Complexes of tris(3,5-dimethylpyrazolyl)borates alkylated on the 4-position of the pyrazolyl rings. X-ray crystal structure of molybdenum dicarbonyl nitrosyl tris(3,5-dimethyl-4-n-butylpyrazolyl)borate

The 4-substituted tris(3,5-dimethylpyrazolyl)borato compounds [Mo(CO)(2)(NO){HB(4-R-dmpz)(3)}] (R: = Me, Et, Bu(n) and C5HII) and [MoCl2(NO){HB(4-R-dmpz)(3)}] (R = Me or Bu(n)) have been prepared and characterized spectroscopically and electrochemically. X-ray crystal structural determination of [Mo(CO)(2)(NO){HB(4-R-dmpz)(3)}] (R = Bu(n)) revealed that the n-butyl chains attached to the 4-position of the pyrazolyl rings were orientated, overall, in a random fashion, although the fist and second C atoms of each chain extended in a star-shaped configuration, similar to that observed in [Mo(CO)(2)(NO){HB(4-bzdmpz)(3)}](4-bzdmpz = 4-benzyl-3,5-dimethylpyrazolyl)