Binding, Release and Functionalization of Intact Pnictogen Tetrahedra Coordinated to Dicopper Complexes

Abstract The bridging MeCN ligand in the dicopper(I) complexes [(DPFN)Cu 2 (μ,η 1 : η 1 ‐MeCN)][X] 2 (X=weakly coordinating anion, NTf 2 ( 1 a ), FAl[OC 6 F 10 (C 6 F 5 )] 3 ( 1 b ), Al[OC(CF 3 ) 3 ] 4 ( 1 c )) was replaced by white phosphorus (P 4 ) or yellow arsenic (As 4 ) to yield [(DPFN)Cu 2 (μ,η 2 : η 2 ‐E 4 )][X] 2 (E=P ( 2 a – c ), As ( 3 a – c )). The molecular structures in the solid state reveal novel coordination modes for E 4 tetrahedra bonded to coinage metal ions. Experimental data and quantum chemical computations provide information concerning perturbations to the bonding in coordinated E 4 tetrahedra. Reactions with N‐heterocyclic carbenes (NHCs) led to replacement of the E 4 tetrahedra with release of P 4 or As 4 and formation of [(DPFN)Cu 2 (μ,η 1 : η 1 ‐ Me NHC)][X] 2 ( 4 a,b ) or to an opening of one E−E bond leading to an unusual E 4 butterfly structural motif in [(DPFN)Cu 2 (μ,η 1 : η 1 ‐E 4 Dipp NHC)][X] 2 (E=P ( 5 a,b ), E=As ( 6 )). With a cyclic alkyl amino carbene ( Et CAAC), cleavage of two As−As bonds was observed to give two isomers of [(DPFN)Cu 2 (μ,η 2 : η 2 ‐As 4 Et CAAC)][X] 2 ( 7 a,b ) with an unusual As 4 ‐triangle+1 unit.