Synthesis and Structures of [Mo 12 E 16 (PEt 3 ) 10 ] (E = S, Se)

Dodecanuclcar cluster complexes [Mo 12 S 16 (PEt 3 ) 10 ] 1 and [Mo 12 Se 16 (PEt 3 ) 10 ] 2 have been prepared by the reactions of [Mo 6 S 8 (PEt 3 ) 6 ] with sulfur or [Mo 6 Se 8 (PEt 3 ) 6 ] with Cp 2 TiSe 5 , respectively, in toluene at refluxing temperature. The structures have been determined at 173 K by X‐ray crystallography. The compound 1 ·3CHCl 3 crystallizes in the triclinic space group \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm P}\bar 1 $\end{document} , with a = 14.859(5) Å, b = 15.868(4) Å, c = 14.200(7) Å, α = 100.58(3)°, β = 117.58(3)°, γ = 79.53(2)°, V = 2899(1) Å 3 , and Z = 1. Full‐matrix least‐squares refinement using 9016 observed reflections ( I o > 2σ( I o )) gave R = 0.056, and R w = 0.045. The data for 2 ·2CHCl 3 are: triclinic, \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm P}\bar 1 $\end{document} , a = 15.737(4) Å, b = 18.763(9) Å, c = 13.062(4) Å, α = 102.45(3)°, β = 128.54(2)°, γ = 69.49(3)°, V = 2825 Å 3 , Z = 1, R = 0.096, and R w = 0.120 for 5922 reflections ( I o > 2σ( I o )). The cluster complexes 1 and 2 have two octahedral molybdenum cluster units linked by the rhomboidal intercluster Mo 2 (μ 4 ‐E) 2 bonding. The intercluster Mo—Mo distances in 1 are 3.419 Å and 2 3.551 Å. The cyclic voltammetry of 1 and 2 shows two oxidation and two reduction steps separated as large as 380–490 mV. The UV‐Vis spectra of the dodecanuclear cluster complexes 1 and 2 have an extra weak band at around 744 nm which is absent in the starting octahedral cluster complexes.