Structure and coordination chemistry of sterically demanding phenylcycloarsoxane

Tetrameric phenylcycloarsoxane (C6H5AsO)(4) 1 exhibits a boat-chair-conformation in the solid state. Its reaction with CuI in benzonitrile leads to the formation of coordination polymers. infinity(1)[(CuI . C6H5CN){cyclo-(C6H5AsO)(4)}] (2) underlines the structure-directing steric requirements of the phenyl side chains. Treatment of 1 with M(CO)(6) (M = Cr, Mo) confirms its capability to undergo metal-mediated ring expansion. In [{M(CO)(3)}(2){cyclo-(C6H5AsO)(6)}] with M = Cr (3) and M = Mo (4), twelve membered As-O-rings are stabilised by the participation of alternating As atoms in the coordination spheres of opposite facial transition metal carbonyl fragments M(CO)(3).