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<title>UTas ePrints - Design and Performance of Rigid Nanosize Multimetallic Cartwheel Pincer Compounds as Lewis-Acid Catalysts</title>
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<meta content="Dijkstra, H.P." name="eprints.creators_name" />
<meta content="Meijer, M.D." name="eprints.creators_name" />
<meta content="Patel, J." name="eprints.creators_name" />
<meta content="Kreiter, R." name="eprints.creators_name" />
<meta content="van Klink, G.P.M." name="eprints.creators_name" />
<meta content="Lutz, M." name="eprints.creators_name" />
<meta content="Spek, A.L." name="eprints.creators_name" />
<meta content="Canty, A.J." name="eprints.creators_name" />
<meta content="van Koten, G." name="eprints.creators_name" />
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<meta content="Design and Performance of Rigid Nanosize Multimetallic
Cartwheel Pincer Compounds as Lewis-Acid Catalysts" name="eprints.title" />
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<meta content="Novel strategies for the preparation of rigid cartwheel pincer metal complexes have been developed. The aromatic backbone of these materials ensures a high rigidity, which is expected to be important for a high retention when these multimetallic nanosize complexes are applied as homogeneous catalysts in a nanomembrane reactor. The ligand precursors C6[C6H3(CH2Y)2-3,5]6 (10, Y = NMe2; 11, Y = SPh; 12, Y = PPh2; 13, Y = pz = pyrazol-1-yl) have been prepared in high yields from the key intermediate C6[C6H3(CH2Br)2-3,5]6 (9). The hexakis(pincer) palladium(II) complexes C6[(PdX)-4-C6H2(CH2Y)2-3,5]6 (14, Y = SPh, L =
Cl; 15, Y = PPh2, L = Cl; 16, Y = pyrazol-1-yl, L = OAc; 17, Y = pyrazol-1-yl, L = Cl) have been prepared via direct electrophilic palladation of the corresponding ligands. The (tris)pincer ligand C6H3[Br-4-C6H3(CH2NMe2)2-3,5]3-1,3,5 (20) was prepared via a triple condensation
reaction of 4-bromo-3,5-bis[(dimethylamino)methyl]acetophenone (19). Reaction of 20 with Pd(dba)2 yielded the tripalladium complex C6H3[(PdBr)-4-C6H3(CH2NMe2)2-3,5]3-1,3,5 (21). The crystal structure of 21 shows a propeller-like structure with D3 symmetry and a fixed bromine-bromine distance of 17.4573(4) Å, approximately forming a triangle with a height of 15.2 Å. These nanosize cartwheel pincer metal complexes based on tridentate
Y,C,Y' pincer ligands have been used as homogeneous Lewis-acid catalysts. Moreover, the influence of the donor substituent Y on the catalytic activity of cationic mono-Y,C,Y' Pd(II) complexes as Lewis-acid catalysts in the double Michael reaction between methyl vinyl ketone
and ethyl alpha-cyanoacetate, as a model reaction, has been investigated. It was found that cationic N,C,N'-type pincer complexes (1a, Y = NMe2; 1b, Y = pz; 1c, Y = pz* =
3,5-dimethylpyrazol-1-yl; 23) were superior to the P,C,P'- and S,C,S¢-pincer complexes (1d, Y = PPh2; 1e, Y = SPh). The nanosize cationic tri-N,C,N Pd'(II) complex 23 was found to have a catalytic activity per catalytic site in the double Michael reaction of the same order of
magnitude as the monopincer analogue 1a (k = 279 x 10-6 s-1 for 1a vs k = 232 x 10-6 s-1 for 23). The combination of the nanosize dimensions, the catalytic activity, and the high thermal and air stability makes these complexes excellent candidates for application in a continuous process in a nanomembrane reactor." name="eprints.abstract" />
<meta content="2001" name="eprints.date" />
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<meta content="Organometallics" name="eprints.publication" />
<meta content="20" name="eprints.volume" />
<meta content="14" name="eprints.number" />
<meta content="3159-3168" name="eprints.pagerange" />
<meta content=" 10.1021/om0101689" name="eprints.id_number" />
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(1) For a review on the application of metallodendrimers as homogeneous
catalysts, see: Kreiter, R.; Kleij, A. W.; Klein Gebbink, R. J.
M.; van Koten, G. Topics in Current Chemistry, Dendrimers IV by Prof.
Dr. F. Vo¨gtle.
(2) (a) Knapen, J. W. J.; van der Made, A. W.; de Wilde, J. C.; van
Leeuwen, P. W. N. M.; Wijkens, P.; Grove, D. M.; van Koten, G. Nature
1994, 372, 659. (b) Kragl, U.; Dreisbach, C. Angew. Chem., Int. Ed.
Engl. 1996, 35, 642. (c) Reetz, M. T.; Lohmer, G.; Schwickardi, R.
Angew. Chem., Int. Ed. 1997, 36, 1526. (d) Giffels, G.; Beliczey, J.;
Felder, M.; Kragl, U. Tetrahedron: Asymmetry 1998, 9, 691. (e)
Brinkmann, N.; Giebel, D.; Lohmer, G.; Reetz, M. T.; Kragl, U. J. Catal.
1999, 183, 163. (f) Hovestad, N. J.; Eggeling, E. B.; Heidbu¨ chel, H. J.;
Jastrzebski, J. T. B. H.; Kragl. U.; Keim, W.; Vogt, D.; van Koten, G.
Angew. Chem., Int. Ed. 1999, 38, 1655. (g) De Groot, D.; Eggeling, E.
B.; de Wilde, J. C.; Kooijman, H.; van Haaren, R. J.; van der Made, A.
W.; Spek, A. L.; Vogt, D.; Reek, J. N. H.; Kamer, P. C. J.; van Leeuwen,
P. W. N. M. Chem. Commun. 1999, 1623. (h) Dijkstra, H. P.;
Steenwinkel, P.; Grove, D. M.; Lutz, M.; Spek, A. L.; van Koten, G.
Angew. Chem., Int. Ed. 1999, 38, 2186. (i) Albrecht, M.; Hovestad, N.
J.; Boersma, J.; van Koten, G. Chem. Eur. J. 2001, 7, 1289. (j) Kleij,
A. W.; Gossage, R. A.; Klein Gebbink, R. J. M.; Brinkman, N.; Reijerse,
E. J.; Kragl, U.; Lutz, M.; Spek, A. L.; van Koten, G. J. Am. Chem.
Soc. 2000, 122, 12112.
(3) (a) Mahrwald, R. Chem. Rev. 1999, 99, 1095 and references
therein. (b) Christoffers, J. Eur. J. Org. Chem. 1998, 1259 and
references therein. (c) Drury, W. J.; Ferraris, D.; Cox, C.; Young, B.;
Lectka, T. J. Am. Chem. Soc. 1998, 120, 11006.
(4) Diels-Alder Reactions: (a) Bruin, M. E.; Ku¨ ndig, E. P. Chem.
Commun. 1998, 2635. (b) Kanemasa, S.; Oderaotoshi, Y.; Sakaguchi,
S.-I.; Yamamoto, H.; Tanaka, J.; Wada, E.; Curran, D. J. Am. Chem.
Soc. 1998, 120, 3074. (c) Schaus, S. E.; Brånalt, J.; Jacobsen, E. N. J.
Org. Chem. 1998, 63, 403. (d) Davies, D. L.; Fawcett, J.; Garrat, S. A.;
Russell, D. R. Chem. Commun. 1997, 1351. (e) Evans, D. A.; Murry, J.
A.; von Matt, P.; Norcross, R. D.; Miller, S. J. Angew. Chem., Int. Ed.
Engl. 1995, 34, 798. (f) Ku¨ ndig, E. P.; Bourdin, B.; Bernardinelli, G.
Angew. Chem., Int. Ed. Engl. 1994, 33, 1856. (g) Corey, E. J.; Imai,
N.; Zhang, H.-Y. J. Am. Chem. Soc. 1991, 113, 728.
(5) Aldol reactions: (a) Fujimura, O. J. Am. Chem. Soc. 1998, 120,
10032. (b) Evans, D. A.; MacMillan, D. W. C.; Campos, K. R. J. Am.
Chem. Soc. 1997, 119, 10859. (c) Yanagisawa, A.; Matsumoto, Y.;
Nakashima, H.; Asakawa, K.; Yamamoto, H. J. Am. Chem. Soc. 1997,
119, 9319. (d) Evans, D. A.; Murry, J. A.; Kozlowski, M. C. J. Am.
Chem. Soc. 1996, 118, 5814. (e) Mikami, K.; Matsukawa, S. J. Am.
Chem. Soc. 1994, 116, 4077.
(6) Michael reactions: (a) Blacker, A. J.; Clarke, M. L.; Loft, M. S.;
Mahon, M. F.; Williams, J. M. J. Organometallics 1999, 18, 2867. (b)
Sawamura, M.; Hamashima, H.; Ito, Y. Tetrahedron 1994, 50, 4439.
(c) Evans, D. A.; Rovis, T.; Kozlowski, M. C.; Wade Downey, C.; Tedrow,
J. S. J. Am. Chem. Soc. 2000, 122, 9134.
(7) Alkylation reactions: (a) Ferraris, D.; Young, B.; Dudding, T.;
Lectka, T. J. Am. Chem. Soc. 1998, 120, 4548. (b) Yanagisawa, A.;
Nakashima, H.; Ishiba, A.; Yamamoto, H. J. Am. Chem. Soc. 1996,
118, 4723.
(8) (a) Gorla, F.; Togni, A.; Venanzi, L. M.; Albinati, A.; Lianza, F.
Organometallics 1994, 13, 1607. (b) Longmire, J. M.; Zhang, X.; Shang,
M. Organometallics 1998, 17, 4374.
(9) (a) Stark, M. A.; Richards, C. J. Tetrahedron Lett. 1997, 38, 5881.
(b) Stark, M. A.; Jones, G.; Richards, C. J. Organometallics 2000, 19,
1282.
(10) Motoyama, Y.; Narusawa, H.; Nishiyama, H. Chem. Commun.
1999, 131.
(11) For the synthesis of 3a see: Alsters, P. L.; Baesjou, P. J.;
Janssen, M. D.; Kooijman, H.; Sicherer-Roetman, A.; Spek, A. L.; van
Koten, G. Organometallics 1992, 11, 4124.
(12) For the synthesis of 1b and 3b see: Canty, A. J.; Honeyman,
R. T.; Skelton, B. W.; White, A. H. J. Organomet. Chem. 1990, 389,
277.
(13) For the synthesis of 1a from 3a see: Grove, D. M.; van Koten,
G.; Louwen, J. N.; Noltes, J. G.; Spek, A. L.; Ubbels, H. J. C. J. J. Am.
Chem. Soc. 1984, 104, 6609.
(14) Hartshorn, C. M.; Steel, P. J. Organometallics 1998, 17, 3487.
(15) (a) For the synthesis of 3d see: Rimml, H.; Venanzi, L. M. J.
Organomet. Chem. 1983, 259, C6. (b) For the synthesis of 3e see:
Lucena, N.; Casabo, J.; Escriche, L.; Sanchez-Castello, G.; Teixidor,
F.; Kiveka¨s, R.; Sillanpa¨a¨ , R. Polyhedron 1996, 15, 3009.
(16) Ducheˆne, K.-H.; Vo¨gtle, F. Synthesis 1986, 659.
(17) Sonogashira, K.; Tohda, Y.; Hagihara, N. Tetrahedron Lett.
1975, 4467.
(18) Procedure reported by: (a) Loeb, S. J.; Shimizu, G. K. H. J.
Chem. Soc., Chem. Commun. 1993, 1396. (b) Kickham, J. E.; Loeb, S.
J. Inorg. Chem. 1994, 33, 4351.
(19) Van de Kuil, L. A.; Luitjes, H.; Grove, D. M.; Zwikker, J. W.; ously reported.21 The neutral complex 21 can easily be
van der Linden, J. G. M.; Roelofsen, A. M.; Jenneskens, L. W.; Drenth,
W.; van Koten, G. Organometallics 1994, 13, 471.
(20) Modification of a reported method was used: Elmorsy, S. S.;
Pelter, A.; Smith, K. Tetrahedron Lett. 1991, 32, 4175.
21) Canty, A. J.; Patel, J.; Skelton, B. W.; White, A. H. J.
Organomet. Chem. 2000, 599, 195.
(22) Canty, A. J.; Lee, C. V. Organometallics 1982, 1, 1063.
(23) Dijkstra, H. P.; Kruithof, K.; Ronde, N.; Vogt, D.; van Klink,
G. P. M.; van Koten, G. To be submitted for publication. SelRo
nanofiltration membranes (MPF-60) were purchased from Koch Membrane
Systems Inc., Du¨ sseldorf, Germany; further product information
may be found at http://www.kochmembrane.com.
(24) Drew, D.; Doyle, J. R.; Shaver, A. G. Inorg. Synth. 1972, 13,
47.
(25) Derived values do not contain the contribution of the disordered
solvent.
26) Spek, A. L. PLATON: A Multipurpose Crystallographic Tool;
Utrecht University, The Netherlands, 2000.
(27) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.;
Garcia-Granda, S.; Gould, R. O.; Smits, J. M. M.; Smykalla, C. The
DIRDIF97 Program System, Technical Report of the Crystallography
Laboratory; University of Nijmegen, Nijmegen, The Netherlands, 1997.
(28) Sheldrick, G. M. SHELXL-97: Program for Crystal Structure
Refinement; University of Go¨ttingen, Go¨ttingen, Germany, 1997.
" name="eprints.referencetext" />
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<meta content="Novel strategies for the preparation of rigid cartwheel pincer metal complexes have been developed. The aromatic backbone of these materials ensures a high rigidity, which is expected to be important for a high retention when these multimetallic nanosize complexes are applied as homogeneous catalysts in a nanomembrane reactor. The ligand precursors C6[C6H3(CH2Y)2-3,5]6 (10, Y = NMe2; 11, Y = SPh; 12, Y = PPh2; 13, Y = pz = pyrazol-1-yl) have been prepared in high yields from the key intermediate C6[C6H3(CH2Br)2-3,5]6 (9). The hexakis(pincer) palladium(II) complexes C6[(PdX)-4-C6H2(CH2Y)2-3,5]6 (14, Y = SPh, L =
Cl; 15, Y = PPh2, L = Cl; 16, Y = pyrazol-1-yl, L = OAc; 17, Y = pyrazol-1-yl, L = Cl) have been prepared via direct electrophilic palladation of the corresponding ligands. The (tris)pincer ligand C6H3[Br-4-C6H3(CH2NMe2)2-3,5]3-1,3,5 (20) was prepared via a triple condensation
reaction of 4-bromo-3,5-bis[(dimethylamino)methyl]acetophenone (19). Reaction of 20 with Pd(dba)2 yielded the tripalladium complex C6H3[(PdBr)-4-C6H3(CH2NMe2)2-3,5]3-1,3,5 (21). The crystal structure of 21 shows a propeller-like structure with D3 symmetry and a fixed bromine-bromine distance of 17.4573(4) Å, approximately forming a triangle with a height of 15.2 Å. These nanosize cartwheel pincer metal complexes based on tridentate
Y,C,Y' pincer ligands have been used as homogeneous Lewis-acid catalysts. Moreover, the influence of the donor substituent Y on the catalytic activity of cationic mono-Y,C,Y' Pd(II) complexes as Lewis-acid catalysts in the double Michael reaction between methyl vinyl ketone
and ethyl alpha-cyanoacetate, as a model reaction, has been investigated. It was found that cationic N,C,N'-type pincer complexes (1a, Y = NMe2; 1b, Y = pz; 1c, Y = pz* =
3,5-dimethylpyrazol-1-yl; 23) were superior to the P,C,P'- and S,C,S¢-pincer complexes (1d, Y = PPh2; 1e, Y = SPh). The nanosize cationic tri-N,C,N Pd'(II) complex 23 was found to have a catalytic activity per catalytic site in the double Michael reaction of the same order of
magnitude as the monopincer analogue 1a (k = 279 x 10-6 s-1 for 1a vs k = 232 x 10-6 s-1 for 23). The combination of the nanosize dimensions, the catalytic activity, and the high thermal and air stability makes these complexes excellent candidates for application in a continuous process in a nanomembrane reactor." name="DC.description" />
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<h1 class="ep_tm_pagetitle">Design and Performance of Rigid Nanosize Multimetallic Cartwheel Pincer Compounds as Lewis-Acid Catalysts</h1>
<p style="margin-bottom: 1em" class="not_ep_block"><span class="person_name">Dijkstra, H.P.</span> and <span class="person_name">Meijer, M.D.</span> and <span class="person_name">Patel, J.</span> and <span class="person_name">Kreiter, R.</span> and <span class="person_name">van Klink, G.P.M.</span> and <span class="person_name">Lutz, M.</span> and <span class="person_name">Spek, A.L.</span> and <span class="person_name">Canty, A.J.</span> and <span class="person_name">van Koten, G.</span> (2001) <xhtml:em>Design and Performance of Rigid Nanosize Multimetallic Cartwheel Pincer Compounds as Lewis-Acid Catalysts.</xhtml:em> Organometallics, 20 (14). pp. 3159-3168. ISSN 0276-7333</p><p style="margin-bottom: 1em" class="not_ep_block"></p><table style="margin-bottom: 1em" class="not_ep_block"><tr><td valign="top" style="text-align:center"><a href="http://eprints.utas.edu.au/2865/1/Organomet2001_2C_3159.pdf"><img alt="[img]" src="http://eprints.utas.edu.au/style/images/fileicons/application_pdf.png" class="ep_doc_icon" border="0" /></a></td><td valign="top"><a href="http://eprints.utas.edu.au/2865/1/Organomet2001_2C_3159.pdf"><span class="ep_document_citation">PDF</span></a> - Full text restricted - Requires a PDF viewer<br />179Kb</td><td><form method="get" accept-charset="utf-8" action="http://eprints.utas.edu.au/cgi/request_doc"><input accept-charset="utf-8" value="4085" name="docid" type="hidden" /><div class=""><input value="Request a copy" name="_action_null" class="ep_form_action_button" onclick="return EPJS_button_pushed( '_action_null' )" type="submit" /> </div></form></td></tr></table><p style="margin-bottom: 1em" class="not_ep_block">Official URL: <a href="http://dx.doi.org/10.1021/om0101689">http://dx.doi.org/10.1021/om0101689</a></p><div class="not_ep_block"><h2>Abstract</h2><p style="padding-bottom: 16px; text-align: left; margin: 1em auto 0em auto">Novel strategies for the preparation of rigid cartwheel pincer metal complexes have been developed. The aromatic backbone of these materials ensures a high rigidity, which is expected to be important for a high retention when these multimetallic nanosize complexes are applied as homogeneous catalysts in a nanomembrane reactor. The ligand precursors C6[C6H3(CH2Y)2-3,5]6 (10, Y = NMe2; 11, Y = SPh; 12, Y = PPh2; 13, Y = pz = pyrazol-1-yl) have been prepared in high yields from the key intermediate C6[C6H3(CH2Br)2-3,5]6 (9). The hexakis(pincer) palladium(II) complexes C6[(PdX)-4-C6H2(CH2Y)2-3,5]6 (14, Y = SPh, L =
Cl; 15, Y = PPh2, L = Cl; 16, Y = pyrazol-1-yl, L = OAc; 17, Y = pyrazol-1-yl, L = Cl) have been prepared via direct electrophilic palladation of the corresponding ligands. The (tris)pincer ligand C6H3[Br-4-C6H3(CH2NMe2)2-3,5]3-1,3,5 (20) was prepared via a triple condensation
reaction of 4-bromo-3,5-bis[(dimethylamino)methyl]acetophenone (19). Reaction of 20 with Pd(dba)2 yielded the tripalladium complex C6H3[(PdBr)-4-C6H3(CH2NMe2)2-3,5]3-1,3,5 (21). The crystal structure of 21 shows a propeller-like structure with D3 symmetry and a fixed bromine-bromine distance of 17.4573(4) Å, approximately forming a triangle with a height of 15.2 Å. These nanosize cartwheel pincer metal complexes based on tridentate
Y,C,Y' pincer ligands have been used as homogeneous Lewis-acid catalysts. Moreover, the influence of the donor substituent Y on the catalytic activity of cationic mono-Y,C,Y' Pd(II) complexes as Lewis-acid catalysts in the double Michael reaction between methyl vinyl ketone
and ethyl alpha-cyanoacetate, as a model reaction, has been investigated. It was found that cationic N,C,N'-type pincer complexes (1a, Y = NMe2; 1b, Y = pz; 1c, Y = pz* =
3,5-dimethylpyrazol-1-yl; 23) were superior to the P,C,P'- and S,C,S¢-pincer complexes (1d, Y = PPh2; 1e, Y = SPh). The nanosize cationic tri-N,C,N Pd'(II) complex 23 was found to have a catalytic activity per catalytic site in the double Michael reaction of the same order of
magnitude as the monopincer analogue 1a (k = 279 x 10-6 s-1 for 1a vs k = 232 x 10-6 s-1 for 23). The combination of the nanosize dimensions, the catalytic activity, and the high thermal and air stability makes these complexes excellent candidates for application in a continuous process in a nanomembrane reactor.</p></div><table style="margin-bottom: 1em" cellpadding="3" class="not_ep_block" border="0"><tr><th valign="top" class="ep_row">Item Type:</th><td valign="top" class="ep_row">Article</td></tr><tr><th valign="top" class="ep_row">Subjects:</th><td valign="top" class="ep_row"><a href="http://eprints.utas.edu.au/view/subjects/259901.html">250000 Chemical Sciences > 259900 Other Chemical Sciences > 259901 Organometallic Chemistry</a></td></tr><tr><th valign="top" class="ep_row">Collections:</th><td valign="top" class="ep_row">UNSPECIFIED</td></tr><tr><th valign="top" class="ep_row">ID Code:</th><td valign="top" class="ep_row">2865</td></tr><tr><th valign="top" class="ep_row">Deposited By:</th><td valign="top" class="ep_row"><span class="ep_name_citation"><span class="person_name">Prof Allan J Canty</span></span></td></tr><tr><th valign="top" class="ep_row">Deposited On:</th><td valign="top" class="ep_row">15 Jan 2008 08:27</td></tr><tr><th valign="top" class="ep_row">Last Modified:</th><td valign="top" class="ep_row">01 Feb 2008 14:51</td></tr><tr><th valign="top" class="ep_row">ePrint Statistics:</th><td valign="top" class="ep_row"><a target="ePrintStats" href="/es/index.php?action=show_detail_eprint;id=2865;">View statistics for this ePrint</a></td></tr></table><p align="right">Repository Staff Only: <a href="http://eprints.utas.edu.au/cgi/users/home?screen=EPrint::View&eprintid=2865">item control page</a></p>
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