Preparation of methylhydrazine and methyldiazene complexes of molybdenum and tungsten

Nitrosyl complexes [M(CO)3(NO)L2]BPh4 (2, 5) [M = Mo, W; L = PPh(OEt)2, PPh2OEt] were prepared by allowing carbonyl compounds M(CO)4L2 (1, 4) to react with NOPF6 in CH2Cl2. Dicarbonyl complex [W(CO)2(NO){PPh(OEt)2}3]BPh4 (7) was also prepared by reacting W(CO)3[PPh(OEt)2]3 (6) with NOPF6. Treatment of nitrosyl complexes 2, 5 with [NEt4]Br gave bromide derivative [MBr(CO)2(NO)L2]BPh4 (3). Hydrazine complexes [M(CO)(RNHNH2)(NO)L3]BPh4 (8, 9, 10) (R = H, CH3) were prepared by allowing nitrosyl complexes 2, 5 to react with hydrazine RNHNH2 in CH2Cl2. Reaction of methylhydrazine complexes [M(CO)(CH3NHNH2)(NO)L3]BPh4 (8, 10) with Pb(OAc)4 at −30 °C resulted in selective oxidation of hydrazine, affording the corresponding methyldiazene derivatives [M(CO)(CH3NNH)(NO)L3]BPh4 (11, 12). The complexes were characterised spectroscopically (IR and NMR), and a geometry in solution was also established.

Graphical abstractThe preparation of mixed-ligands complexes of molybdenum and tungsten with carbonyl, nitrosyl and phosphonite or phosphinite ligands is described. The reaction with CH3NHNH2 leading to methylhydrazine complexes [M(CO)(CH3NHNH2)(NO)L3]BPh4 is also reported. The selective oxidation of coordinate methylhydrazine to methyldiazene is discussed.Figure optionsDownload full-size imageDownload as PowerPoint slide