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- ItemCrystal structure of bis{μ2-[(2-iminocyclopentylidene)methylidene]azanido-κ2 N:N'}bis[(η5-pentamethylcyclopentadienyl)zirconium(IV)] hexane monosolvate(Chester : International Union of Crystallography, 2015) Becker, Lisanne; Spannenberg, Anke; Arndt, Perdita; Rosenthal, UweThe title compound, [Zr2(C10H15)4(C6H6N2)2]·C6H14, was obtained by the stoichiometric reaction of adipoÂnitrile with [Zr(C10H15)2([eta]2-Me3SiC2SiMe3)]. IntraÂmolecular nitrile-nitrile couplings and deprotonation of the substrate produced the (1-imino-2-enimino)ÂcycloÂpentane ligand, which functions as a five-membered bridge between the two metal atoms. The ZrIV atom exhibits a distorted tetraÂhedral coordination sphere defined by two pentaÂmethylÂcycloÂpentaÂdienyl ligands, by the imino unit of one (1-imino-2-enimino)ÂcycloÂpentane and by the enimino unit of the second (1-imino-2-enimino)ÂcycloÂpentane. The cycloÂpentane ring of the ligand shows an envelope conformation. The asymmetric unit contains one half of the complex and one half of the hexane solvent molÂecule, both being completed by the application of inversion symmetry. One of the pentaÂmethylÂcycloÂpentaÂdienyl ligands is disordered over two sets of sites with a refined occupancy ratio of 0.8111 (3):0.189 (3). In the crystal, the complex molÂecules are packed into rods extending along [100], with the solvent molÂecules located in between. The rods are arranged in a distorted hexaÂgonal packing.
- ItemCrystal structure of di-n-butÂylÂbisÂ([eta]5-pentaÂmethylÂcycloÂpentaÂdienÂyl)hafnium(IV)(Chester : International Union of Crystallography, 2015) Arndt, Perdita; Schubert,Kathleen; Burlakov, Vladimir V.; Spannenberg, Anke; Rosenthal, UweThe crystal structure of the title compound, [Hf(C10H15)2(C4H9)2], reveals two independent molÂecules in the asymmetric unit. The diffraction experiment was performed with a racemically twinned crystal showing a 0.529 (5):0.471 (5) component ratio. Each HfIV atom is coordinated by two pentaÂmethylÂcycloÂpentaÂdienyl and two n-butyl ligands in a distorted tetraÂhedral geometry, with the cycloÂpentaÂdienyl rings inclined to one another by 45.11 (15) and 45.37 (16)°. In contrast to the isostructural di(n-butyl)bis([eta]5-pentaÂmethylÂcycloÂpentaÂdienÂyl)zirconium(IV) complex with a noticeable difference in the Zr-butyl bonding, the Hf-CbutÂyl bond lengths differ from each other by no more than 0.039 (3) Ã….
- ItemCrystal structure of bis(η5-cyclopenta-dienyl)(2, 3-diethylbutane-1, 4-diyl)-hafnium(IV)(Chester : International Union of Crystallography, 2015) Burlakov, Vladimir V.; Baumann, Wolfgang; Arndt, Perdita; Spannenberg, Anke; Rosenthal, UweThe title compound, [Hf(C5H5)2(C8H16)], proves a structural motif of hafnaÂcycloÂpentane besides the coordination of two cycloÂpentaÂdienyl ligands in an [eta]5-fashion. The hafnaÂcycloÂpentane ring has a twist conformation and is substituted by two ethyl groups in the [beta],[beta]'-positions, which are trans orientated to each other. One cycloÂpentaÂdienyl ring and one ethyl group are each disordered over two positions with site-occupancy ratios of 0.679 (15):0.321 (15) and 0.702 (18):0.298 (18), respectively.
- ItemSynthesis and crystallographic characterization of [2,2-bisÂ(η5-pentaÂmethylÂcycloÂpentaÂdienÂyl)-3,4-bis(triÂmethylÂsilÂyl)-2-zirconaÂfuran-5-one-κO5]triisobutylÂaluminium(Chester : International Union of Crystallography, 2018-3-27) Burlakov, Vladimir V.; Bogdanov, Vyacheslav S.; Arndt, Perdita; Spannenberg, Anke; Rosenthal, Uwe; Beweries, Torsten; Shur, Vladimir B.The crystal structure of the title zwitterionic zirconocene complex containing a furanÂone unit, [AlZr(C10H15)2(C4H9)3(C9H18O2Si2)], is reported. On reacting a zirconaÂfuranÂone with two equivalents of HAl(i-Bu)2, disproportionation of the Lewis acid results in the formation of a triisoÂbutylÂaluminium fragment, Al(i-Bu)3, which coordinates to the exocyclic carbonyl O atom of the zirconaÂfuranÂone ring. Single-crystal X-ray diffraction reveals that the zirconaÂfuranÂone ring remains intact with coordination of the aluminium to the exocyclic O atom. One of the i-butyl groups is disordered over two sets of sites, with an occupancy ratio of 0.731 (3):0.269 (3).
- ItemCrystal structure of bis(η5-cyclopenta-dienyl)(1,4-di-tert-butylbuta-1-en-3-yn-1-yl) zirconium(IV) μ2-hydroxido-bis[tris-(pentafluorophenyl) borate](Chester : International Union of Crystallography, 2015) Burlakov, Vladimir V.; Spannenberg, Anke; Arndt, Perdita; Rosenthal, UweAlkyl zirconocene cations have been of considerable interÂest as reactive species in many polymerization processes. In the crystal structure of the title compound, [Zr(C12H19)(C5H5)2](C36HB2F30O), the [Zr(C5H5)2((t-Bu)C=C(H)-C2(t-Bu))]+ cation displays a buta-1-en-3-yne ligand side-on coordinated to a typical bent zirconocene [centroid(cp)-Zr-centroid(cp) = 131.4 (3)°, Zr-C(buta-1-en-3-yne) = 2.255 (3), 2.597 (3) and 2.452 (2) Ã…]. In the [HO(B(C6F5)3)2]- anion, intraÂmolecular O-H...F hydrogen bonds are observed. One tert-butyl group in the complex cation is disordered over two sets of sites with occupancies 0.701(4):0.299(4).
- Item1-Titanacyclobuta-2,3-diene-an elusive four-membered cyclic allene(Cambridge : RSC, 2019) Reiß, Fabian; Reiß, Melanie; Bresien, Jonas; Spannenberg, Anke; Jiao, Haijun; Baumann, Wolfgang; Arndt, Perdita; Beweries, TorstenThe synthesis of an unusual 1-metalla-2,3-cyclobutadiene complex [rac-(ebthi)Ti(Me3SiC3SiMe3)] (rac-ebthi = rac-1,2-ethylene-1,1′-bis(η5-tetrahydroindenyl)), a formal metallacyclic analogue of a non-existent four-membered 1,2-cyclobutadiene, is described. By variation of the cyclopentadienyl ligand of the titanocene precursor it was possible to stabilise this highly exotic compound which selectively reacts with ketones and aldehydes to yield enynes by oxygen transfer to titanium. Analysis of the bonding and electronic structure of the metallacycle shows that the complex is best described as an unusual antiferromagnetically coupled biradicaloid system, possessing a formal Ti(iii) centre coordinated with a monoanionic radical ligand. © 2019 The Royal Society of Chemistry.
- ItemA second polymorph of 3,4-bisÂÂ(6-bromoÂpyridin-3-yl)-1,2,5-thiaÂdiazole(Chester : International Union of Crystallography, 2016) Becker, Lisanne; Altenburger, Kai; Spannenberg, Anke; Arndt, Perdita; Rosenthal, UweThe title compound, C12H6Br2N4S, a second polymorph in the triclinic space group P-1, is presented. As in the earlier reported monoclinic polymorph in the space group C2/c [Becker et al. (2016[Becker, L., Reiss, F., Altenburger, K., Spannenberg, A., Arndt, P., Jiao, H. & Rosenthal, U. (2016). Chem. Eur. J. In the press. doi: 10.1002/chem.201601337.]). Chem. Eur. J. In the press], the thiaÂdiazole ring is planar with an r.m.s. deviation of 0.004 Å. The five-membered ring is tilted with respect to the two pyridyl substituents by 23.16 (7) and 49.47 (9)°. In the crystal, molÂecules are linked by a weak non-bonding Br⋯N interÂaction [3.056 (3) Å]. Furthermore, a column of molÂecules is established along the b axis by π–π stacking interÂactions between the pyridine rings [centroid–centroid distances = 3.7014 (16) and 3.5934 (15) Å]. Additionally, a short interÂmolecular Br⋯Br contact [3.3791 (6) Å] and Br⋯π-aryl contacts [3.6815 (11)–3.7659 (12) Å] towards the thiaÂdiazole and pyridine rings are found.