π-Indenyl substituted zirconium compounds containing terminal bonded phosphanylphosphido ligands [Ind2Zr(Cl){(Me3Si)P-PR 2-κP1}]. Synthesis, X-ray analysis and NMR studies

Article abstract of DOI:10.1016/j.ica.2012.02.028

Dichloro-bis(indenyl)zirconium(IV) reacts with lithium derivatives of diphosphanes R₂P-P(SiMe₃)Li (R = ^tBu, Et ₂N, ⁱPr₂N) to form complexes with terminal phosphanylphosphido ligands - [Ind₂Zr(Cl)-{(PSiMe₃)P- PR₂-κP¹}]. These compounds are extremely sensitive towards moisture and oxygen. The solid state structures of these complexes were established by single crystal X-ray diffraction. The nitrogen bearing groups R (Et₂N or ⁱPr₂N) significantly lengthen the P-P distances in the related complexes and change the geometry around the phosphido phosphorus in such a way that it becomes less planar.

Full text of DOI:10.1016/j.ica.2012.02.028

Inorganica Chimica Acta 387 (2012) 361–365
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p
-Indenyl substituted zirconium compounds containing terminal bonded
phosphanylphosphido ligands [Ind2Zr(Cl){(Me3Si)P–PR2-
X-ray analysis and NMR studies
j
P1}]. Synthesis,
Agnieszka Łapczuk-Krygier a, Katarzyna Baranowska a, Łukasz Ponikiewski a, Eberhard Matern b,
Jerzy Pikies a,
⇑
a Chemical Faculty, Department of Inorganic Chemistry, Gdansk University of Technology, G. Narutowicza St. 11/12, Pl-80-233 Gdansk, Poland
b Institut für Anorganische Chemie, Universität Karlsruhe (TH), D-76128 Karlsruhe, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
Dichloro-bis(indenyl)zirconium(IV) reacts with lithium derivatives of diphosphanes R2P–P(SiMe3)Li
(R = tBu, Et2N, iPr2N) to form complexes with terminal phosphanylphosphido ligands – [Ind2Zr(Cl)-
Received 16 September 2011
Received in revised form 7 February 2012
Accepted 15 February 2012
Available online 23 February 2012
{(PSiMe3)P-PR2-j
P1}]. These compounds are extremely sensitive towards moisture and oxygen. The solid
state structures of these complexes were established by single crystal X-ray diffraction. The nitrogen
i
bearing groups R (Et2N or Pr2N) significantly lengthen the P–P distances in the related complexes and
change the geometry around the phosphido phosphorus in such a way that it becomes less planar.
Keywords:
P ligands
Ó 2012 Elsevier B.V. All rights reserved.
Phosphido complexes
Zirconium
Indenyl complexes
1. Introduction
[Ind2ZrCl2]. The described results were presented in a preliminary
form at the 18th International Conference on Phosphorus Chemis-
The chemistry of complexes of group 14 metals bearing cyclo-
pentadienyl ligands and one [1–9] or two [1,2,10–16] organyl
phosphido groups is relatively well investigated. The most impor-
tant synthetic route leading to this class of compounds involves
metathesis of the related metallocene dichlorides [Cp2MCl2]
(M = Zr, Hf; Cp = cyclopentadienyl or substituted cyclopentadienyl)
with alkali metal derivatives of primary and secondary phosphanes
with bulky organyl groups. To our surprise, however there have
been no reports on the reactivity of alkali metal derivatives of
phosphanes towards dichloro-bis(indenyl)zirconium(IV).
In the course of our studies upon the reactivity of lithiated
diphosphanes R2P–P(SiMe3)Li towards group 14 dichlorometalloc-
enes, we have established that these compounds can act as precur-
sors for three types of new diphosphorus ligands: terminal
phosphanylphosphinidene R2P–P ligands [17], side-on bonded
phosphanylphosphinidene ligands with a second Cp2ZrCl group
try [20].
2. Discussion
2.1. Reactivity
i
The addition of 1 equiv. of R2P–P(SiMe3)Li (R = Et2N, Pr2N and
tBu) to [Ind2ZrCl2] in toluene or pentane leads to coloured solutions
which contain monosubstituted derivatives [Ind2M(Cl){P(SiMe3)-
PR2-j
P1}] (compounds 1–3) (Scheme 1).
Compound 1 is formed as the sole product, whereas 2 and 3 are
accompanied by some side products. In spite of the increased steric
effect of the
g
5-indenyl ligand the reactivity of [Ind2ZrCl2] towards
R2P–P(SiMe3)Li is comparable to that of [Cp2ZrCl2]. For the
bis(indenyl)Zr(IV) complexes, lower electron densities at the Zr
atoms were estimated compared the related bis(cyclopentadi-
enyl)Zr(IV) derivatives [21]. Thus in the former the nucleophilic
substitution at the Zr atom can be facilitated and it compensates
the greater steric hindrance of indenyl groups.
All these compounds are very well soluble in hydrocarbons and
are very sensitive to moisture and oxygen. The properties of
these compounds depend strongly on the sterical properties of
the group R.
bonded terminally to the phosphinidene phosphorus atom – [
(1,2:2-
-tBu2P = P){Zr(Cl)Cp2}2] [17] and terminal phosphanyl–
phosphido ligands R2P–P(SiMe3) [18,19].
l-
g
In this paper we describe the results of our studies on the reac-
tivity of R2P–P(SiMe3)Li (R = tBu, Et2N, and iPr2N) towards
⇑
Corresponding author. Tel.: +48 58 3472874.
E-mail address: jerzy.pikies@pg.gda.pl (J. Pikies).
0020-1693/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.ica.2012.02.028

362
A. Łapczuk-Krygier et al. / Inorganica Chimica Acta 387 (2012) 361–365
PR2
R = Et2N (1)
[Ind2ZrCl2]
Ind
P
R = iPr2N (2)
R = tBu (3)
+ LiCl
SiMe3
Zr
Ind
R P-P(SiMe )Li
1, 2, 3
Cl
2
3
Scheme 1. Reaction of [Ind2ZrCl2] with R2P-P(SiM3)Li.
Pure 1 is relatively stable in C6D6 solution at ambient tempera-
The data in Table 1 enable us to discuss some factors that influ-
ence the structural features of phosphanylphosphido complexes of
Zr and Hf. The geometries around P2 are pyramidal in all com-
pounds, the geometries around P1 differ considerably.
ture whereas at 50 °C it decomposes completely yielding the re-
lated tetraphosphetane, probably according to the mechanism
published previously [18] (Scheme 2). The stability of crude 1 in
the reaction solution is much higher. Heating of this solution to
50 °C for 5 h caused only a small increase in the intensity of the tet-
raphosphetane signals [18] in 31P{1H} spectrum.
Introduction of amido R groups in 1, 2 and 6 compared to 5
lengthens the P1–P2 distance. This is especially evident for 2
(R = NiPr2). Similar elongation was observed in amido substituted
i
Compound 2 does not react at 50 °C according to Scheme 2 due
to the steric requirements of the NiPr2 and indenyl groups which
prevent the formation of [Ind2Zr(NiPr2)Cl]. However, 2 is not stable
and undergoes significant decomposition after dissolving in tolu-
ene-D8 (see Section 3) under cleavage of the Zr–P bond and the
P–P bond in phosphanylphosphido ligand. To our surprise, 3 is
the least stable of these three compounds. In the reaction solution
we observed only weak signals of 3 (31P NMR spectrum) and iso-
lated 3 decomposes rapidly after dissolving in C6D6 indicating only
diphosphanes [23,24]. The introduction of R = NEt2 in place of Pr
leads to an elongation of the M–P1 distance (1 versus 4 and 6
versus 5), thus it diminishes the M–P1 bond order. It is consistent
with a more pyramidal geometry around P1 in 1 and 6. The dis-
tances M–P and the degree of planarity measured as the sum of
angles around phosphido P atoms in 1 and 6 are very similar to
some classical Zr phosphido complexes bearing relatively volumi-
nous ligands as PHDmp [3], PHTrip [8] and PHCy [9]. Zr
complexes with very voluminous ligands such as P(SiMe3)Mes⁄
[5] and PHMes⁄ [7] display planarity around the P atom, consis-
tent with the relative short Zr–P distances of about 254 pm.
However, compounds 2 (R = NiPr2) and 3 (R = tBu) display high
degrees of planarity around P1 in spite of long Zr–P1 distances.
t
tBu2P–P(SiMe3)H and traces of Bu2PH (31P NMR). In conclusion,
introducing of Ind-groups in place of Cp-groups strongly enhanced
the splitting tendency of the Zr–P bond, and complexes with more
voluminous R groups undergo Zr–P bond cleavage more rapidly
probably due to an overcrowding effect. The side products espe-
cially in the case of 2, (iPr2N)2P–P(SiMe3)H, (iPr2N)2P–P(SiMe3)2
and (iPr2N)2P–P(NiPr2)2 strongly suggest a radical mechanism of
this Zr–P splitting. A similar trend was recently observed in
relatively crowded phosphido hafnium complexes: [Cp⁄CpHf(Me)-
(HPDmp] but not [Cp⁄CpHf(Me)(HPPh] undergo a facile Hf–P bond
cleavage and a formation of DHPDmp [22].
t
The relatively voluminous groups NiPr2 in 2 and Bu in 3 enlarge
the M–P1–P2 angle and thus enlarge the sum of angles around
P1 atoms, but long M–P1 distances suggest single M–P1
bonds.
2.3. 31P NMR studies of phosphanylphosphido complexes of Zr(IV) and
Hf(IV)
2.2. Crystallographic studies of 1–3
The chemical shifts of the phosphido phosphorus P1 and the
phosphanyl phosphorus P2 together with JP1–P2 for all known
1
ꢀ
X-ray structural studies of 1 (triclinic, P1 group, Z = 2), 2 (mono-
clinic, P21/c group, Z = 4) and 3 (monoclinic, P21/c group, Z = 4)
indicate that these complexes display a highly distorted pseudotet-
rahedral geometry around the Zr atoms. The angles (the centre of
Ind1, Zr, the centre of Ind2) are 128.82° for 1, 126.61° for 2 and
128.12° for 3. The angle P1–Zr1–Cl1 is 100.05(3)° for 1, 98.69(9)°
for 2 and 94.96(3)° for 3. The geometries around the metal centres
phosphanylphosphido complexes of Zr and Hf are collected in Ta-
ble 2. For the compounds with known X-ray structures we have
calculated the dihedral angle
the P1–P2 bond.
s of the free electron pairs along
The chemical shifts of the P2 atoms are similar to those ob-
served in related diphosphanes R2P–P(SiMe3)2. The chemical shifts
of the phosphido P1 atoms in Hf complexes are found at higher
field compared to the related Zr complexes. This relationship
seems to be general, see [11,27]. The magnitude of 1JP1–P2 depends
on the steric requirements of R groups but not on the distances P1–
P2. For compounds with less sterically demanding R groups, the
are similar to those of [Cp2Zr(Cl){(Me3Si)P–PiPr2-
[Cp2Hf(Cl){(Me3Si)P–PiPr2-
Si)P–P(NEt2)2-
P1}] (6) [18].
j
P1}] (4) and
j
P1}] (5) [19] and of [Cp2Hf(Cl){(Me3-
j
In 1–3 the indenyl groups are g5 coordinated. The distances
from the centres of the cyclopentadienyl rings of the indenyl
groups (average values) to the Zr atoms are 224.1 pm for 1,
223.8 pm for 2 and 223.4 pm for 3. In 4 the average distance from
the cyclopentadienyl ring centre to the Zr atom is 220.9 pm.
The most important structural features of 1–3 together with re-
lated structural data of 4–6 (for comparison) are collected in
Table 1.
1
absolute values of JP–P are low. In the solid state, the lone pairs
of the P atoms are in a nearly antiperiplanar conformation. Such
conformations may also prevail in solution. In compounds with
more sterically demanding R groups the lone pairs adopt nearly
gauche conformations which leads to the increased absolute values
1
of JP–P
.
SiMe3
Cl
Ind
Ind
Ind
NEt2
Cl
P
P
P
2
NEt2
Zr
Et2N
P
2
P(NEt2)2
SiMe3
Zr
+
Ind
SiMe3
Scheme 2. Thermal decomposition of [Ind2Zr(Cl){P(Me3Si)P-P(NEt2)2}].

A. Łapczuk-Krygier et al. / Inorganica Chimica Acta 387 (2012) 361–365
363
Table 1
Structural data for phosphanylphosphido complexes of zirconium and hafnium (distances [pm], angles [deg]).
Compound
(1)
(2)
(3)
(4) [19]
(5) [18]
(6) [19]a
P1
P1
M
M
P2
P2
M
P2
Si
222.73(8)
265.51(9)
108.15(4)
112.27(4)
100.71(4)
321.13
225.9(2)
262.8(1)
142.28(6)
111.34(4)
97.55(3)
351.17
220.1(1)
265.1(1)
138.82(5)
114.36(5)
93.75(5)
346.93
218.59(14)
258.35(11)
117.58(5)
119.63(5)
111.17(6)
348.37
218.5 (1)
256.81 (9)
117.16(4)
119.37(4)
110.80(5)
347.33
224.7(8)/222.7(9)
264.5(5)/263.2(6)
112.5(3)/115.7(3)
110.9(3)/115.8(3)
99.1(3)/98.5(3)
330.0
P1
P1
P1
Si
P
iP1
iP2
P
311.93
318.5
326.5
313.1
313.1
318.6/316.1
a
Two molecules in the elementary cell.
Table 2
31P NMR data for the phosphanylphosphido complexes of Zr(IV) and Hf(IV).
Compound
P1 [ppm]
P2 [ppm]
1JP1–P2 [Hz]
s
[deg]
Lit.
a
(1)
(6)
(2)
[(Et2N)2P–P(SiMe3)Zr(Cl)Ind2]
[(Et2N)2P–P(SiMe3)Hf(Cl)Cp2]
[(iPr2N)2P–P(SiMe3)Zr(Cl)Ind2]
[(iPr2N)2P–P(SiMe3)Zr(Cl)Cp2]
[(iPr2N)2P–P(SiMe3)Hf(Cl)Cp2]
[iPr2P–P(SiMe3)Zr(Cl)Cp2]
À47.7
–
125.8
–
111.2
116.6
118.7
35.1
35.8
67.44
68.2
250.9
–
172.2
164.6, 160.2
112.7
[18]
a
ꢀ59.8b
ꢀ59.5b
ꢀ7.0b
2.2
541.9
539.6
534.6
428.2
22.6
522.1
520.3
511.5
[25]c
[26]c
[19]
(4)
(5)
(3)
85.0
85.0
99.0
[iPr2P–P(SiMe3)Hf(Cl)Cp2]
[tBu2P–P(SiMe3)Zr(Cl)Ind2]
[tBu2P–P(SiMe3)Zr(Cl)Cp2]
[tBu2P–P(SiMe3)Hf(Cl)Cp2]
À26.0
[19]
a
9.25
À3.0
[19]
[19]
À44.51
67.48
a
b
c
This work.
Very broad doublets.
Not isolated compounds, only 31P NMR data.
3. Experimental
3.1. X-ray
Diffraction data were recorded on a KUMA KM4 diffractometer
with graphite-monochromated MoK radiation using a Sapphire-2
a
CCD detector (Oxford Diffraction Ltd.). The apparatus was
equipped with an open flow thermostat (Oxford Cryosystems).
The structures were solved with direct methods and refined with
the SHELX97 program package [28] with the full-matrix least-
squares refinement based on F2. The data were corrected for
absorption with the CrysAlis RED program [29]. All non-hydrogen
atoms were refined anisotropically. All H atoms were positioned
geometrically and refined using a riding model CAH = 0.95–
0.99 Å and Uiso(H) = 1.2Ueq(C) or 1.5Ueq(C) for CH3 groups.
3.2. NMR
Fig. 1. Molecular structure of
1 showing the atom-numbering scheme (30%
probability displacement ellipsoids), important bond lengths (pm) and bond angles
(deg). H atoms have been omitted. Zr1–Cl1 241.83(9), Zr1–P1 265.51(9), P1–P2
222.73(8), P1–Si1 227.3(1), P1–Zr1–Cl1 100.05(3), Zr1–P1–P2 108.15(4).
31P and 1H NMR spectra were recorded on Bruker AMX300, Bru-
ker AV300 and Bruker AV400 MHz spectrometers (external stan-
dard 85% H3PO4) at ambient temperature. The simulation and
iteration of spectra was made using Bruker software [30]. For the
numbering of atoms see Figs. 1–3.
Me3)Li] [33]. [Ind2ZrCl2] was prepared according to the literature
[34], but with significant modification resulting in the higher yield.
3.3. Syntheses
3.3.1. Synthesis of [Ind2ZrCl2]
31.2 mL of a MeLi solution (1.6 M in Et2O) were added dropwise
at À80 °C to a solution of 6 mL (50 mmol) freshly distilled indene
in THF (20 mL). To the resulting reaction mixture, a suspension
of 5.81 g (25 mmol) ZrCl4 in cold THF (100 mL) was added. The
mixture turned dark red. The solvents were removed in vacuum.
The residue was washed with Et2O and extracted with CH2Cl2.
The extract was evacuated to dryness, the residue washed with
Et2O and then with pentane, finally dried to give an yellow prod-
uct. Yield 5.11 g (52%).
All reactions and manipulations were carried out under the
atmosphere of ultra-high purified argon employing flame-dried
Schlenk type glassware. Solvents were purified, dried and distilled
prior to use from dark blue potassium or sodium diphenyl ketyl
solution. Pentane was dried over Na/benzophenone/diglyme and
distilled under nitrogen. Literature methods were used to prepare
the lithium derivatives of diphosphanes: [(Et2N)2P–P(SiMe3)Li]
[31], [iPr2PP(SiMe3)Li] and [(iPr2N)2P–P(SiMe3)Li] [32], [tBu2PP(Si-

364
A. Łapczuk-Krygier et al. / Inorganica Chimica Acta 387 (2012) 361–365
Anal. Calc. for C29H43N2P2SiClZr (636.38): C, 54.73; H, 6.81; N,
4.40. Found: C, 55.18; H, 6.85; N, 4.14%.
3.3.3. Reaction of (iPr2N)2P–P(SiMe3)Li with [Ind2ZrCl2]. Synthesis of
[Ind2Zr(Cl){(Me3Si)P–P(NiPr2)2- P1}] (2)
j
A suspension of [Ind2ZrCl2] (0.178 g; 0.45 mmol) in toluene
(3 mL) was added to a solution of [(iPr2N)2PP(SiMe3)LiÁ1.1THF]
(0.367 g; 0.88 mmol) in toluene (5 mL) at À44 °C. The mixture
was vigorously stirred and allowed to warm to room temperature.
The suspension dissolved, and the colour of the solution changed to
dark brown. After 1 day the solvents were removed in vacuum.
The residue was dissolved in pentane and filtered. After several
days at À22 °C deep red crystal needles of [(iPr2N)2P–P-SiMe3)Zr(-
Cl)Ind2] (2) deposited (0.080 g, yield 24%). On dissolving 2 in tolu-
ene-d8 a massive decomposition underwent, 2 and additionally
significant amounts of (iPr2N)2P–P(SiMe3)H, (iPr2N)2P–P(SiMe3)2
and (iPr2N)2- P–P(NiPr2)2 as well as small amounts of (iPr2N)2PH,
Fig. 2. Molecular structure of
2 showing the atom-numbering scheme (30%
P(SiMe3)3 and (iPr2N)2P–P( 2-PNiPr2)2PSiMe3 [18] were identified.
l
probability displacement ellipsoids), important bond lengths (pm) and bond angles
(deg). atoms have been omitted. Zr1–Cl1 243.9(1), Zr1–P1 262.8(1), P1–P2
225.9(2), P1–Si1 226.3(3), P1–Zr1–Cl1 98.69(9), Zr1–P1–P2 142.28(6).
The 1H NMR data of 2 were assigned using a 1H-31P HMBC
spectrum.
H
31P{1H} NMR (toluene-d8, ambient temp.): (2) 111.2 ppm (d,
P2), À59.8 ppm (very broad d, P1), 1JP1–P2 = 541.9 Hz. 1H NMR (tol-
uene-d8, ambient temp.): (2) 3.62 ppm (m, NCH(CH3)2), 1.32 ppm
(d, 6.5 Hz, NCH(CH3)2), 0.68 ppm (d, 4.0 Hz, (CH3)3Si).
Anal. Calc. for C33H51N2P2ZrClSi (692.49): C, 57.24; H, 7.42; N,
4.05. Found: C, 55.07; H, 8.49; N, 5.19%.
t
3.3.4. Reaction of Bu2P–P(SiMe3)Li with [Ind2ZrCl2]. Synthesis of
[Ind2Zr(Cl){(Me3Si)P–PtBu2- P1}] (3)
j
A suspension of [Ind2ZrCl2] (0.150 g; 0.38 mmol) in pentane
(3 mL) was added to a suspension of [tBu2PP(SiMe3)LiÁ2THF]
(0.160 g; 0.40 mmol) in pentane (5 mL) at room temperature. The
mixture turned immediately dark red. Lithium chloride was sepa-
rated. The solution was filtered and the volume was reduced to 2/3
under reduced pressure. After 7 days at À22 °C, orange crystals of
[tBu2P–P(SiMe3){Zr(Cl)Ind2] (3) were deposited (0.070 g, yield
29%).
Fig. 3. Molecular structure of
3 showing the atom-numbering scheme (30%
The 31P NMR examination of the reaction solution revealed
probability displacement ellipsoids), important bond lengths (pm) and bond angles
(deg). H atoms have been omitted. Zr1–Cl1 243.39(8), Zr1–P1 265.1(1), P1–P2
220.1(1), P1–Si1 226.0(1), P1–Zr1–Cl1 94.96(3), Zr1–P1–P2 138.82(5).
tBu2P–P(SiMe3)H, tBu2P–P(SiMe3)2, small amounts of 3, tBu2P–P(Si-
Me3)Li and probably
a diphosphorus compound (32.3 and
1
À117.7 ppm, JP–P = À392.7 Hz). Dissolving of 3 in C6D6 leads to
its total decomposition and only tBu2P–P(SiMe3)H and traces of
tBu2PH were found in the resulting solution.
1H NMR (CDCl3): 6.23 ppm (4H, d, J = 3.32 Hz), 6.55 ppm (2H, t,
J = 3.32 Hz), 7.3 ppm (4H, m), 7.6 ppm (4H, m).
31P{1H} NMR (reaction solution, C6D6, ambient temp.): (3)
1
67.2 ppm (d, P2), 9.25 ppm (d, P1), JP1–P2 = 522.1 Hz.
3.3.2. Reaction of (Et2N)2P–P(SiMe3)Li with [Ind2ZrCl2]. Synthesis of
[Ind2Zr(Cl){(Me3Si)P–P(NEt2)2-j
P1}] (1)
Anal. Calc. for C29H41ClP2SiZr (606.35): C, 57.45; H, 6.82. Found:
C, 57.06; H, 6.86%.
A suspension of [Ind2ZrCl2] (0.396 g; 1.01 mmol) in toluene
(3 mL) was added to a solution of [(Et2N)2PP(SiMe3)Li] (0.289 g;
1.01 mmol) in toluene (5 mL) at À40 °C. The mixture was vigor-
ously stirred and allowed to warm to room temperature. The mix-
ture turned dark red and the suspension was dissolved. The next
day, the reaction solution was evaporated in vacuum. The residue
was dissolved in pentane (3 mL), filtrated, and after 2 days at
À22 °C red crystals of 1 were deposited (0.170 g, yield 27%). The
31P NMR examination of the reaction solution detected 1, small
amounts of (Et2N)2P–P(SiMe3)H, (Et2N)2P–P(SiMe3)2 and traces of
Acknowledgements
J.P. and Ł.P. thank the Polish Ministry of Science and Higher
Education (Grant Nr. N N204 271535) for financial support. A.Ł.-
K. thanks the Polish Ministry of Science and Higher Education
(Grant Nr. N N204 145038) for financial support.
the phosphetane Et2NP(
l
2-PSiMe3)2PNEt2 [18].
Appendix A. Supplementary material
31P{1H} NMR (C6D6, ambient temp.): (1) 124.78 ppm (d, P2),
1
À48.83 ppm (d, P1), JP1–P2 = 247.8 Hz. 1H NMR (C6D6, ambient
Supplementary material CCDC 808740, CCDC 808739 and CCDC
808808 contains the crystallographic data for the structures of 1, 2
and 3. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif. Supplementary data associated with this article
can be found, in the online version, at doi:10.1016/j.ica.
2012.02.028.
temp.): (1) 7.70–7.64 ppm (2.0 H, ms, C9H7), 7.15–7.10 ppm (2.0
H, m, C9H7), 6.85–6.86 ppm (6 H, ms, C9H7), 6.42–6.37 ppm (m,
2H, C9H7), 5.43–5.40 ppm (2.0 H, ms, C9H7), 3.35 ppm (4 H, quart
7.0 Hz, d 7.0 Hz, d 14.0 Hz, NCH2CH3), 3.17 ppm (4 H, quart
7.0 Hz, d 14.0 Hz, d 11.4 Hz NCH2CH3), 1.09 ppm (12.8 H, d
7.0 Hz, d 7.0 Hz, NCH2CH3), 0.55 ppm (9H, d, 3.3 Hz, (CH3)3Si).

A. Łapczuk-Krygier et al. / Inorganica Chimica Acta 387 (2012) 361–365
365
[19] R. Grubba, A. Wis´niewska, K. Baranowska, E. Matern, J. Pikies, Polyhedron 30
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