Reactions of the bis(iminophosphoranyl)methane ligand CH2(Ph2P=NSiMe3)2 with nickel(II) halides and the structural characterization of ligand fragmentation products

Article abstract of DOI:10.1016/S0020-1693(02)01385-3

While anhydrous nickel(II) chloride reacts with CH₂(Ph₂P=NSiMe₃)₂ to afford the pseudotetrahedral complex NiCl₂[CH₂(Ph₂P=NSiMe₃) ₂] (2), the analogous reaction with anhydrous nickel(II) iodide gives the structurally related complex NiI₂[CH₂(PPh₂=NSiMe₃)(PPh ₂=NH)] (3) in which one of the trimethylsilyl groups of 1 has been replaced by hydrogen. Another reaction in which the fragmentation of 1 occurs is that with the hydrate NiCl₂·6H₂O; in this case a square-planar nickel(II) complex of composition [Ni{Ph₂PCH₂PPh₂(=NH)}₂]Cl _1.25(NO₃)_0.75 (4) was identified as one of the products. The phosphonium salt [Ph₂P(NH₂)NPPh₂(CH₃)]I (5) is found to be a major product of the reaction between 3 and CO. The structures of 2-5 have been established by X-ray crystallography.

Full text of DOI:10.1016/S0020-1693(02)01385-3

Inorganica Chimica Acta 346 (2003) 181ꢀ186
/
www.elsevier.com/locate/ica
Reactions of the bis(iminophosphoranyl)methane ligand
NSiMe3)2 with nickel(II) halides and the structural
characterization of ligand fragmentation products
CH2(Ph2Pꢀ
/
Mani Ganesan, Phillip E. Fanwick, Richard A. Walton *
Department of Chemistry, Purdue University, 1393 Brown Building, West Lafayette, IN 47907-1393, USA
Received 13 August 2002; accepted 29 September 2002
Abstract
While anhydrous nickel(II) chloride reacts with CH2(Ph2Pꢀ
NSiMe3)2] (2), the analogous reaction with anhydrous nickel(II) iodide gives the structurally related complex NiI2[CH2(PPh2ꢀ
NSiMe3)(PPh2ꢀNH)] (3) in which one of the trimethylsilyl groups of 1 has been replaced by hydrogen. Another reaction in which
the fragmentation of 1 occurs is that with the hydrate NiCl2×6H2O; in this case a square-planar nickel(II) complex of composition
[Ni{Ph2PCH2PPh2(ꢀNH)}2]Cl1.25(NO3)0.75 (4) was identified as one of the products. The phosphonium salt [Ph2P(NH2)-
NPPh2(CH3)]I (5) is found to be a major product of the reaction between 3 and CO. The structures of 2ꢀ
/
NSiMe3)2 to afford the pseudotetrahedral complex NiCl2[CH2(Ph2Pꢀ
/
/
/
/
/
/5 have been established
by X-ray crystallography.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Crystal structures; Nickel complexes; Iminophosphoranyl complexes
1. Introduction
[1], transition metal [2] and lanthanide metal [3] centers
has yielded a diverse array of interesting complexes in
which these ligands exhibit a variety of intriguing
coordination modes. To date, the bulk of the transition
metal chemistry that has been developed involves the
Group 4 elements [2a,b] and various platinum metals
In recent years the coordination of bis(iminophos-
?
phoranyl)methane ligands CH2(R2Pꢀ
/
NSiMe3)2 (I) and
NSiMe3)2]ꢁ (II), as well as
?
their monoanions [CH(R2Pꢀ
/
[2eꢀ
/
j]. In the present report we describe the reactions of
NSiMe3)2 (1), bis[trimethylsilyli-
the ligand CH2(Ph2Pꢀ
/
minodi(phenyl)phosphoranyl]methane, with nickel(II)
halides which yield cases of products in which the ligand
1 remains intact or has undergone fragmentation. The
crystal structures of four products are reported.
2. Experimental
other ligands of a closely similar type,1 to main group
2.1. Starting materials and reaction procedures
* Corresponding author. Tel.: ꢂ
0239.
E-mail address: rawalton@purdue.edu (R.A. Walton).
/
1-765-494-5464; fax: ꢂ1-765-494-
/
The bis(iminophosphoranyl)methane CH2(Ph2Pꢀ
/
NSiMe3)2 (1) was prepared by the literature method
[4]. Samples of anhydrous NiI2 were purchased from
1
These include the dianionic form of these ligands as well as
derivatives where the bridgehead ꢀCH2 ꢀ group is changed to ꢀ
CH(R?)ꢀ
Strem Chemicals and the hydrate NiCl2×
/
6H2O from J.T.
/
/
/
/
.
Baker Chemical Co. Anhydrous NiCl2 was obtained by
0020-1693/03/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 0 - 1 6 9 3 ( 0 2 ) 0 1 3 8 5 - 3

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M. Ganesan et al. / Inorganica Chimica Acta 346 (2003) 181ꢀ186
/
dehydrating the hexahydrate with the use of thionyl
chloride. Organic solvents were purchased from com-
mercial sources and deoxygenated by purging with N2(g)
prior to use. Reactions were carried out under an
atmosphere of N2.
690(vs), 667(vw), 618(w), 555(w), 524(w), 491(m-s),
476(m-w), 422(vw).
2.4. Synthesis of [Ni{Ph2PCH2PPh2(ꢀ
/
NH)}2]Cl1.25-
(NO3)0.75 (4)
IR spectra were recorded as KBr pellets on a Perkinꢀ
/
Elmer 2000 FT-IR spectrometer. 1H and 31P{1H} NMR
spectra were obtained with the use of a Varian INOVA
300 spectrometer. Proton resonances were referenced
internally to the residual protons in the incompletely
deuteriated solvent. The 31P{1H} spectra were recorded
at 121.6 MHz, with 85% H3PO4 as an external standard.
Electronic absorption spectra were obtained with use of
a Cary 300 spectrophotometer. The magnetic moment
of 3 was determined at Texas A&M University with the
use of a SQUID magnetometer. Elemental microana-
lyses were performed by Dr. H.D. Lee of the Purdue
University Microanalytical Laboratory.
A mixture of NiCl2×
/
6H2O (0.10 g, 0.42 mmol) and
ligand 1 (0.50 g, 0.90 mmol) in 50 ml of dichloromethane
was stirred at room temperature (r.t.) for 4 days. The
light green reaction mixture was centrifuged, and the
clear solution concentrated to 10 ml and then carefully
layered with hexanes. A mixture of orangeꢀyellow
/
crystals of 4 and an unidentified pale green microcrystal-
line material formed. The crystals of 4 were separated by
hand, washed with a dichloromethane/hexane mixture
and dried under vacuum. Yield 0.026 g (6%). Anal.
Found: C, 58.53; H, 4.92; N, 4.50. Calc for
C51H48Cl3.25N2.75NiO2.25P4 (i.e. 4×
/CH2Cl2): C, 59.28;
H, 4.68; N, 3.73%. A single crystal X-ray structure
determination of the product prior to drying under a
2.2. Synthesis of NiCl2[CH2(PPh2ꢀ
/
NSiMe3)2] (2)
vacuum showed the orangeꢀ
composition 4×2CH2Cl2.
IR spectrum (KBr pellet, 1650ꢀ
/
yellow crystals to be of
A mixture of anhydrous NiCl2 (0.22 g, 1.70 mmol)
and ligand 1 (0.94 g, 1.68 mmol) in 50 ml of toluene was
refluxed for 3 days, the solvent evaporated, the residue
dissolved in 25 ml of dichloromethane and centrifuged
to remove any insoluble materials. The supernatent was
concentrated to ca. 15 ml and then carefully layered with
/
/
400 cmꢁ1): 1621(m),
1589(m-w), 1574(w), 1484(m), 1438(vs), 1373(s),
1337(vs,br), 1241(w), 1162(m-s), 1118(vs), 1100(s),
1073(w), 991(vs), 902(m-w), 829(w), 786(m-s), 745(vs),
734(s), 691(vs), 616(w), 566(w), 534(m-w), 508(s),
481(m), 453(w).
hexanes. Crystals of composition 2×
/
CH2Cl2 (as char-
acterized by X-ray crystallography) were isolated and
dried under a vacuum which led to partial loss of the
lattice dichloromethane solvent molecule. Yield 0.13 g
(11%). Anal. Found: C, 51.99; H, 5.64; N, 4.07. Calc for
2.5. Synthesis of [Ph2P(NH2)NPPh2(CH3)]I (5)
A stream of CO gas was passed through a solution of
3 (0.20 g, 0.25 mmol) in 25 ml of dichloromethane for 30
min. and the resulting solution kept under a CO
atmosphere for 4 days. During this time the solution
turned colorless. The reaction mixture was then centri-
fuged and the supernatent concentrated to 15 ml and
treated with hexane (10 ml). After 7 days a crop of
colorless crystals were filtered off and carefully dried.
Yield 0.065 g. Anal. Found: C, 55.53; H, 4.63; N, 5.08.
Calc. for C25H25IN2P2: C, 55.36; H, 4.65; N, 5.16%.
C
31.5H41Cl3N2NiP2Si2 (i.e. 2×
5.65; N, 3.83%.
IR spectrum (KBr pellet, 1600ꢀ
/
0.5CH2Cl2): C, 51.02; H,
/
400 cmꢁ1): 1591(w),
1488(w), 1439(m-s), 1353(m-w), 1262(s), 1249(s),
1186(m), 1123(vs), 1114(s), 1092(s), 1075(m-s),
1029(w), 999(w), 840(w), 804(vs), 764(m-s), 737(s),
719(s), 693(s), 621(w), 533(m-w), 513(m-w), 494(m-w),
469(m-w), 416(w).
2.3. Synthesis of NiI2[CH2(PPh2ꢀ
/
NSiMe3)(PPh2ꢀ
/
IR spectrum (KBr pellet, 1600ꢀ
400 cmꢁ1): 1589(m-
/
NH)] (3)
w), 1558(m-w), 1483(m-w), 1438(m-s), 1416(w),
1318(vs), 1291(s), 1274(s), 1183(m), 1162(w), 1121(s),
1073(vw), 1029(vw), 998(m-w), 943(m-s), 896(m-s),
801(m), 757(m-s), 746(s), 721(m-s), 692(vs), 644(w),
616(vw), 520(s), 488(m), 470(m-s), 449(w), 438(w).
A mixture of anhydrous NiI2 (0.25 g, 0.80 mmol) and
ligand 1 (0.90 g, 1.61 mmol) was refluxed for 4 days in
50 ml of toluene to give an insoluble green solid that was
filtered off, washed with diethyl ether and dried under a
vacuum. Yield: 0.55 g (86%). The product was recrys-
tallized from dichloromethane/hexanes. Anal. Found: C,
41.36; H, 3.74; N, 3.58. Calc for C28H31I2N2NiP2Si: C,
42.10; H, 3.88; N, 3.50%.
31P{1H} NMR (CDCl3, d): ꢂ
/
20.9 (d, 2J(PP)ꢃ
/
3 Hz),
2
1
ꢂ
/
21.7(d, J(PP)ꢃ
/
3 Hz). H NMR (CDCl3, d): ꢂ
/
2.54
2
4
(dd, CH3, J(PH)ꢃ
/
12.9 Hz, J(PH)ꢃ
/
1.2 Hz), ꢂ
/4.82
(s, br, NH2), ꢂ7.3 to ꢂ
/
/
7.9 (m, Ph).
IR spectrum (KBr pellet, 1600ꢀ
/
400 cmꢁ1): 1589 (m-
2.6. X-ray crystallography
w), 1545(w), 1484(m-w), 1438(s), 1352(w), 1335(vw),
1312(w), 1251(m-s), 1177(m), 1115(vs), 1085(s), 1042(m-
w), 1021(m-w), 997(m), 886(vw), 841(s), 790(s), 741(vs),
Single crystals of compounds 2ꢀ
described in Sections 2.2, 2.3, 2.4 and 2.5. Data
/
5 were obtained as

M. Ganesan et al. / Inorganica Chimica Acta 346 (2003) 181ꢀ
/186
183
collections were performed at 150 (9
monochromated Mo Ka radiation (lꢃ
/
1) K with graphite-
˚
0.71073 A) on a
able model involved three different anion positions for
[Cl]ꢁ and/or [NO3]ꢁ within the asymmetric unit, such
that there is one [Cl]ꢁ at full occupancy, one [Cl]ꢁ
position at 20% occupancy, and one position which was
modeled as a disorder between [NO3]ꢁ and [Clꢁ] with
75 and 5% occupancies, respectively. This model gives
an appropriate charge balance for the nickel(II) dica-
tion. There are also two independent, well-behaved
CH2Cl2 molecules in the asymmetric unit. All non-
hydrogen atoms of 4 were refined with anisotropic
thermal parameters. The structure solution and refine-
ment of 5, with all non-hydrogen atoms anisotropic,
proceeded routinely.
/
Nonius Kappa CCD diffractometer. Lorentz and polar-
ization corrections were applied to the data sets. The key
crystallographic data are given in Table 1.
The structures of 2 and 5 were solved by direct
methods using SIR97[5], the structure of 3 was solved
with use of SHELXS-97 [6], and that of 4 with the
structure solution program PATTY in DIRDIF-99 [7]. The
remaining atoms were located in succeeding difference
Fourier syntheses. Hydrogen atoms were placed in
calculated positions according to idealized geometries
˚
0.95 A and U(H)ꢃ1.3Ueq(C). They were
with Cꢀ
/
Hꢃ
/
/
included in the refinement but constrained to ride on the
atom to which they are bonded. An empirical absorp-
tion correction using SCALEPACK [8] was applied. The
final refinements were performed by the use of the
program SHELXL-97 [9]. The highest peak in the final
3. Results and discussion
The reaction of anhydrous NiCl2 with bis[trimethylsi-
lyliminodi(phenyl)phosphoranyl]methane (1) in reflux-
ing toluene for periods of up to 3ꢀ
difference Fouriers of 2ꢀ5 had a height of 0.59, 3.21,
/
0.63 and 0.47 e Aꢁ3, respectively.
˚
/4 days affords
The structure solution and refinement for 2 proceeded
routinely. The atoms Ni, Cl(1), Cl(2) and C(1b) of the
nickel complex are located on a crystallographic plane
of symmetry. The lattice molecule of dichloromethane
solvent, which is also located on a special position, was
modeled satisfactorily with minimal disorder and aniso-
tropic thermal parameters for its C and Cl atoms. For
complex 3, in which the ligand 1 has lost a trimethylsilyl
group, the hydrogen atom bound to N(2) was not
located but its presence can be inferred from the other
properties of this normal paramagnetic, tetrahedral
Ni(II) complex. All non-hydrogen atoms were refined
anisotropically. The only problem encountered in the
structure solution of 4 concerned the nature of the
counter anions. A satisfactory and chemically reason-
crystalline NiCl2[CH2(PPh2ꢀNSiMe3)2] (2). This tetra-
/
hedral nickel(II) complex was characterized by X-ray
crystallography. An ORTEP [10] representation of this
conventional structure is shown in Fig. 1. A similar
reaction between anhydrous NiI2 and 1 also gave a
tetrahedral nickel(II) complex, but in this case one of the
trimethylsilyl groups of the ligand had been replaced by
hydrogen to give NiI2[CH2(PPh2ꢀ
/
NSiMe3)(PPh2ꢀ
/
NH)]
(3) in high yield. The structure of 3 (Fig. 2) is otherwise
similar to that of 2 with the exception of differences
engendered by changes in the size of the halide ligands
and the unsymmetrical nature of the chelating ligand in
3. The Nꢀ
Figs. 1 and 2) are in the ranges 103.8ꢀ
and 101.7ꢀ112.78 (XꢃI). When compared to the
/
Niꢀ
/
X angles (not listed in the captions to
/
115.58 (XꢃCl)
/
/
/
Table 1
Crystallographic data for NiCl2[CH2(PPh2ꢀ
/
NSiMe3)2]×
/
CH2Cl2 (2), NiI2[CH2(PPh2ꢀ
/
NSiMe3)(PPh2ꢀ
/
NH)] (3), [Ni{Ph2PCH2PPh2-
(ꢀNH)}2]Cl1.25(NO3)0.75 2CH2Cl2 (4) and [Ph2P(NH2)NPPh2(CH3)]I (5)
/
×
/
Compound
2
3
4
C52H50Cl5.25N2.75NiO2.25P4
5
Empirical formula
Formula weight
Space group
C32H42Cl4N2NiP2Si2
773.35
C28H31I2N2NiP2Si
798.12
C25H25IN2P2
542.34
1118.23
P21/n (no. 14)
16.3023(2)
12.2896(2)
27.2235(7)
90
P21/m (no. 11)
9.1894(3)
20.1040(7)
10.6672(4)
90
P21/n (no. 14)
10.5919(4)
14.8366(6)
19.5188(6)
90
P1 (no. 2)
8.88560(10)
12.0669(2)
13.3459(3)
106.6690(10)
98.0920(10)
111.3460(10)
1227.65(9)
2
˚
a (A)
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
V (A )
Z
rcalc (g cmꢁ3
103.9260(10)
90
89.978(3)
90
103.3459(7)
90
3
˚
1912.8(2)
2
1.343
3067.3(3)
4
1.728
5306.9(3)
4
1.399
)
1.467
1.431
m(Mo Ka) (mmꢁ1
R (Fo)
)
0.959
0.041
2.788
0.067
0.793
0.042
a
0.028
0.070
1.094
2
b
Rw (Fo
GOF
)
0.102
1.030
0.171
1.003
0.108
1.037
a
Rꢃ
Rwꢃ
/
ajFojꢁ
/
jFcj/ajFoj with Fo2ꢀ
/
2s(Fo2).
b
2
2
2 2 1/2
/
[a w(jFo jꢁ
/
jFc j)2/a wjFo j ]
.

184
M. Ganesan et al. / Inorganica Chimica Acta 346 (2003) 181ꢀ186
/
Fig. 3. ORTEP [10] representation of the structure of the
NH)}2]2ꢂ cation as present in the crystals of 4×
2CH2Cl2. The thermal ellipsoids are drawn at the 50% probability level
Fig. 1. ORTEP [10] representation of the structure of the nickel(II)
[Ni{Ph2PCH2PPh2(ꢀ
/
/
complex NiCl2[CH2(PPh2ꢀ
/
NSiMe3)2] as present in crystals of 2×
/
CH2Cl2. Thermal ellipsoids are drawn at the 50% probability level
except for the carbon atoms of the phenyl rings which are circles of
except for the carbon atoms of the phenyl groups which are circles of
˚
arbitrary radius. Selected bond distances (A) and bond angles (8) are as
arbitrary radius. This molecule contains a plane of symmetry
comprising atoms Ni, Cl(1), Cl(2) and C(1b). Selected bond distances
follows: Niꢀ
P(3) 2.1646(7), N(2)ꢀ
N(4) 89.99(10), P(1)ꢀ
N(2)ꢀNiꢀP(3) 170.20(8), N(4)ꢀ
85.75(7), NiꢀN(2)ꢀP(2) 126.91(15), Niꢀ
/
N(2) 1.907(2), Niꢀ
P(2) 1.600(2), N(4)ꢀ
NiꢀP(3) 98.91(3), N(2)ꢀ
NiꢀP(1) 170.47(8), N(4)ꢀ
N(4)ꢀP(4) 126.81(14).
/
N(4) 1.905(2), Niꢀ
P(4) 1.598(2); N(2)ꢀ
NiꢀP(1) 86.62(8),
NiꢀP(3)
/
P(1) 2.1636(7), Niꢀ
/
/
/
/
Niꢀ
/
˚
(A) and bond angles (8) are as follows: Niꢀ
2.2747(9), NiꢀN 2.0182(19), NꢀP 1.5910(19), Nꢀ
NiꢀCl(2) 111.87(4), NꢀNiꢀN? 104.97(11), NiꢀNꢀ
PꢀC(1b) 110.42(12), PꢀC(1b)ꢀP? 118.71(18).
/
Cl(1) 2.2664(10), Niꢀ
Si 1.757(2); Cl(1)ꢀ
P 119.13(11), Nꢀ
/
Cl(2)
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
monodentate ligands of the types Me3SiNꢀ
HNꢀPR3 [11], the PꢀN distances in 2 and 3 (range
1.591ꢀ1.603 A) are quite normal. These results, which
/
PR3 and
/
/
˚
/
accord with data reported for bis(iminophosphora-
nyl)methane ligands bound to main group [1a] and
heavier transition metals [2g,j], also show that these Pꢀ
/
N distances are significantly longer than those asso-
ciated with uncoordinated ligands [1a,2a,g,12]. Further-
more, there is no indication that the chelating ligand in 3
is monoanionic and deprotonated [CH2(PPh2ꢀ
NSiMe3)(PPh2ꢀ
N)]ꢁ which would make it a complex
of nickel(III); differences between the pairs of NiꢀN and
PꢀN distances in 3 are at most small and attributable to
the replacement of Me3Si by H.
The electronic absorption spectra of 2 and 3 in
dichloromethane (800ꢀ400 nm) are consistent with their
formulation as pseudotetrahedral nickel(II) species;
each shows the characteristic 3T1(P)03T1 transition
(n3) [13], which for 2 is at 15,300 cmꢁ1 (e ꢁ
150) with a
broad shoulder at 17,480 cmꢁ1, and for 3 at 14,265
cmꢁ1 (e ꢁ 16,400 cmꢁ1. The
450) with a shoulder at ꢁ
/
/
/
/
/
/
Fig. 2. ORTEP [10] representation of the structure of the nickel(II)
NH)] (3). Thermal ellipsoids
are drawn at the 50% probability level except for the carbon atoms of
/
complex NiI2[CH2(PPh2ꢀ
/
NSiMe3)(PPh2ꢀ
/
the phenyl rings which are circles of arbitrary radius. Selected bond
˚
distances (A) and bond angles (8) are as follows: NiꢀI(1) 2.6058(16),
/
/
/
magnetic moment of 3 is 3.26 mB at 300 K which is in
further accord with its pseudotetrahedral nickel(II)
structure [14,15].
Niꢀ
1.596(10), N(2)ꢀ
125.87(5), N(1)ꢀ
N(2)ꢀP(2) 128.1(5), N(1)ꢀ
107.1(5), P(1)ꢀC(1b)ꢀP(2) 118.9(5).
/
I(2) 2.6112(16), Niꢀ
P(2) 1.603(9), N(1)ꢀ
NiꢀN(2) 107.1(4), Niꢀ
P(1)ꢀC(1b) 112.2(5), N(2)ꢀ
/
N(1) 1.998(10), Niꢀ
Si(1) 1.816(11); I(1)ꢀ
N(1)ꢀP(1) 122.2(6), Niꢀ
P(2)ꢀC(1b)
/
N(2) 1.950(9), N(1)ꢀ
/
P(1)
/
/
/Niꢀ
/
I(2)
/
/
/
/
/
/
/
/
/
/
When the hexahydrate NiCl2×
/
6H2O was used in place
/
/
of anhydrous NiCl2, and the reaction with ligand 1 was
carried out in dichloromethane at room temperature for
4 days, a mixture of products was formed, one of which
structural data available for phosphoraneimine com-
plexes of halides of the first transition series that contain
was obtained as orangeꢀyellow crystals (4) from a
/

M. Ganesan et al. / Inorganica Chimica Acta 346 (2003) 181ꢀ
/186
185
Fig. 4. ORTEP [10] representation of the structure of the [Ph2P(NH2)NPPh2(CH3)]ꢂ cation as present in the crystals of its iodide salt 5. Thermal
˚
ellipsoids are drawn at the 50% probability level except for the hydrogen atoms associated with C(2) and N(1). Selected bond distances (A) and bond
angles (8) are as follows: N(1)ꢀ
/
P(1) 1.633(2), P(1)ꢀ
/
N(1b) 1.5761(18), N(1b)ꢀ
/
P(2) 1.5722(18), P(2)ꢀ
/
C(2) 1.792(2); N(1)ꢀ
/
P(1)ꢀN(1b) 121.36(10),
/
P(1)ꢀN(1b)ꢀP(2) 142.91(13), N(1b)ꢀ
/
/
/
P(2)ꢀC(2) 114.79(10).
/
dichloromethane/hexane mixture. This product was
identified as being of composition [Ni{Ph2PCH2PPh2-
plexes that contain these fragments have been structu-
rally characterized. In addition, the full structural
characterization of the phosphonium salt 5 confirms
the identity of this previously reported cation [12,16].
(ꢀ
/
NH)}2]Cl1.25(NO3)0.75
×
/
2CH2Cl2 (4×/2CH2Cl2) and its
structure established by a single crystal X-ray structure
determination. The presence of [NO3]ꢁ in 4 was
confirmed by IR spectroscopy (KBr pellet) which
showed a strong band at 1337 cmꢁ1 assigned to the n3
mode of this anion. An ORTEP [10] representation of the
square planar nickel(II) cation is shown in Fig. 3 and
demonstrates that like 3 it is obtained by fragmentation
of ligand 1 but in this instance the bidentate ligand
contains a mixed phosphane/phosphoraneimine donor
set. The low yield has prevented us from carrying out
more extensive investigations of 4. The structural
parameters for the phosphoraneimine portion of this
ligand resemble those found for complex 2 (Fig. 2).
A third ligand fragmentation/rearrangement product
obtained during the course of this study was isolated in
quite high yield during attempts to carbonylate the
nickel(II) iodide complex 3. Quite unexpectedly we
obtained the salt [Ph2P(NH2)NPPh2(CH3)]I (5), ami-
no[methyldiphenylphosphoranylidenamido]diphenyl-
phosphonium iodide; this is a known compound [16], as
is its chloride salt [12]. The spectroscopic data for 5 are
given in Section 2.5; NMR spectral data for the chloride
salt have previously been measured in methanol [16].
The ORTEP [10] representation of the structure of the
cation is shown in Fig. 4 and confirms the identity of
this compound. The mechanism of the reaction that
produces 5 through the decomposition of 3 has yet to be
established, although the chloride salt is known to be
formed by the reaction of the ligand 1 with HCl which
leads to the loss of the trimethylsilyl groups as Me3SiCl
[12].
4. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC Nos. 192891ꢀ
/
192894 for com-
pounds 2ꢀ5, respectively. Copies of this information
/
may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK
(fax: ꢂ44-1223-336-033; e-mail: deposit@ccdc.cam.ac.
/
uk or www: http://www.ccdc.cam.ac.uk).
Acknowledgements
We thank the John A. Leighty Endowment Fund for
support of this work. We are also grateful to Dr. S.K.
Chattopadhyay for some experimental assistance.
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