THE CRYSTAL AND MOLECULAR STRUCTURE OF DECACHLORO -μ-1, 4, 8, 11-TETRATHIACYCLOTETRADEC-ANEDINIOBIUM(V). AN ADDUCT OF NbCl₅ WITH AN “INSIDE-OUT” BRIDGING MACROCYCLIC LIGAND

Abstract

The crystal and molecular structure of decachloro-μ-1,4,8,11-tetrathiacyclotetradecanediniobium(V) is reported. This is the first example of a complex in which such a macrocycle adopts an inside-out or exo configuration. (NbCl₅)₂-(S₄-e-pr[14]) crystallizes in space group P2₁/n with two complex molecules and two solvent benzene molecules per unit cell of dimensions a = 7.925(6) Å, b = 19.516(11) Å, c = 10.212(5) Å, and β = 88.62° (5). Full matrix least squares refinement gave final discrepancy factors of R₁ = 0.109 and R₂ = 0.127 for 1061 data having F² < 3[sgrave](F²). The molecular structure consists of two NbCl₅ units bridged through sulfur by the macrocycle with two of the four sulfur atoms uncoordinated. The macrocyclic ring is substantially disordered. The implications of this structure for bonding in macrocyclic complexes is discussed and the possible significance to kinetic studies of macrocyclic complexes is explored.