Solvent extraction syntheses and 1H NMR spectra of incomplete cubane-type sulfur/oxygen-bridged molybdenum clusters with 8-quinolinolato ligands - Anomalous chemical shifts

Solvent extraction technique gave six incomplete cubane-type sulfur/oxygen-bridged molybdenum clusters with 8-quinolinol or 5-chloro-8-quinolinol ligands, [Mo3S4(C9H5ClNO)3(H2O)3]+, [Mo3S4(C9H6NO)3(H2O)3]+, [Mo3OS3(C9H6NO)3(H2O)3]+, [Mo3O2S2(C9H6NO)3(H2O)3]+, [Mo3O3S(C9H6NO)3(H2O)3]+, and [Mo3O4(C9H6NO)3(H2O)3]+ from corresponding aqua clusters, [Mo3O4−nSn(H2O)9]4+ (n = 0-4). Hydrogen bonding of C-H⋯(μ-S) caused large downfield chemical shifts in the 1H NMR spectra of the sulfur-bridged clusters.