Journal of Inorganic and General Chemistry
ARTICLE
Zeitschrift für anorganische und allgemeine Chemie
[2] A. J. Arduengo III, R. L. Harlow, M. Kline, J. Am. Chem. Soc.
presume that the lower activity of the NHI systems mainly
1991, 113, 361.
derives from the decreased conformational flexibility of the
planar four-membered Al2N2 cycle in comparison to the less
rigid six-membered ring in Roesky’s 1,3-diketiminato alumi-
num complexes rather than from steric congestion of the cen-
tral metal atom. For the 1,3-diketiminato complexes the per-
petual increase and decrease of the metal atom’s coordination
number, which is typical for the substrate association and
dissociation processes involved in catalytic conversions, may
require less costs of energy for conformational adaptation of
the ligand scaffold. Furthermore, we cannot rule out a negative
cooperativity between the two catalytically active sites in 1
and 2, respectively, that is substrate binding to one metal center
of the dimer may hamper substrate conversion at the adjacent
aluminum site.
[3] a) J. C. Y. Lin, R. T. W. Huang, C. S. Lee, A. Bhattacharyya,
W. S. Hwang, I. J. B. Lin, Chem. Rev. 2009, 109, 3561; b) S.
Díez-González, N. Marion, S. P. Nolan, Chem. Rev. 2009, 109,
3612; c) K. Riener, S. Haslinger, A. Raba, M. P. Högerl, M. Co-
koja, W. A. Herrmann, F. E. Kühn, Chem. Rev. 2014, 114, 5215.
[4] a) L. J. Murphy, K. N. Robertson, J. D. Masuda, J. A. C. Cly-
burne, in N-Heterocyclic Carbenes: Effective Tools for Organo-
metallic Synthesis (Ed.: S. P. Nolan), Wiley-VCH, Weinheim,
2014, pp. 427–497; b) P. de Frémont, N. Marion, S. P. Nolan,
Coord. Chem. Rev. 2009, 253, 862; c) Y. Wang, G. H. Robinson,
Inorg. Chem. 2011, 50, 12326; d) S. Bellemin-Laponnaz, S. Da-
gorne, Chem. Rev. 2014, 114, 8747; e) N. M. Hopkinson, C. Rich-
ter, M. Schedler, F. Glorius, Nature 2014, 510, 485.
[5] H. Braunschweig, R. D. Dewhurst, K. Hammond, J. Mies, K. Ra-
dacki, A. Vargas, Science 2012, 336, 1420.
[6] a) Y. Wang, Y. Xie, P. Wei, R. B. King, H. F. Schaefer III, P.
von R. Schleyer, G. H. Robinson, Science 2008, 321, 1069; b) Y.
Xiong, S. Yao, S. Inoue, J. D. Epping, M. Driess, Angew. Chem.
2013, 125, 7287; Angew. Chem. Int. Ed. 2013, 52, 7147.
[7] a) A. Sidiropoulos, C. Jones, A. Stasch, S. Klein, G. Frenking,
Angew. Chem. 2009, 121, 9881; Angew. Chem. Int. Ed. 2009, 48,
9701; b) Y. Xiong, S. Yao, G. Tan, S. Inoue, M. Driess, J. Am.
Chem. Soc. 2013, 135, 5004.
[8] a) N. Kuhn, H. Bohnen, J. Kreutzberg, D. Bläser, R. Boese, J.
Chem. Soc., Chem. Commun. 1993, 1136; b) S. Kronig, P. G.
Jones, M. Tamm, Eur. J. Inorg. Chem. 2013, 2301; c) K. Powers,
C. Hering-Junghans, R. McDonald, M. J. Ferguson, E. Rivard,
Polyhedron 2016, 108, 8; d) R. D. Crocker, T. V. Nguyen, Chem.
Eur. J. 2016, 22, 2208.
[9] a) N. Kuhn, M. Göhner, M. Grathwohl, J. Wiethoff, G. Frenking,
Y. Chen, Z. Anorg. Allg. Chem. 2003, 629, 793; b) A. G. Tram-
bitas, T. K. Panda, M. Tamm, Z. Anorg. Allg. Chem. 2010, 636,
2156; c) X. Wu, M. Tamm, Coord. Chem. Rev. 2014, 260, 116;
d) T. Ochiai, D. Franz, S. Inoue, Chem. Soc. Rev. 2016, DOI:
10.1039/C6CS00163G.
[10] a) C. Cui, H. W. Roesky, H. Hao, H.-G. Schmidt, M. Noltemeyer,
Angew. Chem. 2000, 112, 1885; Angew. Chem. Int. Ed. 2000, 39,
1815; b) V. Jancik, Y. Peng, H. W. Roesky, J. Li, D. Neculai,
A. M. Neculai, R. Herbst-Irmer, J. Am. Chem. Soc. 2003, 125,
1452; c) S. González-Gallardo, V. Jancik, R. Cea-Olivares, R. A.
Toscano, M. Moya-Cabrera, Angew. Chem. 2007, 119, 2953; An-
gew. Chem. Int. Ed. 2007, 46, 2895; d) D. Franz, S. Inoue, Chem.
Eur. J. 2014, 20, 10645.
Conclusions
The implementation of main group metal complexes in ca-
talysis is in its infancy. In this contribution, we studied the
catalytic hydroboration of terminal arylalkynes and carbonyl
compounds (e.g. aldehydes, ketones) with pinacolborane using
dimeric NHI-stabilized aluminum dihydrides (1) or aluminum
hydride triflates (2). The hydroboration of alkynes proceeds
faster if the π system is rich in electron density and steric
hindrance of the catalyst reduces conversion rates. In contrast,
the hydroboration of carbonyl compounds is less prone to the
electronic and steric properties of the substrates and the cata-
lyst.
Future investigations will focus on the use of cationic alumi-
num hydrides in catalysis and expansion of the catalytic scope
of hydrometallations toward other unsaturated functional
groups (e.g. imines, nitriles, thioketones).
Experimental Section
In a typical catalytic experiment an NMR sample tube was charged
with the catalyst (1 or 2, 4 mol%), the substrate (alkyne or carbonyl
compound, 1 equiv.), pinacolborane (1 equiv.) and C6D6 (0.5 mL) in a
Glove Box Workstation. The sample tube was flame-sealed at the
Schlenk line and stored at 80 °C (alkyne reactions) or closed with a
rubber cap supported by PTFE-coated tape and stored at room tem-
perature in a Glove Box Workstation (carbonyl reactions). The pro-
[11] a) X. Ma, Z. Yang, X. Wang, H. W. Roesky, F. Wu, H. Zhu, Inorg.
Chem. 2011, 50, 2010; b) L. A. Berben, Chem. Eur. J. 2015, 21,
2734; c) Z. Yang, M. Zhong, X. Ma, K. Nijesh, S. De, P. Parames-
waran, H. W. Roesky, J. Am. Chem. Soc. 2016, 138, 2548; d) Z.
Yang, Y. Yi, M. Zhong, S. De, T. Mondal, D. Koley, X. Ma, D.
Zhang, H. W. Roesky, Chem. Eur. J. 2016, 22, 6932.
[12] a) D. Neculai, H. W. Roesky, A. M. Neculai, J. Magull, B. Wal-
fort, D. Stalke, Angew. Chem. 2002, 114, 4470; Angew. Chem.
Int. Ed. 2002, 41, 4294; b) D. Franz, T. Szilvási, E. Irran, S.
Inoue, Nat. Commun. 2015, 6, 10037; c) D. Franz, S. Inoue, Dal-
ton Trans. 2016, 45, 9385.
1
gress of the reaction was monitored by H NMR spectroscopy.
Supporting Information (see footnote on the first page of this article):
further details of the experiments.
[13] Z. Yang, M. Zhong, X. Ma, S. De, C. Anusha, P. Parameswaran,
H. W. Roesky, Angew. Chem. 2015, 127, 10363; Angew. Chem.
Int. Ed. 2015, 54, 10225.
Acknowledgements
[14] For transition metal-catalyzed hydroborations of alkenes and alk-
ynes see: a) D. Männig, H. Nöth, Angew. Chem. 1985, 97, 854;
Angew. Chem. Int. Ed. Engl. 1985, 24, 878; b) K. Burgess, M. J.
Ohlmeyer, Chem. Rev. 1991, 91, 1179; c) I. Beletskaya, A. Pelter,
Tetrahedron 1997, 53, 4957; d) C. M. Crudden, D. Edwards, Eur.
J. Org. Chem. 2003, 4695; e) M. Haberberger, S. Enthaler, Chem.
Asian J. 2013, 8, 50; f) L. Zhang, Z. Zuo, X. Leng, Z. Huang,
Angew. Chem. 2014, 126, 2734; Angew. Chem. Int. Ed. 2014, 53,
2696; g) M. Espinal-Viguri, C. R. Woof, R. L. Webster, Chem.
Eur. J. 2016, 22, 11605.
We are grateful to the WACKER Chemie AG, as well as the European
Research Council (SILION 637394) for financial support.
References
[1] a) H.-W. Wanzlick, H.-J. Schönherr, Angew. Chem. 1968, 80, 154;
Angew. Chem. Int. Ed. Engl. 1968, 7, 141; b) K. Öfele, J. Or-
ganomet. Chem. 1968, 12, 42.
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