Synthesis and structural characterisation of glucofuranoside and galactopyranoside derivatives of [tris(3,5-dimethylpyrazolyl)borato]-molybdenum and -tungsten nitrosyls

Abstract

The complex [M(NO)L*X₂][L*= tris(3,5-dimethylpyrazolyl)borate; M = Mo, X = Cl or l; M = W, X = Cl] reacted with 1,2:5,6-di-O-isopropylidene-D-glucofuranose (HG_f) and with 1,2:3,4-di-O-isopropylidene-D-galactopyranose (HG_p) to give diastereomers of [M(NO)L*(X)G_f] and [M(NO)L*(X)G_p]. The structure of the thermodynamically stable diasteromer of [Mo(NO)L*(I)G_f] was determined by a single-crystal X-ray diffraction study, which showed the absolute configuration at the Mo atom to be S, in agreement with the known configuration of the mentholate R-[Mo(NO)L*(Cl){(–)-OC₁₀H₁₉}] and the circular dichroism (CD) spectra. The absolute configurations of the other isolated diastereomers were related to this complex and to R-[Mo(NO)L*Cl{(–)-OC₁₀H₁₉}] by comparison of their CD spectra.