Reactivity of coordinated Ph₂P(C₅H₅). Preparation of M(CO)_6-n[Ph₂P(C₅H₄Tl)]_n complexes (M = Cr, Mo; n = 1, 2)

The interaction of C₇H₈Cr(CO)₄ with two equivalents of Ph₂P(C₅H₅) in hexane at 0°C gives trans-Cr(CO)₄[Ph₂P(C₅H₅)]₂ (I) in high yield (80%). In CDCl₃ at 30°C, I isomerizes to cis-Cr(CO)₄(Ph₂PC₁₀H₁₀PPh₂) (II) quantitatively. Compound II can also be prepared in high yield (85%) by the interaction of trans-Cr(CO)₄(Ph₂PCl)₂ with two equivalents of TI(C₅H₅) in refluxing toluene. Treatment of M(CO)₆ (M = Cr, Mo) with one equivalent of trimethylamine N-oxide in THF followed by the addition of one equivalent of Ph₂P(C₅H₄Tl) affords M(CO)₅[Ph₂P(C₅H₄Tl)] (III, M = Cr; IV, M = Mo) and M(CO)₄ [Ph₂P(C₅H₄Tl)]₂ (V, M = Cr; VI, M = Mo). M(CO)₄[Ph₂P(C₅H₄Tl)]₂ adopts a trans- and a cis-configuration for chromium and molybdenum, respectively. The M(CO)₄[Ph₂P(C₅H₄Tl)]₂ complex can also be prepared conveniently either by the interaction of C₇H₈]M(CO)₄ with two equivalents of Ph₂P(C₅H₄Tl) or by the interaction of M(CO)₄[Ph₂P(C₅H₅)]₂ with two equivalents of Tl(OEt) in THF. © 1992.