Download Quintuple Bonding

Ultra-Short Metal–Metal Distances and
Extreme Bond Orders*
Universität Bayreuth
* F. Wagner, A. Noor, R. Kempe, Nature Chem. 2009, 1, 529.
Introduction
The nature of the chemical bond and in particular metal-metal bonds has always been a fascinating field for scientists and in particular for chemists. Metal-metal bond orders higher than four in stable
compounds have been recently extended to five. In this context of shortest metal-metal bond and extreme bond orders, the element chromium has played a decisive role. The initial reactivity studies of
such quintuply bonded species not only indicate their potential to access new structure and bonding situations but might also be a stimulating factor for future investigations.
Comparison of Ligand Size
The Ap for Cp concept Ap =Aminopyridinates
1
Quintuple Bonding and the Shortest Metal-Metal Bonds
2
M
3
R1
R2
R1
N
O
M
M
b
b
a
a
N
Cr
Cr
N
N
R
M
N
N
M'
M
N
R
Reviews: R. Kempe, Eur. J. Inorg. Chem. 2003, 791; R. Kempe, H.
Noss, T. Irrgang, J. Organomet. Chem. 2002, 647, 12; R. Kempe,
a = b = 5.8 Å Cp*
N
a = 15.5 Å
b = 8.5Å
Ap*
Cr-Cr 1.835 Ǻ
Concept: X-Y-Z Ligands Hein Cotton Principe
Ap Chromium Chemistry
Y
M
M
Z
X
Y
N
Z
N
H
1
a) KH
b) [CrCl3(thf)3]
a) BuLi
b) CrCl2
N
Cr N
Mes
TIP
N Mes
N
thf
Cr
TIP
thf
N
N
N
Cr
Cl
N
N
Cr
Cr
N
N
Cr
N
Cl
Cr
N
thf
N
thf TIP
N
Cl 3 Cl
A Quintuple Bond of 1.75 Å
K. A. Kreisel, G. P. A. Yap, O. Dmitrenko, C. R.
Landis, K. H. Theopold, J. Am. Chem. Soc.
2007, 129, 14162.
Photo Finish for the Shortest Metal-Metal Bond1)
Metal-Metal Bonds: Shorter and Shorter2)
Gold for the Shortest Bond3)
6
5
X
Cr-Cr 1.803 Ǻ
T. Nguyen, A. D. Sutton, S. Brynda, J. C. Fettinger,
G. J. Long, P. P. Power, Science 2005, 310, 844.
N. M. Scott, T. Schareina, O. Tok, R. Kempe, Eur. J. Inorg. Chem. 2004,
3297.
Angew. Chem. Int. Ed. 2000, 39, 468.
4
M
M
N
4
Mes
Cr-Cr 1.74 Ǻ5)
Cr-Cr 1.74 Ǻ4)
KC8
7
1) K. Sanderson, Nature Chem. 2008, doi:10.1038/news.2008.1042.
2) N. Withers, Nature Chem. 2008, doi:10.1038/nchem.54.
KC8
TIP
Cr
Cr
Mes
N
N
Mes
3) J. S. Yeston, Science 2008, 321, 1134.
Cr Cr
5
N
TIP
N
4) Y.-C. Tsai, C.-W. Hsu, J.-S. K. Yu, G.-H. Lee, Y. Wang, T.-S. Kuo, Angew. Chem. Int. Ed. 2008,
47, 7360.
5) A. Noor, F. R. Wagner, R. Kempe, Angew. Chem. Int. Ed. 2008, 47, 7356.
Cr-Cr 1.749 Ǻ
Quintuple Bond Reactivity
9
a) Isosurface diagram of the
pELI-D contributions
Sterically optimized
b) Section plane shows (total)ELI-D and semitransparent
surface shows QTAIMbasin of one of the Cratoms.
N2 O2
Cr1
Cr1-N1 2.053(2),
Cr1-N2 1.946(2),
O1-Cr1 1.563(2),
O2-Cr1 1.791(2),
Cr1-Cr1A 2.5314(10).
N1
N1
N2
N1
O1
O2
Cl1
KC8
Cr1
Cr2
Cr1
O1
N2
The Role of Ligand and its Fine Tuning
I2
N1
8
N2
I1
Cr1-Cr1A 1.75 Å
Cr1
Carboalumination
N
N
N
Me
Cr
Cr
N
AlMe3
Cr Cr
N
Cr1-N1 2.028(9), Cr1-N2 2.004(8),
I1-Cr1 2.752(2), Cr1-Cr1A 1.871 (4).
N
Al
Me2
N
N
Wiberg-bond index
ELF 0.7
isosurface
Al1 Cr1 2.8945(14)
Al1 Cr2 2.9076(14)
Cr1 Cr2 1.8365(8)
Cr Cr 3.5
Cr Me 0.3
Cr Al 0.27
4.4 for quintuple
A. Noor, G. Glatz, R. Müller, M. Kaupp, S. Demeshko, R. Kempe,
Z. Anorg. Allg. Chem. 2009, 635, 1149.
A. Noor, G. Glatz, R. Müller, M. Kaupp, S. Demeshko, R. Kempe, Nature Chem. 2009, 1, 322.
NBO partial-charge
Cr +0.49 to +0.67
Al(CH3)2- and CH3fragments -0.12 and -0.47,
respectively