A new synthetic route to Lindqvist type clusters [(n-Bu4N)x][M'M5O19] [when x = 2, M' = M = Mo or W; x = 3, M' = Mo, M = W] from metal carbonyl precursors [(CO)5ML] [M = Mo, W; L= CO, C(OMe)(Me)].

Two fully oxidized [(n-Bu4N)2][Mo6O19], 7 and [(n-Bu4N)2][W6O19], 8 and one mixed-metal, mixed-valence one electron reduced [(n-Bu4N)3][MoW5O19], 9 cluster have been synthesized under biphasic reaction conditions from group VI metal carbonyls or Fischer carbene complexes, [(CO)5M=C(OMe)Me] (M = Mo, W) in yields of 73, 77 and 71% respectively. All the clusters have been characterized by IR, 1H and 13C NMR spectra, and crystal structure determinations. Additionally, the composition of 9 has also been supported by mass spectrometry (MALDI-TOF), inductively coupled plasma (ICP) and energy-dispersive X-ray (EDX) analysis. This novel and mild route offers distinct improvements over earlier methods of synthesis for Lindqvist type mixed-valence mixed-metal polyoxometalate cluster.