Organosilyl Transition Metal Derivatives

Compounds of this type have been known since 1956, and have been described in large numbers. They are formed by hydrosilation in situ. 

Bis(triphenylphosphine) (dichloromethylsilyl)hydroplatinum [455] (m.p. 210-215°C) can be isolated if the silylation of hexene(l) with dichloromethylsilane has been catalysed by ethene bis(triphenylphosphine)platinum. The following structures of these derivatives are typical  

The following oxidation levels are observed in the metals a-bonded to the silicon 

The silicon-metal bond is stabilized by the neutral (e.g. triorganophosphine, CO), or ionic (e.g. cyclopentadienyl) ligands on the transition metal atom. The electronegative groups on the silicon atom reinforce this effect the degree of stabilization decreases in the following sequence [456] 

The stabilities of silicon-metal bonds vary the most stable are those with Mn, Fe and Pt, while those with Cr, Mo and W are unstable. 

---

Organosilyl substituted 7)5-cyclopentadienyl complexes may be prepared by two main procedures (a) reactions of silylated cyclopenta-dienes or their alkali metal derivatives, with an appropriate transition metal compound (carbonyl or halide) with formation of ir-bonds (b) metalation of a preformed 7j5-cyclopentadienyl complex, followed by treatment with an organohalosilane. 

---