Taming of Low-Valent Arsenic Compounds and Transfer of Nascent As2 Facilitated by a Frustrated Lewis Pair.

The first examples of frustrated Lewis pair (FLP)-stabilized compounds with formal oxidation states of arsenic ranging from -1 to +1 have been synthesized. These chelates include the metalated arsinidenyl As(─I) anion in FLP{As─K} (1), which provides access to the parent FLP-stabilized arsinidene, As(+I)─H, in FLP{As─H} (3), and a diatomic arsenic(0) allotrope within FLP{As─As}FLP (5). Irradiation of the As2 complex 5 represents an unprecedented method for the generation of nascent diarsenic, As2 nasc, which shows triple-bond like reactivity with a diene and selective As2 unit insertion into metal-metal bonds under mild conditions.