Comparative structural studies on silver(i) complexes with tripodal polyphosphines. Crystallographic characterisation of the first infinite chain structures in 2 ∶ 1 adducts of silver(i) halides with 1,1,1-tris(diphenylphosphinomethyl)ethane

Abstract

The AgX salts [X = Cl, Br, I, NO₃] react with CP₃ [MeC(CH₂PPh₂)₃], PP₃ [P(CH₂CH₂PPh₂)₃] and NP₃ [N(CH₂CH₂PPh₂)₃] in 1 ∶ 1 stoichiometric ratio to afford complexes Ag(CP₃)X [X = Cl (1), Br (2), I (3)], Ag(PP₃)Cl (4), Ag(NP₃)Cl (6) and Ag(NP₃)(NO₃) (7) where Ag(I) is bound to three P atoms of the ligand. The X-ray crystal structure of complex 6 consists of a mononuclear compound with absence of the N atom of NP₃ in the coordination to the metal. The 1 ∶ 1 complex obtained by reaction of AgNO₃ with PP₃ was shown by conductivity measurements, mass spectrometry, infrared and NMR spectroscopy to be a dinuclear ionic complex [Ag₂(PP₃)₂](NO₃)₂ (5) where Ag(I) shows three- and four-coordination. The interaction of AgX halides with CP₃ in 2 ∶ 1 stoichiometric ratio leads to complexes Ag₂(CP₃)X₂ [X = Cl (8), Br (9), I (10)] which were shown by X-ray crystallography to consist of infinite zigzag (X = Cl, I) or linear (X = Br) chains containing three- and four-coordinate Ag(I) and constituting the first examples of such complexes with CP₃. These polymeric chains did not give reaction with another equivalent of AgX to form the Ag₃(CP₃)X₃ [X = Cl, Br, I] complexes. The 2 ∶ 1 and 3 ∶ 1 nitrate derivatives Ag₂(PP₃)(NO₃)₂ (11), Ag₂(NP₃)(NO₃)₂ (12), Ag₃(PP₃)(NO₃)₃ (13) and Ag₃(NP₃)(NO₃)₃ (14) show participation of the nitrate anion as ligand finding for 13 two different geometries about Ag(I) in solution. Complexes 13 and 14 react with the corresponding phosphines PP₃ and NP₃ to form complexes 5 and 7, respectively involving ring-closure reactions.