Heterotrimetallic compounds containing Mo-M-Li [M = K, Rb and Cs] clusters: Synthesis, structure, bonding, aromaticity and theoretical investigations of Li <inf>2</inf>M <inf>2</inf> [M = K and Rb] and Cs <inf>4</inf> rings

Abstract

A new polydentate fac-trioxo molybdenum complex, [MoO 3L] 3- {LH 3 = nitrilotriacetic acid}, has been synthesized by the reaction of lithium molybdate with iminodiacetic acid. The trinegative complex anion coordinates the alkali metal cations, K +, Rb + or Cs +. The potassium, rubidium and cesium complexes, [Li{K(H 2O) 2}MoO 3L] n (1), [Li{Rb(H 2O) 2}MoO 3L] n (2) and [Cs{Li(H 2O)} 2MoO 3L] n (3), form heterotrimetallic coordination chains, containing planar rings of Li 2M 2 (M = K or Rb) and Cs 4. Theoretical investigations on these rings were carried out using NICS calculations and ab initio ring current maps, revealing aromaticity to be of limited significance. © 2012 the Owner Societies.