Difluorobis(pentafluoroethyl)phosphoranide: A Promising Building Block for Phosphoranidometal Complexes.

Despite the fact that different metal tetrafluorophosphoranides, M[PF4] (M = Cs, Ag, K), decompose readily, we successfully enhanced the stability of such species by the replacement of two fluorine atoms with electron withdrawing pentafluoroethyl groups. Thus, AgF adds to P(C2F5)2F, yielding Ag[P(C2F5)2F2], which served as a starting material for the synthesis of mono-, bis-, and tris[difluorobis(pentafluoroethyl)phosphoranido]silver complexes. Addition of 2,2'-bipyridine allowed for the isolation of stable [Ag(bipy){P(C2F5)2F2}], whereas the reaction with the chlorides [NMe4]Cl and CoCl2 afforded the bis- and trisphosphoranidoargentates [NMe4][Ag{P(C2F5)2F2}2(OEt2)] and [Co(NCMe)6][Ag{P(C2F5)2F2}3]·2MeCN, respectively. Altogether, the difluorobis(pentafluoroethyl)phosphoranido moiety serves as a novel, small, noncyclic phosphoranido ligand. It provided access to the first homoleptic phosphoranidometal complex, [Co(NCMe)6][Ag{P(C2F5)2F2}3]·2MeCN, which itself features the unusual structural motif of an [AgX3]2- ion.