Preparation, photoluminescence and excited state properties of the homoleptic cluster cation [(W 6 I 8 )(CH 3 CN) 6 ] 4 .

Solvated tungsten iodide cluster compounds are presented with the homoleptic cluster cation [(W 6 I 8 )(CH 3 CN) 6 ] 4+ and the heteroleptic [(W 6 I 8 )I(CH 3 CN) 5 ] 3+ , synthesized from W 6 I 22 in acetonitrile. Crystal structures were solved and refined on deep red single-crystals of [(W 6 I 8 )(CH 3 CN) 6 ](I 3 )(BF 4 ) 3 ·H 2 O, [(W 6 I 8 )I(CH 3 CN) 5 ](I 3 ) 2 (BF 4 ), and on a yellow single-crystal of [W 6 I 8 (CH 3 CN) 6 ](BF 4 ) 4 ·2(CH 3 CN) on the basis of X-ray diffraction data. The structure of the homoleptic [(W 6 I 8 )(CH 3 CN) 6 ] 4+ cluster is based on the octahedral [W 6 I 8 ] 4+ tungsten iodide cluster core, coordinated by six apical acetonitrile ligands. The electron localisation function of [(W 6 I 8 )(CH 3 CN) 6 ] 4+ is calculated and solid-state photoluminescence and its temperature depedence are reported. Additionally, photoluminescence and transient absorption measurements in acetonitrile are shown. Results of the obtained data are compared to compounds containing [(M 6 I 8 )I 6 ] 2- and [(M 6 I 8 )L 6 ] 2- (M = Mo or W; L = ligand) clusters.