Charged behaviour from neutral ligands: Synthesis and properties of N-heterocyclic pseudo-amides

Article abstract of DOI:10.1002/chem.201103319

Deprotonation of the 1-isopropyl-3-(phenylamino)pyridin-1-ium iodide gives the corresponding neutral betaine, which is formalised as a pyridinium-amido ligand when coordinated to a metal. Spectroscopic, structural and theoretical methods have been used to

Full text of DOI:10.1002/chem.201103319

FULL PAPER
DOI: 10.1002/chem.201103319
Charged Behaviour from Neutral Ligands: Synthesis and Properties of N-
Heterocyclic Pseudo-amides
Robert J. Thatcher, David G. Johnson, John M. Slattery,* and Richard E. Douthwaite*[a]
Abstract: Deprotonation of the 1-iso-
propyl-3-(phenylamino)pyridin-1-ium
iodide gives the corresponding neutral
betaine, which is formalised as a pyridi-
nium-amido ligand when coordinated
to a metal. Spectroscopic, structural
and theoretical methods have been
used to investigate the metal–ligand
bonding, ligand dynamics and electron
distribution. Collectively, the data show
that the ligand can be characterised as
a pseudo-amide and is a strong donor
akin to alkyl phosphines and N-hetero-
cyclic carbenes. Furthermore, rotation
and complexes derived from norhar-
man were prepared, which contain an
ꢀ
ꢀ
about both N substituent C N bonds
additional C C bond supporting conju-
occurs, which is in contrast to the two
alternative pyridinium positional iso-
mers that exhibit neutral resonance
structures. For comparison, compounds
gation and the accessibility of a neutral
resonance structure. Notwithstanding
the formal neutral structure, norhar-
man-derived ligands are comparably
strong donors, and have the additional
advantage of exhibiting stability to di-
oxygen and water.
Keywords: aromaticity · coordina-
tion chemistry · ligand design · N li-
gands · nitrogen heterocycles
Introduction
As prototypical s and p donors, amido ligands, [NR2]ꢀ, sup-
port a wide range of metal complex reactivity and are also
ꢀ
key intermediates in bond forming reactions, such as C N
coupling.[1] Containing a formally anionic NIII atom donor,
amido ligands have two lone pairs available for metal–
ligand bonding. Isoelectronic and broadly isostructural with
amido ligands are neutral carbodicarbene compounds for-
mally defined as C0. Examples, such as 1 (Scheme 1) have
been isolated and have challenged our understanding of
carbon chemistry.[2] Derived from coordination of carbenes
or heteroatom moieties to a carbon atom, two filled carbon
based orbitals are available for metal coordination.[3] Both
amido and carbodicarbene compounds can be considered to
possess localized lone pairs on the donor atom.
Scheme 1. Comparison of carbodicarbene and neutral N donor ligands
exhibiting amido-like character.
In comparison, disubstituted, formally neutral N ligands
exhibiting amido-like character can be envisaged, in which
in lieu of a formal negative charge, N atom donation is sup-
ported by conjugation with a substituent (Scheme 1).[4] Con-
sequently p donation by the ligand can be modified to sup-
port coordination and metal complex reactivity.[4,5] For ex-
ample compounds 2 and 3 (Scheme 1) exhibit canonical res-
onance structures, and spectroscopic and X-ray structural
data indicate a contribution to metal–ligand bonding from
the azolium-amido forms 2’ and 3’. In related chemistry, the
N donor ligand 4 exhibits chemistry reflective of an NI
ligand, which incorporates a cyclopropenium substituent.[4a]
Furthermore, a number of ligands incorporating the guani-
dine motif have been developed, in which N atom donation
is supported by conjugation to the amino moieties.[6] Com-
plexes of some of these ligands have been investigated for
a range of applications, including catalysis[7] and biomimetic
chemistry.[8]
[a] R. J. Thatcher, D. G. Johnson, Dr. J. M. Slattery,
Dr. R. E. Douthwaite
Department of Chemistry, University of York
Heslington, York YO10 5DD (UK)
Fax : (+44)1904-322516
E-mail: richard.douthwaite@york.ac.uk
john.slattery@york.ac.uk
The development of formally neutral analogues of amido
ligands, which exhibit variable electron donation, could po-
tentially open up fundamentally different catalytic pathways
by ligand dissociation that are not available to anionic
amido ligands. Catalytic applications of this novel class of li-
gands are, as yet, rare. However, ligand 2 has recently been
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201103319.
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ꢀ
shown to support nickel-mediated catalytic Sn C bond for-
mation, hinting at exciting possibilities for related ligands.[5]
Our motivation was to investigate the synthesis, electronic
distribution, and metal bonding of new examples of neutral
pseudo-amide ligands in order to provide a variety of struc-
tural and electronic variants and a sound theoretical basis
for understanding their chemistry that will be crucial to
their application. In particular, we have investigated a struc-
tural isomer of 2 and 3, represented by the betaine A
(Scheme 1), for which a neutral structure cannot be drawn
and the electronic structure of the heterocyclic system
cannot be satisfactorily explained by a single canonical
form.[9] For additional comparison with A, a parallel study
of the norharman derived structure B (Scheme 1) was also
undertaken. Compounds of class B are known and exhibit
important biological activity,[10] however, the metal–ligand
chemistry has never been examined. Alkali and transition
metal complexes have been prepared to compare their prop-
erties to amido and common neutral ligands, such as phos-
phines and N-heterocyclic carbenes. Empirical data is sup-
ported by theoretical methods to better understand ligand
bonding (particularly in the p system), ligand dynamics, and
metal–ligand bonding.
Results and Discussion
Figure 1. Molecular structure of complexes 7 (top) and 10 (bottom). El-
lipsoids drawn at 50% probability. Hydrogen atoms have been removed
for clarity.[11]
Alkylation of 3-aminophenylpyridine and subsequent anion
exchange gave compound 5 (Scheme 2), which can be de-
protonated with NaH to give 6 (iPrNPh) as a red viscous oil.
Compound 6 is air sensitive and thermally stable to at least
708C in THF, and for convenience was subsequently pre-
pared and used in situ. On being heated to decomposition
rearrangement to 3-(isopropylphenylamino)-pyridine was
not observed. Attempts to prepare the pyridyl N-Me ana-
logue of 6 led to complex reaction mixtures on deprotona-
lation of single crystals of the dimer [LiACHTUGNTNER{NNUG (m-I)ACHTUNRGTEUNNNG ACHTUNGTRENNUNG(thf)}2]
(iPrNPh)
(7) vide infra (Figure 1).[11]
Similarly, the synthesis and deprotonation of 8 gave 9
(iPrNor) as a yellow powder, which is oxygen and water
stable. Deprotonation of the iodide analogue of
8
([iPrNor(H)][I]) with NaH also resulted in salt incorporation
ꢀ
tion, presumably due to the acidity of the N CH3 protons.
analogous to 6, and a THF solvated sodium iodide adduct
Tosylate 5 was required to isolate 6 because deprotonation
of the analogous iodide [iPrNPh(H)][I] with NaH or KH gave
a salt-containing product, which could not be separated.
Alkali metal coordination was confirmed by deprotonation
{(iPrNor)
[NaACHUTNGTRENUNGN AHCTUNRTEGG(NNNU thf)2ACHTGUNTREN(NUNG m-I)}2] (10) was isolated and structurally
characterised by X-ray diffraction (Figure 1). The coordina-
tion of 6 and 9 to alkali metals is in contrast to 2 and 3,
which were isolated cleanly from deprotonation of the re-
spective iodides with NaH, indicative of a greater electro-
static contribution to metal–ligand bonding, and reflect the
importance of the azolium–amido resonance structure in
these compounds. The geometry and coordination number
at the lithium and sodium atoms of 7 and 10, respectively, is
typical for iodide complexes,[12] and the dimeric M2I2 motif
has been observed for neutral monodentate N donors,
where M=Li,[13] but not for M=Na. The known structures
of [iPrNPh(H)][I] with Li[N
ACTHNUGTRENNUG(SiMe3)2] in THF, which led to iso-
ꢀ
exhibit Li N distances from 2.08(1) to 2.15(4) ꢁ, whereas
ꢀ
for complex 7 Li(1) N(1)=2.020(3), which is significantly
shorter and indicative of a stronger bond. In comparison
ꢀ
lithium diphenylamido complexes typically exhibit a Li N
distance of between 1.950(7) and 2.007(5) ꢁ.[14]
Scheme 2. Synthesis routes to ligands 6 and 9. Reagents and conditions
(yields%): a) iPrI, MeCN, 808C, 1 h (91%); AgOTs, CH2Cl2, 258C, 1 h
(99%); b) NaH, THF, 258C, 15 min (95%); c) iPrI, MeCN, 808C, 1 h
(99%); AgOTs, CH2Cl2, 258C, 1 h (62%); d) NaH, THF, 258C, 15 min
(68%); Ts=Tosylate.
Complexes of the class [RhCl(CO)2(L)] have previously
been used to assess neutral ligand donor properties,[15] so
cis-[RhCl(CO)2ACHTNUTRGNENUG 2ACHTUNGTRENNUNG(
(iPrNPh)] (11) and cis-[RhCl(CO) MeNor)]
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Charged Behaviour from Neutral Ligands
FULL PAPER
(12) were synthesized by addition of [Rh(CO)2Cl]2 to 6
(2 equiv) and MeNor, respectively. The MeNor derivative was
prepared because crystals of the analogous iPrNor complex
could not be grown.
With respect to the metal–ligand bonding and donor
ꢀ
properties of 6 and 9, the trans C O distances and n(CO)
ꢀ
IR stretches of [RhCl(CO)2(L)] Rh N distances for the
complexes incorporating iPrNPh (11), MeNor (12) and 2 are
In order to gauge the contribution of the azolium–amido
resonance structure across the series 2, 3, and 6 the metrical
data of 7, 11, [iPrNPh(H)][I] (see the Supporting Information)
and analogous compounds of 2 and 3,[4b,c] can be compared.
The data indicate that the azolium–amido form is more sig-
nificant for 6 and its derivatives than for 2 and 3. For exam-
2.100(3), 2.0791(11), and 2.096(5) ꢁ, respectively, and the
ꢀ
corresponding trans C O distances are 1.144(5), 1.1343(18),
and 1.128(7) ꢁ.[17] Collectively, comparison of the structural
features of complexes, where L=iPrNPh and 2, show reduced
asymmetry in the N(1) C bond lengths for iPrNPh and
ꢀ
ꢀ
a longer C O bond, which are reflective of increased dona-
ple, the N(1) C(2) bond lengths are consistently longer for
tion. The two n(CO) stretches for L=iPrNPh, MeNor and 2 are
1994, 2068; 1996, 2071; and 1998, 2077 cmꢀ1, respectively,
suggesting that iPrNPh and MeNor have comparable donor
properties, but that these ligands are significantly stronger
donors than 2.
ꢀ
6-derived compounds and complexes, including 1.365(5) for
11, compared to 1.324(7) ꢁ for the analogous complex of 2,
and 1.3719(17) and 1.328(7) ꢁ for [iPrNPh(H)][I] and the
analogous derivative of 3, respectively.[4c] However, there is
ꢀ
significant asymmetry between the N-substituent N C
DFT methods were used to compare the donor strength
of the ligands reported here by using the method recently
proposed by Gusev, which correlates d(CO) and n(CO) in
complexes of the class CpIr(CO)L.[18] Comparison between
phosphines, N-heterocyclic carbenes (NHC), and ligands
from this study (Figure 3) support the spectroscopic and
structural data that indicate 6 and 9 exhibit greater donor
strength than 2, 3, and common examples of phosphines and
ꢀ
ꢀ
bonds, where for 7 N(1) C(2) and N(1) C(9) are 1.339(2)
and 1.411(1), respectively, and for 11, 1.365(5) and
1.422(5) ꢁ. The analogous distances for 10 and 12 are
1.366(3) and 1.373(3) for 10, and 1.3798(17) and
1.3846(17) ꢁ for 12, respectively. In comparison, structures
incorporating the diphenylamido ligand [Ph2N]ꢀ exhibit N
C bonds with an average distance of 1.417(30) ꢁ and the
exocyclic C N distance of 3-aminopyridine is 1.384(4) ꢁ.
ꢀ
[16]
ꢀ
ꢀ
NHC (Figure 3). The C F activation reactivity of Ni com-
The geometry about N(1) is essentially planar in both 7 and
11, which is also the case for complexes of [Ph2N]ꢀ
(Figure 2).
plexes of 2 also reflect a greater donor strength of 2 com-
pared to NHC.[4b] Interestingly, the data also show that for 6
the E isomer, as observed for complexes 7 and 11, is a stron-
ger donor than the Z isomer, Dn(E-Z)(CO)=10 cmꢀ1. The ori-
gins of this difference are not entirely clear, but natural res-
onance theory (NRT) calculations do indicate a marginally
greater amido character for the E isomer that is consistent
with increased donor strength (vide infra).
Figure 2. Molecular structures of complexes 11 (top) and 12 (bottom). El-
lipsoids drawn at 50% probability. Hydrogen atoms have been removed
for clarity.[11]
Figure 3. Plot of d(CO) and n(CO) for DFT optimized structures of vari-
ous ligands (PBE0/def2-TZVPP level). Stronger donors appear top left
and weaker donors bottom right.
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R. E. Douthwaite, J. M. Slattery et al.
Ligand dynamics can play a critical role in defining the
available volume for reactivity at a metal atom, including
aryl amido ligands,[19] which are structurally similar to 6. For
ꢀ
6 and the structural isomers 2 and 3, rotation about the N
C bonds of the coordinating nitrogen atom are key parame-
ters. From structural data it is clear that for 2 and 3 the
ꢀ
N(1) C(2) bond distance is more typical of an imine double
2
bond (1.28 ꢁ) than
a
single
C
R
(sp3) bond
ꢀ
(1.416 ꢁ).[20] Furthermore, for 3 all related protonated and
metal complex derivatives exhibit only the E isomer, and
isomerisation is not observed in the NMR timescale.[4c] In
contrast the molecular structures of [iPrNPh(H)][I] and relat-
ed derivatives (see the Supporting Information) show E, Z
ꢀ
or both isomers, indicating that rotation about the C N
bond of 6 can occur. Indeed, 1H NMR spectroscopy of 6
showed that the protons on C(3) and C(1) exhibit NOEs
with the protons on C(10) and C(14) (see the Supporting In-
formation). In addition, variable temperature studies be-
tween 310–210 K showed only one set of signals with tem-
perature dependent chemical shifts. The structural and
NMR spectroscopy data indicate that in contrast to ligands
Figure 4. HOMO and N(s) lone pair orbitals for 6 (left) and 9 (right; ge-
ometries optimized at the (RI-)MP2/def2TZVPP level).
better understand the origins of the different dynamic and
donor properties exhibited by the four ligands. Compounds
2 and 3 are dominated by the imine resonance structure and
ꢀ
ꢀ
2 and 3, rotation occurs about the N(1) C(2) bond in 6.
the NRT bond orders for the N(1) C(2) bonds are 1.7023
DFT calculations (at the (RI-)PBE0/def2-TZVPP level
using the TURBOMOLE package; see the Supporting In-
formation for all computational details)[21] were performed
to examine the dynamic properties of 6 and the protonated
and 1.8406, respectively, suggesting significant double bond
character, particularly in the case of 2. However, for 6 and 9
azolium–amido structures are the most heavily weighted res-
onance forms (Figure 5).
cation ([iPrNPh(H)]+). The
E
and Z isomers of
6
and
The decreased imine character in 6 and 9 (compared to 2
and 3) are reflected in the NRT bond orders for the N(1)
[iPrNPh(H)]+ are essentially isoenergetic at this level of
theory (see the Supporting Information). Additional calcula-
tions at the (RI-)MP2/def2-TZVPP level give similar results.
ꢀ
C(2) bond of the E and Z isomers of 6 (1.4844 and 1.4824,
respectively) and 9 at 1.3931. These bond orders, which
demonstrate an increasing amido character in the series 9>
6>3>2, are consistent with the increasing donor strength
observed experimentally and in CpIr(CO)L calculations.
ꢀ
The transition state for rotation about N(1) C(2) in
¼
¼
[
iPrNPh(H)]+ is at DG =39 kJmolꢀ1, whereas for 6, DG =
56 kJmolꢀ1 indicative of increased multiple bond character
between N(1) and C(2) in the free base.
In addition to donor strength and dynamics, the electron
distribution in ligands 2, 3, 6 and 9, and frontier molecular
orbitals are clearly important with respect to their character-
istics as ligands. Of relevance, the N donor atom of com-
pound 4 has been formulated as NI, on the basis of DFT
studies and bridging coordination across a PdCl2 dimer.[4a]
The concept of aromaticity has also been discussed at
length, particularly in the context of heterocyclic chemis-
try.[22]
The HOMO and N(s) lone pair orbitals of 2, 3, 6, and 9
(Figure 4 and the Supporting Information) are similar to
those of 4, and like 4 show orbital coefficients significantly
localised on the donor N atom and are distinct from an
imine. However, while the N lone-pair orbital coefficients
are localised in a similar way to 4, the energies of these orbi-
tals for 2, 3, 6 and 9 are likely to be rather different to 4, as
reflected in the propensity of 4 to coordinate to two transi-
tion metals and the much lower n(CO)=1979, 2055 cmꢀ1 of
[RhCl(CO)2(4)] commensurate with NI.[4a]
Figure 5. Selected key structures from the NRT analysis of 6 (left) and 9
(right). NRT weightings are given below each structure, indicating its rel-
ative contribution to the overall hybrid. Where indicated by dashed
bonds the NRT weightings for all aromatic resonance forms of the same
basic structure have been combined.
The relative contributions of different resonance forms to
the electronic structures of 2, 3, 6 and 9 has been probed by
using natural bond orbital (NBO) and NRT calculations[23]
(see the Supporting Information for details) in order to
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Charged Behaviour from Neutral Ligands
FULL PAPER
ed from SiMe4, and are consecutively reported as position (dH or dC), rel-
ative integral, multiplicity (s=singlet, d=doublet, t=triplet, q=quartet,
m=multiplet, br=broad, sep=septet), coupling constant (J in Hz) and
assignment. Assignments of the resonances are supported by 2D experi-
ments. Proton NMR spectra were referenced to the chemical shift of re-
sidual proton signals. Carbon NMR spectra were referenced to a 13C res-
onance of the solvent 1H,1H COSY, 13C HSQC and gradient HMBC ex-
periments were performed by using standard Bruker or Jeol pulse se-
quences. Mass spectra were recorded on a Bruker microToF spectrome-
ter and LIFDI measurements were performed on Bruker Agilent series
1200 LC (Waters Micromass GCT Premier) orthogonal time of flight in-
strument. Major fragments are given as percentages of the base-peak in-
tensity (100%). Elemental analyses were performed at the University of
North London and the University of York.
The NRT weightings for the resonance forms shown in
Figure 5 also demonstrate the significant amide character to
the overall hybrid in 6 and 9. Imine forms are also important
(as demonstrated by significant NRT weightings and NRT
bond orders greater than unity), but the imine contributions
in 6 and 9 are significantly reduced compared to structures
such as 2. In the NRT calculations the N lone-pair “bond
orders”, which relate to the sum of the number of nitrogen
lone pairs in each resonance form multiplied by the reso-
nance weighting for that form, may be interpreted as relat-
ing to a combination of the N(s) and N(p) lone-pair elec-
tron densities, of 2, 3, (E)-6, (Z)-6 and 9 (1.1076, 1.2619,
1.3916, 1.3857 and 1.4452 electrons, respectively) and also
correlate well with the calculated donor strengths described
above. In order to make a comparison with related amido li-
N-phenylpyridin-3-amine: An ampoule charged with 3-bromopyridine
(6.32 g, 40 mmol), aniline (4.47 g, 48 mmol), potassium hydroxide (3.14 g,
56 mmol), water (20 mL), Pd2dba3 (366 mg, 0.4 mmol) and XPhos
(381 mg, 0.8 mmol) was purged with nitrogen for 20 min, then heated at
1108C for 5 h. The reaction mixture was extracted with Et2O (4ꢂ50 mL)
and the collected organic fractions filtered through Celite. The solution
was then reduced to 10 mL under reduced pressure and the subsequent
precipitate was collected by filtration and dried in vacuo to give N-phe-
nylpyridin-3-amine as a beige solid, which was used without further pu-
rification (yield 4.21 g, 62%). 1H NMR (400 MHz, CDCl3, 298 K): d=
5.80 (s, 1H; NH), 6.90–6.96 (m, 1H; HPh), 6.99–7.04 (m, 2H; HPh), 7.10
(dd, JH-H =8, 5 Hz, 1H; H4), 7.20–7.26 (m, 2H; HPh), 7.35 (ddd, JH-H =8,
gands, an NRT analysis was also performed on the amide
ꢀ
ꢀ
anion [Ph2N] . The NRT bond orders for the N C bonds
(1.2965) and the N lone-pair bond order (1.3839) show a re-
ꢀ
duced N C bond order compared to 2, 3, 6 and 9 (as would
be expected), but suggest a remarkably similar N lone-pair
electron density to 6 and 9, supporting the proposal that
these ligands can be viewed as neutral amido analogues.[24]
3, 1 Hz, 1H; H3), 8.09 (dd, JH-H =5, 1 Hz, 1H; H5), 8.29 ppm (d, JH-H
=
3 Hz, 1H; H1); 13C NMR (100 MHz, CDCl3, 298 K): d=118.5 (CPh),
122.2 (CPh), 123.6 (C3), 123.9 (C4), 129.7 (CPh), 140.0 (C1), 140.2 (CPh),
141.9 (C5), 142.0 ppm (C2); MS (ESI): m/z (%): 171.0921 (100) [M+H]+;
elemental analysis calcd (%) for C11H10N2 (170.21): C 77.62, H 5.92, N
16.46; found C 77.50, H 5.95, N 16.41.
Conclusion
In conclusion, the simple N donor ligands (Scheme 1) de-
rived from a N-heterocycle and an exocyclic N donor all ex-
hibit significantly increased donor strength relative to
imines. Considering the synthetic observations, and spectro-
scopic and structural data, 2 and 3 are distinct from their
isomer 6 and related structure 9. An increased contribution
from the azolium–amido form is exhibited for 6 and 9, even
though 9 has a formal neutral resonance structure. Coordi-
nation to alkali metals suggests that 6 and 9, contain a great-
er electrostatic contribution to the metal–ligand bonding.
Furthermore, for compound 6, rotation about the azolium–
ACTHNGUTRNENUG[
iPrNPh(H)][I]: A solution of N-phenylpyridin-3-amine (1.16 g, 6.8 mmol)
in CH3CN (10 mL) was treated with isopropyl iodide (1 mL) and heated
at 808C for 16 h in a sealed ampoule. The volatiles were removed under
reduced pressure to about 1 mL and Et2O (20 mL) added to give
a yellow precipitate that was collected by filtration and was washed with
Et2O (2ꢂ10 mL) and subsequently dried under reduced pressure to give
[
iPrNPh(H)][I] as
1H NMR (400 MHz, CDCl3, 298 K): d=1.72 (d, JH-H =7 Hz, 6H; CH-
a free flowing yellow powder (yield 2.11 g, 91%).
ACHUTNERGNUN(G CH3)2), 4.88 (sep, JH-H =7 Hz, 1H; CHHCAUTGNTERN(NUGN CH3)2), 7.15 (tt, JH-H =7, 2 Hz,
1H; HPh), 7.29–7.38 (m, 4H; HPh), 7.59 (dd, JH-H =9, 6 Hz, 1H; H4), 7.95
(dd, JH-H =9, 2 Hz, 1H; H3), 8.10 (d, JH-H =6 Hz, 1H; H5), 9.24 (s, 1H;
NH), 9.48 ppm (t, JH-H =2 Hz, 1H; H1); 13C NMR (100 MHz, CDCl3,
298 K): d=23.5 (CH3), 65.4 (CHACHTUNGTRNEUNG(CH3)2), 122.0 (CPh), 125.4 (CPh), 125.6
ꢀ
amido C N bond should provide some steric control of
(C3), 128.1 (C4), 129.1 (C1), 129.2 (C5), 130.0 (CPh), 138.3 (CPh), 146.8 ppm
(C2); MS (ESI): m/z (%) 213.1390 (100) [MꢀI]+; elemental analysis
calcd (%) for C14H17N2I (340.21): C 49.43, H 5.04, N 8.23; found C 49.70,
H 5.00, N 8.21.
metal reactivity in complexes of these compounds, similar to
bulky amido ligands. However, the solid state structure of 7
and 11 supported by calculations suggest that in metal com-
plexes the E isomer is about 8 kJmolꢀ1 more stable than the
Z isomer, indicating additional weak metal–ligand interac-
tions. The reactivity and catalytic application of metal com-
plexes incorporating 6 and 9 are currently under investiga-
tion.
Compound 5: A solution of [iPrNPh(H)][I] (389 mg, 1.14 mmol) in CH2Cl2
(4 mL) was treated with silver(I) tosylate (319 mg, 1.14 mmol) in one por-
tion and the reaction mixture was stirred in the dark for 1 h. The reaction
mixture was filtered through Celite and the volatiles were removed
under reduced pressure to give 5 as a viscous yellow oil (yield 435 mg,
99%). 1H NMR (400 MHz, CDCl3, 298 K): d=1.65 (d, JH-H =7 Hz, 6H;
CH3), 2.32 (s, 3H; Ar-CH3), 4.90 (sep, JH-H =7 Hz, 1H; CHACHTNUGTRNEUNG(CH3))2, 7.07–
7.16 (m, 3H; HAr), 7.21 (dd, JH-H =9, 1 Hz, 2H; HAr), 7.31 (t, JH-H =8 Hz,
2H; HAr), 7.48 (dd, JH-H =9, 6 Hz, 1H; H4), 7.80–7.86 (m, 3H; H3), 7.90
(d, JH-H =6 Hz, 1H; H5), 9.35 (t, JH-H =2 Hz, 1H; H2), 9.80 ppm (s, 1H;
NH); 13C NMR (100 MHz, CDCl3, 298 K): d=21.4 (CH3), 23.2 (CH3),
Experimental Section
65.3 (CHACHTUNGTRNEUNG
(CH3)2), 121.7 (CPh), 124.3 (C3), 124.9 (CPh), 126.1 (CAr), 127.9
General: All manipulations were performed under argon by using stan-
dard Schlenk techniques unless stated otherwise. All solvents were dried
over the appropriate drying agent and distilled under argon according to
literature methods. Reagents were purchased from Sigma–Aldrich, Acros
(C4), 128.2 (C5), 128.8 (CPh), 129.8 (CPh), 131.9 (C1), 139.0 (CPh), 139.6
(CPh), 143.5 (CPh), 147.0 ppm (C2); MS (ESI): m/z (%): 213.1446 (100)
[MꢀC7H7O3S]+, 597.2897(20) [M
(C7H7O3S)]+; elemental analysis calcd
2ACHTUNGTRENNUNG
(%) for C21H24N2O3S (384.50): C 65.60, H 6.29, N 7.29; found C 64.19, H
6.33, N 7.00.
[25]
or Lancaster and used as supplied. [Rh(CO)2Cl]2 was prepared accord-
ing to the literature procedure. NMR spectra were recorded at the probe
temperature on JEOL 400, Bruker AV-500 and Bruker AMX-700 instru-
ments. Chemical shifts are described in parts per million, downfield shift-
Compound 6: A solution of 5 (50 mg, 0.13 mmol) in [D8]THF (0.7 mL)
was treated with NaH (4 mg, 0.15 mmol) in one portion and stirred for
Chem. Eur. J. 2012, 18, 4329 – 4336
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
4333

R. E. Douthwaite, J. M. Slattery et al.
10 min. The reaction mixture was filtered through Celite into an NMR
139.8 (CAr), 143.4 (CAr), 144.8 (CAr); elemental analysis calcd (%) for
C21H22N2SO3 (382.48): C 65.95, H 5.80 N, 7.32; found C 64.86, H 5.73, N
6.95.
tube. 1H NMR (700 MHz, [D8]THF, 298 K): d=1.47 (d, JH-H =7 Hz, 6H;
CH3), 4.24 (sep, JH-H =7 Hz, 1H; CHACHTUNGTRNE(UNG CH3)2), 6.58 (t, JH-H =7 Hz, 1H;
HPh), 6.63 (dd, JH-H =5, 1 Hz, 1H; H5), 6.73 (dd, JH-H =9, 5 Hz, 1H; H4),
6.80 (d, JH-H =7 Hz, 2H; HPh), 6.93 (dd, JH-H =9, 2 Hz, 1H; H3), 7.04 (t,
Compound 9: A THF (2 mL) suspension of NaH (15 mg, 0.63 mmol) was
added to a slurry of 8 (200 mg, 0.52 mmol) in THF (15 mL) and the reac-
tion mixture was stirred at 208C for 16 h. The reaction mixture was fil-
tered through Celite and volatiles were removed under reduced pressure
until about 5 mL solution remained. Pentane (20 mL) was added and the
solution was cooled to ꢀ108C for 2 h to give 9 as a yellow precipitate.
Compound 9 was collected by filtration and residual volatiles were re-
moved under reduced pressure to give 9 as a yellow powder (yield 63 mg,
58%). 1H NMR (500 MHz, [D8]THF, 298 K): d=1.69 (d, JH-H =6 Hz,
J
H-H =8 Hz, 2H; HPh), 7.36 ppm (s, 1H; H1); 13C NMR (176 MHz,
[D8]THF, 298 K): d=22.8 (CH3), 63.1 (CHACHTNUTRGNEUNG
(CH3)2), 113.8 (C5), 119.0
(CPh), 121.6 (CPh), 123.5 (C3), 127.1 (C4), 129.4 (CPh), 130.6 (C1), 155.0
(C2), 156.0 ppm (CPh).
Complex 7: A slurry of [iPrNPh(H)][I] (1.0 g, 2.9 mmol) in THF (20 mL)
was treated with lithium bis(trimethylsilylamide) (590 mg, 3.5 mmol) in
one portion at 208C to immediately give a deep-red mixture. The mixture
was stirred for 30 min, then pentane (100 mL) was added and the mixture
was stored at ꢀ208C, overnight. The supernatant was decanted to give an
oily residue, which was washed with pentane (2ꢂ100 mL) and subse-
quently allowed to dry under an inert atmosphere to give 7 as a free-
flowing dark-red powder (yield 735 mg, 63%). 1H NMR (700 MHz,
[D8]THF, 298 K): d=1.62 (d, JH-H =7 Hz, 6H, CH3), 1.74–1.80 (m; THF),
6H; CH3), 4.87 (sep, JH-H =6 Hz, 1H; CHACHTUNGTRNE(GNU CH3)2), 6.96 (t, JH-H =7 Hz,
1H; HAr), 7.36 (t, JH-H =7 Hz, 1H; HAr), 7.74 (d, JH-H =8 Hz, 1H; HAr),
7.79 (d, JH-H =6 Hz, 1H; H5), 8.12 (d, JH-H =8 Hz, 1H; HAr), 8.17 (d,
J
H-H =6 Hz, 1H; H4), 9.14 ppm (s, 1H; H1); 13C NMR (125 MHz,
[D8]THF, 298 K): d=23.6 (CH3), 62.6 (CHACHTNUTRGNEUNG
(CH3)2), 115.5 (C4), 117.2
(CAr), 119.9 (C5), 120.6 (CAr), 122.4 (CAr), 122.6 (CAr), 128.0 (CAr), 130.4
(C1), 133.2 (C3), 147.8 (C2), 160.7 ppm (CAr); IR (KBr): v˜ =3433 (br),
3045 (w), 2973 (w), 2929 (w), 1621 (s), 1479 (s), 1429 (m), 1334 (s), 1308
(m), 1251 (s), 1114 (m), 757 (m), 726 cmꢀ1 (m); elemental analysis calcd
3.58–3.65 (m; THF), 4.57 (sep, JH-H =7 Hz, 1H; CHACHTNUGTRNEUGN(CH3)2), 6.78 (t,
J
H-H =7 Hz, 1H; HAr), 6.85 (dd, JH-H =9, 5 Hz, 1H; H4), 6.89 (d, JH-H
=
7 Hz, 2H; HAr), 6.92 (dd, JH-H =9, 2 Hz, 1H; H3), 7.02 (d, JH-H =4 Hz,
1H; H5), 7.15 (d, JH-H =8 Hz, 2H; HAr), 8.90 ppm (s, 1H; H1); 13C NMR
(%) for C14H14N2ACTHNUGTRNE(UNG H2O)0.25 (214.62): C 78.29, H 6.80, N 13.04; found C
78.09, H 6.63, N 13.06.
(176 MHz, [D8]THF, 298 K): d=23.2 (CH3), 63.8 (CH
(CH3)2), 117.1 (C5),
121.1 (CPh), 122.4 (C3), 124.3 (CPh), 127.1 (C4), 129.9 (CPh), 133.0 (C1),
Complex 10: A THF (2 mL) solution of NaH (8 mg, 0.33 mmol) was
added to a slurry of [iPrNor(H)][I] (100 mg, 0.30 mmol) in THF (4 mL)
and the reaction mixture was stirred at 208C for 20 h. The resulting solu-
tion was filtered through Celite, hexane (10 mL) was added and the solu-
tion was cooled at ꢀ208C for 16 h to give 10 as red crystals. Complex 10
was isolated by filtration and residual volatiles were removed under re-
duced pressure to give 10 as an orange powder (yield 75 mg, 69%).
155.3 (CPh), 157.4 ppm (C2).
ACHTUNGTRENNUNG[
MeNor(H)][I]: A solution of norharman (1.00 g, 6 mmol) in CH3CN
(20 mL) was treated with methyl iodide (1 mL) in one portion and stirred
at 208C for 16 h. The precipitate was collected by filtration and a second
crop was obtained by evaporation of the filtrate to about 5 mL and addi-
tion of Et2O (10 mL). The combined solids were washed with Et2O
(5 mL) and dried under reduced pressure to give
[
MeNor(H)][I] as
1H NMR (400 MHz, [D8]THF, 298 K): d=1.72–1.79 (m, 6H; CH
THF), 3.52–3.58 (m; THF), 4.85 (sep, JH-H =7 Hz, 1H; CH(CH3)2), 6.98
(t, JH-H =7 Hz, 1H; HAr), 7.36 (ddd, JH-H =8, 7, 1 Hz, 1H; HAr), 7.72 (d,
ACHTUNGTRENNUNG(CH3)2 +
a white solid (yield 1.77 g, 96%). 1H NMR (400 MHz, D2O, 298 K): d=
4.33 (s, 3H; CH3), 7.37 (t, JH-H =8 Hz, 1H; HAr), 7.55 (d, JH-H =8 Hz, 1H;
ACHTUNGTRENNUNG
H
Ar), 7.73 (t, JH-H =8 Hz, 1H; HAr), 8.05 (d, JH-H =8 Hz, 1H; HAr), 8.13
J =
H-H =8 Hz, 1H; HAr), 7.87 (dd, JH-H =6, 1 Hz, 1H; H5), 8.12 (d, JH-H
(d, JH-H =6 Hz, 1H; H5), 8.21 (d, JH-H =6 Hz, 1H; H4), 8.65 ppm (s, 1H;
H1); 13C NiMR (100 MHz, D2O, 298 K): d=47.6 (CH3), 112.5 (CAr), 117.1
(C4), 118.7 (Cq), 121.6 (CAr), 122.7 (CAr), 128.8 (C1), 131.9 (CAr), 132.2
(C3), 132.6 (C5), 134.6 (C2), 143.6 ppm (CAr); elemental analysis calcd
(%) for C12H11N2I (310.128): C 46.47, H 3.58, N 9.03; found C 46.43, H
3.64, N 9.13.
8 Hz, 1H; HAr), 8.18 (d, JH-H =6 Hz, 1H; H4), 10.17 ppm (d, JH-H =1 Hz,
1H; H1); 13C NMR (100 MHz, [D8]THF, 298 K): d=23.8 (CH3), 63.3
(CHACHTNUTGRNEUNG
(CH3)2), 115.7 (C4), 117.7 (CAr), 119.6 (CAr), 121.9 (C5), 122.3 (C1)
122.8 (CAr), 128.6 (CAr), 131.9 (CAr), 133.5 (C3), 147.6 (C2), 159.6 ppm
(CAr), THF peaks are coincident; MS (LIFDI): m/z (%) 211.1242 (100)
[
iPrNor(H)]+; elemental analysis calcd (%) for C14H14N2NaI·
ACHTUNGTRENNUNG(C4H8O)0.7
ACHTUNGTRENNUNG[
iPrNor(H)][I]: This was prepared in an analogous manner to [MeNor(H)]
(410.65): C 49.14, H 4.81, N 6.82; found C 49.16, H 4.81, N 6.84.
[I] by using norharman (200 mg), isopropyl iodide (1 mL) and CH3CN
Complex 11: NaH (4 mg, 0.15 mmol) was added in one portion to a solu-
tion of 5 (50 mg, 0.13 mmol) in [D8]THF (0.7 mL) and stirred for 15 min.
The reaction mixture was filtered through Celite and was added in one
portion to solid [Rh(CO)2Cl]2 (25 mg, 0.06 mmol) and the reaction mix-
ture was stirred for a further 30 min and NMR spectroscopy data were
obtained. An aliquot of the solution was used to obtain MS data. Vola-
tiles were removed under reduced pressure and the solid was extracted
into toluene from which the IR spectra were obtained. Crystals of 11 suit-
able for XRD were grown from a toluene (1 mL) solution layered with
hexane (5 mL) at ꢀ208C over 12 h, which decomposed at ꢀ208C over
(10 mL; yield 418 mg, 99%). 1H NMR (400 MHz, CDCl3, 298 K): d=
1.82 (d, JH-H =7 Hz, 6H; CH
ACHTUNGNERT(UNNG CH3)2), 5.02 (sep, JH-H =7 Hz, 1H; CH-
ACHTUNGTRENNUNG(CH3)2), 7.43 (ddd, JH-H =8, 7, 1 Hz, 1H; Ar-H), 7.76 (ddd, JH-H =8, 7,
1 Hz, 1H; Ar-H), 7.86 (dt, JH-H =8, 1 Hz, 1H; Ar-H), 8.21 (dt, JH-H =8,
1 Hz, 1H; Ar-H), 8.26 (dd, JH-H =7, 1 Hz, 1H; H5), 8.40 (d, JH-H =7 Hz,
1H; H4), 10.19 (d, JH-H =1 Hz, 1H; H1), 12.25 ppm (brs, 1H; NH);
13C NMR (100 MHz, CDCl3, 298 K): d=24.0 (CH3), 64.8 (CH
ACTHNUGTRNEUGN(CH3)2),
114.0 (CAr), 117.6 (C4), 119.1 (CAr), 122.5 (CAr), 122.8 (CAr), 128.1 (C1),
128.2 (C5), 132.9 (CAr), 133.5 (C3), 136.1 (C2), 144.5 ppm (CAr); elemental
analysis calcd (%) for C14H15N2I (338.19): C 49.72, H 4.47, N 8.28; found
C 49.39, H 4.70, N 8.59.
several days. 1H NMR (700 MHz, [D8]THF, 298 K): d=1.57 (d, JH-H
=
=
7 Hz, 6H; CH3), 4.60 (sep, JH-H =7 Hz, 1H; CHACHTUNRGTNEN(UG CH3)2), 7.00 (t, JH-H
7 Hz, 1H; H4), 7.11 (dd, JH-H =9, 6 Hz, 1H, H5), 7.23–7.29 (m, 4H; HPh),
7.34 (dd, JH-H =9, 2 Hz, 1H; H3), 7.42 (d, JH-H =5 Hz, 1H; H5), 8.29 ppm
(s, 1H; H1); 13C NMR (176 MHz, [D8]THF, 298 K): d=23.0 (CH3), 64.4
Compound 8: A solution of [iPrNor(H)][I] (500 mg, 1.48 mmol) in CH2Cl2
(25 mL) was treated with silver tosylate (413 mg, 1.48 mmol) in one por-
tion and stirred in the dark for 1 h. The reaction mixture was filtered
through Celite and the filter cake was washed with CH2Cl2 (25 mL). The
filtrates were combined and the volatiles were removed under reduced
pressure to give 8 as a fluffy beige solid (yield 352 mg 62%). 1H NMR
(400 MHz, CDCl3, 298 K): d=1.68 (d, JH-H =7 Hz, 6H; CH3), 2.30 (s,
(CHACHTNUTGRNEUNG
(CH3)2), 121.9 (C5), 124.2 (CPh), 126.7 (C4 +CPh), 128.0 (C3), 130.0
(CPh), 131.5 (C1), 152.3 (CPh), 157.3 (C2), 181.4 (d, JRh-C =77 Hz, CO),
185.7 ppm (d, JRh-C =63 Hz, CO); MS (FD): m/z (%) 213.1304 (100)
[C14H16N2]+, 405.9971 (85) [M]+, 583.1482 (25) [MꢀCl+C14H16N2]+,
619.1341 (25) [M+C14H16N2]+; IR (Tol): v˜ =2068 (s), 1994 cmꢀ1 (s).
3H; CH3), 4.93 (sep, JH-H =7 Hz, 1H; CHACHTUNGTRNE(GNU CH3)2), 7.15 (d, JH-H =8 Hz,
2H; HTosyl), 7.32 (dd, JH-H =7, 1 Hz, 1H; HAr), 7.65 (td, JH-H =8, 1 Hz,
1H; HAr), 7.69 (d, JH-H =8 Hz, 1H; HAr), 7.91 (d, JH-H =8 Hz, 2H; HTosyl),
8.09 (d, JH-H =8 Hz, 1H; HAr), 8.29 (d, JH-H =6 Hz, 1H; H4), 8.39 (d,
Complex 12: A MeCN (1 mL) solution of [Rh(CO)2Cl]2 (20 mg,
0.05 mmol) was added to a solution of MeNor (19 mg, 0.1 mmol) in
CH3CN (2 mL) and stirred for 12 h at 208C. The volatiles were removed
under reduced pressure and the sample was washed with hexane (5 mL)
to give 12 as a yellow powder (yield 34 mg, 87%). 1H NMR (700 MHz,
[D8]THF, 298 K): d=4.38 (s, 3H; CH3), 7.18 (ddd, JH-H =8, 7, 1 Hz, 1H;
HAr), 7.59 (ddd, JH-H =8, 7, 1 Hz, 1H; HAr), 7.93 (dd, JH-H =6, 1 Hz, 1H;
J
H-H =6 Hz, 1H; H5), 9.93 (s, 1H; H1), 12.95 ppm (s, 1H; NH); 13C NMR
(100 MHz, CDCl3, 298 K): d=21.4 (CH3), 23.7 (CH3), 64.4 (CHACTHNUTRGNEUNG(CH3)2),
113.7 (CAr), 117.5 (C4), 119.3 (CAr), 121.8 (CAr), 122.8 (CAr), 126.1 (CAr),
128.2 (C1), 128.9 (CAr), 129.3 (C5), 132.2 (CAr), 132.9 (C3), 136.5 (C2),
4334
www.chemeurj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2012, 18, 4329 – 4336

Charged Behaviour from Neutral Ligands
FULL PAPER
H5), 8.04 (d, JH-H =8 Hz, 1H; HAr), 8.18 (d, JH-H =8 Hz, 1H; HAr), 8.29 (d,
J
Acknowledgements
H-H =6 Hz, 1H; H4), 9.26 ppm (s, 1H; H1); 13C NMR (700 MHz,
[D8]THF, 298 K): d=47.4 (CH3), 116.4 (C4), 119.1 (CAr), 122.1 (CAr),
122.8 (CAr), 127.7 (C5), 130.4 (CAr), 134.1 (C3), 134.3 (C1), 144.9 (C2),
156.3 (CAr), 182.7 (d, JRh-C =75 Hz, CO), 186.7 ppm (d, JRh-C =68 Hz,
CO); MS (FD): m/z (%) 183 (25) [C12H10N2 +H]+, 376 (100) [M]+, 523
(60) [MꢀCl+C12H10N2]+; elemental analysis calcd (%) for
C14H10O2N2RhCl (376.59): C 44.65, H 2.67, N 7.44; found C 44.73, H
2.60, N 7.36; IR (Tol): v˜ =2071 (s), 1996 cmꢀ1 (s).
The authors are grateful to Dr. Adrian Whitwood and Dr. David Wil-
liamson at the University of York for crystallographic and NMR spec-
troscopy assistance, respectively, and to Prof. Frank Weinhold, University
of Wisconsin, for many useful discussions regarding NRT analysis. We
also thank the University of York and the EPSRC (Grant GR/H011455/
1) for financial support.
Crystallographic studies: Diffraction data for compounds 11 and 12 were
collected at 110 K on a Bruker Smart Apex diffractometer with MoKa ra-
diation (l=0.71073 ꢁ) by using a SMART CCD camera. Diffractometer
control, data collection and initial unit cell determination was performed
by using “SMART”. Frame integration and unit-cell refinement software
was carried out with “SAINT+”. Absorption corrections were applied
by SADABS (v.2.10, Sheldrick). Structures were solved by either Patter-
son or direct methods by using SHELXS-97 and refined by full-matrix
least squares by using SHELXL-97.[26] Diffraction data for compounds 7
and 10, were collected at 110 K on Agilent SuperNova diffractomer with
MoKa radiation (l=0.71073 ꢁ). Data collection, unit-cell determination
and frame integration were carried out with “CrysalisPro”. Absorption
corrections were applied by using crystal face-indexing and the AB-
SPACK absorption correction software within CrysalisPro. Structures
were solved and refined by using Olex2[27] implementing SHELX algo-
rithms. Structures were solved by either Patterson or direct methods by
using SHELXS-97 and refined by full-matrix least squares with
SHELXL-97.[26] All non-hydrogen atoms were refined anisotropically.
Carbon bound hydrogen atoms were placed by using a “riding model”
and included in the refinement at calculated positions or otherwise found
by difference map.
[1] M. Lappert, A. Protchenko, P. Power, A. Seeber, Metal Amide
Chemistry, Wiley–Blackwell, New York, 2008.
[2] a) F. Ramirez, B. Hansen, N. B. Desai, N. McKelvie, J. Am. Chem.
Soc. 1961, 83, 3539–3540; b) C. A. Dyker, V. Lavallo, B. Donnadieu,
G. Bertrand, Angew. Chem. 2008, 120, 3250–3253; Angew. Chem.
Int. Ed. 2008, 47, 3206–3209; c) M. Alcarazo, C. W. Lehmann, A.
Anoop, W. Thiel, A. Furstner, Nat. Chem. 2009, 1, 295–301; d) A.
Fꢃrstner, M. Alcarazo, R. Goddard, C. W. Lehmann, Angew. Chem.
2008, 120, 3254–3258; Angew. Chem. Int. Ed. 2008, 47, 3210–3214.
[3] a) R. Tonner, F. Oexler, B. Neumuller, W. Petz, G. Frenking, Angew.
Chem. 2006, 118, 8206–8211; Angew. Chem. Int. Ed. 2006, 45, 8038–
8042; b) R. Tonner, G. Frenking, Chem. Eur. J. 2008, 14, 3273–3289;
c) R. Tonner, G. Frenking, Chem. Eur. J. 2008, 14, 3260–3272; d) A.
Dyker, G. Bertrand, Nat. Chem. 2009, 1, 265–266.
[4] a) H. Bruns, M. Patil, J. Carreras, A. Vazquez, W. Thiel, R. God-
dard, M. Alcarazo, Angew. Chem. 2010, 122, 3762–3766; Angew.
Chem. Int. Ed. 2010, 49, 3680–3683; b) M. E. Doster, S. A. Johnson,
Angew. Chem. 2009, 121, 2219–2221; Angew. Chem. Int. Ed. 2009,
48, 2185–2187; c) Q. Shi, R. J. Thatcher, J. Slattery, P. S. Sauari,
A. C. Whitwood, P. C. McGowan, R. E. Douthwaite, Chem. Eur. J.
2009, 15, 11346–11360.
Crystal data for 7: Red crystals of 7 were grown from slow diffusion of
pentane into a tetrahydrofuran solution. 2(C18H24ILiN2O), Mr =836.46,
a=9.7185(6), b=10.4073(6), c=11.3012(7) ꢁ, a=104.125(5), b=
102.712(5), g=116.614(6)8, V=916.73(9) ꢁ3, T=110.0 K, triclinic, space
[5] M. E. Doster, J. A. Hatnean, T. Jeftic, S. Modi, S. A. Johnson, J. Am.
Chem. Soc. 2010, 132, 11923–11925.
[6] a) M. P. Coles, Chem. Commun. 2009, 3659–3676; b) N. Kuhn, R.
Fawzi, M. Steimann, J. Wiethoff, Z. Anorg. Allg. Chem. 1997, 623,
769–774; c) S. Pohl, M. Harmjanz, J. Schneider, W. Saak, G.
Henkel, J. Chem. Soc. Dalton Trans. 2000, 3473–3479; d) D. Petrov-
ic, T. Bannenberg, S. Randoll, P. G. Jones, M. Tamm, Dalton Trans.
2007, 2812–2822; e) H. Wittmann, V. Raab, A. Schorm, J. Plack-
meyer, J. Sundermeyer, Eur. J. Inorg. Chem. 2001, 1937–1948.
[7] a) S. H. Li, Y. J. Lin, J. G. Cao, S. B. Zhang, J. Org. Chem. 2007, 72,
4067–4072; b) T. K. Panda, C. G. Hrib, P. G. Jones, J. Jenter, P. W.
Roesky, M. Tamm, Eur. J. Inorg. Chem. 2008, 4270–4279; c) S. Ran-
doll, P. G. Jones, M. Tamm, Organometallics 2008, 27, 3232–3239;
d) S. D. Bunge, J. M. Lance, J. A. Bertke, Organometallics 2007, 26,
6320–6328; e) J. Bçrner, U. Florke, K. Huber, A. Doring, D. Kuck-
ling, S. Herres-Pawlis, Chem. Eur. J. 2009, 15, 2362–2376.
¯
group P1, Z=1, 22218 reflections measured, 4529 independent reflec-
tions (Rint =0.0327). The final R1 values were 0.0194 [I>2s(I)]. The final
wR(F2) values were 0.0412 [I>2s(I)]. The final R1 values were 0.0229
(all data). The final wR(F2) values were 0.0427 (all data).
Crystal data for 10: Yellow crystals of 10 were obtained from layering
pentane over a THF solution of 10. One THF ligand was modelled as dis-
ordered over two positions in 74:26 ratio. 0.5(C44H60I2N4Na2O4), Mr =
504.37, a=13.7670(5), b=8.6019(6), c=19.2732(4) ꢁ, a=90.00, b=
95.634(3), g=90.008, V=2271.37(18) ꢁ3, T=110.0 K, monoclinic, space
group P21/n, Z=4, 12341 reflections measured, 6351 independent reflec-
tions (Rint =0.0282). The final R1 values were 0.0319 [I>2s(I)]. The final
wR(F2) values were 0.0627 [I>2s(I)]. The final R1 values were 0.0431
(all data). The final wR(F2) values were 0.0692 (all data).
[8] a) M. Schatz, V. Raab, S. P. Foxon, G. Brehm, S. Schneider, M.
Reiher, M. C. Holthausen, J. Sundermeyer, S. Schindler, Angew.
Chem. 2004, 116, 4460–4464; Angew. Chem. Int. Ed. 2004, 43, 4360–
4363; b) S. Herres-Pawlis, U. Florke, G. Henkel, Eur. J. Inorg. Chem.
2005, 3815–3824; c) S. Herres-Pawlis, P. Verma, R. Haase, P. Kang,
C. T. Lyons, E. C. Wasinger, U. Florke, G. Henkel, T. D. P. Stack, J.
Am. Chem. Soc. 2009, 131, 1154–1169; d) D. Maiti, D. H. Lee, K.
Gaoutchenova, C. Wurtele, M. C. Holthausen, A. A. N. Sarjeant, J.
Sundermeyer, S. Schindler, K. D. Karlin, Angew. Chem. 2008, 120,
88–91; Angew. Chem. Int. Ed. 2008, 47, 82–85; e) J. England, M.
Martinho, E. R. Farquhar, J. R. Frisch, E. L. Bominaar, E. Munck,
L. Que, Angew. Chem. 2009, 121, 3676–3680; Angew. Chem. Int.
Ed. 2009, 48, 3622–3626.
Crystal data for 11: Yellow crystals of 11 were grown from layering
hexane over a toluene solution of 11. C16H16ClN2O2Rh, Mr =406.67,
monoACHTUNGTRENNUNGclinic, a=13.328(11), b=8.840(8), c=14.813(12) ꢁ, a=90.00, b=
98.504(16), g=90.008, V=1726(3) ꢁ3, T=110(2) K, monoclinic, space
group P21/n, Z=4, 12687 reflections measured, 3018 independent reflec-
tions (Rint =0.0628). The final R1 values were 0.0391 [I>2s(I)]. The final
wR(F2) values were 0.0934 [I>2s(I)]. The final R1 values were 0.0552
(all data). The final wR(F2) values were 0.1013 (all data).
Crystal data for 12: Orange crystals of 12 were obtained from layering
Et2O over
a MeCN solution of 12. Mr =376.60, monoclinic, a=
11.0230(7), b=10.9200(7), c=12.1081(8) ꢁ, a=90.00, b=112.2530(10),
g=90.008, V=1348.91(15) ꢁ3, T=110(2) K, monoclinic, space group
P21/c, Z=4, 14873 reflections measured, 3892 independent reflections
(Rint =0.0189). The final R1 values were 0.0191 [I>2s(I)]. The final
wR(F2) values were 0.0488 [I>2s(I)]. The final R1 values were 0.0205
(all data). The final wR(F2) values were 0.0496 (all data).
[9] A. D. McNaught, A. Wilkinson, IUPAC Compendium of Chemical
Terminology, 2nd ed., Blackwell Scientific, Oxford, 1997.
[10] a) S. Bonazzi, D. Barbaras, L. Patiny, R. Scopelliti, P. Schneider,
S. T. Cole, M. Kaiser, R. Brun, K. Gademann, Bioorg. Med. Chem.
2010, 18, 1464–1476; b) G. Van Baelen, S. Hostyn, L. Dhooghe, P.
Tapolcsanyi, P. Matyus, G. Lemiere, R. Dommisse, M. Kaiser, R.
Brun, P. Cos, Bioorg. Med. Chem. 2009, 17, 7209–7217; c) A. Storch,
Y. I. Hwang, D. A. Gearhart, J. W. Beach, E. J. Neafsey, M. A. Col-
lins, J. Schwarz, J. Neurochem. 2004, 89, 685–694; d) R. Albores,
Chem. Eur. J. 2012, 18, 4329 – 4336
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
4335

R. E. Douthwaite, J. M. Slattery et al.
E. J. Neafsey, G. Drucker, J. Z. Fields, M. A. Collins, Proc. Natl.
Acad. Sci. USA 1990, 87, 9368–9372.
2002, 117, 9535–9538; e) P. Deglmann, F. Furche, R. Ahlrichs,
Chem. Phys. Lett. 2002, 362, 511–518; f) P. Deglmann, K. May, F.
Furche, R. Ahlrichs, RI-J implementation 2004, 384, 103–107; g) K.
Eichkorn, O. Treutler, H. Oehm, M. Haeser, R. Ahlrichs, Chem.
Phys. Lett. 1995, 240, 283–289; h) K. Eichkorn, F. Weigend, O.
[11] CCDC 838594 (7), 838595 (10), 838596 (11), 838597 (12), 838685
[
iPrN(H)Ph][I], 838686 iPrN(H)iPr][I], 838687 iPrN(H)Cy][I], and
[ [
838688
[
iPrNor(H)][I] contain the supplementary crystallographic
data for this paper. These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via www.ccdc.cam.a-
c.uk/data_request/cif
TreutACTHGNUTERNNUlG er, R. Ahlrichs, Theo. Chem. Acc. 1997, 97, 119–124; i) T.
Koga, H. Kobayashi, J. Chem. Phys. 1985, 82, 1437–1439; j) P. Pulay,
Chem. Phys. Lett. 1980, 73, 393–398; k) O. Treutler, R. Ahlrichs, J.
Chem. Phys. 1995, 102, 346–354; l) F. Weigend, Phys. Chem. Chem.
Phys. 2006, 8, 1057–1065.
[12] F. H. Allen, Acta Crystallogr. B 2002, 58, 380–388.
[13] a) C. L. Raston, W. T. Robinson, B. W. Skelton, C. R. Whitaker,
A. H. White, Aust. J. Chem. 1990, 43, 1163–1173; b) C. L. Raston,
C. R. Whitaker, A. H. White, J. Chem. Soc. Dalton Trans. 1988,
991–995.
[14] a) U. Braun, T. Habereder, H. Noth, H. Piotrowski, M. Warchhold,
Eur. J. Inorg. Chem. 2002, 1132–1145; b) R. A. Bartlett, H. V. R.
Dias, H. Hope, B. D. Murray, M. M. Olmstead, P. P. Power, J. Am.
Chem. Soc. 1986, 108, 6921–6926.
[15] a) A. Fꢃrstner, M. Alcarazo, H. Krause, C. W. Lehmann, J. Am.
Chem. Soc. 2007, 129, 12676–12677; b) A. R. Chianese, X. W. Li,
M. C. Janzen, J. W. Faller, R. H. Crabtree, Organometallics 2003, 22,
1663–1667; c) W. A. Herrmann, J. Schutz, G. D. Frey, E. Herdtweck,
Organometallics 2006, 25, 2437–2448.
[16] M. Chao, E. Schempp, R. D. Rosenstein, Acta Crystallogr. Sect. B:
Struct. Sci. 1975, 31, 2924–2926.
[17] Average values have been calculated for the complex incorporating
2 because the asymmetric unit contains two molecules.
[18] D. G. Gusev, Organometallics 2009, 28, 763–770.
[19] C. E. Laplaza, M. J. A. Johnson, J. C. Peters, A. L. Odom, E. Kim,
C. C. Cummins, G. N. George, I. J. Pickering, J. Am. Chem. Soc.
1996, 118, 8623–8638.
[20] F. H. Allen, O. Kennard, D. G. Watson, L. Brammer, A. G. Orpen,
R. Taylor, J. Chem. Soc. Perkin. Trans. 2 1987, S1–S19.
[21] a) R. Ahlrichs, M. Baer, M. Haeser, H. Horn, C. Koelmel, Chem.
Phys. Lett. 1989, 162, 165–169; b) M. von Arnim, R. Ahlrichs, J.
Chem. Phys. 1999, 111, 9183–9190; c) P. Csꢄszꢄr, P. Pulay, J. Mol.
Struct. 1984, 114, 31–34; d) P. Deglmann, F. Furche, J. Chem. Phys.
[22] A. T. Balaban, D. C. Oniciu, A. R. Katritzky, Chem. Rev. 2004, 104,
2777–2812.
[23] a) E. D. Glendening, J. K. Badenhoop, A. E. Reed, J. E. Carpenter,
J. A. Bohmann, C. M. Morales, F. Weinhold, University of Wiscon-
sin, Madison, 2001; b) E. D. Glendening, F. Weinhold, J. Comput.
Chem. 1998, 19, 593–609; c) E. D. Glendening, F. Weinhold, J.
Comput. Chem. 1998, 19, 610–627; d) E. D. Glendening, F. Wein-
hold, J. Comput. Chem. 1998, 19, 628–646; e) A. E. Reed, L. A.
Curtiss, F. Weinhold, Chem. Rev. 1988, 88, 899–926; f) G. W. T. M. J.
Frisch, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman,
J. A. Montgomery, Jr., T. Vreven, K. N. Kudin, J. C. Burant, J. M.
Millam, S. S. Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi,
G. Scalmani, N. Rega, G. A. Petersson, H. Nakatsuji, M. Hada,
et al., Revision A.1 ed., Gaussian, Inc., Wallingford CT, 2004.
[24] Due to the symmetry of [Ph2N]ꢀ a different set of primary reference
structures to 1, 2, 5 and 7 was used in the NRT analysis.
[25] M. Montag, L. Schwartsburd, R. Cohen, G. Leitus, Y. Ben-David,
J. M. Martin, D. Milstein, Angew. Chem. 2007, 119, 1933–1936;
Angew. Chem. Int. Ed. 2007, 46, 1901–1904.
[26] G. Sheldrick, Acta Crystallogr. Sect. A 2008, 64, 112–122.
[27] O. V. Dolomanov, L. J. Bourhis, R. J. Gildea, J. A. K. Howard, H.
Puschmann, J. Appl. Crystallogr. 2009, 42, 339–341.
Received: October 20, 2011
Published online: February 29, 2012
4336
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