Novel [{Cp(CO) 2 Mo} 2 E Sb] + Clusters with Tetrahedral Mo 2 Sb E Core. Synthesis and Crystal Structures of [{Cp(CO) 2 Mo} 2 E Sb][GaCl 4 ] ( E = S, Se)

Treatment of the cluster compounds [Cp 2 (CO) 4 Mo 2 E SbCl] ( E = S, Se) with GaCl 3 in thf as solvent leads to the compounds [Cp 2 (CO) 4 Mo 2 E Sb]GaCl 4 . [Cp 2 (CO) 4 Mo 2 SSb]GaCl 4 crystallizes in the monoclinic system, space group P 2 1 /c with a = 815.64(6), b = 1094.31(5), c = 2503.7(2) pm, and β = 92.505(6)°. The selenium derivative [Cp 2 (CO) 4 Mo 2 SeSb]GaCl 4 forms isotypic crystals with a = 811.53(4), b = 1103.90(6), c = 2511.2(1) pm, and β = 92.704(4)°. Both the derivatives display ionic structures consisting of separated [Cp 2 (CO) 4 Mo 2 E Sb] + cations and GaCl 4 – anions. According to the 18 electron rule the [Cp 2 (CO) 4 Mo 2 E Sb] + cations can be considered as electron precise tetrahedral clusters, which are closely related to the well‐known dipnictogen complexes [Cp 2 (CO) 4 Mo 2 E 2 ] ( E = P, As, Sb, Bi).