Investigations of the Coordination Chemistry of Molybdenum with Facultative Tetradentate Ligands Possessing N₂S₂ Donor Sets. 5. Crystal and Molecular Structures of the Hydrazido(2−) and Diazenido Derivatives [MoO(N₂Ph₂)L] and [Mo(N₂C₆H₄OCH₃)₂L]

The crystal and molecular structures of two derivatives of Mo(VI) with substituted hydrazine ligands, oxo[diphenylhydrazido(2-)] [N,N′-dimethyl-N,N′-bis(mercaptoethyl)ethylenediamine]molybdenum(VI), [MoO(N₂Ph₂)L], and [bis((p-methoxyphenyl)diazenido)][N,N′-dimethyl-N,N′-bis(mercaptoethyl)ethylenediamine]molybdenum(VI), [Mo(N₂C₆H₄OCH₃)₂L], are reported. [MoO(N₂Ph₂)L] crystallizes as red needles in space group P2₁/c with unit cell dimensions a = 13.248 (2) Å, b = 11.229 (2) Å, and c = 15.780 (2) Å and with β = 109.46 (1)° and Z = 4. The structure has been refined to R₁ = 0.027 and R₂ = 0.048 on the basis of 2784 independent reflections. The molecule is pseudooctahedral with the hydrazido(2-) group eis to the oxo ligand. [Mo(N₂C₆H₄OCH₃)₂L] crystallizes in space group Cc with unit cell dimensions a = 22.557 (2) Å, b = 8.483 (3) Å, and c = 18.030 (2) Å and with β = 133.25 (1)° and Z = 4. The structure refined to values of R₁ and R₂ of 0.043 and 0.049, respectively, on the basis of 1505 independent reflections. The diazenido ligands are mutually cis and enjoy significant multiple-bond interaction with the molybdenum, as indicated by the short average Mo-N distance of 1.81 (2) Å. In both structures, the ligand L exhibits the sterically strained configuration associated with this tetradentate ligand. The electrochemistry of a series of complexes of the type [Mo(N₂C₆H₄X)₂L] is discussed and related to the geometry of the diazenido ligands.