Stabilisation of an inorganic digallane by the phosphinobisthiolato P,S,S pincer ligand PPh(2-SC6H4)2

Article abstract of DOI:10.1039/b907668a

The pincer ligand PPh(2-HSC₆H₄)₂ reacts with GaCl₃ in the presence of triethylamine to yield the anionic gallium complex [NEt₃H][Ga{PPh(2-SC₆H₄) ₂-κ³S,S′,P}

Full text of DOI:10.1039/b907668a

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Stabilisation of an inorganic digallane by the phosphinobisthiolato
P,S,S pincer ligand PPh(2-SC6H4)2w
ab
b
b
˘
´
¨
Ana-Maria Valean, Santiago Gomez-Ruiz, Peter Lonnecke,
Ioan Silaghi-Dumitrescu,a Luminita Silaghi-Dumitrescu*a
and Evamarie Hey-Hawkins*b
Received (in Victoria, Australia) 16th April 2009, Accepted 2nd June 2009
First published as an Advance Article on the web 8th July 2009
DOI: 10.1039/b907668a
The pincer ligand PPh(2-HSC6H4)2 reacts with GaCl3 in the presence of triethylamine to yield the
anionic gallium complex [NEt3H][Ga{PPh(2-SC6H4)2-k3S,S0,P}{PPh(2-SC6H4)2-k2S,S0}] (1),
which undergoes cation exchange with PPh4Cl to give [PPh4][Ga{PPh(2-SC6H4)2-
k3S,S0,P}{PPh(2-SC6H4)2-k2S,S0}] (2). Neutral complexes GaR{PPh(2-SC6H4)2-k3S,S0,P}
t
[R = Me (3), Bu (4)] were obtained by reaction of PPh(2-HSC6H4)2 with trialkyl gallium
compounds (GaMe3, GatBu3). Compound 4 is light-sensitive and decomposes in daylight
or under UV irradiation. Three decomposition products could be isolated: tetranuclear
hydrido-bridged mixed-valent gallium(II)–gallium(III) complex [GaIII{PPh(2-SC6H4)-k2S,P-m-
(2-SC6H4)-kS0}2]2(m3-H)2GaII (Ga–Ga) (5), gallium(II) complex [Ga{PPh(2-SC6H4)2-k3S,S0,P}]2
2
(Ga–Ga) (6), and sulfido-bridged dinuclear complex [Ga{PPh(2-SC6H4)2-k3S,S0,P}]2(m-S) (7). The
molecular structures of 2–7 are described.
t
neutral [GaR{PPh(2-SC6H4)2-k3S,S0,P}; R = Me (3), Bu (4)]
gallium(III) complexes. The tBu derivative 4 is light-sensitive and
decomposed with the formation of a new dimeric dithiolato
gallium(II) compound with a Ga–Ga single bond, namely,
[Ga{PPh(2-SC6H4)2-k3S,S0,P}]2 (Ga–Ga) (6), along with
unusual mixed-valent gallium(II)–gallium(III) hydride complex
Introduction
There is considerable current interest in polydentate hetero-
donor ligands involving tertiary phosphine groups in
combination with nitrogen, oxygen or sulfur donors. Of these,
phosphinothiolates derived from thiophenol [PPh2(2-HSC6H4)
(PSH), PPh(2-HSC6H4)2 (PS2H2) and P(2-HSC6H4)3 (PS3H3)]
have been shown to be highly versatile ligands that form stable
complexes with a wide range of elements, especially compounds
of the heavier transition metals.1,2
[GaIII{PPh(2-SC6H4)-k2S,P-m-(2-SC6H4)-kS0}2]2(m3-H)2GaII
(Ga–Ga) (5), and sulfido complex [Ga{PPh(2-SC6H4)2-
k3S,S0,P}]2(m-S) (7).
2
In particular, the PS2H2 ligand is interesting due to the wide
range of potential coordination patterns which result from
combinations of phosphorus and sulfur coordination: as P,S,S
pincer ligands, as bidentate P,S or S,S ligands, as monodentate
S or P ligands, and, additionally, as doubly or triply bridging
ligands. Although the chemistry of the PS2H2 ligand with
transition metals has been studied to some extent,1a,2 only a
few complexes of main group metals have been reported so
far.3 Until now there have been no reported examples of
gallium complexes with this type of ligand.
Results and discussion
Gallium(III) chloride reacts with PPh(2-HSC6H4)2 (PS2H2) in
the presence of triethylamine with the formation of the anionic
gallium complex [NEt3H][Ga{PPh(2-SC6H4)2-k3S,S0,P}-
{PPh(2-SC6H4)2-k2S,S0}] (1). Cation exchange with PPh4Cl
gave the crystalline compound [PPh4][Ga{PPh(2-SC6H4)2-
k3S,S0,P}{PPh(2-SC6H4)2-k2S,S0}] (2). Neutral complexes
GaR{PPh(2-SC6H4)2-k3S,S0,P} [R = Me (3), Bu (4)] were
t
obtained by the reaction of PPh(2-HSC6H4)2 with trialkyl
gallium compounds (GaMe3, GatBu3; Scheme 1). Compounds
1–4 were obtained in good yield and were characterised by 1H,
31P{1H} NMR and IR spectroscopy, mass spectrometry and
X-ray crystallography. Complexes 1–3 are stable in solution
and in the solid state, whereas 4 decomposes in solution in
daylight. The decomposition leads to a mixture of gallium
compounds, of which three could be isolated and structurally
characterised (vide infra).
We now report the reaction of the potentially tridentate
PS2H2 ligand with gallium(III) chloride and trialkyl gallium
compounds (GaMe3, GatBu3), which resulted in anionic
([Ga{PPh(2-SC6H4)2-k3S,S0,P}{PPh(2-SC6H4)2-k2S,S0}]ꢀ) and
a Faculty of Chemistry and Chemical Engineering, ‘‘Babes-Bolyai’’
University, M. Koga˘lniceanu 1, 400082, Cluj-Napoca, Romania.
E-mail: lusi@chem.ubbcluj.ro; Fax: +40-264-590818;
Tel: +40-264-593833
b Institute of Inorganic Chemistry, Universitat Leipzig, Johannisallee
¨
Anionic complexes, [X][Ga{PPh(2-SC6H4)2-j3S,S0,P}-
{PPh(2-SC6H4)2-j2S,S0}] [X = NEt3H (1), PPh4 (2)]
29, 04103, Leipzig, Germany. E-mail: hey@rz.uni-leipzig.de;
Fax: +49-341-9739319; Tel: +49-341-9736151
w Electronic supplementary information (ESI) available: A comparison
between the experimental and theoretical UV-Vis spectroscopic data.
CCDC 722486 (2), 722487 (3), 722488 (4), 722489 (6) and 722490 (7).
For ESI and crystallographic data in CIF or other electronic format see
DOI: 10.1039/b907668a
The 1 : 1 or 2 : 1 reaction of PS2H2 with GaCl3 in methanol in the
presence of triethylamine resulted in the formation of [NEt3H]-
[Ga{PPh(2-SC6H4)2-k3S,S0,P}{PPh(2-SC6H4)2-k2S,S0}]
(1),
ꢁc
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Scheme 1
obtained as a white solid in good yield (84%; Scheme 1). The
absence of a nS–H band in the IR spectrum and the lack of
signals associated with the S–H group in the 1H NMR spectrum
confirmed the deprotonation of all thiol groups. The presence
of a HNEt3 cation was indicated in the IR [2675 cmꢀ1
(w, nN–H)] and 1H NMR spectra. The two sets of signals at
ꢀ23.9 and ꢀ26.3 (br) ppm in the 31P{1H} NMR spectrum are
related to the two non-equivalent phosphorus atoms, as in the
product obtained by cation exchange (compound 2) described
below. The gallium complex anion ([Mꢀ ꢀ NEt3H]) peak of
compound 1 was observed in the ESI MS (negative) spectrum
at m/z 716.96 with the appropriate isotopic distribution.
Low-quality crystals were obtained from CH3CN at room
temperature over a few weeks but were unsuitable for X-ray
structure determination.
Fig.
1
Molecular
structure
of
[PPh4][Ga{PPh(2-SC6H4)2-
k3S,S0,P}{PPh(2-SC6H4)2-k2S,S0}] (2) with thermal ellipsoids at 50%
probability. Hydrogen atoms and the diglyme molecule (solvent) are
omitted for clarity.
Cation exchange of 1 with one equivalent of PPh4Cl in
methanol at room temperature gave the crystalline phosphonium
salt [PPh4][Ga{PPh(2-SC6H4)2-k3S,S0,P}{PPh(2-SC6H4)2-k2S,S0}]
(2; Scheme 1). IR and NMR spectra confirm the proposed
formula. The 31P{1H} NMR spectrum shows the signal of the
PPh4 cation (22.9 ppm) and two singlets in the same range as
those of 1, at ꢀ23.9 and ꢀ29.3 (br) ppm.
Table 1 Selected bonds lengths (A) and angles (1) in 2
S1–Ga1
S2–Ga1
S3–Ga1
S4–Ga1
P2–Ga1
2.2970(9)
2.3784(8)
2.392(1)
2.310(1)
2.6992(9)
S1–Ga1–S4
S1–Ga1–S2
S4–Ga1–S2
S1–Ga1–S3
S4–Ga1–S3
S2–Ga1–S3
S1–Ga1–P2
S4–Ga1–P2
S2–Ga1–P2
S3–Ga1–P2
128.65(3)
104.10(4)
107.25(3)
111.41(2)
109.70(3)
87.32(2)
83.55(3)
78.79(3)
162.15(2)
74.85(2)
Crystals of 2 suitable for X-ray diffraction were obtained
from a saturated diglyme solution at room temperature.
ꢀ
Compound 2 crystallises in triclinic space group P1 with two
molecules in the unit cell, which also contains two diglyme
molecules, and consists of discrete cations and anions (Fig. 1).
The gallium atom is coordinated by one phosphorus and four
sulfur atoms in a distorted trigonal-bipyramidal geometry.
The atoms P2 and S2 occupy the axial position (P2–Ga1–S2
162.15(2)1; Table 1); the three equatorial sulfur atoms are
nearly coplanar with Ga1 [deviations: Ga1 0.321, S1 ꢀ0.118,
S3 ꢀ0.115 and S4 ꢀ0.089 A]. The Ga–S bond lengths (range
[NEt4][Ga(SPh)4] (2.242(3)–2.260(3) A), [NnPr4][Ga(SEt)4]
(2.264(1) A),5 [NiPr2H2][Ga(SiPr)4] (2.2541(6)–2.2796(6) A),6
and in the five-coordinate compound GaCl{(SC6H4-2-PPh2)-
k2S,P}2 (2.270(1)–2.295(1) A).7 The Ga1–P2 bond length
(2.6992(9) A) greatly exceeds that observed in GaCl{(SC6H4-
2-PPh2)-k2S,P}2 (Ga–P 2.4927(9) and 2.5872(1) A). The other
phosphorus atom is not coordinated to the gallium atom;
however, the Ga1ꢂ ꢂ ꢂP1 distance (2.975 A) is shorter than the
sum of the van der Waals radii (3.67 A),8 which could be
2.2970(9)–2.392(1)
A)
and
S–Ga–S
bond
angles
(87.32(2)–128.65(3)1) agree well with those of similar compounds
(Ga–S 2.205–2.446 A and S–Ga–S 81.80–123.731).4,5 Shorter
Ga–S bonds were observed in tetrakis-thiolato gallates
ꢁc
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indicative of some degree of Gaꢂ ꢂ ꢂP interaction. The reason
for the non-coordinating P1 atom could be steric hindrance
owing to the constraints of the chelate rings and the sterically
demanding phosphine groups.
Neutral complexes, GaR{PPh(2-SC6H4)2-j3S,S0,P} [R = Me
(3), Bu (4)]
t
The organogallium complexes GaR{PPh(2-SC6H4)2-k3S,S0,P}
t
[R = Me (3), Bu (4)] were obtained from the 1 : 1 or 2 : 1
reaction of PS2H2 with GaR3 (Scheme 1). The IR, 1H and
31P{1H} NMR spectra of 3 and 4 indicate P,S,S coordination
of the deprotonated ligand. The signals in the 31P{1H} NMR
spectra [0.3 (3) and 0.4 ppm (4)] are shifted downfield relative
to that of the free ligand (ꢀ19.3 ppm), as expected for
coordination to gallium. The FAB mass spectra show the
molecular ion peaks at m/z 408.9 (100.0%, [M+ + H]) for 3
and 450.9 (47.1%, [M+ + H]) (for 4) with the appropriate
isotopic distributions. The mass spectrum of 4 also exhibits a
peak at m/z 844.8 (4.8%) corresponding to the fragment
[2M ꢀ tBu]+, which suggests formation of a dinuclear
complex under MS conditions.
Fig.
2
Molecular structure of GatBu{PPh(2-SC6H4)2-k3S,S0,P}
(4) with thermal ellipsoids at 50% probability (only one of two
independent molecules in the asymmetric unit is shown). The
hydrogen atoms are omitted for clarity.
three-coordinate compound Ga(S-2,4,6-tBu3C6H2)3 (Ga–S
2.205(6) A)9 and the tetracoordinate amine tris-thiolato complex
Ga{(SC6H4-2-CH2)3N-k4N,S,S0,S00} (2.225(2)–2.233(2) A),10
but are comparable to those in 2 and in four-coordinate
phosphinothiolato complexes.7
Colourless crystals of 3 and 4 were obtained from Et2O at
room temperature. Complex 3 crystallises in orthorhombic
space group Pbca with eight molecules in the unit cell, and 4 in
The Ga–C bond lengths [1.942(2) A (3), 1.982(2) A (4)]
are slightly shorter than the Ga–Ctrisyl distance in
GaMe2{C(SiMe3)3}(THF) (2.046(2) A)11 due to the higher
effective positive charge of the gallium atoms caused by the
electronegative sulfur atoms. However, the Ga–C distances
are comparable to those observed for previously reported
related gallium complexes (GaR2{(SC6H4-2-PPh2)-k2S,P},
R = Me: 1.958(3)–1.959(4) A, tBu: 2.005(4)–2.017(4) A;
GatBu{(SC6H4-2-PPh2)-k2S,P}{SC6H4-2-PPh2)-kS} 1.977(3) A)7
and in other organogallium compounds.12
ꢀ
triclinic space group P1 with four molecules in the unit cell.
Two structurally independent molecules were found in the
asymmetric unit of 4, which differ only slightly in their bond
2ꢀ
lengths and bond angles (Table 2). The PS2
ligand is
coordinated in a pincer-like manner in both compounds, and
the coordination sphere is completed by a methyl group in 3
and a tert-butyl group in 4 (Fig. 2). The closeness of the
S–Ga–P bond angles to 901 indicates distorted square-planar
rather than tetrahedral coordination, which is in agreement
with the bite angles observed for all complexes containing the
PS22ꢀ pincer ligand. Thus, the atoms Ga1, C1, S1 and S2 in 4
are nearly coplanar (deviations from the mean plane: Ga1
0.345, S1 ꢀ0.104 , S2 ꢀ0.110, C1 ꢀ0.131 A).
The Ga–P bond lengths [2.3491(4) A (3), 2.3602(8) A (4)] are
in the expected range for gallium phosphine complexes, e.g.,
GaCl3(PMe3) 2.353(2) A,13 GaCl3{P(SiMe3)3} 2.379(5) A,14
Ga{(SC6H4-2-PPh2)-k2S,P}{(SC6H4-2-PPh2)-kS}2 2.3923(8) A.7
However, the Ga–P distances are shorter than in
[Me2GaPPh2]3 2.433(1) A,15 GaClMe2{CH2(PPh2)2-kP}
2.535(2) A16 or GaMe2{(SC6H4-2-PPh2)-k2S,P} 2.4602(8).7
The shorter Ga–P bond lengths in 3 and 4 compared with
other tetracoordinate organogallium complexes are probably
a result of the pincer-like coordination of the ligand.
The Ga–S bond lengths of 2.2794(5)–2.2858(5) A (3) and
2.2943(7)–2.3132(7) A (4) are larger than those found in the
Table 2 Selected bond lengths (A) and angles (1) in 3 and 4a
3
4a
Ga1–C19
Ga1–S1
Ga1–S2
Ga1–P1
1.942(2) Ga1–C1
2.2858(5) Ga1–S1
2.2794(5) Ga1–S2
2.3491(4) Ga1–P1
1.982(2)
[1.982(2)]
[2.2828(8)]
[2.2876(7)]
[2.3680(7)]
Decomposition of 4: [GaIII{PPh(2-SC6H4)-k2S,P-m-(2-SC6H4)-
2.2943(7)
2.3132(7)
2.3602(8)
kS0}2]2(m3-H)2GaII (Ga–Ga) (5), [Ga{PPh(2-SC6H4)2-
2
k3S,S0,P}]2 (Ga–Ga) (6), and [Ga{PPh(2-SC6H4)2-
k3S,S0,P}]2(m-S) (7)
C19–Ga1–S1 118.02(7)
C19–Ga1–S2 116.57(7)
S2–Ga1–S1
C19–Ga1–P1 125.16(7)
S1–Ga1–P1
S2–Ga1–P1
C2–S1–Ga1 102.85(5)
C8–S2–Ga1 101.65(5)
C1–P1–Ga1 103.28(5)
C7–P1–Ga1 101.54(5)
C13–P1–Ga1 125.14(5)
C1–Ga1–S1 113.79(7)
C19–Ga1–S2 119.37(7)
[121.42(6)]
[112.88(6)]
[112.31(3)]
[124.05(6)]
[89.90(3)]
When a toluene–n-hexane solution of 4 was kept at room
temperature in daylight a few very small colourless crystals
formed after more than three weeks. The 31P{1H} NMR
spectrum of the crystals exhibited two signals of almost equal
intensity at ꢀ15.8 and ꢀ16.5 ppm, assigned, on the basis of
X-ray single-crystal molecular structure determinations, to
compounds 5 and 6 (vide infra). There were no changes in
the 31P{1H} NMR spectra (C7D8) of a solution of 4 kept in the
dark for more than 60 days or recorded after several hours of
refluxing in toluene, but the formation of a small amount of 5
111.83(2)
S2–Ga1–S1
C1–Ga1–P1 125.07(6)
113.79(3)
89.33(2)
90.61(2)
S1–Ga1–P1
S2–Ga1–P1
90.90(3)
89.01(3)
[91.03(2)]
C5–S1–Ga1 101.89(7)
C17–S2–Ga1 103.53(7)
C6–P1–Ga1 101.26(6)
C18–P1–Ga1 103.96(6)
C11–P1–Ga1 125.97(7)
[102.90(7)]
[101.41(7)]
[102.70(6)]
[101.05(6)]
[127.81(6)]
a
Bond lengths and angles of the second independent molecule are
given in brackets.
ꢁc
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Scheme 2
and 6 was observed when the solution was exposed to daylight
for more than 20 days. Total decomposition of 4 was found
after an additional month (ca. 40 days) in daylight (signals
at ꢀ15.8, ꢀ16.6 ppm and a low intensity signal at ca.
ꢀ24.0 ppm).
HOMOꢀ1 and HOMOꢀ2 orbitals (Fig. 3) have GaꢀC bonding
character, so any transitions from these levels should weaken
this bond, as was observed experimentally. The lability of the
GaꢀC bond might also be associated with the high electrostatic
positive charges on these atoms (Ga + 0.603, C + 0.552).
1
The H NMR spectra of a solution (C6D6) of 4 exposed to
daylight for three months in a sealed NMR tube showed
additional signals at 4.74 (septet, CH2Q) and 1.60 (t, CH3)
ppm assigned to isobutene and at 0.85 ppm (d) corresponding
to isobutane,17 both formed, most probably, by recombination
of tert-butyl radicals,18 as shown before for other tert-butyl
containing organometallics.19
Complete decomposition of 4 was observed on irradiation
for 24 h with a UV lamp at 366 nm in toluene–n-hexane–C6D6
solution (Scheme 2, details in the ESIw). Besides 5 and 6,
at least 19 other products were formed, as indicated by
the 31P{1H} NMR spectrum. From the clear solution, on
standing, only a few crystals were formed which were identified
as [Ga{PPh(2-SC6H4)2-k3S,S0,P}]2(m-S) (7; Scheme 2).
Efforts to isolate and fully characterise compounds 5 and 6
spectroscopically were unsuccessful; only
products was obtained in all cases.
a mixture of
Gas-phase geometry optimisation of 4 at the B3LYP/
6-31G(d)20 level of theory reproduced fairly well the main
features of the observed structure (see ESIw). The electronic
spectrum of 4 was calculated (TD-DFT using the Spartan’06
package) in order to understand the nature of the absorbance
transitions. The experimental and calculated spectra, the
excitation energies for the first 10 singlet states and the shapes
of the main orbitals involved are available as the ESIw. The
Fig. 3 The shape of the HOMO orbitals of 4.
ꢁc
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Based on the theoretical studies, the first step in the
formation of 5, 6 and 7 can be described as homolytic cleavage
of the Ga–C bond in 4. The gallium(II) intermediates thus
formed may dimerise through Ga–Ga and Ga–H (5),
Ga–Ga (6) or Ga–S (7) bond formation. A similar mechanism
was proposed for formation of the organo-digallane
(ButGaGaBut)2(m-H)2[m-H2Ga(But)2]2.21 During the last few
decades many organo-digallanes22 have been synthesised
by various methods and with diverse structures, and their
reactivity has also been investigated.23 Inorganic digallane
chemistry is mainly represented by adducts of gallium(II)
halides,24 other inorganic digallanes reported so far
being the tetra(amido)digallane [Ga{(NSiMe3CH2)2CMe2}]2
(obtained from the reaction of (LiNSiMe3CH2)2CMe2
with Ga2Cl4(dioxane)2) and tetraalkoxy-substituted digallane
[Ga2(OtBu)2(m-OtBu)2]2 (Ga–Ga).25 Thus, the inorganic
dithiolato framework in the structure of 6 is unprecedented.
Fig. 4 Molecular structure of 6 with thermal ellipsoids at 50%
probability (only one of two independent molecules found in the
asymmetric unit is shown). The solvent molecules and hydrogen atoms
are omitted for clarity.
Molecular structures of complexes 5, 6 and 7
The crystal structures of 5, 6 and 7 were determined by X-ray
structure analysis. The molecular structure of 5 is of only
low accuracy due to limited crystal data. Complex 5 is a
tetranuclear compound with two types of gallium atoms:
two are connected via a Ga–Ga single bond (GaII2), and two
GaIII atoms which are connected with the Ga2 group by two
bridging hydrogen atoms through 3c–2e bonds. Since the
hydrogen atom could not be unambiguously located in the
X-ray structure analysis, an IR spectrum of the mixture
of crystals of 5 and 6 was recorded, which showed a
Ga–H vibration at 1603 cmꢀ1 (cf. Ga–H 1638 cmꢀ1 in
(ButGaGaBut)2(m-H)2[m-H2Ga(But)2]2),21 supporting the
proposed structure of compound 5.
Table 3 Selected bonds lengths (A) and bond angles (1) in 6a
Ga1–Ga2 2.3832(4) [2.3935(4)] S1–Ga1–S2 110.08(3) [111.41(3)]
Ga1–S1 2.3155(6) [2.2891(7)] S3–Ga2–S4 114.20(3) [108.51(2)]
Ga1–S2 2.2902(8) [2.3219(7)] S1–Ga1–Ga2 123.87(2) [112.86(2)]
Ga2–S3 2.3272(7) [2.2945(6)] S2–Ga1–Ga2 120.56(2) [123.67(2)]
Ga2–S4 2.3037(6) [2.3142(6)] S3–Ga2–Ga1 128.54(2) [122.51(2)]
Ga1–P1 2.3783(6) [2.3969(6)] S4–Ga2–Ga1 121.15(2) [121.99(2)]
Ga2–P2 2.3870(6) [2.3832(7)] P1–Ga1–Ga2 113.54(2) [126.18(2)]
Ga1–Ga2–P2 118.59(2) [115.84(2)]
S1–Ga1–P1
S2–Ga1–P1
S3–Ga2–P2
S4–Ga2–P2
87.53(2) [89.66(2)]
90.20(2) [86.50(2)]
84.26(2) [89.38(2)]
88.03(2) [88.48(2)]
a
Bond lengths and angles of the second independent molecule are
given in brackets.
ꢀ
Compound 6 crystallises in the triclinic space group P1 with
four molecules of the dimeric gallium(II) complex and five
toluene molecules in the unit cell (Fig. 4, Table 3).
Two structurally independent molecules were found in the
asymmetric unit of 6. Complex 6 is a dinuclear gallium(II)
shortest Ga–Ga bond known to date (2.343(2) A), observed in
[Li([12]crown-4)2][{Ga(Trip)2}2] (Trip = C6H2-2,4,6-iPr3).28
The Ga–S bond lengths are in the same range as those found
in complex 4 (2.2902(8)–2.3272(7) A), but they are shorter than
those found in [Ga{CH(SiMe3)2}{(SPPh2NPPh2S)-k2S,S}]2
(2.4047(8)–2.4450(8) A).22b The Ga–P bond lengths
(av. 2.3826 A) are slightly shorter than those in the gallium(II)
compounds [GaCl2(PEt3)]2 (2.4269(5) A),24e [GaI2(PHCy2)]2
(2.424(2) A), [GaI2(PHtBu2)]2 (2.446(1) A)24i and GaI2(PEt3)–
GaI(PEt3)–GaI2(PEt3) (2.404(3)–2.427(3) A).24h However, the
Ga–P distances are slightly longer than those observed in the
previously mentioned gallium(III) compounds, which indicates
the influence of the oxidation state of the metal atom. The
S–Ga–P bond angles of the pincer ligand are similar to those of
the starting material 4.
2ꢀ
compound in which each Ga atom is coordinated by a PS2
ligand in a pincer-like manner resulting in a highly distorted
tetrahedral arrangement for both gallium atoms, in which
Ga1, Ga2, S1 and S2 are virtually coplanar with deviations
of about 0.23, 0.08, 0.07 and 0.07 A from the mean plane,
respectively. The distortion of the tetrahedral geometry in Ga1
and Ga2 is apparent from P–Ga–S angles of 84.26(2) to
90.20(2)1 and S–Ga–Ga angles of 120.56(2) to 128.54(2)1.
The Ga–Ga distance of 2.3832(4) A is not significantly
shorter than the sum of covalent radii (2.44 A)26 or the
gallium–gallium distance in elemental gallium (2.442 A) and
is comparable to those found in other inorganic digallanes:
Ga2Cl4(dioxane)2 (Ga–Ga 2.406(1) A),24a Ga2I4(NH3)2
(Ga–Ga 2.498(7) A),24d Ga2I4(AsEt3)2 (Ga–Ga 2.428(7) A),24g
Ga2I4(PEt3)2 (Ga–Ga 2.444(2) A),24h Ga2I2L2 (where
The two independent molecules in the asymmetric unit differ
only slightly in their respective Ga–Ga, Ga–S and Ga–P bond
lengths.
t
A small amount of compound 7 was obtained as thin
colourless needles from a toluene–n-hexane–C6D6 solution of
4 which was irradiated with UV light at room temperature for
24 h. The compound crystallises in the monoclinic space group
C2/c with four molecules of 7 and four C6D6 molecules in the
L = NH2Cy, Ga–Ga 2.429(1) A; L = NH2 Bu, Ga–Ga
2.4243(9) A, L = PHCy2, Ga–Ga 2.437(2) A, L = PHtBu2,
Ga–Ga 2.4448(9) A),24i Ga2[Ga2I6] (Ga–Ga 2.388(5) A)24j or
[Ga{(NSiMe3CH2)2CMe2}]2 (Ga–Ga 2.385(1) A)25 and related
compounds with a Ga–Ga single bond,27 but longer than the
ꢁc
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standard literature procedure involving the 1 : 3 reaction of
t
GaCl3 with BuLi.29 PPh(2-HSC6H4)2 (PS2H2) was prepared
from thiophenol by ortho-lithiation/electrophilic substitution
by using Schlenk techniques and dry solvents.30 Toluene,
n-hexane, dimethoxydiethyl ether (diglyme), diethyl ether
and tetrahydrofuran (THF) were dried over sodium–
benzophenone, distilled under an atmosphere of dry argon
and stored over potassium mirror. CH3OH and CH3CN were
refluxed over CaH2, distilled and kept under nitrogen. C7D8
for NMR spectroscopy was used as purchased and kept under
inert atmosphere over potassium mirror. C6D6 was dried over
sodium–potassium alloy, filtered and kept under an inert
atmosphere over potassium mirror. CDCl3 was dried over
LiAlH4, distilled and kept over molecular sieves.
Fig. 5 Molecular structure of 7 with thermal ellipsoids at 50%
probability. The solvent molecules and hydrogen atoms are omitted
for clarity. S1 atom is located on a twofold axis. Symmetry transfor-
mations used to generate equivalent atoms: ꢀx + 1, y, ꢀz + 1/2.
Elemental analysis was performed with a Vario EL-Heraeus
microanalyzer. IR spectra were recorded with a Perkin-Elmer
System 2000 spectrometer in the range 4000–400 cmꢀ1 and
1
400–200 cmꢀ1 on KBr and CsI pellets, respectively. H (TMS
unit cell. Compound 7 is a dinuclear complex which contains
two almost identical Ga(PS2) fragments linked by a sulfido
bridge (Fig. 5, Table 4).
internal standard) and 31P (85% H3PO4 external standard)
NMR spectra were recorded on a Bruker Avance DRX-400
instrument. Mass spectra were recorded on a VG12-520
mass spectrometer (EI MS, 70 eV, 200 1C), FT-ICR-MS
Bruker-Daltonics ESI mass spectrometer (APEX II, 7 T) or
a MASPEC II spectrometer (FAB MS, matrix: 3-nitrobenzyl
alcohol). A Perkin-Elmer UV-Vis spectrophotometer with
1.0 cm quartz cells was used for absorbance studies.
In 7, each gallium atom is surrounded in a distorted
tetrahedral fashion by three sulfur atoms (two thiolato groups
and one bridging sulfido group) and one phosphorus atom,
with S–Ga–S bond angles between 109.23(3) and 116.59(3)1.
Moreover, the large S1–Ga1–P1 bond angle of 137.22(2)1 is
compensated by the small S3–Ga1–P1 and S2–Ga1–P1 bond
angles of 91.86(3) and 88.78(3)1, respectively. The Ga1–S2 and
Ga1–S3 bonds of the gallium thiolato groups (2.2757(8) and
2.2513(8) A) are slightly shorter than those observed in
compounds 4 and 6, and this could be attributed to less steric
hindrance. As expected, the Ga1–S1 bond length of the
bridging sulfido group (2.1876(7) A) is smaller than the
Ga–Sthiolate distances. In the trimer, [GatBu(py)(m-S)]3, a
longer Ga–Sbridge bond is observed (2.231(3)ꢀ2.253(3) A).12b
No significant differences between the Ga–P distances of 7 and
4 and 6 were observed.
B3LYP/6-31G(d) full geometry optimisations were performed
on model systems in which two phenyl substituents on
phosphorus and arsenic were replaced by hydrogen atoms,
by using the Spartan 06 package of programs (SPARTAN ’06
Wavefunction inc.).31 TD-DFT/TDA calculations were
carried out with the same package of programs.
The crystallographic data were collected on a CCD Oxford
Xcalibur S diffractometer, radiation MoKa (l = 0.71073 A),
o- and j-scan mode. Data reduction was carried out with
CrysAlisPro including empirical absorption correction with
SCALE3 ABSPACK.32 The structure refinement was carried
out by direct methods with SHELXS-9733 and was refined
using SHELXL-97.34 All non-hydrogen atoms were refined
anisotropically and H atoms were calculated on idealised
The Ga1ꢂ ꢂ ꢂGa10 distance (3.308 A) is shorter than the sum
of the van der Waals radii (3.74 A),8 which could be indicative
of some degree of Gaꢂ ꢂ ꢂGa interaction, as reported for
[NEt4]2[Ga2S2(SPh)4] (2.943 A).5
positions. Structure figures were generated with ORTEP.35
A
summary of data collection, structure solution and refinement
Experimental
details for compounds 2–4, 6 and 7 is given in Table 5.
General procedures
Synthesis of [NEt3H][Ga{PPh(2-SC6H4)2-j3S,S0,P}-
{PPh(2-SC6H4)2-j2S,S0}] (1)
All manipulations were carried out under an inert atmosphere
of dry nitrogen. nBuLi (2.2 M in n-hexane), tBuLi (1.47 M in n-
pentane), PPh4Cl, NEt3, GaCl3 and GaMe3 are commercially
available. GaCl3 was freshly sublimed before use. The synthesis
of GatBu3 was carried out with minor modification of the
Both the 1 : 1 and 2 : 1 reactions of PS2H2 with GaCl3 in the
presence of NEt3 gave 1. At room temperature a solution of
PS2H2 (1.27 g, 3.895 mmol) and NEt3 (0.791 g, 7.835 mmol,
1.09 ml) in methanol (48 ml) was slowly added dropwise to a
solution of freshly sublimed GaCl3 (0.35 g, 1.983 mmol) in
methanol (15 ml). The white precipitate that formed immediately
turned pale yellow during the reaction. The reaction mixture
was stirred at room temperature for 22 h, and the precipitate
was separated by filtration, washed with n-hexane and dried
in vacuo (yield 1.37 g, 1.671 mmol, 84% based on GaCl3). Very
small colourless crystals were obtained from a MeCN solution
at room temperature over a few weeks but were unsuitable for
Table 4 Selected bonds lengths (A) and bond angles (1) in 7
Ga1ꢂ ꢂ ꢂGa10
Ga1–S1
Ga1–S2
Ga1–S3
Ga1–P1
3.308
Ga1–S1–Ga10
S1–Ga1–S2
S1–Ga1–S3
S3–Ga1–S2
S1–Ga1–P1
S2–Ga1–P1
S3–Ga1–P1
98.24(4)
112.10(3)
109.23(3)
116.59(3)
137.22(2)
88.78(3)
2.1876(7)
2.2757(8)
2.2513(8)
2.3688(7)
91.86(3)
ꢁc
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Table 5 Summary of data collections, structure solution and refinement details for compounds 2–4, 6 and 7
2ꢂDiglyme
3
4
6
7
Empirical formula
FW
T/K
Crystal system
Space group
a/A
b/A
c/A
C66H60GaO3P3S4
1192.01
130(2)
Triclinic
ꢀ
P1
12.142(5)
14.078(5)
18.389(5)
97.013(5)
109.103(5)
99.798(5)
2873.1(17)
2
1.378
0.755
1240
0.3 ꢃ 0.12 ꢃ 0.08
2.56/26.02
46 215
C19H16GaPS2
409.13
130(2)
Orthorhombic
Pbca
15.8418(1)
14.3993(1)
15.8970(1)
90
90
90
3626.28(4)
8
1.499
1.832
1664
0.4 ꢃ 0.4 ꢃ 0.2
2.83/30.50
94 604
C22H22GaPS2
451.21
130(2)
Triclinic
ꢀ
P1
C44.75H36Ga2P2S4
903.36
130(2)
Triclinic
ꢀ
P1
C42H32Ga2P2S5
898.36
130(2)
Monoclinic
C2/c
21.4599(8)
10.1678(4)
18.2790(7)
90
95.722(3)
90
3968.6(3)
4
1.504
1.732
1824
0.3 ꢃ 0.02 ꢃ 0.02
2.79/28.27
50 091
11.064(2)
12.605(3)
15.919(3)
93.73(2)
102.65(2)
99.97(2)
2121.1(7)
4
1.413
1.573
928
0.4 ꢃ 0.2 ꢃ 0.2
2.57/28.28
38 133
12.439(1)
13.867(3)
24.722(1)
83.400(9)
83.011(6)
73.18(1)
4037.1(9)
4
1.486
1.653
1842
0.4 ꢃ 0.3 ꢃ 0.3
2.73/28.28
104 559
a/1
b/1
g/1
Volume/A3
Z
Dcalc/Mg mꢀ3
m (MoKa)/mmꢀ1
F(000)
Crystal size/mm3
y
Min/yMax/1
No. of reflns collected
No. of indep. reflns
Completeness to
11 299 [Rint = 0.0608] 5538 [Rint = 0.0213] 10 517 [Rint = 0.0378] 19 952 [Rint = 0.0437] 4922 [Rint = 0.0634]
99.9
99.9
99.9
99.6
99.9
y
Max(%)
Final R indices
R1 = 0.0325,
wR2 = 0.0429
R1 = 0.0698,
wR2 = 0.0483
0.950
R1 = 0.0262,
wR2 = 0.0588
R1 = 0.0354,
wR2 = 0.0686
1.228
R1 = 0.0280,
wR2 = 0.0565
R1 = 0.0504,
wR2 = 0.0618
0.919
R1 = 0.0293,
wR2 = 0.0549
R1 = 0.0554,
wR2 = 0.0627
1.027
R1 = 0.0377,
wR2 = 0.0808
R1 = 0.0662,
wR2 = 0.0914
1.031
[I 4 2s(I)]
R indices (all data)
Goodness-of-fit on F2
Largest diff. peak/eꢂAꢀ3 0.313 and ꢀ0.342
0.441 and ꢀ0.372
0.590 and ꢀ0.307
0.459 and ꢀ0.365
1.339 and ꢀ0.783
X-ray structure determination. Compound 1 is a pale yellow
solid, mp 223–240 1C, with low solubility in common solvents:
n-hexane, THF, CH2Cl2, Et2O, CH3CN.
1H NMR (d, CDCl3, ppm): 7.86–7.62 (m, 20H, phenyl),
7.43–6.80 (m, 26H, aryl). 31P{1H} NMR (d, CDCl3, ppm): 22.9
(PPh4), ꢀ23.9, ꢀ29.3 (br). Anal. calcd for C66H60GaO3P3S4
(M = 1192.01): C 66.50, H 5.07%; found: C 66.12, H 5.18%.
IR (KBr, cmꢀ1): 3051 (m), 2962 (w), 1911 (w), 1572 (s), 1545
(w), 1482 (m), 1436 (vs), 1420 (s), 1338 (w), 1315 (w), 1263 (m),
1245 (m), 1187 (w), 1159 (w), 1130 (m), 1109 (vs), 1049 (s),
1027 (s), 998 (w), 806 (w), 744 (vs), 723 (vs), 690 (s), 660 (w),
527 (vs), 475 (m), 453 (w), 409 (w). IR (CsI, cmꢀ1): 377 (s,
1H NMR (d, CDCl3, ppm): 7.52–6.91 (m, 26H, phenyl), 3.04
(q, 6H, HN(CH2CH3)3), 1.35 (t, 9H, HN(CH2CH3)3), N–H
proton was not observed. 31P{1H} NMR (d, CDCl3, ppm):
ꢀ23.9, ꢀ26.3 (br). Anal. calcd for C42H42GaNP2S4
(M = 820.71): C 61.47, H 5.16, S 15.63, N 1.71%; found:
C 60.97, H 5.20, S 15.54, N 1.67%. IR (KBr, cmꢀ1): 3044 (m),
2965 (m), 2675 (w, nN–H), 1571 (s), 1542 (w), 1480 (w), 1442 (s),
1420 (vs), 1263 (m), 1245 (m), 1155 (w), 1097 (s), 1047 (s), 1027
(s), 804 (w), 736 (vs), 720 (w), 694 (m), 659 (w), 535 (w), 519
(w), 473 (m), 456 (w), 492 (w). IR (CsI, cmꢀ1): 385 (m, nGa–S),
336 (w, nGa–S), 306 (w), 286 (w), 277 (m), 256 (m), 248 (m), 227
(s), 221 (m), 204 (w). ESI MS (negative, CHCl3–CH3CN
(1 : 1)), m/z: 716.96 ([Mꢀ ꢀ NEt3H]).
n
Ga–S), 360 (s), 337 (m, nGa–S), 304 (s), 283 (w), 265 (m), 253
(m), 221 (m). ESI MS (negative, CHCl3–CH3OH (1 : 1)), m/z:
1036.6, 732.9, 683.1, 464.9; no assignment possible. ESI MS
(positive, CHCl3–CH3OH (1 : 1)), m/z: 339.1 ([PPh4]+).
Synthesis of GaMe{PPh(2-SC6H4)2-j3S,S0,P} (3)
Compound 3 was obtained by treating PS2H2 with GaMe3
(1 : 1 or 2 : 1). Trimethylgallium (0.20 ml, 1.52 M in n-hexane,
0.05 g, 0.307 mmol) was added dropwise to a stirred solution
of PS2H2 (0.10 g, 0.307 mmol) in toluene (6 ml) at ꢀ78 1C.
During the addition of trimethylgallium vigorous evolution of
gas was observed. After addition was complete, the reaction
mixture was warmed to room temperature and stirred for
another 24 h. The volatiles were removed in vacuo resulting in
a white solid (yield: 0.05 g, 0.122 mmol, ca. 40% based on
PS2H2). The 2 : 1 reaction occurred with 80% yield of 3 based
on PS2H2. Colourless crystalline rods of 3 were obtained
on recrystallisation from Et2O at room temperature.
Mp 210–215 1C.
Synthesis of [PPh4][Ga{PPh(2-SC6H4)2-j3S,S0,P}-
{PPh(2-SC6H4)2-j2S,S0}] (2)
A solution of PPh4Cl (0.124 g, 0.331 mmol) in methanol (6 ml)
was added dropwise over 20 min to a suspension of 1 (0.273 g,
0.333 mmol) in the same solvent (18 ml). The suspension was
heated to reflux for 1 h and then stirred overnight at room
temperature; the precipitate was isolated by filtration and
dried in vacuo. The product, identified as compound 2
(yield: 0.21 g, 0.198 mmol, ca. 60% based on 1), is a white-
cream solid with mp 189–205 1C, slightly soluble in THF,
dichloromethane and diglyme but insoluble in diethyl ether
and n-hexane. However, 2 decomposes in THF in a few weeks.
A few colourless crystals suitable for X-ray diffraction were
obtained from a concentrated solution of 2 in diglyme at room
temperature in 3 days.
1H NMR (d, C6D6, ppm): 7.66 (t, 2H, phenyl), 7.07 (t, 2H,
aryl), 6.98–6.77 (m, 7H, aryl), 6.60 (t, 2H, aryl), 0.31 (s, 3H,
CH3). 31P{1H} NMR (d, C6D6, ppm): 0.3. Anal. calcd for
C19H16GaPS2 (M = 409.13): C 55.78, H 3.94, S 15.67; found:
ꢁc
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C 55.45, H 3.39, S 16.04%. IR (KBr, cmꢀ1): 3050 (w), 2964
(w), 1577 (s), 1547 (w), 1482 (w), 1447 (s), 1437 (s), 1422 (s),
1310 (w), 1251 (s), 1185 (w), 1131 (s), 1102 (s), 1046 (s), 1026
(m), 999 (w), 804 (m), 762 (s), 744 (vs), 706 (m), 690 (m), 582
(w), 542 (w), 523 (m), 513 (w), 475 (s), 450 (w), 434 (w). IR
(CsI, cmꢀ1): 398 (m, nGa–S), 354 (m, nGa–S), 302 (s), 278 (s),
268 (m), 227 (s), 222 (s). FAB MS, m/z: 408.9 (100.0%,
[M+ + H]), 392.9 (79.0%, [M+ ꢀ Me]), 325.0 (10.8%,
[PS2+]).
[Ga{PPh(2-SC6H4)2-k3S,S0,P}]2(m-S) (7). The Ga–Ga bond
(2.3832(4) A) in 6 is slightly shorter than observed for the
majority of digallane complexes, which could be due to steric
and electronic effects of the pincer ligand.
Acknowledgements
We thank Prof. J. Sieler for useful discussions. This work was
generously supported by the Deutscher Akademischer
Austauschdienst (DAAD) sandwich PhD grant for A.M.
Valean (A/06/09017), SOE, Programme CNCSIS-710 and
CEEX-OPTOLUM projects, Romania.
Synthesis of GatBu{PPh(2-SC6H4)2-j3S,S0,P} (4)
A slurry of PS2H2 (1.2 g, 3.681 mmol) in n-hexane (20 ml) was
cooled to ꢀ78 1C and GatBu3 (0.88 g, 3.651 mmol) was added
dropwise (over ca. 20 min). After addition was complete, the
reaction mixture was warmed to room temperature (a white
precipitate was observed) and stirred overnight. The white
precipitate was isolated by filtration and dried in vacuo (yield:
1.31 g, 2.905 mmol, 79% based on PS2H2). Colourless crystals
of 4 were obtained on recrystallisation from Et2O at room
temperature. Mp 186–193 1C.
References
1 See for example: (a) A. Hildebrand, P. Lonnecke, L. Silaghi-
¨
Dumitrescu and E. Hey-Hawkins, Dalton Trans., 2008,
´
´
4639–4646; (b) J. Real, E. Prat, A. Polo, A. Alvarez-Larena and
J. F. Piniella, Inorg. Chem. Commun., 2000, 3, 221–223;
(c) J. R. Dilworth, A. J. Hutson, J. S. Lewis, J. R. Miller,
Y. Zheng, Q. Chen and J. Zubieta, J. Chem. Soc., Dalton Trans.,
1996, 1093–1104; (d) D. H. Nguyen, H.-F. Hsu, M. Millar,
1H NMR (d, C6D6, ppm): 7.67 (t, 2H, phenyl), 7.17–6.84
(m, 7H, phenyl), 6.79 (t, 2H, phenyl), 6.61 (t, 2H, phenyl), 1.25
(s, 9H, C(CH3)3). 31P{1H} NMR (d, C6D6, ppm): 0.4. Anal.
calcd for C22H22GaPS2 (M = 451.21): C 58.56, H 4.91, S
14.21; found: C 58.06, H 5.69, S 14.23%. IR (KBr, cmꢀ1): 3049
(w), 2945 (m), 2914 (m), 2869 (m), 2843 (s), 2708 (w), 1963 (w),
1811 (w), 1577 (s), 1548 (w), 1482 (w), 1448 (s), 1422 (s), 1362
(w), 1333 (w), 1252 (s), 1176 (w), 1162 (w), 1133 (m), 1101 (s),
1046 (s), 1029 (m), 999 (w), 944 (w), 866 (w), 812 (w), 756 (s),
743 (vs), 718 (m), 704 (m), 690 (m), 522 (m), 512 (m), 474 (s),
450 (m), 431 (w). IR (CsI, cmꢀ1): 392 (s, nGa–S), 353 (w, nGa–S),
304 (s), 274 (s), 237 (m), 214 (w), 208 (w).
S. A. Koch, C. Achim, E. L. Bominaar and E. Munck, J. Am.
¨
Chem. Soc., 1996, 118, 8963–8964; (e) J. D. Franolic, M. Millar
and S. A. Koch, Inorg. Chem., 1995, 34, 1981–1982; (f) N. de Vries,
J. Cook, A. G. Jones and A. Davison, Inorg. Chem., 1991, 30,
2662–2665; (g) J. A. Cabezza, M. A. Martı
D. Ardura and S. Garcıa-Granda, Eur. J. Inorg. Chem., 2000,
499–503.
2 See for example: (a) P. Pe
Vazquez, J. Castro, A. Sousa, L. Cooper, J. R. Dilworth,
R. L. Richards, Y. Zheng and J. A. Zubieta, Inorg. Chim. Acta,
2003, 356, 193–202; (b) V. Gomez-Benıtez, S. Hernandez-Ortega
and D. Morales-Morales, Inorg. Chim. Acta, 2003, 346, 256–260;
(c) P. Perez-Lourido, J. Romero, L. Rodrıquez, J. A. Garcıa-
Vazquez, J. Castro, A. Sousa, J. R. Dilworth and
O. R. Nascimento, Inorg. Chem. Commun., 2002, 5, 337–339;
(d) D. Morales-Morales, S. Rodrıguez-Morales, J. R. Dilworth,
nez-Garcıa, V. Riera,
´ ´
´
´
rez-Lourido, J. Romero, J. A. Garcıa-
´
´
´
´
´
´
´
´
´
t
FAB MS, m/z: 844.8 (4.8%, [2M+ ꢀ Bu]), 450.9 (47.1%,
´
[M+ + H]), 392.9 (100.0%, [M+
ꢀ
tBu]), 325.0 (2.9%,
A. Sousa-Pedrares and Y. Zheng, Inorg. Chim. Acta, 2002, 332,
101–107; (e) E. Cerrada, L. R. Falvello, M. B. Hursthouse,
M. Laguna, A. Luquın and C. Pozo-Gonzalo, Eur. J. Inorg. Chem.,
´
[PS2+]).
2002, 826–833; (f) K. Ortner, L. Hilditch, Y. Zheng, J. R. Dilworth
and U. Abram, Inorg. Chem., 2000, 39, 2801–2806;
(g) J. R. Dilworth, D. V. Griffiths, S. J. Parrott and Y. Zheng,
J. Chem. Soc., Dalton Trans., 1997, 2931–2936; (h) J. R. Dilworth
and N. Wheatley, Coord. Chem. Rev., 2000, 199, 89–158.
3 (a) N. Froelich, P. B. Hitchcock, J. Hu, M. F. Lappert and
J. E. Dilworth, J. Chem. Soc., Dalton Trans., 1996, 1941–1946;
´ ´ ´
(b) P. Perez-Lourido, J. Romero, J. A. Garcıa-Vazquez, A. Sousa,
K. Maresca and J. Zubieta, Inorg. Chem., 1999, 38, 1293–1298;
(c) J. Aznar, E. Cerrada, M. B. Hursthouse, M. Laguna, C. Pozo
and M. P. Romero, J. Organomet. Chem., 2001, 622, 274–279.
4 (a) R. J. Wehmschulte, K. Ruhlandt-Senge and P. P. Power, Inorg.
Chem., 1995, 34, 2593–2599; (b) D.G. Hendershot, R. Kumar,
M. Barber and J. P. Oliver, Organometallics, 1991, 10, 1917–1922;
(c) A. Keys, S. G. Bott and A. R. Barron, Polyhedron, 1998, 17,
3121–3130; (d) C. Schnitter, A. Klemp, H. W. Roesky, H.-G.
Conclusions
The coordination chemistry of potentially tridentate ligand
PPh(2-HSC6H4)2 (PS2H2) toward gallium has been investigated.
t
Treatment of GaR3 (R = Cl, Me, Bu) with PS2H2 gives
anionic and neutral complexes, [Ga(PS2)2]ꢀ and GaR(PS2),
respectively. Crystals could be obtained only when the
bulky cation [PPh4]+ was employed as the counterion. The
gallium atom of the anion in 2 is coordinated in a distorted
trigonal-bipyramidal fashion resulting from unsymmetrical
2ꢀ
coordination of the two PS2
ligands. In the neutral
complexes 3 and 4, the Ga atom is coordinated in a distorted
Schmidt, C. Ropken, R. Herbst-Irmer and M. Noltemeyer, Eur.
¨
J. Inorg. Chem., 1998, 2033–2039.
tetrahedral fashion by one alkyl group and one pincer-like
2ꢀ
PS2 ligand. Irradiation of GatBu(PS2) (4) leads to decom-
5 L. E. Maelia and S. A. Koch, Inorg. Chem., 1986, 25, 1896–1904.
6 S. Suh, J. H. Hardesty, T. A. Albright and D. M. Hoffman, Inorg.
Chem., 1999, 38, 1627–1633.
´
7 A. M. Valean, S. Gomez-Ruiz, P. Lonnecke, I. Silaghi-Dumitrescu,
¨
L. Silaghi-Dumitrescu and E. Hey-Hawkins, Inorg. Chem., 2008, 47,
11284–11293.
8 A. Bondi, J. Phys. Chem., 1964, 68, 441–451.
9 K. Ruhlandt-Senge and P. P. Power, Inorg. Chem., 1991, 30,
2633–2637.
10 R. J. Motekaitis, A. E. Martell, S. A. Koch, J. W. Hwang,
D. A. Quarless Jr. and M. J. Welch, Inorg. Chem., 1998, 37,
5902–5911.
position, the mechanism of which can be described as
homolytic cleavage of the Ga–C bond based on TD-DFT
calculations using the Spartan’06 package. Three of the
products which were formed could be isolated, albeit only in
small amounts, and structurally characterised: tetranuclear
hydrido-bridged mixed-valent gallium(II)–gallium(III) complex
[GaIII{PPh(2-SC6H4)-k2S,P-m-(2-SC6H4)-kS0}2]2(m3-H)2GaII
2
(Ga–Ga) (5), gallium(II) complex [Ga{PPh(2-SC6H4)2-
k3S,S0,P}]2 (Ga–Ga) (6) and sulfido-bridged dinuclear complex
ꢁc
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11 C. Schnitter, H. W. Roesky, T. Albers, H.-G. Schmidt, C. Ropken,
¨
E. Parisini and G. M. Sheldrick, Chem.–Eur. J., 1997, 3,
23 (a) W. Uhl, Coord. Chem. Rev., 1997, 163, 1–32; (b) W. Uhl, Chem.
Soc. Rev., 2000, 29, 259–265; (c) Y. Wang and G. H. Robinson,
Organometallics, 2007, 26, 2–11.
24 See for example: (a) J. C. Beamish, R. W. H. Small and
I. J. Worrall, Inorg. Chem., 1979, 18, 220–223; (b) R. W. H.
Small and I. J. Worrall, Acta Crystallogr., Sect. B: Struct.
Crystallogr. Cryst. Chem., 1982, 38, 250–251; (c) R. W. H. Small
and I. J. Worrall, Acta Crystallogr., Sect. B: Struct. Crystallogr.
Cryst. Chem., 1982, 38, 86–87; (d) C. Doriat, M. Friesen, E. Baum,
1783–1792.
12 (a) V. Montiel-Palma, E. Huitro
´
M.-A. Munoz-Hernandez, V. Garcı
n-Rattinger, S. Corte
´
a-Montalvo, E. Lopez-Honorato
s-Llamas,
´
´
´
and C. Silvestru, Eur. J. Inorg. Chem., 2004, 3743–3750;
(b) M. B. Power, J. W. Ziller and A. R. Barron, Organometallics,
1992, 11, 2783–2790; (c) E. G. Gillan, S. G. Bott and A. R. Barron,
Chem. Mater., 1997, 9, 796–806; (d) C. C. Landry, A. Hynes,
A. R. Barron, I. Haiduc and C. Silvestru, Polyhedron, 1996, 15,
391–402.
A. Ecker and H. Schnockel, Angew. Chem., Int. Ed. Engl., 1997, 36,
¨
1969–1971; (e) S. Nogai and H. Schmidbaur, Inorg. Chem., 2002,
13 J. C. Carter, G. Jugie, R. Enjalbert and J. Galy, Inorg. Chem.,
1978, 17, 1248–1254.
14 J. F. Janik, R. A. Baldwin, R. L. Wells, W. T. Pennington,
G. L. Schimek, A. L. Rheingold and L. M. Liable-Sands, Organo-
metallics, 1996, 15, 5385–5390.
41, 4770–4774; (f) T. Duan and H. Schnockel, Z. Anorg. Allg.
¨
Chem., 2004, 630, 2622–2626; (g) B. Beagley, S. M. Godfrey,
K. J. Kelly, S. Kungwankunakorn, C. A. McAuliffe and
R. G. Pritchard, Chem. Commun., 1996, 2179–2180;
(h) A. Schnepf, C. Doriat, E. Mollhausen and H. Schnockel, Chem.
¨
¨
15 G. H. Robinson, J. A. Burns and W. T. Pennington, Main Group
Chem., 1995, 1, 153–158.
Commun., 1997, 2111–2112; (i) R. J. Baker, H. Bettentrup and
C. Jones, Eur. J. Inorg. Chem., 2003, 2446–2451; (j) G. Gerlach,
16 H. Schmidbaur, S. Lauteschlager and G. Muller, J. Organomet.
Chem., 1985, 281, 25–32.
17 The signal for the CH proton was not observed, probably due to
very low intensity.
W. Honle and A. Simon, Z. Anorg. Allg. Chem., 1982, 486, 7–21;
¨
¨
¨
(k) J. C. Beamish, A. Boardman, R. W. H. Small and I. J. Worrall,
Polyhedron, 1985, 4, 983–987; (l) N. Wiberg, T. Blank,
M. Westerhausen, S. Schneiderbauer, H. Schnockel, I. Krossing
¨
18 M. J. Gibian and R. C. Corley, Chem. Rev., 1973, 73,
441–464.
19 R. Benn, Chem. Phys., 1976, 17, 369–376.
and A. Schnepf, Eur. J. Inorg. Chem., 2002, 351–356; (m) G. Linti
and W. Kostler, Angew. Chem., 1996, 108, 593–595 (Angew. Chem.,
¨
Int. Ed. Engl., 1996, 35, 550–552); (n) A. Schnepf, E. Weckert,
20 (a) A. D. Becke, J. Chem. Phys., 1993, 98, 5648–5652; (b) C. Lee,
W. Yang and R. G. Parr, Phys. Rev. B: Condens. Matter, 1988, 37,
785–789; (c) P. J. Stephens, F. J. Devlin, C. F. Chabalowski and
M. J. Frisch, J. Phys. Chem., 1994, 98, 11623–11627;
(d) S. H. Vosko, L. Wilk and M. Nusair, Can. J. Phys., 1980, 58,
1200–1211.
21 W. Uhl, L. Cuypers, G. Geiseler, K. Harms and B. Neumuller,
¨
J. Chem. Soc., Dalton Trans., 2001, 2398–2400.
22 See for example: (a) W. Uhl, M. Layh and T. Hildenbrand,
J. Organomet. Chem., 1989, 364, 289–300; (b) W. Uhl, T. Spies
and W. Saak, Z. Anorg. Allg. Chem., 1999, 625, 2095–2102;
G. Linti and H. Schnockel, Angew. Chem., 1999, 111, 3578–3581
¨
(Angew. Chem., Int. Ed., 1999, 38, 3381–3383).
25 G. Linti, W. Kostler and A. Rodig, Z. Anorg. Allg. Chem., 2002,
¨
628, 1319–1326.
26 B. Cordero, V. Go
J. Echeverrıa, E. Cremades, F. Barraga
Trans., 2008, 2832–2838.
´
mez, A. E. Platero-Prats, M. Reve
´
s,
´
´
n and S. Alvarez, Dalton
27 (a) B. Twamley and P. P. Power, Angew. Chem., Int. Ed., 2000, 39,
3500–3503; (b) W. Uhl, R. Graupner, I. Hahn, T. Spies and
W. Frank, Eur. J. Inorg. Chem., 1998, 355–360.
28 X. He, R. A. Bartlett, M. M. Olmstead, K. Ruhlandt-Senge,
B. E. Sturgeon and P. P. Power, Angew. Chem., Int. Ed. Engl.,
1993, 32, 717–719.
29 (a) R. A. Kovar, H. Derr, D. Brandau and J. O. Callaway, Inorg.
Chem., 1975, 14, 2809–2814; (b) K. T. Higa and C. George,
Organometallics, 1990, 9, 275–277.
30 E. Block, G. Ofori-Okai and J. Zubieta, J. Am. Chem. Soc., 1989,
111, 2327–2329.
31 SPARTAN ‘06 Wavefunction Inc., W.I., 18401 Von Karman
Avenue, Suite 370, Irvine, CA 92612.
32 CrysAlisPro software, including empirical absorption correction
using spherical harmonics, implemented in SCALE3 ABSPACK
scaling algorithm, Oxford Diffraction Ltd., Abingdon, Oxfordshire,
England, 2006.
(c) W. Uhl, L. Cuypers, K. Schuler, T. Spies, C. Strohmann and
¨
K. Lehmen, Z. Anorg. Allg. Chem., 2000, 626, 1526–1534;
(d) K. S. Klimek, C. Cui, H. W. Roesky, M. Noltemeyer and
H.-G. Schmidt, Organometallics, 2000, 19, 3085–3090; (e) W. Uhl,
L. Cuypers, K. Harms, W. Kaim, M. Wanner, R. Winter, R. Koch
and W. Saak, Angew. Chem., Int. Ed., 2001, 40, 566–568;
(f) W. Uhl, Adv. Organomet. Chem., 2008, 51, 53–108;
(g) R. J. Baker, C. Jones, M. Kloth and J. A. Platts, Organo-
metallics, 2004, 23, 4811–4813; (h) W. Uhl, A. El-Hamdan,
G. Geiseler and K. Harms, Z. Anorg. Allg. Chem., 2004, 630,
821–828; (i) W. Uhl, F. Breher, S. Haddadpour, R. Koch and
M. Matar, Z. Anorg. Allg. Chem., 2004, 630, 1839–1845;
(j) W. Uhl, A. El-Hamdan, M. Prott, P. Spuhler and
¨
G. Frenking, Dalton Trans., 2003, 1360–1364; (k) A. H. Cowley,
33 G. M. Sheldrick, SHELXS-97, Program for solution of crystal
structures, University of Gottingen, Germany, 1997.
A. Decken and C. A. Olaza
´
bal, J. Organomet. Chem., 1996, 524,
¨
34 G. M. Sheldrick, SHELXL-97, Program for refinement of crystal
271–273; (l) N. J. Hardman, R. J. Wright, A. D. Phillips and
P. P. Power, Angew. Chem., 2002, 114, 2966–2968 (Angew. Chem.,
Int. Ed., 2002, 41, 2842–2844); (m) N. J. Hardman, R. J. Wright,
A. D. Phillips and P. P. Power, J. Am. Chem. Soc., 2003, 125,
2667–2679.
structures, University of Gottingen, Germany, 1997.
¨
35 (a) C. K. Johnson, ORTEP, Report ORNL-5138, Oak Ridge
National Laboratory, Oak Ridge, TN, 1976; (b) L. J. Farrugia,
J. Appl. Crystallogr., 1997, 30, 565–565.
ꢁc
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