Reactivity of Yellow Arsenic towards Cyclic (Alkyl)(Amino) Carbenes (CAACs).

Different cyclic (alkyl)(amino)carbenes (CAACs) were reacted with yellow arsenic. Several products [(CAAC-n)2 (μ,η1:1 -As2 )] (n=1 (1), 4 (2)), [(CAAC-2)3 (μ3 ,η1:1:1 -As4 )] (3) and [(CAAC-3)4 (μ4 ,η1:1:1:1 - As8 )] (6) were isolated due to the differing steric properties of CAAC-1-4. The products contain As2 , As4 or As8 units and represent the first examples of CAACs-substituted products of yellow arsenic. The reactivity of As4 was compared with the reactivities of P4 and the interpnictogen compound AsP3 , which led to a series of phosphorus-containing derivatives such as ([(CAAC-3)3 (μ3 ,η1:1:1 -P4 )] (4) and [(CAAC-3)4 (μ4 ,η1:1:1:1 -P8 )] (7)) and [(CAAC-3)3 (μ3 ,η1:1:1 -AsP3 )] (5). The products were characterized by spectroscopic and crystallographic methods and DFT computations were performed to clarify their formation pathway.