A series of symmetrical and unsymmetrical N,N′-disubstituted aminotroponimines (ATIHs) have been prepared. Substituents ranging from linear to cyclic alkyl groups, chelating ethers, and aryl groups were employed. The corresponding aminotroponiminate zinc complexes were then synthesized and characterized by a number of techniques, including by X-ray crystallography. Herein we report on the investigations into their activity in the intramolecular hydroamination of nonactivated alkenes. We also demonstrate that complexes bearing ligands with cyclic alkyl groups show superior activity in a number of selected reactions with functionalized aminoalkenes.

A series of yttrium and lanthanide amido complexes [Ln{N(SiHMe₂)₂}₂{CH(PPh₂NSiMe₃)₂}] (Ln=Y, La, Sm, Ho, Lu) were synthesized by three different pathways. The title compounds can be obtained either from [Ln{N(SiHMe₂)₂}₃(thf)₂] and [CH₂(PPh₂NSiMe₃)₂] or from KN(SiHMe₂)₂ and [Ln{CH(PPh₂NSiMe₃)₂}Cl₂]₂, while in a third approach the lanthanum compound was synthesized in a one-pot reaction starting from K{CH(PPh₂NSiMe₃)₂}, LaCl₃, and KN(SiHMe₂)₂. All the complexes have been characterized by single-crystal X-ray diffraction. The new complexes, [Ln{N(SiHMe₂)₂}₂{CH(PPh₂NSiMe₃)₂}], were used as catalysts for hydroamination/cyclization and hydrosilylation reactions. A clear dependence of the reaction rate on the ionic radius of the center metal was observed, showing the lanthanum compound to be the most active one in both reactions. Furthermore, a combination of both reactions—a sequential hydroamination/hydrosilylation reaction—was also investigated.

The reaction of the bis(amino)cyclodiphosph(III)azane, cis-{(tBuNH)₂(PNtBu)₂}, with AlMe₃, AlClMe₂, AlCl₂Me, and AlCl₃ is reported. The less Lewis acidic compound AlMe₃ forms the adduct cis-[(tBuNH)₂(PNtBu){P(⋅AlMe₃)NtBu}] (1), in which the aluminum atom is exclusively coordinated to one phosphorus atom. At elevated temperatures AlMe₃ undergoes migratory exchange between the two phosphorus atoms, but no methane elimination is observed. By using the more Lewis acidic compound AlClMe₂ the P-coordinated compound cis-[(tBuNH)₂(PNtBu){P(⋅AlClMe₂)NtBu}] (2) can be obtained at low temperatures. Compound 2 rearranges irreversibly to a product in which the AlClMe₂ group is coordinated by one exo-cyclic nitrogen atom. A concomitant 1,2-H shift from this nitrogen atom onto the phosphorus atom is observed. The N-coordinated rearrangement product slowly decomposes via a PN bond cleavage in solution. Reaction of the even more Lewis acidic compounds AlCl₂Me and AlCl₃ finally led to stable adducts, cis-[(tBuNH)(PNtBu)(tBuN⋅AlCl₂Me){P(H)NtBu}] (3), and cis-[(tBuNH)(PNtBu)(tBuN⋅AlCl₃){P(H)NtBu}] (4), in which the aluminum atoms are N-coordinated by a tBuNPH unit.

Gegensätze ziehen sich an: [(η⁵-C₅Me₅)₂LnAl(η⁵-C₅Me₅)] (Ln=Eu, Yb; siehe Abbildung) sind die ersten Verbindungen mit einer Bindung zwischen Aluminium und einem 4f-Metall. Die Bindung setzt sich vorwiegend aus elektrostatischen Anteilen zusammen; Beiträge aus Ladungstransfer und kovalenten Anteilen fallen nur gering aus.

Opposites attract: The compounds [(η⁵-C₅Me₅)₂LnAl(η⁵-C₅Me₅)] (Ln=Eu, Yb; see scheme) represent the first compounds with a bond between aluminum and a 4f metal. The bonds are predominantly electrostatic with insignificant charge-transfer and covalent contributions.

Yttrium and lanthanide complexes with different P,N ligands in the coordination sphere have been synthesized. First the chloride complexes [{CH(PPh₂NSiMe₃)₂}Ln{(Ph₂P)₂N}Cl] (Ln=Y (1 a), La (1 b), Nd (1 c), Yb (1 d)) having the bulky [CH(PPh₂NSiMe₃)₂]⁻ and the flexible [(Ph₂P)₂N]⁻ ligands in the same molecule were prepared by three different synthetic pathways. Compounds 1 a–d can be obtained by reaction of [{[CH(PPh₂NSiMe₃)₂]LnCl₂}₂] with [K(thf)_nN(PPh₂)₂] (n=1.25, 1.5) or by treatment of [{(Ph₂P)₂N}LnCl₂(thf)₃] with K[CH(PPh₂NSiMe₃)₂]. Furthermore, a one-pot reaction of K[CH(PPh₂NSiMe₃)₂] with LnCl₃ and [K(thf)_nN(PPh₂)₂] leads to the same products. Single-crystal X-ray structures of 1 a–d show that the conformation of the six-membered metallacycle (N1-P1-C1-P2-N2-Ln) which is formed by chelation of the [CH(PPh₂NSiMe₃)₂]⁻ ligand to the lanthanide atom is influenced by the ionic radius of the central metal atom. In solution dynamic behavior of the [(Ph₂P)₂N]⁻ ligand is observed, which is caused by rapid exchange of the two different phosphorus atoms. Further reaction of 1 b with KNPh₂ resulted in [{(Me₃SiNPPh₂)₂CH}La{N(PPh₂)₂}(NPh₂)] (2). Compounds 1 a–d and 2 are active in the ring-opening polymerization of ε-caprolactone and the polymerization of methyl methacrylate. In some cases high molecular weight polymers with good conversions and narrow polydispersities were obtained. In both polymerizations the catalytic activity depends on the ionic radius of the metal center.

Einfach und vielseitig: Ein neuer Zink-Komplex katalysiert die intramolekulare Hydroaminierung von nichtaktivierten Olefinen und Alkinen (siehe Beispiel im Schema; {(iPr)₂ATI}=N-Isopropyl-2-(isopropylamino)troponiminato). Der Katalysator ist relativ stabil, zeigt ausgezeichnete Aktivitäten und toleriert Ether-, Thioether- und Amid-Funktionen.

Treatment of the recently reported potassium salt [K(thf)_n][N(PPh₂)₂] (n=1.25, 1.5) with anhydrous yttrium or lanthanide trichlorides in THF leads after crystallization from THF/n-pentane (1:2) to the monosubstituted diphosphanylamide complexes [LnCl₂{(Ph₂P)₂N}(thf)₃] (Ln=Y, Sm, Er, Yb). The single-crystal X-ray structures of these complexes show that the metal atoms are surrounded by seven ligands in a distorted pentagonal bipyramidal arrangement, in which the chlorine atoms are located in the apical positions. The diphosphanylamide ligand is always η²-coordinated through the nitrogen atom and one phosphorus atom. Further reaction of [SmCl₂{(Ph₂P)₂N}(thf)₃] with K₂C₈H₈ or reaction of [LnI(η⁸-C₈H₈)(thf)₃] with [K(thf)_n][N(PPh₂)₂] in THF gives the corresponding cyclooctatetraene complexes [Ln{(Ph₂P)₂N}(η⁸-C₈H₈)(thf)₂] (Ln=La, Sm). The single crystals of these compounds contain enantiomerically pure complexes. Both compounds adopt a four-legged piano-stool conformation in the solid state. The structures of the A and the C enantiomers were established by single-crystal X-ray diffraction. The more soluble bistrimethylsilyl cyclooctatetraene complex [Y{(Ph₂P)₂N}(η⁸-1,4-(Me₃Si)₂C₈H₆)(thf)₂] was obtained by transmetallation of Li₂[1,4-(Me₃Si)₂C₈H₆] with anhydrous yttrium trichloride in THF followed by the addition of one equivalent of [K(thf)_n][N(PPh₂)₂]. The ⁸⁹Y NMR signal of the complex is split up into a triplet, supporting other observations that the phosphorus atoms are chemically equivalent in solution and, thus, dynamic behavior of the ligand in solution can be anticipated.

Katalytisch zu chiralen Aminen: Die enantioselektive katalytische Hydroaminierung (siehe Schema) ist eine der großen Herausforderungen der synthetischen Organischen und Metallorganischen Chemie und eröffnet einen attraktiven Zugang zu chiralen Aminen. Neueste Beispiele dieser Reaktion werden vorgestellt.

Catalytically to chirality: Enantioselective catalytic hydroamination (see scheme) is one of the major challenges in synthetic organic and organometallic chemistry and offers a very attractive synthetic pathway to chiral amines. Recent progress made with this reaction is presented.

The coordination chemistry of inorganic amides in Group 3 and lanthanide chemistry is discussed. Three different ligand systems (phosphino-amides, bis(phosphino)amides, and bis(phosphinimino)methanides) that consist of one or more PN units were used. In this series the steric demand of the ligands is increased in a stepwise fashion and the negative charge is delocalized over more atoms. These properties were used in the design of new lanthanide complexes. For all three compounds the synthesis of the alkali metal derivatives is reported first, followed by the reaction of the alkali metal salts with various lanthanide trichlorides. Further reactions of the obtained lanthanide complexes as well as their application as catalysts are discussed. Most of the reported complexes show a dynamic behavior in solution. In phosphinoamide and bis(phosphino)amide complexes, in which the phosphorus atom is in oxidation state +3, there is always a weak coordination of the phosphorus atom to the lanthanide atom observed. In bis(phosphinimino)methanide complexes, in which the phosphorus atom is in oxidation state +5, no such interaction is noticeable. Instead a weak coordination of the methine atom to the center metal can be seen in the solid state. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:514–520, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10096

Treatment of the bis(phosphanyl)amide (Ph₂P)₂NH with KH in boiling THF followed by crystallization from THF/n-pentane leads to [K(thf)_n][N(PPh₂)₂] (n=1.25, 1.5). Reaction of [K(thf)_n][N(PPh₂)₂] with anhydrous yttrium or lanthanide trichlorides in a 3:1 molar ratio afforded homoleptic bis(phosphanyl)amide complexes [Ln{N(PPh₂)₂}₃] (Ln=Y, Er) as large crystals in good yields. [Ln{N(PPh₂)₂}₃] can also be obtained by reaction of the homoleptic bis(trimethylsilyl)amides of Group 3 metals and lanthanides [Ln{N(SiMe₃)₂}₃] (Ln=Y, La, Nd) with three equivalents of (Ph₂P)₂NH in boiling toluene. The single-crystal X-ray structures of these complexes always show η² coordination of the ligand. Dynamic behavior of the ligand is observed in solution and is caused by rapid exchange of the two different phosphorus atoms. [Ln{N(PPh₂)₂}₃] was used as catalyst for the polymerization of ε-caprolactone. Significant differences in terms of correlation of theoretical and experimental molecular weights as well as polydispersities were observed depending on the nature of Ln. On the basis of the crystal structure of the heteroleptic complex [Lu{N(PPh₂)₂}₃(thf)], we suggest that in the initiation step of ε-caprolactone polymerization the lactone adds to the lanthanide atom to form a sevenfold coordination sphere around the central atom.