Distannabarrelenes with Three Coordinated Sn^II Atoms

Abstract

Crystalline 1,4‐distannabarrelene compounds [(ADCAr)3Sn2]SnCl3 (3‐Ar) (ADCAr={ArC(NDipp)2CC}; Dipp=2,6‐iPr2C6H3, Ar=Ph or DMP; DMP=4‐Me2NC6H4) derived from anionic dicarbenes Li(ADCAr) (2‐Ar) (Ar=Ph or DMP) have been reported. The cationic moiety of 3‐Ar features a barrelene framework with three coordinated SnII atoms at the 1,4‐positions, whereas the anionic unit SnCl3 is formally derived from SnCl2 and chloride ion. The all carbon substituted bis‐stannylenes 3‐Ar have been characterized by NMR spectroscopy and X‐ray diffraction. DFT calculations reveal that the HOMO of 3‐Ph (ϵ=−6.40 eV) is mainly the lone‐pair orbital at the SnII atoms of the barrelene unit. 3‐Ar readily react with sulfur and selenium to afford the mixed‐valence SnII/SnIV compounds [(ADCAr)3SnSn(E)](SnCl6)0.5 (E=S 4‐Ar, Ar=Ph or DMP; E=Se 5‐Ph).

An Open‐Shell Singlet SnI Diradical and H2 Splitting

“…Treatment of a freshly prepared solution of 2 with (DMAP)SnCl 2 (DMAP=Me 2 NC 5 H 4 N) led to the formation of the anticipated bis‐chlorostannylene 3 in 73 % yield as a colorless crystalline solid. It should be noted that the use of (DMAP)SnCl 2 is essential to selectively prepare 3 as the reaction of 2 with SnCl 2 , irrespective of the ratio, almost exclusively gives [(ADC Ph ) 3 Sn 2 ]SnCl 3 ( IV ) [15] …”

“…Thus, in addition to kinetic stabilization using bulky substituents, the use of new electron-rich ligands seems desirable in accessing stable heavier benzene derivatives. [14] We recently prepared barrelene type Sn II compounds (IV) [15] based on an anionic dicarbene (ADC Ar ) [16] (ADC Ar = {CN(Dipp)} 2 CAr; Ar = aryl; Dipp = 2,6-iPr 2 C 6 H 3 ) and subsequently decided to probe the synthetic viability of corresponding 1,4-distannabenzene derivatives. Herein, we report the first example of a Sn I compound [(ADC Ph )Sn] 2 (4) containing a C 4 Sn 2 ring and describe its electronic structure and reactivity (Scheme 1).…”

“…It should be noted that the use of (DMAP)SnCl 2 is essential to selectively prepare 3 as the reaction of 2 with SnCl 2 , irrespective of the ratio, almost exclusively gives [(ADC Ph ) 3 Sn 2 ]SnCl 3 (IV). [15] Compound 3 was characterized by NMR and X-ray diffraction ( Figure 2). KC 8 reduction of 3 led to the formation of compound 4 (see the Supporting Information), which was isolated as a green crystalline solid in 93 % yield.…”

Ein offenschaliges Singulett‐SnI‐Diradikal und H2‐Spaltung

“…Daher empfiehlt sich für den Zugang zu Verbindungen dieses Typs neben kinetischer Stabilisierung durch sperrige Substituenten auch die Verwendung innovativer elektronenreicher Liganden. [14] Wir haben kürzlich Sn II -Verbindungen vom Barrelentyp (IV) [15] auf Basis eines anionischen Dicarbens (ADC Ar ) [16] (ADC Ar = {CN(Dipp)} 2 CAr; Ar = Aryl; Dipp = 2,6-iPr 2 [15] Verbindung 3 wurde durch NMR und Rçntgenbeugung charakterisiert (Abbildung 2). Die KC 8 -Reduktion von 3 führte zur Bildung von Verbindung 4 (siehe Hintergrundinformationen), die als grüner, kristalliner Feststoff in 93 % Ausbeute isoliert wurde.…”

“…Die Sn-C2/C3#-Bindungslängen von 4 (2.202(3) und 2.205(3) ) sind etwas kleiner als die von 3 (2.229 1, (2.234-(1) ), IV (2.24 bis 2.27 ) [15] und der Sn 0 -Verbindung (IPr) 2 Sn 2 von Jones (2.297 ), [19] übertreffen jedoch die Sn-C-Bindungslänge in den Stannabenzol-Derivaten II und III (2.02-2.08 ) ) mit formalen Sn 3+ -Zentren [11d,j] sowie die Sn= C-Bindungslängen von Stannenen (2.00-2.07 ). [20] Es sollte jedoch beachtet werden, dass die Bindungen in niedervalenten Verbindungen immer länger sind als die von verwandten hçhervalenten Derivaten, da die Bindungsorbitale in Ersteren einen geringeren s-Charakter aufweisen.…”