Synthesis and reactivity of bis(3,5-dimethylpyrazol-1-yl)ethane tetracarbonylmolybdenum and tungsten X-ray crystal structure of bis(3,5-dimethylpyrazol-1-yl)ethane tetracarbonyltungsten

Bis(3,5-dimethylpyrazol-1-yl)ethane tetracarbonylmolybdenum (1a) and tungst en (1b) have been synthesized by the direct reaction of bis(3,5-dimethylpyr azolyl)ethane (bmpze) with M(CO)(6) (M = Mo or W). The molecular structure (1b), determined by x-ray crystallography, showed the seven-membered ring W -N-N-C-C-N-N to be in the boat conformation. Upon treatment with RSnCl3 (R= Ph or Cl) in CH2Cl2 at room temperature, complexes (1a) and (1b) gave the s even-coordinate oxidative-addition products [(bmpze)M(CO)(3)(SnCl2R)Cl] [M = Mo, R = Ph, (2a); M = W, R=Ph, (2b); M = Mo, R = Cl, (2c); M = W, R = Cl, (2d)]. When complexes (1b) and (2b) were heated under reflux with 1,2-bis( diphenylphosphino)ethane (dppe), the ligand, bmpze, in these complexes was easily removed. The novel compounds were characterized by H-1-n.m.r., i.r. and elemental analysis.