Amido complexes structure

The C-coordinated thiazolium complexes are the result of the proton-induced cyclization reactions (980M513). Thus, complex 1 on protonation with tetrafiuoroboric acid yields the C-coordinated thiazolium structure 2. In turn, the nitrile complex 3 under these conditions is transformed to the thiazolium cationic species 4. Protonation of the amido complex 5 with tetrafiuoroboric acid also results in a cyclization but it proceeds differently. The amino group of the CONH2 moiety is lost and BF3-framework is coordinated via the carbonyl oxygen in an overall neutral complex 6. 

Iridium chemistry also holds a rare example of a monodentate guanidinate ligand. The monomeric parent amido complex Cp Ir(PMe3)(Ph)(NH2) cleanly undergoes an insertion reaction on treatment with diisopropylcarbodiimide (Scheme 153). Spectroscopic data and an X-ray structural analysis revealed the presence of a nonchelating guanidinate ligand. ... 

Nin-amido complexes such as (117) react with small electrophiles by insertion either in the Ni—N bond (e.g., with C02 to form (118)) or in the N—11 bond. With unsubstituted aryl groups (Ar = Ar = Ph), both a monomeric complex (117) or a dimeric species (119) is formed, depending on the amount of PMe3 added. Using bulky borylamide ligands, an almost linear, two-coordinate Nin complex could be obtained and structurally characterized.467 The N—Ni—N angle in (120) is 167.9°. 

An EXAFS study of surface species [(=SiO)2Ta(=NH)(NH2)] yielded spectra that can be satisfactorily fitted by a model based principally on a Ta bissiloxy amido imido structure that yielded the bond distances of 1.787(19) A for Ta=N, 1.892(9) A for Ta-O and 1.97(3) A for Ta-N. These distances are in good agreement with values obtained from crystallographic data for molecular imido amido Ta(=N-) (-0-) (-N<)j, type complexes and fall within ranges usually observed for these distances. 

Complex alkoxides of the type [CsOR]n are known, structures of which have not been well defined. It reacts with amines forming amido complexes of the type CsNHR or CsNR2. The structures of crystalline complexes are complicated, depending upon the solvent and other factors. 

R = R = Cy R = 1-adamantyl, R = CfiH 5. Te2-3,5 5 ). The vanadium analogue of the latter [V N(l-Ad)(C6H3Me2-3,5) 3] " 4 has also been characterized. Furthermore, a more efficient route to [Cr N(SiMe3)2 3] and a new crystal structure determination has been described. Three-coordinate metal amides have been treated in a general review that covers three-coordinate transition metal species with hard ligands. The electronic structure and bonding in tricoordinate amido complexes of transition metals have also been detailed... 

This transformation is in contrast to the corresponding more sterically crowded [Mo N (Bu )Ar 3] which does not exhibit this type of behaviour. Initially it was assumed that the cyclometallated structure would inhibit the type of reactions (e.g. with N2 or N2O) shown by the t-Bu substituted tris-amido complex. Investigation of the chemistry, however, showed that this is not the case and the imine-hydrido product behaves as an effective source of [Mo N(Pr )Ar 3] which, because of its less sterically encumbered nature, exhibits reactivity not observed for its more hindered [Mo N(Bu )Ar 3] counterpart. A simple example is provided by complex formation with benzophenone to give [Mo N(Pr )Ar 3(r 2-OCPh2)], whereas the Bu analogue did not react with this reagent. ... 

The chemistry of indium complexes of aU types in metal oxidation states lower than +3 has been comprehensively reviewed. Few lower oxidation state mononuclear amido complexes of indium are well characterized, however, and no structure has been reported for an In(I) amide. The compound In N(SiMe3)2 n. which is unstable, " has been characterized NMR spectroscopy but its structure is unknown. The structures of several In(I) complexes, related to amides but outside our current scope, have been described. Like its aluminium and gallium counterparts, the p-diketuninate derivative [ In N(Dipp)C(Me) 2CH] has been characterized, as has the closely related species [ In N(Dipp)C(CF3) 2CH]. ° These feature V-shaped, two-coordination at the metal. The less bulky [(In N(Mes)C(Me) 2-CH)2] ° and 15-2.6-.Vlc,)( (Me) i are dimeric with long In In bonds of... 

The reaction of PtX and liquid ammonia gives mixtures of haloammine complexes [PtX (NH3)6 ]X4 n (X = Cl, Br, I n = 3, 2, 1, 0). The salts Pt(NH3)6]X, may be isolated as the main product only after several weeks of reaction. Interactions at room temperature of PtCl -and PtBr salts with liquid ammonia yield the dinuclear p-amido ammine complex [(NH3)4Pt(/i-NH2)2Pt(NH3)4]X6 quantitatively.1033 The structure shows a Pt-Pt separation of 3.16(1) A. 34 Interaction of PtXg with liquid or gaseous ammonia followed by addition of excess KNH2 yields the hexakis(amido) complex K2[Pt(NH2)6] (equation 333).1033 Complexes of the anionic ligand NC12 bonded to platinum(IV) have also been prepared. One method is by treatment of [PtCl(NH3)s]CI3 with chlorine (equation 334).1035... 

The chloro- and bromo-bridged complexes were first prepared by Werner (7). Werner originally formulated these complexes as singly bridged complexes (structure IX), but the /i-amido-/<-chloro and fi-amido-/i-bromo structures have recently been demonstrated by crystallographic studies (387, 388). The equilibrium constant Kl2 = Kt x K2 has been determined spectrophotometrically and the formation of structure X for X"- = Br is less favorable than its formation for the chloro analog (376, 379) (Table XXXVI). The equilibrium between... 

Reaction with N03 yields an aqua nitrato complex (structure IX), and Kx =0.022 M 2 (25°C, 2 M NaN03) has been determined spec-trophotometrically. At very high nitric acid concentration, evidence for another nitrato complex has been obtained and a /i-amido-/i-nitrato complex is considered more likely than, e.g., a dinitrato complex (385). 

When aqueous solutions of the complexes [Co(NH3)5(N=CR)]3+ (R=Me or Ph) are treated with an excess of NaN3 at pH 5-6 (to prevent base hydrolysis to the amido complex) tetrazole complexes are formed (Scheme 17).32 The formation of 5-methyltetrazoIe from sodium azide and acetonitrile requires a reaction time of 25 h at 150 °C323 compared with only 2 h at ambient temperature for coordinated acetonitrile. The subsequent conversion of the N -bonded complex to an N2-bonded complex has been confirmed as the latter complex has been prepared and its crystal structure determined.324... 

Hydrocarbonyl compounds, lanthanide complexes, 4, 4 ( -Hydrocarbyl)bis(zirconocene), preparation, 4, 906 Hydrocarbyl-bridged cyclopentadienyl-amido complexes, with Zr(IV), 4, 864 Hydrocarbyl complexes bis-Cp Ti hydrocarbyls reactions, 4, 551 structure and properties, 4, 551 synthesis, 4, 542 cobalt with rf-ligands, 7, 51 cobalt with rf-ligands, 7, 56 cobalt with ]4-ligands, 7, 59 cobalt with rf-ligands, 7, 71 heteroleptic types, 4, 192 homoleptic types, 4, 192 into magnetic metal nanoparticles via ligand stabilization, 12, 87 via polymer stabilization, 12, 87 into noble metal nanoparticles... 

Ruthenium amido complexes (137) effected asymmetric Michael addition of /S-keto esters (134) to cyclopent-2-en-l-one (135) to give quantitatively the corresponding Michael adducts (136) with excellent enantioselectivity (<97% ee), although with a 1 1 diastereoisomer ratio (Scheme 8). The stereochemical outcome of the reaction was significantly influenced by the structure of the catalysts (137) and /S-keto esters.170... 

Another mechanistically interesting example was reported by Ikariya et al. in 2003 (Scheme 10) [12], The authors focused on the basic character of the Ru-amido complex 21. The reaction of dimethyl malonate with 21 afforded a C-bound Ru-enolate, the structure of which was supported by X-ray analysis. It was considered that the N-H moiety plays a role in bringing the enones to the optimum position by hydrogen bonding, as shown in 22 C-C bond formation then occurs at relatively high reaction temperature, affording the desired adduct in 97 % ee. Before this report appeared, a related catalyst system had been examined by Suzuki et al. for the Type I reaction [4f]. 

R = alkyl, aryl) undergoes insertion reactions with C02, COS, CS2, and CSe2 to form carbamate complexes and reacts with alcohols to form alkoxide complexes. The structural motif of the amido complexes is highly dependent on the steric bulk of the R group. When R = phenyl, the complex is... 

Figure 4.7 The structure of complex Eu(7)2(dme)2 [11]. (Reproduced with permission from T.D. Tilley, A. Zalkin, R.A. Andersen and D.H. Templeton, Divalent lanthanide chemistry. Preparation of some four- and six-coordinate bis[(trimethylsilyl)amido] complexes of europium(II). Crystal structure of bis[bis(trimethylsilyl)amido]bis(l,2-dimethoxyethane) europiumll), Inorganic Chemistry, 20, 551, 1981. 1981 American Chemical Society.)...

A large number of structurally characterized bis(trimethylsilyl)amido complexes now exist Table 5 gives a representative selection of monometallic homoleptic compounds, both base-free and with coordinated ethers. Other examples are known with coordinated fiuorobenzenes, isonitriles,methylated pyridines, various amines (TMEDA, PMDTA, TMPDA (Tetra-methylpropylenediamine), BzNMe2 (benzyldimethylamine)), Ph PO, (Bu"0)(Pr )C0, and l,3-(Pr )2-3,4,5,6-tetrahydropyrimid-2-ylidene. Their structures illustrate the complex interactions between metal size, ligand bulk, and molecular structure that exist with these metals. For example, among the alkali metal base-free species, the unsolvated Li derivative crystallizes as a cyclic trimer, whereas the Na salt is found both as a trimer " and as infinite chains of [Na-N(SiMe3)2—] units. The potassium, rubidium, and caesium derivatives exist as discrete dimers in the solid state, constructed around planar [M—N-]2 frameworks. 

Figure 27 The structure of the tetrameric mono(trimethylsilyl)amido complex, [CsHN(SiMe3)2]4-...

Functionalized tertiary aryl phosphines play an important role in transition metal coordination chemistry. These compounds have been used as ligands in synthesis, catalysis, mechanistic studies, and in the study of coordination compounds as structural models. In this contribution the syntheses of two new types of these ligands, tertiary aryl phosphines functionalized by an amide group, are detailed. The published coordination chemistry of these compounds includes the study of intramolecular N—H oxidative addition, the synthesis of chelates stabilized amido complexes, and the preparation of complexes with both ftve- and six-membered chelate rings. ... 

---