Reducing hexaazatrinaphthylene (HAN) with potassium in the presence of 18-c-6 produces [{K(18-c-6)}HAN], which contains the S=1/2 radical [HAN]^.−. The [HAN]^.− radical can be transferred to the cobalt(II) amide [Co{N(SiMe₃)₂}₂], forming [K(18-c-6)][(HAN){Co(N′′)₂}₃]; magnetic measurements on this compound reveal an S=4 spin system with strong cobalt–ligand antiferromagnetic exchange and J≈−290 cm⁻¹ (−2 J formalism). In contrast, the Co^II centres in the unreduced analogue [(HAN){Co(N′′)₂}₃] are weakly coupled (J≈−4.4 cm⁻¹). The finding that [HAN]^.− can be synthesized as a stable salt and transferred to cobalt introduces potential new routes to magnetic materials based on strongly coupled, triangular HAN building blocks.

In the presence of stoichiometric or catalytic amounts of [M{N(SiMe₃)₂}₂] (M=Fe, Co), N-heterocyclic carbenes (NHCs) react with primary phosphines to give a series of carbene phosphinidenes of the type (NHC)⋅PAr. The formation of (IMe₄)⋅PMes (Mes=mesityl) is also catalyzed by the phosphinidene-bridged complex [(IMe₄)₂Fe(μ-PMes)]₂, which provides evidence for metal-catalyzed phosphinidene transfer.

Reducing hexaazatrinaphthylene (HAN) with potassium in the presence of 18-c-6 produces [{K(18-c-6)}HAN], which contains the S=1/2 radical [HAN]^.−. The [HAN]^.− radical can be transferred to the cobalt(II) amide [Co{N(SiMe₃)₂}₂], forming [K(18-c-6)][(HAN){Co(N′′)₂}₃]; magnetic measurements on this compound reveal an S=4 spin system with strong cobalt–ligand antiferromagnetic exchange and J≈−290 cm⁻¹ (−2 J formalism). In contrast, the Co^II centres in the unreduced analogue [(HAN){Co(N′′)₂}₃] are weakly coupled (J≈−4.4 cm⁻¹). The finding that [HAN]^.− can be synthesized as a stable salt and transferred to cobalt introduces potential new routes to magnetic materials based on strongly coupled, triangular HAN building blocks.

In the presence of stoichiometric or catalytic amounts of [M{N(SiMe₃)₂}₂] (M=Fe, Co), N-heterocyclic carbenes (NHCs) react with primary phosphines to give a series of carbene phosphinidenes of the type (NHC)⋅PAr. The formation of (IMe₄)⋅PMes (Mes=mesityl) is also catalyzed by the phosphinidene-bridged complex [(IMe₄)₂Fe(μ-PMes)]₂, which provides evidence for metal-catalyzed phosphinidene transfer.

Deprotonation of the yttrium–arsine complex [Cp′₃Y{As(H)₂Mes}] (1) (Cp′=η⁵-C₅H₄Me, Mes=mesityl) by nBuLi produces the μ-arsenide complex [{Cp′₂Y[μ-As(H)Mes]}₃] (2). Deprotonation of the AsH bonds in 2 by nBuLi produces [Li(thf)₄]₂[{Cp′₂Y(μ₃-AsMes)}₃Li], [Li(thf)₄]₂[3], in which the dianion 3 contains the first example of an arsinidene ligand in rare-earth metal chemistry. The molecular structures of the arsine, arsenide, and arsinidene complexes are described, and the yttrium–arsenic bonding is analyzed by density functional theory.

Deprotonation of the yttrium–arsine complex [Cp′₃Y{As(H)₂Mes}] (1) (Cp′=η⁵-C₅H₄Me, Mes=mesityl) by nBuLi produces the μ-arsenide complex [{Cp′₂Y[μ-As(H)Mes]}₃] (2). Deprotonation of the AsH bonds in 2 by nBuLi produces [Li(thf)₄]₂[{Cp′₂Y(μ₃-AsMes)}₃Li], [Li(thf)₄]₂[3], in which the dianion 3 contains the first example of an arsinidene ligand in rare-earth metal chemistry. The molecular structures of the arsine, arsenide, and arsinidene complexes are described, and the yttrium–arsenic bonding is analyzed by density functional theory.

Dimetallic ate complexes were synthesized from the divalent transition metal silylamide complexes {Fe[N(SiMe₃)₂]₂}₂, Cr[N(SiMe₃)₂]₂(thf), Co[N(SiMe₃)₂]₂(thf)₂, and {Mn[N(SiHMe₂)₂]₂}₂ (thf = tetrahydrofuran) by the addition of the corresponding lithium or sodium silylamide salt. Accordingly, donor-free LiFe[N(SiMe₃)₂]₃ and NaMn[N(SiHMe₂)₂]₃ as well as thf-coordinated (thf)NaCr[N(SiMe₃)₂]₃ and (thf)NaCo[N(SiMe₃)₂]₃ were obtained. The thf-containing mixed iron(II)/lithium bis(trimethylsilyl)amide complex (thf)LiFe[N(SiMe₃)₂]₃ was synthesized by the simple addition of thf to the donor-free complex LiFe[N(SiMe₃)₂]₃. All of the complexes were characterized by IR spectroscopy and elemental analysis, and the effective magnetic moments in solution were determined by the Evans method. The solid-state structures of these bis(trimethylsilyl)amido-derived complexes were additionally determined by X-ray crystallography.

The structures of alkali metal complexes of silyl-substituted ansa-tris(allyl) ligands [RSi(C₃H₃SiMe₃)₃]^3– (R = Me, L¹; or Ph, L²) are discussed. Triple deprotonation of L¹H₃ by nBuNa/tmeda affords [L¹{Na(tmeda)}₃] (4) in which the sodium cations are complexed by ηⁿ-allyl ligands and the silyl substituents adopt [exo,exo][endo,exo]₂ stereochemistries in one crystallographically disordered form and [endo,exo]₃ in another. Triple deprotonation of L²H₃ with nBuLi/tmeda results in the formation of [L²{Li(tmeda)}₃] (5), the structure of which features silyl substituents with [exo,exo]₂[endo,exo] stereochemistries. The trisodium complex [L²Na{Na(tmeda)}₂]₂ (6) consists of a hexa(allylsodium) macrocycle that aggregates as a result of cation–π interactions between the phenyl substituents and the sodium cations. An attempt to prepare the tripotassium complex of L¹ resulted in the formation of the bimetallic potassium/lithium complex [L²{K(OEt₂)₂}₂KLi(μ₄-OtBu)]₂ (7), in which the lithium tert-butoxide by-product is incorporated into a hexa(allylpotassium) macrocycle. Triple deprotonation of L¹H₃ with nBuLi and the terdentate Lewis base pmdeta results in [L¹Li(pmdeta)}₃] (8), in which the three allyl groups do not μ-bridge between lithium cations, resulting in an [exo,exo]₃ stereochemistry of the silyl substituents. NMR spectroscopic studies reveal complicated solution-phase behaviour for 4, 6 and 7, whereas the solid-state structures of 5 and 8 are preserved in solution. Further insight into the structures andstereochemical preference of the ansa-tris(allyl) ligands in 4 and 5 is provided by detailed density functional theory calculations.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)