Thiometalate ligands

Heterometallic clusters from thiometalate ligands by unit construction and the possibility of... 

Table 1 Multimetal Complexes with Thiometalate Ligands (Averaged M—S and M [ M Distances in Ay ...

It is worth noting that one thiometalate ligand provides six bonds to Cu and Ag atoms in the cage structure compounds. 

Thiometalate ligands are coordinated via sulfur to soft cations such as Cu+, Ag+ and Au+. Thus, it has not yet been possible to prepare any compound of the structural type (c) with MOS3 ligands. Following this principle, using oxotrithiometalates, compounds with a cubane-like structure were deliberately prepared. 

Finally, the electrochemical data for the cobalt system enable evaluation of the effect on redox properties of the thiometalate ligands (TM) varying from M02S2- to MS2-. It is evident that an-increasing oxygen content of the ligand makes the reduction more difficult. 

For aspects of complex formation it is important to realize that thiometalates are not very stable in aqueous solution, especially at low pH. Their decomposition may be caused by hydrolysis to oxometalates, by intramolecular redox processes, or by their marked tendency to form sulfides. With molybdates and tungstates the stability decreases with increasing oxygen content and increasing electron density on the ligands. When they decompose in acid media, binary sulfides (or with selenometalates, selenides) such as MoS3 are formed. 

EH-SCCC-MO calculations on the diamagnetic polythiometalates M3XSg (X = O, S) also show that these can be described as coordination compounds of MIVX2+ with MS4- ligands. For instance, an occupied MO is about 50% localized on the central W atom, but owing to the appreciable (ca. 20%) participation of the outer orbitals of W atoms there is a clear metal-metal interaction comparable to the M -TM interaction in heteronuclear systems (TM = thiometalate).]... 

The oxygen atoms of M04 can be replaced successively by sulfur, and all four thiometallates, MOsS ", M02S2 , MOSs " and MS4 have been prepared the thiomolybdates a century ago. They are useful reagents for the preparation of metal-sulfur clusters, and act as ligands, usually chelating but also as bridging groups. 

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