Title: The Chemistry of Ca<sup>II</sup> and Yb<sup>II</sup>: Astoundingly Similar But Not Equal!
Abstract: Angewandte Chemie International EditionVolume 43, Issue 20 p. 2714-2718 Communication The Chemistry of CaII and YbII: Astoundingly Similar But Not Equal!† Sjoerd Harder Priv.-Doz. Dr., Sjoerd Harder Priv.-Doz. Dr. [email protected] Fachbereich Chemie, Universität Konstanz, Postfach 5560, M738, 78457 Konstanz, Germany, Fax: (+49) 7531-883-137 New Address: Institut für Anorganische Chemie, Universität Duisburg-Essen, 45117 Essen, GermanySearch for more papers by this author Sjoerd Harder Priv.-Doz. Dr., Sjoerd Harder Priv.-Doz. Dr. [email protected] Fachbereich Chemie, Universität Konstanz, Postfach 5560, M738, 78457 Konstanz, Germany, Fax: (+49) 7531-883-137 New Address: Institut für Anorganische Chemie, Universität Duisburg-Essen, 45117 Essen, GermanySearch for more papers by this author First published: 05 May 2004 https://doi.org/10.1002/anie.200353557Citations: 170 † This work was generously supported by the Deutsche Forschungsgemeinschaft and the BASF-AG (Ludwigshafen, Germany). Prof. Dr. H.-H. Brintzinger (Universität Konstanz), Dr. K. Knoll (BASF-AG) and Dr. M. Ishaque (BASF-AG) are thanked for discussions. Measurement of 600 MHz NMR spectra by A. Friemel and U. Haunz is immensely appreciated. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Graphical Abstract Not a red/green stereographic, but a plot showing the striking similarity between a Ca and Yb complex. The molecular structures, and the NMR and IR spectra of these Ca/Yb benzyl complexes are nearly identical. However, their reactivity in styrene polymerization is completely different: an internally coordinated dibenzylytterbium(II) complex produces polystyrene of high syndiotacticity (r=94.9 %, rr=90.0 %). Supporting Information Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2004/z53557_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. References 1 1aT. P. Hanusa, Coord. Chem. Rev. 2000, 210, 329; 1bM. Westerhausen, Angew. Chem. 2001, 113, 3063; Angew. Chem. Int. Ed. 2001, 40, 2975; 1cJ. S. Alexander, K. Ruhlandt-Senge, Eur. J. Inorg. Chem. 2002, 2761. 2Remarkably similar IR-spectra have been reported for the pairs [(MeCp)2Ca]⋅DME/[(MeCp)2Yb]⋅DME and [(cot)Ca]/[(cot)Yb] (cot is cyclooctatetraene) apart from low-frequency skeletal vibrations involving the metal: A. Hammel, W. Schwarz, J. Weidlein, J. Organomet. Chem. 1989, 378, 347. 3R. A. Williams, T. P. Hanusa, J. C. Huffman, Organometallics 1990, 9, 1128. 4R. A. Williams, T. P. Hanusa, J. C. Huffman, J. Am. Chem. Soc. 1990, 112, 2454. 5M. Rieckhoff, U. Pieper, D. Stalke, F. T. Edelmann, Angew. Chem. 1993, 105, 1102; Angew. Chem. Int. Ed. Engl. 1993, 32, 1079. 6D. Stalke, Angew. Chem. 1994, 106, 2256; Angew. Chem. Int. Ed. Engl. 1994, 33, 2168. 7C. Eaborn, P. B. Hitchcock, K. Izod, Z.-R. Lu, J. D. Smith, Organometallics 1996, 15, 4783. 8K. Izod, W. Clegg, S. T. Liddle, Organometallics 2000, 19, 3640. 9I. L. Fedushkin, T. V. Petrovskaya, M. N. Bochkarev, S. Dechert, H. Schumann, Angew. Chem. 2001, 113, 2540; Angew. Chem. Int. Ed. 2001, 40, 2474. 10F. Weber, H. Sitzmann, M. Schultz, C. D. Sofield, R. A. Andersen, Organometallics 2002, 21, 3139. 11S. Harder, Angew. Chem. 2003, 115, 3553; Angew. Chem. Int. Ed. 2003, 42, 3430. 12Reviews: 12aT. J. Marks, Prog. Inorg. Chem. 1978, 24, 51–107; 12bW. J. Evans, Polyhedron 1987, 6, 803; 12cR. Anwander, W. A. Herrmann, Top. Curr. Chem. 1996, 179, 1–32; 12dR. Anwander, Top. Organomet. Chem. 1999, 2, 1–61; 12eF. T. Edelmann, D. M. M. Freckmann, H. Schuhmann, Chem. Rev. 2002, 102, 1861; Recently also the first ScII, LaII, NdII, DyII, and TmII compounds were synthesized: 12fP. L. Arnold, F. G. N. Cloke, P. B. Hitchcock, J. F. Nixon, J. Am. Chem. Soc. 1996, 118, 7630; 12gM. Cassani, D. J. Duncalf, M. F. Lappert, J. Am. Chem. Soc. 1998, 120, 12 958; 12hM. N. Bochkarev, A. A. Fagin, Chem. Eur. J. 1999, 5, 2990; 12iM. N. Bochkarev, I. L. Fedushkin, A. A. Fagin, T. V. Petrovskaya, J. W. Ziller, R. N. R. Broomhall-Dillard, W. J. Evans, Angew. Chem. 1997, 109, 123; Angew. Chem. Int. Ed. Engl. 1997, 36, 133. 13R. A. Andersen, J. M. Boncella, C. J. Burns, R. Blom, A. Haaland, H. V. Volden, J. Organomet. Chem. 1986, 312, C 49; 13bM. Kaupp, P. von R. Schleyer, M. Dolg, H. Stoll, J. Am. Chem. Soc. 1992, 114, 8202. 14R. D. Shannon, Acta Crystallogr. Sect. A 1976, 32, 751. 15S. Harder, F. Feil, A. Weeber, Organometallics 2001, 20, 1044. 16S. Harder, F. Feil, T. Repo, Chem. Eur. J. 2002, 8, 1992. 17S. Harder, Organometallics 2002, 21, 3782. 18Selected bond lengths [Å] and angles [°] for 3(Yb) and 3(Ca) (values for 3(Ca) are in square brackets): MN1 2.382(2) [2.374(1)]; MN2 2.398(2) [2.384(1)]; N1-M-N2 83.11(7) [83.09(4)].[17] 19Selected bond lengths [Å] for 4(Yb) and 4(Ca) (the values for 4(Ca) are in square brackets): MC1 2.564(4) [2.594(3)]; MC2 2.862(4) [2.824(2)]; MC3 2.798(4) [2.777(3)]; MC4 2.856(4) [2.832(4)]; MN1′ 2.385(3) [2.361(2)]; MN2 2.451(3) [2.418(2)]. Atom numbering is as shown in reference [11]. 20S. Harder, F. Feil, K. Knoll, Angew. Chem. 2001, 113, 4391; Angew. Chem. Int. Ed. 2001, 40, 4261. 21It was also extremely difficult to obtain single crystals of 5(Ca). Crystal data for 5(Yb) and 5(Ca) (values for 5(Ca) are given in square brackets) are similar: a 13.42(6) [13.598(1)]; b 16.87(5) [16.824(1)]; c 18.45(8) [18.203(2)]; α 68.7(2) [70.779(6)]; β 69.9(2) [77.084(7)]; γ 82.5(4) [82.671(7)]; V 3656(26) [3826.1(6)]. A rough structure determination for 5(Yb) confirms a similar composition and structure. 22 22aD. Hoffmann, W. Bauer, F. Hampel, N. J. R. van Eikema Hommes, P. von R. Schleyer, P. Otto, U. Pieper, D. Stalke, D. S. Wright, R. Snaith, J. Am. Chem. Soc. 1994, 116, 528; 22bF. Feil, S. Harder, Organometallics 2000, 19, 5010. 23The tacticity reported by us earlier (r=84 %, rr=76 %)[20] is based on a wrong, but at that time generally accepted, pentad assignment. The correct assignment, based on heptads, results in a higher syndiotacticity: F. Feil, S. Harder, Macromolecules 2003, 36, 3446. The values presented here were obtained by Gaussian fits. 24Stryrene polymerization with the two component system [CpYb]/KSiH3 was recently reported and yields atactic polystyrene: Z. Hou, Y. Zhang, M. Nishiura, Y. Wakatsuki, Organometallics 2003, 22, 129. 25G. B. Deacon, C. M. Forsyth, Organometallics 2003, 22, 1351. 26Addition of 0.05 mmol 1(Yb) to 100 mmol of styrene in 90 mL of cyclohexane at 50 °C produces a polymer with unimodal distribution: M̄w=111.000 (M̄w is the mass-average molecular mass, expected: ca. 103 000), D=1.50. As for 1(Ca) slow initiation and therefore tailing in the low molecular weight range is observed.[15,20] The polymerization with 1(Yb) shows characteristics of a living polymerization (e.g., linear relation of ln(M̄n) and polymerization time; M̄n is the number average molecular mass). We are currently investigating the extent of livingness and the possibility of preparing block copolymers with 1(Yb). 27The polymerization reactions follow pseudofirst-order kinetics in styrene. The following rate constants for polymerization (1 M styrene solution in cyclohexane) at 50 °C were measured: 1(Yb) k=8.2(2) L mol−1 s−1 and 1(Ca) k=2.5(1) L mol−1 s−1. 28F. Feil, S. Harder, Organometallics 2001, 20, 4616. 29Traces of oxygen could result in the partial oxidative coupling of polymer chains and lead to a similar bimodal distribution. The use of carefully dried and deoxygenated solvents makes this reaction unlikely in this case. 30W. J. Evans, T. A. Ulibarri, J. W. Ziller, J. Am. Chem. Soc. 1990, 112, 219. 31N. B. Mikheev, L. N. Aurmann, I. A. Rumer, Inorg. Chim. Acta 1985, 109, 217. 32L. Maron, L. Perrin, O. Eisenstein, R. A. Andersen, J. Am. Chem. Soc. 2002, 124, 5614. 33The colors of LnII species are usually more intense due to Laporte-allowed 4f→5d transitions: W. T. Carnall in Handbook of the Physics and Chemistry of Rare Earths (Eds: ), North-Holland Publishing Company, Amsterdam, 1979, chap. 24. Citing Literature Volume43, Issue20May 10, 2004Pages 2714-2718 ReferencesRelatedInformation
Publication Year: 2004
Publication Date: 2004-05-05
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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