Homoleptic complexes mercury

Vinyl complexes are typically prepared by the same methods used to prepare aryl complexes. Vinyl mercury compounds, like aryl mercury compoimds, are easily prepared (by the mercuration of acetylenes), and are therefore useful for the preparation of vinyl transition metal complexes by transmetallation. The use of vinyl lithium reagents has permitted the s rnthesis of homoleptic vinyl complexes by transmetallation (Equation 3.35). Reactive low-valent transition metal complexes also form vinyl complexes by the oxidative addition of vinyl halides with retention of stereochemistry about the double bond (Equation 3.36). Vinyl complexes have also been formed by the insertion of alkynes into transition metal hydride bonds (Equation 3.37), by sequential electrophilic and nucleophilic addition to alkynyl ligands (Equation 3.38), and by the addition of nucleophiles to alkyne complexes (Equation 3.39). The insertion of alkynes into transition metal alkyl complexes is presented in Chapter 9 and, when rearrangements are slower than insertion, occurs by s)m addition. In contrast, nucleophilic attack on coordinated alkynes, presented in Chapter 11, generates products from anti addition. 

Aqueous Cf and Hg2 or HCl and Hg20, precipitate white [Hg2Cl2], calomel , soluble in concentrated Cr. This separates Hg2 sharply from Hg°. Mercury(II) oxide etc. are soluble in Cf, Br and r, forming numerous homoleptic and mixed complexes up to [HgX4] , and many salts some stabilities are [HgCU] " < [HgBr4] -<[Hgl4] -. 

Hydrogen-deuterium exchange is catalysed by an unusually stable mercury-toluene complex that contains a GaMe3 moiety. The first homoleptic platinum complex with terminal and bridging Cp Ga ligands has also been made. This is the compound [Pt2(GaCp )2( i2-GaCp )3]. 

---