2-Chloro-1,3,2-diazaphospholenes - A crystal structural study

Article abstract of DOI:10.1002/ejic.200700643

A series of 2-chloro-1,3,2-diazaphospholenes with different substitution patterns has been prepared from 1,4-diazabutadienes according to a general synthetic methodology. Subsequent chloride abstraction with Lewis acids affords the corresponding 1,3,2-dia

Full text of DOI:10.1002/ejic.200700643

FULL PAPER
DOI: 10.1002/ejic.200700643
2-Chloro-1,3,2-diazaphospholenes – A Crystal Structural Study
Sebastian Burck,[a] Dietrich Gudat,*[a] Kalle Nättinen,[b] Martin Nieger,[c] Mark Niemeyer,[a]
and Dirk Schmid[a]
Keywords: Phosphanes / Halides / X-ray diffraction / Substituent effects / Structure correlation
A series of 2-chloro-1,3,2-diazaphospholenes with different
substitution patterns has been prepared from 1,4-diazabuta-
dienes according to a general synthetic methodology. Subse-
quent chloride abstraction with Lewis acids affords the corre-
sponding 1,3,2-diazaphospholenium salts. All products have
been characterised spectroscopically and by single-crystal X-
ray diffraction studies. A detailed analysis of trends in the
structural parameters supports the interpretation that the un-
usual P–Cl bond lengthening in the diazaphospholenes is at-
tributable to n(N)/σ*(P-Cl) hyperconjugation.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2007)
Introduction
P-Functionalised 1,3,2-diazaphospholenes (I) are repre-
sentatives of a class of N-heterocyclic phosphanes that have
recently gained interest because of their unique reactivity.
In particular, P–H-substituted compounds (I; X = H) are
selective hydride-transfer reagents that allow reductive hy-
drogenation of element halides as well as aldehydes and aryl
ketones,[1] and phosphanyl derivatives (I; X = PRЈ2) react
with alkenes and alkynes by diphosphination to give novel
unsymmetrical 1,2-bisphosphanes.[2] This unique reactivity
has, in both cases, been explained by a weakening and con-
comitant ionic polarisation of the P–X bonds which can be
expressed in terms of bond/no-bond resonance between the
canonical structures IЈ and IЈЈ (Scheme 1).[3] The high
weight of the ionic canonical structure IЈЈ is intimately con-
nected with the exceptional stability of the corresponding
phosphenium ions II,[4] which are isoelectronic with imid-
azoyl carbenes III[5] and are stabilised by similar electronic
factors.
Another type of functional 1,3,2-diazaphospholenes,
namely P-chloro-substituted compounds (I; X = Cl),[4,6,7]
are of interest not only from a synthetic point of view as
precursors for the cations II and the aforementioned P–H
and P-phosphanyl derivatives but they also provide evi-
dence for the weakening and enhanced ionic polarisation of
the exocyclic P–Cl bonds.[3] Despite the high intrinsic po-
larity of these bonds, these phenomena still exert a visible
effect on the chemical reactivity and have, for example, been
Scheme 1.
considered as crucial for the use of P-chlorodiazaphosphol-
enes as organocatalysts in the P–C cross-coupling between
alkyl chlorides and trimethylsilyl diphenylphosphane.[8] The
P–Cl bond lengthening is also significant from a structural
point of view and it has been argued that its occurrence is
attributable to a high degree of aromatic stabilisation in the
heterocyclic ring, which induces a concomitant spontane-
ous dissociation of the P–Cl bond.[4,7] Although this in-
terpretation was subsequently discredited,[3] a precise analy-
sis of the bonding situation in P-chlorodiazaphospholenes
is still needed.
During our investigations of the chemistry of N-hetero-
cyclic phosphanes we have developed a general synthetic
method for the preparation of 2-chloro-1,3,2-diazaphos-
pholenes and 1,3,2-diazaphospholenium ions with a wide
range of substituent patterns.[1] In this work we will give a
full account of this synthetic work, and we will report on
the interpretation of trends in structural parameters which
were obtained from X-ray diffraction studies on a compre-
hensive series of these compounds.
[a] Institut für Anorganische Chemie, Universität Stuttgart,
Pfaffenwaldring 55, 70550 Stuttgart, Germany
Fax: +49-711-685-64241
Results and Discussion
E-mail: gudat@iac.uni-stuttgart.de
Syntheses and Spectroscopic Studies
[b] VTT Technical Research Centre of Finland,
P. O. Box 1300, Tampere, Finland
Known synthetic routes to 2-chloro-1,3,2-diazaphos-
pholenes (I; X = Cl) include base-induced condensations of
[c] Laboratory of Inorganic Chemistry, University of Helsinki,
A. I. Virtasen aukio 1, Helsinki, Finland
5112
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 5112–5119

2-Chloro-1,3,2-diazaphospholenes
PCl3 with 1,4-diazabutadienes,[6] salt-elimination reactions scopic data) has been given elsewhere[3] and is not repeated
of PCl3 with 1,4-diazabutadienide dianions[7] or metathesis here. Methylation in the 4,5-positions of the diazaphospho-
reactions of PCl3 with 1,3,2-diazasiloles.[4] The products can lene ring induces a deshielding of the 31P NMR signals of
be converted into diazaphospholenium salts by subsequent 3d,e by some 15 ppm with respect to 3a,c. As expected,
treatment with Lewis acids such as AlCl3, GaCl3, SbCl5 or both the 31P and the 13C NMR signals of the ring carbon
Me3SiOTf.[3,4,9] It was shown recently that triiodide or atoms in the 1,3,2-diazaphospholenium salts 4b,c and 5f are
pentachlorostannate(IV) salts of cations II are also access- deshielded with respect to the appropriate signals in the
ible in one step by a redox reaction between a diazabutadi- neutral precursors 3b,c,f. The salt 4b exhibits the largest 31
ene and PI3 or a mixture of PCl3 and SnCl2, respectively.[10] NMR shift for a 1,3,2-diazaphospholenium cation observed
P
31P
The limitations of the existing methods are that their appli- so far (δ = 209.4 ppm).
cation may be restricted to the synthesis of heterocycles
with specific substitution patterns, the yields of products
may be low owing to the occurrence of side reactions or
difficulties in purifying the products or intermediates, or
Crystal Structure Studies
that the possible redox activity of counter anions such as
–
–
I3 or SnCl5 may limit the use of the product in further
transformations. In order to circumvent these restrictions
we have developed a simple protocol for the preparation of
2-chloro-1,3,2-diazaphospholenes starting from N-arylated
1,4-diazabutadienes.[1] We demonstrate here that the same
procedure is also applicable for the synthesis of N-alkylated
and C-alkylated heterocyclic rings.
Suitable crystals for single-crystal X-ray diffraction stud-
ies of the 1,3,2-diazaphospholenes 3b–h and the 1,3,2-diaza-
phospholenium salts 4b,c,g and 5f were obtained by crystal-
lisation of appropriate solutions at low temperature (see
Scheme 2 and Exp. Sect. for further details). The salt 5f
crystallised as a solvate with one molecule of CH2Cl2 per
formula unit.
The novel P-chlorodiazaphospholenes 3b,h and 3d–f are
accessible in a similar way as the previously reported deriva-
tives 3a,c,g[1] in a cascade reaction involving reduction of
the readily available 1,4-diazabutadienes 1a–h with excess
lithium, quenching the resulting dianions with triethylamine
hydrochloride at –78 °C, and condensation of the products
formed with PCl3 at the same temperature. All subsequent
reaction steps can be carried out in a one-pot procedure
without isolation of any intermediates. The triethylamine
introduced to protonate the diazadienide dianions is reused
to scavenge the hydrogen chloride liberated in the last step.
As reported earlier,[9,11] protonation of the diazadienide di-
anions yields either α-aminoaldimines 2a–c,g,h or 2,3-di-
amino-2-butenes 2d–f depending on whether the central
carbon atoms in the dianions bear hydrogen or alkyl sub-
stituents, respectively; both types of intermediates can be
isolated as stable compounds if desired. The 2-chloro-1,3,2-
diazaphospholenes 3b,d–f,h were isolated as off-white to
orange, moderately moisture-sensitive solids in good to ex-
cellent yields of 75–92% after work up. Reports of 4,5-dial-
kylated 1,3,2-diazaphospholenes are rare, although some
derivatives have been obtained by condensation of a diami-
noethene with substituted phosphorus dihalides according
to a similar reaction to that reported here.[12]
Compounds 3b,c,g were converted into the 1,3,2-diaza-
phospholenium salts 4b,c,g by treatment with Me3SiOTf by
analogy to a previously reported method,[3] In a similar
manner, 5f was obtained by treatment of 3f with GaCl3.[13]
All phosphenium salts were isolated after work-up as air-
and moisture-sensitive powders in more than 90% yield.
All phosphorus heterocycles prepared were characterised
by analytical data and spectroscopic techniques. The NMR
spectroscopic data of both 2-chloro-1,3,2-diazaphosphol-
enes and phosphenium salts are unremarkable and are sim-
Scheme 2. Synthesis of 2-chloro-1,3,2-diazaphospholenes and
1,3,2-diazaphospholenium salts; (i) 2 Li; (ii) 2 HNEt3Cl, –78 °C;
(iii) PCl3, –78 °C; (iv) Me3SiOTf, –78 °C/–Me3SiCl; (v) GaCl3.
(Mes = 2,4,6-Me3C6H2, DMP = 2,6-Me2C6H3, DIPP = 2,6-
iPr2C6H3).
The molecular structures of the P-chlorodiazaphospho-
ilar to known literature data;[1,3,4,7,10] a discussion of trends lene 3f and the tetrachlorogallate salt 5f are shown in Fig-
in chemical shifts (including 35Cl and 15N NMR spectro- ures 1 and 2, respectively. The tert-butyl moieties in both
Eur. J. Inorg. Chem. 2007, 5112–5119
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5113

D. Gudat et al.
FULL PAPER
N-aryl substituents of 3f are located on the same side of rus and the closest chlorine atom in the anion (3.75 Å) is
the diazaphospholene ring trans to the chlorine substituent, close to the sum of the van der Waals radii (thus ruling
thereby suggesting that the direct steric interaction between out any substantial intermolecular interactions) and both
the tert-butyl groups is lower than the repulsion between nitrogen atoms still display planar coordination geometries
substituents at adjacent ring atoms. Interestingly, the ar- [sum of bond angles of 359.4(6)° for N2 and 359.7(6)° for
rangement of the tert-butyl groups in the cation of salt 5f N5] it can be concluded that the steric strain between the
remains unchanged. As the distance between the phospho- bulky N-aryl substituents is negligible. The preference for
the observed pseudo-Cs-symmetric conformation over a C2-
like conformation with tert-butyl moieties on opposite sides
of the diazaphospholene ring is presumably due to the fact
that it facilitates a closer stacking of molecules in the crys-
tal.
Selected bond lengths and angles of all neutral P-chloro-
diazaphospholenes and the cations of phosphenium salts
are summarised in Table 1 together with the previously re-
ported structural data for 3a,g and 4a[3] for comparison.
The five-membered rings of all P-chlorodiazaphospholenes
feature a similar flat envelope conformation to that already
found for 3a,g,[3] while the rings of the cations display no
significant deviations from planarity. All molecules exhibit
only insignificant deviations between the two crystallo-
graphically independent P-N2/N5 and C3/4-N2/5 distances.
The endocyclic P–N and C–C bond lengths in all studied
2-chloro-1,3,2-diazaphospholenes are similar and match the
values for 3a and 3g. The C–N bonds in 3b and 3h are
likewise similar to those of 3a and 3g while the C-methyl-
ated derivatives 3d–f display a small (1–2 pm) yet crystallo-
graphically significant bond lengthening. The most impor-
tant variation is found for the exocyclic P–Cl bond lengths,
which range from 2.243(1) Å in 3c to 2.692(4) Å in 3g. All
distances are thus considerably longer than standard P–Cl
bonds in diaminochlorophosphanes (2.13Ϯ0.06 Å[14]), al-
though the bond length in 3c, which is the shortest P–Cl
bond in a 2-chloro-1,3,2-diazaphospholene reported to
date, comes quite close to the normal range. A comparison
between compounds with N-Mes (3a,d) and N-DIPP (3c,e)
substituents reveals that the P–Cl bonds in the latter are 3–
8 pm shorter, although the reason for this effect is not obvi-
ous. The longest P–Cl bonds are found for the N-alkyl-sub-
stituted compounds 3g,h.
Figure 1. Molecular structure of 3f. Thermal ellipsoids are drawn
at the 50% probability level and H atoms have been omitted for
clarity.
Figure 2. Molecular structure of 5f. Thermal ellipsoids are drawn
at the 50% probability level and H atoms have been omitted for
clarity.
Table 1. Selected bond lengths [Å] and angles [°] for the 2-chloro-1,3,2-diazaphospholenes 3a–h and the cations of the 1,3,2-diazaphosphol-
enium salts 4a–c, 4g, and 5f.
R1
R2
P1–Cl1
P1–N2
P1–N5
N2–C3
N5–C4
C3–C4
N2–P1–N5
3a[a]
3b
Mes
H
H
H
Me
Me
2.324(1)
2.362(1)
2.243(1)
2.354(1)
2.325(1)
2.331(1)
2.692(4)
2.567(1)
–
1.673(1)
1.678(2)
1.684(1)
1.664(2)
1.679(1)
1.671(1)
1.663(1)
1.671(2)
1.666(2)
1.664(1)
1.677(1)
1.658(2)
1.663(2)
1.675(1)
1.675(2)
1.679(1)
1.673(1)
1.674(1)
1.669(1)
1.665(1)
1.669(2)
1.671(1)
1.664(1)
1.675(1)
1.660(2)
1.674(2)
1.406(2)
1.400(2)
1.408(2)
1.427(2)
1.425(2)
1.427(2)
1.391(1)
1.403(3)
1.374(2)
1.373(2)
1.365(2)
1.365(3)
1.386(3)
1.402(2)
1.398(2)
1.402(2)
1.430(2)
1.423(2)
1.422(2)
1.391(1)
1.401(3)
1.378(2)
1.373(2)
1.371(2)
1.368(3)
1.372(3)
1.338(2)
1.335(3)
1.333(2)
1.331(2)
1.345(2)
1.344(2)
1.349(1)
1.339(3)
1.351(2)
1.351(3)
1.356(2)
1.349(4)
1.379(3)
89.7(1)
89.3(1)
89.4(1)
89.9(1)
89.8(1)
89.5(1)
90.6(1)
90.2(1)
89.6(1)
89.5(1)
88.9(1)
90.6(1)
89.1(1)
DMP
DIPP
Mes
DIPP
2-tBu-C6H4 Me
tBu
Cy
Mes
DMP
DIPP
tBu
3c
3d
3e
3f
3g[a]
3h
H
H
H
H
H
H
4a[a]
4b
–
–
–
–
4c
4g
5f[b]
2-tBu-C6H4 Me
[a] Data from ref.[3] [b] Different crystallographic numbering scheme.
5114
www.eurjic.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 5112–5119

2-Chloro-1,3,2-diazaphospholenes
The P–N bond lengths in the cations of the phosphenium
salts 4a–c,g and 5f match the values in 3a–h closely, whereas
the adjacent C–N bonds are approximately 3 pm longer
than in the neutral compounds. The C–C bonds in the cat-
ions are also longer than in 3a–h, although the difference
in this case is less pronounced (approx. 1 pm) and on the
verge of being significant when compared with the magni-
tude of the estimated standard deviations (see data in
Table 1). The cation of 5f is an exception and displays a
significant lengthening of the C–C bond length, which is
possibly influenced by the presence of methyl substituents
at both ring carbon atoms. Apart from this effect, the variation
of bond lengths in the phosphenium cations shows no clear
connection with the changes in the substituent pattern.
The existence of a series of crystal structure analyses of
similar compounds stimulated us to attempt a discussion of
common trends in the sense of a structure correlation. This
principle, which was coined by Bürgi and Dunitz,[15] states
that structural changes that occur during a chemical reac-
tion can be manifested in the ground-state structure as devi-
ations of bond lengths and angles from “normal values”
along the reaction coordinate. In the case of P-chlorodiaza-
phospholenes the extraordinary P–Cl bond lengthening,
which was first reported for 3g, can be interpreted as a con-
sequence of spontaneous bond heterolysis that is energeti-
cally driven by the aromatisation of the cyclic phosphenium
cation fragment.[4,7] Given the validity of this hypothesis,
the application of the structure-correlation principle implies
that a comparison of the crystal structure data of all com-
pounds included in this study might reveal a systematic cor-
relation between the P–Cl bond lengthening, the lengthen-
ing of the C–C double bond, and a concomitant shortening
of the C–N and P–N single bonds, respectively.
Figure 3. Plot of P–Cl distances [Å] vs. average P–N distances [Å]
for 3a–h (diamonds) and for all (R2N)2PCl compounds (except
3a,g) listed in the CSD data base (open squares). The solid and
dashed lines represent the result of linear regression analyses. Error
bars at the data points for 3a–h denote a range of Ϯ3σ, where σ is
the estimated standard deviation. R2 is the square of the correlation
coefficient in the regression analysis.
An analysis of the trends in endocyclic P–N, N–C and
C–C bond lengths in the diazaphospholenes 3a–h and the
salts 4a–c,g and 5f shows that the observed changes are
essentially uncorrelated. A regression analysis of the
changes in P–N and C–N distances for all compounds (Fig-
ure 4) gave a statistical correlation coefficient (r = 0.41)
which suggests no significant connection between both pa-
rameters. Furthermore, a positive slope for the computed
regression curve indicates parallel trends of the lengths of
Inspection of a plot of the P–Cl versus average P–N dis-
tances for the diazaphospholenes 3a–h (Figure 3) reveals
that the P–Cl bond lengthening indeed appears to coincide
with a general shortening of the P–N bonds. A linear re-
gression analysis reveals that this correlation is not particu-
larly strong, and the magnitude of the correlation coeffi-
cient (r = 0.78) implies the presence of some scattering
which suggests that additional factors also have a major
impact on both bond lengths. If one considers that the indi-
vidual compounds are not isostructural but crystallise in
different space groups, and thus exhibit different types of
crystal packing, the observed scattering is presumably due,
at least in part, to variations in intermolecular interactions
(the validity of this assumption is substantiated by the ob-
served difference in P–Cl bond lengths between pure 3g and
its toluene solvate[3]). Even though an analysis of the crys-
tallographic data of all diaminochlorophosphanes of the
type (R2N)2PCl (except 3a,g) listed in the CSD data base
reveals a similar relation between the changes in P–N and
P–Cl bond lengths, the two regression lines deviate substan-
tially from each other (Figure 3). In principle, this finding
underlines, in a quantitative way, the previously mentioned
hypothesis of the P–Cl bond in the N-heterocyclic deriva-
tives 3a–h being much “softer” (i.e. more easily polarisable)
than in diaminochlorophosphanes in general.
Figure 4. Plot of the average P–N distances [Å] vs. average C–N
distances [Å] of 3a–h (diamonds) and 4a–c, 5f (open squares). Error
bars at each data point denote a range of Ϯ3σ, where σ is the
estimated standard deviation.
Eur. J. Inorg. Chem. 2007, 5112–5119
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5115

D. Gudat et al.
FULL PAPER
Figure 5. Plot of the average P–N distances [Å] vs. C–C distances [Å] of 3a–h (diamonds) and 4a–c, 5f (open squares). Error bars at each
data point denote a range of Ϯ3σ, where σ is the estimated standard deviation.
both types of bonds, which is hardly compatible with a con- of 1,4-diazadienes and subsequent condensation with phos-
nection between P–Cl bond dissociation and increasing aro- phorus trichloride offers a generally applicable and econ-
maticity in the ring.[4] A regression analysis of the connec- omic access to 2-chloro-1,3,2-diazaphospholenes with a
tion between changes in P–N and C–C distances (Figure 5) wide range of substituents at both the ring nitrogen and
indicated a statistically still weaker correlation (r = 0.34), carbon atoms. All products were obtained in high yields
the physical interpretation of which is further complicated and purity and are suitable starting materials for further
by the fact that the observed differences in C–C bond transformations.[1,3,16] In particular, subsequent Lewis acid-
lengths are rather small when compared with the estimated induced chloride abstraction permits the synthesis of N-het-
standard deviations of the experimental data. Further re- erocyclic phosphenium cations in overall yields that com-
gression analyses which included only data for neutral di- pare well with those of a recently reported one-step synthe-
azaphospholenes, or involved correlations between P–Cl sis involving the redox reaction between a diazabutadiene
and C–N/C–C bond lengths, gave similar or even lower val- and PI3.[10] Systematic single-crystal X-ray diffraction stud-
ues for the correlation coefficients.
ies have revealed that the P–Cl bond lengths in P-chlorodi-
On the whole, the regression analyses performed suggest azaphospholenes vary between 2.24 and 2.70 Å, with the N-
a weak statistical correlation between P–Cl and P–N dis- alkyl derivatives showing systematically longer bonds than
tances in the diazaphospholenes 3a–h, whereas the varia- the N-aryl derivatives. An analysis of trends in the struc-
tions in the endocyclic N–C and C–C bonds appear to be tural parameters underlines that the P–Cl bonds in diaza-
fairly uncorrelated. In contrast, inspection of Figures 3, 4 phospholenes are more easily polarised than in compounds
and 5 suggests that the data for the neutral compounds 3a– of the type (R2N)2PCl in general, but gives no evidence that
h and the salts 4a–c,g and 5f lie in different regions of the the bond lengthening can be interpreted in terms of the
scatter plots that are more or less well separated owing to onset of spontaneous bond heterolysis driven by an increase
systematic deviations in C–N and (less pronounced) C–C in the aromatic character of the diazaphospholene ring.
bond lengths between both types of compounds. All these This analysis supports the results of earlier experimental
features are very well compatible with the explanation of and computational studies which have explained this effect
the bond lengthening in P-chlorodiazaphospholenes being as being mainly the result of n(N)/σ*(P-Cl) hyperconjuga-
due to n(N)/σ*(P-Cl) hyperconjugation, which has also tion.
been derived from earlier computational and experimental
studies,[3] but do not support the interpretation as begin-
ning P–Cl dissociation driven by increasing aromatic char-
acter of the diazaphospholene ring.
Experimental Section
All manipulations were carried out under argon in flame-dried
glassware. Solvents were dried prior to use according to common
Conclusions
We have shown that the previously reported one-pot
procedures. Compounds 1a–h were synthesised according to litera-
route to 1,3,2-diazaphospholenes by reduction/protonation ture procedures.[17] The synthesis of 3a–h was carried out according
5116
www.eurjic.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 5112–5119

2-Chloro-1,3,2-diazaphospholenes
5
3
to the procedure reported in ref.[1] All other chemicals were pur-
chased from commercial suppliers. NMR Spectra: Bruker Avance
400 (1H: 400.13 MHz; 31P: 161.9 MHz; 13C: 100.4 MHz) at 30 °C;
chemical shifts referred to ext. TMS (1H, 13C) or 85% H3PO4 (Ξ
= 40.480747 MHz, 31P); positive signs of chemical shifts denote
shifts to lower frequencies; coupling constants are given as absolute
values; prefixes i-, o-, m-, p- denote atoms of aryl substituents. MS:
Varian MAT 711, EI, 70 eV. Elemental analysis: Perkin–Elmer
2400CHSN/O analyser. Melting points were determined in sealed
capillaries.
(s, i-C), 137.0 (d, JP,C = 5.5 Hz, p-C), 131.8 (d, JP,C = 10.0 Hz, o-
4
C), 129.7 (d, JP,C = 1.0 Hz, m-CH), 125.8 (m, N-CH), 21.0 (d,
6JP,C = 0.8 Hz, p-CH3), 19.1 (d, JP,C = 1.3 Hz, o-CH3), 11.1 (d,
4
3JP,C = 2.0 Hz, CH3) ppm. 31P{1H} NMR (CDCl3): δ = 165.0 (s)
ppm. MS (EI): m/z (%) 386.2 (21.9) [M]+, 351.2 (100.0) [M – Cl]+,
363.0 (19.2) [M – CH3Cl]+, 305.2 (2.7) [M – C3 H1 0Cl]+.
C22H28ClN2P (386.90): calcd. C 68.30, H 7.29, N 7.24; found C
68.24, H 7.35, N 7.13.
2-Chloro-1,3-bis(diisopropylphenyl)-4,5-dimethyl-1,3,2-diazaphos-
pholene (3e): Crystallisation from dichloromethane at –20 °C;
1-[(2,6-Dimethylphenyl)imino]-2-[(2,6-dimethylphenyl)amino]ethane colourless crystals; yield 8.7 g (93 %); m.p. 204 °C. 1H NMR
3
(2b): Compound 1b (18.5 g, 70 mmol) was dissolved in thf
(200 mL), and lithium turnings (1.1 g, 150 mmol) were added. Af-
ter stirring for 24 h the unreacted lithium was filtered off and the
solution cooled to –78 °C. Triethylamine hydrochloride (15.1 g,
150 mmol) was added and the reaction mixture slowly warmed to
room temperature. After the solution had become colourless all
volatiles were removed in vacuo. The residue was dissolved in n-
hexane (150 mL) and the precipitate filtered off. The solution was
concentrated and the product crystallised at –20 °C. The yellow
needles obtained were filtered off and dried in vacuo. Yield 12.0 g
(CDCl3): δ = 7.45–7.13 (m, 6 H, m/p-CH), 3.14 (sept, JH,H
=
4
6.7 Hz, 4 H, CH), 1.84 (d, JP,H = 0.9 Hz, 6 H, NC-CH3), 1.31 (d,
3JH,H = 6.7 Hz, 12 H, CH3), 1.21 (d, JH,H = 6.7 Hz, 12 H, CH3)
3
ppm. 13C{1H} NMR (CDCl3): δ = 148.9 (d, 4JP,C = 5.0 Hz, m-CH),
2
5
131.0 (d, JP,C = 12.1 Hz, i-C), 129.8 (d, JP,C = 1.5 Hz, p-CH),
129.4 (s, o-C), 128.6 (s, o-C), 125.7 (s; N-C), 125.0 (d, JP, C
1.0 Hz, m-CH), 28.9 (d, JP, C = 1.0 Hz, CH3), 26.1 (d, JP, C
4
=
=
5
5
3
1.3 Hz, CH3), 25.0 (s, CH), 11.9 (d, JP,C = 3.4 Hz, NC-CH3) ppm.
31P{1H} NMR (CDCl3): δ = 157.0 (s) ppm. MS (EI): m/z (%) 470.3
(15.1) [M]+, 435.3 (100.0) [M – Cl]+. C28H40ClN2P (471.07): calcd.
(65%), m.p. 136 °C. 1H NMR (CDCl3): δ = 7.83 (t, 3JH,H = 2.1 Hz, C 71.39, H 8.56, N 5.95; found C 71.30, H 8.64, N 6.14.
1 H, CH=N), 7.25–6.80 (m, 6 H, CH), 5.42 (s, 1 H, NH), 4.15 (d,
1,3-Bis(2-tert-butylphenyl)-2-chloro-4,5-dimethyl-1,3,2-diazaphos-
3JH,H = 2.1 Hz, 2 H, CH2-N), 2.42 (s, 6 H, o-CH3), 2.14 (s, 6 H, o-
pholene (3f): Crystallisation from a mixture of dichloromethane/
CH3) ppm. 13C{1H} NMR (CDCl3): δ = 163.7 (s, CH=N), 150.2
diethyl ether (2:1) at –20 °C; colourless crystals; yield 8.7 g (74%);
(s, i-C), 146.4 (s, i-C), 128.9 (s, m-C), 128.2 (s, o-C), 128.0 (s, m-C),
3
4
m.p. 196 °C. 1H NMR (CDCl3): δ = 7.72 (dd, JH,H = 7.0, JH,H
=
126.8 (s, p-C), 123.8 (s, o-C), 121.3 (s, p-C), 52.9 (s, CH2-N), 19.0
(s, o-CH3), 18.2 (s, o-CH3) ppm.
2.0 Hz, 2 H, CH), 7.53 (dd, 3JH,H = 7.0, 4JH,H = 2.0 Hz, 2 H, CH),
7.35 (dt, JH,H = 7.0, JH,H = 2.4 Hz, 2 H, CH), 7.31 (dt, JH,H
1,4-Bis(2-tert-butylphenyl)-2,3-dimethyl-1,4-diazabuta-2-ene (2f): 7.0, JH,H = 2.4 Hz, 2 H, CH), 1.81 (d, JP,H = 0.5 Hz, 6 H, CH3),
Compound 1f (10.4 g, 30 mmol) was dissolved in thf (300 mL), and
1.37 (s, 18 H, CH3) ppm. 13C{1H} NMR (CDCl3): δ = 147.8 (d,
lithium (0.5 g, 60 mmol) was added. The mixture was stirred for 3JP,C = 6.9 Hz, o-C), 135.0 (d, JP,C = 8.4 Hz, i-C), 134.0 (d, JP,C
3
4
3
=
4
4
2
3
4
5
24 h. The remaining lithium was filtered off, the solution cooled to
–78 °C, and triethylamine hydrochloride (6.1 g, 60 mmol) was
added. The reaction mixture was slowly warmed to room tempera-
ture, and all volatiles were removed in vacuo. The residue was dis-
solved in n-hexane (100 mL) and the insoluble portion filtered off.
The filtrate was concentrated to 30 mL and stored at –20 °C. The
yellow powder formed was filtered off and dried in vacuo. Yield
= 7.9 Hz, o-C), 129.0 (d, JP,C = 1.8 Hz, m-C), 127.8 (d, JP,C
0.8 Hz, p-C), 126.8 (d, JP,C = 1.3 Hz, m-C), 125.8 (d, JP, C
6.6 Hz, N-C), 36.0 [d, JP,C = 1.0 Hz, C(CH3)3], 32.1 (d, JP,C
=
=
=
4
2
4
5
4.1 Hz, CH3), 12.0 (d, JP,C = 3.1 Hz, CH3) ppm. 31P{1H} NMR
(CDCl3): δ = 161.9 (s) ppm. MS (EI): m/z (%) 414.2 (17.2) [M]+,
379.2 (86.2) [M – Cl]+, 174.1 (19.3) [M – C12H16NPCl]+.
C24H32ClN2P (414.96): calcd. C 69.47, H 7.77, N 6.75; found C
68.91, H 7.86, N 6.77.
3
1
3
4
9.4 g (89%). H NMR (CDCl3): δ = 7.27 (dt, JH,H = 7.8, JH,H
=
1.7 Hz, 2 H, CH), 7.12 (dd, 3JH,H = 7.8, 4JH,H = 1.7 Hz, 2 H, CH),
6.83 (dt, JH,H = 7.8, JH,H = 1.7 Hz, 2 H, CH), 6.82 (dd, JH,H
7.8, JH,H = 1.7 Hz, 2 H, CH), 5.29 (s, 2 H, NH), 1.91 (s, 6 H,
CH3), 1.37 (s, 18 H, CH3) ppm. 13C{1H} NMR (CDCl3): δ = 143.2
(s, i-C), 138.0 (s, o-C), 126.7 (s, o-CH), 126.3 (s, m-CH), 122.2 (s,
N-CCH3), 119.9 (s, m-CH), 119.2 (s, p-CH), 34.4 (s, C), 30.0 [s,
C(CH3)3], 15.7 (s, CH3) ppm.
2-Chloro-1,3-dicyclohexyl-1,3,2-diazaphospholene (3h): Crystallisa-
tion from a mixture of n-hexane and thf at –28 °C, colourless crys-
tals; yield 2.46 g (43%), m.p. 148 °C. H NMR (CDCl3): δ = 6.91
3
4
3
=
4
1
(s, 2 H, N-CH), 3.98–3.77 (m, 2 H, CH), 2.40–2.25 (m, 8 H, CH2),
1.97–1.60 (m, 8 H, CH2), 1.51–1.21 (m, 4 H, CH2) ppm. 13C{1H}
2
3
NMR (CDCl3): δ = 116.7 (d, JP,C = 8.0 Hz, N-CH), 53.5 (d, JP,C
4
5
= 11.1 Hz, CH), 29.0 (d, JP,C = 9.3 Hz, CH2), 28.1 (d, JP,C
=
2-Chloro-1,3-bis(2,6-dimethylphenyl)-1,3,2-diazaphospholene (3b):
Crystallisation from acetonitrile at –30 °C; colourless crystals; yield
1.2 Hz, CH2), 19.9 (s, CH2) ppm. 31P{1H} NMR (CDCl3): δ =
176.5 ppm. MS (EI): m/z (%) 286.1 (14.4) [M]+, 251.1 (100.0) [M –
21.2 g (92%); m.p. 184 °C. 1H NMR (CDCl3): δ = 7.18 (m, 6 H, Cl]+, 169.1 (7.7) [M – C6H10Cl]+, 87.0 (44.5) [M – C12H20Cl]+.
m/p-CH), 6.46 (s, 2 H, N-CH), 2.46 (s, 12 H, o-CH3) ppm. 13C{1H}
C14H24ClN2P (286.78): calcd. C 58.71, H 8.45, N 9.79; found C
NMR (CDCl3): δ = 136.9 (d, JP,C = 4.5 Hz, i-C), 129.5 (d, 4JP,C
=
58.55, H 8.62, N 9.65. IR: ν = 1566 (m) cm–1.
2
˜
1.3 Hz, m-C), 128.7 (s, p-C), 128.2 (s, o-C), 120.8 (d, 2JP,C = 8.4 Hz,
1,3-Bis(2,6-dimethylphenyl)-1,3,2-diazaphospholenium Trifluoro-
methanesulfonate (4b): Compound 3b (1.32 g, 4 mmol) was dis-
solved in toluene (50 mL) and cooled to –78 °C. Trimethylsilyl tri-
fluoromethanesulfonate (1.78 g, 8 mmol) was added and the solu-
tion stirred for 2 h. All volatiles were then evaporated in vacuo and
the residue dissolved twice in diethyl ether (15 mL) followed by
N-C), 19.4 (d, JP,C = 2.9 Hz, o-CH3) ppm. 31P{1H} NMR
4
(CDCl3): δ = 149.2 (s) ppm. MS (EI): m/z (%) 330.1 (23.9) [M]+,
295.2 (100.0) [M – Cl]+, 190.1 (27.5) [M – C8H9Cl]+. C18H20ClN2P
(330.80): calcd. C 65.36, H 6.09, N 8.47; found C 64.55, H 6.80, N
7.84.
2-Chloro-1,3-dimesityl-4,5-dimethyl-1,3,2-diazaphospholene (3d): removal of the solvent. The product was dissolved in diethyl ether/
Crystallisation from dichloromethane at –20 °C, colourless crystals;
yield 22.6 g (90%); m.p. 219 °C. H NMR (CDCl3): δ = 6.96 (s, 4
dichloromethane (5 mL/10 mL) and crystallised at –20 °C. The
1
colourless crystals were filtered off and dried in vacuo. Yield 1.26 g
1
H, m-CH), 2.30 (s, 6 H, p-CH3), 2.28 (s, 12 H, o-CH3), 1.82 (d,
(95%); m.p. 236 °C. H NMR (CD3CN): δ = 8.14 (s, 2 H, N-CH),
4JP,H = 1.3 Hz, 6 H, CH3) ppm. 13C{1H} NMR (CDCl3): δ = 138.7 7.53–7.35 (m, 6 H, CH), 2.23 (d, 4JP,H = 0.6 Hz, 12 H, o-CH3) ppm.
Eur. J. Inorg. Chem. 2007, 5112–5119
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5117

D. Gudat et al.
13C{1H} NMR (CD3CN): δ = 137.7 (d, JP,C = 2.5 Hz, o-C), 135.3 C19H20F3N2O3PS (444.41): calcd. C 51.35, H 4.54, N 6.30; found
FULL PAPER
3
2
2
(d, JP,C = 3.6 Hz, i-C), 134.9 (d, JP,C = 6.7 Hz, N-CH), 131.6 (d, C 52.09, H 5.10, N 6.06.
5JP,C = 0.7 Hz, p-C), 129.9 (s, m-C), 17.4 (d, 4JP,C = 1.7 Hz, o-CH3)
ppm. 31P{1H} NMR (CD3CN): δ = 209.4 (s) ppm. MS (EI): m/z
1,3-Bis(2,6-diisopropylphenyl)-1,3,2-diazaphospholenium Trifluoro-
methanesulfonate (4c): A solution of 3c (0.89 g, 2 mmol) in toluene
(%) 444. 0 (20.3) [M] + , 29 5. 1 ( 10 0. 0) [M – CF3 SO3 ]+
.
Table 2. Crystallographic data, structure solution and refinement of 3b–f.
3b
3c
3d
3e
3f
Empirical formula
Formula weight
Temperature [K]
C18H20ClN2P
330.78
123(2)
C26H36ClN2P
442.99
123(2)
C22H28ClN2P
386.88
123(2)
C28H40ClN2P
471.04
173(2)
C24H32ClN2P·CH2Cl2
499.86
123(2)
Crystal system
Space group
a [Å]
b [Å]
c [Å]
monoclinic
P21/c
14.9453(3)
7.2778(2)
16.4943(4)
90
113.926(2)
90
1639.90(7)
4
monoclinic
P21/n
9.7599(2)
10.6976(2)
12.3357(3)
90
92.891(1)
90
1286.30(5)
2
monoclinic
P21/c
7.7200(2)
18.7452(6)
14.4230(4)
90
97.635(2)
90
2068.69(10)
4
monoclinic
P21/c
16.899(4)
10.5903(17)
16.434(3)
90
114.480(13)
90
2676.8(8)
4
triclinic
P1
¯
10.9942(3)
11.0029(2)
12.6859(3)
115.005(2)
97.615(2)
105.485(2)
1286.29(5)
2
α [°]
β [°]
γ [°]
V [Å3]
Z
Dcalcd. [gcm–3
]
1.340
0.328
696
1.144
0.225
476
1.242
0.270
824
1.169
0.220
1016
1.291
0.434
528
Abs. coeff. [mm–1
F(000)
]
Crystal size [mm]
0.60ϫ0.35ϫ0.25 0.50ϫ0.25ϫ0.15 0.40ϫ0.20ϫ0.20 0.65ϫ0.50ϫ0.45 0.60ϫ0.50ϫ0.40
θ range for data collection [°]
Reflections collected
Unique reflections
Rint
2.98–25.03
9610
2881
2.52–24.99
13453
4524
3.05–27.48
13602
4651
2.33–28.01
6664
6444
3.07–27.48
11453
5698
0.0229
0.0354
0.0348
0.0250
0.0279
Data/restraints/parameters
2881/0/203
1.062
4524/1/271
1.044
4651/0/243
0.938
6444/0/304
1.005
5698/0/282
1.058
GOF on F2
R1 [I Ͼ 2σ(I)]
0.0433
0.0257
0.0381
0.0426
0.0328
wR2 (all data)
0.1153
1.240/–0.271
0.0628
0.220/–0.298
0.0906
0.456/–0.304
0.1237
0.496/–0.266
0.0864
0.328/–0.302
Largest diff. map peak/hole [eÅ–3
]
Table 3. Crystallographic data, structure solution and refinement for 3h, 4b,c,g and 5f.
3h
4b
4c
4 g
5f
Empirical formula
Formula weight
C14H24ClN2P
286.77
C19H20F3N2O3PS
444.40
C27H36F3N2O3PS
556.61
C11H20F3N2O3PS
348.32
C24H32Cl4GaN2P
591.01
Temperature [K]
123(2)
123(2)
173(2)
123(2)
123(2)
Crystal system
Space group
a [Å]
b [Å]
c [Å]
triclinic
P1
orthorhombic
Pnma
10.2721(3)
17.4393(8)
11.7441(5)
90
triclinic
P1
orthorhombic
Pnma
12.4780(3)
8.5135(2)
15.3270(4)
90
monoclinic
P21/n
10.1559(2)
9.4609(2)
28.6877(7)
90
98.102(1)
90
2728.92(10)
4
¯
¯
6.995(2)
9.164(2)
12.244(2)
100.67(2)
92.28(2)
98.03(2)
762.0(3)
2
9.875(2)
10.708(2)
14.739(3)
95.172(14)
104.567(15)
100.759(15)
1466.4(5)
2
α [°]
β [°]
90
90
90
90
γ [°]
V [Å3]
Z
2103.82(15)
4
1.403
0.278
920
1628.21(7)
4
1.421
0.337
728
Dcalcd. (gcm–3
)
1.250
0.342
308
1.261
0.214
588
1.439
1.474
1216
Abs. coeff. [mm–1
F(000)
]
Crystal size [mm]
0.40ϫ0.30ϫ0.20
3.10–25.02
8795
2654
0.0510
0.50ϫ0.30ϫ0.15
3.47–27.48
10939
2463
0.0337
0.70ϫ0.35ϫ0.25
1.96–27.50
7127
6731
0.0224
0.40ϫ0.25ϫ0.15
3.12–27.48
9671
1982
0.0406
0.15ϫ0.15ϫ0.15
2.96–27.48
14785
6068
0.0473
θ range for data collection [°]
Reflections collected
Unique reflections
Rint
Data/restraints/parameters
2654/0/163
1.058
2463/0/141
1.017
6731/0/327
1.051
1982/0/115
1.075
6068/0/291
0.918
GOF on F2
R1 [I Ͼ 2σ(I)]
0.0369
0.0357
0.0425
0.0428
0.0358
wR2 (all data)
0.0960
0.338/–0.266
0.0950
0.262/–0.282
0.1131
0.387/–0.378
0.1186
0.484/–0.408
0.0792
0.843/–0.544
Largest diff. map peak/hole [eA–3
]
5118
www.eurjic.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 5112–5119

2-Chloro-1,3,2-diazaphospholenes
(30 mL) was cooled to –78 °C and trimethylsilyl trifluoromethanes-
ulfonate (1.08 g, 5 mmol) was added. After stirring for 2 h at room
temperature all volatiles were evaporated in vacuo and the residue
dissolved twice in 15 mL of diethyl ether, followed by removal of
the solvent. The product was dissolved in a mixture of n-hexane,
toluene, and dichloromethane (5 mL/5 mL/1 mL) and crystallised
at –28 °C. The colourless needles were filtered off and dried in
vacuo. Yield 0.78 g (73%); m.p. 259 °C. 1H NMR (CDCl3): δ =
Acknowledgments
This work was financially supported by the Deutsche Forschungs-
gemeinschaft (DFG).
[1] a) D. Gudat, A. Haghverdi, M. Nieger, Angew. Chem. 2000,
112, 3211–3214; Angew. Chem. Int. Ed. 2000, 39, 3084–3087;
b) S. Burck, D. Gudat, M. Nieger, W.-W. du Mont, J. Am.
Chem. Soc. 2006, 128, 3946–3955.
[2] a) S. Burck, D. Gudat, M. Nieger, Angew. Chem. 2004, 116,
4905–4908; Angew. Chem. Int. Ed. 2004, 43, 4801–4804.
[3] D. Gudat, A. Haghverdi, H. Hupfer, M. Nieger, Chem. Eur. J.
2000, 6, 3414–3425.
[4] M. Denk, S. Gupta, R. Ramachandran, Tetrahedron Lett.
1996, 37, 9025–9028.
[5] A. J. Arduengo III, R. L. Harlow, M. Kline, J. Am. Chem. Soc.
1991, 113, 361–363.
3
3
8.62 (d, JP,H = 0.9 Hz, 2 H, N-CH), 7.64 (t, JH,H = 7.8 Hz, 2 H,
3
3
p-CH), 7.43 (d, JH,H = 7.8 Hz, 4 H, m-CH), 2.50 (sept, JH,H
=
3
6.8 Hz, 4 H, CH), 1.36 (d, JH,H = 6.8 Hz, 12 H, CH3), 1.27 (d,
3JH,H = 6.8 Hz, 12 H, CH3) ppm. 13C{1H} NMR (CDCl3): δ =
2
144.2 (d, JP,C = 3.6 Hz, i-C), 140.2 (s, o-C), 137.1 (s, o-C), 131.5
(d, JP,C = 1.2 Hz, N-CH), 128.3 (s, m-C), 127.5 (s, m-C), 124.6 (s,
2
p-C), 124.2 (s, p-C), 30.9 (s, CH), 30.1 (s, CH), 24.5 (s, CH3), 23.0
(s, CH3), 21.9 (s, CH3), 20.7 (s, CH3) ppm. 31P{1H} NMR (CDCl3):
δ = 205.0 (s) ppm. MS (EI): m/z (%) 556.1 (12.3) [M]+, 407.2 (100.0)
[M – CF3SO3]+. C27H36F3N2O3PS (556.62): calcd. C 58.26, H 6.52,
N 5.03; found C 58.46, H 6.70, N 4.95.
[6] A. M. Kibardin, I. A. Litvinov, V. A. Naumanov, Y. T. Struch-
kov, T. V. Gryaznova, Y. B. Mikhailov, A. N. Pudovik, Dokl.
Akad. Nauk SSSR 1988, 298, 369–372.
1,3-Di-tert-Butyl-1,3,2-diazaphospholenium Trifluoromethanesulfon-
ate (4g): M.p. 168 °C. 1H NMR (CDCl3): δ = 8.17 (s, 2 H, N-CH),
1.69 (d, 4JP,H = 1.8 Hz, 18 H, CH3) ppm. 13C{1H} NMR (CDCl3):
[7] C. J. Carmalt, V. Lomeli, B. G. McBurnett, A. H. Cowley,
Chem. Commun. 1997, 2095–2096.
[8] S. Burck, D. Förster, D. Gudat, Chem. Commun. 2006, 2810–
2812.
[9] a) A. H. Cowley, R. A. Kemp, J. C. Wilburn, Inorg. Chem.
1981, 20, 4289–4293; b) I. A. Litvinov, V. A. Naumov, T. V.
Gryaznova, A. M. Kibardin, A. N. Pudovik, Dokl. Akad. Nauk
SSSR 1990, 324, 623–625.
3
2
δ = 132.9 (d, JP,H = 3.8 Hz N-C), 62.8 (d, JP,H = 7.6 Hz, 1 C),
3
31.4 (d, JP,H = 6.5 Hz, CH3) ppm. 31P{1H} NMR (CDCl3): δ =
205.5. C11H20F3N2O3PS (348.32): calcd. C 36.93, H 5.79, N 8.04;
found C 36.85, H 5.69, N 7.82.
[10] a) G. Reeske, C. R. Hoberg, N. J. Hill, A. H. Cowley, J. Am.
Chem. Soc. 2006, 128, 2800–2801; b) B. D. Ellis, C. L. B. Mac-
donald, Inorg. Chim. Acta 2007, 351, 329–344; c) G. Reeske,
A. H. Cowley, Inorg. Chem. 2007, 46, 1426–1430.
[11] a) T. Gans-Eichler, D. Gudat, M. Nieger, Angew. Chem. 2002,
114, 1966–1969; Angew. Chem. Int. Ed. 2002, 41, 1888–1891;
b) T. Gans-Eichler, D. Gudat, K. Nättinen, M. Nieger, Chem.
Eur. J. 2006, 12, 1162–1173.
[12] a) A. M. Kibardin, T. V. Gryaznova, T. A. Zyablikova, Sh. K.
Latypov, R. Z. Musin, A. N. Pudovik, Zh. Obshch. Khim. 1993,
63, 33–39; b) A. M. Kibardin, T. V. Gryaznova, A. N. Pudovik,
Bull. Acad. Sci. USSR Div. Chem. Sci. (Engl. Transl.) 1987,
36, 1554.
[13] a) A. Dumitrescu, H. Gornitzka, W. W. Schoeller, D. Bouris-
sou, G. Bertrand, Eur. J. Inorg. Chem. 2002, 1953–1956; b) N.
Burford, P. Losier, C. Macdonald, V. Kyrimis, P. K. Bakshi,
T. S. Cameron, Inorg. Chem. 1994, 33, 1434–1439; c) N. Bur-
ford, P. Losier, P. K. Bakshi, T. S. Cameron, J. Chem. Soc. Dal-
ton Trans. 1993, 201–202; d) N. Burford, T. S. Cameron,
J. A. C. Clyburne, K. Eichele, K. N. Robertson, S. Sereda, R. E.
Wasylishen, W. A. Whitla, Inorg. Chem. 1996, 35, 5460–5467.
[14] Average and standard deviation of the result of a query in the
CSD database for P–Cl distances in phosphorus compounds
(R2N)2P–Cl neglecting the entries for 1,3,2-diazaphospholenes.
[15] a) X-ray Analysis and the Structure of Organic Molecules (Ed.:
J. Dunitz), Cornell University Press Ltd., London, 1979; b)
H. B. Bürgi, J. D. Dunitz, Acc. Chem. Res. 1983, 16, 153–161;
c) Structure Correlation (Eds.: H. B. Bürgi, J. D. Dunitz), Ver-
lag Chemie, Weinheim, 1994.
[16] S. Burck, D. Gudat, M. Nieger, J. Tirree, Dalton Trans. 2007,
1891–1897.
[17] a) H. tom Dieck, M. Svoboda, T. Greiser, Z. Naturforsch., Teil
B 1981, 36, 823–832; b) H. A. Zhong, J. A. Labinger, J. E.
Bercaw, J. Am. Chem. Soc. 2002, 124, 1378–1399; c) D. J. Tem-
pel, L. K. Johnson, R. L. Huff, P. S. White, M. Brookhart, J.
Am. Chem. Soc. 2000, 122, 6686–6700.
1,3-Bis(2-tert-butylphenyl)-4,5-dimethyl-1,3,2-diazaphospholenium
Tetrachlorogallate (5f): Compound 3f (207 mg, 0.5 mmol) and gal-
lium trichloride (88 mg, 0.5 mmol) were dissolved in acetonitrile
(10 mL) and stirred for 5 min. Storage of the solution at –35 °C
afforded colourless crystals, which were filtered off and dried in
vacuo. Yield 280 mg (95 %). 1H NMR (CD3CN): δ = 7.84 (dd,
4
3
3JH,H = 8.2, JH,H = 1.6 Hz, 2 H, o -CH), 7.65 (dddd, JH,H = 8.2,
4
6
3JH,H = 7.3, JH,H = 1.6, JP,H = 0.9 Hz, 2 H, m-CH), 7.48 (dddd,
3
4
5
3JH,H = 7.9, JH,H = 7.3, JH,H = 1.6, JP,H = 0.9 Hz, 2 H, p-CH),
3
4
5
7.28 (ddd, JH,H = 7.9, JH,H = 1.6, JH,H = 0.4 Hz, 2 H, mЈ-CH),
4
2.21 (d, JP,H = 1.8 Hz, 6 H, CH3), 1.34 (s, 18 H, CH3) ppm.
13C{1H} NMR (CD3CN): δ = 146.9 (d, JP,C = 3.4 Hz, i-C), 144.6
2
4
(s, o-C), 132.5 (d, JP,C = 1.3 Hz, m-CH), 132.1 (s, m-CH), 132.0
2
(d, JP,C = 5.5 Hz, N-C), 130.9 (s, m-CH), 128.8 (s, p-CH), 37.3 (d,
4JP,C = 0.8 Hz, 1 C), 32.7 (d, JP,C = 2.6 Hz, CH3), 13.8 (d, JP,C
=
5
3
3.9 Hz, CH3) ppm. 31P{1H} NMR (CD3CN): δ = 205.8 (s) ppm.
MS (EI): m/z (%) 379.2 (100.0) [M – GaCl4]+. C24H32Cl4GaN2P
(591.04): calcd. C 48.77, H 5.46, N 4.74; found C 48.49, H 5.39, N
4.74.
Crystal Structure Studies: Single-crystal X-ray diffraction studies
were carried out at low temperatures on a Nonius Kappa-CCD
diffractometer or a Siemens P3 or P4 diffractometer using Mo-Kα
radiation (λ = 0.71073 Å). Direct methods (SHELXS-97[18]) were
used for structure solution and refinement (SHELXL-97,[19] full-
matrix least-squares on F2). An empirical absorption correction
was applied for 5f, and H atoms were refined using a riding model.
The absolute structure of 3c was determined by refinement of
Flack’s x-parameter [x = 0.04(4)].[20] Important data regarding the
data collection and structure solution and refinement are listed in
Tables 2 and 3.
CCDC-650776 (for 3b), -650777 (for 3c), -650778 (for 3d), -650770
(for 3e), -650779 (for 3f), -650780 (for 3h), -650781 (for 4b), -650771
(for 4c), -651156 (for 4g), and -650782 (for 5f) contain the supple-
mentary crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
[18] G. M. Sheldrick, Acta Crystallogr., Sect. A 1990, 46, 467–473.
[19] G. M. Sheldrick, University of Göttingen, Germany, 1997.
[20] H. D. Flack, Acta Crystallogr., Sect. A 1983, 39, 876–881.
Received: June 21, 2007
Published Online: September 20, 2007
Eur. J. Inorg. Chem. 2007, 5112–5119
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5119