1.1- Dithio complexes group

Numerous synthetic and crystallographic studies of the Group V 1,1-dithio complexes have been reported in the literature since 1970. 

Selected Structural Parameters of the Group V Transition Element 1,1-Dithio Complexes. 

Another example of a ring contraction is shown in Scheme 10. It is postulated that both dithio-carbonyl groups in macrodithiolactone (81) are reduced to generate a diradical which couples to form a bicyclic product (82), subsequent S-alkylation, followed by removal of the sulfur groups complete the sequence. The overall yield of the fused product (83) is ca. 50%. Similar schemes have been used to build more complex polycyclic ring systems <90JA3040>. 

In nickel and palladium dithiobenzoato complexes, four-membered chelate rings are formed (366), whereas, in the corresponding phenyl-dithio acetates [M2(S2CCH2Ph)4], the dithio ligands act as bridging groups between the two metal atoms, with the formation of binuclear units (367). The molecular structure of the latter compounds shows that each metal atom is coordinated to four sulfur atoms and to the other metal atoms in a square-pyramidal geometry. Other evidence for... 

The complexes of the 1,1-dithio ligands with the Group I transition metals have been studied in considerable detail, and have been extensively reviewed by Coucouvanis (1). Interest in the synthetic chemistry of these complexes has been maintained over recent years, but a large proportion of the work on these complexes has been concerned with physical studies, particularly by esr spectroscopy. 

M(dmit)2 complexes (dmit = C3S52- = l,3-dithiole-2-thione-4,5-dithio-late) constitute one of the most important subclasses. The most studied metal complexes are those of group 10 (Ni, Pd, Pt), which possess a square-planar geometry see for instance the molecular structure of the monoanion [Ni(dmit)2], Figure 42.73... 

Recently, dithio-diolate ligands have been employed for construction of group 4 metal catalysts for the ROP of lactide. These metal dithiolate complexes form mononuclear species of the type [(OSSO)M(OR)2] with an octahedrally coordinated metal center. These fluxional compounds acted as highly active catalysts in the ROP of L- and rac-lactide. Hafnium complexes were also introduced as initiators for the ROP of L-lactide and rac-lactide (vide infra) in very limited cases. To our knowledge, the hafnium derivative 146 displayed the highest activity among the group 4 catalysts reported to date (complete conversion of 300 equiv. of... 

A variety of organometallic compounds of Sn(IV) and Pb(IV) with 1,1-dithio ligands have been reported. The interesting MeSn(Et2Dtc)3 complex is cited (467) to have a pentagonal bipyramidal structure. The axial Sn-S distance opposite to the methyl group is 0.21 A shorter than the equatorial Sn-S distances. 

However, on the basis of N-benzoylthiourea 540, not only chelating complexes of type 541 can be synthesized, but also molecular compounds as shown by 542 [938]. In the case of compound 542 (M = Pt) being formed, 540 takes part as a monoden-tate S-donor ligand. In this respect it has to be noted that other 0,S-containing ligands can participate only as S-donors. In particular, dithio-oxalic acid 543 is assumed to belong to this group complexes of type 544 have been obtained on its basis [1, vol.2] ... 

---