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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and spectroscopic properties of bis(trimethylsilyl)amides the alkaline-earth metals magnesium, calcium, strontium, bariumMatthias WesterhausenCite this: Inorg. Chem. 1991, 30, 1, 96–101Publication Date (Print):January 1991Publication History Published online1 May 2002Published inissue 1 January 1991https://pubs.acs.org/doi/10.1021/ic00001a018https://doi.org/10.1021/ic00001a018research-articleACS PublicationsRequest reuse...
A novel and efficient calcium alkoxide initiating system, generated in situ from bis(tetrahydrofuran)calcium bis[bis(trimethylsilyl)amide] an alcohol, for the ring-opening polymerization of cyclic esters has been developed. The solution THF using mild conditions is living, yielding polyesters controlled molecular weight tailored macromolecular architecture. polymerizations initiated with 2-propanol−Ca[N(SiMe3)2]2(THF)2 system are first-order monomer no induction period. At high...
Abstract Das aus Lithium‐dihydrogenphosphid. DME( 1 ) und Ethylformiat im Molverhältnis 2 : mit 87 proz. Ausbeute isolierte, flüssige Lithium‐formylphosphid. DME liegt als Lithoxy‐methylidenphosphan. ( einem an den Sauerstoff der Carbonylgruppe gebundenen, DME‐komplexierten Lithium vor. Nach Röntgenstrukturanalysen kristallinen Derivaten [5, 6] dimerisieren Verbindungen dieses Typs unter Ausbildung eines viergliedrigen LiOLiO‐Ringes; die Auswertung NMR‐Spektren ergibt für PC‐Gruppe E‐...
Compounds of the type aryl--M--X, with M=Ca, Sr, Ba and X as any kind ligand (such halide, phosphanide, amide, aryl), are presented. The low reactivity heavy alkaline earth metals calcium, strontium, barium enforces an activation prior to use for direct synthesis. insertion these into C--I bonds aryl iodides (direct synthesis) yields metal has be performed at temperatures in THF. Aryl alkaline-earth-metal compounds show some characteristics: 1) ease ether cleavage reaction temperatures, 2)...
The reaction of bromo-2,4,6-triphenylbenzene with activated magnesium in THF yielded the Grignard reagent [(thf)2Mg(Br)-C6H2-2,4,6-Ph3] (1) a Mg−C bond length 214.8(3) pm. A similar calcium led to an "inverse" sandwich complex [(thf)3Ca{μ-C6H3-1,3,5-Ph3}Ca(thf)3] (2) atoms on opposite sides central arene ring showing small Ca−Ca′ and Ca−C distances 427.9(3) 259.2(3) This extremely air- moisture-sensitive exhibits thermochomic solvatochromic behavior. It is paramagnetic spin S = 1 (triplet)...
Abstract The organocalcium chemistry developed vastly during the last decade. preparation of compounds via direct synthesis (insertion Ca into a C‐X bond phenyl halides, Grignard reaction) affords skilful procedures due to inertia calcium metal and extreme reactivity derivatives. Further suitable preparative methods include metathesis reactions CaX 2 with KR or LiR, metallation H‐acidic substrates, metal‐halogen exchange reactions, transmetallation heavy main group atoms in their metal....
Heterobimetallic compounds of the alkaline-earth metals show a wide structural variety with strongly differing reactivity patterns. The combination magnesium and alkali metal amides yields cyclic molecules an extreme high which often are considered as "inverse crowns" atoms coordination sites for Lewis bases. In other metallates activation alkyl groups succeeds. zincates inverse type M(2)[(mu-R)(2)ZnR](2) is observed in bridging positions between zinc s-block thus forming very reactive...
Organocalcium chemistry is still in its infancy. The direct synthesis of activated calcium and (substituted) iodobenzenes allows for the large-scale high-yield aryl iodides. influence substitution patterns phenyl group, halogen atom, solvent discussed. Aryl iodides show a Schlenk equilibrium that enables isolation diaryl derivatives. Owing to high reactivity halides, low temperatures have be maintained throughout preparative procedures order avoid side reactions. A decrease and, hence, an...
The in‐situ Grignard addition method (iGAM) adds intermediately prepared organo alkaline‐earth metal halides onto a suitable substrate. Here, freshly rasped calcium and the carbodiimide R’‐N=C=N‐R’ (R’ = SiMe3, iPr) are suspended in THF at room temperature then an organyl halide R‐X (X Br, I) is added. Within several hours, formed R‐Ca‐X yielding corresponding thf adducts of amidinato {(R’N)2C‐R}CaX. Suitable besides aryl iodide methyl ethyl whereas bulkier isopropyl tert‐butyl iodides give...
Even a century after the discovery of Grignard reagents, similar compounds heavy alkaline earth metals are still lacking. Owing to industrial need for such (in particular as anionic polymerization catalysts), last few years have been marked by rapid, extensive development which has culminated in first structurally characterized alkylbarium derivatives crown ether complex bis(triphenylmethyl)barium (1). hmpt=hexamethylphosphoric acid triamide.
Abstract Die Reaktion von Yttrium(III)‐chlorid mit der dreifachen molaren Menge LiE(SiMe 3 ) 2 (E = N, CH) ergibt die entsprechenden Yttrium‐Derivate. Yttrium‐tris[bis(trimethylsilyl)amid] kristallisiert in Raumgruppe P 1c a 1 636,3(2), c 849,3(2) pm, Z 2. Das Yttriumatom ist trigonal pyramidal koordiniert YN‐Bindungslängen 222 pm. Entlang c‐Achse sind Benzolmoleküle eingeschlossen. Verbindung E CH als (Et O) LiCl‐Addukt monoklinen P2 /n 111,8(2), b 865,2(6), 2598,3(9) β 97,41(3)° und 4....
Abstract Die Molekül‐ und Kristallstrukturen des dimeren Calcium‐bis[bis(trimethylsilyl)amids] 1 · DME 2 werden beschrieben. {Ca[N(SiMe 3 ) ] } kristallisiert in der triklinen Raumgruppe P mit {a = 890,9(2); b 1259,3(4); c 2158,8(7) pm; α 88,13(2); β 88,49(2); γ 72,25(2)°; Z 2}. Calciumatome sind dreifach koordiniert CaN t ‐Bindungslängen von 227 pm zu den terminalen Liganden ‐Bindungen 247 verbrückenden Amidogruppen. Ca[N(SiMe aus n ‐Hexan monoklinen C2/c 854,9(3); 1738,2(6); 2042,1(6)...
Abstract The equimolar reaction of calcium bis[bis(trimethylsilyl)amide] with 2,2,6,6‐tetramethylheptane‐3,5‐dione (Htmhd) in THF yields liquid mononuclear [Ca(tmhd){N(SiMe 3 ) 2 }(THF) ] ( 1 ). A similar toluene a stoichiometric ratio 2:3 gives the dinuclear complex [{(THF)Ca} (tmhd) (µ‐tmhd){µ‐N(SiMe }] atoms these complexes are distorted octahedral environment. In consists two octahedra connected by common face one nitrogen base and oxygen atoms; bridging Ca−N bond lengths extremely...
The direct synthesis of activated calcium with aryl halides in tetrahydrofuran (THF) gave the following compounds type RCaX fair to good yields: [MesCaI(THF)4] (1), [(p-tolyl)CaI(THF)4] (2), [PhCaI(THF)4] (3), and [PhCaBr(THF)4] (5). All these "heavy Grignard reagents" contain a atom slightly distorted octahedral environment. They must be handled at low temperatures order avoid ether cleavage reactions. Ca−C bond lengths vary between 2.556(5) Å (3) 2.583(3) thermal stability is enhanced when...
Abstract Das Magnesium‐bis[bis(trimethylsilyl)amid] kristallisiert als Dimeres in der monoklinen Raumgruppe C2/c mit {a = 1821,0(4); b 1494,4(4); c 1859,56(6) pm; β 121,10(2)° Z 4 dimere}. zentrale Strukturelement bildet viergliedrige, planare Mg 2 N ‐Ring endocyclischen NMgN‐Winkeln von 95,8°. Die Bindungslängen innerhalb dieses Ringsystems vom Metallzentrum zum vierfach koordinierten, verbrückend auftretenden Stickstoffatom liegen bei 215 pm, während die Abstände zwischen dem Magnesiumatom...
Two for one: Molecular magnesium(I) compounds (see structure: Mg light blue, N dark C gray) with astonishing stability are now accessible in good yields. Decomposition reactions observed at 170 °C and 300 °C, depending on the ligand present.