Coinage Metal Complexes of Bis(quinoline‐2‐ylmethyl)phenylphosphine‐Simple Reactions Can Lead to Unprecedented Results

Abstract

The different coordination behavior of the flexible yet sterically demanding, hemilabile P,N ligand bis(quinoline-2-ylmethyl)phenylphosphine (bqmpp) towards selected Cu^I , Ag^I and Au^I species is described. The resulting X-ray crystal structures reveal interesting coordination geometries. With [Cu(MeCN)₄ ]BF₄ , compound 1 [Cu₂ (bqmpp)₂ ](BF₄ )₂ is obtained, wherein the copper(I) atoms display a distorted square planar and square pyramidal geometry. The steric demand and π-stacking of the ligand allow for a short Cu⋅⋅⋅Cu distance (2.588(9) Å). Cu^I complex 2 [Cu₄ Cl₃ (bqmpp)₂ ]BF₄ contains a rarely observed Cu₄ Cl₃ cluster, probably enabled by dichloromethane as the chloride source. In the cluster, even shorter Cu⋅⋅⋅Cu distances (2.447(1) Å) are present. The reaction of Ag[SbF₆ ] with the ligand leads to a dinuclear compound (3) in solution as confirmed by ³¹ P{¹ H} NMR spectroscopy. During crystallization, instead of the expected phosphine complex 3, a tris(quinoline-2-ylmethyl)bisphenyl-phosphine (tqmbp) compound [Ag₂ (tqmbp)₂ ](SbF₆ )₂ 4 is formed by elimination of quinaldine. The Au(I) compound [Au₂ (bqmpp)₂ ]PF₆ (5) is prepared as expected and shows a linear arrangement of two phosphine ligands around Au^I .