Photochemical reactions of metal carbonyls with heteroaromatic methanesulfonylhydrazone-based ligands

Three new heteroaromatic methanesulfonylhydrazone derivatives: thiophene-2-carboxy aldehydemethanesulfonylhydrazone (msh 1), 2-acetylthiophenemethanesulfonylhdrazone (msh 2), and 2-acetyl-5-methylthiophenemethanesulfonylhydrazone (msh 3) were prepared and their metal carbonyl complexes ([M(CO)₅(msh 1)] M = Cr, 1a; Mo, 1b; W, 1c); ([M(CO)₅(msh 2)] M = Cr, 2a; Mo, 2b; W, 2c); and ([M(CO)₅(msh 3)] M = Cr, 3a; Mo, 3b; W, 3c) were synthesized by photochemical reactions of [M(CO)₆ M = Cr, Mo, W] with msh 1-3. Heteroaromatic methanesulfonylhydrazones, msh 1-3, and their metal carbonyl complexes were characterized by elemental analysis, mass spectrometry, IR, and ¹H and ¹³C-{¹H} NMR spectroscopy. According to all the spectroscopic data, msh 1-3 are monodentate and coordinate via thiophene ring sulfur. The msh 1-3 must act as two-electron donors to satisfy the 18-electron rule.