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Inorganics
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Coordination Chemistry of Silicon
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Coordination Chemistry of Silicon

A special issue of Inorganics (ISSN 2304-6740). This special issue belongs to the section "Coordination Chemistry".

Deadline for manuscript submissions: closed (30 June 2018) | Viewed by 81536

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editor

Prof. Dr. Shigeyoshi Inoue

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Guest Editor
Department of Chemistry, Institute of Silicon Chemistry and Catalysis Research Center, Technische Universität München, 85748 Garching, Germany
Interests: main group chemistry; organometallic chemistry; coordination chemistry; silicon chemistry; catalysis
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The chemistry of silicon has always been a field of major concern due to its proximity to carbon on the periodic table. From the molecular chemist’s viewpoint, one of the most interesting differences between carbon and silicon is their divergent coordination behavior. In fact, silicon is prone to form hyper-coordinate organosilicon complexes and, as conveyed by reports in the literature, highly sophisticated ligand systems are required to furnish low-coordinate organosilicon complexes. Tremendous progress in experimental, as well as computational techniques has granted synthetic access to a broad range of coordination numbers for silicon, and the scientific endeavor, ongoing for decades, was rewarded with landmark discoveries in the field of organosilicon chemistry. Molecular congeners of silicon(0), as well as silicon oxides were unveiled and the prominent group 14 metalloid proved its applicability in homogenous catalysis as a supportive ligand or even as a center of catalytic activity. This Special Issue focuses on the most recent advances in coordination chemistry of silicon with transition metals as well as main group elements, including the stabilization of low-valent silicon species through the coordination of electron donor ligands. Therefore, this issue is associated with the development of novel synthetic methodologies, structural elucidations, bonding analysis, and also possible applications in catalysis or chemical transformations using related organosilicon compounds. 

Prof. Dr. Shigeyoshi Inoue
Guest Editor

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Keywords

  • Transition metal complexes with silicon based ligands
  • Main group element complexes with silicon based ligands
  • Donor stabilized low valent silicon compounds
  • Donor stabilized silicon cations
  • Hypercoordinate silicon compounds
  • Bond Activation
  • Catalysis

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Editorial

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4 pages, 153 KiB  
Editorial
Coordination Chemistry of Silicon
by Shigeyoshi Inoue
Inorganics 2019, 7(1), 7; https://doi.org/10.3390/inorganics7010007 - 14 Jan 2019
Viewed by 2471
Abstract
It is with great pleasure to welcome readers to this Special Issue of Inorganics, devoted to “Coordination Chemistry of Silicon” [...] Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)

Research

Jump to: Editorial, Review

19 pages, 3929 KiB  
Article
(2-Pyridyloxy)silanes as Ligands in Transition Metal Coordination Chemistry
by Lisa Ehrlich, Robert Gericke, Erica Brendler and Jörg Wagler
Inorganics 2018, 6(4), 119; https://doi.org/10.3390/inorganics6040119 - 31 Oct 2018
Cited by 16 | Viewed by 4327
Abstract
Proceeding our initial studies of compounds with formally dative TM→Si bonds (TM = Ni, Pd, Pt), which feature a paddlewheel arrangement of four (N,S) or (N,N) bridging ligands around the TM–Si axis, the current study [...] Read more.
Proceeding our initial studies of compounds with formally dative TM→Si bonds (TM = Ni, Pd, Pt), which feature a paddlewheel arrangement of four (N,S) or (N,N) bridging ligands around the TM–Si axis, the current study shows that the (N,O)-bidentate ligand 2-pyridyloxy (pyO) is also capable of bridging systems with TM→Si bonds (shown for TM = Pd, Cu). Reactions of MeSi(pyO)3 with [PdCl2(NCMe)2] and CuCl afforded the compounds MeSi(µ-pyO)4PdCl (1) and MeSi(µ-pyO)3CuCl (2), respectively. In the latter case, some crystals of the Cu(II) compound MeSi(µ-pyO)4CuCl (3) were obtained as a byproduct. Analogous reactions of Si(pyO)4, in the presence of HpyO, with [PdCl2(NCMe)2] and CuCl2, afforded the compounds [(HpyO)Si(µ-pyO)4PdCl]Cl (4), (HpyO)2Si[(µ-pyO)2PdCl2]2 (5), and (HpyO)2Si[(µ-pyO)2CuCl2]2 (6), respectively. Compounds 1–6 and the starting silanes MeSi(pyO)3 and Si(pyO)4 were characterized by single-crystal X-ray diffraction analyses and, with exception of the paramagnetic compounds 3 and 6, with NMR spectroscopy. Compound 2 features a pentacoordinate Si atom, the Si atoms of the other complexes are hexacoordinate. Whereas compounds 1–4 feature a TM→Si bond each, the Si atoms of compounds 5 and 6 are situated in an O6 coordination sphere, while the TMCl2 groups are coordinated to pyridine moieties in the periphery of the molecule. The TM–Si interatomic distances in compounds 1–4 are close to the sum of the covalent radii (1 and 4) or at least significantly shorter than the sum of the van-der-Waals radii (2 and 3). The latter indicates a noticeably weaker interaction for TM = Cu. For the series 1, 2, and 3, all of which feature the Me–Si motif trans-disposed to the TM→Si bond, the dependence of the TM→Si interaction on the nature of TM (Pd(II), Cu(I), and Cu(II)) was analyzed using quantum chemical calculations, that is, the natural localized molecular orbitals (NLMO) analyses, the non-covalent interaction (NCI) descriptor, Wiberg bond order (WBO), and topological characteristics of the bond critical points using the atoms in molecules (AIM) approach. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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12 pages, 4471 KiB  
Article
Transformative Si8R8 Siliconoids
by Naohiko Akasaka, Shintaro Ishida and Takeaki Iwamoto
Inorganics 2018, 6(4), 107; https://doi.org/10.3390/inorganics6040107 - 03 Oct 2018
Cited by 13 | Viewed by 3418
Abstract
Molecular silicon clusters with unsubstituted silicon vertices (siliconoids) have received attention as unsaturated silicon clusters and potential intermediates in the gas-phase deposition of elemental silicon. Investigation of behaviors of the siliconoids could contribute to the greater understanding of the transformation of silicon clusters [...] Read more.
Molecular silicon clusters with unsubstituted silicon vertices (siliconoids) have received attention as unsaturated silicon clusters and potential intermediates in the gas-phase deposition of elemental silicon. Investigation of behaviors of the siliconoids could contribute to the greater understanding of the transformation of silicon clusters as found in the chemical vapor deposition of elemental silicon. Herein we reported drastic transformation of a Si8R8 siliconoid to three novel silicon clusters under mild thermal conditions. Molecular structures of the obtained new clusters were determined by XRD analyses. Two clusters are siliconoids that have unsaturated silicon vertices adopting unusual geometries, and another one is a bis(disilene) which has two silicon–silicon double bonds interacted to each other through the central polyhedral silicon skeleton. The observed drastic transformation of silicon frameworks suggests that unsaturated molecular silicon clusters have a great potential to provide various molecular silicon clusters bearing unprecedented structures and properties. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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14 pages, 1228 KiB  
Article
Stepwise Introduction of Different Substituents to α-Chloro-ω-hydrooligosilanes: Convenient Synthesis of Unsymmetrically Substituted Oligosilanes
by Ken-ichiro Kanno, Yumi Aikawa, Yuka Niwayama, Misaki Ino, Kento Kawamura and Soichiro Kyushin
Inorganics 2018, 6(3), 99; https://doi.org/10.3390/inorganics6030099 - 18 Sep 2018
Cited by 8 | Viewed by 3159
Abstract
A series of unsymmetrically substituted oligosilanes were synthesized via stepwise introduction of different substituents to α-chloro-ω-hydrooligosilanes. The reactions of α-chloro-ω-hydrooligosilanes with organolithium or Grignard reagents gave hydrooligosilanes having various alkyl, alkenyl, alkynyl and aryl groups. Thus-obtained hydrooligosilanes were converted into alkoxyoligosilanes by ruthenium-catalyzed [...] Read more.
A series of unsymmetrically substituted oligosilanes were synthesized via stepwise introduction of different substituents to α-chloro-ω-hydrooligosilanes. The reactions of α-chloro-ω-hydrooligosilanes with organolithium or Grignard reagents gave hydrooligosilanes having various alkyl, alkenyl, alkynyl and aryl groups. Thus-obtained hydrooligosilanes were converted into alkoxyoligosilanes by ruthenium-catalyzed dehydrogenative alkoxylation with alcohols. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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8 pages, 1786 KiB  
Article
Synthesis and Characterization of the Germathioacid Chloride Coordinated by an N-Heterocyclic Carbene §
by Yasunobu Egawa, Chihiro Fukumoto, Koichiro Mikami, Nobuhiro Takeda and Masafumi Unno
Inorganics 2018, 6(3), 76; https://doi.org/10.3390/inorganics6030076 - 03 Aug 2018
Cited by 2 | Viewed by 3301
Abstract
Carboxylic acid chlorides are useful substrates in organic chemistry. Many germanium analogues of carboxylic acid chloride have been synthesized so far. Nevertheless, all of the reported germathioacid chlorides use bidentate nitrogen ligands and contain germanium-nitrogen bonds. Our group synthesized germathioacid chloride, Ge(S)Cl{C6 [...] Read more.
Carboxylic acid chlorides are useful substrates in organic chemistry. Many germanium analogues of carboxylic acid chloride have been synthesized so far. Nevertheless, all of the reported germathioacid chlorides use bidentate nitrogen ligands and contain germanium-nitrogen bonds. Our group synthesized germathioacid chloride, Ge(S)Cl{C6H3-2,6-Tip2}(Im-i-Pr2Me2), using N-heterocyclic carbene (Im-i-Pr2Me2). As a result of density functional theory (DFT) calculation, it was found that electrons are localized on sulfur, and the germanium-sulfur bond is a single bond with a slight double bond property. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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6 pages, 683 KiB  
Article
One-Pot Synthesis of Heavier Group 14 N-Heterocyclic Carbene Using Organosilicon Reductant
by Ravindra K. Raut, Sheikh Farhan Amin, Padmini Sahoo, Vikas Kumar and Moumita Majumdar
Inorganics 2018, 6(3), 69; https://doi.org/10.3390/inorganics6030069 - 12 Jul 2018
Cited by 7 | Viewed by 4380
Abstract
Syntheses of heavier Group 14 analogues of “Arduengo-type” N-heterocyclic carbene majorly involved the use of conventional alkali metal-based reducing agents under harsh reaction conditions. The accompanied reductant-derived metal salts and chances of over-reduced impurities often led to isolation difficulties in this multi-step [...] Read more.
Syntheses of heavier Group 14 analogues of “Arduengo-type” N-heterocyclic carbene majorly involved the use of conventional alkali metal-based reducing agents under harsh reaction conditions. The accompanied reductant-derived metal salts and chances of over-reduced impurities often led to isolation difficulties in this multi-step process. In order to overcome these shortcomings, we have used 1,4-bis-(trimethylsilyl)-1,4-diaza-2,5-cyclohexadiene as a milder reducing agent for the preparation of N-heterocyclic germylenes (NHGe) and stannylenes (NHSn). The reaction occurs in a single step with moderate yields from the mixture of N-substituted 1,4-diaza-1,3-butadiene, E(II) (E(II) = GeCl2·dioxane, SnCl2) and the organosilicon reductant. The volatile byproducts trimethylsilyl chloride and pyrazine could be removed readily under vacuum. No significant over reduction was observed in this process. However, N-heterocyclic silylene (NHSi) could not be synthesized using an even stronger organosilicon reductant under thermal and photochemical conditions. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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14 pages, 1967 KiB  
Article
S–H Bond Activation in Hydrogen Sulfide by NHC-Stabilized Silyliumylidene Ions
by Amelie Porzelt, Julia I. Schweizer, Ramona Baierl, Philipp J. Altmann, Max C. Holthausen and Shigeyoshi Inoue
Inorganics 2018, 6(2), 54; https://doi.org/10.3390/inorganics6020054 - 24 May 2018
Cited by 16 | Viewed by 5524
Abstract
Reactivity studies of silyliumylidenes remain scarce with only a handful of publications to date. Herein we report the activation of S–H bonds in hydrogen sulfide by mTer-silyliumylidene ion A (mTer = 2,6-Mes2-C6H3, Mes = [...] Read more.
Reactivity studies of silyliumylidenes remain scarce with only a handful of publications to date. Herein we report the activation of S–H bonds in hydrogen sulfide by mTer-silyliumylidene ion A (mTer = 2,6-Mes2-C6H3, Mes = 2,4,6-Me3-C6H2) to yield an NHC-stabilized thiosilaaldehyde B. The results of NBO and QTAIM analyses suggest a zwitterionic formulation of the product B as the most appropriate. Detailed mechanistic investigations are performed at the M06-L/6-311+G(d,p)(SMD: acetonitrile/benzene)//M06-L/6-311+G(d,p) level of density functional theory. Several pathways for the formation of thiosilaaldehyde B are examined. The energetically preferred route commences with a stepwise addition of H2S to the nucleophilic silicon center. Subsequent NHC dissociation and proton abstraction yields the thiosilaaldehyde in a strongly exergonic reaction. Intermediacy of a chlorosilylene or a thiosilylene is kinetically precluded. With an overall activation barrier of 15 kcal/mol, the resulting mechanistic picture is fully in line with the experimental observation of an instantaneous reaction at sub-zero temperatures. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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8 pages, 1031 KiB  
Article
Predicted Siliconoids by Bridging Si9 Clusters through sp3-Si Linkers
by Laura-Alice Jantke and Thomas F. Fässler
Inorganics 2018, 6(1), 31; https://doi.org/10.3390/inorganics6010031 - 26 Feb 2018
Cited by 7 | Viewed by 3329
Abstract
Charged and neutral silicon clusters comprising Si atoms that are exclusively connected to atoms of the same type serve as models for bulk silicon surfaces. The experimentally known nido-[Si9]4− Zintl cluster is investigated as a building block and allows [...] Read more.
Charged and neutral silicon clusters comprising Si atoms that are exclusively connected to atoms of the same type serve as models for bulk silicon surfaces. The experimentally known nido-[Si9]4− Zintl cluster is investigated as a building block and allows for a theoretical prediction of novel silicon-rich oligomers and polymers by interconnection of such building units to larger aggregates. The stability and electronic properties of the polymers { ( [ Si 9 ] – ( SiCl 2 ) 2 ) ∞ 1 n } and { ( [ Si 9 ] – ( SiH 2 ) 2 ) ∞ 1 n } , as well as of related oligomers are presented. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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11 pages, 1570 KiB  
Article
Synthesis and Characterization of N-Heterocyclic Carbene-Coordinated Silicon Compounds Bearing a Fused-Ring Bulky Eind Group
by Naoki Hayakawa, Kazuya Sadamori, Shinsuke Mizutani, Tomohiro Agou, Tomohiro Sugahara, Takahiro Sasamori, Norihiro Tokitoh, Daisuke Hashizume and Tsukasa Matsuo
Inorganics 2018, 6(1), 30; https://doi.org/10.3390/inorganics6010030 - 23 Feb 2018
Cited by 13 | Viewed by 4926
Abstract
The reactions of the fused-ring bulky Eind-substituted 1,2-dibromodisilene, (Eind)BrSi=SiBr(Eind) (1a) (Eind = 1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl (a)), with N-heterocyclic carbenes (NHCs) (Im-Me4 = 1,3,4,5-tetramethylimidazol-2-ylidene and Im-iPr2Me2 = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) are reported. While the reaction [...] Read more.
The reactions of the fused-ring bulky Eind-substituted 1,2-dibromodisilene, (Eind)BrSi=SiBr(Eind) (1a) (Eind = 1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl (a)), with N-heterocyclic carbenes (NHCs) (Im-Me4 = 1,3,4,5-tetramethylimidazol-2-ylidene and Im-iPr2Me2 = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) are reported. While the reaction of 1a with the sterically more demanding Im-iPr2Me2 led to the formation of the mono-NHC adduct of arylbromosilylene, (Im-iPr2Me2)→SiBr(Eind) (2a′), a similar reaction using the less bulky Im-Me4 affords the bis-NHC adduct of formal arylsilyliumylidene cation, [(Im-Me4)2→Si(Eind)]+[Br−] (3a). The NHC adducts 2a′ and 3a can also be prepared by the dehydrobromination of Eind-substituted dibromohydrosilane, (Eind)SiHBr2 (4a), with NHCs. The NHC-coordinated silicon compounds have been characterized by spectroscopic methods. The molecular structures of bis-NHC adduct, [(Im-iPr2Me2)2→Si(Eind)]+[Br−] (3a′), and 4a have been determined by X-ray crystallography. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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15 pages, 2904 KiB  
Article
Synthesis and Functionalization of a 1,2-Bis(trimethylsilyl)-1,2-disilacyclohexene That Can Serve as a Unit of cis-1,2-Dialkyldisilene
by Naohiko Akasaka, Kaho Tanaka, Shintaro Ishida and Takeaki Iwamoto
Inorganics 2018, 6(1), 21; https://doi.org/10.3390/inorganics6010021 - 24 Jan 2018
Cited by 4 | Viewed by 4496
Abstract
π-Electron compounds that include multiple bonds between silicon atoms have received much attention as novel functional silicon compounds. In the present paper, 1,2-bis(trimethylsilyl)-1,2-disilacyclohexene 1 was successfully synthesized as thermally stable yellow crystals. Disilene 1 was easily converted to the corresponding potassium disilenide 4 [...] Read more.
π-Electron compounds that include multiple bonds between silicon atoms have received much attention as novel functional silicon compounds. In the present paper, 1,2-bis(trimethylsilyl)-1,2-disilacyclohexene 1 was successfully synthesized as thermally stable yellow crystals. Disilene 1 was easily converted to the corresponding potassium disilenide 4, which furnished novel functionalized disilenes after the subsequent addition of an electrophile. Interestingly, two trimethylsilyl groups in 1 can be stepwise converted to anthryl groups. The novel disilenes derived from 1 were characterized by a combination of nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry (MS), elemental analyses, and X-ray single crystal diffraction analysis. The present study demonstrates that disilene 1 can serve as a unit of cis-1,2-dialkyldisilene. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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14 pages, 2849 KiB  
Article
Bond Insertion at Distorted Si(001) Subsurface Atoms
by Lisa Pecher and Ralf Tonner
Inorganics 2018, 6(1), 17; https://doi.org/10.3390/inorganics6010017 - 23 Jan 2018
Cited by 9 | Viewed by 4743
Abstract
Using density functional theory (DFT) methods, we analyze the adsorption of acetylene and ethylene on the Si(001) surface in an unusual bond insertion mode. The insertion takes place at a saturated tetravalent silicon atom and the insight gained can thus be transferred to [...] Read more.
Using density functional theory (DFT) methods, we analyze the adsorption of acetylene and ethylene on the Si(001) surface in an unusual bond insertion mode. The insertion takes place at a saturated tetravalent silicon atom and the insight gained can thus be transferred to other saturated silicon compounds in molecular and surface chemistry. Molecular orbital analysis reveals that the distorted and symmetry-reduced coordination of the silicon atoms involved due to surface reconstruction raises the electrophilicity and, additionally, makes certain σ bond orbitals more accessible. The affinity towards bond insertion is, therefore, caused by the structural constraints of the surface. Additionally, periodic energy decomposition analysis (pEDA) is used to explain why the bond insertion structure is much more stable for acetylene than for ethylene. The increased acceptor abilities of acetylene due to the presence of two π*-orbitals (instead of one π*-orbital and a set of σ*(C–H) orbitals for ethylene), as well as the lower number of hydrogen atoms, which leads to reduced Pauli repulsion with the surface, are identified as the main causes. While our findings imply that this structure might be an intermediate in the adsorption of acetylene on Si(001), the predicted product distributions are in contradiction to the experimental findings. This is critically discussed and suggestions to resolve this issue are given. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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10 pages, 1191 KiB  
Article
Hybrid Disila-Crown Ethers as Hosts for Ammonium Cations: The O–Si–Si–O Linkage as an Acceptor for Hydrogen Bonding
by Fabian Dankert, Kirsten Reuter, Carsten Donsbach and Carsten Von Hänisch
Inorganics 2018, 6(1), 15; https://doi.org/10.3390/inorganics6010015 - 16 Jan 2018
Cited by 13 | Viewed by 4302
Abstract
Host-guest chemistry was performed with disilane-bearing crown ethers and the ammonium cation. Equimolar reactions of 1,2-disila[18]crown-6 (1) or 1,2-disila-benzo[18]crown-6 (2) and NH4PF6 in dichloromethane yielded the respective compounds [NH4(1,2-disila[18]crown-6)]PF6 (3) and [...] Read more.
Host-guest chemistry was performed with disilane-bearing crown ethers and the ammonium cation. Equimolar reactions of 1,2-disila[18]crown-6 (1) or 1,2-disila-benzo[18]crown-6 (2) and NH4PF6 in dichloromethane yielded the respective compounds [NH4(1,2-disila[18]crown-6)]PF6 (3) and [NH4(1,2-disila-benzo[18]crown-6)]PF6 (4). According to X-ray crystallographic, NMR, and IR experiments, the uncommon hydrogen bonding motif O(Si)∙∙∙H could be observed and the use of cooperative effects of ethylene and disilane bridges as an effective way to incorporate guest molecules was illustrated. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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934 KiB  
Communication
Synthesis of a α-Chlorosilyl Functionalized Donor-Stabilized Chlorogermylene
by Debabrata Dhara, Volker Huch, David Scheschkewitz and Anukul Jana
Inorganics 2018, 6(1), 6; https://doi.org/10.3390/inorganics6010006 - 29 Dec 2017
Cited by 3 | Viewed by 4050
Abstract
Peripherally functionalized low-valent main group species allow for the introduction/interconversion of functional groups without increasing the formal oxidation state of the main group center. Herein, we report a straightforward method for the incorporation of a α-chlorosilyl moiety adjacent to the NHC-coordinated germanium(II) center. [...] Read more.
Peripherally functionalized low-valent main group species allow for the introduction/interconversion of functional groups without increasing the formal oxidation state of the main group center. Herein, we report a straightforward method for the incorporation of a α-chlorosilyl moiety adjacent to the NHC-coordinated germanium(II) center. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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3484 KiB  
Article
The Silacyclobutene Ring: An Indicator of Triplet State Baird-Aromaticity
by Rabia Ayub, Kjell Jorner and Henrik Ottosson
Inorganics 2017, 5(4), 91; https://doi.org/10.3390/inorganics5040091 - 15 Dec 2017
Cited by 5 | Viewed by 4316
Abstract
Baird’s rule tells that the electron counts for aromaticity and antiaromaticity in the first ππ* triplet and singlet excited states (T1 and S1) are opposite to those in the ground state (S0). Our hypothesis is that a silacyclobutene [...] Read more.
Baird’s rule tells that the electron counts for aromaticity and antiaromaticity in the first ππ* triplet and singlet excited states (T1 and S1) are opposite to those in the ground state (S0). Our hypothesis is that a silacyclobutene (SCB) ring fused with a [4n]annulene will remain closed in the T1 state so as to retain T1 aromaticity of the annulene while it will ring-open when fused to a [4n + 2]annulene in order to alleviate T1 antiaromaticity. This feature should allow the SCB ring to function as an indicator for triplet state aromaticity. Quantum chemical calculations of energy and (anti)aromaticity changes along the reaction paths in the T1 state support our hypothesis. The SCB ring should indicate T1 aromaticity of [4n]annulenes by being photoinert except when fused to cyclobutadiene, where it ring-opens due to ring-strain relief. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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2148 KiB  
Article
Molecular Structures of Enantiomerically-Pure (S)-2-(Triphenylsilyl)- and (S)-2-(Methyldiphenylsilyl)pyrrolidinium Salts
by Jonathan O. Bauer and Carsten Strohmann
Inorganics 2017, 5(4), 88; https://doi.org/10.3390/inorganics5040088 - 06 Dec 2017
Cited by 5 | Viewed by 3358
Abstract
Silyl-substituted pyrrolidines have gained increased interest for the design of new catalyst scaffolds. The molecular structures of four enantiomerically-pure 2-silylpyrrolidinium salts are reported. The perchlorate salts of (S)-2-(triphenylsilyl)pyrrolidine [(S)-1·HClO4] and (S)-2-(methyldiphenylsilyl)pyrrolidine [(S [...] Read more.
Silyl-substituted pyrrolidines have gained increased interest for the design of new catalyst scaffolds. The molecular structures of four enantiomerically-pure 2-silylpyrrolidinium salts are reported. The perchlorate salts of (S)-2-(triphenylsilyl)pyrrolidine [(S)-1·HClO4] and (S)-2-(methyldiphenylsilyl)pyrrolidine [(S)-2·HClO4], the trifluoroacetate (S)-2·TFA, and the methanol-including hydrochloride (S)-1·HCl·MeOH were elucidated by X-ray crystallography and discussed in terms of hydrogen-bond interactions. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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2095 KiB  
Communication
Construction of a Planar Tetrapalladium Cluster by the Reaction of Palladium(0) Bis(isocyanide) with Cyclic Tetrasilane
by Yusuke Sunada, Nobuhiro Taniyama, Kento Shimamoto, Soichiro Kyushin and Hideo Nagashima
Inorganics 2017, 5(4), 84; https://doi.org/10.3390/inorganics5040084 - 27 Nov 2017
Cited by 14 | Viewed by 4672
Abstract
The planar tetrapalladium cluster Pd4{Si(iPr)2}3(CNtBu)4 (4) was synthesised in 86% isolated yield by the reaction of palladium(0) bis(isocyanide) Pd(CNtBu)2 with octaisopropylcyclotetrasilane (3). In the course [...] Read more.
The planar tetrapalladium cluster Pd4{Si(iPr)2}3(CNtBu)4 (4) was synthesised in 86% isolated yield by the reaction of palladium(0) bis(isocyanide) Pd(CNtBu)2 with octaisopropylcyclotetrasilane (3). In the course of this reaction, the palladium atoms are clustered via insertion into the Si–Si bonds of 3, followed by extrusion of one SiiPr2 moiety and reorganisation to afford 4 with a 54-electron configuration. The CNtBu ligand in 4 was found to be easily replaced by N-heterocyclic carbene (iPr2IMMe) to afford the more coordinatively unsaturated cluster Pd4{Si(iPr)2}3(iPr2IMMe)3 (5) having the planar Pd4Si3 core. On the other hand, the replacement of CNtBu with a sterically compact ligand trimethylolpropane phosphite {P(OCH2)3CEt} led to a planar tripalladium cluster Pd3{Si(iPr)2}3{P(OCH2)3CEt}3 (6) and Pd{P(OCH2)3CEt}4 in 1:1 molar ratio as products. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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1323 KiB  
Article
Synthesis of a Dichlorodigermasilane: Double Si–Cl Activation by a Ge=Ge Unit
by Tomohiro Sugahara, Norihiro Tokitoh and Takahiro Sasamori
Inorganics 2017, 5(4), 79; https://doi.org/10.3390/inorganics5040079 - 14 Nov 2017
Cited by 7 | Viewed by 4060
Abstract
Halogenated oligosilanes and oligogermanes are interesting compounds in oligosilane chemistry from the viewpoint of silicon-based-materials. Herein, it was demonstrated that a 1,2-digermacyclobutadiene derivative could work as a bis-germylene building block towards double Si–Cl activation to give a halogenated oligometallane, a bis(chlorogermyl)dichlorosilane derivative. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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1975 KiB  
Article
Si–H Bond Activation of a Primary Silane with a Pt(0) Complex: Synthesis and Structures of Mononuclear (Hydrido)(dihydrosilyl) Platinum(II) Complexes
by Norio Nakata, Nanami Kato, Noriko Sekizawa and Akihiko Ishii
Inorganics 2017, 5(4), 72; https://doi.org/10.3390/inorganics5040072 - 25 Oct 2017
Cited by 5 | Viewed by 4527
Abstract
A hydrido platinum(II) complex with a dihydrosilyl ligand, [cis-PtH(SiH2Trip)(PPh3)2] (2) was prepared by oxidative addition of an overcrowded primary silane, TripSiH3 (1, Trip = 9-triptycyl) with [Pt(η2-C2 [...] Read more.
A hydrido platinum(II) complex with a dihydrosilyl ligand, [cis-PtH(SiH2Trip)(PPh3)2] (2) was prepared by oxidative addition of an overcrowded primary silane, TripSiH3 (1, Trip = 9-triptycyl) with [Pt(η2-C2H4)(PPh3)2] in toluene. The ligand-exchange reactions of complex 2 with free phosphine ligands resulted in the formation of a series of (hydrido)(dihydrosilyl) complexes (3–5). Thus, the replacement of two PPh3 ligands in 2 with a bidentate bis(phosphine) ligand such as DPPF [1,2-bis(diphenylphosphino)ferrocene] or DCPE [1,2-bis(dicyclohexylphosphino)ethane] gave the corresponding complexes [PtH(SiH2Trip)(L-L)] (3: L-L = dppf, 4: L-L = dcpe). In contrast, the ligand-exchange reaction of 2 with an excess amount of PMe3 in toluene quantitatively produced [PtH(SiH2Trip)(PMe3)(PPh3)] (5), where the PMe3 ligand is adopting trans to the hydrido ligand. The structures of complexes 2–5 were fully determined on the basis of their NMR and IR spectra, and elemental analyses. Moreover, the low-temperature X-ray crystallography of 2, 3, and 5 revealed that the platinum center has a distorted square planar environment, which is probably due to the steric requirement of the cis-coordinated phosphine ligands and the bulky 9-triptycyl group on the silicon atom. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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1405 KiB  
Article
Preparation and Molecular Structure of a Cyclopentyl-Substituted Cage Hexasilsesquioxane T6 (T = cyclopentyl-SiO1.5) Starting from the Corresponding Silanetriol
by Jürgen Kahr, Ferdinand Belaj and Rudolf Pietschnig
Inorganics 2017, 5(4), 66; https://doi.org/10.3390/inorganics5040066 - 04 Oct 2017
Cited by 8 | Viewed by 3644
Abstract
Cyclopentyl substituted silanetriol can be prepared and isolated. Its condensation yields the corresponding disiloxanetetrol as a primary condensation product. Further condensation leads to the hexameric polyhedral silsesquioxane cage T6. The latter has been mentioned in the literature before however, lacking structural data. All [...] Read more.
Cyclopentyl substituted silanetriol can be prepared and isolated. Its condensation yields the corresponding disiloxanetetrol as a primary condensation product. Further condensation leads to the hexameric polyhedral silsesquioxane cage T6. The latter has been mentioned in the literature before however, lacking structural data. All compounds have been characterized with multinuclear NMR spectroscopy and, in addition, the molecular structures have been determined in the case of the disiloxanetetrol and the hexasilsesquioxane via single crystal X-ray diffraction. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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Review

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2674 KiB  
Review
Modification of TiO2 Surface by Disilanylene Polymers and Application to Dye-Sensitized Solar Cells
by Yohei Adachi, Daiki Tanaka, Yousuke Ooyama and Joji Ohshita
Inorganics 2018, 6(1), 3; https://doi.org/10.3390/inorganics6010003 - 26 Dec 2017
Cited by 7 | Viewed by 3687
Abstract
The surface modification of inorganic materials with organic units is an important process in device preparation. For the modification of TiO2, organocarboxylic acids (RCO2H) are usually used. Carboxylic acids form ester linkages (RCO2Ti) with hydroxyl groups on [...] Read more.
The surface modification of inorganic materials with organic units is an important process in device preparation. For the modification of TiO2, organocarboxylic acids (RCO2H) are usually used. Carboxylic acids form ester linkages (RCO2Ti) with hydroxyl groups on the TiO2 surface to attach the organic groups on the surface. However, the esterification liberates water as a byproduct, which may contaminate the surface by affecting TiO2 electronic states. In addition, the ester linkages are usually unstable towards hydrolysis, which causes dye detachment and shortens device lifetime. In this review, we summarize our recent studies of the use of polymers composed of disilanylene and π-conjugated units as new modifiers of the TiO2 surface. The TiO2 electrodes modified by those polymers were applied to dye-sensitized solar cells. Full article
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
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