Preparation and properties of cyclic and open-chain Sb/N-donor ligands

Article abstract of DOI:10.1039/b909226a

The preparations of both open-chain and cyclic mixed-donor Sb/N ligands, MeN(CH₂-2-C₆H₄)₂SbMe (1), MeN(CH₂-2-C₆H₄SbMe₂)₂ (2), CH₂{CH₂N

Full text of DOI:10.1039/b909226a

View Article Online / Journal Homepage / Table of Contents for this issue
PAPER
www.rsc.org/dalton | Dalton Transactions
Preparation and properties of cyclic and open-chain Sb/N-donor ligands†
Marek Jura, William Levason, Gillian Reid and Michael Webster
Received 12th May 2009, Accepted 26th June 2009
First published as an Advance Article on the web 31st July 2009
DOI: 10.1039/b909226a
The preparations of both open-chain and cyclic mixed-donor Sb/N ligands, MeN(CH2-2-C6H4)2SbMe
(1), MeN(CH2-2-C6H4SbMe2)2 (2), CH2{CH2N(Me)CH2-2-C6H4SbMe2}2 (3) and CH2{CH2N(Me)-
CH2-2-C6H4}2SbMe (4), are described via reaction of chlorostibines with dilithio-reagents, and their
spectroscopic properties established. Air-stable stibonium derivatives of (3) and (4) have been isolated by
treatment of the compounds with excess MeI, which leads to quaternisation at the Sb atoms exclusively.
A crystal structure of a bis(stibonium) derivative of (3), [CH2{CH2N(Me)CH2-2-C6H4SbMe3}2]I2,
˚
reveals hypervalency at Sb through long-range Sb ◊ ◊ ◊ N interactions (ca. 2.87 A), giving
pseudo-five-membered rings fused to the aromatic rings, and distorted trigonal bipyramidal
coordination at Sb. The coordinating properties of compounds (1) to (4) have been investigated through
their reactions with Cu(I), Mn(I), Mo(0) and Pt(IV) reagents, and for (1) and (4) by reaction with Fe(0),
1
giving [Fe(CO)4(L)]. The spectroscopic data (IR, 1H, 13C{ H}, 55Mn, 63Cu, 95Mo and 195Pt NMR), mass
spectrometry and microanalyses for this series of complexes confirm that coordination occurs via the Sb
donor atoms in all cases, with N-coordination only present in fac-[Mn(CO)3(2)](CF3SO3). Crystal
structures of [Cu(2)2]BF4, [Mo(CO)4(2)] and [PtMe3I(2)] confirm the coordination modes, showing (2)
functioning as a wide-angle bidentate distibine. The structures also show the amine N-donor atoms in
˚
the complexes are involved in a hypervalent Sb ◊ ◊ ◊ N interaction (ca. 3.0 A) with one of the coordinated
Sb atoms in each ligand, leading to significant differences in the conformations of the carbon
backbones linking the Sb and N atoms. Reaction of Na3[RhCl6]·12H2O with one mol equiv. of (2), (3)
or (4) leads to the bis-ligand complex [RhCl2(2)2]Cl and the 1 : 1 Rh : L complexes [RhCl2(3)]Cl and
[RhCl3(4)], both of which involve coordination via the Sb and N donor atoms.
Ni-based catalytic polymerisation of styrene9 and norbornene in-
Introduction
sertion polymerisation.10 The occurrence of hypervalent bonding
Developments in the chemistry of stibine ligands have increased
in antimony chemistry is also of considerable current interest—
vide infra.11–14
significantly in recent years. Traditionally stibines (SbR3) were
considered to be poor ligands in comparison with the much
In recent work we have developed synthetic routes to new
more widely studied phosphines, and together with the practical
sterically demanding, wide-angled and chiral stibines, making
challenges presented by the reactivity of the Sb–C bonds (which
use of electrophilic reagents (R2SbCl) to introduce the stibine
can lead to Sb–C fission and/or scrambling of R groups) and
functions, and typically using Me substituents in order to increase
the lack of readily available organoantimony precursors (for
both the basicity and solubility of the resulting compounds (com-
pared to aryl groups).15–17 Higher denticity stibines are very rare—
the only tridentate being the (little studied) MeC(CH2SbPh2)3,18
while there are no reported examples of macrocycles involving
stibine functions. We have also reported the preparations of
the potentially tridentate O(CH2CH2SbR2)2 (R = Me or Ph),
which behave as bidentate Sb2-donor chelates to Cu(I), Ag(I)
(structural evidence for both), Rh(III) and Pt(II).19 A small number
of potentially tetradentate Sb2N2-donor analogues have been
described briefly, but no metal complexes are known.20
We report here the preparation and characterisation of a series
of new stibine ligands involving mixed Sb/N-donor sets and both
cyclic and open-chain structures, utilising ‘pre-organised’ reagents
to aid cyclisation and to promote chelation. The coordinating
properties of these compounds towards a selected range of
transition metals (Cu(I), Mo(0), Mn(I), Pt(IV), Rh(III)) has been
investigated in order to establish the preferred coordination modes
and donor properties of the geometrically constrained ligands.
These results are also described together with crystal structure
determinations of several examples.
antimony(III) only SbPh3 and SbX3, X = Cl, Br or I, are routinely
available commercially), this meant that they attracted limited re-
search interest.1–3 However, recent work4–9 has revealed important
differences in the chemistry of stibines compared to phosphines
and arsines. Significant findings include the first observation of
bridging SbiPr3 ligands in rhodium carbene complexes, which also
provide an entry into the corresponding PR3-bridged and AsR3-
bridged species (which have not been prepared directly).4 The
organometallic chemistry of platinum metal stibine complexes
has also received renewed interest, leading to different reaction
chemistry from the phosphine analogues,5,6 and several reports of
stibine complexes being used in catalysis, including Rh-catalysed
hydrosilylation using binaphthyl distibines,7,8 while the ‘poor’
s-donor properties of SbPh3 has been used to good effect in the
School of Chemistry, University of Southampton, Southampton, UK SO17
1BJ. E-mail: gr@soton.ac.uk
† CCDC reference numbers 731685–731688. For crystallographic data in
CIF or other electronic format see DOI: 10.1039/b909226a
This journal is
The Royal Society of Chemistry 2009
Dalton Trans., 2009, 7811–7819 | 7811
©

View Article Online
via a similar method, using the dibromodiamine reagent,
CH2{CH2N(Me)CH2-2-C6H4Br}2, which was obtained as a
colourless oil in moderate yield from reaction of N,N¢-dimethyl-
1,3-propanediamine with two mol equiv. of 2-bromobenzyl bro-
mide in CH2Cl2–pyridine at 0 ◦C. Following lithiation of this
compound, the SbMe2Cl was added dropwise as a toluene
solution, giving (3) as a yellow, air-sensitive oil in 52% isolated
yield, after hydrolysis, extraction and work-up. The EI mass
Results and discussion
Ligands
The methods employed for the preparations of the new mixed
Sb/N-donor ligands are shown in Scheme 1. The approach used
to prepare compound (1) is similar to that reported for a series
of stibocine derivatives, which have themselves been studied for
the rapid hypervalent antimony-mediated ethylylation of acyl
1
spectrum shows [(3) - Me]+ at m/z = 569. 1H and 13C{ H}
halides.13 Thus, reaction of MeN(CH2-2-C6H4Br)2 with BuLi
t
NMR spectra are readily assigned as (3). In order to establish
its identity unambiguously, a sample of (3) was converted to
the more stable bis-stibonium derivative, [CH2{CH2N(Me)CH2-
2-C6H4SbMe3}2]I2, by treatment with an excess of MeI in CH2Cl2
solution. The product is an air-stable white solid, and the spectro-
scopic and analytical data confirm that under these conditions
quaternisation occurs exclusively at the Sb atoms, leaving the
amine groups unchanged.
in diethyl ether at -78 ◦C gives the dilithiated intermediate,
MeN(CH2-2-C6H4Li)2, which was subsequently reacted with
either two mol equiv. of SbMe2Cl or one mol equiv. of SbMeCl2
(prepared by bubbling HCl (g) through a toluene solution of
SbMe2Ph or SbMePh2 respectively)16 over 18 h to give (1)
(MeN(CH2-2-C6H4)2SbMe) and (2) (MeN(CH2-2-C6H4SbMe2)2)
as off-white solids in 35 and 40% yield, respectively, following
hydrolysis, extraction and drying (MgSO4). Compound (2) is
rather more air-sensitive than (1), consistent with the presence
of two alkyl (Me) groups on Sb in the former cf. only one in
the latter. The EI mass spectra shows peaks with the correct
isotope distribution centred at m/z = 330 and 498 ([(1) - Me]+
and [(2) - Me]+ respectively), and microanalyses also support their
A crystal structure determination was also undertaken on
[CH2{CH2N(Me)CH2-2-C6H4SbMe3}2]I2·1/3CHCl3. The struc-
ture shows (Fig. 1, Table 1) a bis-stibonium dication, with
the free iodides balancing the charge. The Sb atoms are di-
rectly bonded to three terminal Me substituents as well as the
o-phenylene unit in the ligand backbone. There are additional
1
formulation as (1) and (2). The H NMR spectra of (1) and (2)
˚
weaker, hypervalent interactions (ca. 2.87 A) between Sb1 and
are consistent with the structures, the most notable features being
the SbMe protons which are observed at around 1 ppm—typical
N1 and between Sb2 and N2, giving pseudo-five-membered rings
linking each Sb to the adjacent N atom, leading to distorted
trigonal bipyramidal geometry at each Sb atom (the van der
1
of SbMe groups in related compounds.15,17,19 The 13C{ H} NMR
spectra are also consistent with the structures showing the highly
˚
Waals radii for N and Sb are 1.55 and 2.0 A, respectively).
shielded d(SbMe) at 1.2 and -1.3 ppm, respectively.
Hypervalency involving, for example, Sb ◊ ◊ ◊ N and Sb ◊ ◊ ◊ O con-
tacts has been well established in a variety of other systems,
especially those containing the 2-(R2NCH2)C6H4 group,11 e.g. [2-
˚
{Me2NCH2)C6H4}{(Me3Si)2CH}SbCl (d(Sb ◊ ◊ ◊ N) = 2.533(7) A),
and is also important in the reactivity of stibocine derivatives.13
Fig. 1 View of the structure of the dication in [CH2{CH2N(Me)CH2-
2-C6H4SbMe3}2]I2·1/3CHCl3 with numbering scheme adopted. Ellipsoids
are drawn at the 50% probability level and H atoms are omitted for clarity.
Symmetry operation: a = x, y, 1/2 - z.
◦
˚
Table 1 Selected bond lengths (A) and angles ( ) for [CH2{CH2N-
(Me)CH2-2-C6H4SbMe3}2]I2·1/3CHCl3
Sb1–C1
Sb1–C3
N1–C10
N1–C12
2.112(6)
2.101(6)
1.478(7)
1.470(7)
Sb1–C2
Sb1–C4
N1–C11
2.109(6)
2.119(5)
1.477(6)
C1–Sb1–C2
C1–Sb1–C4
C2–Sb1–C4
C11–N1–C10
C12–N1–C11
101.1(3)
117.1(2)
102.7(2)
109.5(4)
110.3(4)
C1–Sb1–C3
C2–Sb1–C3
C3–Sb1–C4
C12–N1–C10
115.0(2)
105.0(3)
113.3(2)
109.8(4)
Scheme 1 Preparative routes for compounds (1)–(4).
The preparation of the potentially tetradentate lig-
and (3) (CH2(CH2N(Me)CH2-2-C6H4SbMe2)2) was achieved
7812 | Dalton Trans., 2009, 7811–7819
This journal is
The Royal Society of Chemistry 2009
©

View Article Online
◦
˚
Very recently Breunig and co-workers have also studied hyperva-
Table 2 Selected bond lengths (A) and angles ( ) for [Cu(2)2]BF4
lency in compounds such as {2-(Me2NCH2)C6H4}2SbCH2SiMe3
Cu1–Sb1
Cu1–Sb3
2.5291(8)
2.5289(9)
Cu1–Sb2
Cu1–Sb4
2.5317(9)
2.5380(8)
˚
(R2SbCH2SiMe3) (d(Sb ◊ ◊ ◊ N) = 2.971(3), 3.189(3) A) and the
˚
related (R2Sb)2E (E = O; d(Sb ◊ ◊ ◊ N) = 2.775(5), 3.240(4) A;
12
˚
E = S; d(Sb ◊ ◊ ◊ N) = 2.855(3), 3.025(3) A). These are similar
Sb1–Cu1–Sb2
Sb1–Cu1–Sb4
Sb2–Cu1–Sb4
102.97(3)
115.61(3)
112.89(3)
Sb1–Cu1–Sb3
Sb2–Cu1–Sb3
Sb3–Cu1–Sb4
111.05(3)
108.42(3)
105.82(3)
to the distances found in [CH2(CH2N(Me)CH2-2-C6H4SbMe3)2]I2
within this work, although in the latter compound the Sb atoms
are formally cationic.
Simultaneous dropwise addition of solutions of the dilithiated
derivative of CH2{CH2N(Me)CH2-2-C6H4Br}2 and SbMeCl2 in a
1 : 1 mol ratio under similar conditions to those for ligand (1)
produces the SbN2-donor macrocycle (4) (CH2{CH2N(Me)CH2-
2-C6H4}2SbMe) in 62% yield as a colourless, waxy solid. Evidence
1
for this formulation follows from the 1H and 13C{ H} NMR
spectra, as well as the EI mass spectrum which shows peaks with
the correct isotope distribution corresponding to [(4)]+ (m/z =
416) and [(4) - Me]+ (m/z = 401). Treatment of this compound
with an excess of MeI in CH2Cl2 solution gave the stibonium
derivative [CH2{CH2N(Me)CH2-2-C6H4}2SbMe2]I as an air stable
white solid, which was characterised by H and 13C{ H} NMR
spectroscopy, showing the characteristic high frequency d(SbMe)
shifts associated with quaternisation at Sb, and electrospray mass
spectrometry which shows the only significant species at m/z =
431 [(4) + CH3]+. The ready formation of the cyclic species (1)
and (4) is attributed in part to the cis-directing influence (pre-
organisation) of the o-phenylene groups in the backbone. We have
recently utilised a similar strategy for the preparation of a range
of small ring selenoether macrocycles.21,22
1
1
Fig. 2 View of the structure of the cation in [Cu(2)2]BF4 with numbering
scheme adopted. Ellipsoids are drawn at the 50% probability level and H
atoms are omitted for clarity.
tetrahedron. The Cu–Sb distances are slightly longer than ob-
+
23
˚
served for [Cu{o-C6H4(CH2SbMe2)2}] (2.5021(5)–2.5222(5) A),
but shorter than those in [Cu(SbPh3)4]+ and [Cu{(p-FC6H4)3Sb}4]+
Complexes
involving the rather more weakly donating triarylantimony ligands
24
(av. 2.57 A). While the amine N-donor atoms in [Cu(2)2]+ are
˚
In order to probe the donor properties and the coordination modes
of these unusual Sb/N-donor ligands, we have investigated their
reactions with selected transition metal species and characterised
the products spectroscopically and in some cases crystallographi-
cally.
not involved in any interactions with the Cu atoms, there are
˚
weak, hypervalent interactions between Sb1 and N1 (3.04 A)
˚
˚
and Sb3 and N2 (3.00 A) (both ca. 1.0 A shorter than the
Sb2 ◊ ◊ ◊ N1 and Sb4 ◊ ◊ ◊ N2 distances and significantly shorter than
the sum of the van der Waals radii for N and Sb). These distances
are longer than d(Sb ◊ ◊ ◊ N) typically observed in neutral Sb(III)
systems showing hypervalency11–13 and also compared to those
in the stibonium cation [CH2{CH2N(Me)CH2-2-C6H4SbMe3)}2]2+
(vide supra), possibly due to steric factors.
The acyclic compounds (2) and (3) each react with one mol
equiv. of [Cu(NCMe)4]BF4 in EtOH–CH2Cl2 solution to give the
1 : 2 Cu : L complexes [Cu(2)2]BF4 and [Cu(3)2]BF4, respectively.
Copper-63 (I = 3/2, 69%) NMR spectroscopy provides a useful
technique through which to probe the solution speciation, since
the large quadrupole moment associated with the 63Cu nucleus
(Q = -0.211 ¥ 10-28 m2) dictates that only complexes with
essentially regular tetrahedral coordination give rise to a 63Cu
NMR resonance. Furthermore, previous work shows that Sb4-
coordination gives d(Cu) around -200 ppm.19,23 The 63Cu NMR
spectra of [Cu(2)2]BF4 and [Cu(3)2]BF4 show single resonances
at -203 and -234 ppm, respectively. Together with the 1 : 2
stoichiometry established from the microanalytical data, the
63Cu NMR data strongly suggest that these compounds involve
bidentate chelation of the stibine ligands.
Treatment of [Mo(CO)6] with one mol equiv. of (2) and
excess NaBH4 in degassed EtOH gives the tetracarbonyl species
[Mo(CO)4(2)] exclusively as a beige solid in good yield. The
presence of four terminal n(CO) vibrations in the IR spectrum
is strongly indicative of a cis-tetracarbonyl (C2v: 2a1 + b1 + b2) and
hence suggests bidentate chelation of (2), and the stretching fre-
quencies are similar to those for other known [Mo(CO)4(distibine)]
1
compounds.15,17,25,26 The 13C{ H} NMR spectrum shows two CO
1
1
resonances as expected and in both the H and 13C{ H} NMR
spectra only one d(Me) resonance is evident for [Mo(CO)4(2)]
and this is shifted to high frequency compared to (2) itself,
while the resonances associated with the NMe and NCH2 groups
are essentially unaffected. The 95Mo NMR spectrum shows one
resonance at -1729 ppm—typical of an Sb2(CO)4 environment at
Mo(0).15,17,25,26 Taken together, these data strongly suggest that
(2) is coordinated to Mo via the two stibine functions only.
Borohydride is effective in promoting CO substitution in Group 6
carbonyl chemistry, however the number of CO groups replaced is
Crystals of [Cu(2)2]BF4 were obtained by cooling the filtrate
from the reaction solution in the freezer (-18 ◦C) for several days.
The crystal structure shows (Fig. 2, Table 2) the Cu(I) coordinated
to a distorted tetrahedral arrangement of four Sb donor atoms
from the two molecules of (2), with no Cu ◊ ◊ ◊ N interactions.
˚
The Cu–Sb bond distances are in the range 2.529–2.538 A, while
the Sb–Cu–Sb angles involved in the chelate rings are 102.97(3)
and 105.82(3)◦—slightly less than those required for a regular
This journal is
The Royal Society of Chemistry 2009
Dalton Trans., 2009, 7811–7819 | 7813
©

View Article Online
dependent upon the particular system,18,26 although we note that
the tripodal MeC(CH2SbPh2)3 (L) forms the fac-[Mo(CO)3(L)]
exclusively.18
stability to the complex. The Sb atom involved in this interaction
is also the one giving the slightly longer Mo–Sb distance.
The Mn(I) compound [MnCl(CO)5] has been shown to re-
act with the distibines R2Sb(CH2)3SbR2 (R = Me or Ph) to
afford the neutral fac-[MnCl(CO)3(distibine)].27 In order to try
to promote tridentate Sb2N coordination of (2) we therefore
abstracted the Cl (via Ag(CF3SO3)) in acetone, prior to adding
(2). Using this approach we were able to isolate the product
[Mn(CO)3(2)](CF3SO3) on the basis of microanalysis. Electro-
spray MS shows peaks with the correct isotope distribution at
m/z = 693 ([Mn(CO)3(2)(MeCN)]+) and 652 ([Mn(CO)3(2)]+),
and IR shows n(CO) = 2011 and 1912, consistent with a fac-
tricarbonyl fragment,28 and conductivity measurements (CH2Cl2)
confirmed this compound as a 1 : 1 electrolyte, hence incorpo-
rating ionic [CF3SO3]-, and strongly suggesting tridentate Sb2N-
coordinated (2).
Confirmation of the coordination environment in [Mo(CO)4(2)]
follows from a crystal structure determination (Fig. 3, Table 3)
which shows the Mo atom in a distorted octahedral environ-
ment through four CO ligands and the two Sb donor atoms
from a bidentate molecule of (2), with d(Mo–Sb) = 2.7509(6),
◦
˚
2.7792(5) A. The chelate angle, Sb1–Mo1–Sb2 = 95.183(18) ,
is somewhat larger than observed in other distibine complexes
involving the Group 6 metal carbonyls, e.g. [Mo(CO)4(2,2¢-
bis(Me2Sb)-1,1¢-binaphthyl)] (84.13(4), 84.61(4)◦), although the
rigidity of the binaphthyl backbone is thought to have a significant
role here,17 and [W(CO)4({CH2(o-C6H4CH2SbMe2)}2)] (90.34(1)
to 93.26(1)◦).16 As expected, the Mo–C distances in [Mo(CO)4(2)]
fall into two distinct sets, those trans to Sb being significantly
shorter than those occupying axial (mutually trans) positions
reflecting the modest s-donor/p-acceptor properties of the stibine
compared to CO. The conformation of the ligand backbone in this
species is also interesting, adopting an arrangement which places
In previous work we have shown that PtMe3I is a very useful
reagent against which to probe the preferred coordination modes
of new ligands, with ligands favouring bidentate coordination
giving the neutral [PtMe3I(L2)] (e.g. in distibine complexes),19,29
whereas those favouring tridentate coordination can readily
displace the coordinated iodide, giving the ionic [PtMe3(L3)]I (as
for example in [PtMe3(Se3-macrocycle)]I).22 NMR spectroscopic
˚
˚
N1 ca. 1.0 A closer to Sb1 than Sb2, giving d(Sb1 ◊ ◊ ◊ N1) = 3.05 A;
this secondary (hypervalent) interaction presumably adds some
1
measurements (1H, 13C{ H} and 195Pt) allow these species to
be distinguished readily. Therefore, ligand (2) was reacted with
one mol equiv. of PtMe3I in refluxing CHCl3 to give a yellow
solid formulated as [PtMe3I(2)] on the basis of microanalysis.
The electrospray mass spectrum shows peaks with the correct
isotope distribution due to [PtMe3(2)]+ (m/z = 752). The 1H
1
and 13C{ H} NMR spectra each reveal two resonances due to
d(PtMe) groups, with 195Pt coupling, and also show that the
SbMe2 resonances are to high frequency of (2), while the NMe
and NCH2 resonances are unaffected. Finally, the 195Pt NMR
spectrum shows a single resonance at -4400 ppm, similar to
[PtMe3I(distibine)].19,29
The formulation of the product as neutral [PtMe3I(2)] is
confirmed from a crystal structure determination. The structure
shows (Fig. 4, Table 4) a distorted octahedral environment at Pt(IV)
Fig. 3 View of the structure of [Mo(CO)4(2)] with numbering scheme
adopted. Ellipsoids are drawn at the 50% probability level and H atoms
are omitted for clarity.
◦
˚
Table 3 Selected bond lengths (A) and angles ( ) for [Mo(CO)4(2)]
Mo1–C20
Mo1–C22
Mo1–Sb1
1.976(5)
2.063(6)
2.7792(5)
Mo1–C21
Mo1–C23
Mo1–Sb2
1.991(6)
2.027(6)
2.7509(6)
C20–Mo1–C21
C20–Mo1–C23
C21–Mo1–C23
C20–Mo1–Sb1
C21–Mo1–Sb1
C22–Mo1–Sb1
C23–Mo1–Sb1
Sb1–Mo1–Sb2
90.8(2)
86.4(2)
86.9(2)
177.01(16)
87.45(16)
85.97(14)
95.91(14)
95.183(18)
C20–Mo1–C22
C21–Mo1–C22
C22–Mo1–C23
C20–Mo1–Sb2
C21–Mo1–Sb2
C22–Mo1–Sb2
C23–Mo1–Sb2
91.6(2)
90.4(2)
176.6(2)
86.60(16)
177.36(16)
89.58(16)
93.04(15)
Fig. 4 View of the structure of [PtMe3I(2)] with numbering scheme
adopted. Ellipsoids are drawn at the 50% probability level and H atoms
are omitted for clarity.
7814 | Dalton Trans., 2009, 7811–7819
This journal is
The Royal Society of Chemistry 2009
©

View Article Online
◦
˚
of (1) and (4) with [Ni(CO)4]‡ in anhydrous CH2Cl2 proved to
be very unstable, darkening rapidly, and hence their identification
was uncertain and these were not pursued further. Reaction of
[Mo(CO)6] with (1) and excess NaBH4 in refluxing EtOH led
to a mixture of products irrespective of the ratio of Mo : (1)
used. IR spectroscopy showed n(CO) at 2070, 1987 and 1922 cm-1
(consistent with a pentacarbonyl species [Mo(CO)5(1)]; C4v theory:
2a1 + e) and 2017, 1945, 1904 and 1880 (consistent with cis-
tetracarbonyl species [Mo(CO)4(1)2]; C2v theory: 2a1 + b1 + b2).26
The compound [Fe(CO)4(4)] was obtained as a dark red solid
by reaction of [Fe2(CO)9] with one mol equiv. of (4) in thf–
CH2Cl2 (4 : 1). The product is assigned as an axially-substituted
Table 4 Selected bond lengths (A) and angles ( ) for [PtMe3I(2)]
Pt1–C20
Pt1–C21
Pt1–C22
2.105(7)
2.090(8)
2.092(7)
Pt1–Sb1
Pt1–Sb2
Pt1–I1
2.6321(7)
2.6053(7)
2.7972(7)
C20–Pt1–C21
C21–Pt1–C22
C20–Pt1–I1
C21–Pt1–I1
C22–Pt1–I1
C20–Pt1–Sb1
C21–Pt1–Sb1
C22–Pt1–Sb1
86.3(3)
86.7(3)
176.3(2)
92.0(2)
92.1(2)
95.2(2)
174.4(2)
88.2(2)
C20–Pt1–C22
Sb1–Pt1–Sb2
Sb1–Pt1–I1
84.6(3)
97.48(3)
86.14(2)
87.65(2)
95.5(2)
87.7(2)
174.3(2)
Sb2–Pt1–I1
C20–Pt1–Sb2
C21–Pt1–Sb2
C22–Pt1–Sb2
1
tbp containing k -Sb-coordinated (4) on the basis of the IR
via three Me ligands, an iodide and a bidentate Sb2-coordinated
data, which show three n(CO) peaks (C3v theory: 2a1 + e) at
1
similar frequencies to other stibine complexes.15,25 The H NMR
˚
(2), d(Pt–Sb) = 2.6053(7) and 2.6321(7) A; ∠(Sb1–Pt1–Sb2) =
97.48(3)◦. As in the other complexes of this ligand, in this moiety
spectroscopy shows small high frequency shifts for SbMe, with
1
˚
there is a similar hypervalent Sb1 ◊ ◊ ◊ N1 interaction (2.92 A);
the NMe resonances essentially unshifted. A k -Sb-coordinated
˚
the Sb2 ◊ ◊ ◊ N1 distance is much longer at 4.00 A. The Pt–Sb
[Fe(CO)4(1)] with similar spectroscopic properties was obtained
bond distances are similar to those in other stibine complexes
involving the Me3PtI fragment, although the chelate angle is
slightly larger.19,29 Again we note that the slightly longer Pt–Sb
distance in [PtMe3I(2)] is associated with Sb1, which shows the
hypervalent Sb ◊ ◊ ◊ N contact.
as a dark green oil.
Conclusions
The stibine compounds (1)–(3) have been isolated in moderate
yields by reacting the Sb-based electrophiles Me2SbCl or MeSbCl2
with appropriate dilithium reagents. Development of this method
has produced a very rare example of an Sb-containing macrocyclic
ring (4). The ligand properties of these new compounds towards a
range of transition metal species has been investigated and reveals
a tendency for them to coordinate via the Sb groups only in
the majority of reactions investigated. In the cases of (2) and
(3) this leads to bidentate chelation, confirmed spectroscopically
for Cu(I), Mo(0), Pt(IV) and Rh(III), and structurally for Cu(I),
Mo(0) and Pt(IV). The structures of these complexes and of
[CH2{CH2N(Me)CH2-2-C6H4SbMe3}2]I2 also show significant
hypervalent Sb ◊ ◊ ◊ N interactions. Structural evidence of hyper-
valent interactions in the metal complexes is unusual and has
not been found in complexes of hybrid P/N or As/N ligand
complexes. In some cases, specifically fac-[Mn(CO)3(2)](CF3SO3),
[RhCl2(3)]Cl and [RhCl3(4)], tetradentate (Sb2N2) and tridentate
(SbN2) coordination respectively is present.
We considered that the observation of only bidentate Sb2-
chelation in these complexes may reflect the preference for the
rather soft metals for antimony over the harder amine N atoms.
Therefore we have also investigated reaction of (2) and (3)
with Rh(III)—for which many amine complexes are known.30
Ligand (2) reacts with RhCl3·3H2O (1 : 1 mol ratio) in refluxing
EtOH to give a yellow solid formulated, on the basis of IR,
electrospray MS (m/z = 1201, [RhCl2(2)2]+) and microanalysis,
as the 1 : 2 complex [RhCl2(2)2]Cl. Metathesis of the anion with
NH4PF6 occurs easily, giving the corresponding [RhCl2(2)2]PF6,
and again under these conditions the Sb2N-donor ligand favours
bidentate Sb2-coordination, leading to a proposed Cl2Sb4 donor
set at Rh(III). Reaction of Na3[RhCl6]·12H2O with one mol
equiv. of (3) in refluxing EtOH leads to isolation of the 1 : 1
Rh : (3) complex [RhCl2(3)]Cl. This formulation follows from
microanalytical data and electrospray MS (MeCN: m/z = 757
1
[RhCl2(3)]+). The H NMR spectrum provides strong evidence
for coordination of the N-donor atoms, with d(NMe) shifted ca.
0.5 ppm to high frequency of that in (3) itself, and hence strongly
suggesting that (3) behaves as a tetradentate Sb2N2-donor ligand to
Rh(III).
Experimental
Infrared spectra were recorded as Nujol nulls between CsI discs
or in CH2Cl2 solution between NaCl plates using a Perkin-Elmer
983G or a Perkin-Elmer Spectrum 100 spectrometer over the range
Reaction of Na3[RhCl6]·12H2O with one mol equiv. of macro-
cyclic ligand (4) in EtOH–CH2Cl2 (6 : 1) produced an orange
solution from which the product [RhCl3(4)] was isolated as
a yellow–orange powder. The IR spectrum shows two peaks
attributed to n(Rh–Cl) at 321 and 311 cm-1, respectively, and con-
ductivity measurements confirm the product is a non-electrolyte.
4000–200 cm-1. 1H and 13C{ H} NMR spectra were recorded using
1
a Bruker AV300 spectrometer and are referenced to TMS. 55Mn,
63Cu, 95Mo and 195Pt NMR spectra were recorded using a Bruker
DPX400 spectrometer operating at 99.1, 106.1, 26.1 or 85.6 MHz
respectively and are referenced to external aqueous KMnO4,
[Cu(MeCN)4]BF4 in MeCN, aqueous Na2[MoO4] and 1 mol dm-3
Na2[PtCl6] respectively. Mass spectra were run by electron impact
on a VG-70-SE Normal geometry double focusing spectrometer
1
These measurements, together with H NMR spectroscopy and
microanalysis, support the proposed formulation of the product
as the neutral, six-coordinate complex fac-[RhCl3(4)].
In our previous work we have used transition metal carbonyl
complexes of new stibine ligands to probe their donor properties
1
by IR and 13C{ H} NMR spectroscopy. For the cyclic compounds
‡ CAUTION: Ni(CO)4 is volatile and extremely toxic. All reactions were
conducted in a good fume cupboard and in sealed equipment fitted with
bromine water scrubbers. Spectroscopic samples were also handled in a
fume cupboard and residues were destroyed with bromine water.
(1) and (4) we have therefore attempted to prepare complexes of
nickel, iron and molybdenum carbonyls in which coordination via
antimony only is anticipated. The products formed by reaction
This journal is
The Royal Society of Chemistry 2009
Dalton Trans., 2009, 7811–7819 | 7815
©

View Article Online
or by positive ion electrospray (MeCN solution) or APCI using a
VG Biotech platform. Microanalyses were undertaken by Medac
Ltd.
Solvents were dried by standard procedures prior to use and all
preparations were undertaken using standard Schlenk techniques
under a N2 atmosphere. The stibine ligands were stored and
handled in a glove box under N2. The precursor MeN(CH2-2-
C6H4Br)2 was prepared via the literature method.13
30 min, stirring for a further 20 min, and purging the solution with
N2 for 30 min. The chlorostibine solution was added dropwise
to the lithiated solution, and the reaction was stirred for 18 h.
The mixture was hydrolysed with degassed water (100 mL), the
organics separated and the aqueous washed with diethyl ether (2 ¥
50 mL). The combined organics were dried over MgSO4, filtered
and the volatiles removed under reduced pressure, yielding the title
compound as an off-white crystalline solid. Yield: 1.10 g, 40%. 1H
NMR (CDCl3): d 0.75 (s, SbCH3) [12H], 1.92 (s, NCH3) [3H],
3
3.72 (s, CH2) [4H], 7.28 (m, CH) [4H], 7.35 (d, J = 7 Hz, CH)
CH2{CH2N(Me)CH2-2-C6H4Br}2
3
1
[2H], 7.51 (d, J = 7 Hz, CH) [2H]. 13C{ H} NMR (CDCl3): d
-1.3 (SbCH3), 40.4 (NCH3), 64.5 (CH2), 127.3, 127.9, 129.3, 133.7
(CH), 138.9, 143.9 (Cipso). EIMS: m/z = 498 [(2) - Me]+. Required
for C19H27NSb2: C, 44.5; H, 5.3; N, 2.7. Found: C, 44.8; H, 5.3; N,
2.6%.
N,N¢-Dimethyl-1,3-propanediamine (5.10 g. 0.05 mol) and pyri-
dine (16 mL, 0.20 mol) were dissolved in CH2Cl2 (100 mL) and
the mixture was cooled to 0 ◦C. 2-Bromobenzyl bromide (25.0 g,
0.10 mol) was added as a CH2Cl2 solution (100 mL) dropwise, over
a period of 3 h. The reaction was stirred for 18 h, followed by the
addition of water (100 mL). The organics were separated, washed
with water (2 ¥ 50 mL), and dried over MgSO4. The solution was
filtered and the volatiles were removed under reduced pressure. The
crude product was then purified by silica column chromatography
(petroleum ether–CH2Cl2, 5 : 1) to yield the compound as a
CH2{CH2N(Me)CH2-2-C6H4SbMe2}2 (3)
Synthesised using the method for ligand (2) above, but using
the precursor CH2{CH2N(Me)CH2-2-C6H4Br}2, yielding a pale
yellow oil. Yield: 52%. 1H NMR (CDCl3): d 0.74 (s, SbCH3) [12H],
1.69 (m, CH2) [2H], 1.97 (s, NCH3) [6H], 2.37 (t, 3J = 7.5 Hz, CH2)
[4H], 3.46 (s, CH2) [4H], 7.05 (d, 3J = 6.5 Hz, CH) [2H], 7.16 (m,
1
colourless oil. Yield: 8.10 g, 37%. H NMR (CDCl3): d 1.75 (m,
CH2) [2H], 2.20 (s, CH3) [6H], 2.45 (t, CH2) [4H], 3.50 (s, CH2)
1
[4H], 7.00 (t, CH) [2H], 7.25 (t, CH) [2H], 7.35 (d, CH) [2H],
CH) [4H], 7.51 (d, 3J = 6.5 Hz) [2H]. 13C{ H} NMR (CDCl3): d
1
7.45 (d, CH) [2H]. 13C{ H} NMR (CDCl3): d 25.4 (CH2), 42.3
-1.1 (SbCH3), 23.8 (CH2), 40.1 (NCH3), 55.7, 65.0 (CH2), 127.2,
127.5, 128.5, 133.9 (CH), 139.3, 144.4 (Cipso). EIMS: m/z = 569
[(3) - Me]+.
(CH3), 55.9 (NCH2), 61.5(NCH2), 124.5 (Cipso), 127.2, 128.2, 130.8,
132.6 (CH), 138.6 (Cipso). EIMS: m/z = 441, [M]+. Required for
C19H24Br2N2: C, 51.8; H, 5.5; N, 6.4. Found: C, 51.6; H, 5.6; N,
6.2%.
[CH2{CH2N(Me)CH2-2-C6H4SbMe3}2]I2
Compound (3) (0.29 g, 0.5 mmol) was dissolved in degassed
acetone (50 mL) and an excess of MeI was added to the stirring
solution. The reaction was stirred for a further 2 h, before the
solution was reduced in volume to give a white precipitate. This
was collected by filtration, washed with cold acetone and dried in
vacuo. Yield: 0.35 g, 80%. 1H NMR (300 MHz, CDCl3): d 1.57 (m,
CH2) [2H], 2.10 (s, SbCH3) [18H], 2.22 (s, NCH3) [6H], 2.97 (br
m, CH2) [4H], 3.92 (br m, CH2) [4H], 7.46 (m, CH) [4H], 7.58 (m,
MeN(CH2-2-C6H4)2SbMe (1)
N1,N2 -Bis(2-bromobenzyl)-N1,N2 -dimethylpropane-1,3-diamine
(1.50 g, 3.40 m◦mol) was dissolved in diethyl ether (100 mL) and
n
cooled to -78 C. BuLi (1.6 M in hexane, 4.0 mL) was added
dropwise and the reaction was stirred for 2 h, and allowed to
warm to RT. SbMeCl2 was prepared by bubbling HCl (g) through
a toluene (100 mL) solution of SbMePh2 for 30 min, stirring for
a further 40 min, and purging the solution with N2 for 30 min.
The chlorostibine solution was added dropwise to the lithiated
solution, and the reaction was stirred for 18 h. The mixture was
hydrolysed with degassed water (100 mL), the organics separated
and the aqueous washed with diethyl ether (2 ¥ 50 mL). The
combined organics were dried over MgSO4, filtered and the
volatiles removed under reduced pressure, yielding (1) as an off-
white solid which was recrystallised from ethanol–CH2Cl2. Yield:
1
CH) [4H]. 13C{ H} NMR (CDCl3): d 6.8 (SbCH3), 22.4 (CH2),
42.6 (NCH3), 56.9, 63.2 (CH2), 130.0, 133.0, 136.1, 137.6 (CH),
145.4, 147.9 (Cipso). Electrospray MS (MeCN): m/z = 741 [(3) +
2CH3 + I]+, 599 [(3) + CH3]+, 307 [(3) + 2CH3]2+. Required for
C25H42I2N2Sb2: C, 34.6; H, 4.9; N, 3.2. Found: C, 35.1; H, 4.9; N,
3.2%.
CH2{CH2N(Me)CH2-2-C6H4}2SbMe (4)
1
0.41 g, 35%. H NMR (CDCl3): d 0.91 (s, SbCH3) [3H], 2.38 (s,
Synthesised using the method for ligand (2) above, but using the di-
bromodiamine precursor, CH2{CH2N(Me)CH2-2-C6H4Br}2. The
concentrations of lithiated precursor and the chlorostibine reagent
were kept below 0.025 mol dm-3, and the solutions of the reactants
were added slowly dropwise over a period of 3 h, yielding a pale
NCH3) [3H], 3.52–3.85 (m, CH2) [4H], 6.93–7.54 (m, CH) [8H].
1
13C{ H} NMR (CDCl3): d 1.20 (SbCH3), 41.3 (NCH3), 59.9 (CH2),
126.5, 127.2, 129.0, 132.6 (CH), 136.6, 143.5 (Cipso). EIMS: m/z =
330 [(1) - Me]+. Required for C16H18NSb·1/3CH2Cl2: C, 52.4; H,
5.0; N, 3.7. Found: C, 52.2; H, 5.4; N, 3.2%.
1
yellow solid. Yield: 62%. H NMR (CDCl3): d 1.16 (s, SbCH3)
[3H], 1.89 (m, CH2) [2H], 1.97 (s, NCH3) [6H], 2.21 (m, CH2) [4H],
MeN(CH2-2-C6H4SbMe2)2 (2)
1
3.55 (s, CH2) [4H], 7.05 (m, CH) [2H], 7.16 (m, CH) [6H]. 13C{ H}
MeN(CH2-2-C6H4Br)2 (2.00 g, 5.42 mmol) was dissolved in diethyl
NMR (CDCl3): d 1.65 (SbCH3), 22.3 (CH2), 41.1 (NCH3), 55.9,
65.6 (NCH2), 127.5, 127.7, 128.9, 136.4 (CH), 143.6, 145.0 (Cipso).
EIMS: m/z = 416 [(4)]+ (7%), 401 [(4) - Me]+ (60%). Required for
C20H27N2Sb: C, 57.5; H, 6.5; N, 6.7. Found: C, 57.1; H, 6.7; N,
5.9%.
◦
n
ether (100 mL) and cooled to -70 C. BuLi (1.6 M in hexane,
6.8 mL) was added dropwise and the reaction was stirred for 2 h,
and allowed to warm to RT. SbMe2Cl was prepared by bubbling
HCl (g) through a toluene (100 mL) solution of SbMe2Ph for
7816 | Dalton Trans., 2009, 7811–7819
This journal is
The Royal Society of Chemistry 2009
©

View Article Online
2012 (all s). Required for C23H27MoNO4Sb2: C, 38.3; H, 3.8; N,
1.9. Found: C, 38.2; H, 3.8; N, 2.0%.
[CH2{CH2N(Me)CH2-2-C6H4}2SbMe2]I
Compound (4) (0.21 g, 0.5 mmol) was dissolved in degassed
acetone (50 mL) and an excess of MeI was added to the stirring
solution. The reaction was stirred for 2 h, the solution was reduced
in volume and the resulting white precipitate was filtered off and
washed with cold acetone. Yield: 0.30 g, 86%. 1H NMR (CDCl3):
d 1.23 (s, SbCH3) [6H], 1.80 (m, CH2) [2H], 2.05 (s, NCH3) [6H],
[Mn(CO)3(2)][CF3SO3]
[Mn(CO)5Cl] (0.057 g, 0.25 mmol) was dissolved in acetone
(40 mL), AgCF3SO3 (0.064 g, 0.25 mmol) was added to the
solution which was then refluxed for 1 h. The solution was filtered
into a clean Schlenk tube and ligand (2) (0.128 g, 0.25 mmol) was
added as an acetone solution (15 mL) under N2. The mixture was
refluxed for 20 min and then stirred for 18 h. The volume was
reduced to ~10 mL in vacuo and the off-white solid filtered off
3.40 (m, CH2) [4H], 6.98 (m, CH) [6H]. 13C{ H} NMR (CDCl3): d
1
11.2 (SbCH3), 21.6 (CH2), 40.1 (NCH3), 54.4, 65.9 (NCH2), 129.2,
129.8, 130.1, 131.2 (CH). Electrospray MS (MeCN): m/z = 431
[(4) + CH3]+.
1
and dried under reduced pressure. Yield: 0.13 g, 65%. H NMR
(CDCl3): d 1.15 (s, SbCH3) [12H], 1.85 (s, NCH3) [3H], 3.48
(br, CH2) [4H], 6.95–7.54 (m, CH) [8H]. 55Mn NMR (CDCl3):
d -850 (w1/2 = 4200 Hz). Electrospray MS (MeCN): m/z =
693 [Mn(CO)3(2)(MeCN)]+, 652 [Mn(CO)3(2)]+. IR (Nujol/cm-1):
1912 (br), 2011 (s). Required for C23H27F3MnNO6SSb2: C, 34.5;
H, 3.4; N, 1.7. Found: C, 34.8; H, 3.8; N, 1.6%. Conductivity
measurement (1 ¥ 10-3 mol dm-3 in CH2Cl2): KM = 26 X-1 cm2 mol-1
(1 : 1 electrolyte).
[Fe(CO)4(1)]
Fe2(CO)9 (0.10 g, 0.29 mmol) was dissolved in dry thf (20 mL) and
filtered. Ligand (1) (0.10 g, 0.29 mmol) was added dropwise as a
CH2Cl2 solution (5 mL). On addition of the ligand the solution
turned a dark green colour and the reaction was left to stir for
15 h. The solvent was reduced to dryness and the dark green oil
1
was dried in vacuo. H NMR (CDCl3): d -0.10 (s, SbCH3) [3H],
2.72 (s, NCH3) [3H], 3.46–3.89 (m, CH2) [4H], 6.93–7.54 (m, CH)
1
[8H]. 13C{ H} NMR (CDCl3): d 4.4 (SbCH3), 34.4 (NCH3), 63.3
[PtMe3I(2)]
(CH2), 129.0, 129.3, 129.7 (CH), 136.6, 136.4, 138.9 (Cipso), 212.3
(CO). IR (CH2Cl2/cm-1): 2042 (s), 1966 (m), 1930 (br, s).
PtMe3I (0.100 g, 0.27 mmol) was dissolved in CHCl3 (10 mL),
ligand (2) (0.140 g, 0.27 mmol) was added as CHCl3 solution
(10 mL) under N2. The solution was stirred for 18 h, the volume
was then reduced to <5 mL and Et2O (10 mL) was added to
yield an off white precipitate. The solid was filtered off and dried
in vacuo and the filtrate was cooled to yield a crop of crystals.
[Cu(2)2]BF4
[Cu(MeCN)4]BF4 (0.094 g, 0.3 mmol) was dissolved in degassed
ethanol (70 mL) and ligand (2) (0.153 g, 0.3 mmol) was added
dropwise as a CH2Cl2 solution under N2. The reaction stirred at
room temperature for 4 h, after which the volume was reduced
to ca. 10 mL and the yellow solid formed was filtered, washed
with diethyl ether and dried in vacuo. Yield: 0.13 g, 74%. 1H
NMR (CDCl3): d 1.10 (s, SbCH3) [12H], 1.65 (s, NCH3) [3H],
1
Yield: 0.14 g, 58%. H NMR (CDCl3): d 0.88 (s, PtCH3) [3H]
(2JPtH= 73 Hz), 1.01 (br s, SbCH3) [6H], 1.27 (s, SbCH3) [6H],
1.40 (s, PtCH3) [6H] (2JPtH= 79 Hz), 2.08 (s, NCH3) [3H], 3.42
3
(br s, CH2) [4H], 7.31 (m, CH) [6H], 7.55 (d, J = 6.2 Hz) [2H].
1
13C{ H} NMR (CDCl3): d -10.33, -7.62 (SbCH3), -3.31 (1JPtC
=
3
724 Hz) (PtCH3), -1.24 (1JPtC = 616 Hz) (PtCH3), 44.62 (NCH3),
65.01 (CH2), 128.2, 129.4, 132.0, 136.1 (CH), 143.3 (Cipso). 195Pt
NMR (CDCl3): d -4400. Electrospray MS (MeCN): m/z = 752
[PtMe3(2)]+. Required for C22H36INPtSb2·CHCl3: C, 27.6; H, 3.7;
N, 1.4. Found: C, 27.7; H, 3.8; N, 1.4%.
3.44 (s, CH2) [4H], 6.95 (d, J = 8 Hz, CH) [2H], 7.31 (m, CH)
[4H], 7.54 (d, J = 8 Hz, CH) [2H]. 13C{ H} NMR (CDCl3):
3
1
d 1.81 (SbCH3), 41.5 (NCH3), 65.2 (CH2), 129.2, 129.3, 133.9
(CH), 159.9 (Cipso). 63Cu NMR (CHCl3–CDCl3): -203 (w1/2
=
2200 Hz). Electrospray MS (MeCN): m/z = 1089 [Cu(2)2]+, 617
[Cu(2)(MeCN)]+, 576 [Cu(2)]+, 514 [(2)]+, 360 [(2) - SbMe2]+.
Required for C38H54BCuF4N2Sb4: C, 38.8; H, 4.6; N, 2.4. Found:
C, 38.2; H, 4.6; N, 2.4%.
[RhCl2(2)2]Cl
Na3RhCl6·12H2O (0.15 g, 0.25 mmol) was dissolved in degassed
ethanol (40 mL), ligand (2) (0.13 g, 0.25 mmol) was added
dropwise as an ethanolic solution (50 mL) under N2, giving an
orange solution. The reaction mixture was stirred for a further
12 h, at which stage the solution was concentrated in vacuo,
producing a yellow solid which was filtered off, washed with
diethyl ether and dried in vacuo. Yield: 0.12 g, 78% (based on
(2)). 1H NMR (CDCl3): d 1.21 (s, SbCH3) [12H], 2.45 (br, s,
NCH3) [3H], 3.54–3.91 (m, CH2) [4H], 6.92–7.51 (m, CH) [8H].
Electrospray MS (MeCN): m/z = 1201 [RhCl2(2)2]+. Required
for C38H54Cl3N2RhSb4: C, 36.9; H, 4.4; N, 2.3. Found: C, 36.9;
H, 3.8; N, 2.4%. Addition of an EtOH solution of NH4PF6 to a
solution of [RhCl2(2)2]Cl, gave [RhCl2(2)2]PF6 as a yellow solid
which was collected by filtration, washed with EtOH and dried
in vacuo. Electrospray MS (MeCN): m/z = 1201 [RhCl2(2)2]+. IR
[Mo(CO)4(2)]
[Mo(CO)6] (0.053 g, 0.2 mmol), NaBH4 (0.017 g, 0.45 mmol) and
ligand (2) (0.205 g, 0.4 mmol) were suspended in ethanol (30 mL)
and heated to reflux for 1 h. The solution was stirred at room
temperature for 18 h and then reduced in volume (~5 mL) in vacuo.
Hexane (10 mL) was added and the suspension was stirred for 1 h.
The off-white solid was filtered off and dried in vacuo, the filtrate
was refrigerated to produce a crop of single crystals suitable for
1
X-ray structure analysis. Yield: 0.08 g, 55%. H NMR (CDCl3):
d 1.03 (s, SbCH3) [12H], 1.78 (s, NCH3) [3H], 3.55 (s, CH2) [4H],
7.17 (m, CH) [2H], 7.25 (m, CH) [4H], 7.46 (m, CH) [2H]. 13C{ H}
1
NMR (CDCl3): d 1.8 (SbCH3), 41.4 (NCH3), 64.5 (CH2), 128.2,
129.1, 131.6, 133.8 (CH), 135.2, 142.7 (Cipso), 210.8, 216.1 (CO).
95Mo NMR (CDCl3): d -1729. IR (Nujol/cm-1): 1860, 1882, 1909,
-
(Nujol/cm-1): 842 (s), 558 (s) (PF6 ).
This journal is
The Royal Society of Chemistry 2009
Dalton Trans., 2009, 7811–7819 | 7817
©

View Article Online
[Cu(3)2]BF4
under N2 for 48 h, giving an orange solution with an off-
white precipitate which was filtered off. The orange filtrate was
concentrated in vacuo (~10 mL) and the resulting yellow–orange
solid was collected by filtration, washed with a small volume of
cold CHCl3 and dried under reduced pressure. Yield: 0.103 g,
66%. 1H NMR (CDCl3): d 1.45 (br s, SbCH3) [3H], 1.85 (m,
CH2) [2H], 2.00 (s, NCH3) [6H], 2.35 (m, CH2) [4H], 3.70 (br s,
CH2) [4H], 6.80–7.55 (m, CH) [8H]. IR (Nujol/cm-1): 321 (s), 311
[Cu(MeCN)4]BF4 (0.094 g, 0.3 mmol) was dissolved in ethanol
(50 mL) and ligand (3) (0.175 g, 0.3 mmol) was added dropwise
as a CH2Cl2 solution (10 mL) under N2. The reaction was stirred
for 4 h, after which the volume was reduced to ca. 10 mL and
the beige solid formed was filtered off, washed with diethyl ether
1
and dried under reduced pressure. Yield: 0.14 g, 71%. H NMR
(CDCl3): d 1.21 (s, SbCH3) [12H], 1.92 (m, CH2) [2H], 2.43 (s,
NCH3) [6H], 2.80 (m, CH2) [4H], 3.55 (m, CH2) [2H], 4.07 (m, CH2)
[2H], 7.21 (m, CH) [2H], 7.37 (m, CH) [4H], 7.52 (m, CH). 63Cu
NMR (CHCl3–CDCl3): -234 (w1/2 = 5300 Hz). Electrospray MS
(MeCN): m/z = 647 [Cu(3)]+. Required for C46H72BCuF4N4Sb4:
C, 41.9; H, 5.5; N, 4.2. Found: C, 41.7; H, 5.4; N, 4.2%.
(m) (Rh–Cl). Required for C20H27Cl3N2RhSb·11 CHCl3: C, 32.1;
2
H, 3.6; N, 3.5. Found: C, 32.2; H, 3.6; N, 2.4%. Conductivity
measurement (1 ¥ 10-3 mol dm-3 in CH2Cl2): non-electrolyte
(KM < 1 X-1 cm2 mol-1).
[Fe(CO)4(4)]
Fe2(CO)9 (0.087 g, 0.24 mmol) was dissolved in dry thf (20 mL)
and filtered. Ligand (4) (0.10 g, 0.24 mmol) was added dropwise as
a CH2Cl2 solution (5 mL). On addition of the ligand the solution
turned a dark red colour and the reaction was left to stir for 15 h.
The solvent was reduced to dryness and the dark red solid was
[RhCl2(3)]Cl
Na3RhCl6·12H2O (0.150 g, 0.25 mmol) was dissolved in degassed
ethanol (40 mL), ligand (3) (0.146 g, 0.25 mmol) was added
dropwise as an ethanolic solution (50 mL) under N2, giving an
orange solution. The reaction mixture was stirred for a further
12 h at which stage the solution was concentrated in vacuo,
producing a yellow solid which was filtered off, washed with
1
dried in vacuo. H NMR (CDCl3): d 0.82 (s, SbCH3) [3H], 1.62–
2.30 (m, CH2) [6H], 1.80 (s, NCH3) [6H], 3.50 (br, CH2) [4H],
6.89–7.52 (m, CH) [8H]. IR (CH2Cl2/cm-1): 2038 (s), 1955 (sh),
1924 (vbr, s).
1
diethyl ether and dried in vacuo. Yield: 0.135 g, 68%. H NMR
(CDCl3): d 1.26 (br, SbCH3) [12H], 1.88 (m, CH2) [2H], 2.43
(br, NCH3) [6H], 2.89 (m, CH2) [4H], 3.50 (m, CH2) [2H], 4.07
(m, CH2) [2H], 7.11 (m, CH) [2H], 7.37 (m, CH) [4H], 7.59
(m, CH). Electrospray MS (MeCN): m/z = 757 [RhCl2(3)]+.
Required for C23H36Cl3N2RhSb2·1/2CH2Cl2: C, 36.5; H, 4.3; N,
3.2. Found: C, 36.3; H, 4.2; N, 3.6%. Conductivity measurement
(1 ¥ 10-3 mol dm-3 in CH2Cl2): KM = 18 X-1 cm2 mol-1 (1 : 1
electrolyte).
X-Ray crystallography
Details of the crystallographic data collection and refinement pa-
rameters are given in Table 5. Crystals of [CH2{CH2N(Me)CH2-2-
C6H4SbMe3}2]I2·1/3CHCl3 were obtained by cooling an acetone–
CHCl3 solution of the compound at -18 ◦C, while crystals of
[Cu(2)2]BF4, [Mo(CO)4(2)] and [PtMe3I(2)] were grown by cooling
the filtrates from the reaction mixtures at -18 ◦C. Data collection
used a Nonius Kappa CCD diffractometer (T = 120 K) and
with monochromated (graphite or confocal mirrors) Mo-Ka X-
[RhCl3(4)]
˚
Na3RhCl6·12H2O (0.15 g, 0.25 mmol) was dissolved in degassed
ethanol (60 mL), ligand (4) (0.21 g, 0.25 mmol) was added
dropwise as an CH2Cl2 solution (10 mL) under N2, and stirred
radiation (l = 0.71073 A). Structure solution and refinement
were routine31,32 except for the following compound, with H
atoms added to the model in calculated positions and using the
Table 5 Crystallographic parametersa
Compound
[Cu(2)2]BF4
[Mo(CO)4(2)]
[PtMe3I(2)]
[CH2{CH2N(Me)CH2-2-C6H4SbMe3}2]I2·1/3CHCl3
Formula
M
C38H54BCuF4N2Sb4
1176.18
C23H27MoNO4Sb2
720.90
C22H36INPtSb2
880.01
C25.33H42.33ClI2N2Sb2
907.70
Crystal system
Space group (no.)
Monoclinic
P21/c (14)
15.517(3)
20.044(4)
14.2102(15)
102.588(10)
4313.5(13)
4
3.003
53978
9867
0.096
Monoclinic
P21/n (14)
9.9439(10)
7.1462(10)
36.806(5)
97.694(5)
2591.9(6)
4
2.573
21865
5554
0.044
Monoclinic
P21/c (14)
16.843(4)
10.645(3)
15.405(3)
110.431(15)
2588.2(10)
4
8.665
29377
5919
0.068
Hexagonal
P63/m (176)
13.7732(10)
13.7732(10)
29.544(3)
90
4853.6(7)
6
3.676
28258
3789
0.095
162
˚
a/A
˚
b/A
˚
c/A
b/◦
U/A
Z
3
˚
m(Mo-Ka)/mm-1
No. data collected
No. unique data
Rint
No. parameters
R1, wR2 (I > 2s(I))b
R1, wR2 (all data)
461
0.050, 0.083
0.090, 0.095
285
0.044, 0.101
0.049, 0.104
252
0.042, 0.095
0.065, 0.104
0.034, 0.064
0.051, 0.069
ꢀ
ꢀ
ꢀ
Details in common: temperature = 120 K; wavelength (Mo-Ka) = 0.71073 A; qmax = 27.5◦. b R1 = ꢀFo| - |Fcꢀ/ |Fo|; wR2 = [ w(Fo
-
a
2
˚
ꢀ
Fc2)2/ wFo
] .
4
1/2
7818 | Dalton Trans., 2009, 7811–7819
This journal is
The Royal Society of Chemistry 2009
©

View Article Online
11 For examples see: Y. Yamamoto, X. Chen, S. Kojima, K. Ohdoi, M.
Kitano, Y. Doi and K. Akiba, J. Am. Chem. Soc., 1995, 117, 3922;
S. Kamepalli, C. J. Carmalt, R. D. Culp, A. H. Cowley, R. A. Jones
and N. C. Norman, Inorg. Chem., 1996, 35, 6179; C. J. Carmalt, A. H.
Cowley, R. Culp, R. A. Jones, S. Kamepalli and N. C. Norman, Inorg.
Chem., 1997, 36, 2770; H. J. Breunig, I. Ghesner, M. E. Ghesner and
E. Lork, Inorg. Chem., 2003, 42, 1751; L. M. Opris, A. Silvestru, C.
Silvestru, H. J. Breunig and E. Lork, Dalton Trans., 2003, 4367.
12 L. M. Opris, A. M. Preda, R. A. Varga, H. J. Breunig and C. Silvestru,
Eur. J. Inorg. Chem., 2009, 1187.
default C–H distance. The hexagonal [CH2{CH2N(Me)CH2-2-
C6H4SbMe3}2]I2·1/3CHCl3 was eventually solved in the lower
symmetry Laue group although all of the possible space groups
arising from the systematic absence showed promisingly low
CFOM values. The space group P63/m (no. 176) together with
the Shelxl TWIN command provided a satisfactory solution. The
iodide ions required for charge balance arise from I1 (4f site), I2
(6h) and I3 (4e, and sof 0.5) with a partial CHCl3 solvate molecule
located in the vicinity of I3. Selected bond lengths and angles are
given in Tables 1–4.
13 N. Kakusawa, Y. Tobiyasu, S. Yasuike, K. Yamaguchi, H. Seki and J.
Kurita, J. Organomet. Chem., 2006, 691, 2953.
14 M. D. Brown, W. Levason, G. Reid and M. Webster, Dalton Trans.,
2006, 4039.
15 W. Levason, M. L. Matthews, G. Reid and M. Webster, Dalton Trans.,
2004, 51.
Acknowledgements
16 M. D. Brown, W. Levason, G. Reid and M. Webster, Dalton Trans.,
We thank the EPSRC (EP/D003148/1) for support and Johnson-
Matthey plc for generous loans of precious metal salts.
2006, 5648.
17 M. Jura, W. Levason, G. Reid and M. Webster, Dalton Trans., 2008,
5774.
18 A. F. Chiffey, J. Evans, W. Levason and M. Webster, Organometallics,
1996, 15, 1280.
References
19 M. F. Davis, M. Jura, W. Levason, G. Reid and M. Webster,
J. Organomet. Chem., 2007, 692, 5589.
1 W. Levason and G. Reid, in Comprehensive Coordination Chemistry II,
ed. J. A. McCleverty and T. J. Meyer, Elsevier, Amsterdam, 2004, vol.
1, p. 377.
20 W. Levason, B. Sheikh and W. E. Hill, J. Organomet. Chem., 1981, 219,
163.
2 W. Levason and N. R. Champness, Coord. Chem. Rev., 1994, 133,
21 W. Levason, J. M. Manning, M. Nirwan, R. Ratnani, G. Reid, H. L.
Smith and M. Webster, Dalton Trans., 2008, 3486.
22 W. Levason, J. M. Manning, G. Reid, M. Tuggey and M. Webster,
Dalton Trans., 2009, 4569.
23 W. Levason, M. L. Matthews, G. Reid and M. Webster, Dalton Trans.,
2004, 554.
115.
3 W. Levason and G. Reid, Coord. Chem. Rev., 2006, 250,
2565.
4 H. Werner, Angew. Chem., Int. Ed., 2004, 43, 938.
5 H. Werner, D. A. Ortmann and O. Gevert, Chem. Ber., 1996, 129,
411; H. Werner, C. Gru¨nwald, P. Steinert, O. Gevert and J. Wolf,
J. Organomet. Chem., 1998, 565, 231; M. Manger, J. Wolf, M.
Laubender, M. Teichert, D. Stalke and H. Werner, Chem.–Eur. J.,
1997, 3, 1442; E. Bleuel, O. Gevert, M. Laubender and H. Werner,
Organometallics, 2000, 19, 3109; D. A. Ortmann, B. Weberndo¨rfer, J.
Scho¨neboom and H. Werner, Organometallics, 1999, 18, 952.
6 D. A. Ortmann, B. Weberndo¨rfer, K. Ilg, M. Laubender and H. Werner,
Organometallics, 2002, 21, 2369; H. Werner, P. Schwab, A. Heinemann
and P. Steinert, J. Organomet. Chem., 1995, 496, 207; D. A. Ortmann,
O. Gevert, M. Laubender and H. Werner, Organometallics, 2001, 20,
1776.
24 G. A. Bowmaker, R. D. Hart, J. D. Kildea, E. N. de Silva, B. W. Skelton
and A. H. White, Aust. J. Chem., 1997, 50, 539; A. Baida, F. H. Jardine,
R. G. Willett and K. Emerson, Inorg. Chem., 1991, 30, 1365.
25 M. D. Brown, W. Levason, J. M. Manning and G. Reid, J. Organomet.
Chem., 2005, 690, 1540; A. M. Hill, W. Levason, M. Webster and I.
Albers, Organometallics, 1997, 16, 5641.
26 A. M. Hill, N. J. Holmes, A. R. J. Genge, W. Levason, M. Webster and
S. Rutschow, J. Chem. Soc., Dalton Trans., 1998, 825; T. Campbell,
A. M. Gibson, R. Hart, S. D. Orchard, S. J. A. Pope and G. Reid,
J. Organomet. Chem., 1999, 592, 296.
27 S. J. A. Pope and G. Reid, J. Chem. Soc., Dalton Trans., 1999, 1615.
28 J. Connolly, A. R. J. Genge, W. Levason, S. D. Orchard, S. J. A. Pope
and G. Reid, J. Chem. Soc., Dalton Trans., 1999, 2334.
29 M. D. Brown, W. Levason, G. Reid and M. Webster, Dalton Trans.,
2006, 1667.
30 See P. S. Sheridan, in Comprehensive Coordination Chemistry I, ed.
G. Wilkinson, R. D. Gillard and J. A. McCleverty, Pergamon, Oxford,
1987, vol. 4, p. 901.
7 S. Yasuike, S. Okajima, K. Yamaguchi and J. Kurita, Tetrahedron Lett.,
2003, 44, 6217.
8 S. Yasuike, S. Okajima, K. Yamaguchi, H. Seki and J. Kurita,
Tetrahedron, 2003, 59, 4959; S. Yasuike, S. Okajima, K. Yamaguchi,
H. Seki and J. Kurita, Tetrahedron: Asymmetry, 2000, 11, 4043.
9 M. Jimenez-Tenorio, M. C. Puerta, I. Salcedo, P. Valerga, S. I. Costa,
P. T. Gomes and K. Mereiter, Chem. Commun., 2003, 1168; M. Jimenez-
Tenorio, M. C. Puerta, I. Salcedo, P. Valerga, I. de los Rios and K.
Mereiter, Dalton Trans., 2009, 1842.
31 G. M. Sheldrick, SHELXS-97, program for crystal structure solution,
University of Go¨ttingen, Germany, 1997.
10 J. A. Casares, P. Espinet, J. M. Martin-Alvarez, J. M. Martinez-Ilarduya
and G. Salas, Eur. J. Inorg. Chem., 2005, 3825.
32 G. M. Sheldrick, SHELXL-97, program for crystal structure refinement,
University of Go¨ttingen, Germany, 1997.
This journal is
The Royal Society of Chemistry 2009
Dalton Trans., 2009, 7811–7819 | 7819
©