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Three extremely bulky 1,3,5-triazapentadienes, [sup.Ar]NNNH ([sup.Ar]NNN=N[{C([Bu.sup.t])=N(Ar)}.sub.2]; Ar=Mes (mesityl), Dep (2,6-diethylphenyl), or Dip (2,6-diisopropylphenyl)) have been prepared and structurally characterized. These are readily deprotonated, yielding a series of lithium and potassium triazapentadienyl complexes, one of which, ([sup.Dip]NNN)Li, has been structurally characterized. Similarly, three monomeric triazapentadienyl magnesium iodide complexes, ([sup.Ar]NNN)MgI(O[Et.sub.2]), and a dimeric calcium counterpart, [{([sup.Mes]NNN)Ca(THF)([mu]-I)}.sub.2], have been prepared. Attempts to reduce the former gave homoleptic bis(triazapentadienyl) magnesium complexes, [([sup.Ar]NNN).sub.2]Mg (Ar = Mes or Dep) as the main products. One reaction also gave a very low yield of the magnesium(I) dimer, [{([sup.Dep]NNN)Mg-}.sub.2], which was structurally characterized. In related chemistry, two triazapentadienyl boron difluoride compounds, ([sup.Ar]NNN)B[F.sup.2] (Ar = Mes or Dep), have been synthesized, and unsuccessful attempts have been made to reduce these to boron(I) heterocycles. For sake of comparison, attempts have been made to prepare a series of related amino-substituted [beta]-diketiminato group 13 element(I) heterocycles. Although these were also not successful, several group 13 element(III) halide complexes incorporating this ligand class have been characterized. Key words: triazapentadienyl, steric bulk, [beta]-diketiminate, group 2, group 13, magnesium(I). Nous avons synthétisé trois 1,3,5-triazapentadiènes extrêmement encombrés de formule [sup.Ar]NNNH [[sup.Ar]NNN = N[{C([Bu.sup.t])= N(Ar)}.sub.2]; Ar = Mes (mésityl), Dep (2,6-diéthylphényl) ou Dip (2,6-diisopropylphényl)] et les avons caractérisés du point de vue structural. Ces composés sont facilement déprotonés, formantune série de complexes de type triazapentadiényle avec le lithium et le potassium. La caractérisation de l'un d'entre eux, le ([sup.Dip]NNN)Li, a permis d'en révéler la structure. De manière similaire, nous avons préparé trois complexes monomériques d'iodure de magnésium de type triazapentadiényl, de formule ([sup.Ar]NNN)MgI(O[Et.sub.2]), et un analogue dimérique complexé avec le calcium, le [{([sup.Mes]NNN)Ca(THF)([mu]-I)}.sub.2]. En tentant de réduire ces trois premiers complexes, nous avons obtenu les complexes homoleptiques de type bis(triazapentadiényl)magnésium de formule [([sup.Ar]NNN).sub.2]Mg (Ar = Mes ou Dep) comme produits majoritaires. Dans une réaction, nous avons également obtenu un très faible rendement du dimère de magnésium(I) [{([sup.Dep]NNN)Mg-}.sub.2], que nous avons caractérisé pour en confirmer la structure. En employant une approche similaire, nous avons synthétisé deux composés de type difluorure de triazapentadiénylbore, de formule ([sup.Ar]NNN)B[F.sup.2] (Ar = Mes ou Dep), et notre tentative de réduire ces hétérocycles de bore(I) s'est révélée infructueuse. À titre de comparaison, nous avons tenté de préparer une série d'hétérocycles dérivés de type [beta]-dicétiminate portant des substituants amines, complexés avec des éléments(I) du groupe 13. Bien que ces dernières tentatives aient également été sans succès, nous avons caractérisé plusieurs complexes d'halogénures d'éléments(III) du groupe 13 portant des ligands de cette classe. [Traduit par la Rédaction] Mots-clés: triazapentadiényl, encombrement stérique, [beta]-dicétiminate, groupe 2, groupe 13, magnésium(I)., Introduction The fundamental and applied chemistry of compounds containing main group elements in very low oxidation states and (or) with very low coordination numbers has rapidly expanded in recent decades. [...]

The potassium salt of an extremely bulky β-diketiminate, [K(Ar*Nacnac)] (Ar*Nacnac, [(Ar*NCMe)2CH]−; Ar*, C6H2Me{C(H)Ph2}2-4,2,6) was reacted with either CaI2 or YbI2(THF)2, which afforded [(Ar*Nacnac)MI] (M = Ca or Yb). These are the first examples of structurally characterised, donor solvent-free, N-arene substituted β-diketiminato calcium and ytterbium complexes that incorporate a terminal iodide ligand. Reduction of [(Ar*Nacnac)CaI] with sodium metal gave a complex product mixture, from which a few crystals of the β-diketiminate C–H activated product, [{Ca(μ-Ar*Nacnac-H)}2], were obtained and crystallographically characterised. In an attempt to form a terminal ytterbium hydride compound, treatment of [(Ar*Nacnac)YbI] with K[HBEt3] gave a good yield of the contact ion pair compound [(Ar*Nacnac)Yb(HBEt3)]. The extremely bulky β-diketiminato calcium(ii) and ytterbium(ii) iodide complexes [(Ar*Nacnac)MI] (M = Ca or Yb) have been prepared. The reduction of [(Ar*Nacnac)CaI] with sodium metal yielded a ligand C–H activated product, while reaction of [(Ar*Nacnac)YbI] with K[HBEt3] gave an ytterbium(ii) borate contact ion pair (e.g. see picture). [ABSTRACT FROM AUTHOR]

The potassium salt of an extremely bulky β-diketiminate, [K(Ar*Nacnac)] (Ar*Nacnac, [(Ar*NCMe)2CH]−; Ar*, C6H2Me{C(H)Ph2}2-4,2,6) was reacted with either CaI2 or YbI2(THF)2, which afforded [(Ar*Nacnac)MI] (M = Ca or Yb). These are the first examples of structurally characterised, donor solvent-free, N-arene substituted β-diketiminato calcium and ytterbium complexes that incorporate a terminal iodide ligand. Reduction of [(Ar*Nacnac)CaI] with sodium metal gave a complex product mixture, from which a few crystals of the β-diketiminate C–H activated product, [{Ca(μ-Ar*Nacnac-H)}2], were obtained and crystallographically characterised. In an attempt to form a terminal ytterbium hydride compound, treatment of [(Ar*Nacnac)YbI] with K[HBEt3] gave a good yield of the contact ion pair compound [(Ar*Nacnac)Yb(HBEt3)]. The extremely bulky β-diketiminato calcium(ii) and ytterbium(ii) iodide complexes [(Ar*Nacnac)MI] (M = Ca or Yb) have been prepared. The reduction of [(Ar*Nacnac)CaI] with sodium metal yielded a ligand C–H activated product, while reaction of [(Ar*Nacnac)YbI] with K[HBEt3] gave an ytterbium(ii) borate contact ion pair (e.g. see picture). [ABSTRACT FROM AUTHOR]

Reaction of Ba[N(SiMe 3 ) 2 ] 2 with PhSiH 3 in toluene gave simple access to the unique Ba hydride cluster Ba 7 H 7 [N(SiMe 3 ) 2 ] 7 that can be described as a square pyramid spanned by five Ba 2+ ions with two flanking BaH[N(SiMe 3 ) 2 ] units. This heptanuclear cluster is well soluble in aromatic solvents, and the hydride 1 H NMR signals and coupling pattern suggests that the structure is stable in solution. At 95 °C, no coalescence of hydride signals is observed but the cluster slowly decomposes to undefined barium hydride species. The complex Ba 7 H 7 [N(SiMe 3 ) 2 ] 7 is a very strong reducing agent that already at room temperature reacts with Me 3 SiCH=CH 2 , norbornadiene, and ethylene. The highly reactive alkyl barium intermediates cannot be observed and deprotonate the (Me 3 Si) 2 N - ion, as confirmed by the crystal structure of Ba 14 H 12 [N(SiMe 3 ) 2 ] 12 [(Me 3 Si)(Me 2 SiCH 2 )N] 4 ., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The first examples of magnesium acyls, [(Nacnac)Mg{μ-C(Ph)O}(μ-OR)Mg(Nacnac)] (R=Me, tBu or Ph; Nacnac=[HC(MeCNAr) 2 ] - ; Ar=C 6 H 2 Me 3 -2,4,6 ( Mes Nacnac), C 6 H 3 Et 2 -2,6 ( Dep Nacnac), C 6 H 3 iPr 2 -2,6 ( Dip Nacnac)), have been prepared by reductive cleavage of a series of esters using dimeric magnesium(I) reducing agents, [{(Nacnac)Mg} 2 ]. Crystallographic studies reveal the complexes to be dimeric, being bridged by both phenyl-acyl and alkoxide/aryloxide fragments. The crystal structures, combined with results of spectroscopic and computational studies suggest that the nature of the acyl ligands within these complexes should be viewed as lying somewhere between anionic umpolung acyl and oxo-carbene. However, reactions of the acyl complexes with a variety of organic electrophiles did not provide evidence of umpolung acyl reactivity. A number of attempts to prepare alkoxide free magnesium acyls were carried out, and while these were unsuccessful, they did lead to unusual products, the crystallographic and spectroscopic details of which are discussed., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The synthesis of a class of electron-rich amino-functionalized β-diketiminato (N-nacnac) ligands is reported, with two synthetic methodologies having been developed for systems bearing backbone NMe 2 or NEt 2 groups and a range of N-bound aryl substituents. In contrast to their (Nacnac)H counterparts, the structures of the protio-ligands feature the bis(imine) tautomer and a backbone CH 2 group. Direct metalation with lithium, magnesium, or aluminium alkyls allows access to the respective metal complexes through deprotonation of the methylene function; in each case X-ray structures are consistent with a delocalized imino-amide ligand description. Transmetalation using lithium N-nacnac complexes is then exploited to access p- and f-block metal complexes, which allow for like-for-like benchmarking of the N-nacnac ligand family against their more familiar Nacnac counterparts. In the case of Sn II , the degree of electronic perturbation effected by introduction of the backbone NR 2 groups appears to be constrained by the inability of the amino group to achieve effective conjugation with the N 2 C 3 heterocycle. More obvious divergence from established structural norms is observed for complexes of the harder Yb II ion, with azaallyl/imino and even azaallyl/NMe 2 coordination modes being demonstrated by X-ray crystallography., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)