Template synthesis of polyiodide belt at a metal complex cation: structure of [([16]aneS 4 )M–I–M([16]aneS 4 )] 3+ [I 5 – ] 2 i – (M = Pd, Pt) incorporating a symmetric linear M–I–M bridge ([16]aneS 4 = 1,5,9,13-tetrathiacyclohexadecane)

Reaction of [M([16]aneS4)][PF6]2 with NBun4I3 affords the binucleas species [([16]aneS4)M–I–M([16]aneS4)]3+(M = Pd, Pt) incorporating a highly unusual linear M–I–M moiety within a conformationally constrained environment: the counter anion, which can be regarded formally as two I5– and One I– or alternatively as two I3–, two I2 and one I–, forms a belt around the complex cation with the metal-bridging I– placed at its centre.