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Abstract：
One-electron oxidation of the disilicon(0) compound Si2(Idipp)2 (1, Idipp = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) with [Fe(C5Me5)2][B(Ar(F))4] (Ar(F) = C6H3-3,5-(CF3)2) affords selectively the green radical salt [Si2(Idipp)2][B(Ar(F))4] (1-[B(Ar(F))4). Oxidation of the centrosymmetric 1 occurs reversibly at a low redox potential (E1/2 = -1.250 V vs. Fc(+)/Fc), and is accompanied by considerable structural changes as shown by single-crystal X-ray structural analysis of 1-B(Ar(F))4. These include a shortening of the Si-Si bond, a widening of the Si-Si-CNHC angles, and a lowering of the symmetry, leading to a quite different conformation of the NHC substituents at the two inequivalent Si sites in 1(+). Comparative quantum chemical calculations of 1 and 1(+) indicate that electron ejection occurs from the symmetric (n+) combination of the Si lone pairs (HOMO). EPR studies of 1-B(Ar(F))4 in frozen solution verified the inequivalency of the two Si sites observed in the solid-state, and point in agreement with the theoretical results to an almost equal distribution of the spin density over the two Si atoms, leading to quite similar (29)Si hyperfine coupling tensors in 1(+). EPR studies of 1-B(Ar(F))4 in liquid solution unraveled a topomerization with a low activation barrier that interconverts the two Si sites in 1(+).
摘要：
二硅(0)化合物Si2(Idipp)2(1,Idipp=1,3-双(2,6-二异丙基苯基)咪唑啉-2-亚基)与[Fe(C5Me5)2][B(Ar(F))4](Ar(F)=C6H3-3,5-(CF3)2)的单电子氧化选择性地提供绿色盐[Si2(Idipp)中心对称1的氧化在低氧化还原电位（E1/2=-1.250Vvs.Fc（+）/Fc），并伴随着相当大的结构变化，如1-B（Ar（F））4的单晶X射线结构分析所示。这些包括Si-Si键的缩短，Si-Si-CNHC角度的加宽，对称性的降低，导致1（）中两个不等效Si位点的NHC取代基构象完全不同。1和1（）的比较量子化学计算表明，电子喷射是由Si孤对（HOMO）的对称（n）组合产生的。冷冻溶液中1-B（Ar（F））4的EPR研究证实了在固态下观察到的两个Si位点的不等效性，与理论结果一致，自旋密度在两个Si原子上的分布几乎相等，导致1(+)中非常相似的(29)Si超精细耦合张量。在液体溶液中对1-B（Ar（F））4进行的EPR研究揭示了具有低活化势垒的局部聚合反应，该活化势垒使1（）中的两个Si位点相互转化。
