Si-Si Bond Length Research Articles

Applying the first principle to study the structure, electrical and magnetic properties of ASiNRs-doped Neodymium

In this project, we investigated and investigated the optimal sites in the chemisorption of Neodymium (Nd) on armchair silicene nanoribbons (ASiNRs) to learn about the geometrical and electronic properties of the structures by applying these properties with first principle math. The survey has three steps. The first was to change the top, valley, bridge, and hollow positions to find optimazed positionThe results show that the Bridge position has the lowest absorbed energy value of -2.6eV, has the most stable structure, with the strongest magnetic moment of 4.68 μB, and a buckl degree of 0.69 Å; The Si-Si-Si bond angle at this time is 115053’ almost like the pristine case. The second was to change the Si-Si bondlength of ASiNRs the same purpose. Finally, we survey the distance from Nd atom to pristine adsorbent surface was decreased. The calculation results show that the valley position is the most ideal location, corresponding to the bond length of 2.26 Å and the optimal height of 2.11 Å resulting in a single material adsorption system for the new materials, different from other positions with bandgap changed. This result shows that the absorption method between metals and pristine semiconductor ASiNRs has opened up a very good direction, contributing to enriching the source of materials applied to the field of manufacturing electronic, optoelectronic, and spintronic components in the future.

STUDYING THE STRUCTURAL, ELECTRICAL, AND MAGNETIC CHARACTERISTICS OF ASiNRS-DOPED NEODYMIUM USING THE FIRST PRINCIPLE

There have been many applied studies on Nd in medicine, cooling techniques due to large amplitude changes in specific heat capacity, making glass pigments, making laser materials, and many other fields. However, there have been no specific studies on the structural and electronic properties related to the band gap. In this study, we investigated the optimization of Nd adsorption on Armchair nanoribbon silicene substrate. The research was carried out in three steps. The first step is to change the Nd atom through the four positions (top, valley, hollow, and bridge) to determine the optimal position. As a result, the bridge site has a magnetic moment of 4.68 µB and a locking degree of 0.69 Ǻ, has the lowest absorbed energy value of -2.6 eV, and has the most stable structure. Second step, we varied the Si-Si bond length of silicene for the same target, resulting in choosing the optimal bond length of 2.27 Ǻ. Finally, we consider the distance between the Nd atom and the silicene surface and determine that with the same bond length 2.27 Ǻ, the result obtained at a height of 2.11 Ǻ occurs most optimally. This result proves that silicene-doped Nd is very promising as a material for making visible sensors and spin motors in the future.

Structural, Electronic and Magnetic Properties of Silicene Functionalized with 4d TM Atoms

The experimental realization of silicene has ignited a great deal of interest in researching its properties for utilization in device applications. Silicene is composed of a lattice of silicon. As a result, it can be integrated with contemporary circuitry structures, which are predominantly silicon-based. Therefore, investigating its characteristics, especially those of the bandgap, is pivotal. In the present work, the density functional theory approach is employed to examine the structural, electronic and magnetic characteristics of free-standing silicene doped with 4d Transition Metal (TM) atoms. Modelling is done for a 4x4 silicene supercell with a single vacancy. The resulting structure is, thus, doped with 4d transition metal atoms. Doping results in lattice distortion, as evidenced by the variance in Si-TM bond length relative to Si-Si bond length. The shortest bond length is noticed in the instance of Ru doping, thus demonstrating its strongest bonding with Si atoms. Doping causes the structure to become increasingly deformed, as proved by the elevation in buckling height as well. Except for Zr, Ru and Pd, which exhibit semiconductor behaviour, the 4d TM doping in silicene results in metallic characteristics as the bands cross the Fermi level in the majority of the configurations discussed here. A narrow band gap with a range of 2.1 to 252 meV is produced by doping silicene with Zr, Ru, and Pd. Magnetism is demonstrated by Nb, Mo, Tc, and Rh-doped structures, whereas the other structures are nonmagnetic. The presence of magnetism in these structures is primarily due to contributions from Si-3p, TM- 4d/5s orbitals, and their hybridization.

Silicon Prismanes: Calculation and Comparison of Heats of Formation

Background: The objects of this work are silicon prismanes - new highenergy materials that can be used in various electronic, optoelectronic, thermoelectric, and biological fields and compete with traditional chemical energy carriers. However, only compounds with hexasilacubane and octasilacubane have been synthesized to date. Synthesis of other silapismanes, and even more so polysilaprismanes, has not yet been achieved. Therefore, both the “simplest” and the highest silaprismanes are studied mainly theoretically, including by quantum chemistry methods. Objective and Methods: To expand information about the enthalpies of formation of "simple" (n = 2) and multilayer (n = 3-7) silicon prismanes using semiempirical calculation methods; bond lengths Si-Si and Si-H; compare them with the results of ab initio calculations already available in the literature. Results: The geometry was optimized by semiempirical methods, the enthalpies of formation, Si-Si and Si-H bond lengths, and the bond angles of the bilayer (m = 3-12) and some multilayer (n = 3-8 and m = 3-9) silaprismanes were determined. Comparison with the enthalpies of formation obtained using ab initio calculations shows that the enthalpies of formation obtained by the MINDO/3 method (Modified Intermediate Neglect of Differential Overlap, version 3) are closest to the results of ab initio calculations of two-layer silicon prismanes; and for multilayers - by the AM1 method (Austin Model 1). Large differences in the lengths of Si-H bonds determined ab initio and semi-empirically by both methods are not observed. As for the Si-Si bonds, the results of semi-empirical methods indicate the presence of the so-called auxetic effect in multilayer silaprismanes. Conclusion: We believe that in the future, the calculations carried out in this work and a comparative assessment of the enthalpies of formation obtained by calculation methods will help to overcome the problems associated with the synthesis of silicon prismanes.

Designing Efficient Si Quantum Dots and LEDs by Quantifying Ligand Effects.

The impact of colloidal silicon quantum dots (SiQDs) on next-generation light sources is promising. However, factors determining the efficiency of SiQDs, such as the photoluminescence (PL) wavelength, PL quantum yield (PLQY), and the SiQD LED performance based on the type of ligand, ligand coverage, stress, and dangling bonds, have not been quantified. Characterizing these variables would accelerate the design and implementation of SiQDs. Herein, colloidal SiQDs were synthesized by pyrolyzing hydrogen silsesquioxane and their surfaces were terminated with 1-decene by either thermal hydrosilylation (HT-SiQDs) or room-temperature hydrosilylation using PCl5 (RT-SiQD). As a result, PL, PL-excitation, and ultraviolet-visible absorption spectra were similar, but their PLQYs were significantly different: 54% (RT-SiQDs) vs 19% (HT-SiQDs). To understand their similarities and differences, surface coverages (dangling bonds, Si-H (≡Si-H1, ═Si-H2, and -Si-H3), Si-O-Si, Si-C, Si-Cl) were determined. A core stress analysis established that a single ligand terminated to a SiQD bond site stretched the Si-Si bond length by 0.3%. From the two well-defined SiQDs, the PLQY and SiQD LED efficiency were attributed to four factors: low coverage of insulator ligands, the Cl ligand effect on radiative and nonradiative rates, negligible dangling bonds, and a SiQD core with low tensile stress. The PLQY of the RT-SiQDs in toluene was 80%. In addition, the 20× electroluminescence intensity difference of the LEDs originated from a 10× difference in current density and a 2× difference in Auger recombination. The concepts demonstrated here can be applied to further improve the PLQY and LED efficiencies of SiQDs with other ligands.

Crystal structures of 2-bromo-1,1,1,3,3,3-hexa-methyl-2-(tri-methyl-sil-yl)tris-ilane and 2-bromo-1,1,1,3,3,3-hexa-isopropyl-2-(triiso-propyl-sil-yl)tri-silane.

The synthesis and crystal structures of two tris-(tri-alkyl-sil-yl)silyl bromide compounds, C9H27BrSi4 (I, HypSiBr) and C27H63BrSi4 (II, TipSiBr), are described. Compound I was prepared in 85% yield by free-radical bromination of 1,1,1,3,3,3-hexa-methyl-2-(tri-methyl-sil-yl)tris-ilane using bromo-butane and 2,2'-azobis(2-methyl-propio-nitrile) as a radical initiator at 333 K. The mol-ecule possesses threefold rotational symmetry, with the central Si atom and the Br atom being located on the threefold rotation axis. The Si-Br bond distance is 2.2990 (12) Å and the Si-Si bond lengths are 2.3477 (8) Å. The Br-Si-Si bond angles are 104.83 (3)° and the Si-Si-Si bond angles are 113.69 (2)°, reflecting the steric hindrance inherent in the three tri-methyl-silyl groups attached to the central Si atom. Compound II was prepared in 55% yield by free-radical bromination of 1,1,1,3,3,3-hexa-isopropyl-2-(triiso-propyl-sil-yl)tris-ilane using N-bromo-succinimide and 2,2'-azobis(2-methyl-propio-nitrile) as a radical initiator at 353 K. Here the Si-Br bond length is 2.3185 (7) Å and the Si-Si bond lengths range from 2.443 (1) to 2.4628 (9) Å. The Br-Si-Si bond angles range from 98.44 (3) to 103.77 (3)°, indicating steric hindrance between the three triiso-propyl-silyl groups.

Metal-like Band Structures of Ultrathin Si {111} and {112} Surface Layers Revealed through Density Functional Theory Calculations.

Density functional theory calculations have been performed on Si (100), (110), (111), and (112) planes with tunable number of planes for evaluation of their band structures and density of states profiles. The purpose is to see whether silicon can exhibit facet-dependent properties derived from the presence of a thin surface layer having different band structures. No changes have been observed for single to multiple layers of Si (100) and (110) planes with a consistent band gap between the valence band and the conduction band. However, for 1, 2, 4, and 5 Si (111) and (112) planes, metal-like band structures were obtained with continuous density of states going from the valence band to the conduction band. For 3, 6, and more Si (111) planes, as well as 3 and 6 Si (112) planes, the same band structure as that seen for Si (100) and (110) planes has been obtained. Thus, beyond a layer thickness of five Si (111) planes at ≈1.6 nm, normal semiconductor behavior can be expected. The emergence of metal-like band structures for the Si (111) and (112) planes are related to variation in Si-Si bond length and bond distortion plus 3s and 3p orbital electron contributions in the band structure. This work predicts possession of facet-dependent electrical properties of silicon with consequences in FinFET transistor design.

Silicene Nanoribbon Tunnel Field Effect Transistor

Scaling of metal oxide semiconductor field effect transistor (MOSFET) following the Moore’s law is approaching to its near end as the power dissipation at the chip level is becoming increasingly difficult to reduce [1]. The International Technology Roadmap for Semiconductors (ITRS) considers several non-classical devices as a future replacement of silicon-based MOSFETs among which tunnel field effect transistor (TFET) is found to be promising [2, 3]. Compared to bulk three dimensional material based TFETs, study of TFETs based on two dimensional atomically thick materials have shown potential to operate at low supply voltage with a low subthreshold slope (SS) compared to 60mV/decade in conventional MOSFETs [4]. Different forms of two dimensional materials are studied such as Dirac cone materials (graphene, silicene, gemanene, stanene), transition metal dichalcogenides (TMD), transition oxides (TO) and topological insulators (TI). Compared to the study of TFET based on other two dimensional materials, silicene TFET remained large unexplored. Silicene is the two dimensional atomically thick planer form of bulk silicon. Stable room temperature operation of FET based on silicene has recently been reported [5]. Like graphene, silicene is a Dirac cone material with devices which provide high off-state leakage current due to the lack of a significant bandgap. However, quantum confined silicene nanoribbon (SiNR) shows observable bandgap making it suitable for digital applications [6]. Moreover, being an allotrope of silicon, silicene is also expected to be suitable for fabrication technology. Here, we present our work on SiNR TFET using atomistic simulation based on self-consistent solution of the 3D Poisson and Schrödinger equations within the non-equilibrium Green’s function (NEGF) formalism. SiNR has two types of edges, armchair and zigzag. We have considered armchair configuration in our study for a channel length of 10nm of a double gate SiNR TFET. Source and drain are 10nm each. Our default SiNR width is ~4nm providing a band gap of 1.42eV. Top and bottom gate oxides of our studied TFET are 2nm of SiO2. The effective tight binding Hamiltonian is adopted from the work of Voon et al. [7] and is simulated using the simulation code proposed in [8] for Si-Si bond length of 2.25Å and hoping integral of -6.43eV with -1.12eV correction at the SiNR edges [7]. The n+-type source and p+-type drain are doped with a molecular fraction of 0.001. A drain source voltage (VDS) of 0.3V is considered in this work. The studied SiNR TFET provides an on/off current ratio of ~107 with an average steep subthreshold slope (SS) of 6mV/decade for VDS=0.3V. A record low ~0.75x10-11pW/μm off-state leakage power is estimated. We have found that the leakage level increases as the supply voltage increases. The off-state leakage current increases to 0.6pA/μm as VDS increases from 0.3V to 0.95V. As the width of SiNR increases and the corresponding band gap decreases, leakage current also increases at small band gap with a reduction in on/off current ratio. The steep subthreshold slope of our studied SiNR TFET suits low power operation. With a suitable high-k dielectric and low gate oxide thickness, on-state drive current can be improved. Performance of SiNR TFET is also compared with ITRS projected high performance (HP) requirements of 2026 nMOSFET where SiNR TFET exceeds the performance of 2026 nMOSFET by 1014 times less power dissipation at 103 times higher on/off current ratio. Acknowledgement: Part of the work is supported by the United States Air Force Research Laboratory under agreement number FA9453-10-1-0002. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation thereon.

A Triatomic Silicon(0) Cluster Stabilized by a Cyclic Alkyl(amino) Carbene.

Reduction of the neutral carbene tetrachlorosilane adduct (cAAC)SiCl4 (cAAC=cyclic alkyl(amino) carbene :C(CMe2)2 (CH2)N(2,6-iPr2C6H3) with potassium graphite produces stable (cAAC)3Si3, a carbene-stabilized triatomic silicon(0) molecule. The Si-Si bond lengths in (cAAC)3Si3 are 2.399(8), 2.369(8) and 2.398(8) Å, which are in the range of Si-Si single bonds. Each trigonal pyramidal silicon atom of the triangular molecule (cAAC)3Si3 possesses a lone pair of electrons. Its bonding, stability, and electron density distributions were studied by quantum chemical calculations.

Quasi-particle calculations on electronic and optical properties of the peroxy linkage and neutral oxygen vacancy defects in amorphous silica

Recently, fused silica has been used to prepare the optical windows in the inertial confinement fusion (ICF) equipment. Challenge of application of fused silica is due to the defect-related optical absorption which is considered as the main mechanism of laser-induced damage process. However, due to structural complexity, calculation of the defect-related absorption from the first principles is only limited to small clusters, and a full treatment using the state of art GW and Bathe-Salpeter equation (BSE) method is still lacking.In this work, density functional theory calculations are performed to study the defect structure of the peroxy linkage (POL) and the neutral oxygen vacancy (NOV) defects in amorphous silica. Firstly, well relaxed structure is generated by using a combination of the bond switching Monte Carlo technique and the DFT-based structure optimization. Secondly, the defect structures are generated and studied in both the ground singlet (S0) and the first excited triplet (T1) states. Finally, the electronic and optical properties of the considered structures are studied by applying the self-consistent quasi-particle GW (sc-QPGW) and the BSE methods in Tamm-Dankoff approximation.In the ground state S0, the POL defect is found to be stable and shares a similar local structure to the H2O2 molecule. However, in T1 state, the POL defect breaks into a pair of E' center ( - Si ) and peroxy oxygen radial ( O-O-Si-). For the NOV defect, the optimized Si-Si bond length in the ground state is 2.51 with a variation of 0.1 due to the structural disorder. In comparison to the ground state, the optimized Si-Si bond length in T1 state increases to 3.56 .The scGW/BSE calculation on the defect free structure predicts a quasi particle band gap of 10.1 eV and an optical band gap of 8.0 eV, which are consistent well with the available experimental results. For the POL defect, the scGW/BSE calculation reveals a weak exciton peak at 6.3 eV. Below 6.3 eV, no new exciton peak is found, implying that the experimentally suggested 3.8 eV peak could not be attributed to the POL defect. Calculations of the NOV defect gives a strong and highly polarized optical absorption peak at 7.4 eV which is close to the previous experimental result at 7.6 eV. The structural relaxation induced by NOV also contributes to another absorption peak at 7.8 eV.

The Optical Properties of Doped Silicon Nanotubes

We perform the first-principles calculations within the framework of density functional theory to determine the electronic structure and optical properties of P-doped and B-doped silicon nanotubes. The results indicate that the electronic structure and optical properties of P-doped and B-doped silicon nanotubes are sensitive to the impurity composition. In particular, when doped with P or B, obviously the band gap decreases and the conductivity enhanced, the P-doped and B-doped silicon nanotubes displays a closer band structure and the unit cell volume of doped silicon nanotubes increased than before doping, the change depends on the doping charge and Si-Si bond length dSi-Si. Moreover, the dielectric constant decreases and increased when doped P and B, the optical absorption peak obviously has a blue shift and red shift respectively. The calculated results provide important theoretical guidance for the applications of Uv detector and the solar cell in optical detectors.

Tunable gaps and enhanced mobilities in strain-engineered silicane

The recent demonstration of single-atom thick, sp3-hybridized group 14 analogues of graphene enables the creation of materials with electronic structures that are manipulated by the nature of the covalently bound substituents above and below the sheet. These analogues can be electronically derived from isolated (111) layers of the bulk diamond lattice. Here, we perform systematic Density Functional Theory calculations to understand how the band dispersions, effective masses, and band gaps change as the bulk silicon (111) layers are continuously separated from each other until they are electronically isolated, and then passivated with hydrogen. High-level calculations based on HSE06 hybrid functionals were performed on each endpoint to compare directly with experimental values. We find that the change in the electronic structure due to variations in the Si-H bond length, Si-Si-Si bond angle, and most significantly the Si-Si bond length can tune the nature of the band gap from indirect to direct with dramatic effects on the transport properties. First-principles calculations of the phonon-limited electron mobility predict a value of 464 cm2/Vs for relaxed indirect band gap Si-H monolayers at room temperature. However, for 1.6% tensile strain, the band gap becomes direct, which increases the mobility significantly (8 551 cm2/Vs at 4% tensile strain). In total, this analysis of Si-based monolayers suggests that strain can change the nature of the band gap from indirect to direct and increase the electron mobility more than 18-fold.

Determination of atomic positions in silicene on Ag(111) by low-energy electron diffraction

We have investigated the structure of silicene forming into the (4×4) superstructure on Ag(111) by using the low-energy electron diffraction. We found that Si atoms form a buckled honeycomb structure on Ag(111), which fully matches with the structure optimized with the density functional theory calculations. The SiSi bond lengths range from 2.29 to 2.31Å, which are close to the upper limit of SiSi double bond and shorter than the bond length in the bulk diamond structure. The buckling in the silicene layer causes the displacement of Ag atoms in the first substrate layer with 0.3Å perpendicular to the surface, which is a compelling evidence of the strong couplings at the interface between the silicene and the substrate.

Synthesis and Solid-State Molecular Structure of Bi(silacyclohexyls) C5H10SiX-XSiC5H10 with X = H, PH, F, CL, BR, and I

The synthesis and purification of novel bi(silacyclohexyls) C5H10SiX-XSiC5H10 with X = H (1), Ph (2), F (3), Cl (4), Br (5), and I (6), which are composed of two silacyclohexyl rings connected by a silicon–silicon single bond, is described. Molecular structures for 2, 4, 5, and 6 were determined employing X-ray crystallography. Surprisingly, the SiSi bond lengths increase in the order I < Br < Cl, contrary to what is observed for methylated disilanes Me2XSiSiXMe2. The bond lengthening can be traced back to 1, 3 nonbonded interactions between the halogen atoms and the axial hydrogen atoms in the SiC5 ring, which also cause a decrease of the SiSiX bond angles with increasing size of the halogen atom. Both rings substitute each other in the equatorial position for 4, 5, and 6, but in the axial position for 2.

Structure and Reactivity of (η5-Cyclopentadienyl)(triphenylphosphine)- (undecamethylcyclohexasilyl)nickel(II)-Hexane (2/1) Structure and Reactivity of (η5-Cyclopentadienyl)(triphenylphosphine)- (undecamethylcyclohexasilyl)nickel(II)-Hexane (2/1)

The nickel cyclohexasilyl complex CpNi(PPh3)Si6Me11 was synthesized from nickelocene, triphenylphosphine, and undecamethylcyclohexasilyl potassium and was fully characterized. It shows a relationship between its Si-Si bond lengths and its reactivity towards oxygen. The cleavage of one cyclopentadienyl ligand from nickelocene by silyl anions in the presence of additional ligands opens a promising new pathway to nickel silyl complexes of the type CpNi(L)-SiR3

Computer simulation of the tension of noncrystalline silicon nanoparticles

Vitreous and amorphous silicon nanoparticles consisting of 500 atoms are investigated using the molecular dynamics method after a series of uniform tensions with a total tensile strain Δl/l ≈ 0.10 and subsequent relaxation. The disappearance of the second peak in the radial distribution function for an amorphous nanoparticle subjected to a uniform tension with a tensile strain Δl/l ≈ 0.06 indicates the destruction of the tetrahedral packing. In nanoparticles of both types, the energetically most favorable atomic packing is retained in middle layers for all the strains under investigation. The distribution of Si-Si bond lengths and the larger mean number of bonds per atom suggest that the structure of the vitreous nanoparticle is characterized by a higher statistical resistance to tension. This nanoparticle also has a higher kinetic resistance to uniform tension. Unlike the amorphous nanoparticle, the radial component of the coefficient of mobility of atoms in the vitreous nanoparticle neither dominates over its tangential component nor increases regularly in going from the center of mass of the nanoparticle toward the nanoparticle surface. As the number of tensions increases, the mean length of Si-Si bonds decreases in the vitreous nanoparticle and, by contrast, increases in the amorphous nanoparticle.

Growth and Atomistic Structure Study of Disordered SiGe Mixed Semiconductors

The atomistic structure of Czochralski-grown SixGe1-x binary mixed semiconductor was studied experimentally and theoretically. By extended X-ray absorption fine structure (XAFS) studies it was found that bulk SiGe semiconductor is a random mixture and that the Ge-Ge, Ge-Si and Si-Si bond lengths maintain distinctly different lengths and vary in a linear fashion against the alloy composition across the whole composition range 0 &lt; x &lt; 1, in good agreement with expectations derived from the ab-inito electronic structure calculations. The result indicates that SiGe is a suitable model for a disorder mixed material and that the bond lengths and bond angles are distorted with the composition.

Magnetic properties of transition metal atoms doped in silicon nanotubes with hexagonal prism structure

Magnetic properties of magnetic transition metals doped in the infinite Si nanotubes (SiNTs) with hexagonal prism structure (Si/sub 12/M/sub n/, M=Fe, Co, Ni, n=1, 2) have been investigated for two different numbers of dopants per hexagonal prism by using the localized basis calculational method. The decrease (increase) of spin-down (spin-up) electrons for the n=2 case results in the increase of magnetic moments compared with the n=1 case. The calculated magnetic moment per dopant Fe atom (2.39 /spl mu//sub B/) is larger than both of the bulk value (2.22 /spl mu//sub B/) and previous result for finite nanotube (1.7 /spl mu//sub B/). For Co and Ni atoms doped in the tube, the magnetic moments are smaller than those of bulk metals. The Si-Si bond lengths for the hexagonal prisms decrease compared with that of the nanotube without transition metals, but there is no dependency on different dopants. The distances between the transition metals and Si atoms decrease as the atomic number of transition metals increases, which is the same trend for the atomic radii of transition metal atoms. The doping of transition metal atoms leads to the increase of the binding energy (BE).

Cyclotrisilenylium Ion: The Persilaaromatic Compound

The highly crowded 3,3-bis(di-tert-butylmethylsilyl)-1,2-bis(tri-tert-butylsilyl)cyclotrisilene (3) was newly designed as a precursor of the cyclotrisilenylium ion and prepared by the reaction of 2 equiv of dilithiosilane (tBu2MeSi)2SiLi2 (1) with 2,2,3,3-tetrabromo-1,1,1,4,4,4-hexa-tert-butyltetrasilane. The reaction of 3 with triphenylmethylium tetraarylborate in toluene produced (di-tert-butylmethylsilyl)bis(tri-tert-butylsilyl)cyclotrisilenylium ion (4+), which was isolated in the form of the tetraarylborate salt as extremely air- and moisture-sensitive yellow crystals, representing the first isolable silicon congener of the cyclopropenylium ion. The molecular structure of 4+.TSFPB- (TSFPB- = tetrakis[4-(tert-butyldimethylsilyl)-2,3,5,6-tetrafluorophenyl]borate) was established by X-ray crystallographic analysis, showing that the three-membered ring constitutes an almost equilateral triangle with average Si-Si bond lengths of 2.216(3) A. The X-ray crystal structure and spectral data show that 4+ is not only a free silyl cation but also a 2pi electron aromatic species with delocalization of the positive charge over the three-membered skeleton.

The Silicon Hydride Clusters Si3Hn (n ≤ 8) and Their Anions: Structures, Thermochemistry, and Electron Affinities

AbstractFor Abstract see ChemInform Abstract in Full Text.