Synthesis and X-ray crystal structure of [1,3-bis(η5-cyclopentadienyl)-1,1,3,3-tetramethyldisiloxane]hafnium(IV) dichloride

Summary The tetramethyldisiloxane-bridged hafnocene complex [HfCl₂{-(⁵-C₅H₄)SiMe₂OSiMe₂(²-C₅H₄)}] (1) has been prepared by the reaction of HfCl₄ with the dilithiatedbis(cyclopentadienyl)disiloxane (LiC₅H₄SiMe₂)₂O in a molar ratio of 1:2. The new compound was characterized by spectroscopic and X-ray diffraction methods. The crystals are monoclinic of space groupP2₁/c and isostructural with the corresponding complexes of titanium and zirconium. The unit cell dimensions area=13.51(1) Å,b=8.672(7) Å,c=15.41(1) Å, =97.15(2)°, andZ=4.

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Darstellung und Röntgenkristallstruktur von [1,3-Bis(⁵-cyclopentadienyl)-1,1,3,3-tetramethyldisiloxan]hafnium(IV)dichlorid

Zusammenfassung Der tetramethyldisiloxan-überbrückte Hafnocenkomplex [HfCl₂{-(⁵-C₅H₄)-SiMe₂OSiMe₂(²-C₅H₄)}] (1) wurde durch Umsetzung von HfCl₄ mit dem lithiiertenBis(cyclopentadienyl)disiloxan (LiC₅H₄SiMe₂)₂O im Molverhältnis 1:2 dargestellt. Die neue Verbindung wurde spektroskopisch und röntgenographisch charakterisiert. Sie kristallisiert in der monoklinen RaumgruppeP2₁/c und ist isostrukturell mit den entsprechenden Titan-und Zirkoniumkomplexen. Die Dimensionen der Einheitszelle sinda=13.51(1) Å,b=8.672(7) Å,c=15.41(1) Å, =97.15(2)° undZ=4.

     

Cyano Derivatives of Bis(cyclopentadienyl)titanium(IV). The crystal and molecular structure of μ-Oxo-bis[bis(cyclopentadienyl)cyanotitanium(IV)], [(η5-C5H5)2TiCN]2O

By the reaction of KCN with Cp₂TiCl₂ (Cp = η⁵-C₅H₅) in boiling methanol, bis(cyclopentadienyl)-methoxytitanium(IV) cyanide, Cp₂Ti(OCH₃)CN, is formed which in air is converted into the dinuclear oxygen-bridged derivative (Cp₂TiCN)₂O. By the same procedure, the bis(methylcyclopentadienyl) analogue [MeCp₂TiCN]₂O has been obtained. An X-ray diffraction study of (Cp₂TiCN)₂O has shown that the CN group acts as a unidentate ligand with a Ti? C bond length of 2.158 Å and a Ti? C? N bond angle of 177.7°, very close to linearity. The Ti? O bond distance, 1.836 Å, and the bond angle at the bridging O atom, 174.1°, are normal. The ligands are arranged in a nearly tetrahedral way around the Ti atoms. The structural results are compared to those for similar dinuclear titanium complexes.     

Influence of Hydrogen Bonding in the Structure of Mixed-Ligand Copper(II) Chelates. Spectra and Structure of [Aquo((2,2′-Dipyridylamine)-(3-Chloro-2,4-Pentanedionato)Copper(II)] Nitrate

The IR, the ligand field spectra and the crystal structure of the mixed-ligand compound [(aquo)2,2-dipyridylamine(3-chloro-2,4-pentanedionato)copper(II)] nitrate, [Cu(dpyamH) Cl-acac(H₂O)]NO₃], are reported. The copper atom exists in a square pyramidal environment with the apical position occupied by the aqua ligand. The nitrogenous base and the -dionato anion act as bidentate ligands forming six-membered chelate rings. In addition to the coulombic interactions with the metal centre, the planar NO ₃ ^- group participates in specific electrostatic interactions involving the hydrogen atoms of the coordinated water molecule. The chlorine and the nitrogen atoms are also involved in hydrogen bonding. The structure of the compound was determined by single crystal X-ray diffraction analysis (triclinic, space group , a = 8.718(5), b = 9.407(5), c = 13.484 (7) Å, = 94.17(4)°, = 105.12(5)°, = 119.75(5)°, Z = 2, R = 0.0332, R _W = 0.0869).     

Reaction of titanocene dihalides with Na2H2 EDTA. Crystal structure of [Ti(EDTA)(H2O)]

Summary Titanocene complexes ([Ti(⁵-C₅H₄ R)₂ X ₂];R = H, SiMe₃;X=Cl, Br) react with Na₂H₂ EDTA in aqueous methanol to give an identical product ([Ti(EDTA)(H₂O)] by cleavage of the halogen and cyclopentadienyl ligands. The structure of [Ti(EDTA)(H₂O)] has been determined by X-ray diffraction; crystal data: monoclinica=13.923(6),b=7.048(3),c=13.252(5) Å, =90.81(1)°, space groupP2₁/c,Z=4. In this complex, Ti has a sevenfold coordination with a hexadentateEDTA ^4– ligand and a water molecule occupying an additional coordination site.

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Reaktion von Titanocen-Dihalogeniden mit Na₂H₂ EDTA. Kristallstruktur von [Ti(EDTA)(H₂O)]

Zusammenfassung Titanocenkomplexe ([Ti(⁵-C₅H₄ R)₂ X ₂];R=H, SiMe₃;X=Cl, Br) reagieren in wäßrigem Methanol mit Na₂H₂ EDTA unter Verdrängung der Halogen- und Cyclopentadienylliganden zum selben Produkt ([Ti(EDTA)(H₂O)]). Die Struktur von ([Ti(EDTA)(H₂O)]) wurde röntgenographisch bestimmt. Kristalldaten: monoklin,a=13.923(6),b=7.048(3),c=13.252(5) Å, =90.81(1)°, RaumgruppeP2₁/c,Z=4. In diesem Komplex ist das Titanatom mit einem sechszähnigenEDTA-Liganden und einem Wassermolekül, das eine zusätzliche Koordinationsstelle besetzt, siebenfach koordiniert.

     

Self-Assemblies and Supramolecular Structures in Metal β-Dionates: Crystal and Molecular Structure of Bis(aquo)bis(3-cyano-2,4-pentanedionato)zinc(II) Dihydrate, [Zn(H2O)2(NC-acac)2] · 2H2O

Zinc(II) reacts with the anion of 3-cyano-2,4-pentanedione to form the coordinatively unsaturated bis(β-dionato)zinc(II) chelate that functions as Lewis acid and induces short-range site-bounded cohesion forces. Water molecules add to the metal center while others participate in specific interactions involving the terminal nitrogen atom. The X-ray structure analysis of the [Zn(H₂O)₂(NC-acac)₂] · 2H₂O entity (monoclinic, space group P2₁/c, a = 5.208(5), b = 21.359(5), c = 7.813(5) Å, β = 101.89(3)°, Z = 4, R = 0.0632, R _w = 0.0679) revealed that zinc(II) exists in a centrosymmetric distorted tetragonal environment and that the entity performs as a building block of a supramolecular structure.     

New 1,1′-Ring-substituted Vanadocene Dichlorides. Crystal structures of [V(η5-C5H4SiMe3)2Cl2] and [V(η5-C5H5)2Cl2]

The 1,1′-ring-substituted vanadocene dichlorides [V(η⁵-C₅H₄R)₂Cl₂] (R = CMe₃, SiMe₃, SiEt₃) have been prepared from VCl₄ and the appropriate lithiated cyclopentadiene, C₅H₄RLi, in 1 : 2 ratios. All complexes were characterized by elemental microanalysis and IR spectroscopy. The crystal structures of [V(η⁵-C₅H₄SiMe₃)₂Cl₂] 3 and the parent compound [V(η⁵-C₅H₅)₂Cl₂] 1 have been determined by X-ray diffraction and are in accordance with expectations. Compound 1 crystallizes with two crystallographically independent molecules in its monoclinic unit cell. These two molecules are quite similar in their essential structural features. Compound 3 crystallizes in the triclinic space group P1 . The trimethylsilylcyclopentadienyl rings are bound in a staggered relative orientation.     

Sulfur-Selenium Chelates: Crystal structure of the first titanocene derivative Ti(η5-C5H5)2SSe4

The crystal structure of bis(η⁵-cyclopentadienyl)titana(Ti^IV)-thiacyclohexaselenane, Ti(η⁵-C₅H₅)₂SSe₄ ( 1 ), has been determined by X-ray diffraction data. ( 1 ) crystallizes in the monoclinic space group P2₁/c with four formula units in the unit cell. The cell dimensions are a = 13.179, b = 8.087, c = 14.447 Å, β = 114.857°. The six-membered heterocycle TiSSe₄ has the expected chair conformation. In the chelate ring the Ti atom is S- and Se-bonded. The geometry of ( 1 ) corresponds closely to that of Ti(→⁵-C₅H₅)₂Se₅.     

New [Ti(η5-C5H5)Cl2(OR)] complexes. Crystal and molecular structure of η5-Cyclopentadienyl(cyclohexoxy)titanium(IV) dichloride

Summary A series of new compounds with molecular formula [Ti(⁵-C₅H₅)Cl₂(OR)] (R=C₆H₁₁ (cyclohexyl,1), CH₂CH(CH₃)₂ (2), CH(C₂H₅)₂ (3), and CH₂C₆H₅ (4)) has been obtained by the reaction of [Ti(⁵-C₅H₅)Cl₃] with the appropriate alcohol. All complexes were characterized by elemental analysis and by IR and¹H NMR spectroscopy. The structure of1 was determined by X-ray diffraction studies; crystal data: triclinic,a=11.334(2),b=13.590(2),c=12.237(2) Å, =113.501(5), =118.182(5), =101.993(6),V=1328.2(4) ų,T=298K, space P1,Z=4, two crystallographically independent molecules in the unit cell. FinalR andR _w values are 0.0583 and 0.0632, respectively. Compound1 exhibits surprisingly short Ti-Cl and Ti-O distances, suggesting strong donation by the chloride and in particular by the alkoxide ligand. The Ti-O-C angle is unusually large.

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Neue [Ti(⁵-C₅H₅)Cl₂(OR)]-Komplexe. Kristall- und Molekülstruktur von ⁵-Cyclopentadienyl(cyclohexoxy)titan(IV) Dichlorid

Zusammenfassung Durch Umsetzung von [Ti(⁵-C₅H₅)Cl₃] mit dem geeigneten Alkohol wurde eine Reihe von neuen Verbindungen der Formel [Ti(⁵-C₅H₅)(OR)] (R=C₆H₁₁ (cyclohexyl,1), CH₂CH(CH₃)₂ (2), CH(C₂H₅)₂ (3) und CH₂C₆H₅ (4)) erhalten. Alle Komplexe wurden elementaranalytisch sowie IR- und¹H-NMR-spektroskopisch charakterisiert. Die Struktur von1 wurde röntgenographisch bestimmt; Kristalldaten: triklin,a=11.334(2),b=13.590(2),c=12.237(2) Å, =113.501(5), =118.182(5), =101.993(6),V=1328.2(4) ų,T=298K, Raumgruppe P1,Z=4, zwei kristallographisch unabhängige Moleküle in der Elementarzelle; abschließendeR-Werte:R=0.0583 undR _w=0.0632. Verbindung1 zeigt überraschend kurze Ti-Cl- und Ti-O-Abstände; dies deutet auf eine starke -Elektronendonorwirkung des Chlorid- und vor allem des Alkoxidliganden hin. Der Ti-O-C-Bindungswinkel ist ungewöhnlich groß.

     

Novel lanthanide complexeswith di-2-pyridyl ketone-<Emphasis Type="Italic">p</Emphasis>-chloro-benzoylhydrazone

The reaction of a hydrated nitrate salt of lanthanide(III) (Ln=Er, Ho, Tb, Gd) or yttrium(III) (Y) with the ligand di-2-pyridyl ketone-p-Cl-benzoylhydrazone (DpkClBH), afforded air stable solid compounds. The new complexes characterized by means of elemental analysis (C, H, N, Ln), magnetic moment determinations and spectroscopic data (IR, MS). It is proposed that they are cationic of the general type: [Ln(DpkClBH)₂(NO₃)₂]NO₃·nH₂O, (n=2, 1, 1, 1, 1.5 for Ln=Y, Gd, Tb, Ho, Er, respectively). Their thermal decomposition was studied in nitrogen atmosphere, between 25–980°C, by using simultaneous TG/DTG-DTA technique. The IR spectroscopy used to determine the intermediates and the final products. The anhydrous nitrate complexes decomposed to the intermediates Ln(DpkClBH)(NO₃)₂, which upon further heating give a carbonaceous residue of Ln₂O₃ at 980°C. The mass spectra revealed the molecular ions of the complexes and their possible fragmentation pattern.     

Synthesis and a UV and IR spectral study of some 2-aryl-Δ-2-1,3,4-oxadiazoline-5-thiones

Twenty four 2-Aryl-Δ-²-1,3,4-oxadiazoline-5-thione derivatives 2 were synthesized and their uv and ir spectra were studied. Correlation between σ-Hammett constants of aryl substituents and the differences in absorption maxima (Δv = v₁-v₂ in kK) of the electronic spectra of the deprotonated species were also evaluated. A new method for the synthesis of the 2-(amino)aryl derivatives 2v,w,x is also reported.