Synthesis and crystal structure of the cluster (Et₄N)[(Tp*)MoFe₃S₃(μ₃-NSiMe₃)(N₃)₃]

The title compound, tetra-ethyl-ammonium tri-azido-tri-μ₃-sulfido-[μ₃-(tri-methyl-sil-yl)aza-nediido][tris-(3,5-di-methyl-pyrazol-1-yl)hydro-borato]triiron(+2.33)molybdenum(IV), (C₈H₂₀N)[Fe₃MoS₃(C₁₅H₂₂BN₆)(C₃H₉NSi)(N₃)₃] or (Et₄N)[(Tp*)MoFe₃S₃(μ₃-NSiMe₃)(N₃)₃] [Tp* = tris-(3,5-di-methyl-pyrazol-1-yl)hydro-bor-ate(1-)], crystallizes as needle-like black crystals in space group P . In this cluster, the Mo site is in a distorted octa-hedral coordination model, coordinating three N atoms on the Tp* ligand and three μ₃-bridging S atoms in the core. The Fe sites are in a distorted tetra-hedral coordination model, coordinating two μ₃-bridging S atoms, one μ₃-bridging N atom from Me₃SiN^2-, and another N atom on the terminal azide ligand. This type of heterometallic and heteroleptic single cubane cluster represents a typical example within the Mo-Fe-S cluster family, which may be a good reference for understanding the structure and function of the nitro-genase FeMo cofactor. The residual electron density of disordered solvent mol-ecules in the void space could not be reasonably modeled, thus the SQUEEZE [Spek (2015). Acta Cryst. C71, 9-18] function was applied. The solvent contribution is not included in the reported mol-ecular weight and density.