(e) M. Konkol and J. Okuda, Coord. Chem. Rev., 2008, 252,
1577–1591; (f) J. Cheng, K. Saliu, M. J. Ferguson, R. McDonald
and J. Takats, J. Organomet. Chem., 2010, 695, 2696–2702;
(g) A. A. Trifonov, Coord. Chem. Rev., 2010, 254, 1327–1347;
(h) M. Nishiura and Z. Hou, Nat. Chem., 2010, 2, 257–268.
3 For examples of Cp-ligated rare-earth polyhydride complexes, see:
(a) O. Tardif, M. Nishiura and Z. Hou, Organometallics, 2003, 22,
1171–1173; (b) K. C. Hultzsch, P. Voth, T. P. Spaniol and
J. Okuda, Z. Anorg. Allg. Chem., 2003, 629, 1272–1276;
(c) D. Cui, O. Tardif and Z. Hou, J. Am. Chem. Soc., 2004, 126,
1312–1313; (d) O. Tardif, D. Hashizume and Z. Hou, J. Am. Chem.
Soc., 2004, 126, 8080–8081; (e) D. Cui, M. Nishiura and Z. Hou,
Angew. Chem., Int. Ed., 2005, 44, 959–962; (f) D. Cui, M. Nishiura
and Z. Hou, Macromolecules, 2005, 38, 4089–4095; (g) Y. Luo,
J. Baldamus, O. Tardif and Z. Hou, Organometallics, 2005, 24,
4362–4366; (h) T. Shima and Z. Hou, J. Am. Chem. Soc., 2006, 128,
8124–8125; (i) M. Yousufuddin, M. J. Gutimann, J. Baldamus,
O. Tardif, Z. Hou, S. A. Mason, G. J. McIntyre and R. Bau,
J. Am. Chem. Soc., 2008, 130, 3888–3891; (j) Y. Takenaka,
T. Shima, J. Baldamus and Z. Hou, Angew. Chem., Int. Ed.,
2009, 48, 7888–7891; (k) T. Shima and Z. Hou, Dalton Trans.,
2010, 39(29), 6858–6863; (l) T. Stewart, M. Nishiura, Y. Konno,
Z. Hou, G. J. McIntyre and R. Bau, Inorg. Chim. Acta, 2010, 363,
562–566; (m) M. Nishiura, J. Baldamus, T. Shima, K. Mori and
Z. Hou, Chem.–Eur. J., 2011, 17, 5033–5044; (n) T. Shima,
M. Nishiura and Z. Hou, Organometallics, 2011, 30, 2513–2524;
(o) T. Shima, Y. Luo, T. Stewart, R. Bau, G. J. McIntyre,
S. A. Mason and Z. Hou, Nat. Chem., 2011, 3, 814–820.
Fig. 3 ORTEP plot of the cationic part of 5-Lu (left) and dicationic part
of 6-Lu (right) with thermal ellipsoids at the 30% probability level.
Hydrogen atoms, except that bonding to the formadinate moiety, and
i
the Pr groups in the amidinate ligands have been omitted for clarity.
Selected bond distances [A] for 5-Lu: Lu1–N1 2.291(7), Lu1–N2 2.268(7),
Lu1–N3 2.300(7), Lu1–N4 2.304(7), Lu1–O1 2.336(5), Lu1–O2 2.266(6),
C1–H1 1.10(8); for 6-Lu: Lu1–N1 2.275(5), Lu1–N2 2.297(5),
Lu1–O1 2.249(4), Lu1–O2 2.278(4), Lu1–O3 2.291(4), Lu1–O4 2.248(4).
(av. 2.267 A) bond lengths in 6-Lu are, respectively, slightly
shorter than those in 3-Lu (Lu–N: av. 2.297 A; Lu–O: av.
2.291 A), probably owing to the more electropositive metal
center of the dicationic complex 6-Lu.
4 For examples of non-Cp-ligated rare-earth polyhydride complexes,
see: (a) M. Ohashi, M. Konkol, I. Del Rosal, R. Poteau, L. Maron
and J. Okuda, J. Am. Chem. Soc., 2008, 130, 6920–6921;
(b) J. Cheng, K. Saliu, G. Y. Kiel, M. J. Ferguson,
R. McDonald and J. Takats, Angew. Chem., Int. Ed., 2008, 47,
4910–4913; (c) J. Cheng, M. J. Ferguson and J. Takats, J. Am.
Chem. Soc., 2010, 132, 2–3; (d) D. M. Lyubov, C. Doring,
G. K. Fukin, A. V. Cherkasov, A. S. Shavyrin, R. Kempe and
A. A. Trifonov, Organometallics, 2008, 27, 2905–2907. See also
ref. 5b.
5 (a) X. Li, J. Baldamus, M. Nishiura, O. Tardif and Z. Hou, Angew.
Chem., Int. Ed., 2006, 45, 8184–8188; (b) J. Cheng, T. Shima and
Z. Hou, Angew. Chem., Int. Ed., 2011, 50, 1857–1860;
(c) D. M. Lyubov, C. Doring, S. Y. Ketkov, R. Kempe and
A. A. Trifonov, Chem.–Eur. J., 2011, 17, 3824–3826.
6 (a) X. Li, M. Nishiura, K. Mori, T. Mashiko and Z. Hou, Chem.
Commun., 2007, 4137–4139; (b) N. Yu, M. Nishiura, X. Li, Z. Xi
and Z. Hou, Chem.–Asian J., 2008, 3, 1406–1414; (c) X. Li,
M. Nishiura, L. Hu, K. Mori and Z. Hou, J. Am. Chem. Soc.,
2009, 131, 13870–13882; (d) L. Zhang, T. Suzuki, Y. Luo,
M. Nishiura and Z. Hou, Angew. Chem., Int. Ed., 2007, 46,
1909–1913.
7 (a) S. Bambirra, M. W. Bouwkamp, A. Meetsma and B. Hessen,
J. Am. Chem. Soc., 2004, 126, 9182–9183; (b) S. Bambirra, D. van
Leusen, A. Meetsma, B. Hessen and J. H. Teuben, Chem. Commun.,
2003, 522–523.
In summary, the highly elusive cationic terminal hydrido
rare earth species such as 3-Lu has been isolated and structurally
characterized for the first time by the use of an amidinate group
as an ancillary ligand. Recrystallization of the monocationic
monohydride complexes 3-Ln in a less coordinative solvent
such as chlorobenzene has afforded reversibly the novel dicationic
binuclear dihydride complexes 4-Ln through release of a THF
ligand and ‘‘intermolecular’’ Ln–H bonding interactions. The
insertion of a carbodiimide molecule into the Ln–H bond in
3-Lu yields the corresponding cationic formamidinate species
5-Lu. On reaction with [NEt3H][BPh4], dehydrogenation of
3-Lu takes place to give the hydride-free dicationic complex
6-Lu. Studies on the influences of ancillary ligands on the
structure and reactivity of the cationic rare earth hydride
complexes are in progress.
The authors thank Mrs Akiko Karube for micro elemental
analyses. This work was partly supported by a Grant-in-Aid
for Scientific Research (S) (No. 21225004) from the Ministry
of Education, Culture, Sports, Science and Technology of
Japan and the Key Project of International Cooperation of
NSFC (20920102030). J.C. is grateful to RIKEN for a FPR
fellowship award.
8 For neutral mononuclear rare earth hydride complexes bearing
two sterically demanding cyclopentadienyl ligands, see:
(a) Y. Takenaka and Z. Hou, Organometallics, 2009, 28,
5196–5203; (b) L. Maron, E. L. Werkema, L. Perrin,
O. Eisenstein and R. A. Andersen, J. Am. Chem. Soc., 2005, 127,
279–292; (c) K. H. Denhaan, Y. Wielstra and J. H. Teuben,
Organometallics, 1987, 6, 2053–2060; (d) J. Gavenonis and
T. D. Tilley, J. Organomet. Chem., 2004, 689, 870–878.
Notes and references
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10 Generally, the JY–H coupling constant becomes smaller in higher
1
degrees (m2-, m3-, m4-, etc.) of bridging bonds. See: ref. 2f and 3n.
c
816 Chem. Commun., 2012, 48, 814–816
This journal is The Royal Society of Chemistry 2012