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Abstract
The syntheses and molecular structures of carbene-stabilized arsenic derivatives of AsCl3 (L1:AsCl3 (1); L1: = :C{N(2,6-iPr2C6H3)CH}2), and As2 (L1:AsAs:L1 (2)), are presented herein. The potassium graphite reduction of 1 afforded the carbene-stabilized diarsenic complex, 2. Notably, compound 2 is the first Lewis base stabilized diatomic molecule of the Group 1315 elements, in the formal oxidation state of zero, in the fourth period or lower of the Periodic Table. Compound 2 contains one AsAs -bond and two lone pairs of electrons on each arsenic atom. In an effort to study the chemistry of the electron-rich compound 2, it was combined with an electron-deficient Lewis acid, GaCl3. The addition of two equivalents of GaCl3 to 2 resulted in one-electron oxidation of 2 to give [L1:As As:L1]+[GaCl4] (6+[GaCl4]). Conversely, the addition of four equivalents of GaCl3 to 2 resulted in two- electron oxidation of 2 to give [L1:As=As:L1]2+[GaCl4]2 (62+[GaCl4]2). Strikingly, 6+ represents the first arsenic radical to be structurally characterized in the solid state. The research project also explored the reactivity of carbene-stabilized disilicon, (L1:Si=Si:L1 (7)), with borane. The reaction of 7 with BH3THF afforded two unique compounds: one containing a parent silylene (:SiH2) unit (8), and another containing a three-membered silylene ring (9). Notably, 8 is the first example of a pushpull stabilized parent silylene, while 9 is the first example of a three-membered cyclic silylene, both of which are persistent under ambient conditions.