The bridging MeCN ligand in the dicopper(I) complexes [(DPFN)Cu-2(mu,eta(1) : eta(1)-MeCN)][X](2) (X=weakly coordinating anion, NTf2 (1 a), FAl[OC6F10(C6F5)](3) (1 b), Al[OC(CF3)(3)](4) (1 c)) was replaced by white phosphorus (P-4) or yellow arsenic (As-4) to yield [(DPFN)Cu-2(mu,eta(2) : eta(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(mu,eta(1) : eta(1)-(NHC)-N-Me)][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(mu,eta(1) : eta(1)-(E4NHC)-N-Dipp)][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(mu,eta(2) : eta(2)-As(4)(Et)CAAC)][X](2) (7 a,b) with an unusual As-4-triangle+1 unit.