Carbene‐Stabilized Disilicon as a Silicon‐Transfer Agent: Synthesis of a Dianionic Silicon Tris(dithiolene) Complex

Abstract

Reaction of carbene‐stabilized disilicon (1) with the lithium‐based dithiolene radical (2.) affords the first dianionic silicon tris(dithiolene) complex (3). Notably, the formation of 3 represents the unprecedented utilization of carbene‐stabilized disilicon (1) as a silicon‐transfer agent. The nature of 3 was probed by multinuclear NMR spectroscopy, single‐crystal X‐ray diffraction, and DFT computations.

Saturated NHC Derived Dichalcogen Dications

“…Among main-group compounds, the use of NHCs in the isolation of compounds III-E featuring a diatomic E 2 moiety [8] is remarkable as they may formally be considered as organic solvent soluble allotropes of main-group elements. [9] Indeed, they exhibit interesting electronic structures and reactivity, including transfer of E 2 (or E) moiety on to a different substrate from III-E. [10] Cyclic alkyl amino carbenes (cAACs) have also been found to be useful in accessing similar compounds. [11] tives (SIPr)E (2a-E), which readily undergo oxidative E-E coupling reactions with triflic anhydride to yield the corresponding products 3a-E.…”

Carbene‐Stabilized Dithiolene (L0) Zwitterions

“…Unexpectedly, the parallel reaction of 1 with sterically demanding NHSi Dipp[18] (Dipp=2,6‐diisopropylphenyl) ( 6 ) quantitatively resulted in colourless spirocyclic silicon–dithiolene complex ( 7 ) (Scheme 2). [8] Consequently, 7 joins a small group of structurally characterized silicon–dithiolene complexes [5c, 19] . To the best of our knowledge, the literature does not reveal a report of stable carbene‐, or silylene‐, mediated cleavage of a sulphur–sulphur bond (in a molecular compound).…”

“…X‐ray structural analysis [8] (Figure 5 b) shows that the four‐coordinate silicon atom in 7 adopts a distorted tetrahedral geometry ( τ =0.78) [22] . Similar to that [2.1381(6) Å] of Si[S 2 ( o ‐C 6 H 4 )] 2 containing a four‐coordinate silicon atom, [19a] the Si−S bond distances of 7 [2.1604(4) Å, av] are much shorter than those [2.3195(12)‐2.3374(12) Å] in the reported silicon tris(dithiolene) dianion containing a six‐coordinate silicon atom [5c] . The bonding parameters of the C 2 S 2 unit [d C‐ S =1.7357(9) Å, av; d C=C =1.3468(12) Å] of 7 are consistent with those for the reported dithiolates [2a, 23] .…”

Carbene‐Stabilized Disilicon as a Silicon‐Transfer Agent: Synthesis of a Dianionic Silicon Tris(dithiolene) Complex

“…While being similar to those in [Si(Tm Ph ) 2 ] 2+ dications (2.3176 , av), [22] the SiÀS bonds of 3 [2.3195(12)-2.3374 (12) ] are somewhat ; thermal ellipsoids set at 30 % probability; hydrogen atoms bound to carbon atoms are omitted for clarity). [25] 1 a). [6a] The zwitterionic pentacoordinate silicon bis(dithiolene) (Figure 1 b) contains both [2.1590(9) , av] equatorial and [2.3076 (7) , av] axial SiÀS bonds.…”

“…Figure 2. a) Molecular structure of silicon tris(dithiolene) dianion ([3] 2À; thermal ellipsoids set at 30 % probability; hydrogen atoms bound to carbon atoms are omitted for clarity) [25]. Selected bond lengths [] and angles (8): C(1)-S(1) 1.680(4), C(2)-C(3) 1.342(4), C(2)-S(2) 1.729(3), C(3)-S(3) 1.725(3), S(2)-Si(1) 2.3195(12), S(3)-Si(1) 2.3374(12); S(2)-C(2)-C(3) 124.9(3), C(2)-S(2)-Si(1) 95.10(11), S(2)-Si(1)-S(3) 94.71(3), S(2)-Si(1)-S(3A) 177.19(3).…”