Supramolecular Assemblies of Polyphosphorus Ligands Based on Weak Tl–P and In–P Interactions

Abstract

Abstract A systematic investigation of the coordination behavior of Pn complexes towards the main group Lewis acids Tl+ and In+ is presented. While the reaction of the tetrahedral P2 complex [{CpMo(CO)2}2(μ,η2:η2-P2)] (A1) with Tl[TEF] ([TEF] = [Al{OC(CF3)3}4]-) leads to the formation of the dicationic complex [Tl2(A1)6]2+ (1) with a central six-membered Tl2P4 ring, the analogous reaction with In[TEF] leads instead to a tetranuclear [In4(A1)8]4+ complex (3) exhibiting a weak InI-InI interaction in the solid state. When the Cp*-analogous P2 complex [{Cp*Mo(CO)2}2(μ,η2:η2-P2)] (A2) is reacted with Tl[TEF] the dinuclear complex [Tl2(A2)4]2+ (2) is formed, containing only four P2 ligands but also featuring a six-membered Tl2P4 ring motif. From the reactions of the cyclo-P3 complexes [CpM'(CO)2(η3-P3)] (M' = Cr (B1), Mo (B2)) with In[TEF] and Tl[TEF], a series of four isostructural one-dimensional coordination polymers (4a-d) are obtained which exhibit a novel bridging coordination mode of the cyclo-P3 ligands in the solid state. Additionally, the mixed PmSn ligand complex [(Cp*Mo)2(μ,η3:η3-P3)(μ,η2:η2-PS)] (C) was reacted with Tl[TEF] to afford a novel one-dimensional coordination polymer (5), which shows an unprecedented bridging s-1,3-coordination mode of ligand C towards Tl+. The compounds were analyzed by single-crystal X-ray structure determination, elemental analysis, and mass spectrometry, as well as by multinuclear NMR and IR spectroscopy. All products are readily soluble in CH2Cl2, despite in many cases being polymeric in the solid state. Multinuclear NMR spectroscopy suggests a highly dynamic coordination behavior in solution, including fast equilibria between different monomeric species, which is also supported by DFT calculations. The one-dimensional polymers 4c and 4d reveal a triplet in the 31P{1H} MAS NMR spectrum at room temperature, which could be explained by fast rotation of the P3 rings in the solid state.