A new twist: Structural twisting by about 32° between the semiquinoneiminecopper(II) entities in 2 caused by weak Cu–S interaction results in a different spin arrangement (↑,↓,↑) than for planar 1 (↑,↑,↓). Most revealingly, 2 has an EPR spectrum typical for a radical whereas 1 displays a signal for a CuII center. Oxidation state distributions for the 22+,+,0,−,2− forms are assigned on the basis of UV/Vis/NIR spectroelectrochemistry.

In the last decade a major theme of organometallic chemistry has been the design and development of alternative ligand systems capable of stabilizing monomeric metal complexes while provoking novel reactivity. Exploration of this field is driven by the potential use of these complexes in catalysis and organic synthesis. Examples of monoanionic chelating Ndonor ligands that have received much recent attention (Scheme 1) include the b-diketiminate (I) [1] and the amidinate (II) [2] ligand systems. Much less attention has been given to the closely related triazenides (III). [3, 4] This may be attributed to the lack of suitable ligands that are sterically crowded enough to prevent undesirable ligand redistribution reactions and allow better control of the electronic and steric properties at the metal center.Triazenides are weaker donors than the isoelectronic amidinates and the related b-diketiminates, and should induce greater electrophilicity at a bonded metal atom. [5] This is reflected by the results of an NBO (natural bond orbitals) analysis of the energy-minimized structures [6] of the model anions 1,3-diphenyl-1,3-diketiminate (I M ), 1,3-diphenyl-1,3-diazaallyl (II M ), and 1,3-diphenyltriazenide (III M ) (see Supporting Information), which shows an NPA (natural population analysis) charge for the chelating N atoms of À0.54, À0.60, and À0.38, respectively.We recently succeeded in the preparation of aryl-substituted, sterically crowded triazenes. Ligands of this type may be synthesized in excellent yields by the reaction of different substituted 2-lithiobiphenyls with the m-terphenyl azide 1, followed by hydrolysis (Scheme 2).In a first attempt to test their properties, we have used the obtained triazenes to stabilize pentafluorophenyl compounds of the heavier alkaline-earth metals calcium, strontium, and barium. The heteroleptic pentafluorophenyl triazenides are accessible in tetrahydrofuran as solvent by a convenient onepot transmetalation/deprotonation [7] reaction from the triazene 2 a (HN 3 ArAr'), bis(pentafluorophenyl)mercury, and the corresponding alkaline-earth metal (Scheme 3). After crystallization from n-heptane, either the THF-free compounds [M(C 6 F 5 )(N 3 ArAr')] (M = Sr (4), Ba (5)) or the solvate [Ca(C 6 F 5 )(N 3 ArAr')(thf)] (3) were isolated in good yields. It is remarkable that attempts to replace the pentafluorophenyl substituents by a second triazenide ligand have not been successful so far. Apparently, the steric bulk of the latter prevents further substitution or ligand redistribution and therefore formation of the homoleptic complexes. [8] Solutions of 4 or 5 in aromatic or aliphatic solvents show considerable thermal stability and can be stored at ambient

Thermodynamically stable, but kinetically labile: Trigonal‐prismatic M3L2 metallocages occur in [BF4⊂{Ag3(MsTBim)2}](BF4)2 (1) and [{CuI3⊂[Cu3(MsTBim)2]}2](Cu2I4) (2), the latter with an unprecedented metal‐complex‐host/metal‐complex‐guest arrangement. Large anions such as CF3SO3− or BPh4− have to reside outside the cage facing its “windows”. MsTBim=1,3,5‐tris(benzimidazol‐1‐ylmethyl)‐2,4,6‐trimethylbenzene.

No abstract

The diarylplumbylene R 2 Pb: (3), R ) 2-tBu-4,5,6-Me 3 C 6 H, and the rearranged alkylarylplumbylene RR′Pb:, R ) 2,4,6-tBu 3 C 6 H 2 , R′ ) CH 2 C(CH 3 ) 2 -3,5-tBu 2 C 6 H 3 , were synthesized and characterized by NMR and UV/vis spectroscopy, as well as by X-ray crystallography. Treatment of 3 with the disilylplumbylene R′′ 2 Pb:, R′′ ) Si(SiMe 3 ) 3 , furnished the heteroleptic plumbylene RR′′Pb: (8), which, in the solid state, forms the plumbylene dimer RR′′PbPbRR′′ (9). The X-ray structure analysis of 9 reveals a trans-bent angle of 46.5°and a Pb ... Pb separation of 3.37 Å, the shortest observed so far between the lead atoms of two plumbylenes.

Bis[2-(dimethylamino)ethyl] diselenide was prepared by the reaction of Na 2 Se 2 with ClCH 2 CH 2 NMe 2 . 2-(Dimethylamino)ethaneselenolate complexes of palladium() of the type [PdCl(SeCH 2 CH 2 NMe 2) 2 ] 4 have been synthesized and characterized by elemental analysis, IR and NMR ( 1 H, 31 P, 77 Se) spectroscopy. The structures of orange 1 and of violet (λ max = 514 nm) 2c have been established by single crystal X-ray diffraction analyses. The trimer 1 contains a six-membered Pd 3 Se 3 ring in twist conformation. The thermal behaviour of three complexes, yielding Pd 17 Se 15 has been investigated.

Using density functional theory, we determine parameters of tight-binding Hamiltonians for a variety of Fabre charge transfer salts, focusing, in particular, on the effects of temperature and pressure. Besides relying on previously published crystal structures, we experimentally determine two new sets of structures: (TMTTF) 2 SbF 6 at different temperatures and (TMTTF) 2 PF 6 under various hydrostatic pressures. We find that a few trends in the electronic behavior can be connected to the complex phase diagram shown by these materials. Decreasing temperature and increasing pressure cause the systems to become more two dimensional. We analyze the importance of correlations by considering an extended Hubbard model parameterized using Wannier orbital overlaps and show that while charge order is strongly activated by the intersite Coulomb interaction, the magnetic order is only weakly enhanced. Both orders are suppressed when the effective pressure is increased.

Bei der Oxidation von Samarium mit Schwefel in Gegenwart von SmCl3 und NaN3 als Stickstoff‐Quelle (molares Verhältnis: 12:9:4:2, evakuierte Quarzglasampulle, etwas NaCl als Flußmittel, 850°C, 7 d) fällt Sm4N2S3 in Form von stäbchenförmigen, dunkelroten Einkristallen an. Die Nebenprodukte (NaCl und NaSm2Cl6) werden mit Wasser aus dem Rohprodukt herausgelöst. In der Kristallstruktur von Sm4N2S3 (monoklin, C2/m (Nr. 12), Z = 2, a = 1 318,04(12); b = 391,57(2); c = 1 031,76(9) pm; β = 130,874(6)°; R = 0,036; Rw = 0,031) liegen zwei kristallographisch unterschiedliche Sm3+ in jeweils sechsfacher Koordination der Anionen vor. Neben verzerrten Oktaedern [(Sm1)N3S3] und [(Sm2)NS5] bilden Tetraeder [(N3−)(Sm3+)4], über zwei cis‐ständige Kanten zu Ketten  ∞1[(Sm1)3/3(Sm2)1/1]3+ verknüpft, das strukturelle Hauptmerkmal. Nach Art einer dichtesten „Stabpackung”︁ gebündelt, werden letztere durch zwei kristallographisch unterschiedliche S2− zusammengehalten, die für den Ladungsausgleich und die drei‐dimensionale Vernetzung sorgen.