Bis(phosphinimino)methanides as non-innocent ligand in zinc chemistry: Synthesis and structures

Article abstract of DOI:10.1039/c0dt00186d

Reactions of the bis(phosphinimino)methane {CH₂(Ph ₂PNSiMe₃)₂} with the zinc dihalides ZnCl ₂ and ZnI₂ afforded the corresponding bis(phosphinimino) methane complexes [{(Me₃SiNPPh₂)₂CH ₂}ZnCl₂] (1) and [{(Me₃SiNPPh₂) ₂CH₂}ZnI₂] (2). In contrast, treatment of {CH₂(Ph₂PNSiMe₃)₂} with ZnPh ₂ in toluene gave the bis(phosphinimino)methanide complex of [{(Me₃SiNPPh₂)₂CH}ZnPh] (3). Further reaction of 3 with the heterocumulenes di(p-tolyl)carbodiimine and diphenyl ketene resulted via a nucleophilic addition of the methine carbon atom of the {CH(Ph₂PNSiMe₃)₂}^- ligand to the heterocumulenes in a C-C bond formation. New tripodal phenyl zinc complexes of composition [{(Me₃SiNPPh₂)₂CH)(p-Tol)NC-N(p- Tol)}ZnPh] (4) and [{(Me₃SiNPPh₂)₂CH)(Ph ₂CC-O)}ZnPh] (5) were obtained.

Full text of DOI:10.1039/c0dt00186d

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www.rsc.org/dalton | Dalton Transactions
Bis(phosphinimino)methanides as non-innocent ligand in zinc chemistry:
synthesis and structures†
Sebastian Marks,a Tarun K. Pandab and Peter W. Roesky*a
Received 23rd March 2010, Accepted 29th April 2010
First published as an Advance Article on the web 25th June 2010
DOI: 10.1039/c0dt00186d
Reactions of the bis(phosphinimino)methane {CH2(Ph2PNSiMe3)2} with the zinc dihalides ZnCl2 and
ZnI2 afforded the corresponding bis(phosphinimino)methane complexes [{(Me3SiNPPh2)2CH2}ZnCl2]
(1) and [{(Me3SiNPPh2)2CH2}ZnI2] (2). In contrast, treatment of {CH2(Ph2PNSiMe3)2} with ZnPh2 in
toluene gave the bis(phosphinimino)methanide complex of [{(Me3SiNPPh2)2CH}ZnPh] (3). Further
reaction of 3 with the heterocumulenes di(p-tolyl)carbodiimine and diphenyl ketene resulted via a
-
nucleophilic addition of the methine carbon atom of the {CH(Ph2PNSiMe3)2} ligand to the
heterocumulenes in a C–C bond formation. New tripodal phenyl zinc complexes of composition
=
=
[{(Me3SiNPPh2)2CH)(p-Tol)N C–N(p-Tol)}ZnPh] (4) and [{(Me3SiNPPh2)2CH)(Ph2C C–O)}ZnPh]
(5) were obtained.
Westerhausen. It resulted in the trinuclear compound [ClZn{m-
Introduction
(Me3Si)NP(Ph)2}2C]2Zn.35
In the last 20 years, a number of reports were published
dealing with the design and application of amido-metal chem-
istry of the s- and p-block elements and transition metals.1-6
In transition metal chemistry this concept is today sometimes
referred as “post-metallocene” chemistry.7-9 Part of that re-
search is dealing with ligands that contain P–N units such as
phosphoraneiminate (R3PN)-,10-14 phosphinimines (R2PNR¢),15-19
diphosphanylamides (R2PNPR2)- 20-23 and iminophosphonamides
((R2P(NR¢)2)-.24-28 These kinds of compounds were widely used
as ligands in main-group and transition-metal chemistry. In
this context, we and other groups were recently attracted by
In this contribution we now report on the reaction of the neutral
ligand bis(phosphinimino)methane, {CH2(Ph2PNSiMe3)2} with
the zinc halides ZnCl2 and ZnI2 first, followed by a report on
the synthesis of [{(Me3SiNPPh2)2CH}ZnPh]. Finally the reaction
of latter compound with some heterocumulenes is discussed.
Results and discussion
Reaction of {CH2(Ph2PNSiMe3)2} with the zinc dihalides
ZnCl2 and ZnI2 in
a 1 : 1 molar ratio in THF af-
forded the corresponding bis(phosphinimino)methane com-
plexes [{(Me3SiNPPh2)2CH2}ZnCl2] (1) and [{(Me3SiNPPh2)2-
CH2}ZnI2] (2) as colorless crystals in good yields (Scheme 1).
The new complexes have been characterized by standard analyt-
ical/spectroscopic techniques, and the solid-state structures were
established by single-crystal X-ray diffraction.
-
the bis(phosphinimino)methanides ({CH(PPh2NR)2} , R = Mes,
SiMe3) as very useful ligands in coordination chemistry.29-32 In
zinc chemistry the reaction of dimethyl zinc with the neutral
ligand bis(phosphinimino)methane, {CH2(Ph2PNSiMe3)2} was
reported to give [{CH(Ph2PNSiMe3)2}ZnMe].33 The zinc methyl
compounds [{CH(Ph2PNMes)2}ZnMe] and [{CH(Ph2PNPh)-
(Ph2PNMes)}ZnMe] were obtained in a similar way starting
from {CH2(Ph2PNMes)2} and {CH2(Ph2PNPh)(Ph2PNMes)},
respectively.34 Further reactions with alcohols resulted in the
corresponding alkoxy derivatives. These compounds were used as
initiators in ring-opening polymerization catalysis of rac-lactide.
Reaction of [{CH(Ph2PNSiMe3)2}ZnMe] with adamantyl
isocyanate was reported to give a nucleophilic addition of
the methanide carbon to the adamantyl carbon by form-
ing a new C–C bond to yield the tetra-coordinated deriva-
tive [{HC{C(O)N(Ad)}(Ph2PNSiMe3)2}ZnMe].33 Reaction of the
dilithium salt [Li2{C(PPh2NSiMe3)2}]2 with ZnCl2 was studied by
Scheme 1
The NMR data of both complexes point towards a symmetric
coordination of the ligand onto the zinc atom in solution. The sig-
nal of the P–CH2–P protons in the 1H NMR spectrum are split into
a sharp triplet for both compounds. These signals (d 4.20 (1) and
4.25 (2) ppm) are slightly low field shifted compared to the starting
material (d 3.42)36 and to the bis(triphenylsiloxy) zinc complex
[{CH2(Ph2PNC6H2Me3-2,4,6)2}Zn(OSiPh3)2] (d 3.91 ppm).34 The
phenyl region in the 1H NMR spectra is as expected. Compounds
aInstitut fu¨r Anorganische Chemie, Karlsruher Institut fu¨r Technologie
(KIT), Engesserstr., 15, Geb. 30.45, 76131, Karlsruhe, Germany. E-mail:
roesky@kit.edu; Fax: (+49) 721-608-4854; Tel: (+49) 721-608-6117
bDepartment of Chemistry, Indian Institute of Technology Hyderabad,
Yeddumailaram, 502205, Andhra Pradesh, India
1
1 and 2 show sharp signals in the 31P{ H} NMR spectrum
† CCDC reference numbers 770404–770408. For crystallographic data in
CIF or other electronic format see DOI: 10.1039/c0dt00186d
(d 24.6 (1) and 23.4 (2) ppm), which significantly differ from
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the starting material (d -5.9 ppm)36 and [{CH2(Ph2PNC6H2Me3-
2,4,6)2}Zn(OSiPh3)2] (d -16.4 ppm).34
¯
Compound 1 crystallizes in the triclinic space group P1, having
two independent molecules of 1 and three molecules of toluene
in the asymmetric unit (Fig. 1). The bis(phosphinimino)methane
coordinates as a bidentate ligand through the two imine nitrogen
atoms onto the zinc atom forming a six-membered metalla-
cycle (N1–P1–C1–P2–N2–Zn). Although there is no carbon–
zinc contact, the metallacycle adopts a twist boat conformation
presumably due to crystal packing. Thus, the zinc atom is four-
fold coordinated by the bis(phosphinimino)methane ligand and
the two chlorine atoms. The N–Zn–N bite angles of the ligands
inside the bis(phosphinimino)methane moiety are smaller than
in a regular tetrahedron (N1–Zn1–N2 104.86(10)◦ and N3–Zn2–
N4 103.97(10)). The Zn–N bond distances are in the expected
Fig. 2 Solid-state structure of 2 showing the atom labeling scheme,
◦
˚
omitting hydrogen atoms. Selected bond lengths (A) and angles ( ): Zn–N1
2.061(5), Zn–N2 2.033(6), Zn–I1 2.6675(10), Zn–I2 2.5891(9); N1–Zn–N2
107.9(2), N1–Zn–I1 107.7(2), N1–Zn–I2 112.5(2), N2–Zn–I1 105.47(15),
N2–Zn–I2 115.30(14), I1–Zn–I2 107.52(3), P1–C1–P2 120.1(3).
˚
˚
range of Zn1–N1 2.055(3) A, Zn1–N2 2.061(3) A, Zn2–N3
˚
˚
˚
2.064(3) A, Zn2–N4 2.046(2) A (e.g. Zn1–N1 1.980(4) A, and Zn1–
˚
N2 1.955(4) A in N-isopropyl-2-(isopropylamino)troponiminate
zinc methyl).37
Scheme 2
tonated. The new complex has been characterized by standard
analytical/spectroscopic techniques, and the solid-state structure
was established by single-crystal X-ray diffraction (Fig. 3). The
room-temperature 1H and 31P{H} NMR spectra of compound 3
-
show a symmetrical pattern for the {CH(Ph2PNSiMe3)2} ligand.
In the 1H NMR spectrum a significant upfield shift for the P–CH–
P resonance (d 2.07 (3)) is observed compared to the neutral ligand
Fig. 1 Solid-state structure of 1 showing the atom labeling scheme,
omitting hydrogen atoms. One of two independent molecules in the unit
1
(d 3.42).36 Compound 3 shows one signal in the 31P{ H} NMR
◦
˚
cell is shown. Selected bond lengths (A) and angles ( ): Zn1–N1 2.055(3),
spectrum (d 27.1 (3) ppm), which is significantly downfield shifted
compared to the starting material (d -5.9 ppm).36 On the other
hand the analogue mesityl bis(phosphinimino)methanide complex
[{CH(Ph2PNC6H2Me3-2,4,6)2}ZnN(SiMe3)2] shows a signal in the
Zn1–N2 2.061(3), Zn1–Cl1 2.2370(11), Zn1–Cl2 2.3019(11), Zn2–N3
2.064(3), Zn2–N4 2.046(2), Zn2–Cl3 2.2375(11), Zn2–Cl4 2.2909(12);
N1–Zn1–N2 104.86(10), N1–Zn1–Cl1 114.47(8), N1–Zn1–Cl2 106.38(8),
N2–Zn1–Cl1 114.10(8), N2–Zn1–Cl2 107.45(8), Cl1–Zn1–Cl2 109.09(4),
N3–Zn2–Cl3 113.74(7), N3–Zn2–Cl4 108.50(8), N3–Zn2–N4 103.97(10),
N4–Zn2–Cl3 115.73(7), N4–Zn2–Cl4 106.04(8), Cl3–Zn2–Cl4 108.40(4).
1
31P{ H} NMR spectrum in a comparable range (d 33.1 ppm).34
Compound 2 crystallizes in the monoclinic space group P21/c
having four molecules of compound 2 and eight molecules of
THF in the unit cell (Fig. 2). As observed for compound 1
the bis(phosphinimino)methane coordinates as bidentate ligand
with the two imine nitrogen atoms onto the zinc atom. The
thus obtained six-membered metallacycle (N1–P1–C1–P2–N2–
Zn) which shows no carbon–zinc contact adopts a twist boat
conformation. The zinc atom is in the center of a distorted
tetrahedral coordination polyhedron. The observed Zn–N bond
˚
distances are in the expected range of Zn–N1 2.061(5) A and Zn–
˚
N2 2.033(6) A.
In contrast to the reaction of {CH2(Ph2PNSiMe3)2} with
the zinc halides, which resulted in bis(phosphinimino)methane
adducts, treatment of {CH2(Ph2PNSiMe3)2} with ZnPh2 in toluene
gave a bis(phosphinimino)methanide complex of composition
[{(Me3SiNPPh2)2CH}ZnPh] (3) (Scheme 2). During the course
of the reaction the bis(phosphinimino)methane ligand was depro-
Fig. 3 Solid-state structure of 3 showing the atom labeling scheme,
omitting hydrogen atoms. Selected bond lengths (A) and angles ( ): Zn–C1
2.923(2), Zn–C2 1.965(2), Zn–N1 1.9853(13), Zn–N2 2.0298(14), C1–P1
1.728(2), C1–P2 1.716(2); N1–Zn–C2 129.48(8), N2–Zn–C2 125.97(8),
N1–Zn1–N2 104.52(6), P1–C1–P2 124.90(9).
◦
˚
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The solid-state structure of 3 was investigated by single-crystal
X-ray diffraction. The data is in agreement with the NMR data
obtained in solution. Compound 3 crystallizes in the monoclinic
space group P21/c having four molecules in the unit cell. In the
solid state, a pseudo-triangular coordination sphere about the zinc
atom is defined by the two phosphinimine nitrogen atoms and the
carbon atom of the phenyl group. The six-membered metallacycle
formed by the bis(phosphinimino)methanide ligand and the zinc
atom has a twist boat conformation showing Zn–N bond distances
compound 3. In the EI-MS spectrum a molecular peak with low
intensity was detected.
The solid-state structure of compound 4 was established by
single-crystal X-ray diffraction. Compound 4 crystallizes in the
monoclinic space group P21/c with four molecules in the unit
cell. The solid-state structure of compound 4 (Fig. 4) is consistent
with the NMR data obtained in solution. The zinc atom, which
is four-fold coordinated by the three nitrogen atoms of the
new tripodal ligand and the phenyl group, is in the center of
a distorted tetrahedron. The bond distance of the zinc atom
˚
˚
of Zn–N1 1.9853(13) A and Zn–N2 2.0298(14) A. A comparison
of the Zn–C bond distances clearly indicates that the bonding of
˚
to the phenyl group (Zn–C2 2.010(3) A) is in the range of
˚
˚
the zinc atom to the phenyl group (Zn–C2 1.965(2) A) is much
the starting material group (Zn–C2 1.965(2) A). The Zn–N
˚
tighter than to the methanide carbon atom (Zn–C1 2.923(2) A).
bonds of the former bis(phosphinimino)methanide ligand (Zn–
˚
˚
˚
It is established that zinc alkyl compounds react with carbodi-
imides in an insertion reaction into the metal–carbon bond.5,38,39
On the other hand the reaction of [{CH(Ph2PNSiMe3)2}ZnMe]
N1 2.107(2) A and Zn–N2 2.126(2) A) are about 0.1 A longer
than in compound 3, whereas the newly formed Zn–N3 bond
˚
(2.070(2) A) is slightly shorter. Due to the modification of the
with adamantyl isocyanate resulted in an insertion of the ligand
ligand the N1–Zn–N2 angle (93.72(9)◦) is reduced about 11◦ in
33
=
backbone into the C N bond. Therefore we were interested to
comparison to compound 3. The newly formed C–C bond in the
ligand backbone has the expected value of C1–C8 1.536(4) A. As
a result of the reduction of one of the two imine functions of the
former DTC molecule the C–N bond distances vary significantly
(C8–N3 1.361(3) A and C8–N4 1.284(4) A). The reduction also
has an influence onto the bis(phosphinimino)methanide ligand
moiety. In the bis(phosphinimino)methanide ligand a considerable
delocalization of the negative charge throughout the ligand
backbone is observed. This results in short endocyclic P–C bond
distances, e.g. C1–P1 1.728(2) A and C1–P2 1.716(2) A (3). As
a result of the addition reaction which led to compound 4, the
delocalization is removed, leading to elongated C–P bond lengths
˚
study the reactivity of compound 3 with the heterocumulenes di(p-
tolyl)carbodiimine (DTC) and diphenyl ketene.
Reaction of compound 3 with DTC in toluene resulted at
room temperature after workup in a yellow crystalline solid of
˚
˚
=
composition [{(Me3SiNPPh2)2CH)(p-Tol)N C–N(p-Tol)}ZnPh]
(4) (Scheme 3). Obviously there was no reaction of the phenyl
-
group, but the methine carbon atom of the {CH(Ph2PNSiMe3)2}
ligand underwent a nucleophilic addition to the carbodiimine
instead, resulting in a C–C bond formation. As a result of this
reaction a new kind of mono-anionic tripodal N-donor ligand
was formed. The modification of the ligand is clearly seen in
the NMR spectra. The signal of the CH group of the newly
formed bridgehead of the ligand shows in the 1H NMR spectrum
a characteristic triplet (d 4.40 ppm), which is about 2.3 ppm
downfield shifted in comparison to compound 3 but is in the
range of the P–CH2–P group of compounds 1 and 2. A similar
˚
˚
˚
˚
(C1–P1 1.853(3) A and C1–P2 1.844(3) A) and a reduced P1–C1–
P2 bond angle of 114.89(15)◦ (124.90(9)◦ in 3).
1
tendency is observed in the 13C{ H} NMR spectra. The signal of
the carbon bridgehead (d 44.2 ppm) is about 15 ppm downfield
shifted compared to compound 3. For the methyl groups of the
p-tolyl moiety two singlets are seen in the 1H NMR (d 2.13 ppm
1
and 2.34 ppm) and in the 13C{ H} NMR spectrum (d 19.8 ppm
1
and 20.3 ppm) each. In the 31P{ H} NMR spectrum one signal was
detected at d 24.8 ppm, which is slightly shifted in comparison to
Fig. 4 Solid-state structure of 4 showing the atom labeling scheme,
◦
˚
omitting hydrogen atoms. Selected bond lengths (A) and angles ( ):
Zn–C2 2.010(3), Zn–N1 2.107(2), Zn–N2 2.126(2), Zn–N3 2.070(2),
C1–C8 1.536(4), C1–P1 1.853(3), C1–P2 1.844(3), N1–P1 1.582(2),
N2–P2 1.574(2), C8–N3 1.361(3), C8–N4 1.284(4); C2–Zn–N1 126.63(12),
C2–Zn–N2 116.47(10), C2–Zn–N3 117.37(11), N1–Zn–N2 93.72(9),
N1–Zn–N3 96.64(9), N2–Zn–N3 100.69(9), P1–C1–P2 114.89(15),
N1–P1–C1 111.12(12), N2–P2–C1 109.71(12), C1–C8–N3 111.9(2),
C1–C8–N4 122.3(2), N3–C8–N4 125.8(2), C8–N3–Zn 120.50(2).
Next, we studied the reaction of compound 3 with another
heteroallene to get a better insight into the reactivity of this
compound. Treatment of compound 3 with diphenyl ketene40
resulted in the nucleophilic addition of the methine carbon atom
onto the carbonyl carbon atom of the diphenyl ketene molecule.
Scheme 3
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reactions and thus acts as innocent ligand.42 In contrast, in
zinc chemistry derivations of the bis(phosphinimino)methanide
ligand are observed.43 New kinds of compounds were obtained
by a nucleophilic addition of the methine carbon atom of the
=
The obtained product [{(Me3SiNPPh2)2CH)(Ph2C C–O)}ZnPh]
(5) was isolated as yellow crystalline solid (Scheme 3). During
the course of reaction a new tripodal N,N¢,O ligand was formed,
in which the ketene was transformed into an enol. As observed
-
1
{CH(Ph2PNSiMe3)2} ligand to heterocumulenes.
in compound 4 the H NMR signal of the bridgehead carbon
group is about 1.5 ppm downfield shifted to d 3.64 ppm in
comparison to compound 3. In contrast to compounds 1, 2 and
4 this shift is less significant. The shift of signals of the phenyl
Experimental
region are less significant. More characteristic is the 13C{ H}
1
General considerations
NMR spectrum. A weak triplet is observed for the bridgehead
carbon atom (d 47.8 ppm). Other characteristic signals are seen
at d 114.9 ppm for the Ph2C carbon atom and at d 160.0 ppm for
All manipulations of air-sensitive materials were performed with
the rigorous exclusion of oxygen and moisture in Schlenk-type
glassware either on a dual manifold Schlenk line, interfaced to
a high vacuum (10-3 torr) line, or in an argon-filled MBraun
glove box. THF was distilled under nitrogen from potassium
benzophenone ketyl prior to use. Hydrocarbon solvents (toluene
and n-pentane) were dried using an MBraun solvent purification
system (SPS-800). All solvents for vacuum line manipulations
were stored in vacuo over LiAlH4 in resealable flasks. Deuterated
solvents were obtained from Aldrich (99 atom% D). NMR
spectra were recorded on Jeol JNM-LA 400 FT-NMR, a Bruker
Avance 400 MHz NMR or a Bruker Avance II 300 MHz NMR
spectrometer. Chemical shifts are referenced to internal solvent
resonances and are reported relative to tetramethylsilane and
85% phosphoric acid (31P NMR), respectively. IR spectra were
performed on a Bruker IFS 113v. Mass spectra were recorded at
70 eV on Varian Mat SM 11(Finnigan MAT 8200). Elemental
analyses were carried out with an Elementar vario EL or EL
the C–O group. In the 31P{ H} NMR the expected resonance was
1
detected at d 25.3 ppm. In the EI-MS spectrum a weak molecular
peak was measured.
The solid-state structure of compound 5 was established by
single-crystal X-ray diffraction (Fig. 5). Compound 5 crystallizes
in the monoclinic space group P21/c with four molecules of the
complex and four molecules of THF in the unit cell. The solid-state
structure is in agreement with the data obtained in solution. The
zinc atom is distorted tetrahedral coordinated by the phenyl group
and the two nitrogen atoms and the oxygen atom of the newly
formed tripodal ligand. As a result of the ligand transformation,
˚
˚
the Zn–N bond distances (Zn–N1 2.069(2) A, Zn–N2 2.093(3) A)
are a bit longer than in the starting material 3 (Zn–N1 1.9853(13) A
˚
◦
˚
and Zn–N2 2.0298(14) A). The N1–Zn–N2 bite angle of 99.26(10)
is about 5◦ reduced in comparison to compound 3 (N1–Zn1–N2
◦
˚
104.52(6) ). The Zn–O bond distance (Zn–O1 2.024(2) A) is in
the expected range. An enolate type structure of the newly formed
ligand is observed. The bond distances of O1–C38 1.314(4) A
36
III. {(Me3SiNPPh2)2CH2} and diphenylketene40 were prepared
according to literature procedures.
˚
˚
and C38–C39 1.373(4) A are in the range of other zinc enolate
[{(Me3SiNPPh2)2CH2}ZnCl2] (1). ZnCl2 (61 mg, 0.45 mmol)
and [CH2(PPh2NSiMe3)2] (250 mg, 0.45 mmol) were dissolved
in 10 ml of THF at room temperature. After 5 min a colorless
precipitate was formed. The mixture was stirred for another 5 min
and then heated to reflux to obtain a colorless crystalline solid.
The product was collected by filtration, washed with 5 ml of
n-pentane and dried in vacuum. Yield: 295 mg (95%). Single
crystals suitable for X-ray analysis were obtained from hot toluene.
1H NMR (C6D6, 400 MHz): d 0.02 (s, 18 H, SiMe3), 4.20
41
=
complexes, e.g. [BrZn{OC( CH2)Mes}(DMF)].
2
(t, 2 H, P–CH2–P, JH–P = 13.3 Hz), 7.34–7.40 (m, 8 H, Ph),
1
7.45–7.50 (m, 4 H, Ph), 7.80–7.88 (m, 8 H, Ph). 31P{ H}
NMR (C6D6, 161 MHz): d 24.5 ppm. EI-MS (70 eV): m/z
(%) = 658 ([M - HCl]+, rel. int. 32), 569 ([C28H30NP2SiZnCl]+,
18), 543 ([C30H36N2P2Si2]+, 61), 471 ([C28H31NP2Si]+, 100), 456
([C27H28NP2Si]+, 97). C31H40Cl2N2P2Si2Zn·3/2C7H8 (695.10 +
138.21): calc. C 59.82, H 6.30, N 3.36; found: C 59.26, H 6.68
N 3.74%.
Fig. 5 Solid-state structure of 5 showing the atom labeling scheme, omit-
◦
˚
ting hydrogen atoms. Selected bond lengths (A) and angles ( ): Zn–C32
1.985(3), Zn–N1 2.069(2), Zn–N2 2.093(3), Zn–O1 2.024(2), C1–P1
1.850(3), C1–P2 1.847(3), N1–P1 1.576(3), N2–P2 1.584(3), O1–C38
1.314(4), C38–C39 1.373(4); C32–Zn–N1 125.07(11), C32–Zn–N2
122.90(12), C32–Zn–O1 111.42(11), N1–Zn–N2 99.26(10), N1–Zn–O1
95.18(9), N2–Zn–O1 96.37(10), P1–C1–P2 114.4(2), C39–C38–O1
126.3(3), C1–C38–O1 113.4(3), C38–O1–Zn 122.6(2).
[{(Me3SiNPPh2)2CH2}ZnI2] (2). ZnI2 (142 mg, 0.45 mmol)
and [CH2(PPh2NSiMe3)2] (250 mg, 0.45 mmol) were dissolved
in 10 ml of THF at room temperature. After 5 min a colorless
precipitate was formed. The mixture was stirred for another 5 min
and then heated to reflux to obtain colorless needles suitable for
X-ray analysis. The product was collected by filtration, washed
with 5 ml of n-pentane and dried in vacuum. Yield: 361 mg (92%).
1H NMR (d8-THF, 400 MHz): d 0.12 (s, 18 H, SiMe3), 4.25 (t,
2 H, P–CH2P), 7.36–7.41 (m, 8 H, Ph), 7.48–7.53 (m, 4 H, Ph),
Conclusions
1
In bis(phosphinimino)methanide complexes of the main group
and transition metals the ligand is usually not involved in any
7.84–7.89 (m, 8 H, Ph) ppm. 31P{ H} NMR (d8-THF, 161 MHz):
d 23.2 ppm. EI-MS (70 eV): m/z (%) = 748 ([M - HI]+, rel. int.
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73), 661 ([C28H30NP2SiZnI]+, 25), 543 ([C30H36N2P2Si2]+, 100), 471
([C28H31NP2Si]+, 66), 456 ([C27H28NP2Si]+, 98). C31H40I2N2P2Si2Zn
(878.00): calc. C 42.41, H 4.59, N 3.19; found: C 42.41, H 4.64 N
3.01%.
1H NMR (d8-THF, 300 MHz): d -0.17 (s, 18 H, SiMe3), 3.64
2
(t, 1 H, P–CH–P, JH–P = 8.9 Hz), 6.91 (t, 2 H, Ph), 7.03–7.34
(m, 23 H, Ph), 7.44–7.49 (m, 2 H, Ph), 7.82–7.95 (m, 6 H, Ph),
1
8.17–8.20 (m, 2 H, Ph) ppm. 13C{ H} NMR (d8-THF, 75 MHz):
d 4.1 (t, SiMe3), 47.8 (t, P–C–P, 1JC–P = 66.9 Hz), 114.9 (t, CPh2),
123.1 (Ph), 125.8 (Ph), 126.6 (Ph), 127.5 (Ph), 128.1–129.5 (m,
Ph), 132.8–135.0 (m, Ph), 141.0 (Ph), 143.7 (Ph), 145.6 (Ph), 154.1
[{(Me3SiNPPh2)2CH}ZnPh] (3). ZnPh2 (200 mg, 0.91 mmol)
and [CH2(PPh2NSiMe3)2] (510 mg, 0.91 mmol) were dissolved in
5 ml of toluene at room temperature. The mixture was stirred
for 16 h. The volatiles were evaporated in vacuum to leave a
foamy residue. Upon washing with n-pentane (5 ml) a pale yellow
crystalline solid was formed and single crystals suitable for X-ray
analysis could be obtained. Yield: 480 mg (76%).
1
(Ph), 160.0 (t, C–O) ppm. 31P{ H} NMR (d8-THF, 121 MHz):
d 25.3 ppm. EI-MS (70 eV): m/z (%) = 892 ([M]+, 6), 647
([M - DPK - C4H4]+, 100), 621 ([M - DPK - Ph]+, 51), 558
([CH2(PPh2NSiMe3)2]+, 92), 543 ([CH2(PPh2NSiMe3)2 - Me]+,
100), 455 ([CH2(PPh2)(PPh2NSiMe2)]+, 100), 193 ([DPK]+, 88).
C51H54N2OP2Si2Zn (894.52): calc. C 68.48, H 6.08, N 3.13; found
C 67.84, H 6.23, N 2.74%.
1H NMR (C6D6, 400 MHz): d 0.15 (s, 18 H, SiMe3), 2.07 (t,
1 H, P–CH–P), 6.95–7.01 (m, 12 H, o-, p-PPh), 7.28–7.32 (m,
1 H, Zn–o-Ph), 7.44–7.48 (m, 2 H, Zn–p-Ph), 7.61–7.67 (m, 8
1
H, m-PPh), 8.13–8.15 (m, 2 H, Zn–m-Ph) ppm. 13C{ H} NMR
X-Ray crystallographic studies of 1–5
(C6D6, 100 MHz): d 3.8 (t, SiMe3), 29.2 (t, P–CH–P), 126.5 (Zn–
o-Ph), 127.6 (Zn–p-Ph), 128.1 (m, o-PPh), 130.5 (p-PPh), 131.7
(m, m-PPh), 137.5 (dd, i-PPh), 139.5 (Zn–m-Ph), 154.9 (Zn–i-Ph)
A suitable crystal was covered in mineral oil (Aldrich) and
mounted onto a glass fiber. The crystal was transferred directly
to the -73 ◦C cold N2 stream of a Stoe IPDS 2 or Stoe IPDS
2T. Subsequent computations were carried out on an Intel Pentium
Core2Duo PC.
1
ppm. 31P{ H} NMR (C6D6, 161 MHz): d 27.1 ppm. IR (cm-1):
3048 (m), 2946 (m), 1433 (m), 1267 (s), 1241 (m), 1178 (w), 1102
(m), 1060 (m), 956 (w), 828 (s), 741 (s), 693 (s), 497 (s). EI-MS
(70 eV): m/z (%) = 698 ([M]+, 35), 621 ([M - Ph]+, 80), 558
([CH(PPh2NSiMe3)2]+, 88), 543 ([CH(PPh2NSiMe3)2 - Me]+, 100),
455 ([CH(PPh2)(PPh2NSiMe2)]+, 48). C37H44N2P2Si2Zn (700.29):
calc. C 63.46, H 6.33, N 4.00; found: C 62.77, H 6.27, N 3.70%.
All structures were solved by the Patterson method (SHELXS-
97).44 The remaining non-hydrogen atoms were located from
successive difference Fourier map calculations. The refinements
were carried out by using full-matrix least-squares techniques on
F2, minimizing the function (Fo - Fc)2, where the weight is defined
as 4Fo2/2(Fo2) and Fo and Fc are the observed and calculated
structure factor amplitudes using the program SHELXL-97.44
Carbon-bound hydrogen atom positions were calculated and
allowed to ride on the carbon atoms to which they are bonded. The
hydrogen atom contributions of compounds 1–5 were calculated,
but not refined. The locations of the largest peaks in the final
difference Fourier map calculation as well as the magnitude of
the residual electron densities in each case were of no chemical
significance.
=
[{(Me3SiNPPh2)2CH(p-tol)N C–N(p-tol)}ZnPh] (4). A solu-
tion of [{(Me3SiNPPh2)2CH}ZnPh] (200 mg, 0.28 mmol) in
5 ml of toluene was added to a stirred suspension of di(p-
tolyl)carbodiimine (65 mg, 0.28 mmol) in 5 ml of toluene at
ambient temperature. After 5 min the suspension became a pale
yellow solution. Stirring was continued for 2 h. The reaction
mixture was then filtered and concentrated. Pale yellow single
crystals suitable for X-ray analysis could be obtained from hot
toluene. Yield: 120 mg (46%).
1H NMR (d8-THF, 300 MHz): d -0.16 (s, 18 H, SiMe3), 2.13
(s, 3 H, NamidePhMe), 2.34 (s, 3 H, NiminePhMe), 4.40 (t, 1 H,
2
Crystal data for 1. 2(C31H40Cl2N2P2Si2Zn)·3(C7H8), M =
P–CH–P, JH–P = 9.9 Hz), 6.55 (m, br, 2 H, Ph), 6.93 (m, 4
¯
1
1666.48, triclinic, space group P1, a = 12.585(3), b = 16.613(3),
H) 7.09–7.58 (m, 23 H, Ph), 8.02 (m, 4 H, Ph) ppm. 13C{ H}
◦
˚
c = 21.407(4) A, a = 84.54(3), b = 82.55(3), g = 76.71(3) , V =
NMR (d8-THF, 75 MHz): d 3.3 (t, SiMe3), 19.8 (NamidePhMe),
3
-1
˚
1
4309.3(15) A , T = 200(2) K, Z = 2, m(Mo-Ka) = 0.854 mm ,
20.3 (NimiePhMe), 44.2 (t, P–C–P, JC–P = 66.9 Hz), 121.6 (Ph),
42069 reflections measured, 22790 independent reflections (Rint
=
124.2 (Ph), 125.4 (Ph), 126.4 (Ph), 127.8–128.7 (m, Ph), 132.2–
0.0636). The final R1 values were 0.0589 (I > 2s(I)). The final
wR(F2) values were 0.1075 (all data).
=
133.5 (m, Ph), 141.2 (Ph), 147.3 (Ph), 158.2 (N C–N) ppm.
1
31P{ H} NMR (d8-THF, 121 MHz): d 24.8 ppm. EI-MS (70 eV):
m/z (%) = 922 ([M]+, 2), 876 ([M - 3Me]+, 2), 843 ([M -
Ph]+, 3), 698 ([M - DTC]+, 54), 621 ([M - DTC - Ph]+, 91),
558 ([CH2(PPh2NSiMe3)2]+, 75), 543 ([CH2(PPh2NSiMe3)2-Me]+,
95), 455 ([CH2(PPh2)(PPh2NSiMe2)]+, 66), 222 ([DTC]+, 93).
C52H58N4P2Si2Zn (922.57): calc. C 67.70, H 6.34, N 6.07; found: C
68.08, H 6.17 N 5.96%.
Crystal data for 2. C31H40I2N2P2Si2Zn·2(C4H8O),
M
=
1022.15, monoclinic, space group P21/n, a = 11.523(2), b =
◦
3
˚
˚
22.951(5), c = 16.995(3) A, b = 91.95(3) , V = 4491.9(16) A ,
T = 203(2) K, Z = 4, m(Mo-Ka) = 2.079 mm-1, 8149 reflections
measured, 8149 independent reflections. The final R1 values were
0.0462 (I > 2s(I)). The final wR(F2) values were 0.1135 (all data).
The goodness of fit on F2 was 0.899.
=
[{(Me3SiNPPh2)2CH(Ph2C C–O)}ZnPh] (5). A solution of
[{(Me3SiNPPh2)2CH}ZnPh] (200 mg, 0.28 mmol) in 5 ml of
= =
toluene was added to a stirred solution of Ph2C C O (39 mg,
Crystal data for 3. C37H44N2P2Si2Zn, M = 700.23, monoclinic,
˚
0.2 mmol) in 1 ml of toluene at ambient temperature. The yellow
solution is stirred for 4 h. The reaction mixture was filtered and
the solvent removed in vacuum. Pale yellow single crystals suitable
for X-ray analysis could be obtained from hot THF. Yield: 120 mg
(46%).
space group P21/n, a = 10.286(2), b = 16.726(3), c = 22.270(5) A,
◦
3
˚
b = 101.73(3) , V = 3751.1(13) A , T = 203(2) K, Z = 4, m(Mo-
Ka) = 0.831 mm-1, 30061 reflections measured, 8939 independent
reflections (Rint = 0.0616). The final R1 values were 0.0333 (I >
2s(I)). The final wR(F2) values were 0.0918 (all data).
7234 | Dalton Trans., 2010, 39, 7230–7235
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The Royal Society of Chemistry 2010
©

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Crystal data for 4. C52H58N4P2Si2Zn, M = 922.55, monoclinic,
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space group P21/c, a = 11.032(2), b = 19.711(4), c = 22.993(5) A,
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˚
b = 101.71(3) , V = 4895.9(17) A , T = 200(2) K, Z = 4, m(Mo-
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Crystal data for 5. C51H54N2OP2Si2Zn·C4H8O, M = 966.56,
monoclinic, space group P21/c, a = 10.987(2), b = 21.913(4), c =
◦
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˚
˚
21.031(4) A, b = 98.72(3) , V = 5005(2) A , T = 203(2) K, Z =
4, m(Mo-Ka) = 0.645 mm-1, 49953 reflections measured, 10625
independent reflections (Rint = 0.1287). The final R1 values were
0.0600 (I > 2s(I)). The final wR(F2) values were 0.1661 (all data).
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Acknowledgements
This work was supported by the Landesstiftung Baden-
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Dalton Trans., 2010, 39, 7230–7235 | 7235
©