s-Block Metal Complexes

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

Deadline for manuscript submissions: closed (31 March 2017) | Viewed by 62385

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Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstrasse 8, D-07743 Jena, Germany
Interests: s-block metal coordination chemistry; catalysis with s-block metals; Grignard reagents; transition metal carbonyl complexes; scorpionates; organocalcium compounds; cooperative effects in heterobimetallic complexes

Special Issue Information

Dear Colleagues,

The coordination chemistry of the s-block metals spans diverse fields, ranging from shielded coordination compounds over hydride to organometallic complexes for diverse applications. New developments pertain, not only to the lithium and magnesium chemistry with inspiring examples, such as heterobimetallic or heteroleptic complexes with special reactivity patterns, but the heavy s-block metals have progressively gained attention in various fields. Subvalent magnesium(I) derivatives are increasingly being used for reduction reactions, turbo-Grignard reagents show enhanced reactivity and tolerance toward functional groups, hydrides act as hydrogen storage materials, heavy Grignard reagents are available by straight forward procedures—just to name a few examples. Quantum chemical calculations deal with unique bonding situations and the relevance of d-orbital participation has been discussed to understand structure-reactivity relationships. Especially the complexes of the heavy alkaline earth metals are catalytically active in diverse reactions, promoting hydrofunctionalization reactions and Lewis acid catalysis. This Special Issue aims to highlight the structural and chemical diversity of s-block metal complexes, as well as the broad field of applications.

Prof. Dr. Matthias Westerhausen
Guest Editor

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Keywords

  • s-block metal coordination compounds
  • Grignard-type reagents
  • Lochmann-Schlosser bases
  • s-block metal-mediated catalysis
  • bonding in s-block complexes
  • heterobimetallic complexes

Published Papers (12 papers)

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Editorial

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447 KiB  
Editorial
Kudos and Renaissance of s-Block Metal Chemistry
by Sven Krieck and Matthias Westerhausen
Inorganics 2017, 5(1), 17; https://doi.org/10.3390/inorganics5010017 - 21 Mar 2017
Cited by 14 | Viewed by 5724
Abstract
In recent years, the organometallic and coordination chemistry of the alkali and alkaline earth metals has experienced tremendous progress to tackle the needs of today’s society. Enhanced ecological awareness and global availability favor research on the chemistry of the essential s-block metals. Nowadays, [...] Read more.
In recent years, the organometallic and coordination chemistry of the alkali and alkaline earth metals has experienced tremendous progress to tackle the needs of today’s society. Enhanced ecological awareness and global availability favor research on the chemistry of the essential s-block metals. Nowadays, the s-block metals are conquering new chemical fields based on sophisticated theoretical and preparative achievements. Recent investigations show a huge impact of the s-block elements on stoichiometric and catalytic processes. Full article
(This article belongs to the Special Issue s-Block Metal Complexes)
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Research

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2433 KiB  
Article
[Bis(Trimethylsilyl)Methyl]Lithium and -Sodium: Solubility in Alkanes and Complexes with O- and N- Donor Ligands
by Markus Von Pilgrim, Mihail Mondeshki and Jan Klett
Inorganics 2017, 5(2), 39; https://doi.org/10.3390/inorganics5020039 - 12 Jun 2017
Cited by 8 | Viewed by 5739
Abstract
In contrast to alkyl compounds of lithium, which play an important role in organometallic chemistry, the corresponding heavier alkali metal compounds are less investigated. These compounds are mostly insoluble in inert solvents or undergo solvolysis in coordinating solvents due to their high reactivity. [...] Read more.
In contrast to alkyl compounds of lithium, which play an important role in organometallic chemistry, the corresponding heavier alkali metal compounds are less investigated. These compounds are mostly insoluble in inert solvents or undergo solvolysis in coordinating solvents due to their high reactivity. An exception from this typical behavior is demonstrated by bis(trimethylsilyl)methylsodium. This study examines alkane solutions of bis(trimethylsilyl)methyllithium and -sodium by NMR spectroscopic and cryoscopic methods. In addition, structural studies by X-ray crystallography of the corresponding compounds coordinated by O- and N- ligands (tetrahydrofuran and tetramethylethylenediamine) present possible structural motifs of the uncoordinated compounds in solution. Full article
(This article belongs to the Special Issue s-Block Metal Complexes)
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2792 KiB  
Article
Symmetric Assembly of a Sterically Encumbered Allyl Complex: Mechanochemical and Solution Synthesis of the Tris(allyl)beryllate, K[BeA′3] (A′ = 1,3-(SiMe3)2C3H3)
by Nicholas C. Boyde, Nicholas R. Rightmire, Timothy P. Hanusa and William W. Brennessel
Inorganics 2017, 5(2), 36; https://doi.org/10.3390/inorganics5020036 - 27 May 2017
Cited by 15 | Viewed by 4884
Abstract
The ball milling of beryllium chloride with two equivalents of the potassium salt of bis(1,3-trimethylsilyl)allyl anion, K[A′] (A′ = [1,3-(SiMe3)2C3H3]), produces the tris(allyl)beryllate K[BeA’3] (1) rather than the expected neutral BeA’ [...] Read more.
The ball milling of beryllium chloride with two equivalents of the potassium salt of bis(1,3-trimethylsilyl)allyl anion, K[A′] (A′ = [1,3-(SiMe3)2C3H3]), produces the tris(allyl)beryllate K[BeA’3] (1) rather than the expected neutral BeA’2. The same product is obtained from reaction in hexanes; in contrast, although a similar reaction conducted in Et2O was previously shown to produce the solvated species BeA’2(OEt2), it can produce 1 if the reaction time is extended (16 h). The tris(allyl)beryllate is fluxional in solution, and displays the strongly downfield 9Be NMR shift expected for a three-coordinate Be center (δ22.8 ppm). A single crystal X-ray structure reveals that the three allyl ligands are bound to beryllium in an arrangement with approximate C3 symmetry (Be–C (avg) = 1.805(10) Å), with the potassium cation engaging in cation–π interactions with the double bonds of the allyl ligands. Similar structures have previously been found in complexes of zinc and tin, i.e., M[M′A′3L] (M′ = Zn, M = Li, Na, K; M′ = Sn, M = K; L = thf). Density functional theory (DFT) calculations indicate that the observed C3-symmetric framework of the isolated anion ([BeA′3]) is 20 kJ·mol−1 higher in energy than a C1 arrangement; the K+ counterion evidently plays a critical role in templating the final conformation. Full article
(This article belongs to the Special Issue s-Block Metal Complexes)
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3293 KiB  
Article
Hetero- and Homoleptic Magnesium Triazenides
by Denis Vinduš and Mark Niemeyer
Inorganics 2017, 5(2), 33; https://doi.org/10.3390/inorganics5020033 - 01 May 2017
Cited by 4 | Viewed by 4464
Abstract
Using monoanionic triazenide ligands derived from biphenyl and m-terphenyl substituted triazenes Dmp(Tph)N3H (1a), (Me4Ter)2N3H (1b) or Dmp(Mph)N3H (1c) (Dmp = 2,6-Mes2C6H3 with Mes = 2,4,6-Me3C6H2; Me4Ter = 2,6-(3,5-Me2C6H3)2C6H3; Mph = 2-MesC6H4; Tph = 2-TripC6H4 with Trip = 2,4,6-i-Pr3C6H2), several magnesium triazenides were synthesized. [...] Read more.
Using monoanionic triazenide ligands derived from biphenyl and m-terphenyl substituted triazenes Dmp(Tph)N3H (1a), (Me4Ter)2N3H (1b) or Dmp(Mph)N3H (1c) (Dmp = 2,6-Mes2C6H3 with Mes = 2,4,6-Me3C6H2; Me4Ter = 2,6-(3,5-Me2C6H3)2C6H3; Mph = 2-MesC6H4; Tph = 2-TripC6H4 with Trip = 2,4,6-i-Pr3C6H2), several magnesium triazenides were synthesized. Heteroleptic complexes [Mg(N3Ar2)I(OEt2)] (Ar2 = Dmp/Tph (2a), (Me4Ter)2 (2b) were obtained from metalation of the corresponding triazenes with di-n-butylmagnesium followed by reaction with iodine in diethyl ether as the solvent in high yields. Replacing diethyl ether by n-heptane afforded trinuclear compounds [Mg3(N3Ar2)2I4] (3a, 3b) in low yields in which a central MgI2 fragment is coordinated by two iodomagnesium triazenide moieties. Two unsolvated homoleptic magnesium compounds [Mg(N3Ar2)2] (4b, 4c) were obtained from di-n-butylmagnesium and triazenes 1b or 1c in a 1:2 ratio. Depending on the nature of the substituents, the magnesium center either shows the expected tetrahedral or a rather unusual square planar coordination. Full article
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6358 KiB  
Article
Backbone-Substituted β-Ketoimines and Ketoiminate Clusters: Transoid Li2O2 Squares and D2-Symmetric Li4O4 Cubanes. Synthesis, Crystallography and DFT Calculations
by Twyla Gietz and René T. Boeré
Inorganics 2017, 5(2), 30; https://doi.org/10.3390/inorganics5020030 - 26 Apr 2017
Cited by 7 | Viewed by 5329
Abstract
The preparation and crystal structures of four β-ketoimines with bulky aryl nitrogen substituents (2,6-diisopropylphenyl and 2,4,6-trimethylphenyl) and varying degrees of backbone methyl substitution are reported. Backbone substitution “pinches” the chelate ring. Deprotonation with n-butyllithium leads to dimeric Li2O2 clusters, [...] Read more.
The preparation and crystal structures of four β-ketoimines with bulky aryl nitrogen substituents (2,6-diisopropylphenyl and 2,4,6-trimethylphenyl) and varying degrees of backbone methyl substitution are reported. Backbone substitution “pinches” the chelate ring. Deprotonation with n-butyllithium leads to dimeric Li2O2 clusters, as primary laddered units, with an open transoid geometry as shown by crystal structures of three examples. The coordination sphere of each lithium is completed by one tetrahydrofuran ligand. NMR spectra undertaken in either C6D6 or 1:1 C6D6/d8-THF show free THF in solution and the chemical shifts of ligand methyl groups experience significant ring-shielding which can only occur from aryl rings on adjacent ligands. Both features point to conversion to higher-order aggregates when the THF concentration is reduced. Recrystallization of the materials from hydrocarbon solutions results in secondary laddering as tetrameric Li4O4 clusters with a cuboidal core, three examples of which have been crystallographically characterised. These clusters are relatively insoluble and melt up to 250 °C; a consideration of the solid-state structures indicates that the clusters with 2,6-diisopropylphenyl substituents form very uniform ball-like molecular structures that will only be weakly solvated. Full article
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3775 KiB  
Article
Methanediide Formation via Hydrogen Elimination in Magnesium versus Aluminium Hydride Complexes of a Sterically Demanding Bis(iminophosphoranyl)methanediide
by Christian P. Sindlinger, Samuel R. Lawrence, David B. Cordes, Alexandra M. Z. Slawin and Andreas Stasch
Inorganics 2017, 5(2), 29; https://doi.org/10.3390/inorganics5020029 - 22 Apr 2017
Cited by 4 | Viewed by 4597
Abstract
Substituted bis(iminophosphoranyl)methanes are CH acidic compounds that can form complexes with formally dianionic central carbon centres. The reaction of H2C(Ph2P=NDip)2 (≡ H2L), Dip = 2,6-diisopropylphenyl, with one equivalent of di-n-butylmagnesium afforded the methanide complex [...] Read more.
Substituted bis(iminophosphoranyl)methanes are CH acidic compounds that can form complexes with formally dianionic central carbon centres. The reaction of H2C(Ph2P=NDip)2 (≡ H2L), Dip = 2,6-diisopropylphenyl, with one equivalent of di-n-butylmagnesium afforded the methanide complex [HLMgnBu] 1. Treatment of Complex 1 with phenylsilane in aromatic solvents at elevated temperatures afforded the methanediide complex [(LMg)2] 2 presumably via the MgH intermediate [(HLMgH)n] (n = 1 or 2). The reaction of 1 with LiAlH4 in diethyl ether yielded the AlH complex [HLAlH2] 3. Alternatively, this complex was also obtained from the reaction of H2L with AlH3∙NMe3. The molecular structures of [HLMgnBu] 1, [(LMg)2] 2, and [HLAlH2] 3 are reported. Complex 3 shows no sign of H2 elimination to a methanediide species at elevated temperatures in contrast to the facile elimination of the putative reaction intermediate [(HLMgH)n] (n = 1 or 2) to form [(LMg)2] 2. The chemical properties of Complex 2 were investigated, and this complex appears to be stable against coordination with strong donor molecules. Full article
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1841 KiB  
Article
Alkali and Alkaline Earth Metal Complexes Ligated by an Ethynyl Substituted Cyclopentadienyl Ligand
by Tim Seifert and Peter W. Roesky
Inorganics 2017, 5(2), 28; https://doi.org/10.3390/inorganics5020028 - 20 Apr 2017
Cited by 6 | Viewed by 5005
Abstract
Sodium, potassium, and calcium compounds of trimethyl((2,3,4,5-tetramethylcyclopentadien-1-yl)ethynyl)silane (CpMe4(C≡CSiMe3)) were synthesized and characterized by X-ray diffraction and standard analytical methods. The sodium derivative was obtained by deprotonation of CpMe4(C≡CSiMe3)H with Na{N(SiMe3)2} to [...] Read more.
Sodium, potassium, and calcium compounds of trimethyl((2,3,4,5-tetramethylcyclopentadien-1-yl)ethynyl)silane (CpMe4(C≡CSiMe3)) were synthesized and characterized by X-ray diffraction and standard analytical methods. The sodium derivative was obtained by deprotonation of CpMe4(C≡CSiMe3)H with Na{N(SiMe3)2} to give a monomeric complex [NaCpMe4(C≡CSiMe3)(THF)3]. In a similar reaction, starting from K{N(SiMe3)2} the corresponding potassium compound [KCpMe4(C≡CSiMe3)(THF)2]n, which forms a polymeric super sandwich structure in the solid state, was obtained. Subsequently, salt metathesis reactions were conducted in order to investigate the versatility of the CpMe4(C≡CSiMe3) ligand in alkaline earth chemistry. The reaction of [KCpMe4(C≡CSiMe3)(THF)2]n with CaI2 afforded the dimeric complex [CaCpMe4(C≡CSiMe3)I(THF)2]2, in which both CpMe4(C≡CSiMe3)Ca units are bridged by iodide in a μ2 fashion. In-depth NMR investigation indicates that [CaCpMe4(C≡CSiMe3)I(THF)2]2 is in a Schlenk equilibrium with [{CpMe4(C≡CSiMe3)}2Ca(THF)x] and CaI2(THF)2, as is already known for [CaCp*I(THF)2]. Full article
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2724 KiB  
Article
Potassium C–F Interactions and the Structural Consequences in N,N′-Bis(2,6-difluorophenyl)formamidinate Complexes
by Daniel Werner, Glen B. Deacon and Peter C. Junk
Inorganics 2017, 5(2), 26; https://doi.org/10.3390/inorganics5020026 - 17 Apr 2017
Viewed by 4132
Abstract
Treatment of K[N(SiMe3)2] with N,N′-bis(2,6-difluorophenyl)formamidine (DFFormH) in toluene, resulted in the formation of [K(DFForm)]∞ (1) as a poorly soluble material. Upon dissolution in thf and layering with n-hexane, 1 was crystallised and identified as a two-dimensional polymer, in which all fluorine and nitrogen [...] Read more.
Treatment of K[N(SiMe3)2] with N,N′-bis(2,6-difluorophenyl)formamidine (DFFormH) in toluene, resulted in the formation of [K(DFForm)]∞ (1) as a poorly soluble material. Upon dissolution in thf and layering with n-hexane, 1 was crystallised and identified as a two-dimensional polymer, in which all fluorine and nitrogen atoms, and also part of one aryl group, bridge between four symmetry equivalent potassium ions, giving rise to a completely unique μ4-(N,N′,F,F′):(N,N′):η4(Ar-C(2,3,4,5,6)):(F″,F′′′) DFForm coordination. The two-dimensional nature of the polymer could be deconstructed to one dimension by crystallisation from neat thf at −35 °C, giving [K2(DFForm)2(thf)2]∞ (2), where the thf molecules bridge the monomeric units. Complete polymer dissociation was observed when 1 was crystallised from toluene/n-hexane mixtures in the presence of 18-crown-6, giving [K(DFForm)(18-crown-6)] (3), which showed unprecedented κ(N,Cispo,F) DFForm coordination, rather than the expected κ(N,N′) coordination. Full article
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1703 KiB  
Article
Insights into Molecular Beryllium–Silicon Bonds
by Dominik Naglav, Briac Tobey, Kevin Dzialkowski, Georg Jansen, Christoph Wölper and Stephan Schulz
Inorganics 2017, 5(2), 22; https://doi.org/10.3390/inorganics5020022 - 10 Apr 2017
Cited by 6 | Viewed by 4646
Abstract
We present the synthesis of two silyl beryllium halides HypSiBeX∙(thf) (HypSi = Si(SiMe3)3, X = Cl 2a, I 4a) and the molecular structure of 2a as determined by single crystal X-ray diffraction. Compounds 2a and 4a were characterized via multi-nuclear NMR spectroscopy (1H, [...] Read more.
We present the synthesis of two silyl beryllium halides HypSiBeX∙(thf) (HypSi = Si(SiMe3)3, X = Cl 2a, I 4a) and the molecular structure of 2a as determined by single crystal X-ray diffraction. Compounds 2a and 4a were characterized via multi-nuclear NMR spectroscopy (1H, 9Be, 13C, 29Si), and the bonding situation was further investigated using quantum chemical calculations (with the addition of further halides X = F 1b, Cl 2b, Br 3b, I 4b). The nature of the beryllium silicon bond in the context of these compounds is highlighted and discussed. Full article
(This article belongs to the Special Issue s-Block Metal Complexes)
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2948 KiB  
Article
K+···Cπ and K+···F Non-Covalent Interactions in π-Functionalized Potassium Fluoroalkoxides
by Sorin-Claudiu Roşca, Hanieh Roueindeji, Vincent Dorcet, Thierry Roisnel, Jean-François Carpentier and Yann Sarazin
Inorganics 2017, 5(1), 13; https://doi.org/10.3390/inorganics5010013 - 07 Mar 2017
Cited by 6 | Viewed by 4139
Abstract
Secondary interactions stabilize coordinatively demanding complexes of s-block metals [...] Full article
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2025 KiB  
Article
Structural Study of Mismatched Disila-Crown Ether Complexes
by Kirsten Reuter, Fabian Dankert, Carsten Donsbach and Carsten Von Hänisch
Inorganics 2017, 5(1), 11; https://doi.org/10.3390/inorganics5010011 - 09 Feb 2017
Cited by 18 | Viewed by 7815
Abstract
Mismatched complexes of the alkali metals cations Li+ and Na+ were synthesized from 1,2-disila[18]crown-6 (1 and 2) and of K+ from 1,2,4,5-tetrasila[18]crown-6 (4). In these alkali metal complexes, not all crown ether O atoms participate in [...] Read more.
Mismatched complexes of the alkali metals cations Li+ and Na+ were synthesized from 1,2-disila[18]crown-6 (1 and 2) and of K+ from 1,2,4,5-tetrasila[18]crown-6 (4). In these alkali metal complexes, not all crown ether O atoms participate in the coordination, which depicts the coordination ability of the C-, Si/C-, and Si-bonded O atoms. Furthermore, the inverse case—the coordination of the large Ba2+ ion by the relatively small ligand 1,2-disila[15]crown-5—was investigated, yielding the dinuclear complex 5. This structure represents a first outlook on sandwich complexes based on hybrid crown ethers. Full article
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2339 KiB  
Article
Synthesis and Characterization of a Sulfonyl- and Iminophosphoryl-Functionalized Methanide and Methandiide
by Kai-Stephan Feichtner and Viktoria H. Gessner
Inorganics 2016, 4(4), 40; https://doi.org/10.3390/inorganics4040040 - 02 Dec 2016
Cited by 11 | Viewed by 4337
Abstract
The synthesis of [H2C(PPh2=NSiMe3)(SO2Ph)] (1) and its mono- and dimetalation are reported. Due to the strong anion-stabilizing abilities of the iminophosphoryl and the sulfonyl group monometalation to 1-K and dimetalation to 1-Li2 [...] Read more.
The synthesis of [H2C(PPh2=NSiMe3)(SO2Ph)] (1) and its mono- and dimetalation are reported. Due to the strong anion-stabilizing abilities of the iminophosphoryl and the sulfonyl group monometalation to 1-K and dimetalation to 1-Li2 proceed smoothly with potassium hydride and methyllithium, respectively. Both compounds could be isolated in high yields and were characterized by NMR spectroscopy as well as XRD analysis. The methanide 1-K forms a coordination polymer in the solid state, while in case of the methandiide a tetrameric structure is observed. The latter features an unusual structural motif consisting of two (SO2Li)2 eight-membered rings, which are connected with each other via the methandiide carbon atoms and additional lithium atoms. With increasing metalation a contraction of the P–C–S linkage is observed, which is well in line with the increased charge at the central carbon atom and involved electrostatic interactions. Full article
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