Imido titanium compounds

See, e.g.. Fix, R. M. Gordon, R. G. and Hoffman, D. M., Synthesis of thin films by atmospheric pressure chemical vapor deposition using amido and imido titanium(IV) compounds as precursors. Chem. Mater. 2 (1990) 235-241. 

Thiolato titanium complexes have been developed supported by Cp and phosphinimido ligands, in an attempt to compare their chemical behavior with the corresponding bis-Cp derivatives, using the steric and electronic analogy between Gp and imido functionalities. Compounds of the type CpTi(N=PPr13)(SR2)2 (Scheme 244) are prepared by reaction of the dichloro complex with the corresponding lithium thiolates LiSR, or alternatively by protonolysis of Ti-Me... 

Reaction of the Cp-amidinato imido titanium complexes Cp Ti[MeC(NPr1)2](NR) (R = But, 2,6-C6H3Me2) with C02 proceed via initial cycloaddition reactions to give N-O-carbamato complexes. The Buc derivative does not react with an excess of C02 and it undergoes a retrocyclization process with the formation of BuNCO and the binuclear fi-oxo compound Cp Ti[MeC(NPr1)2] 2(/i-0). The aryl derivatives exhibit a double CO2 insertion process to give Cp Ti[MeC(NPri)2][0(C0)N(Ar)(C0)0] (Scheme 248).661... 

The Cp Ti(amidinate) fragment provides a particularly useful platform for the synthesis of novel titanium imido complexes and the study of their unusual reactivity. Numerous single-, double-, and cross-coupling and imido-transfer reactions were investigated using these compounds. The synthetic routes leading to CpTi and Cp Ti amidinate derivatives are outlined in Scheme... 

The nudeophile is activated by the formation of a titanium(IV)-imido complex 19. The next step is a [2 + 2] cydoaddition with one of the jt-bonds of the allene, depending on the regioselectivity leading to either 20 or 22. Compound 20 then delivers 21 by twofold stepwise proto-demetallation and the latter enamine tau-tomerizes to the imine 24 (Scheme 15.3). Compound 22, on the other hand, should provide allylamines 23, but as we shall see, there are no examples of that mode of reaction known so far. 

Imidazolium ligands, in Rh complexes, 7, 126 Imidazolium salts iridium binding, 7, 349 in silver(I) carbene synthesis, 2, 206 Imidazol-2-ylidene carbenes, with tungsten carbonyls, 5, 678 (Imidazol-2-ylidene)gold(I) complexes, preparation, 2, 289 Imidazopyridine, in trinuclear Ru and Os clusters, 6, 727 Imidazo[l,2-a]-pyridines, iodo-substituted, in Grignard reagent preparation, 9, 37—38 Imido alkyl complexes, with tantalum, 5, 118—120 Imido-amido half-sandwich compounds, with tantalum, 5,183 /13-Imido clusters, with trinuclear Ru clusters, 6, 733 Imido complexes with bis-Gp Ti, 4, 579 with monoalkyl Ti(IV), 4, 336 with mono-Gp Ti(IV), 4, 419 with Ru half-sandwiches, 6, 519—520 with tantalum, 5, 110 with titanium(IV) dialkyls, 4, 352 with titanocenes, 4, 566 with tungsten... 

Whereas Groups 5-7 metals form numerous complexes with M=E double bonds, this feature has been less prominent in Group 4. However, an increasing number of titanium imido compounds have recently been prepared 41... 

See, for example, the following sources and references therein a) M. P. Doyle, M. A. McKervey, T. Ye, Modern Catalytic Methods for Organic Synthesis with Diazo Compounds, Wiley, New York (1998). b) J. L. Poise, A. W. Kaplan, R. A. Andersen, R. G. Bergman, Synthesis ofan n2-N2-titanium diazoalkane complex with both imido-like and metal carbene-like reactivity patterns, J. Am. 

After the Ziegler-Natta classical catalysts, other kind of metallic complexes were reported for the polymerization of butadienes, such as Ni-based catalysts, halfsandwich titanium complexes, or transition-metal imido compounds activated with Bp30Et2, AlEt3, B(CgF5)4, or MAO [3]. 

Imido and 0x0 compounds are intermediates in many of the transfers of oxygen atoms and nitrene units to olefins to form epoxides and aziridines, and they are intermediates in many of the insertions of oxygen atoms and nitrene units into the C-H bonds of hydrocarbons to form alcohols and amine derivatives. The enantioselective epoxidation of allylic alcohols (Scheme 13.22) " is the most widely used epoxida-tion process, and the discovery and development of this process was one of the sets of chemistry that led K. Barry Sharpless to receive the Nobel Prize in Chemistry in 2001. The mechanism of this process is not well established, despite the long time since its discovery and development. Nevertheless, most people accept that transfer of the oxygen atom occurs from a titanium-peroxo complex - rather than from an 0x0 complex. Jacobsen s and Katsuki s - manganese-salen catalysts for the enantioselective epoxidations of unfunctionalized olefins, which were based on Kochi s achiral chromium- and manganese-salen complexes, are a second set of... 

This is a striking improvement over other fluorinating reagents. In addition, this elegant method of fluorination can be applied to complexes exhibiting an 0X0 or imido function and to titanium(III) compounds. 

DME) (10) was isolated (Scheme 5). The origin of the proton in 9 could not conclusively be determined and may result either from proton abstraction from the solvent or the coordinated hgand L. Both compounds react with MesSiCl to form the silylated titanium imido [LTi=NSiMe3]. 

Guiducci AE, Boyd CL, Clot E, Mountford P (2009) Reactions of cyclopentadienyl-amidinate titanium imido compounds with CO2 cycloaddition-extnision vs. cycloaddition-insertion. Dalton Trans 5960-5979... 

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