1,2-Addition imido complex

With the same tactic, a meta-stable 3-coordinate iron(III) imido complex was reported by Holland and coworkers [40]. Using the diketiminate-supported dinitrogen iron(I) complex [L T eNNFeU ] as a source of iron(I) precursor [L = 2,4-bis (2,6-diisopropylphenylimino)pent-3-yl], the addition of adamantyl azide (AdN3) in... 

Organometallic complexes of the /-elements have been reported that will perform both intra-and intermolecular hydroamination reactions of alkenes and alkynes, although these lie outside of the scope of this review.149-155 Early transition metal catalysts are not very common, although a number of organometallic systems exist.156-158 In these and other cases, the intermediacy of a metal imido complex LnM=NR was proposed.159,160 Such a species has recently been isolated (53) and used as a direct catalyst precursor for N-H addition to alkynes and allenes (Scheme 35).161,162... 

The addition of electrophilic agents to terminal nitride ligands can be applied to the synthesis of imido complexes. This has been demonstrated with triphenylcarbonium salts and compounds of the formula [Re NC(C6H5)3 X4] (X = C1, Br, F, NCS) have been studied by EPR spectroscopy and show similar spectroscopic features to their [Re NB(C6F5)3 X4] analogues. " ... 

The lone structurally characterized imido complex is MoO(NH)Cl2(OPEtPh2)2.270 Here the oxo and imido ligands are cis to each other with Mo—0=1.66 and Mo—N = 1.70A, respectively. The N—H hydrogen has been located and the Mo—N—H angle is 157°. The orange-yellow complex was prepared by the reaction of MoOCl3 with Me3SiN3 followed by the addition of the tertiary phosphine oxide.270... 

The latter transformation requires the use of a small amount of an acid or its ammonium salt. By using [Cp2TiMe2] as the catalyst, primary anilines as well as steri-cally hindered tert-alkyl- and sec-alkylamines can be reacted.596 Hydroamination with sterically less hindered amines are very slow. This was explained by a mechanism in which equlibrium between the catalytically active [L1L2Ti=NR] imido complex and ist dimer for sterically hindered amines favors a fast reaction. Lantha-nade metallocenes catalyze the regiospecific addition of primary amines to alkenes, dienes, and alkynes.598 The rates, however, are several orders of magnitude lower than those of the corresponding intramolecular additions. 

A series of tantalum imido complexes has been synthesized by the addition of imines or nitriles to tantalum neopentylidene complexes as shown in Eq. (76). 

Figure 3. Electrophilic additions to an ri -pyrrolyl imido complex.

The ruthenium sulfoximido complex HRu3(C0)9 NS(0)MePh is of note because it formally has two electrons fewer than the normal tetrahedral structure [Eq. (64)].170 Upon addition of CO it is converted into an electron-precise /a-imido complex [Eq. (65)170]. 

The complexes will effect oxyamination reaction with alkenes in a stereospecific reaction (Scheme 8).290 After reductive cleavage of the intermediate alkanolaminato complex (I) (see below) vicinal amino alcohols (II) are formed. The reaction is unusual in that the new C—N bond is always formed at the least substituted terminal alkenic carbon atom, and there is a clear preference for the imido complex to use its NR group for coordination to the osmium despite the steric restraints of R.299,300 However, the least sterically hindered part of the alkene moiety is attached to. the nitrogen atom.290,291,300 The yields of amino alcohols in the reaction can be improved by addition of tertiary alkyl bulkhead amines (see below). 

A mononuclear imido complex of Zr has been prepared by reaction of LiNH(t-Bu) with ZrCl2(PhP(CH2SiMe2NSiMe2 CH2)2PPh) (ZrCl2(P2N2)) followed by addition of MeLi. In the formation of Zr(N-t-Bu)(P2N2), there was no evidence that the putative Zr(NH(t-Bu))Me(P2N2) was stable with respect to alkane elimination. ... 

Early-late heterobimetallic bridging imido complex CpjZrl/r-NBu lIrCp 1251 was synthesized in 65% yield by the sequential addition of BunLi and CpTr(NBu ) to Cp2ZrCl2.952 The Zr-Ir bond distance as determined by X-ray... 

Bergman has also reported an example of C-H addition to a zirconium-nitrogen double bond. The complex Cp2Zr(NHR)Me loses methane to generate an imido complex that can either be trapped with THF or reacted with benzene (Eq. 19). No reactions with alkanes were reported [86]. 

SCHEME 11.36 1,2-CH addition reactions have been observed with d° imido complexes and... 

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