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

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 nitro­genase FeMo cofactor.

The title compound, tetra­ethyl­ammonium tri­azido­tri-μ₃-sulfido-[μ₃-(tri­methyl­sil­yl)aza­nediido][tris­(3,5-di­methyl­pyrazol-1-yl)hydro­borato]triiron(+2.33)molybdenum(IV), (C₈H₂₀N)[Fe₃MoS₃(C₁₅H₂₂BN₆)(C₃H₉NSi)(N₃)₃] or (Et₄N)[(Tp*)MoFe₃S₃(μ₃-NSiMe₃)(N₃)₃] [Tp* = tris­(3,5-di­methyl­pyrazol-1-yl)hydro­bor­ate(1−)], crystallizes as needle-like black crystals in space group P

. In this cluster, the Mo site is in a distorted octa­hedral 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 tetra­hedral coordination model, coordinating two μ₃-bridging S atoms, one μ₃-bridging N atom from Me₃SiN²⁻, 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 nitro­genase FeMo cofactor. The residual electron density of disordered solvent mol­ecules 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 mol­ecular weight and density.