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

The title compound, tetraethylammonium triazidotri-μ 3 -sulfido-[μ 3 -(trimethylsilyl)azanediido][tris(3,5-dimethylpyrazol-1-yl)hydroborato]triiron(+2.33)molybdenum(IV), (C 8 H 20 N)[Fe 3 MoS 3 (C 15 H 22 BN 6 )(C 3 H 9 NSi)(N 3 ) 3 ] or (Et 4 N)[(Tp*)MoFe 3 S 3 (μ 3 -NSiMe 3 )(N 3 ) 3 ] [Tp* = tris(3,5-dimethylpyrazol-1-yl)hydroborate(1−)], crystallizes as needle-like black crystals in space group P 1̄. In this cluster, the Mo site is in a distorted octahedral coordination model, coordinating three N atoms on the Tp* ligand and three μ 3 -bridging S atoms in the core. The Fe sites are in a distorted tetrahedral coordination model, coordinating two μ 3 -bridging S atoms, one μ 3 -bridging N atom from Me 3 SiN 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 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 . C 71 , 9–18] function was applied. The solvent contribution is not included in the reported molecular weight and density.