Preparation and reactions of nitrosyl complexes of molybdenum and tungsten; X-ray structure of trans-[Mo(OH)(NO)(Ph2PCH2CH2PPh2)2]·2C4H8O
Abstract
The nitrosyl complexes trans-[MX(NO)(dppe)2](1; X = NCO, H, or OH; dppe = Ph2PCH2CH2PPh2; M = Mo or W) have been prepared by treating trans-[M(N2)2(dppe)2] with MeN(NO)C(O)NH2 in tetrahydrofuran (thf)(X = NCO), Et2NNO in thf or thf–MeOH (X = H), or Et2NNO in thf–K2[CO3](X = OH). The crystal structure of trans-[Mo(OH)(NO)(dppe)2]·2thf shows the trans geometry and a linear MO–N–O system apparently with a rather long MO–N distance [1.985(7)Å] and rather short Mo–OH distance [1.922(8)Å]. A series of analogues (1; X = N3, Cl, Br, I, or NCS) has been prepared by metathesis. Chemical oxidation of these compounds gives the complexes [MI(NO)(dppe)2][I3](from I2), [MX(NO)(dppe)2]Y (Y = FeCl4, CuCl2, or BF4), [Mo(NO)(NCR)(dppe)2][BF4], and [Mo(NO)(NCR)(dppe)2][BF4]2(Ag[BF4] in RCN, R = Me or Ph). Halogen (Cl2 or Br2) oxidation of (1; X = Cl or Br) gives the compounds [MCl2(dppe)2] and [MBr2(dppe)2]Br. These reactions and other physical properties of the complexes are discussed in terms of their structural and electrochemical data and possible mechanisms for the formation of (1; X = OH or H) are considered.