US EPA

4023443 

Journal Article 

Imido-Titanium/Molybdenum Heterobimetallic Systems. Switching from eta(6)-Arene to Fischer-Type Aminocarbene Complexes by Tuning Reactivity Conditions 

Lorber, C; Vendier, L 

2010 

1 

Organometallics
ISSN: 0276-7333
EISSN: 1520-6041 

29 

5 

1127-1136 

10.1021/om900825a 

WOS:000274841600011 

Two types of bimetallic titanium/molybdenum systems are described: the first possesses unprecedented eta(6)-arene-imido groups, while the second has Fischer-type aminocarbene ligands bridging the two metals. The (eta(6)-arene)-Mo imido-Ti complex Ti[=(eta(6)-Ar)Mo(CO)(3)]Cl-2(NHMe2)(2) (2; Ar = 2,6-Pr-i(2)-C6H3) has been prepared through the reaction of (eta(6)-ArNH2)Mo(CO)(3) (3) and TiCl2(NMe2)(2). The alternative route from 2 and Ti(NMe2)(4)/Me3SiCl also afforded 1, but it was contaminated with a small amount of Ti(=NAr)Cl-2(NHMe2)(2) (1). The reaction between the dimeric complexes {Ti(mu-NAr)(NMe2)(2)}(2) and Mo(CO)(6) gave complex mixtures of products, among which the Fischer-type aminocarbene complex [(CO)(5)Mo{=C(NMeCH2NMe2)O}Ti(=N-2,6-Pr-2(i)-C6H3)(NMe2)(NHMe2)] (4) could be characterized. The formation of 4 resulted from the nucleophilic attack of the amido -NMe2 to the carbonyl that afforded the titanoxy aminocarbene linker between the Mo and the Ti centers, followed by a subsequent C-H activation of a methyl group of the aminocarbene and C,N coupling with an amido ligand on titanium. Treatment of Ti(NMe2)(4) with 1 equiv of Mo(CO)(6) produced the titanoxy aminocarbene [(CO)(5)Mo{=C(NMe2)O}Ti(NMe2)(3)] (5), while in the presence of 1 equiv of ArNH2 the imido complex [(CO)(5)Mo{=C(NMe2)O}Ti(=N-2,6-Pr-2(i)-C6H3)(NMe2)(NHMe2)(2)] (6) is formed. The molecular structures of 1-6 have been determined by X-ray diffraction.