Li2B12C2 und LiB13C2: farblose borreiche Boridcarbide des Lithiums

Vojteer, Natascha; Hillebrecht, Harald

doi:10.1002/ange.200502325

Cited by 19 publications

(41 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The icosahedron is the most common structural unit in the chemistry of boron, and is also found in borides and boride carbides of the main group elements whose crystal structures cannot be directly derived from those of the (postulated) boron allotropes. This is exemplified by BeB 3 [244,245] and the new lithium compounds, Li 2 B 12 C 2 (1), LiB 13 C 2 (2), [137] Li 2 B 12 Si 2 (3), [140] and LiB 12 PC (4), [246] of which light-green (1), colorless (2, 4), or yellow (3) single crystals have been synthesized from the elements at temperatures of 1570 K and 1770 K in tin melts. The compounds crystallize orthorhombically (space group Amm2, no.…”

Section: Boron Compounds With a T-imentioning

confidence: 99%

“…Despite this, this synthesis route has proved itself: Li 2 B 12 C 2 , MgB 12 , Li 2 B 12 Si 2 , MgB 12 Si 2 , and MgB 12 C 2 are some examples of single-phase, highly pure, single-crystal boron compounds which have recently been obtained in this way. [136][137][138][139][140] There have been occasional reports of the use of chemical transport reactions and chemical vapor deposition (CVD) techniques to synthesize boron and borides. [141] These methods, however, have not so far proved themselves for boronrich compounds to the extent that it seems necessary to discuss them here in detail.…”

Section: Synthesismentioning

confidence: 99%

“…The example of the alkaline-earth hexaborides has shown that quite a precise determination of the composition of boron-rich borides is possible. [142] Energyand wavelength-dispersive X-ray spectroscopy (EDS, WDS) have also been employed [136][137][138][139][140]143] to quantify the components of borides. Careful handling and preparation of the samples as well as the employment of suitable, well-defined standards are essential.…”

Section: Characterization and Analysismentioning

confidence: 99%

See 2 more Smart Citations

Boron: Elementary Challenge for Experimenters and Theoreticians

Albert¹,

Hillebrecht²

2009

Angew Chem Int Ed

Self Cite

580

436

View full text Add to dashboard Cite

Many of the fundamental questions regarding the solid-state chemistry of boron are still unsolved, more than 200 years after its discovery. Recently, theoretical work on the existence and stability of known and new modifications of the element combined with high-pressure and high-temperature experiments have revealed new aspects. A lot has also happened over the last few years in the field of reactions between boron and main group elements. Binary compounds such as B(6)O, MgB(2), LiB(1-x), Na(3)B(20), and CaB(6) have caused much excitement, but the electron-precise, colorless boride carbides Li(2)B(12)C(2), LiB(13)C(2), and MgB(12)C(2) as well as the graphite analogue BeB(2)C(2) also deserve special attention. Physical properties such as hardness, superconductivity, neutron scattering length, and thermoelectricity have also made boron-rich compounds attractive to materials research and for applications. The greatest challenges to boron chemistry, however, are still the synthesis of monophasic products in macroscopic quantities and in the form of single crystals, the unequivocal identification and determination of crystal structures, and a thorough understanding of their electronic situation. Linked polyhedra are the dominating structural elements of the boron-rich compounds of the main group elements. In many cases, their structures can be derived from those that have been assigned to modifications of the element. Again, even these require a critical revision and discussion.

show abstract

Section: Boron Compounds With a T-imentioning

confidence: 99%

Section: Synthesismentioning

confidence: 99%

Section: Characterization and Analysismentioning

confidence: 99%

See 1 more Smart Citation

Boron: Elementary Challenge for Experimenters and Theoreticians

Albert¹,

Hillebrecht²

2009

Angew Chem Int Ed

Self Cite

580

436

View full text Add to dashboard Cite

show abstract

“…Li cations occupy voids of the framework (Figure 2). LiB 12 PC is a new variant of the MgB 7 type, [21,22] like LiB 13 C 2 , [9] orthorhombic MgB 12 C 2 , [12] Na 2 B 29 , [24] MAlB 14 (M = Li, Na, Mg, rare earth elements) [25] and ScB 13 C. [23] The B 12 icosahedra are arranged in a nearly hexagonal primitive packing ( Figure 3). Every icosahedron has 12 exohedral two-electron two-centre (2e-2c) bonds, six to neighbouring icosahedra and six to the disordered PÀC units.…”

Section: Introductionmentioning

confidence: 99%

“…[5] No other boron-rich boride containing phosphorus has been synthesised until now. [8] In the course of our research on boron-rich lithium and magnesium borides, we found several new compounds including the first colourless and electron-precise boron-rich borides Li 2 B 12 C 2 , [9] LiB 13 C 2 , [9] MgB 12 Si 2 , [10] Li 2 B 12 Si 2 , [11] MgB 12 C 2 , [12] Mg 2 B 24 C, [13] and Mg 3 B 50 C 8 . [14] The crystal structures of these compounds are remarkably simple.…”

Section: Introductionmentioning

confidence: 99%

LiB₁₂PC, the First Boron‐Rich Metal Boride with Phosphorus—Synthesis, Crystal Structure, Hardness, Spectroscopic Investigations

Vojteer

Sagawe

Stauffer

et al. 2011

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

We present synthesis, crystal structure, hardness, and IR/Raman and UV/Vis spectra of a new compound with the mean composition LiB(12)PC. Transparent single crystals were synthesised from Ga, Li, B, red phosphorus and C at 1500 °C in boron nitride crucibles welded in Ta ampoules. Depending on the type of boron used for the synthesis we obtained colourless, brown and red single crystals with slightly different P/C ratios. Colourless LiB(12)PC crystallizes orthorhombic in the space group Imma (No. 74) with a=10.188(2) Å, b=5.7689(11) Å, c=8.127(2) Å and Z=4. Brown LiB(12)P(0.89)C(1.11) is very similar, but with a lower P content. Red single crystals of LiB(12)P(1.13)C(0.87) have a larger unit cell with a=10.4097(18) Å, b=5.9029(7) Å, c=8.2044(12) Å. EDX measurements confirm that the red crystals contain more phosphorus than the other ones. The crystal structure is characterized by a covalent network of B(12) icosahedra connected by exohedral B-B bonds and P-P, P-C or C-C units. Li atoms are located in interstitials. The structure is closely related to MgB(7), LiB(13)C(2) and ScB(13)C. LiB(12)PC fulfils the electron counting rules of Wade and also Longuet-Higgins. Measurements of Vickers micro-hardness (H(V)=27 GPa) revealed that LiB(12)PC is a hard material. The optical band gaps obtained from UV/Vis spectra match the colours of the crystals. Furthermore we report on the IR and Raman spectra.

show abstract

Bor – elementare Herausforderung für Experimentatoren und Theoretiker

Albert

Hillebrecht

2009

Angewandte Chemie

Self Cite

View full text Add to dashboard Cite

Auch mehr als zweihundert Jahre nach der Entdeckung des Elementes Bor gibt es auf viele grundlegende Fragen in der Festkörperchemie von Bor noch keine eindeutigen Antworten. In jüngster Zeit zeigten theoretische Arbeiten zur Stabilität und Existenz bekannter und neuer Modifikationen des Elements in Verbindung mit Hochdruck‐ und Hochtemperaturexperimenten neue Aspekte. Auch auf dem Gebiet der Reaktionen von Bor mit Hauptgruppenelementen hat sich in den letzten Jahren viel getan. Aufsehen haben binäre Verbindungen wie B6O, MgB2, LiB1−x, Na3B20 oder CaB6 erregt, aber auch die elektronenpräzisen, farblosen Boridcarbide Li2B12C2, LiB13C2 und MgB12C2 sowie Graphit‐analoges BeB2C2 verdienen besonderes Augenmerk. Physikalische Eigenschaften wie Härte, Supraleitfähigkeit, Neutroneneinfangquerschnitt und Thermoelektrizität machen borreiche Verbindungen auch für Materialforschung und Anwendung attraktiv. Die größten wissenschaftlichen Herausforderungen bestehen jedoch weiterhin in der Synthese einphasiger Produkte in makroskopischen Mengen und in Form von Einkristallen, in der zweifelsfreien Identifizierung und Bestimmung von Zusammensetzung und Kristallstruktur sowie im Verständnis der elektronischen Situation. Verknüpfte Polyeder sind das dominierende Strukturelement in borreichen Verbindungen der Hauptgruppenelemente. In vielen Fällen leiten sich deren Strukturen von denen ab, die den Elementmodifikationen zugeschrieben werden. Auch diese bedürfen allerdings einer neuen, kritischen Durchsicht und Diskussion.

show abstract

Li₂B₁₂C₂ und LiB₁₃C₂: farblose borreiche Boridcarbide des Lithiums

Cited by 19 publications

References 39 publications

Boron: Elementary Challenge for Experimenters and Theoreticians

Boron: Elementary Challenge for Experimenters and Theoreticians

LiB₁₂PC, the First Boron‐Rich Metal Boride with Phosphorus—Synthesis, Crystal Structure, Hardness, Spectroscopic Investigations

Bor – elementare Herausforderung für Experimentatoren und Theoretiker

Contact Info

Product

Resources

About

Li2B12C2 und LiB13C2: farblose borreiche Boridcarbide des Lithiums

Cited by 19 publications

References 39 publications

Boron: Elementary Challenge for Experimenters and Theoreticians

Boron: Elementary Challenge for Experimenters and Theoreticians

LiB12PC, the First Boron‐Rich Metal Boride with Phosphorus—Synthesis, Crystal Structure, Hardness, Spectroscopic Investigations

Bor – elementare Herausforderung für Experimentatoren und Theoretiker

Contact Info

Product

Resources

About

Li₂B₁₂C₂ und LiB₁₃C₂: farblose borreiche Boridcarbide des Lithiums

LiB₁₂PC, the First Boron‐Rich Metal Boride with Phosphorus—Synthesis, Crystal Structure, Hardness, Spectroscopic Investigations