Sulfur bridges transition metals

Although the study of sulfur dioxide-transition metal coordination chemistry is an area of relatively recent intensive pursuit, structural information now spans a large number of stereochemically distinct coordination situations. The types of M-SO2 binding which have been identified, excluding insertion compounds and compounds containing SO2 bridging metal centers, are shown in Fig. 1. Several examples of complexes containing each type... 

The S02 molecule has unshared pairs of electrons on both the sulfur and oxygen atoms. As a result, it forms numerous complexes with transitions metals in which it is known to attach in several ways. These include bonding through the sulfur atom, through an oxygen atom, by both oxygen atoms, and various bridging schemes. In most cases, the complexes involve soft metals in low oxidation states. Another important reaction of sulfur dioxide is known as the insertion reaction, in which it is placed... 

Phosphoryl fluoride reacts as a base and, with BF , AsF5, and SbF5, oxygen-bridged 1 1 adducts are produced (88, 89). In liquid sulfur dioxide POF3 is weakly basic and it was in such a medium that the first transition-metal complex of this oxide fluoride, [Mn(OPF j)4]2v[AsF6l2, was produced in 1979 via the intermediate Mn(S02)v 2 AsFe]2 (90). 

This synthesis can be extended to the preparation of the sulfur nitride complexes of other transition and post-transition metals. Furthermore, Ni(S2N2H)2 can serve as a starting material for the synthesis of many derivatives of this compound by replacement of the acidic N—H proton. Such compounds include substituents on one or two of the nitrogen atoms, as well as groups that bridge the cis-nitrogen atoms. 

The osmium carbyne complex 115 reacts with elemental sulfur, selenium, and tellurium to afford the complexes 135 in which the element atoms "bridge the metal-carbon triple bond [Eq. (123)] (56). Complex 115 also reacts with transition metal Lewis acids such as AgCl or Cul to give dinuclear compounds with bridging carbyne ligands. Reaction with elemental chlorine results in addition across the metal-carbon triple bond to generate the chlorocarbene osmium complex 136 [Eq. (124)]. 

---