Synthesis, Updated Characterization, and Reactivity of Low‐Valent Titanocene Complexes
Griffin J. LaChapelle, James F. Britten, David J. H. EmslieUpdated syntheses and/or structural characterizations are provided for previously reported halotitanocene(III) complexes [{Cp 2 Ti(μ‐X)} 2 ] (X = Cl ( 1 ), Br ( 2 ), and I ( 3 )), and THF‐coordinated [Cp 2 Ti(μ‐Cl)(THF)ZnCl(μ‐Cl) 2 TiCp 2 ] ( 4 ) was crystallographically characterized. Reactions of 1 with ClAlR 2 Lewis acids generated the heterobimetallic complexes [Cp 2 Ti(μ‐Cl) 2 AlR 2 ] (R = Cl ( 5a ), Me ( 5b ), Ph ( 5c ), C 6 F 5 ( 5d )) and reactions of 1 with M[BAr 4 ] (M = Na, K or Tl) salts in DME afforded the DME‐coordinated cations [Cp 2 Ti(κ 2 ‐DME)][BAr 4 ] (Ar = C 6 F 5 ( 6a ), 3,5‐C 6 H 3 (CF 3 ) 2 ( 6b ), 3,5‐C 6 H 3 Cl 2 ( 6c )). Reaction of the titanacyclopropene [Cp 2 Ti(η 2 ‐C 2 (SiMe 3 ) 2 )] with PhC 2 P i Pr 2 afforded the phosphine‐containing titanacyclopropene complex [Cp 2 Ti(η 2 ‐PhC 2 P i Pr 2 )] ( 7 ), and the triisobutylaluminium adduct of this species, [Cp 2 Ti{η 2 ‐PhC 2 P i Pr 2 (Al i Bu 3 )}] ( 8 ), was crystallographically characterized. Addition of 2 equiv. of KC 8 to a solution of the zwitterionic titanocene(III) complex [Cp{η 5 :κ 2 F 2 ‐C 5 H 4 B(C 6 F 5 ) 3 }Ti] in THF yielded [K(THF) 3 ][Cp{η 5 :κ 1 C ‐C 5 H 4 B(C 6 F 5 ) 2 (C 6 F 4 )}Ti(THF)] ( 9 ), likely resulting from 1‐electron reduction to titanium(II) followed by C─F bond oxidative addition to form a titanium(IV) fluoride species, KF elimination, THF coordination, and a second 1‐electron reduction to titanium(III).