Synthesis and Crystal Structure of the Azide K4[Re6Sei8(N3)a6]*4H2O; Luminescence, Redox, and DFT Investigations of the [Re6Sei8(N3)a6]4- Cluster Unit
Résumé
The reaction of K4[Re6Sei8(OH)a6]*8H2O with NaN3 in water results in the formation of [Re6Sei8(N3)a]4- units that crystallize with K+ and H2O to form K4[Re6Sei8(N3)a6]*4H2O [P21/c (N°14), a = 9.0595(3) Å, b = 13.2457(4) Å, c = 13.2040(5) Å, β = 94.472(1)°]. In the solid state, the unit is characterized by N3 linear groups forming bond angles of roughly 120° with the Re6 cluster. The positions of the νas and νsy bands as well as N-N-N deformation modes of the N3 groups are discussed. Luminescence properties of the [Re6Sei8(N3)a]4- unit were measured in the solid state and in an acetonitrile solution. The redox potential of the [Re6Sei8(N3)a]4-/[Re6Sei8(N3)a]3- system was measured in acetonitrile. Experimental results were analyzed in the light of density functional theory calculations.