2,2'-bipyridine led to an interesting cluster-based chainlike compound (3) with cyano-bridged squares [Mn2Cr2] extended by ox bridges. Magnetic studies show antiferromagnetic (AF) interaction between cyano-bridged Cr(III)-Mn(II) and ox-bridged Mn(II)-Mn(II) ions, with the result that 1 and 2 exhibit AF ordering with spin-flop behaviors below 18 and 19 K, respectively.     

Syntheses and Crystal Structures of two Ring—like {Mo18}Cluster Compounds

1INTRODUCTIONThepolyoxomolybdateshavebeenwidelyresearchedinmanyfieldssuchascatalysis,biology,medicineandmaterialsciencebecauseoftheirrichphysicalandchemicalproperties[1].Thoughmanypolyoxomolybdateshavebeenreported[2],furtherresearchisstillnecessaryforthestudyof搑eduction-oxidation-reconstitution?self-assemblyprocesses[3,4].Polyoxomolybdatesarenormallybuiltupundersuitableconditionsbyafewbuildingblockssuchas{Mo2},{Mo8}and{Mo9}inself-assemblyway[5,6].The{Mo18}clustershaveseveralstructuralty…     

Cucurbit[8]uril-based inclusion compounds containing iron(II), cobalt(III), and nickel(II) complexes with cyclam and cyclen as guest molecules: Synthesis and crystal structures

New inclusion compounds containing iron(II), cobalt(III), and nickel(II) complexes with the cyclic polyamine ligands cyclam and cyclen in the macrocyclic cavitand cucurbit[8]uril (CB[8]) were obtained: {trans-[Fe(Cyclam)(CO)(OCHO)]@CB[8]}Cl · 15H₂O, {cis-[Co(Cyclen)(H₂O)Cl]@CB[8]}Cl₂ · 20H₂O, and {cis-[Ni(Cyclen)(H₂O)Cl]@CB[8]}Cl · 12H₂O. According to X-ray diffraction data, the complexes are in the cavity of each CB[8] molecule. The complexes of the above molecular formulas were isolated in the solid state as supramolecular compounds with CB[8] and structurally characterized for the first time.