Alkali Metal/Lanthanoid Heterobimetallic Complexes of 8‐Hydroxyquinolines Accessed by Pseudo‐Solid‐State Reactions

Abstract

AbstractThe heterobimetallic 1D‐polymeric alkali metal/lanthanoid [AMLn(Q)4]n [Q = OQ (8‐quinolinolate): AM = Li, Ln = Tb, Ho, Er; AM = K, Ln = Er; Q = MQ (2‐methyl‐8‐quinolinolate): AM = Rb; Ln = Tb, Er] complexes were obtained after rearrangement reactions between AM(Q) and Ln(Q)3 in a 1,2,4,5‐tetramethylbenzene flux at elevated temperatures. In these compounds, the eight‐coordinate lanthanoid ion is surrounded by four (O, N) chelating Q ligands, which bridge to the adjacent alkali metal through their oxygen atoms to form the linear polymers. Dimeric [Cs2(MQ)2(HMQ)2] was obtained from an attempt to prepare [CsEr(MQ)4]n, and the caesium atoms are each ligated by one terminal HMQ and one chelating‐bridging MQ ligand. In addition, the chelating‐bridging ligands in [Cs2(MQ)2(HMQ)2] and in the rubidium derivatives [RbLn(MQ)4]n (Ln = Tb, Er) exhibit bonding of the π‐electron system to coordination saturate the large ionic alkali metal ion. The reaction of Yb(MQ)3 in the presence of K2C2O4·H2O afforded the monomeric heterobimetallic [KYb2(MQ)7] complex in which the three metal atoms are arranged in a triangular fashion. They are surrounded by seven MQ ligands, which display the previously encountered chelating (O, N) and the chelating‐bridging μ‐κ2(N,O):κ1(O) and μ3‐κ2(N,O):κ1(O):κ1(O) ligation modes. Heating K(OQ) in 1,2,3,4‐tetrachlorobenzene gave crystals of 8‐hydroxyquinolinium chloride. The structure of [Na4(OQ)4(H2O)8]n, obtained by neutralisation, has sodium ions coordinated by one chelating OQ and four aqua ligands, the latter bridge to adjacent sodium ions to give a double stranded 2D‐polymer.