Allyl molybdenum(II) and tungsten(II) compounds bearing bidentate and tridentate pyrazolylmethane ligands

This study describes reaction of allyl molybdenum and tungsten complexes [(η3-C3H5)M(CO)2(NCMe)2Cl] (M = Mo, W) with tris(pyrazolyl)methane (tpm). This tridentate scorpionate ligand produces two types of products. The neutral κ2-complexes [(η3-C3H5)M(CO)2(κ2-tpm)Cl] (M = Mo, W) were isolated from non-aqueous media while an aqueous work up gives the cationic κ3-complexes [(η3-C3H5)M(CO)2(κ3-tpm)]+ (M = Mo, W). The coordination mode of the tridentate ligand was resolved by 1H NMR spectroscopy. This study further covers the model systems with the bidentate ligands bis(pyrazolyl)methane (bpm) and bis(1,3-dimethylpyrazolyl)methane (Me4bpm). All compounds under the study were characterized by the infrared spectroscopy. The structures of two molybdenum compounds [(η3-C3H5)Mo(CO)2(κ2-bpm)Cl], [(η3-C3H5)Mo(CO)2(κ3-tpm)][PF6]·CH2Cl2 and two tungsten compounds [(η3-C3H5)W(CO)2(κ2-Me4bpm)Cl], [(η3-C3H5)W(CO)2(κ3-tpm)][PF6]·CH2Cl2 were determined by the X-ray diffraction analysis.

Graphical abstractThe series of molybdenum and tungsten complexes bearing bidentate and tridentate pyrazolylmethane ligands was synthesized and characterized by the spectroscopic methods. Two structure types were determined by the X-ray diffraction analysis.Figure optionsDownload full-size imageDownload as PowerPoint slide