Philippe G. Merle

Review of metal 1-azaallyl complexes

Abstract This review provides a comprehensive survey relating to the synthesis, characterisation and reactivity of main group and d- and f-block metal 1-azaallyl complexes. Section 1 introduces the topic and defines the scope of the article, Section 2 considers general methods of preparation and Section 3 discusses the diversity of bonding modes of the 1-azaallylmetal complexes. Section 4 provides a group by group account of metal 1-azaallyls. Section 5 describes in outline the chemistry of related complexes, namely 2-pyridylalkylmetal and related metal complexes. Finally, we provide a table summarising data on individual metal 1-azaallyls.

Unusual alkali metal α- or β-phenyl(trimethylsilyl)amides

The synthesis (1–3 and 5) and structures (1–5) of the crystalline, hydrocarbon-soluble metal amides [M{μ-N(SiMe3)(SiMe2Ph)}(NCBut )n]2 [n = 0 and M = Li 1 (cis), M = Na 2 (trans) having intermolecular Na⋯C contacts, or n = 1 and M = Na (cis) 3], [Li{μ-N(SiMe3)Ph}-cis]2[μ- {N(SiMe3)Ph}Li-cis]2 4 and trans-[Na{μ-N(SiMe3)Ph}(tmen)] 5 are reported.

Synthesis and structures of crystalline Li, Al and Sn(II) 1-azaallyls and β-diketiminates derived from [Li{μ,η3-N(SiMe3)C(Ad)C(H)SiMe3}]2 (Ad = 1-adamantyl)

The crystalline dimeric 1-azaallyllithium complex [Li{mu,eta(3-N(SiMe3)C(Ad)C(H)SiMe3}]2 (1) was prepared from equivalent portions of Li[CH(SiMe3)2] and 1-cyanoadamantane (AdCN). Complex was used as precursor to each of the crystalline complexes 2-8 which were obtained in good yield. By 1-azaallyl ligand transfer, 1 afforded (i) [Al{eta3-N(SiMe3)C(Ad)C(H)SiMe3}{kappa1-N(SiMe3)C(Ad)=C(H)SiMe3-E}Me] (5) with [AlCl2Me](2), (ii) [Sn{eta3-N(SiMe3)C(Ad)C(H)SiMe3}2] (7) with Sn[N(SiMe3)2]2, and (iii) [Li(N{C(Ad)=C(H)SiMe3-E}{Si(NN)SiMe3})(thf)2] (8) with the silylene Si[(NCH(2)Bu(t))2C6H(4)-1,2] [= Si(NN)]. By insertion into the C[triple bond, length as m-dash]N bond of the appropriate cyanoarene RCN, gave the beta-diketiminate [Li{mu-N(SiMe3)C(Ad)C(H)C(R)NSiMe3}]2 [R = Ph (2), C(6)H(4)Me-4 (3)], and yielded [Al{kappa2-N(SiMe3)C(Ad)C(H)C(Ph)NSiMe3}{kappa1-N(SiMe3)C(Ad)=C(H)SiMe3-E}Me] (6). The beta-diketiminate [Al{kappa2-N(SiMe3)C(Ad)C(H)C(Ph)NSiMe3}Me2] (4) was prepared from 2 and [AlClMe2]2. The X-ray structures of 1 and 3-8 are presented. Multinuclear NMR spectra in C6D6 or C6D5CD3 have been recorded for each of 1-8; such data on 8 revealed that in solution two minor isomers were also present.

Li, Al, Sn and Zr Complexes of Bidentate N,N′-Centred Ligands

The N,N′-centred ligands [(NSiMe3)2-C6H4-1,2]2− [A]2− and [N(SiMe3)C(C6H4Me-p)N(Ph)]-[B]− were prepared as their dilithium tmeda [Li2A(tmeda)2] or lithium diethyl ether adducts [LiB(Et2O)]2 respectively. The X-ray structure of [LiB(OEt2)]2 is reported; ligand [B]− is C 1-symmetric Both ligand were used in the preparation of Al, Sn(II) and Zr(IV) complexes which were isolated and X-ray characterised. [SnA(tmeda)] 1, [ZrCl2A(tmeda)] 2 and [Al(Me)A] 3 are monomeric in the solid state whereas [(AlMe2)2A]2 4 is dimeric. Compounds [SnB2] 5 and [AlMeB2] 6 are monomeric in the solid state and present a butterfly-like structure.

A comparative study of the behaviour of N-trimethylsilyl and N-neopentyl-anilines and 1,2-diaminobenzenes towards trimethylalane; X-ray structures of nine Al–N compounds

The reactions of a pair each of monosubstituted anilines PhNHR1 and disubstituted 1,2-diaminobenzenes C6H4(NHR1)2-1,2 (R1 = SiMe3 = R, or R1 = CH2But = R′) with 1 or 2 equivalents of trimethylalane have been investigated. The trimethylsilyl derivatives were more reactive than the neopentyl analogues. The following crystalline compounds were obtained at ambient temperature or (1) gentle heating: trans-[AlMe2(μ-NRPh)]21, [AlMe3{NH(R′)Ph}] 2, [(AlMe2)2{μ-(NR)2C6H4-1,2}] 4, [(AlMe2){μ-(NR′)2C6H4-1,2}] 5, [(AlMe){N(R)C6H4NR-μ-1,2}]26 and [AlMe2{N(R′(C6H4N(H)R′}] 7, while prolonged heating was required in order to obtain [AlMe2(μ-NR′Ph)]23 and [(AlMe{N(R′)C6H4NR′-μ-1,2}]28. The amine adducts 2 and 7, were identified as intermediates to 3 and 8, respectively. Treatment of C6H4(NHR′)2-1,2 with successively 2 LiBun and 2 AlCl3 afforded [AlCl{N(R′)C6H4NR′-µ-1,2}]29. The diamine adduct [C6H4{N(H)R′(AlMe3)}2-1,3] 10 was obtained from C6H4(NHR′)2-1,3 and 2 AlMe3; while the same diamine with successively 2 LiBun, 2 AlClMe2 and 2 tmen yielded a compound tentatively formulated as [C6H4{N(R′)AlMe2(tmen)}2-1,3] 11. The X-ray structures of 1–7, 9 and 10 are presented.