Supramolecular Cation Research Articles

Formation of p-Phenylenediamine−Crown Ether−[PMo12O40]4- Salts

Electron transfer from the electron donor of p-phenylenediamine (PPD) to the electron acceptor of (H+)3[PMo12O40]3- forms a one-electron-reduced Keggin cluster of [PMo12O40]4-, bearing a S = 1/2 spin, while proton transfer from the proton donor of (H+)3[PMo12O40]3- to the proton acceptor of PPD yielded mono- and diprotonated cations of 4-aminoanilinium (HPPD+) and p-phenylenediammonium (H2PPD2+). By introduction of crown ether receptors during the crystallization process, supramolecular cations of (HPPD+)(crown ethers) and/or (H2PPD2+)(crown ethers) were successfully introduced into three new alpha-[PMo12O40]4- salts of (H2PPD2+)2([12]crown-4)4[PMo12O40]4- (1), (HPPD+)4([15]crown-5)4[PMo12O40]4- (2), and (HPPD+)2(H2PPD2+)([18]crown-6)4[PMo12O40]4- (3) as the countercation. The protonated states of PPD and molecular-assembly structures of the supramolecular cations depended on the size of the crown ethers. In salt 3, a novel mixed-protonated state of HPPD+ and H2PPD2+ was confirmed to be complexed in the cation structure. According to the changes in the cation structures, the anion arrangements were modulated from those of the two-dimensional layer for salt 1 to the isolated cluster for salts 2 and 3. The temperature-dependent magnetic susceptibilities of salts 1-3 were consistent with the isolated spin arrangements of [PMo12O40]4-. The electronic spectra of salts 1-3 indicated the intervalence optical transition from pentavalent Mo(V) to hexavalent Mo(VI) ions within the [PMo12O40]4- cluster. Temperature-dependent electron spin resonance spectra of salt 2 revealed the delocalization-localization transition of the S = 1/2 spin at 60 K. The spin on the [PMo12O40]4- cluster was localized on a specific Mo(V) site below 60 K, which was thermally activated with an activation energy of 0.015 eV.

Structural Phase Transition of Magnetic [Ni(dmit)2]- Salts Induced by Supramolecular Cation Structures of (M+)([12]crown-4)2

Sandwich-type supramolecular cation structures of (M(+))([12]crown-4)(2) complexes (M(+) = Li(+), Na(+), K(+), and Rb(+)) were introduced as countercations to the [Ni(dmit)(2)](-) anion, which bears an S = (1)/(2) spin, to form novel magnetic crystals (dmit(2-) = 2-thione-1,3-dithiole-4,5-dithiolate). The zigzag arrangement of Li(+)([12]crown-4)(2) cations in Li(+)([12]crown-4)(2)[Ni(dmit)(2)](-) salt induced weak intermolecular interactions of [Ni(dmit)(2)](-) dimers, whose magnetic spins were isolated from each other. The molecular arrangements of cations and anions in M(+)([12]crown-4)(2)[Ni(dmit)(2)](-) salts (M(+) = Na(+), K(+), and Rb(+)) were isostructural to each other. In the case of Na(+)([12]crown-4)(2)[Ni(dmit)(2)](-), the space group C2/m changed to C2/c with a lowering in temperature from 298 to 100 K. This structural change occurred at 222.5 K as a first-order phase transition. The space group C2/m (T = 298 K) in the salt K(+)([12]crown-4)(2)[Ni(dmit)(2)](-) also changed to C2/c (T = 100 K), which transition occurred at 270 K. Crystal structural analyses at 298 and 100 K revealed changes in both supramolecular cation conformation and [Ni(dmit)(2)](-) anion arrangements. The transition from C2/m to C2/c crystals generated a dipole moment in the Na(+)([12]crown-4)(2) and K(+)([12]crown-4)(2) structures, which were reconstructed to cancel the net dipole moment of the C2/c crystals. These cation transformations led to changes in intermolecular interactions between the [Ni(dmit)(2)](-) anions via structural rearrangements. The crystal structure of C2/c was stabilized in Rb(+)([12]crown-4)(2)[Ni(dmit)(2)](-) at 298 K. The [Ni(dmit)(2)](-) configuration in these salts with the C2/c space group was a one-dimensional uniform chain, which showed the temperature-dependent magnetic susceptibility of a one-dimensional linear Heisenberg antiferromagnetic chain.

Crystal structures and magnetic properties of [Ni(dmit)2]− salts including (4-fluoroanilinium)([18]crown-6) and (4-methylanilinium)([18]crown-6) supramolecular cations

Abstract New supramolecular cation structures of (4-fluoroanilinium)([18]crown-6) and (4-methylanilinium)([18]crown-6) were introduced as counter cations to [Ni(dmit)2]− salts, which bear an S = 1/2 spin, to form magnetic crystals. From the crystal structures and temperature dependent magnetic susceptibilities, both salts had isomorphous structure of one-dimensional arrangements of [Ni(dmit)2]− π-dimer along the b-axis. The magnetic ground state of these salts was spin singlet with the intradimer magnetic exchange energy of around −150 K.

Salts of ammonium-crown ether supramolecular cation with bis(maleonitriledithiolato)copperate(II): Crystal structures, magnetic susceptibilities, single crystal EPR spectra and DFT calculation

Two salts consisting of ammonium-crown ether supramolecular cation with bis(maleonitriledithiolato)copperate (II), (NH 4) 2(15-crown-5) 3[Cu(mnt) 2] ( 1) and (NH 4) 2(benzo-15-crown-5) 4[Cu(mnt) 2] · 0.5H 2O ( 2), have been synthesized and structurally characterized. The distinct structures of supramolecular cation, an unusual triple-decker dication in 1 and a sandwich dimer in 2, were observed. X-band EPR studies on the single crystals of both 1 and 2 have been carried out at room temperature, which revealed that 1 possesses a single resonance line whereas 2 shows a perfect hyperfine structure. The spin-density distribution in the anionic moiety of 2 is calculated on DFT method and compared well with the experimental data.

Supramolecular Cations of (S)‐, (R)‐, and (RS)‐Indan‐1‐aminium(dibenzo[18]crown‐6) in Magnetic [Ni(dmit)2]– Salts

AbstractMagnetic crystals were formed using supramolecular cation structures that consist of (S)‐AIH+(dibenzo[18]crown‐6), (R)‐AIH+(dibenzo[18]crown‐6), or (RS)‐AIH+(dibenzo[18]crown‐6) (AIH+ = indan‐1‐aminium) as the counter cation to [Ni(dmit)2]– ions (dmit2– = 2‐thioxo‐1,3‐dithiole‐4,5‐dithiolate), which bear one S = 1/2 spin. The resulting salts, (S)‐AIH+(dibenzo[18]crown‐6)[Ni(dmit)2] (1), (R)‐AIH+(dibenzo[18]crown‐6)[Ni(dmit)2] (2), and (RS)‐AIH+(dibenzo[18]crown‐6)[Ni(dmit)2] (3), feature supramolecular cations that are formed through the inclusion of the ammonium moiety of AIH+ into the cavity of dibenzo[18]crown‐6 through N–H···O hydrogen bonds. Salts 1, 2, and 3 possess space groups of P21, P21, and P2/m, respectively, and possess similar molecular packings. Chiral cations (S)‐AIH+ (salt 1) and (R)‐AIH+ (salt 2) yielded chiral crystals, whereas racemic (RS)‐AIH+ (salt 3) afforded a racemic crystal with a mirror plane. Within the crystals, alternating layers of [Ni(dmit)2]– ions and(AIH+)(dibenzo[18]crown‐6) cations formed a layered structure along the b axis. Since the 21 axis of salts 1 and 2 were observed along the b axis, effective chiral magnetic interactions between the [Ni(dmit)2]– ions were not observed. In the ac plane, weak interactions among the [Ni(dmit)2]– ions formed a two‐dimensional layer. Temperature‐dependent magnetic susceptibilities of salts 1, 2, and 3 exhibited aCurie–Weiss‐type behavior, which shows weak antiferromagnetic interactions between the [Ni(dmit)2]– ions, with Weiss temperatures of –2.9, –2.9, and –4.2 K, respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Crystal structure and magnetic properties of Gd2([18]crown-6)2(OH)2(CH3CN)2[Ni(dmit)2]4 complex having f- and pi-spins.

Crystal structure and magnetic properties of Gd(2)([18]crown-6)(2)(OH)(2)(CH(3)CN)(2)[Ni(dmit)(2)](2) (dmit(2)(-) = 2-thioxo-1,3-dithiole-4,5-dithiolate) are reported. Gd(3+) ions (S = (7)/(2)) were introduced into the pi-spin network of [Ni(dmit)(2)](-) (S = (1)/(2)) complex as a binuclear supramolecular cation, Gd(2)([18]crown-6)(2)(OH)(2)(CH(3)CN)(2), in which two Gd([18]crown-6) units are bridged with two hydroxide ions. The weak antiferromagnetic interactions between Gd.Gd through hydroxide ions were observed, and [Ni(dmit)(2)](-) formed isolated monomers and dimers in the crystal.

Magnetic Properties of [Ni(dmit)2]- Anions Induced by Flexible Hydrogen-Bonded Supramolecular Cations [(p-Xylylenediammonium)0.5(Crown Ethers)]+

Flexible supramolecular cation structures, [(XyDA)0.5(crown ethers)]+ complexes, were introduced as countercations to [Ni(dmit)2]- anions, which bear an S = 1/2 spin, to form novel magnetic crystals (XyDA = p-xylylenediammonium, dmit2- = 2-thioxo-1,3-dithiole-4,5-dithiolate, and crown ethers = [12]crown-4, [15]crown-5, or [18]crown-6). Sandwich-type [(XyDA)0.5(crown ethers)]+ structures were formed through hydrogen-bonding interactions in the crystals between the ammonium moieties of XyDA and the oxygen atoms of the crown ethers. [12]Crown-4 yielded three types of [(XyDA)0.5([12]crown-4)]+[Ni(dmit)2] polymorphs, whereas two types of [(XyDA)0.5([15]crown-5)]+[Ni(dmit)2] polymorphs were obtained using [15]crown-5. Three types of [(XyDA)0.5(crown ethers)]+ structures were identified for these polymorphs. Since the flexible −CH2−NH3+ moieties connected to benzene plane have rotational freedom, the [(XyDA)0.5(crown ethers)]+ structures varied according to the conformations of the XyDA cation in the crystals. The larger ring size of [18]crown-6 than that of [12]crown-4 and [15]crown-5 reduced the flexibility of the XyDA cation, and provided only one type of crystal. The [Ni(dmit)2]- anion existed as dimer structures, which are in the singlet ground state. The arrangement of the [Ni(dmit)2]- anion in the crystals were depended on the structure of [(XyDA)0.5(crown ethers)]+. Correlation of the absolute values of magnetic exchange energy J to the square of the intradimer transfer integral t2 were confirmed.

Two Polymorphs of (Anilinium)(18-Crown-6)[Ni(dmit) 2]: Structure and Magnetic Properties

Two polymorphs of monovalent [Ni(dmit) 2] − (dmit 2−=2-thioxo-1,3-dithiole-4,5-dithiolate) crystals A and B, (anilinium)(18-crown-6)[Ni(dmit) 2], were prepared, and the structure and magnetic properties were investigated. In these crystals, the [Ni(dmit) 2] − molecules form dimers, which arranged into chains between the supramolecular cation structure (anilinium)(18-crown-6). In crystal A, supramolecular cation formed a regular stack, inducing ladder structure of [Ni(dmit) 2], whose magnetism had been well fitted by spin ladder equation with the spin gap of Δ=190 K. Crystal B is ca. 3% more densely packed compared to crystal A. Due to the dense packing, supramolecular cation stack is distorted, which prevented the intermolecular interaction between [Ni(dmit) 2] − dimers in direction corresponds to the ladder-leg direction in crystal A. Reflecting the [Ni(dmit) 2] − arrangement, crystal B showed a temperature dependence of magnetic susceptibility well reproduced by the singlet–triplet thermal activation model, whose antiferromagnetic exchange interaction (2 J) was 140 K.

Supramolecular cation assemblies of hydrogen-bonded (NH4+/NH2NH3+)(crown ether) in [Ni(dmit)2]-based molecular conductors and magnets.

Hydrogen-bonded supramolecular cation assemblies of (NH4+/NH2-NH3+)(crown ether), where the crown ether is [12]crown-4, [15]crown-5, or [18]crown-6, were incorporated into electrically conducting [Ni(dmit)2] salts (dmit2- = 2-thioxo-1,3-dithiole-4,5-dithiolate). (NH4+)([12]crown-4)[Ni(dmit)2]3(CH3CN)2 had a pyramidal shape, while ionic channels were observed in (NH4+)(0.88)([15]crown-5)[Ni(dmit)(2)]2 and (NH4+)(0.70)([18]crown-6)[Ni(dmit)(2)]2. Both (NH4+)(0.88)([15]crown-5) and (NH4+)(0.70)([18]crown-6) contained regularly spaced [Ni(dmit)(2)] stacks formed by N-H.O hydrogen bonding between the oxygen atoms in crown ethers and the NH4+ ion. NH4+ occurred nonstoichiometrically; there were vacant ionic sites in the ionic channels. The ionic radius of NH4+ is larger than the cavity radius of [15]crown-5 and [18]crown-6. Therefore, NH4+ ions could not pass through the cavity and were distributed randomly in the ionic channels. The static disorder caused the conduction electrons to be randomly localized to the [Ni(dmit)2] stacks. Hydrazinium (NH2-NH3+) formed the supramolecular cations in (NH2-NH3+)([12]crown-4)2[Ni(dmit)2]4 and (NH2-NH3+)2([15]crown-5)3[Ni(dmit)2]6, possessing a sandwich and club-sandwich structure, respectively. To the best of our knowledge, these represent the first hydrazinium-crown ether assemblies to be identified in the solid. In the supramolecular cations, hydrogen bonding was detected between the ammonium or the amino protons of NH2-NH3+ and the oxygen atoms of crown ethers. The sandwich-type cations coexisted with the [Ni(dmit)2] dimer stacks. Although the assemblies were typically semiconducting, ferromagnetic interaction (Weiss temperature = +1 K) was detected in the case of (NH2-NH3+)2([15]crown-5)3[Ni(dmit)2]6. The (NH2-NH3+)0.8([18]crown-6)[Ni(dmit)2]2 and (NH4+)0.76([18]crown-6)[Ni(dmit)2]2 crystals were isomorphous. The large and flexible [18]crown-6 allowed for maintaining the same ionic channel structure through replacement of the NH4+ cation by NH2-NH3+.

Formation of a molecular spin ladder induced by a supramolecular cation structure

A novel molecular spin ladder structure of a nickel dithiolate complex has been constructed using a supramolecular cation composed of anilinium and 18-crown-6.

Crystal Structure and Magnestism of [Ni(dmit) 2 ] − Salts With Supramolecular Cations of M + (15-Crown-5)

The crystals M + (15-crown-5) 2 [Ni(dmit) 2 ](M + = K + Rb + ( 2 ) and NH + 4 ( 3 )) were prepared. In the crystal, M + and 15-crown-5 formed a barrel-shape supramolecular cation structure, which filled the space between the [Ni(dmit) 2 ] − formed the φ - φ dimers which were connected through the side-by-side S ∼ S contacts. The interactions between [Ni(dmit) 2 ] − within the dimer were not strong enough and the crystals showed Curie-Weiss magnetic susceptibility with the Weiss temperature θ of −3.8, −2.8 and −3.2 K for the salts 1 , 2 and 3 , respectively.

Unexpected solid-solid reaction upon preparation of KBr pellets and its exploitation in supramolecular cation complexation.

Pressing solid [CoIII(eta 5-C5H4COOH)(eta 5-C5H4COO)] with KBr to prepare samples for IR spectroscopy leads to a profound solid state rearrangement with formation of the supramolecular complex [CoIII(eta 5-C5H4COOH)(eta 5-C5H4COO)]2.K+Br-, which can also be obtained from solution crystallization. Similar solid-solid supramolecular complexation has been observed with K[PF6] and [NH4][PF6].

Structures of flexible supramolecular cations (1,4-cyclohexanediammonium 2+)(crown ethers) 2 in [Ni(dmit) 2] − salts

Supramolecular dication structures, ( CHDA 2+)(crown ethers) and ( CHDMA 2+)(crown ethers) complexes, were introduced as counter cations to [Ni(dmit) 2] − anions (S=1/2 spin) ( CHDA 2+= trans-1,4-cyclohexanediammonium; CHDMA 2+=1,4-bis(methylammonium)cyclohexane; dmit 2−=2-thioxo-1,3-dithiole-4,5-dithiolate; crown ethers=[12]crown-4, [15]crown-5, or [18]crown-6). The cyclohexane rings, with the –NH 3 + or –CH 2–NH 3 + substituents at trans-1,4-positions, arrange into the crown ethers complexes within the [Ni(dmit) 2] − salts. The cyclohexane rings adopt chair conformations, resulting in sandwich-type ( CHDA 2+ or CHDMA 2+)(crown ethers) 2 structures, through N–H … O hydrogen-bonding interactions within the crystals between the ammonium moieties of cations (–NH 3 + or –CH 2–NH 3 +) and the oxygen atoms of the crown ethers. Formations of π–π dimer structures of [Ni(dmit) 2] − anions were observed in all salts. The selections of the dication structures ( CHDA 2+ or CHDMA 2+) and the crown ethers, due to the various ring sizes, can influence the intra and interdimer interactions of the [Ni(dmit) 2] − anions in the crystals.

Ionic Channel Structures in [(M+)x([18]crown-6)][Ni(dmit)2]2 Molecular Conductors

The [(M+)x[18]crown-6)] supramolecular cations (SC+), in which M+ and [18]crown-6 are alkali metal ions (M+ = Li+, Na+, and Cs+) and 1,4,7,10,13,16-hexaoxacyclooctadecane, respectively, form ionic channel structures through the regular stacks of [18]crown-6 in [Ni(dmit)2]-based molecular conductors (dmit2+ = 2-thioxo-1,3-dithiole-4,5-dithiolate). In addition to the [Ni(dmit)2] salts that have the ionic channel structures (these salts are abbreviated as type I salts), Li+ and Na+ form dimerized [(M+)2([18]crown-6)2] units in the crystals (type II salts). The K+ and Rb+ are coordinated tightly into the [18]crown-6 cavity to form typical disk-shape SC+ units in the corresponding [Ni(dmit)2] salts (type III salts). The type I, II, and III salts have typical stoichiometries of [(M+)x([18]crown-6)][Ni(dmit)2]2, [(M+)([18]crown-6)(H2O)x(CH3CN)(1.5 - x)][Ni(dmit)2]3 (x = 1 for Li+ or 0.5 for Na+), and [M+([18]crown-6)][Ni(dmit)2]3, respectively: the salts of the same type are isostructural. In agreement with the trimer structures of [Ni(dmit)2] in the type II and III salts, they exhibit semiconducting behavior with electrical conductivities at 300 K (sigma(300 K)) of 0.01-0.1 S cm(-1). Type I salts contain a regular stack of partially oxidized [Ni(dmit)2] units, which form a quasi one-dimensional metallic band within the tight-binding approximation regime. The electrical conductivities at 300 K are 10-30 S cm(-1), and an almost temperature-independent conductivity was observed at higher temperatures. However, the one-dimensional electronic structures in these salts are strongly influenced by the static and dynamic structures of the coexisting ionic channel. The Na+ salt is a semiconductor, whose magnetic behavior is described by the disordered one-dimensional antiferromagnetic chain. On the other hand, the Cs+ salt is a exhibits metallic properties with 2 kF instability at room temperature. The Li+ salt shows a gradual transition from the high-temperature metallic phase to the low-temperature one-dimensional antiferromagnetic semiconductor phase, which was associated with the freezing of Li+ motion at lower temperatures. The preferential crystallization of type I salts was possible by controlling the equilibrium constant (Kc) of the complex formation between M+ ions and the [18]crown-6 molecule. The ionic channel structures were obtained when the KC was low in the electrocrystallization solution, while type II or III salts were formed in the high Kc region.

Ni(dmit) 2] − salt of a supramolecular cation, Sc 3+(12-crown-4) 2

We controlled [Ni(dmit) 2 ] - (S = 1/2) arrangements using a supramolecular cation (SC) of 12-crown-4 including trivalent Sc 3+ ion. The new crystal, Se 3+ (12-crown-4) 2 [Ni(dmit) 2 ] 3 (CH 3 CN) 4 , was composed of [Ni(dmit) 2 ] - trimer and sandwich-type Sc 3+ (12-crown-4) 2 . The magnetic susceptibility per trimer unit was 0.35 emu.K. mol -1 , which showed Curie paramagnetic temperature dependence. The details of the structure and magnetic behavior are discussed in comparison with monovalent and divalent salts, Rb + (DA18-crown-6)[Ni(dmit) 2 ] and Ca 2+ (DA18-crown-6)[Ni(dmit) 2 ] 2 (CH 3 CN) 2 (DA18-crown-6 = 1,10-diaza-18-crown-6).

Diversity in the ½ spin arrangement of [Ni(dmit)2]– anions in divalent Ca2+(crown ether) supramolecular cation salts

Calcium ion (Ca2+) and crown ethers, 12-crown-4, 15-crown-5, 1-aza-18-crown-6 (A18-crown-6) and 1,10-diaza-18-crown-6 (DA18-crown-6), were assembled into divalent supramolecular cation (SC2+) structures in the monovalent [Ni(dmit)2]− salts (dmit2− = 2-thioxo-1,3-dithiole-4,5-dithiolate), which regulate the arrangement of the [Ni(dmit)2]− anions in the crystal. The divalent SC2+–[Ni(dmit)2]− system showed a larger diversity of crystal structures compared with the monovalent SC+ system. Peculiar magnetic behavior was observed depending on the arrangement of the S = ½ spins on the [Ni(dmit)2]− anions. Single crystals of Ca2+(12-crown-4)2[Ni(dmit)2]2 (1) and Ca2+(15-crown-5)2[Ni(dmit)2]2(CH3CN)0.7 (2) had a typical sandwich-type Ca2+(crown ether)2 structure, which included the formation of π–π dimers and monomers of [Ni(dmit)2]− anions in the crystal. The temperature-dependent magnetic susceptibility (χm) of salt 1 showed a magnetic transition at 190 K, at which temperature the spins on each [Ni(dmit)2]− dimer formed a singlet pair. On the other hand, the magnetic behavior of salt 2 obeyed the Curie–Weiss law. The Ca2+ ions in the isostructural single crystals of Ca2+(A18-crown-6)[Ni(dmit)2]2(CH3CN)2 (3) and Ca2+(DA18-crown-6)[Ni(dmit)2]2(CH3CN)2 (4) were completely included into the 18-crown-6 cavity, and further interacted with two CH3CN molecules from the axial position. The resultant Ca2+(18-crown-6)(CH3CN)2 cations induced the formation of uniform zig-zag chains of the [Ni(dmit)2]− anions, the magnetic susceptibility of which were explained by a one-dimensional Heisenberg antiferromagnetic linear chain. The magnetism of these salts was discussed in terms of the intermolecular transfer integral t.

Synthesis and characterization of silicon and cobalt substituted mesoporous aluminophosphates

A variety of silicon and cobalt substituted mesoporous aluminophosphate materials with different incorporated contents were prepared in the presence of supramolecular template alkyltrimethylammonium cations. The characterization of these solid products by various techniques such as XRD, N 2 adsorption, DRS, and 27Al, 31P MAS NMR spectroscopies has been carried out to understand the local atomic arrangements and the coordination environment. Si and Co can be introduced into the framework of aluminophosphate-based mesoporous materials, respectively. About 41 wt.% of the templating surfactant can be extracted by acid alcohol, however this treatment can not efficiently enhance the thermal stability of these products.

M+(12-crown-4) supramolecular cations (M+ = Na+, K+, Rb+, and NH4+) within Ni(2-thioxo-1,3-dithiole-4,5-dithiolate)2 molecular conductor.

Monovalent cations (M+ = Na+, K+, Rb+, and NH4+) and 12-crown-4 were assembled to new supramolecular cation (SC+) structures of the M+(12-crown-4)n (n = 1 and 2), which were incorporated into the electrically conducting Ni(dmit)2 salts (dmit = 2-thioxo-1,3-dithiole-4,5-dithiolate). The Na+, K+, and Rb+ salts are isostructural with a stoichiometry of the M+(12-crown-4)2[Ni(dmit)2]4, while the NH4+ salt has a stoichiometry of NH4+(12-crown-4)[Ni(dmit)2]3(CH3CN)2. The electrical conductivities of the Na+, K+, Rb+, and NH4+ salts at room temperature are 7.87, 4.46, 0.78, and 0.14 S cm-1, respectively, with a semiconducting temperature dependence. The SC+ structures of the Na+, K+, and Rb+ salts have an ion-capturing sandwich-type cavity of M+(12-crown-4)2, in which the M+ ion is coordinated by eight oxygen atoms of the two 12-crown-4 molecules. On the other hand, the NH4+ ion is coordinated by four oxygen atoms of the 12-crown-4 molecule. Judging from the M(+)-O distances, thermal parameters of oxygen atoms, and vibration spectra, the thermal fluctuation of the Na+(12-crown-4)2 structure is larger than those of K+(12-crown-4)2 and Rb+(12-crown-4)2. The SC+ unit with the larger alkali metal cation gave a stress to the Ni(dmit)2 column, and the SC+ structure changed the pi-pi overlap mode and electrically conducting behavior.

M+ (Crown Ether) Supramolecular Cations (M+ = K+, Rb+, NH4 +) for Controlling Magnetic Properties of Monovalent [Ni(dmit)2]− Salts

Supramolecular cations (SC+) of K+, Rb+, or NH4 +(crown ether) were incorporated into the monovalent [Ni(dmit)2]− salts. The K+ and Rb+(DA18-crown-6) units had a planar disk-shaped SC+ structure, while the [NH4 +(15-crown-5)2]2 was the barrel type SC+ structure. The [Ni(dmit)2]− arrangement and magnetic properties of these salts depended on the coordination properties in the cation structures.

One-dimensional antiferromagnetic chain in [Ni(dmit)2]- salts of [K+ or Rb+(4,13-diaza-18-crown-6)] supramolecular cation.

Mixed-stack structures of monovalent [Ni(dmit)2]- and planar M+(4,13-diaza-18-crown-6) (M+ = K+ or Rb+) supramolecular cation were obtained in the isostructural M+(4,13-diaza-18-crown-6)[Ni(dmit)2] salts. The mixed-stack structure decreases the effective π−π overlap of [Ni(dmit)2]- molecules, which results in the one-dimensional Heisenberg antiferromagnetic linear chain of S = 1/2 spins within the crystal.