Group 13 metal(I) and (II) guanidinate complexes: Effect of ligand backbone on metal oxidation state and coordination sphere

Article abstract of DOI:10.1039/b718799h

Reactions of lithium salts of the bulky guanidinate and phosphaguanidinate ligands, [ArNC(ER₂)NAr]^- (ER₂ = NPr ⁱ₂ (Priso^-), cis-NC₅H ₈Me₂-2,6 (Pipiso^-<

Full text of DOI:10.1039/b718799h

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PAPER
www.rsc.org/njc | New Journal of Chemistry
Group 13 metal(I) and (II) guanidinate complexes: effect of ligand
backbone on metal oxidation state and coordination spherewz
Guoxia Jin,b Cameron Jones,*ab Peter C. Junk,a Andreas Staschab and
William D. Woodula
Received (in Durham. UK) 5th December 2007, Accepted 7th February 2008
First published as an Advance Article on the web 14th March 2008
DOI: 10.1039/b718799h
Reactions of lithium salts of the bulky guanidinate and phosphaguanidinate
ligands, [ArNC(ER2)NAr]ꢀ (ER2 = NPri2 (Prisoꢀ), cis-NC5H8Me2-2,6 (Pipisoꢀ) or
P(C6H11)2 (PGisoꢀ); Ar = C6H3Pri2-2,6), with group 13 metal(I) halides have been carried out.
All reactions with TlBr led to monomeric thallium(I) complexes, [Tl{ArNC(ER2)NAr}],
in which the ligand chelates the metal in an N,arene-fashion. The reactions with InCl led
to mixed results and the isolation of the dimeric indium(II) complexes, [{InCl(Priso)}2] and
[{InCl(Pipiso)}2], and the monomeric indium(I) species, [In(Pipiso)] and [In(PGiso)].
The ligands of the latter two complexes exhibit differing coordination modes in the
solid state, namely N,N0-chelating and N,arene-chelating, respectively. The reactions
with ‘‘GaI’’ were less successful and gave only low yields of the poorly characterised
gallium(II) complexes, [{GaI(Priso)}2] and [{GaI(Pipiso)}2]. This study has shown
that the related ligand, [ArNC{N(C6H11)2}NAr]ꢀ (Gisoꢀ) is superior for the stabilisation
of group 13 metal(I) complexes. The oxidative additions of I2 or SiMe3I to one
such complex, [Ga(Giso)], yielded the gallium(III) compounds, [GaI2(Giso)] and
[GaI(SiMe3)(Giso)].
and their coordination and other chemistry has been widely
explored.2,10
Introduction
The low oxidation state chemistry of all the group 13 metals is
now well developed.1–5 In this field sterically bulky amide
bulky guanidinates and amidinates as potentially chelating ligands
One of our contributions to this area centres on the use of
for the formation of group 13 metal(I) amides.11–15 Preliminary
ligands have proved especially useful for the stabilisation of
complexes with the group 13 metals in either the +1, +2 or
studies have suggested that the metal involved, and subtle changes
mixed oxidation states. The vast majority of such complexes
to the steric and electronic properties of the enlisted ligands,
are, however, polynuclear. Recent efforts have been directed
can lead to significant variations in the complex type obtained.
towards the formation of mononuclear metal(I) amide
For example, when alkali metal salts of the bulky guanidinate
ligand, [ArNC{N(C6H11)2}NAr]ꢀ Gisoꢀ (Ar = C6H3Pri2-2,6),
systems as these possess a stereochemically active singlet lone
pair at the metal which can lead to their use as unconventional
were reacted with metal(I) halides, either N,N0- or N,arene-che-
lated complexes (3–5, respectively) were obtained.11 Apparently,
Lewis bases in the formation of heterometallic
species. Although bulky monodentate amides, e.g. –N(SiMe3)-
the larger size of the metal in 5 circumvents N,N0-chelation by
the small bite angle Gisoꢀ ligand in that case. Similar reactions
{C6H3(C6H2Me3-2,4,6)2-2,6}, have rarely been used to prepare
monomeric metal(I) amides,6 chelating amides, e.g.
with salts of the less bulky, less N-electron rich amidinate,
b-diketiminates7 (as in 18) and doubly reduced diazabuta-
dienes (as in 29), are more commonly employed for this task.
Complexes 1 and 2 have been described as group 13 analogues
of the important N-heterocyclic carbene (NHC) class of ligand
[ArNC(But)NAr]ꢀ (Pisoꢀ), led to different outcomes,
namely the formation of the indium or thallium N,arene-chelated
complexes, 6 and 7 (which co-crystallise with the free ligand,
PisoH), and the dimeric gallium(II) complex, 8; the latter via
disproportionation.12,13 The differences here probably result from
the smaller backbone substituent on Pisoꢀ (relative to Gisoꢀ)
which reduces its propensity to form the N,N0-chelated isomers
of 6 and 7. In addition, the smaller ligand presumably
provides less protection towards disproportionation of the likely
a Monash University, School of Chemistry, PO Box 23, VIC, 3800,
Australia
b Cardiff University, School of Chemistry, Main Building, Cardiff, UK
CF10 3AT
w Dedicated to Professor Jerry Atwood on the occasion of his 65th
birthday.
gallium(I) intermediate to
8
(viz. [Ga(Piso)]), than Gisoꢀ
provides for 3. Considering that 3 and 4 have shown utility as
‘‘NHC like’’ ligands in the formation of novel transition metal
complexes,16 we wished to further explore the effect that the
backbone substituent of guanidinate and phosphaguanidinate
ligands, [ArNC(ER2)NAr]ꢀ (E = N or P), has on the nature of
z Electronic supplementary information (ESI) available: Synthesis,
spectroscopic and crystallographic data for [InCl{ArNC-
(p-C6H4Me)NAr}2]ꢁ(hexane). ORTEP diagram for 15. Crystallo-
graphic data for compounds 9–16. CCDC reference number 677872
and 679098–679104. For crystallographic data in CIF or other elec-
tronic format see DOI: 10.1039/b718799h
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their complexes with low oxidation state group 13 centres. The
results of this study are reported herein.
Scheme 1 Reagents: (i) TlBr, toluene, ꢀLiBr.
dinate ligand chelates the thallium(I) centre in an N,arene-
fashion (cf. 5 and 7). The 1H and 13C NMR spectra of 9 and 10
are more symmetrical than expected and exhibit broad, poorly
resolved signals. A similar observation was made for the
spectra of 5.11 In that case it was suggested that a fluxional
process was occurring in solution at room temperature
in which the thallium centre exchanges between the two
N-centres of the ligand. It is not known if this occurs via. an
N,N-chelated intermediate but the exchange must be a low
energy process as the NMR spectra of 5 (and 9 and 10)
remained largely unchanged down to ꢀ90 1C. In contrast,
the spectra for 11 are well resolved and are consistent with its
proposed structure, as has previously been reported to be the
case for the amidinate complex, 7.12 These differences likely
result from the fact that the guanidinate ligands of 5, 9 and 10
(unlike the amidinate and phosphaguanidinate ligands of 7
and 11, respectively) have resonance structures possessing two
C–NAr single bonds, viz. [R2N+QC{C–NꢀAr}2], thus facil-
itating their isomerisation by rotation about these bonds.
The X-ray crystal structures of 9–11 were all determined and
their molecular structures are depicted in Fig. 2. Two crystal-
lographically independent molecules were refined in the asym-
metric unit of the structure of 10. As these exhibit very similar
metrical parameters, comment on the geometry of only one
will be passed here. The thallium centre of each monomeric
complex is coordinated in an Z1-fashion by the amido centre
(N(1)) of its guanidinate ligand. The metal also has an
approximately Z3-interaction with the aryl substituent of
N(2). An examination of the magnitudes of the C(1)–N bond
lengths of the guanidinate ligands suggests a low degree of
delocalisation over their N3C backbones (see Table 1). As
these structures are closely related to those of 5 and 7, it seems
that for thallium(I), N,arene-chelation of the metal by the
ligand is certainly preferred over N,N0-chelation, which has
previously been exhibited by the smaller gallium(I) and
indium(I) centres of 3 and 4. In addition, in the preparation
of all thallium(I) complexes in this study, there has been
no evidence of disproportionation processes leading to thal-
lium(II) or (III) complexes. This is in line with the redox
stability of thallium(I), relative to that of indium(I) and
gallium(I).
Results and discussion
In the early stages of this study a range of amidinate salts,
M[ArNC(R)NAr]ꢀ (M = Li, Na or K; R = alkyl or aryl),
were reacted with indium(I) and gallium(I) halides. Despite the
bulky N-aryl substituents of the amidinates used, these reac-
tions almost exclusively led to disproportionation and the
formation of metal(III) amidinate complexes, e.g.
[InIIICl{ArNC(p-C6H4Me)NAr}2],17 unless the amidinate
backbone substituent was a tertiary alkyl group, e.g. as in 6.
As a result, attention shifted to guanidinate ligands that have a
similar steric bulk to the Gisoꢀ ligand, the stabilising proper-
ties of which have already been demonstrated. The ligands
chosen for this study are depicted in Fig. 1. Prisoꢀ was
chosen to examine the effect a slight reduction in guanidinate
backbone bulk (relative to Gisoꢀ) would have on the outcome
of its reactions with group 13 halides. Pipisoꢀ (the steric bulk
of which is intermediate between that of Prisoꢀ and Gisoꢀ)
was chosen as it was expected to introduce a degree of
asymmetry to its group 13 complexes. PGisoꢀ was chosen as
its PCy2 substituent is pyramidal as opposed to the planar
NCy2 group of Gisoꢀ. Consequently, its P-lone pair cannot
participate in delocalised p-bonding within the ligand
backbone, as the corresponding N-lone pair of Gisoꢀ can
potentially do.
The reactions of TlBr with lithium salts of Prisoꢀ, Pipisoꢀ
and PGisoꢀ were carried out and all led to the formation of
monomeric complexes, 9–11 (Scheme 1), in which the guani-
The reactions of lithium salts of the guanidinates used in
this study with InCl led to more diverse outcomes than those
with TlBr. Disproportionation (as evidenced by In metal
deposition) occurred in the reaction with Li[Priso] to give a
low to moderate yield of the indium(II) dimeric complex, 12,
and a significant amount of the free guanidine, PrisoH
(Scheme 2). Disproportionation was also evident in the
Fig. 1 Ligands used in this study.
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Fig. 2 Molecular structures of (a) 9, (b) 10 and (c) 11 (25% thermal ellipsoids are shown; hydrogen atoms omitted for sake of clarity).
reaction with Li[Pipiso] which afforded a low yield of the
indium(II) complex, 13, but also the N,N0-chelated indium(I)
complex, 14. An indium(I) complex, 15, was the only isolated
product from the reaction with Li[PGiso], but in this case it
was isolated as the N,arene-chelated isomer.
included in the supplementary material, though relevant me-
trical parameters for this compound are included in Table 1.
These show the phosphaguanidinate ligand to be effectively
localised. The structures of both 12 and 13 reveal them to be
dimeric (cf. the structure of 8) with similar InII–InII distances
that lie within the normal range18 and can be compared with
related complexes, e.g. [{InIICl[ArNC(H)C(H)NAr]}2]
(2.7280(9) A19). In addition, the In-N distances in both com-
plexes are unexceptional (cf. 2.168 A mean in [{InIICl-
[ArNC(H)C(H)NAr]}2]19) and the atom separations within
the coordinated NCN fragments of the complexes are sugges-
tive of significant delocalisation. The backbone amino sub-
stituents of the guanidinate ligands are removed from being
co-planar with their attached indium heterocycles (dihedral
angles between least squares planes: 12 = 27.5, 13 = 32.31
mean) which leads to a lower degree of delocalisation of their
N-lone pairs into the guanidinate framework than would be
expected if they were co-planar. This is manifested by sig-
nificantly longer bonds from the backbone carbon centres to
the amino N-atoms than to the metal coordinated nitrogens.
The structure of 14 is very similar to that of 4. It possesses a
two-coordinate indium centre that has no significant inter- or
intramolecular interactions. The indium coordinated NCN
These results highlight the more redox active nature of
indium(I) than thallium(I) and show that subtle differences in
ligand sterics can have a significant effect on the product
formed. Despite what could be considered as only a small
difference in the sterics of the Gisoꢀ and Prisoꢀ ligands, the
former stabilises the indium(I) complex, 4 (mp 168–169 1C
decomp.), whereas the related complex, [In(Priso)], is appar-
ently unstable with respect to disproportionation, to form 12.
The fact that both indium(I) and (II) products were isolated
from the reaction involving Pipisoꢀ, which is of intermediate
steric bulk, adds weight to this proposal. Interestingly,
although PGisoꢀ appears to have a comparable ability to
stabilise indium(I) as does its apparently similarly bulky
counterpart, Gisoꢀ, it acts as an N,arene-ꢀchelating ligand in
15 as opposed to the N,N0-chelating Giso ligand in 4. This
could be due to the fact that the P-centre in PGisoꢀ can only
be pyramidal whereas the amino N-centre of Gisoꢀ is nor-
mally planar. This gives rise to both electronic and spatial
differences between the ligands.
The spectroscopic data for 12–15 largely reflect their solid
state structures which were all determined by X-ray crystal-
lographic studies. The molecular structures of 12–15 are
shown in Fig. 3–5. Two crystallographically independent
molecules were refined in the asymmetric unit of the structure
of 12. The geometries of both are similar and so only the
metrical parameters for one are included in the caption of
Fig. 3. As 15 is isomorphous with 11, its structure has been
Table 1 Selected bond lengths (A) and angles (1) for 9–11 and 15
9
10
11
15
N–M
N(1)–C(1)
N(2)–C(1)
2.429(2) 2.443(3) 2.417(3) 2.2829(19)
1.358(4) 1.354(4) 1.348(4) 1.360(3)
1.319(4) 1.313(5) 1.316(5) 1.305(3)
N(3)–C(1) or P(1)–C(1) 1.402(4) 1.410(4) 1.882(4) 1.885(2)
M–C(14)
2.903(3) 2.916(3) 2.884(4) 2.799(4)
N(1)–C(1)–N(2)
122.4(3) 123.2(3) 123.6(3) 123.52(18)
Scheme 2 Reagents: (i) InCl, toluene, –LiCl.
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Fig. 5 Molecular structure of 14 (25% thermal ellipsoids are shown;
hydrogen atoms omitted for sake of clarity). Selected bond lengths (A)
and angles (1): In(1)–N(1) 2.298(2), N(1)–C(1) 1.345(3), N(2)–C(1)
1.375(5); N(1)–In(1)–N(1)0 57.90(11), C(1)–N(1)–In(1) 95.24(17),
N(1)–C(1)–N(1)0 111.6(3). Symmetry operation: 0 ꢀx + 1, y, ꢀz + 3/2.
Fig. 3 Molecular structure of 12 (25% thermal ellipsoids are shown;
hydrogen atoms omitted for sake of clarity). Selected bond lengths (A)
and angles (1): In(1)–N(2) 2.177(10), In(1)–N(1) 2.194(9), In(1)–Cl(1)
2.392(3), In(1)–In(2) 2.7196(13), N(1)–C(1) 1.316(14), C(1)–N(2)
1.346(14), C(1)–N(3) 1.416(13), In(2)–N(5) 2.171(10), In(2)–N(4)
2.185(9), In(2)–Cl(2) 2.375(3), N(4)–C(32) 1.356(14), N(5)–C(32)
1.371(13), N(6)–C(32) 1.339(14); N(2)–In(1)–N(1) 61.3(3), N(2)–In(1)–
Cl(1) 113.3(3), N(1)–In(1)–Cl(1) 106.7(3), N(2)–In(1)–In(2) 121.9(3),
N(1)–In(1)–In(2) 129.9(3), Cl(1)–In(1)–In(2) 113.75(9), N(1)–C(1)–N(2)
113.5(10), N(5)–In(2)–N(4) 61.4(3), N(5)–In(2)–Cl(2) 108.8(3),
N(4)–In(2)–Cl(2) 113.6(3), N(5)–In(2)–In(1) 125.6(2), N(4)–In(2)–In(1)
118.8(3), Cl(2)–In(2)–In(1) 116.90(10), N(4)–C(32)–N(5) 109.3(9).
these products could be identified in the reaction with Li[PGiso].
The only products identified from the reactions with Li[Priso]
and Li[Pipiso] were the dimeric gallium(II) complexes, [{GaI(Pri-
so)}2] (yield o10%, colourless crystals, mp 124–128 1C decomp.)
and [{GaI(Pipiso)}2] (yield o10%, colourless crystals, mp
186–188 1C decomp.), which X-ray crystallographic studies
proved to be isostructural to 8, 12 and 13. However, the quality
of the structures proved too low for inclusion here. Moreover,
many attempts to crystallise these low yield products free of
impurities met with failure and as a result meaningful assign-
ments of their spectroscopic data could not be made. These
results do, however, show that the NCy2 backbone substituent of
Gisoꢀ gives that ligand a greater ability to stabilise gallium(I) (as
in 3, mp 158–159 1C11) than the other ligands used in this study.
Despite the greater stabilising ability of the Gisoꢀ ligand, the
1 : 1 reaction of its lithium salt with ‘‘GaI’’ gave only a 35%
yield of 3 and no other identifiable products.11 In an attempt to
increase the yield of this reaction, Li[Giso] was reacted with 4
equivalents of ‘‘GaI’’ in toluene. However, upon work-up
compound 3 was not found to be present in the reaction mixture
but instead a low yield (o5%) of the gallium(III) compound,
[GaI2(Giso)] 16, was formed. It seems likely that this reaction
proceeds via transfer of iodine from the excess ‘‘GaI’’ to the
gallium centre of initially formed [Ga(Giso)] 3, with concomitant
deposition of gallium metal. A rational synthesis of 16 was
devised whereby 3 was treated with one equivalent of diiodine
which oxidatively added to its gallium(I) centre to give 16 in low
yield (Scheme 3). In order to test the generality of oxidative
additions to 3, it was also treated with one equivalent of SiMe3I
which gave a good yield of 17.
fragment is delocalised with C–N distances (1.345(3) A) that are
only slightly shorter than the backbone C–N(amino) separation
of 1.375(5) A. Both the In–N distances of 14 are substantially
longer than those in 12 and 13, as would be expected considering
the lower indium oxidation state in the former.
The reactions of lithium salts of the three guanidinates used in
this study with ‘‘GaI’’ were carried out using toluene as a solvent.
In all cases the reactions led to many products as determined
1
from the H NMR spectra of the product mixtures. None of
Fig. 4 Molecular structure of 13 (25% thermal ellipsoids are shown;
hydrogen atoms omitted for sake of clarity). Selected bond lengths (A) and
angles (1): In(1)–N(1) 2.162(3), In(1)–N(2) 2.173(3), In(1)–Cl(1) 2.3752(12),
In(1)–In(1)0 2.7085(7), N(1)–C(1) 1.344(4), C(1)–N(2) 1.344(5), C(1)–N(3)
1.375(5); N(1)–In(1)–N(2) 61.17(12), N(1)–In(1)–Cl(1) 106.62(10),
N(2)–In(1)–Cl(1) 117.87(9), N(1)–In(1)–In(1)0 127.46(9), N(2)–In(1)–In(1)0
118.06(8), Cl(1)0 –In(1)–In(1)0 115.24(4), N(2)–C(1)–N(1) 110.3(3). Symme-
try operation: ꢀx + 1, ꢀy + 1, ꢀz + 1.
Scheme 3 Reagents: (i) I2, toluene; (ii) SiMe3I, toluene.
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argon or dinitrogen. Hexane and toluene were distilled over
molten potassium metal. Melting points were determined in
sealed glass capillaries under argon and are uncorrected. Mass
spectra were recorded at the EPSRC National Mass Spectro-
metric Service at Swansea University. Microanalyses were
obtained from Medac Ltd. IR spectra were recorded using a
Nicolet 510 FT-IR spectrometer as Nujol mulls between NaCl
plates. 1H and 13C{1H} NMR spectra were recorded on a
Bruker DXP400 spectrometer and were referenced to the
resonances of the solvent used. 31P{1H} NMR spectra were
recorded on a Jeol Eclipse 300 spectrometer and were refer-
enced to external 85% H3PO4. Reproducible microanalyses
could not be obtained for several complexes because of their
1
very air and moisture sensitive nature. The H NMR spectra
for all such complexes indicate that they have bulk purities of
495%. Li[Priso],15b Li[Pipiso]20 and [Ga(Giso)]11 were
synthesised by variations of literature procedures. PGisoH
was prepared by an equivalent procedure to that used to
prepare GisoH.11 All other reagents were used as received.
Preparation of [Tl(N,arene-Priso)] 9
Fig. 6 Molecular structure of 16 (25% thermal ellipsoids are shown;
hydrogen atoms omitted for sake of clarity). Selected bond lengths (A)
and angles (1): I(1)–Ga(1) 2.5090(9), Ga(1)–N(1) 1.953(5), N(1)–C(1)
1.372(7); N(1)–Ga(1)–N(1)0 68.6(3), N(1)–Ga(1)–I(1)0 123.83(15),
N(1)–Ga(1)–I(1) 115.54(15), I(1)0–Ga(1)–I(1) 106.57(6), N(2)–C(1)–N(1)0
TlBr (0.94 g, 3.32 mmol) was added to a cooled slurry of
Li[Priso] (1.36 g, 2.89 mmol) in toluene (30 cm3) at ꢀ80 1C.
The mixture was warmed to ambient temperature overnight
with stirring. It was then filtered and volatiles removed from
the filtrate under reduced pressure. The residue was extracted
with hexane (40 cm3), concentrated to ca. 12 cm3 and slow
cooled to ꢀ30 1C to afford yellow crystals of 9 (yield 1.08 g,
0
126.7(3). Symmetry operation: ꢀx + 3/2, ꢀy + 1/2, z.
Both compounds were spectroscopically characterised and the
X-ray crystal structure of 16 obtained (Fig. 6). This shows the
complex to be monomeric with a distorted tetrahedral gallium
coordination geometry and Ga–I distances in the known range.18
The geometry of the delocalised Gisoꢀ ligand in 16 is very similar
to that in 3, but its Ga–N bond lengths are substantially shorter,
as would be expected for a gallium(III) compound.
1
56%); mp 170–172 1C (ca. 190 1C decomp.). H NMR (400
MHz, C6D6, 298 K): d 1.30 (d, very broad, 12 H, CH(CH3)2),
1.44 (broad d, 3JHH = 6.8 Hz, 12 H, CH(CH3)2), 1.46 (broad
3
d, JHH = 6.8 Hz, 12 H, CH(CH3)2), 3.65–3.77 (m of over-
3
lapping sept, JHH = 6.8 Hz, 6 H, CH(CH3)2), 6.96–7.04 (m,
very broad, 2 H, ArH), 7.22–7.33 (m, 4 H, ArH); 13C{1H}
NMR (100.6 MHz, C6D6, 298 K): d 23.1 (NCH(CH3)2), 22.7
(very broad, ArCH(CH3)2), 28.3 (very broad, ArCH(CH3)2),
49.0 (NCH(CH3)2), 122.5 (very broad, ArC), 125.2 (very
broad, ArC), 143.3 (very broad, ArC), 164 (very broad, back-
bone CN3); no other ArC resonances were observed; IR n/
cmꢀ1 (Nujol): 1612 (s), 1582 (m), 1256 (m), 1149 (m), 1045 (m),
952 (m), 851 (m), 756 (s); MS (EI 70 eV), m/z (%): 668.4
(M + H+, 1), 464.5 (PrisoH, 100); accurate MS (EI) calc. for
C31H48N3205Tl: 668.3665, found: 668.3691.
Conclusion
In summary, the reactions of two bulky guanidinates (Prisoꢀ
and Pipisoꢀ) and one phosphaguanidinate (PGisoꢀ) towards a
series of group 13 metal(I) halides have been carried out. The
outcomes of these reactions have been compared to those
involving a related guanidinate (Gisoꢀ). The study shows that
subtle changes to the sterics and electronics of the backbone
substituent (ꢀER2) of the general unit, [ArNC(ER2)NAr]ꢀ
(E = N or P), can have a marked effect on the stability, metal
oxidation state and ligand coordination mode of the product
obtained. The Gisoꢀ ligand is the most adept at stabilising
group 13 metal(I) complexes, and complexes in which the
metal centre is N,N0-chelated. Studies continue in our labora-
tory on the use of bulky guanidinates to prepare stable
complexes containing low oxidation state metal centres from
across the periodic table.
Preparation of [Tl(N,arene-Pipiso)] 10
TlBr (0.78 g, 2.74 mmol) was added to a cooled slurry of
Li[Pipiso] (1.10 g, 2.28 mmol) in toluene (30 cm3) at ꢀ80 1C.
The mixture was warmed to ambient temperature overnight
with stirring. It was then filtered and volatiles removed under
reduced pressure. The residue was extracted with hexane (20
cm3), concentrated to ca. 5 cm3 and slow cooled to ꢀ30 1C to
afford yellow crystals of 10 (yield 0.98 g, 63%); mp 144–146 1C
1
(ca. 170 1C decomp.). H NMR (400 MHz, C6D6, 298 K): d
Experimental section
1.24–1.53 (m, very broad, 22 H, CH(CH3)2, NCHCH3, CH2),
1.55 (d, 3JHH = 6.8 Hz, 12 H, CH(CH3)2), 1.73–1.90 (m, very
broad, 2 H, CH2), 3.73 (mc, 4 H, CH(CH3)2), 4.14 (mc, 2 H,
NCHCH3), 6.93–7.11 (m, very broad, 2 H, ArH), 7.24–7.35
(m, 4 H, ArH); 13C{1H} NMR (100.6 MHz, C6D6, 298 K):
General considerations
All manipulations were carried out using standard Schlenk
and glove box techniques under atmospheres of high purity
ꢂc
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d 15.4 (CH2), 21.8 (CH3), 23.4 (broad, CH(CH3)2), 28.3
(broad, CH(CH3)2), 30.9 (CH2), 49.0 (NCHCH3), 122.8 (very
broad), 124.3 (very broad), 141.0 (very broad), 144.3 (very
broad) (ArC), 164.8 (very broad, backbone CN3); IR n/cmꢀ1
(Nujol): 1615 (m), 1584 (m), 1227 (m), 1193 (m), 1143 (m),
1118 (m), 1018 (m), 907 (m), 770 (m), 757 (m); MS (EI 70 eV),
Preparation of [{InCl(N,N0-Pipiso)}2] 13 and [In(N,N0-Pipiso)]
14
InCl (0.33 g, 2.20 mmol) was added to a slurry of Li[Pipiso]
(0.92 g, 1.91 mmol) in toluene (30 cm3) at ꢀ80 1C. The mixture
was warmed to ambient temperature and stirred over night. It
was then filtered and all volatiles were removed under reduced
pressure. The residue was extracted into hexane (50 cm3),
concentrated to ca. 30 cm3 and slowly cooled to ꢀ30 1C to
give colourless crystals of 13. The supernatant was further
concentrated to ca. 5 cm3 to give colourless crystals of 14.
Data for 13: (yield 0.26 g, 22%), mp 172–173 1C (decomp.); 1H
NMR (400 MHz, C6D6, 298 K): d 0.75 (d, 3JHH = 6.6 Hz, 12
H, NCHCH3), 1.25–1.73 (m, 36 H, CH(CH3)2, CH2), 1.47 (d,
3JHH = 6.8 Hz, 24 H, CH(CH3)2), 3.97 (mc, 12 H, CH(CH3)2,
NCHCH3), 7.05–7.27 (m, 12 H, ArH); 13C{1H} NMR (100.6
MHz, C6D6, 298 K): d 13.1 (CH2), 20.9 (CH3), 23.0 (CH(-
CH3)2), 27.5 (CH(CH3)2), 28.0 (CH(CH3)2), 29.3 (CH2), 48.4
(NCHCH3), 122.3, 123.7, 125.5, 140.3, 142.6, 144.7 (ArC),
164.3 (backbone CN3); IR n/cmꢀ1 (Nujol): 1616 (m), 1584 (m),
1113 (m), 1076 (m), 1021 (m), 931 (m), 798 (s), 754 (m); MS (EI
70 eV), m/z (%): 589.3 (M+, 1), 546.2 (M+ ꢀ Pri, 2), 432.3
(PipisoH ꢀ Pri, 100).
i
m/z (%): 679.1 (M+, 1), 636.1 (M+ ꢀ Pr, 3), 432.3 (PipisoH ꢀ
Pri, 100); accurate MS (EI) calc. for C32H49N3Tl1 (MH+):
679.3587 found: 679.3580.
Preparation of [Tl(N,arene-PGiso)] 11
BunLi (0.65 cm3 of a 1.6 m solution in hexanes, 1.04 mmol)
was added to a solution of PGisoH (0.57 g, 1.02 mmol) in
toluene (20 cm3) at 20 1C and the resultant solution stirred for
1 h. Solid TlBr (0.35 g, 1.22 mmol) was then added to the
solution at ꢀ80 1C. The mixture was slowly warmed to
ambient temperature and stirred overnight. All volatiles were
removed under reduced pressure, the residue extracted into
hexane (60 cm3) and filtered. The filtrate was concentrated to
ca. 15 cm3 and stored at ꢀ30 1C to give light yellow crystals of
1
11 (yield 0.18 g, 23%); mp 70 1C (decomp.). H NMR (400
3
MHz, C6D6, 298 K): d 1.20 (d, JHH = 6.7 Hz, 6 H, CH(C-
H3)2), 1.34 (d, 3JHH = 6.7 Hz, 6 H, CH(CH3)2), 1.41 (d, 3JHH
Data for 14: (yield 0.20 g, 18%); mp 119–121 1C (decomp.);
1H NMR (400 MHz, C6D6, 298 K): d 0.83 (d, 3JHH = 6.6 Hz,
6 H, NCHCH3), 0.90–1.56 (m, 6 H, CH2), 1.44 (d, 3JHH = 6.8
3
= 6.7 Hz, 6 H, CH(CH3)2), 1.61 (d, JHH = 6.7 Hz, 6 H,
CH(CH3)2), 1.36–2.28 (m, 20 H, CH2), 2.40 (m, 2 H, CHP),
3
3
3
Hz, 12 H, CH(CH3)2), 1.48 (d, JHH = 6.8 Hz, 12 H,
3
3.58 (sept, JHH = 6.7 Hz, 2 H, CH(CH3)2), 3.65 (sept, JHH
= 6.7 Hz, 2 H, CH(CH3)2), 6.90–7.45 (m, 6 H, ArH); 31P
NMR (121 MHz, C6D6, 298 K): d 3.3; 13C{1H} NMR (100.6
MHz, C6D6, 298 K): d 23.0, 23.5, 25.4, 28.5 (CH(CH3)2), 27.2,
CH(CH3)2), 3.77 (sept, JHH = 6.8 Hz, 4 H, CH(CH3)2),
3.96 (mc, 2 H, NCHCH3), 7.13–7.29 (m, 6 H, ArH); 13C{1H}
NMR (100.6 MHz, C6D6, 298 K): d 12.6 (CH2), 19.7 (CH3),
20.7 (CH(CH3)2), 26.6 (CH(CH3)2), 26.7 (CH(CH3)2), 28.9
(CH2), 46.1 (NCHCH3), 122.0, 141.3, 142.9 (one ArC reso-
nance not observed), 164.8 (backbone CN3); IR n/cmꢀ1 (Nu-
jol): 1616 (m), 1585 (m), 1260 (m), 1110 (m), 1076 (m), 1024
(m), 932 (m), 796 (s), 756 (m); MS (EI 70 eV), m/z (%): 589.3
(M+, 1), 546.2 (M+ ꢀ Pri, 2), 432.3 (PipisoH ꢀ Pri, 100);
accurate MS (EI) calc. for C32H49N3In1 (MH+): 589.2882,
found: 589.2877.
2
28.1, 28.2, 29.4, 33.1 (d, JCP = 17.1 Hz) (CH2), 27.4, 28.3
1
(CH(CH3)2), 34.7 (d, JCP = 22.4 Hz, CHP), 123.4, 123.6,
124.3, 127.4, 138.3, 139.2, 144.0, 155.9 (ArC), 170.0 (br,
backbone CN2); MS (EI 70 eV), m/z (%): 764.4 (M+, 5),
721.4 (M+ ꢀ Pri, 15), 477.3 (M+ ꢀ Cy2P, 35); IR n/cmꢀ1
(Nujol): 1566 (m), 1336 (m), 1313 (m), 1257 (m), 1178 (m), 914
(m); accurate MS (EI) calc. for C37H56N2P203Tl: 761.3821
(M ꢀ H+), found 761.3830; C37H55N2PTl requires C 58.15,
H 7.39, N 3.66%; found C 58.07, H 7.14, N 3.64%.
Preparation of [In(N,arene-PGiso)] 15
Preparation of [{InCl(N,N0-Priso)}2] 12
BunLi (0.82 cm3 of a 1.6 m solution in hexanes, 1.30 mmol)
was added to a solution of Cy2PGisoH (0.72 g, 1.28 mmol) in
toluene (20 cm3) at room temperature, and stirred for 1 h.
Solid InCl (0.23 g, 1.54 mmol) was then added to the above
solution at ꢀ80 1C. The mixture was slowly warmed to room
temperature and stirred overnight. All volatiles were removed
under reduced pressure, the residue extracted into hexane (60
cm3) and filtered. The filtrate was concentrated to ca. 15 cm3
and stored at ꢀ30 1C to give colourless blocks of 15 (yield 0.25
g, 29%); mp 84 1C (decomp.); 1H NMR (400 MHz, C6D6, 298
InCl (0.30 g, 2.00 mmol) was added to a slurry of Li[Priso]
(0.80 g, 1.70 mmol) in toluene (25 cm3) at ꢀ80 1C. The mixture
was warmed to room temperature and stirred overnight. It was
then filtered and all volatiles were removed under reduced
pressure. The residue was extracted into hexane (50 cm3),
concentrated to ca. 20 cm3 and slow cooled to ꢀ30 1C to give
colourless crystals of 12 (yield 0.33 g, 32%); mp 178–180 1C
(decomp.); 1H NMR (400 MHz, C6D6, 298 K): d 0.91 (d, 3JHH
= 6.8 Hz, 24 H, NCH(CH3)2), 1.42 (d, 3JHH = 6.8 Hz, 24 H,
CH(CH3)2), 1.28–1.86 (m, very broad, 24 H, CH(CH3)2),
3.90–4.12 (m of overlapping sept, 12 H, CH(CH3)2),
7.03–7.28 (m, 12 H, ArH); 13C{1H} NMR (100.6 MHz,
C6D6, 298 K): d 22.0 (ArCH(CH3)2), 22.4 (NCH(CH3)2),
26.4 (ArCH(CH3)2), 26.7 (ArCH(CH3)2), 49.2 (NCH(CH3)2),
122.5, 124.3, 139.2, 143.6 (very broad, ArC), 164.9 (backbone
CN3); IR n/cmꢀ1 (Nujol): 1611 (s), 1581 (m), 1257 (m), 1154
(m), 1109 (s), 1047 (m), 799 (s), 751 (m); MS (CI), m/z (%):
462.5 (Prisoꢀ ꢀ H, 100).
3
3
K): d 1.21 (d, JHH = 6.8 Hz, 6 H, CH(CH3)2), 1.37 (d, JHH
= 6.8 Hz, 6 H, CH(CH3)2), 1.38 (d, JHH = 6.8 Hz, 6 H,
3
3
CH(CH3)2), 1.57 (d, JHH = 6.8 Hz, 6 H, CH(CH3)2),
1.35–2.21 (m, 20 H, CH2), 2.37 (m, 2 H, CHP), 3.46 (sept,
3JHH = 6.8 Hz, 2 H, CH(CH3)2), 3.56 (sept, 3JHH = 6.8 Hz, 2
H, CH(CH3)2), 6.91–7.49 (m, 6 H, ArH); 31P NMR (121.6
MHz, C6D6, 298 K): d 0.1; 13C{1H} NMR (100.6 MHz, C6D6,
298 K): d 22.8, 23.5, 25.1, 28.2 (CH(CH3)2), 27.8, 28.4
2
(CH(CH3)2), 27.2, 28.1, 28.6, 29.1, 33.0 (d, JCP = 16.1 Hz)
ꢂc
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Table 2 Crystal data for compounds 9–16
Compound
9
10
11
12
13
14
15
16
Empirical formula
Mr
T/K
Crystal system
Space group
a/A
b/A
c/A
C31H48N3Tl C32H48N3Tl
C37H56N2PTl C62H96Cl2In2N6 C64H96Cl2In2N6 C32H48InN3
C37H56InN2P C37H56GaI2N3
667.09
150(2)
Monoclinic
P21/c
679.10
150(2)
Monoclinic
P21/c
764.18
150(2)
Triclinic
1225.99
150(2)
Triclinic
1250.01
150(2)
Monoclinic
P21/n
589.55
150(2)
Monoclinic
C2/c
674.63
150(2)
Triclinic
P-1
866.37
150(2)
Tetragonal
P42/n
ꢀ
ꢀ
P1
P1
14.425(3)
11.625(2)
18.247(4)
90
17.940(4)
17.922(4)
20.153(4)
90
9.844(5)
12.034(5)
16.117(5)
82.340(5)
79.940(5)
68.729(5)
1746.7(13)
2
1.453
4.696
776
14 179
14.424(3)
22.313(5)
22.538(5)
116.69(3)
97.26(3)
96.81(3)
6301(2)
4
1.292
0.857
2568
40 299
21 836
0.0721
11.518(2)
19.205(4)
14.668(3)
90
103.02(3)
90
3161.0(11)
2
1.313
0.856
1308
17.298(4)
11.948(2)
15.609(3)
90
102.04(3)
90
3155.0(11)
4
1.241
0.772
1240
9.866(5)
12.021(5)
16.135(5)
82.804(5)
80.474(5)
68.833(5)
1755.4(13)
2
12.5767(18)
12.5767(18)
23.270(5)
90
90
90
3680.7(11)
4
1.563
2.454
1744
a/1
b/1
104.28(3)
90
107.01(3)
90
g/1
V/A3
2965.1(10)
4
1.494
6196(2)
8
1.456
Z
Dc/Mg mꢀ3
m(Mo-Ka)/mmꢀ1
F(000)
1.276
0.745
712
5.470
1344
5.236
2736
No. reflections collected 11 705
No. independent reflns 6130
Rint
Final R1 (I 4 2s(I))
and wR2 indices
(all data)
37 199
13 411
0.0542
22 412
6459
6276
3340
0.0262
14 452
7622
0.0282
5324
3241
0.0450
7564
0.0401
0.0302
0.0631
R1 = 0.0455
wR2 = 0.0575 wR2 = 0.0725 wR2 = 0.0748 wR2 = 0.2388 wR2 = 0.1193 wR2 = 0.1098 wR2 = 0.0807 wR2 = 0.1216
R1 = 0.0269 R1 = 0.0369 R1 = 0.0371 R1 = 0.1049
R1 = 0.0394 R1 = 0.0326 R1 = 0.0670
1
(CH2), 34.3 (d, JCP = 23.1 Hz, CHP); 123.3, 125.3, 128.3,
affording 17 as a microcrystalline off-white solid (yield 90 mg,
62%); mp 175–177 1C (decomp.); 1H NMR (400 MHz, 296 K,
C6D6): d 0.51 (s, 9 H, Si(CH3)3), 0.73–0.88 (m, broad, 6 H,
CH2), 1.31 (d, 3JHH = 6.8 Hz, 6 H, CH(CH3)2), 1.40–1.90 (m,
14 H, CH2), 1.45 (d, 3JHH = 6.8 Hz, 6 H, CH(CH3)2), 1.60 (d,
3JHH = 6.8 Hz, 6 H, CH(CH3)2), 1.63 (d, 3JHH = 6.8 Hz, 6 H,
CH(CH3)2), 3.56 (mc, 2 H, NCH), 3.80 (sept, 3JHH = 6.8 Hz, 2
1
128.7, 138.7, 139.9, 140.0, 145.2 (ArC), 169.5 (d, JCP = 21.2
Hz, backbone CN2); MS (EI 70 eV), m/z (%): 674 (M+, 12),
631 (M+ ꢀ Pri, 33), 477.3 (M+ ꢀ Cy2P, 84); IR n/cmꢀ1
(Nujol): 1565 (m), 1429 (m), 1329 (m), 1286 (m), 1178 (m),
1152 (m), 918 (m), 757 (m); accurate MS (EI) calc. for calc. for
C37H55N2InP (M
ꢀ
H+): 673.3136, found 673.3144;
3
C37H56N2InP requires C 65.87, H 8.37, N 4.15%; found C
65.61, H 8.45, N 4.29%.
H, CH(CH3)2), 4.27 (sept, JHH = 6.8 Hz, 2 H, CH(CH3)2),
7.14–7.30 (m, 6 H, ArH); 13C{1H} NMR (100.6 MHz, C6D6,
298 K): d 0.2 (Si(CH3)3), 21.6 (CH(CH3)2), 22.4 (CH2), 24.4
(CH2), 25.9 (CH(CH3)2), 27.1 (CH(CH3)2), 27.4 (CH(CH3)2),
27.6 (CH(CH3)2), 30.8 (CH(CH3)2), 33.5 (CH2), 58.3 (NCH),
122.4, 124.0, 124.9, 138.8, 143.3, 145.2 (ArC), 164.6 (backbone
CN3); IR n/cmꢀ1 (Nujol): 1611 (m), 1583 (m), 1259 (m), 1176
(m), 1095 (m), 1021 (m), 896 (m), 838 (s), 800 (s), 772 (m), 688
(m); MS (EI 70 eV), m/z (%): 812.3 (M+ + H, 1), 796.2
(M+ ꢀ Me, 3), 738.3 (M+ ꢀ SiMe3, 1), 684.4 (M+ ꢀ I, 47),
528.3 (GisoH+ ꢀ Me, 100); accurate MS (EI) calc. for calc. for
C40H64GaN3ISi (M+ ꢀ H): 810.3165, found: 810.3159.
Preparation of [GaI2(Giso)] 16
I2 (17 mg, 0.07 mmol) was added to a solution of [Ga(Giso)]
(40 mg, 0.07 mmol) in toluene (5 cm3) at ꢀ80 1C. The solution
was slowly warmed to room temperature overnight with
stirring. All volatiles were then removed under reduced pres-
sure and the residue extracted into hexane (10 cm3) and
filtered. The filtrate was slowly cooled to ꢀ30 1C affording
16 as a colourless crystalline solid (yield 16 mg, 26%); mp
1
203–205 1C; H NMR (400 MHz, 296 K, C6D6) d 0.82–1.23
(m, 8 H, CH2), 1.32 (d, 3JHH = 6.8 Hz, 12 H, CH(CH3)2), 1.45
X-Ray crystallography
3
(d, JHH = 6.8 Hz, 12 H, CH(CH3)2), 1.41–1.73 (m, 12 H,
3
Crystals of 9–16 suitable for X-ray structural determination
were mounted in silicone oil. Crystallographic measurements
were made using a Nonius Kappa CCD diffractometer. The
structures were solved by direct methods and refined on F2 by
full matrix least squares (SHELX97)21 using all unique data.
Hydrogen atoms have been included in calculated positions
(riding model) for all structures. Crystal data, details of data
collections and refinement are given in Table 2.
CH2), 3.43 (m, 2 H, CHN), 3.81 (sept, JHH = 6.8 Hz, 4 H,
CH(CH3)2), 7.04–7.42 (m, 6 H, ArH); 13C NMR (100.6 MHz,
C6D6) d 21.5 (CH2), 23.3 (CH(CH3)2), 225.8 (CH(CH3)2), 28.3
(CH(CH3)2), 32.7 (CH2), 34.0 (CH2), 58.1 (HCN), 123.1,
124.5, 145.3, 145.8 (ArC), 165.7 (CN3); IR n/cmꢀ1 (Nujol):
1608 (s), 1583 (m), 1258 (m), 1018 (m); MS (EI 70 eV) m/z (%):
866.3 (M+, 3%), 500.3 (GisoH+ ꢀ Pri, 100%).
Preparation of [GaI(SiMe3)(Giso)] 17
Me3SiI (40 mL, 56 mg, 0.28 mmol) was added to a solution of
[Ga(Giso)] (0.11 g, 0.18 mmol) in toluene (8 cm3) at ꢀ80 1C.
The solution was slowly warmed to room temperature over-
night with stirring. All volatiles were then removed under
reduced pressure and the residue extracted into hexane (10
cm3) and filtered. The filtrate was slowly cooled to ꢀ30 1C
Acknowledgements
We thank the Australian Research Council (fellowships for
C. J. and A. S.) and the Royal Society (fellowship for G. J.) for
financial support. The EPSRC Mass Spectrometry Service at
Swansea University is also thanked.
ꢂc
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A. Schier and H. Schmidbaur, J. Chem. Soc., Dalton Trans., 2001,
505.
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18 As determined from a survey of the Cambridge Crystallographic
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a
related anion, [:Ga{[N(But)C(H)]2}]ꢀ, had been
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H. Schmidbaur, J. Am. Chem. Soc., 1999, 121, 9758; E. S. Schmidt,
21 G. M. Sheldrick, SHELX-97, University of Gottingen, 1997.
¨
ꢂc
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842 | New J. Chem., 2008, 32, 835–842