An Open‐Shell Singlet Sn^I Diradical and H₂ Splitting

Abstract

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.

Distannadithiophenes and Their Application towards Hydroboration of Carbonyl Compounds

“…The Sn−C bond distances fall in the range of 2.119 (2) Å to 2.156 (2) Å, comparable with the values reported in the literature especially with distannaanthracene molecules reported by Saito group [3b,10a–b] . However, the Sn−C bond distances are shorter than the low‐valent tin dimers reported by Ghadwal and co‐workers [10d,e] . The endo cyclic C−Sn‐C angles are 108.6(2) ° for 3 ; 109.3(2) ° for 4 and 110.4(2) ° for 6 are comparable with distannaanthracene molecules reported by Saito group [10a,c] …”

Recent advances in stable main group element radicals: preparation and characterization

“…The isolation of diradicaloids Ge-N5 and Sn-N2, possessing a 6p-electron C 4 E 2 framework, was achieved via the treatment of Ge-PN5 or Sn-PN2 with two equivalents of potassium graphite in THF and almost quantitatively isolated as a red crystalline solid, respectively (Scheme 55). 87,88 X-ray crystallography suggests the delocalization of the 6p-electrons over the C 4 E 2 six-membered ring (Fig. 15).…”

“…Ellipsoids represent 50% probability and all hydrogen atoms have been omitted for clarity. 87,88 Scheme 56 Synthesis of germanium radical Ge-A1.…”

An Acyclic Diaminocarbene Complex of Platinum Formed by Desulfurization of 1,3‐Bis(3‐methylpyridin‐2‐yl)thiourea

“…Compared to NHCs which are widely used as components of catalysts, ADCs generally have a stronger σ donor character and a wider NÀ CÀ N angle, allowing for a closer approach of a coordinated metal center to provide better steric control. [1,2] Catalytic applications of palladium-and platinumÀ ADCs in intermolecular Heck, [3][4][5] Buchwald-Hartwig, Sonogashira and Suzuki-Miyaura cross-coupling and several intramolecular cyclization reactions [1,[6][7][8][9][10][11][12] as well as hydrosilylation have been published, although not as widely as the corresponding palladium NHC systems which have found very broad application as catalysts for such coupling reactions. [1,[13][14][15][16][17][18][19] Generation of ADC metal complexes may be accomplished by direct complexation of the free carbenes or by metalmediated nucleophilic addition to isonitriles.…”

“…Acyclic diamino carbenes (ADC) and their metal complexes have attracted great interest in recent years due to their similarities with N‐heterocyclic carbenes (NHC). Compared to NHCs which are widely used as components of catalysts, ADCs generally have a stronger σ donor character and a wider N−C−N angle, allowing for a closer approach of a coordinated metal center to provide better steric control [1,2] …”