An Open‐Shell Singlet SnI Diradical and H2 Splitting

• Published in: Angewandte Chemie International Edition 2021-03, Vol.60 (12), p.6414-6418
• Main Authors: Sharma, Mahendra K., Rottschäfer, Dennis, Glodde, Timo, Neumann, Beate, Stammler, Hans‐Georg, Ghadwal, Rajendra S.
• Format: Article
• Language: English
• Subjects: aromaticity; Communication; Communications; diradical; distannabenzene; Energy gap; H2 splitting; Mathematical analysis; open-shell systems; Ring currents; Room temperature
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202017078

The first SnI diradical [(ADCPh)Sn]2 (4) based on an anionic dicarbene (ADCPh={CN(Dipp)}2CPh; Dipp=2,6‐iPr2C6H3) scaffold has been isolated as a green crystalline solid by KC8 reduction of the corresponding bis‐chlorostannylene [(ADCPh)SnCl]2 (3). The six‐membered C4Sn2‐ring of 4 containing six π‐electrons shows a diatropic ring current, thus 4 may also be regarded as the first 1,4‐distannabenzene derivative. DFT calculations suggest an open‐shell singlet (OS) ground state of 4 with a remarkably small singlet–triplet energy gap (ΔEOS–T=4.4 kcal mol−1), which is consistent with CASSCF (ΔES–T=6.6 kcal mol−1 and diradical character y=37 %) calculations. The diradical 4 splits H2 at room temperature to yield the bis‐hydridostannylene [(ADCPh)SnH]2 (5). Further reactivity of 4 has been studied with PhSeSePh and MeOTf. A 1,4‐distannabenzene derivative 4 with two‐coordinated SnI atoms has been isolated as a green crystalline solid. The ground state of 4 is an open‐shell singlet (OS) with the singlet–triplet energy gap (ΔEOS–T) of 4.4 kcal mol−1 (according to CASSCF, ΔES–T=6.6 kcal mol−1). Consequently, 4 exhibits a half‐field EPR signal at 100 K and undergoes H2 splitting at room temperature to quantitatively yield the SnII hydride 5 as an orange solid.