Neutral and anionic antimony(III) species supported by a bicyclic guanidinate

Article abstract of DOI:10.1002/ejic.201101189

Bicyclic guanidine 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine (hppH) was investigated as a source of anionic or neutral ligand at antimony. Reaction of the in situ generated lithium guanidinate with SbCl₃ in a 1:1 or 2:1 ratio forms the expected metathesis products Sb(hpp) _nCl_3-n (1, n = 1; 2, n = 2). The molecular structures of 1 and 2 were determined by X-ray diffraction, which shows chelating guanidinates and suggests the presence of a stereochemically active lone pair of electrons. The reaction of two equivalents of the neutral guanidine hppH with SbCl ₃ proceeds via proton transfer between the hpp fragments, affording the ion pair [hppH₂][Sb(hpp)Cl₃] (3), where [Sb(hpp)Cl₃]^- is an unusual example of a monometallic antimonate(III) anion. The molecular structure of 3 shows hydrogen bonding between two of the chlorides and the NH functionalities of the guanidinium cation. Bicyclic guanidinate [hpp]^- (hppH = 1,3,4,6,7,8-hexahydro-2H- pyrimido[1,2-a]pyrimidine) chelates to antimony in Sb(hpp)Cl₂ and Sb(hpp)₂Cl. Attempted preparation of the neutral adduct with hppH afforded the salt [hppH₂][Sb(hpp)Cl₃], in which a net proton transfer between guanidine molecules had taken place. Copyright

Full text of DOI:10.1002/ejic.201101189

FULL PAPER
DOI: 10.1002/ejic.201101189
Neutral and Anionic Antimony(III) Species Supported by a Bicyclic
Guanidinate
Benjamin M. Day,[a] Martyn P. Coles,*[b] and Peter B. Hitchcock[a]
Keywords: N ligands / Main group elements / Group 15 elements / Antimony / Stereochemically active lone pairs
Bicyclic guanidine 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-
a]pyrimidine (hppH) was investigated as a source of anionic
or neutral ligand at antimony. Reaction of the in situ gener-
ated lithium guanidinate with SbCl3 in a 1:1 or 2:1 ratio forms
the expected metathesis products Sb(hpp)nCl3–n (1, n = 1; 2,
n = 2). The molecular structures of 1 and 2 were determined
by X-ray diffraction, which shows chelating guanidinates
and suggests the presence of a stereochemically active lone
pair of electrons. The reaction of two equivalents of the neu-
tral guanidine hppH with SbCl3 proceeds via proton transfer
between the hpp fragments, affording the ion pair
[hppH2][Sb(hpp)Cl3] (3), where [Sb(hpp)Cl3]– is an unusual
example of a monometallic antimonate(III) anion. The mo-
lecular structure of 3 shows hydrogen bonding between two
of the chlorides and the NH functionalities of the guanid-
inium cation.
metals. The propensity for bridging has been explained in
terms of a wide (parallel) projection of the nitrogen donor
orbitals in [hpp]–. This contrasts with the situation in acy-
clic anions in which steric interactions between the nitrogen
substituents force these orbitals to point towards the
“mouth” of the ligand (Figure 2).
Introduction
We have a long-standing interest in the application of
bicyclic guanidines as neutral[1] and anionic[2] ligands at
main group and transition metal centres. Much of our work
has focussed on the {6:6}-fused system, hppH (1,3,4,6,7,8-
hexahydro-2H-pyrimido[1,2-a]pyrimidine), during which
time we have noted a diverse range of coordination modes
(Figure 1). In addition to the bidentate coordination A, typ-
ical for acyclic guanidinate derivatives,[3] constraining the
nitrogen substituents of the amidine component into the
six-membered heterocycles promotes a number of bridging
modes B–G incorporating two,[4] three[4h,4i,5] or four[4h,4i,6]
Figure 2. Schematic representation of the orbital projection in
[hpp]– and a generic acyclic guanidinate anion, [R2NC{NRЈ}2]–.
Within groups 13 and 14, the chemistry of the [hpp]–
anion has focussed mainly on the lighter elements boron[7]
and silicon.[8] The corresponding coordination chemistry of
aluminium,[4a] gallium[4k] and tin[4d] has shown a tendency
for the ligand to adopt a bridging B-type coordination (Fig-
ure 1), although both A and B coordination have been
noted for SnII.[4d] We were curious to see whether coordi-
nating the [hpp]– anion to a larger metal ion would favour
chelation (A-type bonding) and targeted antimony(III)
compounds to determine whether this would be the case
[effective ionic radii: Al3+ 0.535 Å, Ga3+ 0.62 Å, Sb3+
0.76 Å].[9]
Earlier publications describing amidinate complexes of
antimony in the +3[10] and +5 oxidation states[11] were
mainly restricted to structural reports. More recently atten-
tion has focussed on the coordination chemistry of anti-
mony(III) (Figure 3),[12] with interest primarily derived
from the ability of such ligands to support low-oxidation-
state metals.[12b] We report herein our preliminary studies
Figure 1. Reported bonding modes for the bicyclic guanidinate de-
rived from 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine
(hppH).
[a] Department of Chemistry, University of Sussex,
Falmer, Brighton BN1 9QJ, UK
[b] School of Chemical and Physical Sciences, Victoria University
of Wellington,
P. O. Box 600, Wellington, New Zealand
Fax: +64-4-4635237
E-mail: martyn.coles@vuw.ac.nz
Eur. J. Inorg. Chem. 2012, 841–846
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
841

B. M. Day, M. P. Coles, P. B. Hitchcock
FULL PAPER
into the application of [hpp]– as a ligand at SbIII, including
the crystal structure of an unanticipated ionic species con-
sisting of a guanidinium cation and an antimonate(III)
anion.
Scheme 1. Synthesis of Sb(hpp)nCl3–n (1, n = 1; 2 n = 2) and
[hppH2][Sb(hpp)Cl3] (3).
spectra are consistent with a symmetrical environment for
the guanidinate ligand in each compound.
The X-ray crystal structure of compound 1 (Tables 1 and
2) confirmed the formulation as the monomeric dichloride
Sb(hpp)Cl2 (Figure 4a). The geometry at the metal may be
described as highly distorted trigonal bipyramidal, the axial
positions defined by Cl1 and N2 and a stereochemically
Figure 3. Examples of structurally characterized SbIII–amidinate
and –guanidinate compounds (Ar = 2,6-iPr2C6H3).
Table 2. Selected bond lengths [Å] and angles [°] for 1.
Results and Discussion
Sb–N1
Sb–Cl1
C1–N1
C1–N3
N1–Sb–N2
N1–Sb–Cl2
N2–Sb–Cl2
2.060(6)
2.587(2)
1.332(9)
1.345(10)
61.3(2)
96.3(2)
89.77(19)
Sb–N2
Sb–Cl2
C1–N2
2.244(7)
2.414(2)
1.341(9)
The 1:1 reaction of in situ generated Li[hpp][4h] with one
equivalent of SbCl3 gave colourless crystals of Sb(hpp)Cl2
(1) upon work-up (Scheme 1). The analogous procedure
with 0.5 equiv. of anitimony(III) chloride afforded the
bis(guanidinate) complex Sb(hpp)2Cl (2). Three resonances
N1–Sb–Cl1
N2–Sb–Cl1
Cl1–Sb–Cl2
85.79(17)
146.90(16)
90.57(7)
1
for the annular methylene groups in the H and 13C NMR
Table 1. Crystal structure and refinement data for Sb(hpp)Cl2 (1), Sb(hpp)2Cl (2) and [hppH2][Sb(hpp)Cl3] (3).
1
2
3
Empirical formula
Mr
C7H12Cl2N3Sb
330.85
C14H24ClN6Sb
433.59
C14H26Cl3N6Sb
506.51
T [K]
173(2)
0.10ϫ0.05ϫ0.01
monoclinic
P21/n (alternative No.14)
9.3783(8)
8.1401(8)
13.8748(10)
90
99.636(5)
90
1044.26(16)
4
2.10
3.11
173(2)
173(2)
Crystal size [mm]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
0.24ϫ0.14ϫ0.08
monoclinic
P21/c (No. 14)
12.0687(5)
8.3115(3)
16.9864(8)
90
100.511(2)
90
1675.30(12)
4
0.15ϫ0.10ϫ0.10
triclinic
¯
P1 (No. 2)
7.8127(2)
8.5487(2)
14.8964(4)
100.132(2)
91.754(1)
97.835(2)
968.73(4)
2
γ [°]
V [Å3]
Z
dcalcd. [Mgm–3]
Absorption coefficient [mm–1]
θ range [°]
1.72
1.81
1.74
1.85
3.50 to 26.02
8878
2049 [Rint = 0.101]
1617
1.72 to 27.48
10016
3797 [Rint = 0.049]
3176
3797/0/199
R1 = 0.030, wR2 = 0.083
R1 = 0.044, wR2 = 0.112
1.195
3.49 to 25.99
13137
3797 [Rint = 0.030]
3513
Reflections collected
Independent reflections
Reflections with IϾ2σ(I)
Data/restraints/parameters
Final R indices [IϾ2σ(I)]
Final R indices (all data)
GooF on F2
2049/0/118
3797/0/225
R1 = 0.060, wR2 = 0.146
R1 = 0.077, wR2 = 0.158
1.098
R1 = 0.021, wR2 = 0.047
R1 = 0.024, wR2 = 0.048
1.090
Largest diff. peak/hole [eÅ–3]
2.43 and –1.72[a]
1.34 and –1.84
0.40 and –0.46
[a] Near Sb.
842
www.eurjic.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 841–846

Antimony(III) Species Supported by a Bicyclic Guanidinate
active lone pair of electrons occupying an equatorial posi- are identical (within experimental uncertainty), suggesting
tion (Figure 5a). The Sb–N and Sb–Cl distances support efficient delocalization.
this with shorter bonds to the proposed equatorial atoms
The degree of aggregation of antimony compounds in-
and longer bonds to the corresponding axial atoms [Sb– corporating amidinate and guanidinate anions varies con-
N1(eq) 2.060(6) Å vs. Sb–N2(ax) 2.244(7) Å; Sb–Cl2(eq) siderably with the steric profile of the ligand and the solvent
2.414(2) Å vs. Sb–Cl1(ax) 2.587(2) Å]. The repulsive influ- from which the compound is crystallized (i.e., whether solv-
ence of the lone pair and acute bite angle of the guanidinate ate molecules are included in the crystal lattice). For exam-
[N1–Sb–N2 61.3(2)°] cause a large reduction of the N2–Sb– ple, the bulky amidinate and guanidinate compounds
Cl1 angle from its ideal linear arrangement to 146.90(16)°. Sb(RC{NRЈ}2)Cl2 (RЈ = Ar; R = tBu,[12c] Cy2N[12b]), the
Within the CN3 core of the guanidinate, the C–N distances former of which crystallizes as the bis(chloroform) solvate,
are monomeric in the solid state. In contrast, when R = tBu
and RЈ = iPr or Cy,[12c] or R = Ph and RЈ = SiMe3,[10a]
the molecules are linked by a single intermolecular Sb···Cl
contact to generate corner-bridged polymeric structures.
Compound 1 has two symmetry-related Sb···Cl contacts
[Sb···Cl 3.240 Å] that generate an edge-shared dimer (Fig-
ure 4b), as noted in Sb(nBuC{NiPr}2)Cl2.[12c] These inter-
molecular contacts may contribute to the elongation in the
Sb–Cl1 bond length described above.
The crystal structure of 2 (Figure 6, Tables 1 and 3)
shows a monomeric, five-coordinate antimony centre with
chelating [hpp]– ligands and a terminal chloride ligand. The
angles at the metal range from the small bite of the guanidi-
nates [57.32(10)° and 60.47(11)° for C1 and C8 ligands,
respectively] to 141.64(8)° for Cl–Sb–N5. The latter value is
close to that proposed for the trans-equatorial substituents
distorted by lone-pair repulsions and chelation in 1. A sim-
ilar metal geometry was observed for the bis(amidinate)
compound Sb(PhC{NSiMe3}2)2Cl,[10b] in which the metal
Figure 4. (a) Thermal ellipsoid plot (30% probability) of 1; (b)
schematic diagram showing the association of 1 into edge-shared
dimers.
Figure 6. Thermal ellipsoid plot (30% probability) for 2.
Table 3. Selected bond lengths [Å] and angles [°] for 2.
Sb–N1
Sb–N4
Sb–Cl
C1–N2
C8–N4
C8–N6
N1–Sb–N2
N1–Sb–N5
N2–Sb–N4
N2–Sb–Cl
N4–Sb–Cl
2.057(3)
2.151(3)
2.6831(9)
1.322(5)
1.340(4)
1.345(4)
57.32(10)
91.01(11)
131.44(11)
126.39(7)
82.20(8)
Sb–N2
Sb–N5
C1–N1
C1–N3
C8–N5
2.526(3)
2.209(3)
1.353(5)
1.355(5)
1.328(4)
N1–Sb–N4
N1–Sb–Cl
N2–Sb–N5
N4–Sb–N5
N5–Sb–Cl
95.33(11)
83.38(9)
79.17(10)
60.47(11)
141.61(8)
Figure 5. Top: geometries at antimony for (a) compound 1 and (b,
c) alternatives for compound 2. Bottom: localized and delocaliza-
tion descriptions of bonding in the Sb(hpp) fragment.
Eur. J. Inorg. Chem. 2012, 841–846
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
843

B. M. Day, M. P. Coles, P. B. Hitchcock
FULL PAPER
was described as having distorted octahedral geometry with ford the cation [hppH2]+ and the anion [hpp]–, the latter
a “stereochemically strongly effective lone electron pair”; of which coordinates to SbCl3. Mechanistic details of this
this description may be applied to the geometry of 2 (2-Oh, reaction are not known.
Figure 5b).
An alternative description for the geometry of 2 is a dis-
torted trigonal bipyramidal geometry (2-tbp, Figure 5c) in
which N2 is only loosely coordinated to the antimony cen-
tre. Evidence for this comes from a very long Sb–N2 bond
[2.526(3) Å] compared to the remaining Sb–N distances in
2 [2.057(3)–2.209(3) Å] and those in 1. We also note local-
ization of π-electron density in the N1–C1–N2 component
of the [hpp]– ligand, indicated by long C1–N1 and short
C1–N2 bonds [1.353(5) and 1.322(5) Å, respectively]. This
is consistent with a large contribution from localized bond-
ing of the I/IЈ type previously noted for amidinates in five-
coordinate aluminium systems.[13] The π-bonding in the
other guanidinate ligand shows a similar, although less pro-
nounced, trend.
Figure 8. Thermal ellipsoid plot (30% probability) of 3.
Table 4. Selected bond lengths [Å] and angles [°] for 3.
In addition to using the [hpp]– anion as a ligand in coor-
dination chemistry, the neutral guanidine, hppH, also serves
as an effective N-donor ligand.[4h,5a,14] The typical bonding
mode is by lone-pair donation from the imine nitrogen to
an available orbital on the metal centre. For metal halide
compounds, this interaction may be strengthened by intra-
molecular hydrogen bonding to the halide atom (Figure 7).
Many bis(N-donor ligand) adducts of antimony(III) chlor-
ide are known, including, for example, those of 1,4-diaza-
butadiene,[15] bipy,[16] 1,2-bis(aryl-imino)acenaphthene,[17]
4-phenylpyridine[18] and 2,6-dimethylaniline.[19] We there-
fore investigated the use of hppH as a neutral N-donor li-
gand with antimony(III) chloride as the metal reagent.
Sb–N1
2.2602(17)
2.5932(6)
2.5906(6)
1.357(3)
1.337(3)
1.331(3)
61.00(6)
96.72(5)
93.50(5)
84.82(5)
85.108(19)
Sb–N2
Sb–Cl2
C1–N1
C1–N3
C8–N5
2.0756(17)
2.6570(6)
1.320(3)
1.337(3)
1.338(3)
Sb–Cl1
Sb–Cl3
C1–N2
C8–N4
C8–N6
N1–Sb–N2
N1–Sb–Cl2
N2–Sb–Cl1
N2–Sb–Cl3
Cl1–Sb–Cl3
N1–Sb–Cl1
N1–Sb–Cl3
N2–Sb–Cl2
Cl1–Sb–Cl2
Cl2–Sb–Cl3
87.00(5)
144.33(5)
84.51(5)
174.225(19)
89.31(2)
The [Sb(hpp)Cl3]– anion is an unusual example of a mo-
nometallic antimonate(III) anion. The propensity for hal-
ides to bridge in anionic antimonate systems has strong
grounding in the literature. Although [SbCl4]– was structur-
ally described as early as 1970,[21] close contacts (less than
4.0 Å, the sum of the van der Waals radii) to additional
chloride ions are frequently encountered in the solid state.
The most common description of this unit is an octahe-
drally coordinated antimony within a polymeric chain
bridged by chloride ions.[22] Both the bromide and the
Figure 7. Coordination of a neutral hppH guanidine at a generic
metal halide fragment showing stabilization by intramolecular hy-
drogen bonding.
The reaction between two equivalents of hppH and iodide systems are known as isolated octahalodianti-
SbCl3 afforded colourless crystals of 3 after the appropriate monate(III) ions, [X3Sb(μ-X)2SbX3]2– (X = Br,[23] I[24]).
work-up (Scheme 1). The crystals were insoluble in com- Substitution by phenyl groups in the anions form the
mon NMR spectroscopic solvents but dissolved in [D3]- [Cl2(Ph)Sb(μ-Cl)2Sb(Ph)Cl2]2– dimer for the monophenyl
acetonitrile, enabling spectroscopic analysis. Key features anion, and the monomer is only formed for the diphenyl
include a broad resonance at 7.57 ppm with a relative inte- derivative [SbCl2Ph2]–.[25] This system is further compli-
1
gral of 2H in the H NMR spectrum, as well as two reso- cated by reports of [Cl3(Ph)Sb(μ-Cl)Sb(Ph)Cl3]3– as a bi-
nances at 159.2 and 152.5 ppm (corresponding to the CN3 metallic trianion, which retains a single chloride bridge.[26]
carbon atom) in the 13C{1H} NMR spectrum. These data It appears that the formation of two strong hydrogen bonds
indicate two different ligand environments and suggest that to the [hppH2]+ cation is sufficient to prevent the anion
one may be associated with a guanidinium component as from dimerizing through the chlorides in 3.
the low-field resonance in the proton NMR spectrum is
Considering a lone pair lying in the plane between N1
and Cl3, the geometry of Sb is best considered as distorted
typical for the NH atoms of the [hppH2]+ cation.[20]
X-ray diffraction analysis (Figure 8, Tables 1 and 4) octahedral, with Cl1 and Cl2 trans to one another [Cl1–Sb–
showed that 3 consists of the hydrogen-bonded ion pair Cl2 174.225(19)°] and a typically small bite angle for the
[hppH2][Sb(hpp)Cl3]. This salt may be considered as the net [hpp]– anion [N1–Sb–N2 61.00(6)°]. The difference in Sb–
result of a proton transfer between hppH molecules to af- N bond length [Sb–N1 2.2602(17) Å, Sb–N2 2.0756(17) Å]
844
www.eurjic.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 841–846

Antimony(III) Species Supported by a Bicyclic Guanidinate
that was purified by crystallization from THF at –20 °C. Yield
0.40 g, 37%. C14H24ClN6Sb (433.59): calcd. C 38.78, H 5.58, N
19.38; found C 38.67, H 5.61, N 19.30. 1H NMR (500 MHz,
CDCl3, 303 K): δ = 3.33 (m, 8 H, hpp-CH2), 3.11 (m, 8 H, hpp-
CH2), 1.91 (m, 8 H, hpp-CH2). 13C{1H} NMR (125 MHz, CDCl3,
300 K): δ = *, 46.3, 40.6, 23.8 (hpp-CH2) ppm; * resonance for
CN3 not observed.
is reflected in a shorter C1–N1 [1.320(3) Å] relative to C1–
N2 [1.357(3) Å] and is consistent with a large contribution
from the localized form of π-bonding (I/IЈ, Figure 5).[13]
The [hppH2]+ cation forms hydrogen bonds to Cl1 and
Cl3, with intermolecular Cl···HN distances of 2.51 and
2.52 Å, respectively. The C–N bond lengths within the core
are equivalent (within 3σ), indicating effective delocaliza-
tion of the positive charge. Similar hydrogen bonding be-
tween [hppH2]+ and metal halide anions have been recorded
for [CuCl4]2–[27] and [TaCl6]–.[28]
[hppH2][Sb(hpp)Cl3] (3): A solution of hppH (0.50 g, 3.6 mmol) in
THF (ca. 30 mL) was added dropwise to a solution of SbCl3
(0.41 g, 1.8 mmol) in THF (ca. 25 mL). A cloudy white precipitate
formed, which coagulated to a gummy solid over a period of 1 h.
Warming this mixture to approximately 60 °C and filtering af-
forded a colourless filtrate that was allowed to cool slowly to room
temperature, affording colourless crystals 3. Yield 0.19 g, 21%.
C14H26Cl3N6Sb (506.51): calcd. C 33.19, H 5.17, N 16.59; found C
Conclusions
In summary, we have demonstrated that the large size of
the Sb3+ ion enables the [hpp]– anion to bond through both
available nitrogen atoms as a chelating ligand. The structure
of both 1 and 2 indicate the presence of a stereochemically
active lone pair, which, in addition to the narrow bite angle
of the chelating guanidinate anion(s), generates highly dis-
torted metal geometries. We have also shown that simple
adduct formation with neutral hppH does not readily occur,
1
33.25, H 5.08, N 16.48. H NMR (300 MHz, CD3CN, 300 K): δ =
7.57 (br. s, 2 H, hppH2), 3.22 (m, 16 H, hpp-CH2), 1.92 (m, 8 H,
hpp-CH2) ppm. 13C{1H} NMR (75 MHz, CD3CN, 300 K): δ =
159.2, 152.5 (CN3), 47.1 (br), 40.7, 38.7, 24.1, 21.3 (hpp-CH2) ppm.
Crystallographic Data Collection and Refinement Procedures: De-
tails of the crystal data, intensity collection and refinement for
complexes 1, 2 and 3 are presented in Table 1. Crystals were cov-
ered in an inert oil, and suitable single crystals were selected under
the preferred mode of reactivity involving salt formation to a microscope and mounted on a Kappa CCD diffractometer. Data
was collected at 173(2) K with Mo-Kα radiation at 0.71073 Å. The
afford a rare monometallic five-coordinate antimonate(III)
anion.
structures were refined with SHELXL-97.[29]
CCDC-848242 (for 1), -848243 (for 2) and -848244 (for 3) contain
the supplementary crystallographic data for this paper. These data
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Experimental Section
General Procedures: All manipulations were carried out under dry
nitrogen with standard Schlenk line and cannula techniques or in
a conventional nitrogen-filled glovebox. Solvents were dried with
appropriate drying agents and degassed prior to use. NMR spectra
were recorded by using a Bruker Avance DPX 300 MHz spectrome-
ter at 300.1 (1H) and 75.4 (13C{1H}) MHz or a Varian VNMRS
500 MHz spectrometer at 500.1 (1H), 125.4 (13C{1H}) MHz. Pro-
ton and carbon chemical shifts were referenced internally to resid-
ual solvent resonances. Elemental analyses were performed by S.
Boyer at London Metropolitan University. Compounds hppH and
SbCl3 were purchased from Sigma–Aldrich and used as received.
Acknowledgments
We wish to thank the University of Sussex for funding (B. M. D.)
and Dr Nikos Tsoureas for collecting X-ray diffraction data for
compound 2.
[1] M. P. Coles, Dalton Trans. 2006, 985–1001.
[2] M. P. Coles, Chem. Commun. 2009, 3659–3676.
[3] P. J. Bailey, S. Pace, Coord. Chem. Rev. 2001, 214, 91–141.
[4] a) S. L. Aeilts, M. P. Coles, D. C. Swenson, R. F. Jordan, V. G.
Young Jr., Organometallics 1998, 17, 3265–3270; b) F. A. Cot-
ton, X. Feng, D. J. Timmons, Inorg. Chem. 1998, 37, 4066–
4069; c) M. P. Coles, P. B. Hitchcock, J. Chem. Soc., Dalton
Trans. 2001, 1169–1171; d) S. R. Foley, G. P. A. Yap, D. S.
Richeson, Polyhedron 2002, 21, 619–627; e) M. P. Coles, P. B.
Hitchcock, Organometallics 2003, 22, 5201–5211; f) M. D. Ir-
win, H. E. Abdou, A. A. Mohamed, J. P. Fackler Jr., Chem.
Commun. 2003, 2882–2883; g) M. P. Coles, P. B. Hitchcock, In-
org. Chim. Acta 2004, 357, 4330–4334; h) M. P. Coles, P. B.
Hitchcock, Chem. Commun. 2005, 3165–3167; i) C. Brink-
mann, F. García, J. V. Morey, M. McPartlin, S. Singh, A. E. H.
Wheatley, D. S. Wright, Dalton Trans. 2007, 1570–1572; j)
A. A. Mohamed, A. P. Mayer, H. E. Abdou, M. D. Irwin,
L. M. Pérez, J. P. Fackler Jr., Inorg. Chem. 2007, 46, 11165–
11172; k) G. Robinson, C. Y. Tang, R. Köppe, A. R. Cowley,
H.-J. Himmel, Chem. Eur. J. 2007, 13, 2648–2654; l) A. A. Mo-
hamed, H. E. Abdou, A. Mayer, J. P. Fackler Jr., J. Cluster Sci.
2008, 19, 551–559.
Sb(hpp)Cl2 (1): nBuLi in hexanes (1.8 mmol, 0.7 mL, 2.6 m) was
added dropwise to solution of hppH (0.252 g, 1.8 mmol) in THF
at –78 °C. The resultant mixture was warmed to ambient tempera-
ture and stirred for 1 h, after which time full conversion to the
lithium salt was assumed. The “hppLi” solution was added to
SbCl3 (0.413 g, 1.8 mmol) in THF (ca. 20 mL) at –78 °C to obtain
a colourless solution. The solution was warmed to ambient tem-
perature for 1 h, after which time a dark grey precipitate had
formed. The volatiles were removed under vacuum, and the prod-
uct was extracted with CH2Cl2. Yield 0.13 g, 22.3%. X-ray crystal-
lographic quality crystals were obtained by slowly cooling a hot
(ca. 70 °C) toluene solution to room temperature. C7H12Cl2N3Sb
(330.85): calcd. C 25.41, H 3.66, N 12.70; found C 25.49, H 3.53,
1
N 12.86. H NMR (500 MHz, CDCl3, 303 K): δ = 3.43, 3.23, 2.03
(m, 8 H, hpp-CH2) ppm. 13C{1H} NMR (125 MHz, CDCl3,
300 K): δ = *, 46.0, 39.9, 23.6 (hpp-CH2) ppm; * resonance for
CN3 not observed.
[5] a) F. A. Cotton, C. A. Murillo, D. J. Timmons, Polyhedron
1999, 18, 423–428; b) S. J. Birch, S. R. Boss, S. C. Cole, M. P.
Coles, R. Haigh, P. B. Hitchcock, A. E. H. Wheatley, Dalton
Trans. 2004, 3568–3574; c) M. P. Coles, P. B. Hitchcock, Eur. J.
Inorg. Chem. 2004, 2662–2672.
Sb(hpp)2Cl (2): Compound 2 was made by using the same synthetic
procedure as that described for 1, with hppH (0.648 g, 4.9 mmol), a
solution of nBuLi in hexanes (5.0 mmol, 2.0 mL, 2.5 m) and SbCl3
(0.560 g, 2.5 mmol). The product was isolated as a white powder
Eur. J. Inorg. Chem. 2012, 841–846
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
845

B. M. Day, M. P. Coles, P. B. Hitchcock
FULL PAPER
[6] a) S. R. Boss, M. P. Coles, R. Haigh, P. B. Hitchcock, R.
Snaith, A. E. H. Wheatley, Angew. Chem. 2003, 115, 5751; An-
gew. Chem. Int. Ed. 2003, 42, 5593–5596; b) S. R. Boss, M. P.
Coles, V. Eyre-Brook, F. García, R. Haigh, P. B. Hitchcock, M.
McPartlin, J. V. Morey, N. Hiroshi, P. R. Raithby, H. A.
Sparkes, C. W. Tate, A. E. H. Wheatley, Dalton Trans. 2006,
5574–5582.
[14] a) M. P. Coles, P. B. Hitchcock, Polyhedron 2001, 20, 3027–
3032; b) S. H. Oakley, M. P. Coles, P. B. Hitchcock, Inorg.
Chem. 2003, 42, 3154–3156; c) S. H. Oakley, M. P. Coles, P. B.
Hitchcock, Inorg. Chem. 2004, 43, 7564–7566; d) S. H. Oakley,
D. B. Soria, M. P. Coles, P. B. Hitchcock, Dalton Trans. 2004,
537–546; e) J. F. Berry, F. A. Cotton, P. Huang, C. A. Murillo,
X. Wang, Dalton Trans. 2005, 3713–3715; f) S. H. Oakley, D. B.
Soria, M. P. Coles, P. B. Hitchcock, Polyhedron 2006, 25, 1247–
1255; g) F. A. Cotton, J. P. Donahue, N. E. Gruhn, D. L. Licht-
enberger, C. A. Murillo, D. J. Timmons, L. O. Van Dorn, D.
Villagrán, X. Wang, Inorg. Chem. 2006, 45, 201–213; h) A. Pe-
ters, U. Wild, O. Hübner, E. Kaifer, H.-J. Himmel, Chem. Eur.
J. 2008, 14, 7813–7821; i) U. Wild, P. Roquette, E. Kaifer, J.
Mautz, O. Hübner, H. Wadepohl, H.-J. Himmel, Eur. J. Inorg.
Chem. 2008, 1248–1257; j) G. M. Chiarella, D. Y. Melgarejo,
A. Rozanski, P. Hempte, L. M. Perez, C. Reber, J. P. Fackler Jr.,
Chem. Commun. 2010, 46, 136–138.
[7] a) O. Ciobanu, P. Roquette, S. Leingang, H. Wadepohl, J.
Mautz, H.-J. Himmel, Eur. J. Inorg. Chem. 2007, 4530–4534;
b) R. Dinda, O. Ciobanu, H. Wadepohl, O. Hübner, R. Ach-
aryya, H.-J. Himmel, Angew. Chem. 2007, 119, 9270; Angew.
Chem. Int. Ed. 2007, 46, 9110–9113; c) O. Ciobanu, F. Allouti,
P. Roquette, S. Leingang, M. Enders, H. Wadepohl, H.-J. Him-
mel, Eur. J. Inorg. Chem. 2008, 5482–5493; d) O. Ciobanu, D.
Emeljanenko, E. Kaifer, J. Mautz, H.-J. Himmel, Inorg. Chem.
2008, 47, 4774–4778; e) O. Ciobanu, E. Kaifer, M. Enders, H.-
J. Himmel, Angew. Chem. 2009, 121, 5646; Angew. Chem. Int.
Ed. 2009, 48, 5538–5541.
[15] D. Gudat, T. Gans-Eichler, M. Nieger, Chem. Commun. 2004,
2434–2435.
[8] a) D. Kummer, S. H. A. Halim, W. Kuhs, G. Mattern, J. Or-
ganomet. Chem. 1993, 446, 51–65; b) S. H. Oakley, M. P. Coles, [16] A. Lipka, H. Wunderlich, Z. Naturforsch. Teil B 1980, 35,
P. B. Hitchcock, Dalton Trans. 2004, 1113–1114; c) S. H. Oak- 1548–1551.
ley, M. P. Coles, P. B. Hitchcock, Inorg. Chem. 2004, 43, 5168– [17] N. J. Hill, G. Reeske, J. A. Moore, A. H. Cowley, Dalton Trans.
5172; d) J. Maaranen, O. S. Andell, T. Vanne, I. Mutikainen,
J. Organomet. Chem. 2006, 691, 240–246; e) M. P. Coles, S. E.
Sözerli, J. D. Smith, P. B. Hitchcock, Organometallics 2007, 26,
6691–6693; f) M. P. Coles, S. M. El-Hamruni, J. D. Smith, P. B.
Hitchcock, Angew. Chem. 2008, 120, 10301; Angew. Chem. Int.
Ed. 2008, 47, 10147–10150; g) M. P. Coles, S. E. Sözerli, J. D.
Smith, P. B. Hitchcock, I. J. Day, Organometallics 2009, 28,
2006, 4838–4844.
[18] A. Lipka, Z. Naturforsch. Teil B 1983, 38, 341–346.
[19] N. Burford, E. Edelstein, J. C. Landry, M. J. Ferguson, R. Mc-
Donald, Chem. Commun. 2005, 5074–5076.
[20] M. S. Khalaf, S. H. Oakley, M. P. Coles, P. B. Hitchcock, Crys-
tEngComm 2008, 10, 1653–1661.
[21] S. K. Porter, R. A. Jaconson, J. Chem. Soc. A 1970, 1356–1359.
1579–1581; h) R. S. Ghadwal, K. Pröpper, B. Dittrich, P. G. [22] M. G. B. Drew, P. P. K. Claire, G. R. Willey, J. Chem. Soc., Dal-
Jones, H. W. Roesky, Inorg. Chem. 2011, 50, 358–364.
[9] R. D. Shannon, Acta Crystallogr., Sect. A 1976, 32, 751–767.
[10] a) C. Ergezinger, F. Weller, K. Dehnicke, Z. Naturforsch. Teil
B 1988, 43, 1119–1124; b) U. Patt-Seibel, U. Müller, C. Ergez-
inger, B. Borgsen, K. Dehnicke, D. Fenske, G. Baum, Z. Anorg.
Allg. Chem. 1990, 582, 30–36.
[11] a) F. Weller, J. Pebler, K. Dehnicke, K. Hartke, H.-M. Wolff,
Z. Anorg. Allg. Chem. 1982, 486, 61–69; b) W. Höneise, W.
Schwarz, G. Heckmann, A. Schmidt, Z. Anorg. Allg. Chem.
1986, 533, 55–64.
[12] a) P. J. Bailey, R. O. Gould, C. N. Harmer, S. Pace, A. Steiner,
D. S. Wright, Chem. Commun. 1997, 1161–1162; b) S. P. Green,
C. Jones, G. Jin, A. Stasch, Inorg. Chem. 2007, 46, 8–10; c) B.
Lyhs, S. Schulz, U. Westphal, D. Bläser, R. Boese, M. Bolte,
Eur. J. Inorg. Chem. 2009, 2247–2253.
[13] M. P. Coles, D. C. Swenson, R. F. Jordan, V. G. Young Jr., Or-
ganometallics 1997, 16, 5183–5194.
ton Trans. 1988, 215–218.
[23] A. T. Mohammed, U. Muller, Z. Naturforsch. Teil B 1985, 40,
562–564.
[24] S. Pohl, W. Saak, D. Haase, Angew. Chem. 1987, 99, 462; An-
gew. Chem. Int. Ed. Engl. 1987, 26, 467–468.
[25] M. Hall, D. B. Sowerby, J. Organomet. Chem. 1988, 347, 59–
70.
[26] W. S. Shedrick, C. Martin, Z. Naturforsch. Teil B 1992, 47,
919–924.
[27] I. Díaz, V. Fernández, J. L. Martínez, L. Beyer, A. Pilz, U.
Müller, Z. Naturforsch. Teil B 1998, 53, 933–938.
[28] D. B. Soria, J. Grundy, M. P. Coles, P. B. Hitchcock, Polyhedron
2003, 22, 2731–2737.
[29] G. M. Sheldrick, SHELXL-97, Program for the Refinement of
Crystal Structures, Göttingen, 1997.
Received: October 27, 2011
Published Online: January 9, 2012
846
www.eurjic.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 841–846