Das unterschiedliche Reaktionsverhalten von basefreiem Tris(trimethylsilyl)methyl-Lithium gegenüber den Trihalogeniden der Erdmetalle und des Eisens

Abstract

Professor Josef Goubeau in memoriamInhaltsu È bersicht. Basefreies Tris(trimethylsilyl)methyl-Lithium, Tsi±Li, reagiert mit den Trihalogeniden der Erdmetalle (MHal 3 mit M = Al, Ga, In und Hal = Cl, Br, I) prima È r unter Bildung der Metallate [Tsi±MHal 3 ]Li. Vor allem mit den schwereren Halogeniden von Ga und In findet aber mit u È berschu È ssigem Tsi±Li zusa È tzlich zur simplen Metathese gleichzeitig auch eine Methylierung statt, die in unterschiedlichem Maûe die Mono-und Dimethylverbindungen Tsi±M(Me)Hal (M = Ga, In; Hal = I), Tsi±MMe 2 (M = Ga) bzw. das Bis-(trisyl)derivat (Tsi) 2 InMe sowie stets als Nebenprodukt noch 1,3-Disilacyclobutan ergibt. Durch mehrma-lige, fraktionierende Kristallisationen oder Sublimationen konnten Vertreter dieser Verbindungstypen aus den Reaktionsmischungen isoliert und mit spektroskopischen Methoden ( 1 H, 13 C, 29 Si-NMR; IR, Raman) sowie zum Teil ro È ntgenographisch charakterisiert werden. FeCl 3 reagiert mit Tsi±Li (Verha È ltnis 1 : 3) in Toluol bei 55±60°C unter Reduktion, wobei rotviolettes Fe(Tsi) 2 , 1,1,1-Tris(trimethylsilyl)-2-phenylethan und geringe Mengen an Tsi±Cl gebildet werden. Fe(Tsi) 2 ist monomer, kristallisiert in der monoklinen Raumgruppe C2/c und hat ein lineares C±Fe±C-Skelett mit Fe±C-Bindungsabsta È nden von 204,5(4) pm.Abstract. Base-free tris(trimethylsilyl)methyl Lithium, Tsi±Li, reacts with the earth-metal trihalogenides (MHal 3 with M = Al, Ga, In and Hal = Cl, Br, I) primarily to give the metallates [Tsi±MHal 3 ]Li. Simultaneous to this simple metathesis a methylation also takes place, mainly with heavier halogenides of Ga and In with excess Tsi±Li, forming the mono and dimethyl compounds Tsi±M(Me)Hal (M = Ga, In; Hal = I), Tsi±MMe 2 (M = Ga), and the bis(trisyl)derivative (Tsi) 2 InMe, respectively and the main by-product 1,3-disilacyclobutane. Representatives of each type of compound have been isolated by fractionating crystallizations or subli-mations and characterized by spectroscopic methods ( 1 H, 13 C, 29 Si NMR, IR, Raman) and X-ray elucidations. Reduction takes place, when FeCl 3 reacts with Tsi±Li (1 : 3 ratio) in toluene at 55±60°C, yielding red-violet Fe(Tsi) 2 , 1,1,1-tris-(trimethylsilyl)-2-phenyl ethane and low amounts of Tsi±Cl. Fe(Tsi) 2 is monomeric, crystallizes in the monoclinic space group C2/c and consists of a linear C±Fe±C skeleton with d(Fe±C) of 204,5(4) pm.

Ferromagnetic Coupling in an Fe[C(SiMe3)3]2/Ferrihydrite Hetero‐Mixture Molecular Magnet

“…All DFT calculations were carried out with the program package ORCA 2.8 28. The calculated structure reproduces well those experimentally determined by XRD analyses12 as well as by single‐crystal X‐ray analyses 13. The derived electron density for the Fe[C(SiMe 3 ) 3 ] 2 , as predicted by theory, is illustrated in Figure 1 (b).…”

“…Thus, as highlighted recently in the literature,11 maximizing the height of the spin‐reversal barrier U by focusing only on maximizing S T , represents a somewhat limiting approach towards future implementation of such molecules in functional devices. Looking at the known SIMM systems containing d‐block metal ions reported in the literature, the two‐coordinate (C–Fe–C) linear molecule Fe[C(SiMe 3 ) 3 ] 2 certainly represents the archetype of the intriguing examples in which it is observed as an unusual metal coordination motif, see Figure 1 (a) 12,13…”

“… (a) The X‐ray structure of Fe[C(SiMe 3 ) 3 ] 2 showing the linear C–Fe–C coordination motif (CCDC‐152530) 13. (b) The calculated electron density of Fe[C(SiMe 3 ) 3 ] 2 predicted by density functional theory [B3LYP/CP(PPP)/TZVP] as obtained from the optimized geometry.…”

A linear cobalt(II) complex with maximal orbital angular momentum from a non-Aufbau ground state

“…1, B and C). The Co-C and Zn-C interatomic distances of 2.066(2) and 1.995(3) Å, respectively, are similar to the Fe-C separation of 2.0505( 14) Å in Fe(C(SiMe 3 ) 3 ) 2 (12) and the Zn-C separation of 1.982(2) Å in Zn(C(SiMe 3 ) 3 ) 2 (21). In addition, the Co•••O distance of 3.1051(11) Å and the Zn•••O distance of 3.1240(16) Å are substantially longer than the sum of cobalt or zinc and oxygen ionic radii (~2.2 Å), suggesting minimal interactions.…”

DFT Study of the Reaction of a Two-Coordinate Iron(II) Dialkyl Complex with Molecular Oxygen

“…2,5 A two-coordinate iron complex with the bulky tris(trimethylsilyl)methyl ligand, {Fe[C(SiMe 3 ) 3 ] 2 }, was reported by Locke and co-workers. 1 Power et al reported the unexpected stability of another homoleptic two-coordinate complex, {Fe[OC 6 H 3 -2,6-(C 6 H 3 -2,6-i Pr 2 ) 2 ]}. Amazingly, the latter complex was prepared directly from Fe(C 6 H 3 -2,6-(C 6 H 3 -2,6-( i Pr 2 ) 2 ) 2 and O 2 !…”