Vinyl-Metal Complexes by

if cr-Vinyl-Metal Complexes by Addition of HX to if rr-Alkyne Complexes 

For synthesizing alkenyl-transition-metal complexes (see also 5.8.2.7.3), the addition of HX to -acetylene complexes is applied to jj -alkynePt-complexes  

When terminal alkynes are used, the hydrogen adds to the carbon bearing more hydrogens i.e., PtE(CR=CH2)(PPh3)2 complexes are obtained (R = Me, Et, Ph or p-tol E = Cl, Br, NO3 or OCOCF3). 

Furthermore, the reaction of Pt[(p-tol-C=CH)](PPh3)2 with DCl forms an alkenyl complex in which the deuterium is exclusively cis to platinum. 

Further reaction of the cr-alkenyl complexes with xs HX forms the corresponding olefin together with L2PtX2 since both cis- and trans-olefin are obtained the solvolysis of vinyl complexes may not occur with retention of configuration about the double bond .  

---