Phosphorescent Complexes of {Mo₆I₈}⁴⁺ and {W₆I₈}⁴⁺ with Perfluorinated Aryl Thiolates featuring Unusual Molecular Structures

Abstract

Dedicated to Professor Rinaldo Poli on the occasion of his 65th birthday.A series of six novel cluster complexes [M 6 I 8 (SAr f ) 6 ] 2À (M=Mo or W; SAr f = p-SC 6 F 4 -C 6 F 5 , p-SC 6 F 4 Cl, or p-SC 6 F 4 CF 3 ) was prepared by exchange reactions between [Mo 6 I 14 ] 2À or [W 6 I 14 ] 2À and silver salts of the corresponding thiols and characterized by X-ray single-crystal diffraction and elemental analysis, NMR, ESI-MS, and CV techniques. In the crystal structures all the thiolate ligands adopt an idiosyncratic orientation along one of the idealized three-fold axes passing through two opposite μ 3 -I ligands and the centers of two opposite faces of the M 6 octahedra. This leads to shortened intramolecular C•••I distances inside the cluster below 3.5 Å. The clusters exhibit red photoluminescence with relatively high quantum yield, up to 0.42 in the case of (Bu 4 N) 2 [W 6 I 8 (SC 6 F 4 CF 3 ) 6 ]. Moreover, all the compounds exhibit X-ray luminescence; the close values of the maxima in the photo-and X-ray induced emission spectra indicate that the luminescence is cluster-centered.

Improved Synthesis of (TBA)2[W6Br14] Paving the Way to Further Study of Bromide Cluster Complexes

“…Previously, a study of the X-ray-induced luminescence of tungsten cluster complexes was carried out for compounds with the {W 6 I 8 } 4+ core in comparison with molybdenum counterparts. 63,77 In our work, X-ray luminescence was shown for the first time for complexes with the {W 6 Br 8 } 4+ core using (TBA) 2 [W 6 Br 8 X 6 ] (X = Cl, Br, I) as an example. The substances were prepared in the form of thin strips of crystalline powder of the same area and thickness as those deposited on adhesive tape and irradiated with unfiltered X-ray bremsstrahlung with a maximum energy of 40 keV.…”

Molecularly Engineered Room-Temperature Phosphorescence for Biomedical Application: From the Visible toward Second Near-Infrared Window

“…In sharp contrast with common organic molecules, which are primarily excited singlet state emitters, transition metal complexes prefer to decay from excited triplet states and hence can release efficient room-temperature phosphorescence . By sorting out related documents, transition metals for triplet science studies mainly include group VI (Mo and W), VII (Re), and XI (Cu, Ag, Au) elements. − More recently, the coordination of organic ligands with common transition metal ions (e.g., Zn 2+ ) has been proven to be an effective method to realize high-efficiency yellow phosphorescence . These intriguing photoluminescent properties will define their potential applications as emitters for biosensing and bioimaging .…”