The reaction of benzamidinato silicon trichloride [{PhC(NR)2}SiCl3] [R = Bu(t) (1), SiMe3 (2)] with 2 equiv of potassium in THF afforded mononuclear chlorosilylene [{PhC(NBu(t))2}SiCl] (3) and [{PhC(NSiMe3)2}2SiCl2] (4), respectively. Compound 4 was formed by the disproportionation of unstable [{PhC(NSiMe3)2}SiCl]. The reaction of [{PhC(NBu(t))2}SiCl3] (1) with 1 equiv of LiR (R = NMe2, OBu(t), OPr(i), PPr(i)2) in THF yielded [{PhC(NBu(t))2}SiCl2R] [R = NMe2 (5), OBu(t) (6), OPr(i) (7), PPr(i)2 (8)]. Treatment of 5-8 with 2 equiv of potassium in THF resulted in the novel heteroleptic silylene [{PhC(NBu(t))2}SiR] [R = NMe2 (9), OBu(t) (10), OPr(i) (11), PPr(i)2 (12)]. Compounds 4, 9, and 12 have been analyzed by X-ray crystallography.

The syntheses, spectroscopy and single crystal X-ray structures of the multifunctional acrylamide-derived ligand N-pyrazolylpropanamide (ϭ L) (1), and its complexes [L 2 CuCl 2 ] (2) and [L 4 Co 3 Cl 6 ] (3) with copper(II) and cobalt(II) chlorides, respectively, are described. The ligand 1 is easily obtained in one step by the reaction of pyrazole with acrylamide in a 1:1 molar ratio in the presence of trimethylbenzylammonium hydroxide as a basic catalyst. The reaction of CuCl 2 · 2H 2 O with 1 in a 1:2 metal salt:ligand molar ratio in ethanol/-triethylorthoformate solution gave coordination compound 2. The crystal structure of 2 contains two sevenmembered chelate rings formed by two nitrogen atoms of the pyrazolyl groups and two weakly coordinated carbonyl oxygen atoms Materials. Acrylamide, pyrazole, trimethylbenzylammonium hydroxide (Triton B, 40 % in methanol), copper(II)chloride dihydrate, cobalt(II)chloride hexahydrate, triethylorthoformate (for dehydration), acetonitrile (99 %) and absolute ethanol were all obtained from commercial suppliers and used as received.Physical Methods. Microanalyses of the compounds were performed using a Leco CHNS 923 apparatus. Melting points were

The reaction of base-free Ph 2 Be with 1, in toluene gaVe the carbene adduct Ph 2 Be(i-Pr-carbene) (1) as colorless crystal blocks. For comparison, the di-n-butyl ether adduct Ph 2 -Be(n-Bu 2 O) (2) was prepared from BeCl 2 and PhLi in a mixture of Et 2 O and n-Bu 2 O. Single-crystal X-ray determinations reVeal monomeric solid-state structures for both complexes.

Readily accessible and easy-to-use phenyliodine(III) dichloride, PhICl(2), has been established as an innovative and superior reagent for the one-electron oxidation of cerium(III) complexes, comprising amide, amidinate, and cyclopentadienyl derivatives. Its use allowed the successful synthesis and structural characterization of the first members of three new classes of chloro-functionalized (organo)cerium(IV) compounds, including the long sought-after Cp(3)CeCl.

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The first structurally authenticated linear, homoleptic triple-decker sandwich complex of an f-element, (η8-COT′′)Nd(μ-η8:η8-COT′′)Nd(η8-COT′′) (2; COT′′ = [C8H6(SiMe3)2-1,4]2−) has become available through a rather unexpected synthetic pathway. Treatment of [Li(THF)4][Nd(COT′′)2] (1) with anhydrous cobalt(II) chloride (molar ratio ca. 2:1) in a toluene suspension afforded 2 in 72% isolated yield. The most notable structural feature of 2 is the near-linear arrangement of the COT′′ rings with (ring centroid)−Nd−(ring centroid) angles of 176.1 and 175.6°, respectively, and a Nd−(ring centroid)−Nd angle of 177.9°, making the title compound the first true molecular model for lanthanide-based nanowires.

This paper gives a full account of the complex reaction system LnCl3/(COT″)2– (COT″ = 1,4-bis(trimethylsilyl)cyclooctatetraenyl dianion). Four different series of organolanthanide complexes of this bulky COT ligand have been reported: (1) anionic sandwich complexes containing [Ln(COT″)2]− anions, (2) dimeric chloro-bridged mono(COT″) complexes, (3) cluster-centered multidecker-sandwich complexes, and (4) linear triple-decker sandwich complexes. In order to get a more complete picture of the reaction system LnCl3/(COT″)2– and to examine possible steric effects exerted by the COT″ ligand, four new rare-earth-metal COT″ complexes have been prepared: [Li(DME)3][Ce(COT″)2] (1), [Li(THF)4][Nd(COT″)2] (2), [(COT″)Nd(μ-Cl)(THF)]2 (4), and (COT″)Yb(DIPPForm)(THF) (5,; DIPPForm = [HC(NAr)2]−, Ar = 2,6-diisopropylphenyl). For comparison, the COTTBS derivative [Li(DME)3][Ce(COTTBS)2] (3; COTTBS = 1,4-bis(tert-butyldimethylsilyl)cyclooctatetraenyl dianion) has also been synthesized. It was found that the steric effect of either COT″ or COTTBS on the molecular structures of the anionic sandwich complexes 1–3 with coplanar ring ligands is rather small. In (COT″)Yb(DIPPForm)(THF) (5), the combination of COT″ with a sterically demanding formamidinate ligand in the coordination sphere of Yb3+ still leaves room for THF coordination. For example, in 4, the bulky COT″ leads to coordination of only one THF per Ln in comparison to the parent chloro-bridged dimers [(COT)Ln(μ-Cl)(THF)2]2. However, in the dimeric chloro-bridged mono(COT″) complexes the presence of COT″ reduces the number of coordinated THF molecules. Quite surprisingly, an attempt to prepare the holmium analogue of the known linear triple-decker sandwich complex (COT″)Nd(μ-η8:η8-COT″)Nd(COT″) led to formation of the isomerized triple-decker (COT″)Ho[μ-η8:η8-C8H6(SiMe3)2-1,5]Ho(COT″) (6), as a result of steric pressure-induced silyl group migration. All new complexes 1–6 have been structurally characterized by X-ray diffraction.

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