Compounds with Cluster Cations together with Cluster Anions [(M6X12)(EtOH)6]2+ besides [(Mo6Cl8)Cl4X2]2- (M = Nb, Ta; X = Cl, Br) - Synthesis and Crystal Structures

Abstract

Compounds consisting of both cluster cations and cluster anions of the composition [(M6X12)(EtOH)6][(Mo6Cl8)Cl4X2] · n EtOH · m Et2O (M = Nb, Ta; X = Cl, Br) have been prepared by the reaction of (M6X12)X2 · 6 EtOH with (Mo6Cl8)Cl4. IR data are given for three compounds. The structures of [(Nb6Cl12)(EtOH)6][(Mo6Cl8)Cl6] · 3 EtOH · 3 Et2O 1 and [(Ta6Cl12)(EtOH)6][(Mo6Cl8)Cl6] · 6 EtOH 2 have been solved in the triclinic space group P1 (No. 2). Crystal data: 1, a = 10.641(2) A, b = 13.947(2) A, c = 15.460(3) A, α = 65.71(2)°, β = 73.61(2)°, γ = 85.11(2)°, V = 2005.1(8) A3 and Z = 1; 2, a = 11.218(2) A, b = 12.723(3) A, c = 14.134(3) A, α = 108.06(2)°, β = 101.13(2)°, γ = 91.18(2)°, V = 1874.8(7) A3 and Z = 1. Both structures are built of octahedral [(M6Cl12)(EtOH)6]2+ cluster cations and [(Mo6Cl8)Cl6]2– cluster anions, forming distorted CsCl structure types. The Nb–Nb and Ta–Ta bond lengths of 2.904 A and 2.872 A (mean values), respectively, are rather short, indicating weak M–O bonds. All O atoms of coordinated EtOH molecules are involved in H bridges. The Mo–Mo distances of 2.603 A and 2.609 A (on average) are characteristic for the [(Mo6Cl8)Cl6]2– anion, but there is a clear correlation between the number of hydrogen bridges to the terminal Cl and the corresponding Mo–Cl distances.