Applications of Cd N.M.R. to Polycadmium Complexes. IV. Reactions of [Cd₁₀(SCH₂CH₂OH)₁₆]⁴⁺ With Chloride Ion, and the Crystal and Molecular Structure of Hexadeca(2-Hydroxyethanethiolato)-Tetrachloro-Decacadmium [Cd₁₀(SCH₂CH2OH)₁₆Cl₄]

Abstract

Reaction of [Cd₁₀(SCH₂CH₂OH)₁₆]⁴⁺ (ClO₄^-)(1) with chloride ion in dimethylformamide produces Cd₁₀(SCH₂CH₂OH)₁₆Cl₄ (4). Crystalline (4) [P bcn, a 14.802(3), b 24.950(5), c 20.891(4) Ǻ, 2032 observed data (Mo Kα ), R 0.047] contains molecular aggregates (symmetry exactly 2, approximately 4) in which the Cd₁₀S₁₆ core is similar to that of (1), but which differ in that eight instead of sixteen of the ligand hydroxy functions are coordinated in (4). Six inner Cdⁱ atoms occur in pseudo- octahedral array, four with Cdⁱ (SR)₄(OH) coordination involving chelation of μ₃-SCH₂CH₂OH [as in (1)], while the other two are six- coordinate Cdⁱ (SR)₄(OH)₂ in an unusual stereochemistry which arises by partial transverse addition of a pair of hydroxy functions across an edge of the tetrahedral Cdⁱ (SR)₄ site of (1). The four Cd^O atoms of (4) each possess tetrahedral (SR)₃Cd^OCl coordination.

¹¹³Cd n.m.r . spectra of mixtures of (1) and Cl ^- in dimethylformamide reveal ( i ) the progress of the change (1)→(4) and correlation of chemical shifts with the five different cadmium sites; (ii) the rapid interchanges of Cdⁱ sites in (4) and between (4) and (1), interchanges which are slowed to <10⁴ s^-1 at <c. 230 K; (iii) modifications of the dynamics of Cdⁱ site interchange caused by relatively small proportions of Cl ^-; and (iv) interconversion of Cd^O sites between (4) and (1).