Inorganic Chemistry
Communication
diffraction indicated that pyr coordination to the V-PPi core
REFERENCES
(1) (a) Centi, G.; Trifiro,
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had occurred, affording {[(VO)bipy(pyr)] (P O )} (2-pyr;
2
2
7
̀
F.; Ebner, J. R.; Franchetti, V. Chem. Rev.
Figure 1c). 2-pyr is structurally very similar to 2, the main
difference being that the pyr molecule in 2-pyr replaces the
equatorial water molecule of 2. Lower activity was noted in the
1988, 88, 55 and references cited therein. For recent literature, see,
for instance: (b) Luciani, S.; Cavani, F.; Dal Santo, V.; Dimitratos, N.;
Rossi, M.; Bianchi, C. L. Catal. Today 2011, 169, 200. (c) Cavani, F.;
Luciani, S.; Degli Esposti, E.; Cortelli, C.; Leanza, R. Chem.Eur. J.
presence of pyr compared to NEt , suggesting that coordination
3
2
(
010, 16, 1646.
of the base to the vanadium center does not promote catalyst
turnover, as is observed for some homogeneous vanadium
2) (a) Johnson, J. W.; Johnston, D. C.; Jacobson, A. J.; Brody, J. F. J.
Am. Chem. Soc. 1984, 106, 8123. (b) Bordes, E.; Courtine, P.; Johnson,
J. W. J. Solid State Chem. 1984, 55, 270. (c) Torardi, C. C.; Li, Z. G.;
Horowitz, H. S.; Liang, W.; Whangbo, M.-H. J. Solid State Chem. 1995,
119, 349. (d) Guliants, V. V.; Holmes, S. A.; Benziger, J. B.; Heaney,
P.; Yates, D.; Wachs, L. E. J. Mol. Catal. A: Chem. 2001, 172, 265.
3) Herron, N.; Thorn, D. I.; Harlow, R. L.; Coulston, G. W. J. Am.
Chem. Soc. 1997, 110, 7149.
4) Solis-Ibarra, D.; Silvia, J. S.; Jancik, V.; Cummins, C. C. Inorg.
Chem. 2011, 50, 9980.
5) (a) Marino, N.; Fazen, C. H.; Blakemore, J. D.; Incarvito, C. D.;
Hazari, N.; Doyle, R. P. Inorg. Chem. 2011, 50, 2507. (b) Marino, N.;
Ikotun, O. F.; Julve, M.; Lloret, F.; Cano, J.; Doyle, R. P. Inorg. Chem.
2011, 50, 378. (c) Marino, N.; Vortherms, A. R.; Hoffman, A. E.;
Doyle, R. P. Inorg. Chem. 2010, 49, 6790. (d) Ikotun, O. F.; Higbee, E.
M.; Ouellette, W.; Doyle, R. P. J. Inorg. Biochem. 2009, 103, 1254.
e) Marino, N.; Mastropietro, T. F.; Armentano, D.; De Munno, G.;
Doyle, R. P.; Lloret, F.; Julve, M. Dalton Trans. 2008, 38, 5152.
f) Ikotun, O. F.; Armatus, N. G.; Julve, M.; Kruger, P. E.; Lloret, F.;
Nieuwenhuyzen, M.; Doyle, R. P. Inorg. Chem. 2007, 46, 6668.
g) Kruger, P. E.; Doyle, R. P.; Julve, M.; Lloret, F.; Niewenhuyzen, M.
1
0a−c
catalysts.
Sanford et al. recently demonstrated that the
addition of pyr could serve to either promote catalysis (as was
initially predicted to happen for 2) or impede it because of
metal coordination site saturation, in a concentration-depend-
1
0d
(
ent manner.
catalyst revealed improved activity with respect to 2 (with 70−
0% conversion observed, on average, with 1 mol % 2-anhydr
Preliminary results using 2-anhydr as the
(
8
and 10 mol % NEt at 100 °C for 72 h), also supporting the
3
(
idea of the free equatorial coordination site being fundamental
for catalysis. This point will be further investigated in future
mechanistic work.
In summary, the initial results that we report herein offer a
rare V-PPi coordination complex with confirmed catalytic
activity under relatively mild conditions possibly proceeding
through an intriguing homogeneous−heterogeneous catalytic
route. We believe this approach offers significant potential as a
platform for future investigations, including fundamental
catalytic mechanistic studies and rational catalyst design for
mild oxidations through V-PPi “cores”. This work prospects a
potential paradigm shift for the VPO field, focusing on a
discrete molecular entity, expanding the perspective from
purely solid-state to coordination chemistry. The two new
structures presented herein are valuable additions to the current
array of metal pyrophosphate coordination complexes and
demonstrate that mild vanadium phosphate chemistry is indeed
possible. The synthesis of further such examples as well as the
study of the reactivity of 2 toward a variety of substrates is
currently underway in our laboratory.
(
(
(
Inorg. Chem. 2001, 40, 1726. (h) Doyle, R. P.; Nieuwenhuyzen, M.;
Kruger, P. E. Dalton Trans. 2005, 23, 3745.
6) Hanson, S. K.; Wu, R.; Silks, L. A. Org. Lett. 2011, 13, 1908.
7) Ikotun, O. F.; Marino, N.; Kruger, P. E.; Julve, M.; Doyle, R. P.
Coord. Chem. Rev. 2010, 254, 890.
(
(
(
(
8) Details are given in the SI.
9) Control experiments carried out under argon and/or in absence
of NEt showed no sample dissolution and no aldehyde production,
3
suggesting that both the base and air (oxygen) are fundamental for
generating the active phase in solution.
(10) (a) Hanson, S. K.; Baker, R. T.; Gordon, J. C.; Scott, B. L.; Silks,
L. A.; Thorn, D. L. J. Am. Chem. Soc. 2010, 132, 17804. (b) Hanson, S.
K.; Baker, R. T.; Gordon, J. C.; Scott, B. L.; Sutton, A. D.; Thorn, D. L.
J. Am. Chem. Soc. 2009, 131, 428. (c) Hanson, S. K.; Baker, R. T.;
Gordon, J. C.; Scott, B. L.; Thorn, D. L. Inorg. Chem. 2010, 49, 5611.
ASSOCIATED CONTENT
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(
d) Emmert, M. H.; Cook, A. K.; Xie, Y. J.; Sanford, M. S. Angew.
Chem., Int. Ed. 2011, 50, 9409.
*
S
Supporting Information
X-ray crystallographic data in CIF format, synthetic procedures,
AUTHOR INFORMATION
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Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
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R.P.D. acknowledges the Office of the Vice President for
Research at Syracuse University for postdoctoral funding to
N.M. and the American Chemical Society for a Doctoral New
Investigator Award (48999-DNI 3). N.M. further acknowledges
the Fondo Sociale Europeo, POR Calabria FSE 2007/2013, for
partial funding. S.K.H. acknowledges Los Alamos National
Laboratory (LDRD20110537ER). P.M. acknowledges the
National Science Foundation for funding provided for the
purchase of X-ray equipments (Grant CHE-0946721).
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dx.doi.org/10.1021/ic3015767 | Inorg. Chem. 2012, 51, 10077−10079