RESUMEN
The existence of [µ-HSi4 ]3- in liquid ammonia solutions is confirmed by 1 H and 29 Siâ NMR experiments. Both NMR and quantum chemical calculations reveal that the H atom bridges two Si atoms of the [Si4 ]4- cluster, contrary to the expectation that it is located at one vertex Si of the tetrahedron. The calculations also indicate that in the formation of [µ-HSi4 ]3- , protonation is driven by a high charge density and an increase of electron delocalization compared to [Si4 ]4- . Additionally, [Si5 ]2- was detected for the first time and characterized by NMR. Calculations show that it is resistant to protonation, owing to a strong charge delocalization, which is significantly reduced upon protonation. Thus, our methods reveal three silicides in liquid ammonia: unprotonated [Si5 ]2- , terminally protonated [HSi9 ]3- , and bridge-protonated [µ-HSi4 ]3- . The protonation trend can be roughly predicted by the difference in charge delocalization between the parent compound and the product, which can be finely tuned by the presence of counter ions in solution.
RESUMEN
We report on the first unambiguous detection of the elusive [HSi9 ]3- anion in solutions of liquid ammonia by various 29 Si and 1 Hâ NMR experiments including chemical exchange saturation transfer (CEST). The characteristic multiplicity patterns of both the 29 Si and 1 H resonances together with CEST and a partially reduced 1 H,29 Si coupling constant indicate the presence of a highly dynamic Si8 entity and a Si-H moiety with slow proton hopping. Theoretical calculations corroborate both reorganization of Si8 on the picosecond timescale via low vibrational modes and proton hopping. In addition, in a single-crystal X-ray study of (K(DB[18]crown-6))(K([2.2.2]crypt))2 [HSi9 ]â 8.5 NH3 , the Hâ atom was unequivocally localized at one vertex of the basal square of the monocapped square-antiprismatic cluster. Thus experimental studies and theoretical considerations provide unprecedented insight into both the structure and the dynamic behavior of these cluster anions, which hitherto had been considered to be rigid.
RESUMEN
Homoatomic polyanions of post-transition main-group metals, namely, Zintl anions, are precast in analogous Zintl phases and can react in solution to form new materials. Despite comprehensible reaction approaches, the formed products cannot be planned in advance, as hitherto undetected and therefore disregarded side reactions take place. The outcomes and interpretations of the reactions of Zintl anions are so far based mainly on crystal structures, which only allow characterization of the product that has the lowest solubility. Here we present the results of our investigation of the stability of highly charged tin Zintl anions in liquid ammonia, which is not exclusively based on solution effects but also on the oxidative influence of the solvent. This allows for a deeper understanding of the ongoing processes in solution and opens doors to the directed synthesis of transition metal complexes of Sn4 (4-) , here shown by its reactivity towards MesCu.
RESUMEN
The title compound, [Pt(NH3)4]Cl2·4NH3, was crystallized in liquid ammonia from the salt PtCl2. The platinum cation is coordinated by four ammonia mol-ecules, forming a square-planar complex. The chloride anions are surrounded by nine ammonia mol-ecules, either bound within the platinum complex or solvent mol-ecules. The solvent ammonia mol-ecules are packed in such a way that an extended network of N-Hâ¯N and N-Hâ¯Cl hydrogen bonds is formed. The structure is isotypic with [Pd(NH3)4]Cl2·4NH3 [Grassl & Korber (2014). Acta Cryst. E70, i32].
RESUMEN
The title compound, [Pd(NH3)4]Cl2·4NH3, was crystallized in liquid ammonia from the salt Pd(en)Cl2 (en is ethylenediamine) and is isotypic with [Pt(NH3)4]Cl2·4NH3 [Grassl & Korber (2014 â¶). Acta Cryst. E70, i31]. The Pd(2+) cation is coordinated by four ammonia mol-ecules, exhibiting a square-planar geometry. The chloride anions are surrounded by nine ammonia mol-ecules. These are either bound in the palladium complex or solvent mol-ecules. The packing of the ammonia solvent mol-ecules enables the formation of an extended network of N-Hâ¯N and N-Hâ¯Cl inter-actions with nearly ideal hydrogen-bonding geometry.
RESUMEN
The title compound, penta-caesium nona-stannide hydroxide tetra-ammonia, crystallized from a solution of CsSnBi in liquid ammonia. The Sn9 (4-) unit forms a monocapped quadratic anti-prism. The hydroxide ion is surrounded by five caesium cations, which form a distorted quadratic pyramidal polyhedron. A three-dimensional network is formed by Cs-Sn [3.8881â (7)â Å to 4.5284â (7)â Å] and Cs-NH3 [3.276â (7)-3.636â (7)â Å] contacts.
RESUMEN
Red crystals of the title salt, [K(C12H24O6)][Sb(C6H5)2], were obtained by the reaction of SbPh3, KSnBi and 18-crown-6 in liquid ammonia. The asymmetric unit contains one half of a [K(18-crown-6)](+) cation and one half of an SbPh2 (-) anion, with the central element lying on a twofold axis and a centre of inversion, respectively. In the crystal structure, the sequestered potassium cations show weak inter-actions with the π-electrons of the phenyl groups of the SbPh2 (-) anion [shortest Kâ¯C distances = 3.190â (2) and 3.441â (2)â Å], leading to one-dimensional strands along the crystallographic c axis. These strands are aligned in a pseudo-hexa-gonal packing perpendicular to the ab plane.
RESUMEN
Two new trigonal and tetra-gonal polymorphs of the title compound, iodido-tris-(tetra-hydro-furan-κO)lithium, are presented, which both include the isolated ion pair Li(THF)3 (+)·I(-). One Li-I ion contact and three tetra-hydro-furan (THF) mol-ecules complete the tetra-hedral coordination of the lithium cation. The three-dimensional arrangement in the two polymorphs differs notably. In the trigonal structure, the ion pair is located on a threefold rotation axis of space group P-3 and only one THF mol-ecule is present in the asymmetric unit. In the crystal, strands of ion pairs parallel to [001] are observed with an eclipsed conformation of the THF mol-ecules relative to the Liâ¯I axis of two adjacent ion pairs. In contrast, the tetra-gonal polymorph shows a much larger unit cell in which all atoms are located on general positions of the space group I41 cd. The resulting three-dimensional arrangement shows helical chains of ion pairs parallel to [001]. Apart from van der Waals contacts, no remarkable inter-molecular forces are present between the isolated ion pairs in both structures.
RESUMEN
The title compound, [Li(NH(3))(4)](+)[Li(NH(3))(3)S(3)](-), an ammo-niate of the previously unknown lithium tris-ulfide, was obtained from the reaction of lithium and sulfur in liquid ammonia. The asymmetric unit consists of two crystallographically independent formula units. The [Li(NH(3))(4)](+) cations are close to regular LiN(4) tetra-hedra. The anions contain LiSN(3) tetra-hedra; the S-S-S bond angles are 110.43â (5) and 109.53â (5)°. In the crystal, the components are linked by multiple N-Hâ¯S hydrogen bonds. A weak N-Hâ¯N hydrogen bond is also present.
RESUMEN
The title compound, C(2)H(2)·C(12)H(24)O(6)·2NH(3), was formed by co-crystallization of 18-crown-6 and acetyl-ene in liquid ammonia. The 18-crown-6 mol-ecule has threefold rotoinversion symmetry. The acteylene mol-ecule lies on the threefold axis and the whole mol-ecule is generated by an inversion center. The two ammonia mol-ecules are also located on the threefold axis and are related by inversion symmetry. In the crystal, the ammonia mol-ecules are located below and above the crown ether plane and are connected by inter-molecular N-Hâ¯O hydrogen bonds. The acetyl-ene mol-ecules are additionally linked by weak C-Hâ¯N inter-actions into chains that propagate in the direction of the crystallographic c axis. The 18-crown-6 mol-ecule [occupancy ratio 0.830â (4):0.170â (4)] is disordered and was refined using a split model.
RESUMEN
Carbon anions in solution: C(2)(2-) dumbbells are well-known in solid-state compounds. The crystallization of the title compounds now shows that acetylide ions are existent in solution and therefore chemistry with small dissolved carbon anions may be within reach.
RESUMEN
The crystal structure of the title compound, poly[[(4,7,13,16,21,24-hexa-oxa-1,10-diaza-bicyclo-[8.8.8]hexa-cosa-ne)rubidium] [[(1,4,7,10,13,16-hexa-oxacyclo-octa-deca-ne)rubidium]di-µ-rubidium-µ-nona-stannide] penta-ammonia], {[Rb(C(18)H(36)N(2)O(6))][Rb(3)Sn(9)(C(12)H(24)O(6))C(12)H(24)O(6))]·5NH(3)}(n) represents the first ammoniate of a Zintl anion together with two different chelating substances, namely 18-crown-6 and [2.2.2]-cryptand. The involvement of these large mol-ecules in the crystal structure of [Rb(18-crown-6)][Rb([2.2.2]-cryptand)]Rb(2)Sn(9)·5NH(3) leads to the formation of a new structural motif, namely one-dimensionally extended double strands running parallel to [100] and built by Sn(9) (4-) cages and Rb(+) cations. The double strands are shielded by 18-crown-6 and [2.2.2]-cryptand. The cations are additionally coordin-ated by ammonia mol-ecules. One of the four independent Rb(+) cations is disordered over two sets of sites in a 0.74â (2):0.26â (2) ratio.
RESUMEN
The crystal structure of the title compound, [Rb(C(12)H(24)O(6))](3)[Sb(7)]·4NH(3), fills the gap between the already known Zintl anion ammoniates {[Cs(18-crown-6)](3)Sb(7)}(2)·9NH(3) [Wiesler (2007 â¶). Dissertation, Universität Regensburg, Germany] and [K(18-crown-6)](3)Sb(7)·4NH(3) [Hanauer (2007 â¶). Dissertation, Universität Regensburg, Germany]. As in the two known compounds, the anti-mony cage anion in this crystal structure is coordinated by three alkali cations. The coordination spheres of each of the cations are saturated by 18-crown-6 mol-ecules. The ammonia mol-ecules of crystallization are situated between the crown ethers. The neutral, mol-ecular [Rb(18-crown-6)](3)Sb(7) units are inter-connected by multiple dipole-dipole interactions between ammonia and 18-crown-6.
RESUMEN
The incongruous solvation of polyphosphides and phosphanes or the direct reduction of white phosphorus in liquid ammonia leads to the hydrogen polyphosphides catena-dihydrogen triphosphide, P(3)H(2)(3-), and catena-trihydrogen triphosphide, P(3)H(3)(2-), in the crystalline compounds K(3)(P(3)H(2)).2.3NH(3) (1), Rb(3)(P(3)H(2)).NH(3) (2), [Rb(18-crown-6)](2)(P(3)H(3)).7.5NH(3) (3), and [Cs(18-crown-6)](2)(P(3)H(3)).7NH(3) (4).
RESUMEN
A different drummer: The existence of endohedral germanium clusters was predicted earlier by gas-phase experiments. The [Co@Ge(10)](3-) anion now synthesized is surprising, as it breaks with a long line of exclusively deltahedral structures found in the past. Instead, it has a regular pentagonal-prismatic structure (see picture; Co gray, Ge red).
RESUMEN
A tetragonal distortion of the long-time known NaTl structure at 298 K was observed in different experimental setups, including Zintl's original procedure of reducing Tl(I)-iodide by sodium liquid ammonia solutions. The powder diffraction pattern obtained by the high temperature synthesis using classical solid-state techniques allowed a model-independent unambiguous structure solution and refinement of tetragonal distorted NaTl (Rp = 0.0179, wRp = 0.0246, R = 0.0477, wR = 0.0527, GooF = 1.24).
RESUMEN
The title compound, Rb+·H3CN2O-, has been crystallized in liquid ammonia as a reaction product of the reductive ammonolysis of the natural compound streptozocin. Elemental rubidium was used as reduction agent as it is soluble in liquid ammonia, forming a blue solution. Reductive bond cleavage in biogenic materials under kinetically controlled conditions offers a new approach to gain access to sustainably produced raw materials. The anion is nearly planar [dihedral angle O-N-N-C = -0.4â (2)°]. The Rb+ cation has a coordination number of seven, and coordinates to five anions. One anion is bound via both its N atoms, one by both O and N, two anions are bound by only their O atoms, and the last is bound via the N atom adjacent to the methyl group. The diazo-tate anions are bridged by cations and do not exhibit any direct contacts with each other. The cations form corrugated layers that propagate in the (-101) plane.
RESUMEN
The title compound, Rb2O2·2NH3, has been obtained as a reaction product of rubidium metal dissolved in liquid ammonia and glucuronic acid. As a result of the low-temperature crystallization, a disolvate was formed. To our knowledge, only one other solvate of an alkali metal peroxide is known: Na2O2·8H2O has been reported by Grehl et al. [Acta Cryst. (1995), C51, 1038-1040]. We determined the peroxide bond length to be 1.530â (11)â Å, which is in accordance with the length reported by Bremm & Jansen [Z. Anorg. Allg. Chem. (1992), 610, 64-66]. One of the ammonia solvate molecules is disordered relative to a mirror plane, with 0.5 occupancy for the corresponding nitrogen atom.
RESUMEN
The solid state NMR spectra of the binary alkali hexaphosphides Rb4P6 and Cs4P6 unambiguously show the P(6)4- anion not to be aromatic.