Dynamic behavior of an N-metalated Β-enaminoimine complex - Preparation of N-phosphanylenamine and Β-enaminoimine derivatives

Article abstract of DOI:10.1002/ejic.200390128

Variable-temperature NMR spectroscopy of the β-enaminoimine complex 2 showed a dynamic process which was attributed to an internal fluxional aldimido N-zirconated π-linear/σ-bent structure. Such an internal rearrangement has been previously proposed to occur in these systems but never observed. We have prepared a variety of (N-phosphanyl-β-enamino)imine ligands using the hydrozirconation/transmetalation reaction of malonodinitrile compounds RCH(CN)2 (R = H, PPh₂). In addition to their potential uses in coordination chemistry, these systems are good tools for the study of intramolecular hydrogen bonding. The X-ray crystal structure of 14 at 180 K shows an unsymmetrical system with the N(H) proton localized on one of the two chelating nitrogen atoms, consistent with the existence in solution of a low barrier proton transfer process with a double-well potential. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.

Full text of DOI:10.1002/ejic.200390128

FULL PAPER
Dynamic Behavior of an N-Metalated β-Enaminoimine Complex ؊
Preparation of N-Phosphanylenamine and β-Enaminoimine Derivatives
Alexandrine Maraval,[a] Krzysztof Owsianik,[b] Damien Arquier,[a] Alain Igau,*[a]
Yannick Coppel,[a] Bruno Donnadieu,[a] Maria Zablocka,[b] and Jean-Pierre Majoral*[a]
Keywords: N ligands / NMR spectroscopy / Imines / Zirconium / Metallocenes / Transmetalation
Variable-temperature NMR spectroscopy of the β-enamino- tion chemistry, these systems are good tools for the study of
imine complex 2 showed a dynamic process which was at-
tributed to an internal fluxional aldimido N-zirconated π-lin-
intramolecular hydrogen bonding. The X-ray crystal struc-
ture of 14 at 180 K shows an unsymmetrical system with the
ear/σ-bent structure. Such an internal rearrangement has N(H) proton localized on one of the two chelating nitrogen
been previously proposed to occur in these systems but never
observed. We have prepared a variety of (N-phosphanyl-β-
enamino)imine ligands using the hydrozirconation/trans-
metalation reaction of malonodinitrile compounds RCH(CN)2
atoms, consistent with the existence in solution of a low bar-
rier proton transfer process with a double-well potential.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
(R = H, PPh2). In addition to their potential uses in coordina- Germany, 2003)
Introduction
ine compounds according to a hydrozirconation/trans-
metalation reaction sequence. We also report an X-ray crys-
tal structure of a β-enaminoimine compound containing an
unsymmetrical intramolecular hydrogen bond.
β-Enaminoimine derivatives have been intensively studied
as members of the family of polymethine merocyanines, a
fundamental group of organic dyes with a wide variety of
[1]
uses.
Related compounds of the type A, also called β-
diimine systems, described as ‘‘formal’’ six-membered rings
with a chelating µ2-H proton bridged to the nitrogen atoms,
have been successfully used as ligands in coordination
chemistry.[2]
Dynamic Behavior of the N-Zirconated
β-Enaminoimine Complex 2
Results
The N-metalated β-enaminoimine compound 2 was pre-
pared by the addition of 2 equiv. of 1 to malonodinitrile in
the presence of a catalytic amount of MeI (Scheme 1).[3]
Recently, we described the synthesis of the β-enaminoim-
ine compound 2, with a transition metal fragment bonded
to the nitrogen atoms (A: R1 ϭ R2 ϭ H, R3 ϭ ZrCp2Cl).[3]
In addition to the dynamic NMR behaviour of the N-zir-
conated β-enaminoimine 2, we present herein the prepara-
tion of N-phosphanylenamine derivatives and describe the
formation of unsymmetrical (N-phosphanyl-β-enamino)im-
[a]
Laboratoire de Chimie de Coordination, CNRS,
205 route de Narbonne, 31077 Toulouse Cedex, France
Fax: (internat.) ϩ 33-5/61553003
E-mail: majoral@lcc-toulouse.fr
igau@lcc-toulouse.fr
[b]
Polish Academy of Sciences, Centre of Molecular and
Macromolecular Studies,
Sienkiewicza 112, 90-363 Lodz, Poland
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
Scheme 1. Description of the different conformers of the (N-zir-
cona-β-enamino)imine derivative 2 at 193 K; [Zr] ϭ ZrCp2
960
 2003 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim 1434Ϫ1948/03/0305Ϫ0960 $ 20.00ϩ.50/0 Eur. J. Inorg. Chem. 2003, 960Ϫ968

Dynamic Behavior of an N-Metalated -Enaminoimine Complex
FULL PAPER
1
At 293 K, 1D H and 13C NMR spectra show only one to the aldimine carbon atom CH(2/2Ј). Signals due to the
set of signals for the two CH(2/2Ј)ϪN aldimine groups, in- H(2/2Ј) and H(N) protons of the other conformer accident-
dicative of a process that rapidly interconverts the hydrogen ally overlap (1H at 193 K: δ ϭ 7.34 ppm), and the outer
atoms H(2) and H(2Ј) on the NMR time scale. An excita- lines of the doublets are thus no longer visible. Con-
tion-sculpted singly selective 1D TOCSY (Figure 1)[4] al- sequently, it was not possible to determine the different
lows the assignment of the signal of the H(N) proton coupling constants. The 13C NMR spectrum exhibits a peak
bridged by the two nitrogen atoms of the β-enaminoimine at δ ϭ 158.4 ppm [CH(2/2Ј)ϪN group]. Note that the me-
skeleton at δ ϭ 7.10 ppm.[5]. It was clear from this experi- thine CH(1) group resonances [δ ϭ 4.78 ppm Ϫ broad peak
ment that the H(N) proton was involved in an exchange (1H); δ ϭ 93.7 ppm (13C)] and the Cp signals of I and II
having a rate in the intermediate range on the NMR time cannot be differentiated. The NMR spectroscopic assign-
scale. The NMR spectra exhibit two singlets for the Cp ments have been unambiguously confirmed by 2D NMR
groups at δ ϭ 6.35 and 6.53 ppm (1H NMR, 10 H each) experiments at 193 K (gs-DQFCOSY, gs-HMQC). Note
and δ ϭ 116.6 and 114.5 ppm (13C NMR). Lowering of the that line broadening was observed for the Cp groups, but
temperature from 293 to 193 K leads to a splitting of the no splitting of the signals was detected on decreasing the
H(N) and H(2/2Ј) protons, suggesting the presence of at temperature. Exchange between the two conformers I and
least two conformers (Figure 1).
II was definitively established by 1D GROESY experiments
(Scheme 1, Figure 2).[8]
Figure 2. 1D GROESY of 2 at 193 K (the corresponding symmetric
Lewis structures are omitted for clarity) with selective excitation of
the site indicated by the arrow Ǟ; mixing time ϭ 200 ms; lines
denoted by # are residual signals of the Cp protons; [Zr] ϭ
ZrCp2Cl
The 1D GROESY spectrum obtained on irradiation of
the H(2/2Ј) protons of the conformer with δ ϭ 7.49 ppm
displays an exchange peak with the H(2/2Ј) protons of the
other conformer (δ ϭ 7.34 ppm) and an ROE enhancement
(spatial proximity) with H(1) (Figure 2, a). Irradiation of
the H(N) proton of the conformer with δ ϭ 6.70 ppm gives
only a positive exchange peak with the H(N) protons of
the other conformer (δ ϭ 7.34 ppm) (Figure 2, b). Finally,
Figure 1. 1D selective TOCSY of 2 at variable temperature with
excitation of H(1) (the corresponding symmetric Lewis structures
are omitted for clarity); mixing time ϭ 60 ms; [Zr] ϭ ZrCp2Cl
At 193 K the 1H NMR spectrum of the CH(2/ irradiation of the H(1) protons only gives rise to ROE en-
2Ј)ϪNϪH(N) moiety of one of the two conformers shows hancements with the H(2/2Ј) protons of conformers I and
a doublet of doublets at δ ϭ 7.49 ppm [H(2/2Ј)] and a doub- II (Figure 2, c). The GROESY spectrum obtained on irradi-
let at δ ϭ 6.70 ppm [H(N)], with coupling constants of ation of the signal at δ ϭ 7.34 ppm follows from the experi-
3JH(2/2Ј)-H(1) ϭ 5.5 Hz and JH(2/2Ј)-H(N) ϭ 13.0 Hz. The 13C ments a), b), and c) in Figure 2 and definitively demon-
3
NMR spectrum displays a peak at δ ϭ 157.6 ppm, assigned strated the overlapping H(2/2Ј) and N(H) protons for one
Eur. J. Inorg. Chem. 2003, 960Ϫ968
961

A. Igau, J.-P. Majoral et al.
FULL PAPER
conformer: in addition to an ROE enhancement with H(1), tween the Cp ring hydrogen atoms of the two metal frag-
an exchange peak with the H(2/2Ј) protons (δ ϭ 7.49 ppm) ments and between the Cp ring hydrogen atoms and the
and with the N(H) proton (δ ϭ 6.70 ppm) of the other con-
former is also observed. The chemical shift equivalence of
the H(2) and H(2Ј) protons in I and II is accommodated by
a rapid tautomeric conversion of a and b for I and c and d
for II. From the results of the dynamic NMR spectra, 2
appears to behave as a rather unconventional β-enaminoim-
ine system. At low temperature, it is likely that we have been
able to ‘‘freeze out’’ a dynamic process involving a fluxional
structure from which each form identified is in a fast tauto-
meric equilibrium, namely a and b for I and c and d for II.
hydrogen atom of the HϪCϪN moiety of the β-iminoena-
mine skeleton. Because of these steric constraints, the mag-
nitude of the rotation of the ZrCp2Cl fragments about the
ZrϪN bonds is limited, and therefore only a restricted rota-
tion is observed for 2. In metallocene complexes, restricted
rotation about the bond between a metal ion and a planar
amido/ketimide nitrogen atom is assumed to have a very
low activation barrier; to the best of our knowledge no re-
stricted rotation processes in such complexes has been
‘‘frozen out’’ by variable-temperature NMR experi-
ments.[13,14c]
16-Electron d0 group-4 metallocene complexes of the
type Cp2MRRЈ (M ϭ Ti, Zr, Hf) have one vacant orbital
available for conjugative interaction with lone pairs or π-
systems at adjacent σ-bonded ligands R, RЈ.[15] Even
though Cp2MϪN π-interactions are not maximized in
group-4 amido[13] and ketimide[14] metallocene complexes,
π-overlap between the LUMO of the metal fragment and
the nitrogen lone pair has been commonly observed. Erker
and co-workers have reported that aldimido [RCHϭ
NϪZrCp2Cl] complexes have a substantial ZrϪN π-charac-
ter. This was unambiguously demonstrated by an X-ray
structure analysis of B (R ϭ Ph), which showed a nearly
linear ZrϪNϭCHPh unit (ZrϪNϪC 170.5(5)°].[15a,15b] In
solution, the linear heteroallene-type structural unit in B
(R ϭ Ph) is of high stereochemical persistence and rigidity,
and the geometric isomerization (E)/(Z) could be effected
neither thermally nor photochemically. Moreover, the hy-
drozirconation of nitriles using the Schwartz reagent
[Cp2ZrHCl]n led to the corresponding zirconocene ketimide
complexes with a syn stereochemistry; the metal-bound
chlorine atom and the hydrogen atom of the aldimine func-
tion are positioned syn to the linear ZrϪNϪC moiety.
Discussion
The bis(N-zirconated) β-enaminoimine complex 2 con-
tains the vinamidine moiety NϪCϪCϪCϪN and an N-
metalated alkylideneamido arrangement, two types of sub-
structures which may undergo fluxional processes.
It has been reported that β-enaminoimine derivatives
with NϪCϪCϪCϪN core atoms may exist in three differ-
ent configurations: ‘‘trans-trans’’, ‘‘trans-cis’’, and ‘‘cis-cis"
[Equation (1)]. The tautomeric and conformational equilib-
ria of these products have been found to be substituent-,
solvent-, and temperature-dependent.[9]
(1)
3
In CD2Cl2 at 193 K, the coupling constant of JH(2/2Ј)-H(1)
ϭ 5.5 Hz observed for one of the conformers indicates
the presence of the cis-cis form.[10] At 293 K the time-aver-
3
aged JH(2/2Ј)-H(1) coupling constant of 5.7 Hz implies that
the second conformer exhibits the same cis-cis configura-
tion for the vinamidine moiety. Moreover, the same 13C
NMR chemical shift observed for the CH(1) methine group
indicates that the geometry around this carbon atom is re-
tained in I and II.[11] Finally, the ROE enhancement ob-
served for the H(1) and H(2/2Ј) protons of one of the con-
formers confirms the proximity of these protons. These
NMR spectroscopic data establish conformers I and II as
having a cis-cis configuration. Therefore, the dynamic
NMR behavior observed for the N-zirconated β-enamino-
imine complex 2 does not involve the core atoms of the β-
enaminoimine system; the cis-cis rigidity about the
NϪCϪCϪCϪN skeleton is maintained throughout the ob-
served fluxional process.
Starting from the Lewis structure I for 2 (Scheme 1), two
intramolecular dynamic processes may be proposed to ra-
tionalize the results of the low-temperature NMR spectra :
i) rotation of the ZrCp2Cl fragments about the ZrϪN bond
and/or ii) a fluxional π-linear/σ-bent process involving the
N-metalated alkylideneamido moieties in the plane con-
taining the β-enaminoimine system ϪN(H)Ϫ(CH)2ϪCHϭ
NϪ.
It is likely that, at room temperature, we are observing
the results of the two rapid dynamic processes which in-
volve: i) restricted rotation about the ZrϪN bonds and ii)
the σ-bound (I) and π-bound-like (II) N-zirconated con-
formers of the β-enaminoimine compound 2 (Scheme 1).
Consistent with the studies reported in the literature, the
two sets of Cp resonances observed for 2 at room temper-
ature may be the result of restricted rotation about the
ZrϪN bonds, with a molecular geometry which places the
chlorine atoms of the zirconocene fragments Cp2ZrCl syn
to the hydrogen atom of the HCN subunits. It is reasonable
to propose that lowering of the temperature has the effect
of ‘‘freezing out’’ the N-σ-bent-zirconated β-enaminoimine
form I and linearising the ZrϪNϭC units to form the het-
eroallene system II (Scheme 1).[16] This internal fluxional
N-zirconated π-linear/σ-bent structure [Equation (2)] was
Simple close-contact calculations carried out on complex
2
[12] revealed severe intramolecular nonbonded contacts be- previously proposed to occur in these systems but until now
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Eur. J. Inorg. Chem. 2003, 960Ϫ968

Dynamic Behavior of an N-Metalated -Enaminoimine Complex
FULL PAPER
it has not been observed in coordinatively unsaturated N- of an absorption in the region expected for the CϭN func-
metalated alkylideneamido complexes.
tionality in β-enaminoimine systems [ν(CϵN): 1625 cmϪ1
(7), 1621 cmϪ1 (8)]. The 31P NMR spectra of 7 and 8 dis-
play two singlets at δ ϭ 53.3, 87.1 (7) ppm and 64.8, 89.3
(8) ppm. Signals in both 1H and 13C NMR spectra are con-
sistent with CHϭN aldimine groups [7: δ ϭ 7.62 (1H, over-
lapped) ppm, δ ϭ 156.1, 159.8 (13C) ppm; 8: δ ϭ 7.39, 7.91
(1H) ppm, δ ϭ 150.5, 164.5 (13C) ppm] and the central me-
thine CH fragments [7: δ ϭ 4.87 (1H) and δ ϭ 97.6 (13C)
ppm; 8: δ ϭ 4.89 (1H) and δ ϭ 97.8 (13C) ppm] in the β-
diimine derivatives 7 and 8. The 13C NMR chemical shifts
of the central methine CH fragments and the upfield shift
of the broad NH signal [δ ϭ 5.30 (4), 10.54 (7), 10.84 (8)
(2)
On the basis of variable-temperature 1H NMR experi-
ments, the activation barrier of the observed dynamic pro-
cess attributed to the transition between bent (I) and linear
(II) conformers in 2 has been calculated as ∆G‡ ϭ 13 kcal/
mol.[17]
1
ppm] in the H NMR spectra establish 7 and 8 as having a
cis-cis configuration, with a hydrogen-bonded chelate form
in a β-diimine compound.
Preparation of N-Phosphanylenamine and (N-
Phosphanyl-β-enamino)imine Ligands
It is noteworthy that hydrozirconation of succinonitrile
and glutaronitrile using 1 (1 and 2 equiv.) followed by an
exchange reaction with Ph2PX (X ϭ Cl, Br, CN) led to the
formation of insoluble polymeric products.
Under the same experimental conditions as those used
for CH2(CN)2, the phosphanylmalononitrile 9 undergoes
the same ‘‘one pot’’ mono- and dihydrozirconation/trans-
metalation reaction sequence(Scheme 3). Addition of 1
equiv. of 1 to 9 followed by addition of a stoichiometric
amount of R2PCl (3, 6) to the resulting mixture affords the
corresponding N-phosphanylenamine compounds 10 and
11, respectively (Scheme 3).
The next step in the preparation of β-enaminoimine li-
gands starting from malonodinitrile was to probe the
monohydrozirconation/transmetalation reaction process.
Treatment of CH2(CN)2 with 1 equiv. of the Schwartz re-
agent [Cp2Zr(H)Cl]n (1), followed by addition of
(iPr2N)2PCl (3) led to the formation of the N-phosphany-
lenamine compound 4 in 66% isolated yield (Scheme 2).
Scheme 2. Selective monohydrozirconation/transmetalation reac-
tions of malonodinitrile and the β-nitriloeneamine compound 4
Scheme 3. Mono-and dihydrozirconation/transmetalation reactions
This compound was identified by its spectroscopic prop- of the phosphanylmalonodinitrile compound 9
erties which included strong absorptions in the IR spectrum
at 1600 and 2194 cmϪ1 assigned to the CϭN and CϵN
stretches, respectively. The 31P NMR spectrum of 4 displays
The IR spectra of 10 and 11 display both CϭN and
a singlet at δ ϭ 87.1 ppm. In addition to signals due to the CϵN stretches. The parent ion peak [M ϩ 1]ϩ detected in
1
isopropyl group, H and 13C NMR spectra display signals the mass spectrum of 11 is in agreement with the general
in the region expected for a CHϭ vinylic group geminal to formula [C3H2N2(PPh2)2]. The 31P NMR spectra of 10 and
an electron-withdrawing group [δ ϭ 3.74 (1H) and 66.1 11 display two singlets at δ ϭ 8.0, 85.2 and δ ϭ Ϫ1.6,
(13C) ppm] and a CHϪNϽ enamine fragment [δ ϭ 6.53 55.1 ppm, respectively. 1H and 13C NMR spectra exhibit
(1H) and 150.8 (13C) ppm]. The broad signal at δ ϭ (besides the chemical shifts corresponding to the protons
1
5.30 ppm in the H NMR is typical of an NH secondary and carbon atoms of the phosphanyl substituents) signals
amine. The NMR spectroscopic data establish 4 as an (N- in the region expected for a CHϪNϽ enamine fragment
phosphanyl-β-enamino)nitrile. Another hydrozirconation/ [10: δ ϭ 7.58 (1H) and δ ϭ 159.1 (13C) ppm; 11: δ ϭ 7.75
transmetalation reaction on the enamine compound 4 using (1H) and δ ϭ 163.7 (13C) ppm]. The broad signal at δ ϭ
1
1 and RЈ2PCl [RЈ ϭ Et (5), Ph (6)] gave the expected un- 5.90 (10) and 8.18 (11) ppm in the H NMR spectra corre-
symmetrical (N-phosphanyl-β-enamino)imine derivatives 7 sponds to the NH secondary amine. The NMR spectro-
and 8, respectively (Scheme 2). IR spectra indicate the dis- scopic data establish an (N-phosphanyl-β-enamino)nitrile
appearance of the ν(CϵN) band in 4 and the appearance skeleton in 10 and 11.
Eur. J. Inorg. Chem. 2003, 960Ϫ968
963

A. Igau, J.-P. Majoral et al.
FULL PAPER
Reaction of 9 with 2 equiv. of 1 and addition of 2 equiv.
of R2PCl (3, 6) allowed isolation of the corresponding N-
phosphanyl-β-diimines 12 and 13, respectively (Scheme 3).
The parent ion [M ϩ 1]ϩ detected in the mass spectrum of
13 was in agreement with the general formula
[C3H3N2(PPh2)3]. Infrared spectra show absorptions at
1633 cmϪ1 (12) and 1635 cmϪ1 (13) assigned to the CϭN
stretch of the enaminoimine fragment. In addition to sig-
1
nals corresponding to the phosphanyl substituents, H and
13C NMR spectra of 12 and 13 show the presence of the β-
diimine NC(H)CC(H)N skeleton. The chemical shifts in
1
both H [δ ϭ 7.90 (12) and 8.35 (13) ppm] and 13C [δ ϭ
161.3 (12) and 166.9 (13) ppm] NMR spectra are consistent
with the CHϭN aldimine and with the central methine PC
fragments the signals of which appear at δ ϭ 99.9 (12) and
103.4 (13) ppm in the 13C NMR spectrum, respectively. The
1
NMR spectroscopic data (13P, H, and 13C) indicate sym-
metric ligand environments, which is consistent with a rapid
tautomeric interconversion. Addition of 1 to the (N-phos-
phanyl-β-enamino)nitrile 10, followed by a substitution re-
action with Me2PCl (15), gave the corresponding unsym-
metrical β-enaminoimine derivative 16 in 84% yield
(Scheme 4).
Figure 3. Two views of the molecular geometry of
Ph2P(S)C[CHNP(S)Ph2]2(µ-H) (14) as determined by X-ray diffrac-
tion
Scheme 4. Monohydrozirconation/transmetalation reactions of the
phosphanyl-β-nitriloeneamine compound 10
˚
Table 1. Selected bond lengths [A] and angles [°] for 14
The 31P NMR spectrum of 16 displays three singlets at
δ ϭ Ϫ4.6 (PPh), 40.6 (PMe), and 86.3 (PNiPr2) ppm. Both
CHϭN aldimine groups exhibit characteristic NMR signals
at δ ϭ 7.91 and 8.29 (1H) ppm and δ ϭ 160.7 and 166.5
(13C) ppm. The 13C NMR chemical shift of the central me-
thine CP fragment (δ ϭ 100.5 ppm) and the upfield shift of
the broad NH signal in the 1H NMR spectrum (δ ϭ
11.39 ppm) establish 16 as having a ‘‘cis-cis’’ configuration,
with a hydrogen-bonded chelate form in a β-enaminoimine
compound.
C(1)ϪC(2)
C(1)ϪP(3)
C(3)ϪN(2)
N(2)ϪP(2)
1.378(7)
1.801(5)
1.298(6)
1.691(5)
1.935(2)
C(1)ϪC(3)
C(2)ϪN(1)
N(1)ϪP(1)
P(1)ϪS(1)
1.424(7)
1.351(6)
1.696(5)
1.926(2)
1.953(2)
P(2)ϪS(2)
P(3)ϪS(3)
C(2)ϪC(1)ϪC(3)
C(1)ϪC(2)ϪN(1)
P(3)ϪC(1)ϪC(2)
C(2)ϪN(1)ϪP(1)
121.0(5)
PϪC(2)ϪN(2)
C(1)ϪC(3)ϪN(2)
P(3)ϪC(1)ϪC(3)
C(2)ϪN(2)ϪP(2)
168.5(2)
124.0(5)
116.1(4)
126.0(4)
124.4(5)
122.9(4)
121.3(4)
presence of the N1ϪH1···N2 intramolecular hydrogen
bond, with an N···N distance of 2.66 A[19] and an NϪH···N
˚
angle of 137°, may be responsible for the planarity of the
X-ray Crystal Structure of 14
system, together with some degree of charge delocalization.
˚
˚
To confirm the spectroscopic assignments and to have a The C2ϪN1 [1.351(6) A] and C3ϪN2 [1.298(6) A] distances
better insight into the molecular structure of the (N-phos- are close to the values reported for CϭCϪNHϪ and
phanyl-β-enamino)imine species prepared, an X-ray C(sp2)ϪCϭNϪ fragments respectively, and are representat-
diffraction study was carried out on the phosphane sulfide ive of single and double bond lengths in such systems.[20,21]
product 14 obtained after addition of elemental sulfur to The thiophosphoryl groups ϪP(S)Ph2 in 14 showed the ex-
13 (Figure 3, Table 1).
pected typical structural parameters.[22]
The crystal structure of 14, recorded at 180 K, shows dis-
The X-ray data recorded at 180 K showed that the β-
crete molecular units which do not display the C2v sym- enaminoimine compound 14 possesses an unsymmetrical
metry previously observed in compound A [R1 ϭ R2 ϭ H, intramolecular hydrogen H(N) bond with two different ni-
R3 ϭ P(S)Ph2].[3,18] All atoms in 14 except those of the trogen chelating atoms, N1 and N2, in the solid state. How-
phenyl groups and the sulfur atoms S1 and S3 lie in the ever, in solution it behaves as a symmetric compound, con-
˚
same plane with a maximum deviation of 0.0046 A. The sistent with the occurrence of a very fast tautomeric proton
964
Eur. J. Inorg. Chem. 2003, 960Ϫ968

Dynamic Behavior of an N-Metalated -Enaminoimine Complex
FULL PAPER
oled to Ϫ50 °C, at which temperature MeI (0.188 µL, 3028 mmol)
in CH2Cl2 (5 mL) was slowly added. The solution was then stirred
for an additional 2 h at room temperature. Removal of the solvent
exchange equilibrium. These observations can be rational-
ized if it is assumed that 14 possesses a low-barrier hydro-
gen bond with a double-well potential. This is in agreement
with the mechanism of proton transfer in malonaldehyde
recently proposed by Silvi and co-workers,[23] involving a
two-step reaction with a concerted charge transfer from one
bond to another within the planar framework of the alde-
hyde. This description may also be applied to the analogous
β-enaminoimine systems.[24]
1
in vacuo gave 2 as an orange solid. H and 13C NMR recorded at
1
293 K: H NMR (CD2Cl2): δ ϭ 4.84 (br, 1 H, CH), 6.35 (s, 10 H,
Cp), 6.53 (s, 10 H, Cp), 7.10 (br., 1 H, NH), 7.48 (dd, JH(2)ϪH(1)
ϭ
5.8, JH(2)-H(N) ϭ 12.6 Hz, CHN) ppm. 13C{1H} NMR (CD2Cl2):
δ ϭ 97.9 (s, CH), 114.5, 116.6 (s, Cp), 157.6 (s, CHN) ppm. 1H
and 13C NMR of conformers I and II recorded at 193 K: 1H NMR
(CD2Cl2): δ ϭ 4.78 (br, 1 H, CH), 6.30 (s, 10 H, Cp), 6.52 (s, 10
H, Cp), 6.70 [d, JH(2)-H(N) ϭ 13.0 Hz, NH), 7.49 (dd, JH(2)ϪH(1)
ϭ
5.5, JH(2)-H(N) ϭ 13.0 Hz, CHN) ppm. 13C{1H} NMR (CD2Cl2):
δ ϭ 97.9 (s, CH), 114.8, 117.0 (s, Cp), 157.6 (s, CHN) ppm. 1H
NMR (CD2Cl2): δ ϭ 4.78 (br, 1 H, CH), 6.30 (s, 10 H, Cp), 6.52
(s, 10 H, Cp), 7.34 (br, CHN and NH) ppm. 13C{1H} NMR
(CD2Cl2): δ ϭ 97.9 (s, CH), 114.8, 117.0 (s, Cp), 158.4 (s, CHN)
ppm.
Conclusion
In conclusion, we have demonstrated that the bis(N-zir-
conated) β-enaminoimine system 2 shows a dynamic NMR
behavior which may be reasonably attributed to a σ-bent/
π-linear fluxional structure. Complex 2 is the ideal synthon
to prepare unsymmetrical β-enaminoimine derivatives fol-
lowing the hydrozirconation/transmetalation reaction se-
quence. Starting with the phosphanylmalononitrile
Ph2PϪCH(CN)2 and using an identical reaction process,
(N-phosphanyl-β-enamino)imine derivatives have been pre-
pared and characterized. These compounds will be further
investigated as ligands in coordination complexes.
The X-ray crystal structure of 14 at 180 K shows an un-
symmetrical system, with the N(H) proton localized on one
of the two chelating nitrogen atoms. This solid-state struc-
tural analysis is consistent with the existence in solution of
a rapidly interconverting pair of tautomers[25] with a low-
barrier proton transfer process corresponding to a double-
well potential. The β-enaminoimine compounds described
in this paper represent a good model for the study of intra-
molecular hydrogen bonding.
Preparation of 4:
A suspension of [Cp2ZrHCl]n (0.600 g,
2.327 mmol) in CH2Cl2 (3 mL) was added to a solution of malono-
dinitrile (2.327 mmol, 0.154 g) in CH2Cl2 (10 mL) at Ϫ40 °C. and
the reaction mixture was allowed to warm slowly to room temper-
ature. As soon as the reaction mixture turned clear, (iPr2N)2PCl
(0.619 mg, 2.327 mmol) in CH2Cl2 (2 mL) was added and the solu-
tion was stirred for 1 h at room temperature. Removal of the solv-
ent in vacuo gave a yellow solid residue which was extracted with
cold pentane (10 mL). After filtration, the volatiles were evaporated
and 4 was obtained as a yellow powder. Yield: 66% (457 mg).
1
31P{1H} NMR (C6D6): δ ϭ 87.1 (s) ppm. H NMR (C6D6): δ ϭ
3
3
1.03 (d, JH,H ϭ 6.7 Hz, 24 H, CH3), 3.24 (d sept, JH,H ϭ 6.7,
3JHP ϭ 11.8 Hz, 4 H, CHCH3), 3.74 (d, JH,H ϭ 8.1 Hz, 1 H,
3
CHCN), 5.30 (br. d, 3JH,H ϭ 15.0 Hz, 1 H, NH), 6.53 (ddd, 3JHP ϭ
3JH,H ϭ 8.1, JH,H ϭ 15.0 Hz, 1 H, CHNH) ppm. 13C NMR
3
3
3
(C6D6): δ ϭ 24.0 (d, JPC ϭ 7.2 Hz, CH3), 24.6 (d, JPC ϭ 7.2 Hz,
CH3), 45.9 (d, JPC ϭ 12.8 Hz, CHCH3), 66.1 (d, JPC ϭ 7.5 Hz,
2
2
2
CHCN), 118.8 (s, CN), 150.8 (d, JPC ϭ 27.7 Hz, CHNH) ppm.
FT-IR (KBr): ν˜ ϭ 1600 (CϭN), 2194 (CϵN) cmϪ1. C15H31N4P
(298.47): calcd. C 60.36, H 10.47, N 18.77; found C 60.48, H 10.28,
N 18.56.
Experimental Section
Typical Procedure for the Synthesis of Compounds 7 and 8: Com-
pound 4 (0.215 g, 0.721 mmol) in CH2Cl2 (2 mL) was added to a
suspension of [Cp2ZrHCl]n (0.186 g, 0.721 mmol) in CH2Cl2
(2 mL) at Ϫ40 °C. The resulting mixture was stirred and allowed
to warm slowly to room temperature. As soon as the solution
turned clear, Et2PCl (0.90 mg, 0.721 mmol) in CH2Cl2 (1 mL) was
added. The mixture was stirred for 15 min at room temperature
and then concentrated to dryness. The volatiles were removed to
give 7 as an orange powder. Yield: 78% (218 mg). 7: 31P{1H} NMR
(C6D6): δ ϭ 64.8 (s, PEt2), 89.3 (s, PNiPr2) ppm. 1H NMR (C6D6):
δ ϭ 0.99 (t, 3JH,H ϭ 7.6 Hz, 3 H, CH2CH3), 1.05 (t, 3JH,H ϭ 7.6 Hz,
General Remarks: All manipulations were performed under argon
in a vacuum line using standard Schlenk techniques. Solvents were
freshly distilled from dark purple solutions of sodium/benzo-
phenone ketyl (THF and toluene), lithium aluminum hydride
(pentane), or CaH2 (CH2Cl2). Deuterated NMR solvents were
treated with LiAlH4 ([D8]toluene, C6D6, [D8]THF) and CaH2
(CD2Cl2), distilled, and stored under argon. Nuclear magnetic res-
onance (NMR) spectra were recorded at 25 °C with Bruker AMX-
400, AM-250, AC-200, and AC-80 Fourier transform spectro-
meters. Chemical shifts are given downfield relative to Me4Si (1H,
13C) or H3PO4 (31P), respectively. 13C NMR assignments were con-
firmed by inverse gradient δ1H-δ13C{13C,31P} HMQC and 31P-1H
NMR experiments. Elemental and mass spectral analyses (obtained
using a Nermag R10-10H) were performed by the analytical service
3
3 H, CH2CH3), 1.16 (d, JH,H ϭ 6.7 Hz, 12 H, CHCH3), 1.19 (d,
3
3
3JH,H ϭ 6.7 Hz, 12 H, CHCH3), 3.50 (d sept, JH,H ϭ 6.7, JHP
11.0 Hz, 4 H, CHCH3), 4.87 (dd, JH,H
ϭ
ϭ
3JH,H ϭ 5.9 Hz, 1 H,
3
CH), 7.55Ϫ7.74 (m, 2 H, CHN), 10.54 (br. m, 1 H, NH) ppm. 13
C
of the Laboratoire de Chimie de Coordination (LCC) of the CNRS.
2
NMR (C6D6): δ ϭ 9.5 (d, JPC ϭ 14.5 Hz, CH2CH3), 24.6 (d,
3JPC ϭ 7.5 Hz, CHCH3), 24.8 (d, 3JPC ϭ 7.5 Hz, CHCH3), 25.0 (d,
2JPC ϭ 12.3 Hz, CH2CH3), 46.3 (d, 2JPC ϭ 12.5 Hz, CHCH3), 97.6
[27]
(iPr2N)2PCl[26] and [Cp2Zr(H)Cl]n
were prepared according to
literature procedures. Ph2PCl (Aldrich), Me2PCl (Strem), Et2PCl
(Strem), MeI (Aldrich), and CH2(CN)2 (Aldrich) were purchased
and used without further purification.
3
2
(dd, JPC
ϭ
3JPC ϭ 13.6 Hz, CH), 156.1 (d, JPC ϭ 37.3 Hz,
2
CHNPNiPr), 159.8 (d, JPC ϭ 27.4 Hz, CHNPEt) ppm. FT-IR
Preparation of 2: A solution of CH2(CN)2 (0.100 g, 1.514 mmol) in (KBr): ν˜ ϭ 1625 (CϭN) cmϪ1. C19H42N4P2 (388.59): calcd. C
CH2Cl2 (5 mL) was added to a suspension of [Cp2Zr(H)Cl]n 58.72, H 10.89, N 14.42; found C 58.89, H 11.61, N 14.29. 8 [1
(0.781 g, 3.028 mmol) in CH2Cl2 (3 mL) at Ϫ30 °C. The reaction (0.233 g), 4 (0.270 g), 6 (0.199 g)] isolated as an orange-yellow pow-
mixture was stirred for 30 min at room temperature and then co-
der. Yield: 87% (0.380 g). 31P{1H} NMR (C6D6): δ ϭ 53.3 (s,
Eur. J. Inorg. Chem. 2003, 960Ϫ968
965

A. Igau, J.-P. Majoral et al.
FULL PAPER
PPh2), 84.5 (s, PNiPr2) ppm. 1H NMR (C6D6): δ ϭ 1.05 (d, 3JH,H ϭ
3
δ
ϭ
7.28Ϫ7.65 (m, 20 H, Ph), 7.75 (ddd, JH,H
ϭ
14.5,
3
3
6.7 Hz, 12 H, CHCH3), 1.09 (d, JH,H ϭ 6.7 Hz, 12 H, CHCH3),
3JHP(NPPh2) ϭ 10.3, JHP(C,PPh2) ϭ 9.5 Hz, 1 H, CHNH), 8.18 (dd,
3
3
2
3·32 (dsept, JH,H ϭ 6.7, JHP ϭ 11.0 Hz, 4 H, CHCH3), 4.89
3JH,H ϭ 4.0, JHp ϭ 14.5 Hz, 1 H, NH) ppm. 13C NMR (C6D6):
(dddd, JH,H ϭ JH,H ϭ 6.7, JHP(Ph) ϭ 4.9, JHP(NiPr) ϭ 1.5 Hz, 1 δ ϭ 80.0 (dd, 1JC,P ϭ 17.6, 3JC,P ϭ 10.4 Hz, PC), 118.4 (d, 2JC,P
ϭ
3
3
4
4
3
3
H, CH), 7.41Ϫ7.60 (m, 10 H, Ph), 7.82Ϫ7.96 (m, 2 H, CHN), 10.84 5.0 Hz, CN), 130.3 (d, JC,P ϭ 6.9 Hz, m-Ph), 130.6 (d, JC,P
ϭ
(br. d, JHP ϭ 9.9 Hz, 1 H, NH) ppm. 13C NMR (C6D6): δ ϭ 24.5 6.9 Hz, m-Ph), 131.6 (s, p-Ph), 133.6 (d, JC,P ϭ 19.9 Hz, o-Ph),
2
2
3
3
2
1
(d, JPC ϭ 7.3 Hz, CH3), 24.7 (d, JPC ϭ 7.3 Hz, CH3), 46.4 (d,
134.6 (d, JC,P ϭ 19.9 Hz, o-Ph), 139.9 (d, JC,P ϭ 16.1 Hz, i-Ph),
3
3
1
2
2JC,P ϭ 12.3 Hz, CHCH3), 97.8 (dd, JC,P(Ph) ϭ 10.7, JC,P(NiPr)
ϭ
140.1 (d, JC,P ϭ 16.2 Hz, i-Ph), 163.7 (dd, JC,P(C,PPh2) ϭ 70.0,
13.4 Hz, CH), 128.9 (d, JC,P ϭ 7.0 Hz, m-Ph), 129.5 (s, p-Ph), 2JC,P(NPPh) ϭ 37.5 Hz, CHNP) ppm. FT-IR (KBr): ν˜ ϭ 1642 (Cϭ
3
2
1
132.0 (d, JC,P ϭ 20.7 Hz, o-Ph), 141.6 (d, JC,P ϭ 16.6 Hz, i-Ph),
N), 2202 (CϵN) cmϪ1. MS (DCI/CH4): m/z ϭ 437 [M ϩ H]ϩ.
2
2
150.5 (d, JC,P ϭ 33.2 Hz, CHNPPh), 164.5 (d, JPC ϭ 15.1 Hz, C27H22N2P2 (436.45): calcd. C 74.30, H 5.08, N 6.42; found C
CHNPNiPr2) ppm. FT-IR (KBr): ν˜
ϭ
1621 (CϭN) cmϪ1
.
74.45, H 4.94, N 6.32.
C27H42N4P2 (484.67): calcd. C 66.91, H 8.73, N 11.56; found C
67.15, H 8.66, N 11.39.
Typical Procedure for the Synthesis of Compounds 12 and 13: A
solution of 9 (0.270 g, 1.078 mmol) in THF (2 mL) was added to a
Preparation of 9: CH2(CN)2 (0.480 g, 0.076 mmol) in THF (5 mL) suspension of [Cp2ZrHCl]n (0.556 g, 2.156 mmol) in THF (3 mL)
was added slowly to a solution of LDA (0.779 g, 0.0726 mmol) in at Ϫ40 °C. The resulting mixture was stirred and slowly warmed
THF (25 mL) at 0 °C. The mixture was stirred at 0 °C for 1 h, then to room temperature. As soon as the reaction mixture turned clear
Ph2PCl (1.600 g, 0.076 mmol) in THF (5 mL) was added dropwise.
The mixture was slowly warmed to room temperature over 1 h,
filtered, and the solvent was evaporated. The resulting solid residue
was washed with Et2O (2 ϫ 20 mL). The volatiles were removed in
a vacuum line over 5 h at 80 °C to give 9 as a yellow-brown
solid.Yield: 95% (1.514 g). M.p. 83Ϫ84 °C. 31P{1H} NMR
(ca. 30 min), (iPr2N)2PCl (0.574 mg, 2.156 mmol) in THF (2 mL)
was added. After stirring for 4 h, the solution was concentrated
to dryness. The resulting solid residue was extracted with CH2Cl2/
pentane (1:4, 30 mL) and filtered. The volatiles were evaporated to
give 16 as a yellow solid. Yield 67% (516 mg).
Data for 12: 31P{1H} NMR (C6D6): δ ϭ Ϫ1.8 (PPh2), 86.2 (PNiPr2)
([D8]THF): δ ϭ Ϫ5.9 ppm. 1H NMR ([D8]THF): δ ϭ 7.18Ϫ7.50
1
3
ppm. H NMR (C6D6): δ ϭ 1.02 (d, JH,H ϭ 6.6 Hz, 24 H, CH3),
1
(m, 10 H, Ph) ppm. 13C NMR ([D8]THF): δ ϭ 7.9 (d, JC,P
ϭ
3
3
1.21 (d, JH,H ϭ 6.6 Hz, 24 H, CH3), 3.54 (dsept, JH,H ϭ 6.6,
5.8 Hz, PC), 127.4 (s, p-Ph), 127.9 (d, 3JC,P ϭ 6.2 Hz, m-Ph), 128.4
3JHP ϭ 12.3 Hz, 8 H, CHCH3), 6.90Ϫ7.58 (m, 10 H, Ph), 7.90
(d, 2JC,P ϭ 21.1 Hz, CN), 132.5 (d, 2JC,P ϭ 19.4 Hz, o-Ph), 142.2 (d,
3
3
3
(ddd, JH,H ϭ 7.3, JHP(PPh) ϭ 7.3, JHP(PniPr) ϭ 18.0 Hz, 2 H,
CHNH), 10.35 (br. m, 1 H, NH) ppm. 13C NMR (C6D6): δ ϭ 24.4
1JC,P ϭ 11.2 Hz, i-Ph) ppm. FT-IR (KBr): ν˜ ϭ 2189 (CϵN) cmϪ1
.
3
3
Preparation of 10: A solution of 9 (0.262 g, 1.046 mmol) in THF
(2 mL) was added to a suspension of [Cp2ZrHCl]n (0.270 g,
1.046 mmol) in THF (2 mL) at Ϫ40 °C. The resulting mixture was 128.1 (s, p-Ph), 128.7 (d, JC,P ϭ 5.5 Hz, m-Ph), 133.0 (d, JC,P
(d, JC,P ϭ 7.0 Hz, CH3), 24.8 (d, JC,P ϭ 7.0 Hz, CH3), 47.9 (d,
2JPC ϭ 13.1 Hz, CHCH3), 99.9 (dd, JPC
ϭ
3JPC ϭ 9.3 Hz, PC),
1
3
2
ϭ
1
stirred and allowed to warm slowly to room temperature. As soon
as the reaction mixture turned clear, (iPr2N)2PCl (0.278 mg,
1.046 mmol) in THF (2 mL) was added. The solution was stirred
for 30 min at room temperature and the solvent was then removed.
The resulting solid residue was extracted with pentane (20 mL) and
filtered. The volatiles were removed and 10 was obtained as a yel-
low-orange solid. Yield: 55% (277 mg). 31P{1H} NMR (C6D6): δ ϭ
Ϫ8.0 (PPh2), 85.2 (PNiPr2) ppm. 1H NMR (C6D6): δ ϭ 1.01 (d,
17.6 Hz, o-Ph), 141.0 (d, JC,P ϭ 11.4 Hz, i-Ph), 161.3 (dd,
2JC,P(PPh2) ϭ 36.1, JHP(PNiPr) ϭ 20.6 Hz, CHNP) ppm. FT-IR
2
(KBr): ν˜ ϭ 1633 (CϭN) cmϪ1. C39H69N6P3 (715.05): calcd. C
65.51, H 9.72, N 11.75; found C 65.72, H 9.65, N 11.68.
Data for 13: Yield: 54% (229 mg). M.p. 126Ϫ127 °C (dec). 31P{1H}
NMR (C6D6): δ ϭ Ϫ3.6 (CPPh2), 54.9 (NPPh2) ppm. 1H NMR
3
(C6D6): δ ϭ 7.00Ϫ8.15 (m, 30 H, Ph), 8.35 (ddd, JH,H
ϭ
3JHP(C,PPh) ϭ 6.1, JHP(NPPh) ϭ 16.9 Hz, 2 H, CHNH), 12.55 (tt,
3
3
3JH,H ϭ 6.7 Hz, 12 H, CH3), 1.05 (d, JH,H ϭ 6.7 Hz, 12 H, CH3),
3JH,H ϭ JHP(NPPh) ϭ 6.1 Hz, 1 H, NH) ppm. 13C NMR (C6D6):
3
3
3
3.23 (d sept, JH,H ϭ 6.7, JHP ϭ 11.6 Hz, 4 H, CHCH3), 5.95 (br.
1
3
δ ϭ 103.4 (dt, JC,P(CPPh) ϭ 6.3, JC,P(NPPh) ϭ 10.3 Hz, PC), 128.4
(s, p-NPPh), 128.9 (d, JC,P ϭ 5.1 Hz, m-CPPh), 129.0 (d, JC,P
6.7 Hz, m-NPPh), 129.5 (s, p-CPPh), 132.2 (d, JC,P ϭ 20.6 Hz, o-
3
3
dd, JH,H ϭ 2.0, JHP ϭ 15.6 Hz, 1 H, NH), 7.00Ϫ7.28 (m, 5 H,
Ph), 7.58 (ddd, 3JH,H ϭ 7.1, 3JHP(PPh2) ϭ 15.6, 3JHP(PNiPr) ϭ 9.5 Hz,
1 H, CHNH), 7.65Ϫ7.77 (m, 5 H, Ph) ppm. 13C NMR (C6D6): δ ϭ
3
3
ϭ
2
3
3
24.4 (d, JPC ϭ 8.2 Hz, CH3), 24.7 (d, JPC ϭ 8.2 Hz, CH3), 46.2
(d, 2JPC ϭ 12.3 Hz, CHCH3), 76.3 (dd, 1JPC ϭ 16.0, 3JPC ϭ 5.8 Hz,
Table 2. Crystallographic data for 14
1
PC), 129.2 (s, p-Ph), 129.3 (s, m-Ph), 133.5 (d, JC,P ϭ 20.0 Hz, o-
Ph), 139.0 (d, 1JC,P ϭ 5.8 Hz, i-Ph), 159.1 (dd, 2JC,P ϭ 21.1, 2JC,P ϭ
67.3 Hz, PCCH) ppm. FT-IR (KBr): ν˜ ϭ 1619 (CϭN), 2195
Empirical formula
Formula mass
C39H33N2P3S3
718.76
(CϵN) cmϪ1. C27H40N4P2 (482.65): calcd. C 67.19, H 8.35, N Temperature
180(2) K
˚
Wavelength
0.71073 A
11.61; found C 67.35, H 8.12, N 11.45.
Crystal system, space group
Unit cell dimensions
monoclinic, P21/c
˚
Preparation of 11: A solution of 9 (340 mg, 1.356 mmol) in THF
(2 mL) was added to a suspension of [Cp2ZrHCl]n (250 mg,
1.356 mmol) in THF (2 mL) at Ϫ40 °C. The resulting mixture was
stirred and allowed to warm slowly to room temperature. As soon
as the solution turned clear (ca. 20 min), Ph2PCl (300 mg,
1.356 mmol) in THF (2 mL) was added. The resulting mixture was
stirred at room temperature for 30 min and then concentrated to
dryness. The solid residue was extracted with CH2Cl2/pentane (1:5,
20 mL) and filtered. The volatiles were removed to give 11 as a
white solid. Yield: 66% (391 mg). M.p. 155Ϫ156 °C. 31P{1H} NMR
a ϭ 14.804(5) A
˚
b ϭ 12.238(5) A
˚
c ϭ 20.169(5) A
β ϭ 93.710(5)°
3
˚
Volume
3646(2) A
Z, calculated density
Absorption coefficient
F(000)
4, 1.309 mg/m3
0.366 mmϪ1
1496
Final R indices [I Ͼ 2σ(I)]
R indices (all data)
Largest diff. peak and hole
R1 ϭ 0.0524, wR2 ϭ 0.0638
R1 ϭ 0.1710, wR2 ϭ 0.0901
0.279 and Ϫ0.315 e A
Ϫ3
˚
1
(C6D6): δ ϭ Ϫ1.6 (CPPh2), 55.1 (NPPh2) ppm. H NMR (C6D6):
966
Eur. J. Inorg. Chem. 2003, 960Ϫ968

Dynamic Behavior of an N-Metalated -Enaminoimine Complex
FULL PAPER
atom connected to N(1), was refined isotropically. All non-hydro-
2
1
NPPh), 133.0 (d, JC,P ϭ 18.6 Hz, o-CPPh), 139.8 (d, JC,P
ϭ
1
10.1 Hz, i-CPPh), 140.3 (d, JC,P ϭ 13.1 Hz, i-NPPh), 166.9 (dd, gen atoms were refined anisotropically, and the weighting scheme
2JC,P(C,PPh) ϭ 34.5, JHP(NPPh) ϭ 25.5 Hz, CHNP) ppm. FT-IR w ϭ 1/[σ2(F2o) ϩ (aP)2 ϩ bP], where P ϭ (F2o ϩ 2F2c)/3, was used
2
(KBr): ν˜ ϭ 1635 (CϭN) cmϪ1. MS (DCI/CH4): m/z ϭ 623 [M ϩ in the last cycles of refinement. Molecular graphics were produced
H]ϩ. C39H33N2P3 (622.63): calcd. C 75.23, H 5.34, N 4.50; found
C 75.41, H 5.23, N 4.33.
using ZORTEP,[31] with non-hydrogen atoms drawn at the 50%
probability level. CCDC-196233 contains the supplementary crys-
tallographic data for this paper. These data can be obtained free
of charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or from the
Cambridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; Fax: (internat.) ϩ 44-1223/336-033; E-mail:
deposit@ccdc.cam.ac.uk].
Preparation of 14: Treatment of 13 (362 mg, 0.581 mmol) in CH2Cl2
(8 mL) with an excess of sulfur at room temperature for 12 h af-
forded 14, which was purified by column chromatography (silica
gel, pentane/ethyl acetate, 1:4, Rf ϭ 0.49). The product crystallized
from toluene as colorless crystals. Yield: 81% (338 mg). M.p.
185Ϫ186 °C. 31P{1H} NMR (400 MHz, 233 K, [D8]toluene): δ ϭ
43.5 [CP(S)Ph2], 63.2 [NP(S)Ph2] ppm. 1H NMR (400 MHz, 233 K,
[D8]toluene): δ ϭ 7.46Ϫ8.04 (m, 30 H, Ph), 9.59 (ddd, 3JH,H ϭ 5.8,
Acknowledgments
Financial support of this work by the CNRS, France, is gratefully
acknowledged. This work was completed with the support of the
European Associate Laboratory financed by the CNRS (France)
and the Polish Committee for Scientific Research (KBN grant no.
3TO9A03619, Poland).
3
3JHP(NPPh) ϭ 8.5, JHP(C,PPh) ϭ 23.5 Hz, 2 H, CHNH), 13.59 (tt,
2
3JH,H ϭ 5.8, JHP(NPPh) ϭ 5.0 Hz, 1 H, NH) ppm. 13C NMR
1
3
(C6D6): δ ϭ 102.8 (dt, JC,P(C,PPh) ϭ 97.1, JC,P(NPPh) ϭ 14.0 Hz,
3
PC), 128.7 (d, JC,P ϭ 13.8 Hz, m-Ph), 129.3 (s, p-Ph), 131.0 (d,
2JC,P ϭ 11.5 Hz, o-Ph), 134.4 (d, JC,P ϭ 96.0 Hz, i-Ph), 164.4 (d,
1
2JC,P ϭ 19.7 Hz, CHNP) ppm. FT-IR (KBr): ν˜(CϭN) 1596 cmϪ1
.
MS (DCI/CH4): m/z ϭ 719 [M ϩ H]ϩ. C39H33N2P3S3 (718.65):
[1] [1a]
N. Tyutyulkov, J. Fabian, A. Melhorn, F. Dietz, A. Tadjer,
calcd. C 65.18, H 4.63, N 3.90; found C 65.05, H 4.45, N 3.79.
Polymethine Dyes, Structure and Properties, St Kliment Ohrid-
ski University Press, Sofia, 1991. [1b] A. D. Kachkovski, ‘‘Poly-
methine Dyes’’, in: Kirk-Othmer Encyclopedia of Chemical
Technology; 4th ed., John Wiley & Sons, New York, 1996, vol.
19, pp. 1004Ϫ1030.
Preparation of 16: A solution of 10 (0.351 g, 0.729 mmol) in
CH2Cl2 (2 mL) was added to a suspension of [Cp2ZrHCl]n (0.556 g,
2.156 mmol) in CH2Cl2 (2 mL) at Ϫ40 °C. The resulting mixture
was stirred and slowly warmed to room temperature. As soon as
the reaction mixture turned clear (ca. 20 min), Me2PCl (0.070 g,
0.729 mmol) in CH2Cl2 (2 mL) was added. After stirring for
15 min, the solution was concentrated to dryness. The resulting
solid residue was extracted with pentane (30 mL) and filtered. The
volatiles were removed to give 16 as a yellow solid. Yield: 84%
(0.334 g). 31P{1H} NMR (C6D6): δ ϭ Ϫ4.6 (PPh2), 40.6 (PMe2),
86.3 (PNiPr2) ppm. 1H NMR (C6D6): δ ϭ 1.06 (d, 2JH,H ϭ 4.5 Hz,
6 H, PCH3), 1.09 (d, 3JH,H ϭ 6.5 Hz, 12 H, CH3), 1.14 (d, 3JH,H ϭ
[2]
[2a]
For some recent examples see:
N. Burford, P. J. Ragogna,
K. N. Robertson, T. S. Cameron, J. Am. Chem. Soc. 2002, 124,
[2b]
382Ϫ383.
S. B. Cortright, J. N. Johnston Parsons, Angew.
Chem. 2002, 114, 355Ϫ358; Angew. Chem. Int. Ed. 2002, 41,
345Ϫ348. [2c] A. M. Neculai, H. W. Roesky, D. Neculai, J. Mag-
ull, Organometallics 2001, 20, 5501Ϫ5503. [2d] P. J. Bailey, S. T.
Liddle, C. A. Morrison, S. Parsons, Angew. Chem. 2001, 113,
4595Ϫ4598; Angew. Chem. Int. Ed. 2001, 40, 4463Ϫ4466. [2e] J.
M. Smith, R. J. Lachicotte, K. A. Pittard, T. R. Cundari, G.
Lukat-Rodgers, K. R. Rodgers, P. L. Holland, J. Am. Chem.
3
3
6.5 Hz, 12 H, CH3), 3.41 (dsept, JH,H ϭ 6.5, JHP ϭ 11.3 Hz, 4
H, CHCH3), 6.86Ϫ7.72 (m, 10 H, Ph), 7.91 (m, 1 H, CHNPNiPr),
8.29 (m, 1 H, CHNPMe), 11.39 (br. m, 1 H, NH) ppm. 13C NMR
(C6D6): δ ϭ 18.9 (d, 1JC,P ϭ 17.0 Hz, CH3), 24.6 (d, 3JC,P ϭ 8.4 Hz,
[2f]
Soc. 2001, 123, 9222Ϫ9223.
V. C. Gibson, J. A. Segal, A. J.
P. White, D. J. Williams, J. Am. Chem. Soc. 2000, 122,
7120Ϫ7121. [2g] C. Cui, H. W. Roesky, H. Hao, H.-G. Schmidt,
M. Noltemeyer, Angew. Chem. 2000, 112, 1885Ϫ1887; Angew.
3
2
[2h]
CH3), 24.7 (d, JC,P ϭ 8.4 Hz, CH3), 46.4 (d, JC,P ϭ 12.8 Hz,
Chem. Int. Ed. 2000, 39, 1815Ϫ1817.
S. K. Bertilsson, L.
3
CHCH3), 100.5 (d, JC,P ϭ 9.2 Hz, PC), 129.1 (s, p-Ph), 129.2 (d,
Tedenborg, D. A. Alonso, P. G. Andersson, Organometallics
1999, 18, 1281Ϫ1286.
3JC,P ϭ 8.0 Hz, m-Ph), 133.2 (d, JC,P ϭ 17.6 Hz, o-Ph), 140.7 (d,
2
[3]
[4]
1JC,P ϭ 10.9 Hz, i-Ph), 160.7 (dd, JC,P(PPh2) ϭ 34.6, JC,P(PNiPr)
ϭ
2
2
A. Maraval, D. Arquier, A. Igau, Y. Coppel, B. Donnadieu, J.
P. Majoral, Organometallics 2001, 20, 1716Ϫ1718.
The selective GaussianϪshaped pulse was applied at the central
methine proton: T. Fäcke, S. Berger, J. Magn. Reson. A 1995,
113, 257Ϫ259. A 1D TOCSY experiment was employed in or-
der to identify the H(N) proton whose signal overlaps with that
of the Cp groups.
Note that the NH(N) proton resonance occurred at a consider-
ably higher field than in previously reported β-enaminoimine
systems,[3,6] possibly due to the presence of the zirconated metal
fragment bonded to the nitrogen atoms.[7]
2
2
28.8 Hz, CHNPNiPr), 166.5 (dd, JC,P(PPh) ϭ 35.0, JC,P(PMe)
ϭ
18.9 Hz, CHNPMe) ppm. FT-IR (KBr): ν˜ ϭ 1593 (CϭN) cmϪ1
.
C29H47N4P3 (544.71): calcd. C 63.94, H 8.70, N 10.28; found C
63.92, H 8.56, N 10.35.
X-ray Analysis of 14: Single crystals of 14 were obtained from tolu-
ene. Data (Table 2) were collected at 180 K with an IPDS STOE
diffractometer equipped with an Oxford Cryosystems Cryostream
Cooler Device using graphite-monochromated Mo-Kα radiation
[5]
[6]
˚
(λ ϭ 0.71073 A). The final unit cell parameters were obtained by
See this work and: P. H. M. Budzelaar, N. N. P. Moonen, R.
de Gelder, J. M. M. Smits, A. W. Gal, Eur. J. Inorg. Chem.
2000, 753Ϫ769.
means of a least-squares refinement performed on a set of 5000
strong reflections. No significant intensity fluctuations were ob-
served during the data collection, indicating crystal decay was min-
imal. The structure was solved by Direct Methods using SIR92,[28]
and refined by means of least-squares procedures on F2 using
SHELXL-97.[29] Atomic scattering factors were taken from the In-
ternational Tables for X-ray Crystallography.[30] All hydrogen
atoms were located in a difference Fourier map, and, with the ex-
ception of H(N), were refined using a riding model with an iso-
tropic thermal parameter fixed at 20% greater than those of the
carbon atoms to which they are connected. H(N), the hydrogen
[7] [7a]
P. J. Walsh, A. M. Baranger, R. G. Bergman, J. Am. Chem.
Soc. 1992, 114, 1708Ϫ1719. [7b] P. J. Walsh, J. Hollander, R. G.
Bergman, J. Am. Chem. Soc. 1988, 110, 8729Ϫ8731.
[8]
The 1D GROESY experiment is
a
combination of the
K. Stott, J. Stonehouse, J. Keeler,
T.-L. Hwang, A.-J. Shaka, J. Am. Chem. Soc. 1995, 117,
[8a]
DPFGSE sequence; see:
[8b]
4199Ϫ4200 and the TROESY spin-lock, see:
T. L. Hwang,
A. J. Shaka, J. Magn. Reson. B 1993, 102, 155Ϫ165.
[9] [9a]
[9b]
R. Knorr, A. Weiß, Chem. Ber. 1982, 115, 139Ϫ160.
H.
H. Limbach, W. Seiffert, Tetrahedron Lett. 1972, 371Ϫ374.
Eur. J. Inorg. Chem. 2003, 960Ϫ968
967

A. Igau, J.-P. Majoral et al.
FULL PAPER
[9c]
K. Feldmann, E. Daltrozzo, G. Scheibe, Z. Naturforsch.,
in the N···N region of the molecule, similar to what might be
obtained by the superposition of one half molecule of AЈ on
one half molecule of AЈЈ.
Teil B 1967, 22, 722Ϫ731.
For the ‘‘cis-cis’’ configuration, JH(2)-H(1) Ͻ 7 Hz. For the
[10]
3
[19]
3
[10a]
The observed nitrogenϪnitrogen separation [N1ϪN2
ϭ
‘‘trans-trans’’ configuration, JH(2)-H(1) Ͼ 10 Hz; see:
Jutz, A. F. Kirschner, R.-M. Wagner, Chem. Ber. 1977, 110,
C.
˚
2.657(6) A] is smaller than the sum of the nitrogen van der
Waals radii (3.10 A); see: A. Bondi, J. Chem. Phys. 1964, 68,
˚
[10b]
1259.
R. Knorr, A. Weiß, H. Polzer, Tetrahedron Lett.
[10c]
441. R. C. Weast, Handbook of Chemistry and Physics, CRC,
Boca Raton, FL, 1974.
1977, 459.
mun. 1968, 739Ϫ740.
C. L. Honeybourne, G. A. Webb, Chem. Com-
[20] [20a]
[11] 13C NMR [CH(1)]: For the cis-cis configuration, 130 ppm Ͻ δ
Ͻ 150 ppm. For the trans-trans configuration 90 ppm Ͻ δ Ͻ
110 ppm; see ref.[11]
M. Stender, R. J. Wright, B. E. Eichler, J. Prust, M. M.
Olmstead, H. W. Roesky, P. P. Power, J. Chem. Soc., Dalton
Trans. 2001, 3465Ϫ3469. [20b] R. M. Claramunt, D. Sanz, S. H.
Alarcon, M. P. Torralba, J. Elguero, C. Foces-Foces, M. Pi-
[12]
Simple close-contact calculations were carried out on complex
etrzak, U. Langer, H. Limbach, Angew. Chem. 2001, 113,
2 (I) using standard Cp2Zr(Cl) fragment parameters and the β-
enaminoimine skeleton ϪN(H)Ϫ(CH)2ϪCHϭNϪ from the X-
ray crystal structure of 14. The Cambridge Structural Database
was used to determine the mean ZrϪN bond lengths in amido
[20c]
434Ϫ437; Angew. Chem. Int. Ed. 2001, 40, 420Ϫ423.
F. H.
Allen, O. Kennard, D. G. Watson, L. Brammer, A. G. Orpen,
[20d]
R. Taylor, J. Chem. Soc., Perkin. Trans. 2 1987, S1.
S.
˚
˚
Brownstein, E. J. Gabe, L. Prasad, Can. J. Chem. 1983, 61,
1410Ϫ1413.
A. G. Orpen, L. Brammer, F. H. Allen, O. Kennard, D. G.
Watson, R. Taylor, in: Structure Correlation (Eds.: H.-B. Bürgi,
J. D. Dunitz), VCH, Weinheim, 1994, vol. 2, pp. 770Ϫ774.
See for example: [22a] V. Cadierno, M. Zablocka, B. Donnadieu,
(2.15 A) and ketimide (2.04 A) zirconocene complexes (note
that from the CSD, group-4 metallocene amido complexes ex-
hibit a planar nitrogen atom with a Cp2MϪNϪC angle from
135 to 150° and zirconocene ketimide complexes contain
CϪNϪZr angle values from 164 to 178°). On varying the
CϪNϪZr angle value from 120 to 180° in 2 (I), rotation
around the ZrϪN bond revealed that: i) van der Waals contacts
between Cp ring hydrogen atoms and the hydrogen atom of the
HϪCϭN fragment are observed up to a CϪNϪZr angle value
of 150°, ii) van der Waals contacts between the Cp ring hydro-
gen atoms of the two Cp2ClZr metal moieties are not observed
for a CϪNϪZr angle lower than 130° in the amido and ketim-
ide subunits. For a good discussion of orbital constraints and
symmetry requirements of the bent metallocene derivatives,
see: J. W. Lauher, R. Hoffmann, J. Am. Chem. Soc. 1976, 98,
1729.
[21]
[22]
A. Igau, J. P. Majoral, A. Skowronska, J. Am. Chem. Soc. 1999,
[22b]
121, 11086Ϫ11092.
Y. Miquel, A. Igau, B. Donnadieu, J.
P. Majoral, L. Dupuis, N. Pirio, P. Meunier, Chem. Commun.
1997, 279Ϫ280.
X. Krokidis, V. Goncalves, A. Savin, B. Silvi, J. Phys. Chem.
A. 1998, 26, 5065Ϫ5073.
The representation of β-enaminoimine systems as a symmetric-
ally hydrogen-bonded structure, earlier described as an aro-
matic six-π-electron system, should be excluded for these com-
[23]
[24]
[24a]
pounds; see:
P. Goldstein, K. N. Trueblood, Acta Crys-
tallogr. 1967, 23, 148Ϫ156. [24b] J. E. Parks, R. H. Holm, Inorg.
Chem. 1968, 7, 1408Ϫ1416.
[13]
See for example: G. L. Hillhouse, A. R. Bulls, B. D. Santarsi-
ero, J. E. Bercaw, Organometallics 1988, 7, 1309Ϫ1312.
[25]
[26]
A very low activation barrier has to be assumed for the tauto-
meric process in β-enaminoimine derivatives.
R. B. King, P. M. Sundaram, J. Org. Chem. 1984, 49,
1784Ϫ1789.
[14] [14a]
G. Erker, W. Frömberg, J. L. Atwood, W. E. Hunter, An-
gew. Chem. 1984, 96, 72Ϫ73; Angew. Chem. Int. Ed. Engl. 1984,
[14b]
23, 68Ϫ69.
W. Frömberg, G. Erker, J. Organomet. Chem.
1985, 280, 343Ϫ354. [14c] G. Erker, W. Frömberg, C. Krüger, E.
Raabe, J. Am. Chem. Soc. 1988, 110, 2400Ϫ2405. See also for
the X-ray structures of (alkylideneamido)zirconocene com-
[27] [27a] S. L. Buchwald, S. J. LaMaire, R. B. Nielsen, B. T. Watson,
[27b]
S. M. King, Org. Synth 1993, 71, 77.
S. L. Buchwald, S. J.
LaMaire, R. B. Nielsen, B. T. Watson, S. M. King, Tetrahedron
Lett. 1987, 28, 3895Ϫ3898.
SIR92, a Program for Automatic Solution of Crystal Structures
by Direct Methods: A. Altomare, G. Cascarano, G. Giacov-
azzo, A. Guargliardi, M. C. Burla, G. Polidori, M. Camalli, J.
Appl. Crystallogr. 1994, 27, 435Ϫ440.
G. M. Sheldrick, SHELXTL-97 (includes SHELXS-97,
SHELXL-97, CIFTAB), Programs for Crystal Structure Ana-
lysis (Release 97-2), Institut für Anorganische Chemie der Un-
iversität, Tammanstrasse 4, 3400 Göttingen, Germany, 1998;
SHELXS-97 and SHELXL-97 are both included in the pack-
age WinGX version 1.63 (WINGX-1.63, Integrated System of
Windows Programs for the Solution, Refinement and Analysis of
Single Crystal X-ray Diffraction Data): L. Farrugia, J. Appl.
Crystallogr. 1999, 32, 837Ϫ838].
[14d]
plexes:
D. R. Armstrong, K. W. Henderson, I. Little, C.
Jenny, A. R. Kennedy, A. E. McKeown, R. E. Mulvey, Organo-
[28]
[29]
[14e]
metallics 2000, 19, 4369Ϫ4375.
U. Segerer, S. Blaurock, J.
Sieler, E. Hey-Hawkins, Organometallics 1999, 18, 2838Ϫ2842.
[15] [15a]
G. Erker, W. Frömberg, R. Benn, R. Mynott, K. An-
[15b]
germund, C. Krüger, Organometallics 1989, 8, 911Ϫ920.
G. Erker, Angew. Chem. 1989, 101, 411Ϫ417; Angew. Chem.
Int. Ed. Engl. 1989, 28, 397Ϫ412.
Alternative structures for 2 which involve the formation of
dimers, trimers, or oligomers with the zirconated metal frag-
ment cannot be totally ruled out, but it is highly unlikely as it
will prevent any fluxional process within the alkylideneamido
subunit.
[16]
[17]
Rate constants were derived from band-shape analysis using
the software MEXICO (available from A. D. Bain, Department
of Chemistry, McMaster University, Hamilton, Ontario, Can-
ada). NMR parameters were optimized to match the simulated
and the experimental data. Activation parameters were deter-
mined by a standard Eyring analysis.
[30]
[31]
International Tables for X-ray Crystallography, Kynoch Press,
Birmingham, England, 1974, vol. IV.
L. Zolna¨ı, ZORTEP, Graphical Program for X-ray Structure
Analysis, University of Heidelberg, Heidelberg, Germany,
1998.
The X-ray crystallographic investigation of A [R1 ϭ R2 ϭ H,
R3 ϭ P(S)Ph2] at 293 K revealed two ‘‘half-hydrogen’’ atoms
Received March 19, 2002
[18]
[I02144]
968
Eur. J. Inorg. Chem. 2003, 960Ϫ968