Chalcogenides of aluminium(III) and gallium(III) derived from Lewis base adducts of alane and gallane

Article abstract of DOI:10.1039/a802243g

Reductive cleavage of (ER)₂ by [GaH₃L], L = NMe₃ or P(C₆H₁₁)₃, afforded [Ga(TePh)₃(NMe₃)], [Ga(SeEt)₃-(NMe₃)] and [Ga(TePh)₃{P(C₆H₁₁)3}]; the latter was also prepared by the reaction of [GaH₂Cl{P(C₆H₁₁)₃}] with LiTePh. They have slightly disordered tetrahedral metal centres, established in the solid for [Ga(TePh)₃(NMe₃)] and [Ga(TePh)₃ {P(C₆H₁₁)₃}], and in the structure of the aluminium analogue, [Al(SePh)₃(NMe₃)], which was also determined. Reaction of [GaH₂Cl {P(C₆H₁₁)₃}] with Li₂Se afforded dinuclear trans-[{GaCl(μ-Se)[P(C₆H₁₁)₃]}₂] (minor product) which is centrosymmetric with distorted tetrahedral metal centres associated with a planar Ga₂Se₂ ring system. Treatment of trans-[{AlH(μ-Se)(NMe₃)}₂] with tmen (=N,N,N′,N′-tetramethylethane-1,2-diamine), or [{AlH₃(tmen)}_x] with elemental selenium, afforded polymeric [{[AlH(μ-Se)]₂(tmen)}_α]. Cleavage of (EPh)₂ by trans-[{AlH(μ-Se)(NMe₃)}₂] gave trans-[{Al(μ-Se)(EPh)(NMe₃)}₂], E = S, Se or Te, also as centrosymmetric dinuclear species with planar Al₂Se₂ ring systems. Reaction of trans-[{AlH(μ-Se)(NMe₃)}₂] with 2 equivalents of NH(SiMe₃)₂ or 6-methyl-2-trimethylsilylaminopyridine gave the secondary amine metallated products trans-[{Al(μ-Se)[N(SiMe₃)₂](NMe₃)} ₂] (structurally authenticated as a centrosymmetric dinuclear species) and [{Al(μ-Se)(NC₅H₃NSiMe₃-2-Me-6)} ₂].

Full text of DOI:10.1039/a802243g

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Chalcogenides of aluminium(III) and gallium(III) derived from Lewis
base adducts of alane and gallane
Warren J. Grigsby,a Colin L. Raston,*,†,a Vicki-Anne Tolhurst,a Brian W. Skeltonb and
Allan H. Whiteb
a Department of Chemistry, Monash University, Clayton, Melbourne, Victoria 3168, Australia
b Department of Chemistry, University of Western Australia, Nedlands, Western Australia 6907,
Australia
Reductive cleavage of (ER)2 by [GaH3L], L = NMe3 or P(C6H11)3, afforded [Ga(TePh)3(NMe3)], [Ga(SeEt)3-
(NMe3)] and [Ga(TePh)3{P(C6H11)3}]; the latter was also prepared by the reaction of [GaH2Cl{P(C6H11)3}] with
LiTePh. They have slightly disordered tetrahedral metal centres, established in the solid for [Ga(TePh)3(NMe3)]
and [Ga(TePh)3{P(C6H11)3}], and in the structure of the aluminium analogue, [Al(SePh)3(NMe3)], which was also
determined. Reaction of [GaH2Cl{P(C6H11)3}] with Li2Se afforded dinuclear trans-[{GaCl(µ-Se)[P(C6H11)3]}2]
(minor product) which is centrosymmetric with distorted tetrahedral metal centres associated with a planar
Ga2Se2 ring system. Treatment of trans-[{AlH(µ-Se)(NMe3)}2] with tmen (=N,N,NЈ,NЈ-tetramethylethane-1,2-
diamine), or [{AlH3(tmen)}∞] with elemental selenium, afforded polymeric [{[AlH(µ-Se)]2(tmen)}∞]. Cleavage
of (EPh)2 by trans-[{AlH(µ-Se)(NMe3)}2] gave trans-[{Al(µ-Se)(EPh)(NMe3)}2], E = S, Se or Te, also as
centrosymmetric dinuclear species with planar Al2Se2 ring systems. Reaction of trans-[{AlH(µ-Se)(NMe3)}2]
with 2 equivalents of NH(SiMe3)2 or 6-methyl-2-trimethylsilylaminopyridine gave the secondary amine
metallated products trans-[{Al(µ-Se)[N(SiMe3)2](NMe3)}2] (structurally authenticated as a centrosymmetric
dinuclear species) and [{Al(µ-Se)(NC5H3NSiMe3-2-Me-6)}2].
Complexes containing aluminium or gallium bound to the
heavier chalcogen elements have recently gained prominence in
synthesis,1–3 and as single source precursors for generating films
of binary metal chalcogenides. 1:1 Lewis base adducts of
MMe3 (M = Al or Ga) with dimethylchalcogens are available,4,5
as are a variety of mono-, di- and tetra-nuclear chalcogenido-
and chalcogenolato-complexes.6–28 Mononuclear complexes
containing anionic chalcogenolate ligands, ERϪ, are either
three-co-ordinate, in [Ga{Se(2,4,6-But3C6H2)}2]6 and [Ga{TeSi-
(SiMe3)3}3],7 or four-co-ordinate, in [AlMe2(SePh)(PPh3)]8
and [M(ER)3(NMe3)] (M = Al, E = Se, R = Et, Ph or CH2Ph;
E = Te, R = Ph; and M = Ga, E = Se, R = Ph).9
centres each bearing a hydride. Finally, several ionic group
13/16 metal complexes have been structurally elucidated,
K[(AlMe3)3SeMe],27 K2[S(GaMe3)2],28 and [PPh4][GaTe2{(CH2-
NH2)2}2].29
Herein we report an extension of our studies on the reaction
of (RE)2, E = Se or Te, with Lewis base adducts of alane and
gallane showing that the reaction is general, leading to
[M(ER)3(NMe3)]. An earlier study dealt with the complexes
where M = Al, E = Se, R = Et, Ph or CH2Ph; E = Te, R = Ph;
and M = Ga, E = Se, R = Ph, and included the structural eluci-
dation of [Al(ER)3(NMe3)] (E = Se, R = Et; E = Te, R = Ph).9
We also report (i) reactions of trans-[{AlH(µ-Se)(NMe3)}2] with
(RE)2, N,N,NЈ,NЈ-tetramethylethane-1,2-diamine (tmen), and
bulky secondary amines, and (ii) the structure of trans-
[{GaCl(µ-Se)[P(C6H11)3]}2], isolated as a minor product from a
reaction of Li2Se with [GaH2Cl{P(C6H11)3}]. This is further to
our report on the reaction of trans-[{AlH(µ-Se)(NMe3)}2] with
N,N,NЈ,NЉ,NЉ-pentamethyldiethylenetriamine (pmdien) to give
the aforementioned tetranuclear cluster, [Al4H2(µ-Se)5(NMe3)4],
the sulfur analogue being independently prepared by the reac-
tion of [AlH3(NMe3)] with S(SiMe3)2.26 This was also the route
to [Al4(µ-S)6(NMe3)], the nature of the metal chalcogen core,
Al4S5 or Al4S6, depending on the ratio of reactants. The only
other reported reaction of the dinuclear species is that of trans-
[{AlH(µ-Se)(NMe3)}2] with (TePh)2 resulting in the formation
of trans-[{Al(µ-Se)(TePh)(NMe3)}2].18 The compounds trans-
[{AlH(µ-E)(NMe3)}2], E = Se or Te, are formed on treating
[AlH3(NMe3)] with elemental selenium or tellurium.17
Dinuclear complexes containing µ-bridging chalcogenide
ligands across two aluminum or gallium centres include
[{M[(Me3Si)2HC]}2E] (M = Al or Ga; E = S, Se or Te),10–15
[{Ga(mes)(NC5H4Me-4)(µ-Se)}2]
(mes = 1,3,5-Me3C6H2),16
trans-[{AlH(µ-E)(NMe3)}2] (E = Se or Te),17 and trans-[{Al-
(µ-E)(EPh)(NMe3)}2] which also has terminal chalcogenide
ligands.18 Then there are complexes with µ-bridging chalco-
genolate ligands, such as [{GaBut2(µ-EBut)}2] (E = Se or Te),19
[{Ga(Me3CCH2)2(µ-TePh)}2],20 [{AlBut2(µ-TeBut)}2],21 and
[{Al(mes)(µ-SeMe)}2].8
Tetranuclear clusters containing µ3-bridging chalcogenides
have cubane structures, [{M(ηn-C5Me5)(µ3-Se)}4] (M = Al, n = 5;
M = Ga, n = 1),22,23 [{Al(Me2EtC)(µ3-Se)}4]24 and [{Ga(η5-C5-
Me5)(η3-Te)}].12 Higher oligomers involving hexanuclear and
octanuclear complexes are also known.19,25 Tetranuclear clus-
ters with µ-bridging chalcogenide ligands across two metal
centres have recently been reported, notably [Al4(µ-S)6-
(NMe3)4]26 in which each S2Ϫ bridges two metal centres along
an edge of a tetrahedron of metal centres, and the closely
related complexes [Al4H2(µ-E)5(NMe3)4] (E = S26 or Se)18 where
one edge of the tetrahedron is open with the associated metal
Results and Discussion
Mononuclear tris(chalcogenolato)-aluminium(III) and
-gallium(III) complexes
Treatment of (trimethylamine) alane, [AlH3(NMe3)], and
(trimethylamine) gallane, [GaH3(NMe3)], with the diorganyl
† E-Mail: c.raston@sci.monash.edu.au
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dichalcogenides (RE)2 (E = Se or Te, R = alkyl or aryl) results
in chalcogen–chalcogen bond cleavage and the elimination
of hydrogen affording colourless, trichalcogenolato-
aluminium() and -gallium() complexes as mononuclear
adducts of trimethylamine.9 This method is a convenient one
step synthesis of Lewis base adducts of tris(chalcogenolato)
Group 13 metal complexes. New compounds reported here are
[Ga(TePh)3(NMe3)] and [Ga(SeEt)3(NMe3)]; previous work
focused on using [AlH3(NMe3)] and one example using
[GaH3(NMe3)], viz. [Ga(SePh)3(NMe3)]. A limiting factor in
using [GaH3(NMe3)] is its decomposition above 0 ЊC which
necessitates the use of freshly prepared material.30 The tri-
cyclohexylphosphine adduct of gallane is, in contrast, ther-
mally stable, and indeed is stable in air. It similarly reacts with
(TePh)2 affording yellow [Ga(TePh)3{P(C6H11)3}]. The same
complex has also been isolated from the reaction of [GaH2-
Cl{P(C6H11)3}] with LiTePh at room temperature in thf, and
has been structurally authenticated, along with [Ga(TePh)3-
(NMe3)] and a previously prepared aluminium compound
[Al(SePh)3(NMe3)].9 The new complexes have also been charac-
terised using NMR spectroscopy and microanalysis. The 31P
NMR chemical shift for [Ga(TePh)3{P(C6H11)3}], δ 68.6,
contrasts with δ 11.8 for [GaH3{P(C6H11)3}] and δ 9.2 for
P(C6H11)3, and may be related to steric compression within the
complex,31 which is reflected in the crystal structure (see below).
All reactions were carried out at room temperature in either
diethyl ether or toluene, depending on the solubility of (ER)2.
Reactions involving [GaH3(NMe3)] were sluggish whereas those
involving [AlH3(NMe3)] were often vigorous with evolution of
a gas,9 presumably hydrogen. The difference in the reactivity of
the two complexes reflects the difference in the polarity of the
M᎐H bonds in [MH3(NMe3)], M = Al or Ga.31 Using an excess
of [MH3(NMe3)], M = Al or Ga, gave tris(chalcogenolato)-
products rather than the redistribution compounds,
[MH(ER)2(NMe3)] and [MH2(ER)(NMe3)]. The new com-
plexes, including those previously reported, were obtained in
moderate to good yields. They exhibit good to high thermal
stability being stable to room temperature for weeks, and are
moisture and air sensitive, with the selenolato-complexes
decomposing to red products and tellurolato-complexes to
black materials which were not investigated.
The reactions most likely proceed via initial complexation of
the dichalcogen forming a mixed donor hypervalent metal
centre, at least for aluminium for which five-co-ordinate mixed
donor adducts have been reported.32,33 Hypervalent species
involving gallane are stable only at low temperature,30 and the
reluctance of gallium to be five-co-ordinate may account for
the different rates of formation of the tris(chalcogenolato)-
complexes.
No reaction was evident between BH3(NMe3) and (SePh)2,
(SeCH2Ph)2 or (TePh)2 in diethyl ether or toluene at room
temperature for times up to 17 h. We note that very few boron
chalcogenolato-complexes are known.33–35 The lack of reaction
is consistent with steric considerations, viz. the inability of
boron to form five-co-ordinate species, and the lower polaris-
ation of B᎐H bonds (<Ga᎐H < Al᎐H). Surprisingly no reac-
tion was evident between [AlH3(NMe3)] and (SCH2Ph)2 in
diethyl ether at room temperature over several hours. Here the
high S᎐S bond energy may be the problem, 425.01 kJ molϪ1
cf. 332.6 kJ molϪ1 for Se᎐Se, 264.4 kJ molϪ1 for Te᎐Te, but we
,
Scheme 1
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Fig. 1 Projection of [Al(SePh)3(NMe3)] with 20% thermal ellipsoids
for non-hydrogen atoms (as in other Figures); hydrogen atoms have
arbitrary radii of 0.1 Å. Selected bond distances (Å) and angles (Њ):
Se(1)᎐Al 2.343(8), Se(1)᎐C(1) 1.93(2), Se(2)᎐Al 2.365(8), Se(2)᎐C(7)
1.95(3), Se(3)᎐Al 2.355(8), Se(3)᎐C(13) 1.95(1) and Al᎐N 2.00(2);
Al᎐Se(1)᎐C(1) 101.3(8), Al᎐Se(2)᎐C(7) 100.1(8), Al᎐Se(3)᎐C(13)
100.0(8), Se(1)᎐Al᎐Se(2,3) 109.5(3), 114.0(3), Se(2)᎐Al᎐Se(3) 113.4(4),
N᎐Al᎐Se(1,2,3) 106.2(7), 106.3(7), 106.9(7) and Al᎐N᎐C(19,20,21)
111(2) (×3)
Fig. 3 Projection of [Ga(TePh)3{P(C6H11)3}]. Selected bond distances
(Å) and angles (Њ): Te(1)᎐Ga 2.598(2), Te(1)᎐C(11) 2.12(2), Te(2)᎐Ga
2.604(2), Te(2)᎐C(21) 2.12(2), Te(3)᎐Ga 2.576(2), Te(3)᎐C(31) 2.09(1)
and Ga᎐P(1) 2.419(5); Ga᎐Te(1)-C(11) 97.0(4), Ga᎐Te(2)᎐C(21)
110.3(3), Ga᎐Te(3)᎐C(31) 109.0(5), Te(1)᎐Ga᎐Te(2,3) 102.46(5),
119.66(7), Te(2)᎐Ga᎐Te(3) 106.96(8), P(1)᎐Ga᎐Te(1,2,3) 102.3(1),
110.7(1), 114.13(9) and Ga᎐P(1)᎐C(111,121,131) 106.9(5), 109.8(5),
107.3(6)
metal() complexes have been reported, e.g. [Ga{TeSi-
(SiMe3)3}3],7
[In{SeC(SiMe3)3}3],7
and
[Ga{Se(2,4,6-
But3C6H2)}3],6 but these are stabilised by the bulky nature of
the ligands. In this context we note that the structure of
In(SePh)3 is polymeric with six-co-ordinate metal centres and
forms mononuclear complexes on the addition of Lewis bases.37
The Al᎐Se bond distances in [Al(SePh)3(NMe3)], 2.343(8)–
2.365(8) Å, compare with 2.394(1) Å in [AlMe2(SePh)(PPh3)]8
and 2.37 Å in Al2Se3.38 The Ga᎐Te bond distances in
[Ga(TePh)3(NMe3)], 2.5725(9)–2.5804(9) Å, are similar to the
analogous distances in the aluminium complex, 2.518(2)–
2.589(2) Å. This is consistent with two metals having almost
identical covalent radii. As expected, the Ga᎐Te distances are
significantly shorter than those of the dinuclear complex
[{Ga(Me3CCH2)2(µ-TePh)}2], 2.755 Å (mean),20 and the cubane
Fig. 2 Projection of [Ga(TePh)3(NMe3)] down the Ga᎐N bond.
Selected bond distances (Å) and angles (Њ): Te(1)᎐Ga 2.5804(9),
Te(1)᎐C(1) 2.135(6), Te(2)᎐Ga 2.5725(9), Te(2)᎐C(7) 2.127(5),
Te(3)᎐Ga 2.575(1), Te(3)᎐C(13) 2.133(5) and Ga᎐N 2.095(4);
Ga᎐Te(1)᎐C(1) 97.6(1), Ga᎐Te(2)᎐C(7) 96.8(1), Ga᎐Te(3)᎐C(13)
96.9(1), Te(1)᎐Ga᎐Te(2,3) 112.66(3), 111.74(3), Te(2)᎐Ga᎐Te(3)
111.83(3), N᎐Ga᎐Te(1,2,3) 105.7(1), 106.6(1), 107.8(1) and
Ga᎐N᎐C(19,20,21) 110.1(4), 109.8(3), 109.8(3)
tetranuclear complex [{Ga(η1-C5Me5)(µ3-Te)}4], 2.671
Å
(mean).40 In contrast they are longer than the Ga᎐Te bond dis-
tances in the mononuclear three-co-ordinate species [Ga{TeSi-
(SiMe3)3}3], 2.488(4)–2.531 Å7 and [Ga{(Me3Si)2CH}2{TeSi-
(SiMe3)3}], 2.535(1) Å.10 All the above Ga᎐Te distances are
significantly shorter than those in Ga2Te5, 2.62 Å (mean).39
The Al᎐N distance in [Al(SePh)3(NMe3)], 2.00(2) Å, is simi-
lar to that in the tellurium analogue, 2.018(5) Å,9 both of which
are within the range typical for four-co-ordinate, monotertiary
amine adducts of aluminium species bearing strongly electron
withdrawing or electron releasing substituents attached to the
aluminium centres,41,42 and also with Al᎐N distances in
[{AlH(µ-E)(NMe3)}2] [E = Se, 2.0115(5) Å; Te, 2.011(9) Å]. The
Ga᎐N distance in [Ga(TePh)3(NMe3)], 2.095(4) Å, is also
typical for four-co-ordinate monotertiary amine adducts of
gallium species,43,44 but is longer than in the aluminium com-
plex. This is also the case for M᎐N distances in mononuclear
quinuclidine adducts of alane and gallane, 1.991(4)32 and
2.063(4) Å,45 respectively, and is related to the lower Lewis
acidity of gallane relative to alane.30
note that the dimeric species [{AlH(µ-Se)(NMe3)}2] reacts with
(SPh)2 (see below).
The crystal structures of [Al(SePh)3(NMe3)], [Ga(TePh)3-
(NMe3)] and [Ga(TePh)3{P(C6H11)3}], are shown in Figs. 1–3.
They are all mononuclear species with distorted tetrahedral (N
or P)ME3 metal centres. The compound [Ga(TePh)3(NMe3)] is
isostructural with [Al(TePh)3(NMe3)],9 having similar cell
dimensions in the monoclinic space group P21/c; [Al(SePh)3-
(NMe3)], in contrast, crystallises in the monoclinic space group
Cc and with dissimilar dimensions.
In all three structures the asymmetric unit is the mononuclear
species in which the metal centres are in slightly flattened tetra-
hedral environments and possessing a staggered conformation
about the M᎐N bond (M = Al or Ga) with the phenyl groups
in a propeller like arrangement. Other Group 13 metal
tris(selenolato)-complexes with a co-ordinated Lewis base are
The metal centres in [Al(SePh)3(NMe3)] and in the SeEt
analogue9 have slightly distorted flattened tetrahedral geom-
etries, marginally more than in the TePh analogue,9 but similar
to those in [Ga(TePh)3(NMe3)]: Se᎐Al᎐Se, 109.5(3), 113.4(4)
and 114.0(3), N᎐Al᎐Se 106.2(7), 106.3(7) and 106.9(7)Њ; cf.
[In(SePh)3(PPh3)2]36
and
Mononuclear three-co-ordinate trichalcogenolato Group 13
[{In[SeSi(SiMe3)3]3}2(µ-dmpe)].7
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Te᎐Ga᎐Te 111.74(3), 111.83(3) and 112.66(3)Њ, N᎐Ga᎐Te
105.7(1), 106.6(1) and 107.8(1)Њ in [Ga(TePh)3(NMe3)]. The
Ga᎐Te᎐C angles in [Ga(TePh)3(NMe3)], 96.8(1)–97.6(1)Њ, com-
pare with those in the aluminium analogue, 97.4(2)–97.6(2)Њ;9
Al᎐Se᎐C angles in [Al(SePh)3(NMe3)] are significantly larger at
100.0(8), 100.1(8) and 101.3(8)Њ which is a common feature
between analogous selenolato- and tellurolato-complexes, for
example in [{[Al(Me3Si)2HC]2}2E] (E = CH2, S, Se or Te).15
The N᎐M᎐E᎐C dihedral angles in both complexes range
over 74.7(3)–87(1)Њ thus reflecting the quasi-C3 symmetry of the
molecules. In contrast, for the P(C6H11)3 adduct, the corre-
sponding P᎐Ga᎐Te᎐C dihedral angles are Ϫ174.1(3), 81.5(6)
and 58.3(4)Њ.
distorted tetrahedral gallium centres. Only one related gallium
selenido complex has been previously reported, trans-[{Ga-
(mes)(µ-Se)(NC5H4Me-4)}2].16 The formation of dimers in
these complexes possessing Lewis base adducts contrasts with
tetranuclear cubane structures for alkyl/cyclopentadienyl
metal derivatives devoid of such bases,19,21,24,40 and [{(η-C5H5)-
(OC)2Fe(µ3-E)Ga}4] (E = S, Se or Te).48
Theoretical studies on [{AlH(µ3-E)}2] give an association
energy to the Al/Se tetramer of Ϫ42.58 kJ molϪ1 and formation
of a Lewis base solvated dimer, trans-[{AlH(µ-Se)(NMe3)}2],
from the unsolvated dimer has an association energy of
Ϫ136.11 kJ molϪ1 17
. Co-ordinative saturation of a monomeric
species [AlH(Se)(NMe3)2] is only 51.46 kJ molϪ1 less stable than
The compound [Ga(TePh)3{P(C6H11)3}] crystallises from
toluene in the monoclinic space group P21/c. The metal
environment is also a distorted tetrahedral PGaTe3 metal core
with a staggered conformation about the Ga᎐P bond. The
Ga᎐Te bond distances of 2.576(2)–2.604(2) Å are similar to
those in the trimethylamine adduct, and are elongated relative
to those in three-co-ordinate species.7,10 The Ga᎐P distance,
2.419(5) Å, is significantly shorter than that of the starting
complex [GaH3{P(C6H11)3}], 2.460(2) Å,46 but is typical for
Ga᎐P bond distances found in complexes with higher Lewis
acidity at the gallium centre such as in the monochlorogallane
complex [GaH2Cl{P(C6H11)3}], 2.403(4) Å.47
The Te᎐Ga᎐Te bond angles are quite varied at 102.46(5),
106.96(8) and 119.66(7)Њ, with the largest, Te(1)᎐Ga᎐Te(3),
having the phenyl substituent on Te(3) orientated towards the
Te(1) group, Fig. 3. The average of these angles, 109.7Њ, is
smaller than the narrower range of the corresponding angles in
the trimethylamine analogue, 111.74(3)–112.66(3)Њ. The larger
range of bond distances in the phosphine adduct can be attrib-
uted to the bulky nature of P(C6H11)3 resulting in different
orientations of the phenyl substituents on the tellurium centres.
The P᎐Ga᎐Te bond angles are also varied at 102.3(1), 110.7(1)
and 114.13(9)Њ, the latter associated with Te(1) which has its
phenyl substituent orientated away from the Te(3) plane to
alleviate steric congestion within the molecule [e.g. the
P᎐Ga᎐Te(1)᎐C(11) dihedral angle is Ϫ174.1(3)Њ]. Overall
the gallium has an unsymmetrically distorted tetrahedral
geometry.
the formation of a Lewis base dimer and free amine. The anion
[GaTe2{(CH2NH2)2}2]Ϫ 29 with formal Ga᎐Te double bonds
᎐
helps to support the feasibility of this type of structure.
However, attempts to prepare Lewis base adducts of ‘HAl᎐Se’
᎐
were unsuccessful. Treating trans-[{AlH(µ-Se)(NMe3)}2] with
tmen yielded a polymeric complex of composition [{[AlH(Se)]2-
(tmen)}∞], Scheme 1. The same complex was also prepared by
treating [{AlH3(tmen)}∞] with elemental selenium in toluene at
room temperature. It is only sparingly soluble in hydrocarbon
solvents and is involatile in vacuo, and most likely has a poly-
meric structure with the tmen bridging metal centres from
different dimers, in a similar mode to that found in the solid
state structure of [{AlH3(tmen)}∞].49 The presence of Al᎐H was
confirmed by IR [ν(Al᎐H) 1786 cmϪ1]. The reaction of complex
[{AlH(µ-Se)(NMe3)}2] and the tridentate ligand pmdien results
in the formation of [Al4H2Se5(NMe3)4] and possibly the ionic
complex [{AlH2 (pmdien)}2Se].18
The Ga᎐Te᎐C angles in [Ga(TePh)3{P(C6H11)3}], 97.0(4),
109.0(5) and 110.0(3)Њ, are significantly larger than those found
in the trimethylamine adduct, 96.8(1)–97.6(1)Њ, again most
likely due to the larger steric interactions within the molecule.
The smallest, 97.0(4)Њ, is associated with the tellurolate ligand
which deviates most from the approximately C3 symmetry of
the molecule, and is intuitively the angle closest to those in the
related, less strained, trimethylamine analogue.
Treating [AlH3{P(C6H11)3}] with elemental selenium and
tellurium results in oxidation of the phosphine to (C H ) P᎐E
᎐
11 3
4
rather than forming the corresponding dimeric phosphine/
hydride/selenide species, [{AlH(µ-Se)[P(C6H11)3]}2]. Attempts
to synthesize dimeric species by treating [AlH2Cl(NMe3)] with
elemental tellurium in a similar method to the synthesis of
[{AlH(µ-Te)(NMe3)}2] gave an unidentifiable complex, contain-
ing Al᎐H bonds (IR), which decomposed to a black material on
exposure to air. Similar reactions with Lewis base adducts of
gallane failed to give the analogous gallium chalcogenide com-
plexes. No reaction was evident between [GaH3(NMe3)] and
excess of tellurium powder prior to the gallane decomposing.
Using the more thermally robust Lewis base adducts of gallane,
namely [GaH3(quin)] (quin = quinuclidine) and [GaH3{NMe2-
(CH2Ph)}], also gave no reactions, even after heating in toluene.
The gallane reagents were recovered in high yield. In addition,
treating [GaH3{P(C6H11)3}] with either selenium or tellurium
Dinuclear selenido- and tellurido-complexes
The starting complexes here are trans-[{AlH(µ-E)(NMe3)}2],
E = Se or Te, which are prepared from the reaction of [AlH3-
(NMe3)] with an excess of elemental selenium or tellurium
powder.17 The related chlorogallium selenido complex trans-
[{GaCl(µ-Se)[P(C6H11)3]}2], Scheme 1, was prepared as a minor
product in the reaction of [GaH2Cl{P(C6H11)3}] and Li2Se. An
interesting aspect of this reaction is the preferential elimination
of LiH rather than of LiCl, although elimination of LiH has
previously been observed in the formation of the phosphine
adducts of gallane, [GaH3{P(C6H11)3}] and [(GaH3)2-
{(CH2PMe2)2}] from the treatment of LiGaH4 with P(C6H11)3
and (CH2PMe2)2, respectively,46 and in the synthesis of
[Ga(TePh)3{P(C6H11)3}] (see above).
powder also resulted in formation of (C H ) P᎐E (E = Se or
᎐
11 3
6
Te) as for reactions of [AlH3{P(C6H11)3}].
The mixed chalcogen aluminium complexes [{Al(µ-Se)-
(EPh)(NMe3)}2], E = S, Se or Te, were prepared by treating
trans-[{AlH(µ-Se)(NMe3)}2] with (EPh)2 and are associated
with cleavage of the E᎐E bonds and elimination of dihydrogen,
Scheme 1. Colourless crystals of the sulfur and selenium com-
pounds, and red crystals of the tellurium compound, were
grown from toluene solutions on slow cooling to 4 ЊC, the latter
being previously reported along with its crystal structure.18 The
structures of the sulfur and selenium compounds are reported
herein. Interestingly (SPh)2 is unreactive towards [AlH3(NMe3)]
In the solid state, molecules of dinuclear [{GaCl(µ-Se)-
[P(C6H11)3]}2] are centrosymmetric and are thus in the trans
arrangement, as for the aluminium chalcogenide complexes
trans-[{AlH(µ-E)(NMe3)}2], E = Se or Te.17 The central core has
µ-bridging seleniums in a strictly planar Ga2Se2 ring, with
2550
J. Chem. Soc., Dalton Trans., 1998, Pages 2547–2556

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lographically imposed 2/m symmetry. The toluene molecules
are disordered over two sites across twofold rotation axes, each
site with a 0.5 site occupancy.
The four-membered ring cores are planar, as found in the
dimeric aluminium selenolate complex [{Al(mes)(µ-SeMe)}2],8
where there is a methyl group attached to selenium. However,
the present complexes, along with trans-[{AlH(µ-Se)(NMe3)}2],
are the only complexes with µ-Se bridging two aluminium
centres which have been structurally authenticated.
The Al᎐(µ-Se) distances are uniform across the three com-
plexes, 2.344(2) [2.340(2)], 2.344(4) [2.344(4)], and 2.347(2)
[2.347(2)] Å for terminal S, Se, and Te, respectively, and thus
the presence of different chalcogenolate ligands does not
significantly influence the geometry of the four membered
Al2Se2 cores. The distances are slightly shorter than the corres-
ponding Al᎐Se distances, 2.359(2) Å, in trans-[{AlH(µ-Se)-
(NMe3)}2]. The Al᎐N distances are similar for the three
complexes, 1.998(4), 2.01(2) and 1.998(5) Å, respectively, and
comparable to the Al᎐N distance of 2.011(5) Å in trans-
[{AlH(µ-Se)(NMe3)}2].
The Al᎐E (terminal) distances, 2.243(2), 2.378(6) and
2.610(2) Å, respectively, vary according to increasing covalent
radii from sulfur to tellurium. The Al᎐S distance is longer than
that in the monomeric three-co-ordinate aluminium complexes
[Al{S(2,4,6-But3C6H2)}3] and [AlBun{S(2,4,6-But3C6H2)}2],
2.185(7) and 2.13(1) Å,51 respectively, but shorter than those
of the five-co-ordinate aluminium complex [AlH(SCH2CH2-
NEt2)2], 2.271(1) and 2.278(1) Å.52 It is also shorter than that
in the four-co-ordinate dinuclear thiolato complex [{AlMe2-
(µ-SC6F5)}2], 2.405(8) Å.53 The Al᎐Se (terminal) distance in
trans-[{Al(µ-Se)(SePh)(NMe3)}2] is significantly longer than the
Al᎐Se distances in the Al2Se2 core, but comparable with the
upper limit observed in [Al(SePh)3(NMe3)], and is considerably
shorter than that in the dinuclear complex [{Al(mes)2-
(µ-SeMe)}2], 2.519(2) Å.8 The Al᎐Te (terminal) distance
is slightly elongated compared to Al᎐Te in trans-[{AlH-
(µ-Te)(NMe3)}2], 2.586(4) and 2.580(4) Å, and [Al(TePh)3-
(NMe3)], 2.581(2)–2.589(2) Å, but shorter than in [{AlBut2-
(µ-TeBut)}2], 2.732(3) Å.21
Fig. 4 Projection of trans-[{Al(µ-Se)(SPh)(NMe3)}2]. Selected bond
distances (Å) and angles (Њ): Se᎐Al,AlЈ 2.344(2), 2.340(2), Al᎐N,S
1.998(4), 2.243(2); Al᎐Se᎐AlЈ 76.67(6), Se᎐Al᎐N,S,SeЈ 108.3(1),
119.96(7), 103.33(6), N᎐Al᎐S, SeЈ 98.7(1), 107.8(1), S᎐Al᎐SeЈ 118.03(9),
Al᎐N᎐C(01,02,03) 109.5(3), 111.5(3), 110.9(3), Al᎐S᎐C(1) 100.1(2).
Values for trans-[{Al(µ-Se)(SePh)(NMe3)}2]: Se(1)᎐Al 2.344(4),
Al᎐Se(2) 2.378(6) and Al᎐N(1) 2.01(2); Al᎐Se(1)᎐AlЈ 76.7(2),
C(1)᎐Se(2)᎐Al 96.3(6), N(1)᎐Al᎐Se(1) 108.8(3), Se(1)᎐Al᎐Se(1Ј)
103.3(2), N(1)᎐Al᎐Se(2) 99.3(5) and Se(1)᎐Al᎐Se(2) 118.0(2)
under the conditions studied (see above) yet reacts with trans-
[{AlH(µ-Se)(NMe3)}2]. This is despite the Al᎐H bonds in the
dimer being less polarised as judged by the difference in
ν(Al᎐H) 1780 cmϪ1 for [AlH3(NMe3)] cf. 1805 cmϪ1 for the
dimer.17,50
The compounds trans-[{Al(µ-Se)(EPh)(NMe3)}2], E = S, Se
or Te, are air and moisture sensitive decomposing to brown
solids. They have high thermal stability, being stable up to their
melting points. They have been characterised using 1H and 13
C
NMR spectroscopy (although low solubility of the sulfur
analogue precluded obtaining satisfactory 13C NMR data),
elemental microanalysis, and crystal structure determinations.
Crystals of the sulfur compound were mounted under an
atmosphere of argon and sealed in capillary tubes and the data
collected at room temperature, whereas those of the selenium
compound were coated in paraffin oil and the data collected at
Ϫ100 ЊC. They are the first authenticated complexes which
exhibit both bridging and terminally bound Group 16 moieties
with a Group 13:Group 16 element ratio of 1:2. The com-
pounds with E = S or Te are the first mixed chalcogen alu-
minium complexes structurally elucidated where both chalco-
gen moieties are bound to aluminium, and the compound with
E = Se is the first aluminium selenide complex where the Al:Se
ratio is 1:2 and the complex exhibits both µ-bridging selenide
groups and terminally bound selenolato moieties.
The compounds trans-[{Al(µ-Se)(EPh)(NMe3)}2], E = S or
Se, are dimeric in the solid state, as is the tellurium analogue.18
All complexes are centrosymmetric and thus the chalcogenolato
substituents have trans arrangements with respect to each other,
and the four-membered Al2Se2 ring core is strictly planar,
Fig. 4. This type of arrangement is common within Group
13/Group 16 compounds, e.g. [{Ga(mes)(µ-Se)(NC5H4-
Me-4)}2]16 and [{AlBut2(µ-TeBut)}2].21
The (PhE)Al᎐Se᎐Al(EPh) angles, 76.67(6), 76.7(2) and
76.37(6)Њ, respectively for E = S, Se or Te are slightly smaller
than that of the parent dimer trans-[{AlH(µ-Se)(NMe3)}2],
76.90(7)Њ. The µ-Se᎐Al᎐µ-Se angles, 103.33(6), 103.3(2) and
103.63(6)Њ, respectively, are correspondingly slightly larger than
that of the parent dimer, 103.10(7)Њ. The µ-Se᎐Al᎐E angles are
considerably larger than ideal tetrahedral values and decrease
slightly in the series E = S, 119.6(7) and 118.03(9), Se, 118.0(2),
and Te, 117.16(7) and 117.31(7)Њ. In the same series the
Al᎐EЈ᎐C angles decrease, 100.1(2), 96.3(6) and 94.6(1)Њ, due to
the increasing influence of the stereochemically active lone pair
of electrons on the chalcogen centres. The Al᎐N᎐C angles are
close to ideal tetrahedral values at 109.5(3)–111.5(3), 109.6(9)
and 109.8(4)–110.2(4)Њ, respectively, and are slightly smaller
than the corresponding angles in the parent dimer trans-
[{AlH(µ-Se)(NMe3)}2], 113.0(4)Њ. All other bond distances,
including S, Se, Te-C, and angles within the molecules are
unexceptional.
Treatment of [{AlH(µ-Se)(NMe3)}2] with 2 equivalents of
the secondary amines NH(SiMe3)2 or 6-methyl-2-trimethyl-
silylaminopyridine in toluene at room temperature results
in metallation of the secondary amine to form the amido-
aluminium selenide complexes [{Al(µ-Se)[N(SiMe3)2](NMe3)}2]
and [{Al(µ-Se)(NC5H3NSiMe3-2-Me-6)}2], respectively, with
the expulsion of dihydrogen, Scheme 1. Both complexes are air
and moisture sensitive, decomposing to red material, and were
isolated in modest to good yields. They were characterised by
1H and 13C NMR spectroscopy (a pure NMR sample was not
obtained for the latter complex and a 13C NMR spectrum could
not be obtained), and by crystal structure determination for
[{Al(µ-Se)[N(SiMe3)2](NMe3)}2].
The compound trans-[{Al(µ-Se)(SPh)(NMe3)}2] is isostruc-
tural with trans-[{Al(µ-Se)(TePh)(NMe3)}2],18 crystallising in
space group P21/c (P21/n). The molecules have crystallographic
imposed inversion centres but they approximate to 2/m sym-
metry with the Se᎐Se vector defining the rotation axis. The
compound trans-[{Al(µ-Se)(SePh)(NMe3)}2] crystallises as a
toluene solvate in C2/m with the dimers now having crystal-
J. Chem. Soc., Dalton Trans., 1998, Pages 2547–2556
2551

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Fig. 5 Projection of trans-[{Al(µ-Se)[N(SiMe3)2](NMe3)}2]. Selected
bond distances (Å) and angles (Њ): Se᎐Al,AlЈ 2.357(1), 2.353(1),
Al᎐N(1),N(2) 1.842(3), 2.033(3), N(1)᎐Si(11,12) 1.730(3), 1.740(4);
Al᎐Se᎐AlЈ 80.09(4), Se᎐Al᎐N(1,2),SeЈ 119.6(1), 104.6(1), 99.91(5),
N(1)᎐Al᎐N(2),SeЈ 105.6(1), 120.7(1), N(2)᎐Al᎐SeЈ 104.7(1),
Al᎐N᎐Si(11,12) 120.2(2), 120.6(2), Al᎐N(2)᎐C(21,22,23) 110.9(3),
109.9(3), 112.1(3)
Fig. 6 Projection of trans-[{GaCl(µ-Se)[P(C6H11)3]}2]. Selected bond
distances (Å) and angles (Њ): Se᎐Ga,GaЈ 2.365(2), 2.375(2), Ga᎐Cl,P
2.211(4), 2.418(4), P᎐C(11,12,13) 1.84(1), 1.84(1), 1.85(1); Ga᎐Se᎐GaЈ
77.06(6), Se᎐Ga᎐Cl,P,SeЈ 114.2(1), 115.1(1), 102.94(7), Cl᎐Ga᎐P,SeЈ
99.3(1), 114.3(1), P᎐Ga᎐SeЈ 111.6(1), Ga᎐P᎐C(11,21,31) 113.3(4),
112.8(4), 105.8(4)
¯
The complex crystallises from toluene in space group P1
with the dinuclear molecules disposed about inversion centres,
and the aluminium centres in distorted tetrahedral geo-
metries, Fig. 5. The complex possesses non-crystallographic
2/m symmetry with the two selenium centres defining the
quasi-C2 rotation axis. The amide ligands are arranged trans
with respect to each other and the four-membered Al2Se2
ring core, analogous to the parent compound [{AlH(µ-Se)-
(NMe3)}2],17 and the above dimers. The compound [{Al(µ-Se)-
(NC5H3NSiMe3-2-Me-6)}2] is likely to have a similar dimeric
structure, Scheme 1, with the N-donor groups of the amide
displacing trimethylamine forming strained four-membered
chelate rings for which there is precedence in some antimony
and bismuth chemistry.54
(amine)᎐Al᎐Se and N (amine)᎐Al᎐N (amide) bond angles of
104.6(1) and 104.7(1) and 105.6(1)Њ, respectively, are close to
tetrahedral values, N (amide)᎐Al᎐Se angles being much larger,
119.6(1) and 120.7(1)Њ.
The compound trans-[{GaCl(µ-Se)[P(C6H11)3]}2] crystallises
¯
as yellow prisms from toluene in space group P1, with the
centrosymmetric molecules disposed about inversion centres,
and with a planar four-membered Ga2Se2 ring core as for
the above dinuclear species, Fig. 6. A toluene of crystallis-
ation is disordered over inversion centres, over two sites of
equal population. The complex approximates to 2/m symmetry
with the rotation axis passing through the two selenium
centres.
The planar M2Se2 core of trans-[{Al(µ-Se)[N(SiMe3)2]-
(NMe3)}2] is related to the analogous core of trans-[{Ga(mes)-
(µ-Se)(NC5H3Me-4)}2],16 as is the arrangement of donor lig-
ands. The Al᎐Se distances, 2.357(1), 2.353(1) Å, are unchanged
from those of the parent dimer trans-[{AlH(µ-Se)(NMe3)}2],
2.359(2), 2.359(2) Å, but are slightly longer than trans-[{Al-
(µ-Se)(EPh)(NMe3)}2] which range from 2.340(2) to 2.347(2) Å.
The Al᎐N (amido) distance, 1.842(3) Å, is comparable to that
in [{AlMe2[N(SiMe3)2]}2(diox)] (diox = 1,4-dioxane), 1.848(8)
Å,55 and [AlH(Cl){N(SiMe3)2}(NMe3)], 1.823(4) Å,56 and as
expected57 is shorter than that in the amido-bridged complex
[{Al(NMe2)2(µ-NMe2)}2], 1.959(2) and 1.980(2) Å.58 The Al᎐N
(amine) distance is considerably longer at 2.033(3) Å, and long-
er than in the parent complex, the above dinuclear compounds,
and [AlH(Cl){N(SiMe3)2}(NMe3)], 2.016(5) Å.56 The N᎐Si
distances [1.730(3), 1.740(4) Å] are comparable to those in
other [bis(trimethylsilyl)amido]aluminium complexes such as
[Al{N(SiMe3)2}3], 1.75(1) Å,59 [{AlMe2[N(SiMe3)2]}2(diox)],
1.715(8) Å,57 and [AlH(Cl){N(SiMe3)2}(NMe3)] 1.748(4),
1.731(4) Å.56 Moreover they are longer than in the essentially
ionic Group 1 metal amide complexes such as {Na[N-
(SiMe3)2]}∞, 1.687(2) and 1.694(2) Å.60
The Al᎐Se᎐Al angle, 80.09(4)Њ, and Se᎐Al᎐Se angle,
99.91(5)Њ, correspond to a diamond shaped ring core which is
significantly different to that observed in the Al2Se2 ring core of
the parent complex, trans-[{AlH(µ-Se)(NMe3)}2], Al᎐Se᎐Al
and Se᎐Al᎐Se at 76.90(7) and 103.10(7)Њ,17 and also the ring
core in the above dinuclear complexes. This is likely to be due to
the large steric hindrance around the aluminium centre
imposed by N(SiMe3)2 which also manifests itself in the overall
flattened tetrahedral geometry of the metal centres. The N
The complex is best described as a tricyclohexylphosphine
Lewis base stabilised chloro, selenide-bridged gallium() spe-
cies with the metal centres in distorted tetrahedral geometries.
The selenium atoms are µ-bridging two gallium centres and
only one such gallium complex has been reported, viz.
[{Ga(mes)(µ-Se)(NC5H4Me-4)}2],16 which has similar Ga᎐Se
distances to these in the present structure, 2.3872(13) and
2.3784(12) Å,51 cf. 2.635(2) and 2.375(2) Å. As expected these
are shorter than in the triply bridged system [{Ga(η-C5Me5)-
(µ3-Se)}4], 2.4454(8)–2.4992(8) Å.23 The selenolate-bridged
dinuclear complex [Ga{Ph2(µ-SeMe)}2]8 also has Ga᎐Se dis-
tances considerably longer, as expected, at 2.493(1) and 2.509(1)
Å.8 However, the Ga᎐Se bond distances in [{(Me3Si)2CH}2-
Ga(µ-Se)Ga{CH(SiMe3)2}2], 2.3439(5) Å,15 are significantly
shorter than in the present structure, which may be related to
the absence of strain associated with a Ga2Se2 ring core in
[{(Me3Si)2CH}2Ga(µ-Se)Ga{CH(SiMe3)2}2].
The Se᎐Ga᎐Se angle, 102.94(7)Њ, compares with 100.13(4)Њ
in {Ga(mes)(µ-Se)(NC5H4Me-4)}2];16 the associated Ga᎐Se᎐
GaЈ angles are 76.06(6) and 79.87(4)Њ respectively. The
Se᎐Ga᎐Se and Ga᎐Se᎐Ga angles in [{GaPh2(µ-SeMe)}2] are
96.93(2) and 83.07(2)Њ,8 respectively, giving a more nearly
square four-membered ring core. In the less strained complex
[{(Me3Si)2CH}2Ga(µ-Se)Ga{CH(SiMe3)2}2] the Ga᎐Se᎐Ga
angle is 113.45(3)Њ.15 The Cl᎐Ga᎐Se and P᎐Ga᎐Se angles in the
present compound are more open at 114.2(1) and 114.3(1) and
115.1(1) and 111.6(1)Њ, respectively, but the Cl᎐Ga᎐P bond
angle is smaller at 99.3(1)Њ. All other bond distances, including
Ga᎐Cl and Ga᎐P, and angles within the molecule are
unexceptional.
2552
J. Chem. Soc., Dalton Trans., 1998, Pages 2547–2556

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(NMe3)] (0.16 g, 1.21 mmol) in toluene (ca. 30 cm3) at room
Conclusion
temperature. Slight gas evolution was observed upon addition.
The mixture was stirred for 16 h whereupon it was filtered and
the solvent removed in vacuo. Recrystallisation from toluene
(ca. 10 cm3) at 4 ЊC afforded pale yellow crystals (0.23 g, 66%),
m.p. 90–91 ЊC (Found: C, 23.77; H, 5.42; N, 3.02. Calc. for
C9H24GaNSe: C, 23.87; H, 5.34; N, 3.09%). 1H NMR (200
MHz, C6D6, 25 ЊC): δ 2.83 (6 H, q, 3JHH 7.4, CH2), 1.96 (9 H, s,
We have shown that Lewis base adducts of alane and gallane
are useful reagents for
a one step synthesis of tris-
(chalcogenolato)-complexes of the two metals, via reductive
cleavage of (ER)2. The reactions of trans-[{AlH(µ-Se)-
(NMe3)}2] with (ER)2, also reductive cleavages, represent a
simple route to mixed chalcogen containing species, with the
integrity of the dinuclear core maintained. This offers scope
for the synthesis of a wide range of mixed chalcogenides. In
addition we have shown that trans-[{AlH(µ-Se)(NMe3)}2] is a
useful reagent for building up novel mixed amido/chalcogenide
species and the simple metallation reaction has potential for
generating other mixed anionic ligand/chalcogenide species.
3
NCH3) and 1.52 (9 H, t, JHH 7.4 Hz, CH3). 13C NMR (50.3
MHz, C6D6, 25 ЊC): δ 46.9 (NCH3), 20.2 (CH2) and 14.3
(CH3).
[Ga(TePh)3{P(C6H11)3}]. A red solution of (TePh)2 (0.36 g,
0.89 mmol) in toluene (ca. 20 cm3) was slowly added to a stirred
solution of [GaH3{P(C6H11)3}] (0.21 g, 0.60 mmol) in diethyl
ether (ca. 20 cm3) at room temperature. The red mixture was
stirred for 11 h whereupon it was filtered and the solvent
removed in vacuo. Recrystallisation from diethyl ether (ca.
10 cm3) at Ϫ30 ЊC afforded yellow crystals (0.30 g, 52%),
m.p. > 100 ЊC (decomp.) (Found: C, 44.08; H, 6.17; P, 3.35.
Calc. for C36H48GaPTe3: C, 44.84; H, 5.02; P, 3.21%). 1H NMR
(200 MHz, C6D6, 25 ЊC): δ 8.12–8.08 (6 H, m, o-H of C6H5),
7.17–6.90 (9 H, m, m- and p-H of C6H5) and 1.82–0.83 (33 H,
m, PC6H11). 13C NMR (50.3 MHz, C6D6, 25 ЊC): δ 141.3,
129.0, 129.0 (d, J = 4.02), 126.7 (d, J = 5.48 Hz), 125.6 (C6H5),
39.2, 35.1, 34.0, 28.8–25.8 (m) and 21.4 (C6H11). 31P NMR
(121.5 MHz, C6D6, 25 ЊC): δ 68.6.
Experimental
General procedure
Preparative work was routinely carried out under an atmos-
phere of high purity argon. Proton spectra were recorded on
Varian Gemini 200 and Mercury spectrometers operating at
200 and 300 MHz, respectively, or on Bruker AC200 and
AM300 spectrometer operating at 200 and 300 MHz, respect-
ively, 13C NMR spectra on the same spectrometers operating at
50.3 and 75.7 MHz, using broad band decoupling or DEPT
pulse sequences, and 31P NMR spectra on a Varian Gemini
spectrometer operating at 81.0 MHz or a Bruker AM300
spectrometer operating at 121.5 MHz. Elemental analyses were
performed by Chemical and Microanalytical Services Pty, Ltd.
(CMAS), Melbourne. Melting points were determined in sealed
glass capillaries under argon or in vacuo, where appropriate,
and are uncorrected.
[{GaCl(ì-Se)[P(C6H11)3]}2]. Superhydride (LiBHEt3) (2.55
cm3 of a 1.0  solution in thf, 2.55 mmol) was added to a slurry
of selenium powder (0.48 g, 6.08 mmol) in toluene (ca. 103) at
room temperature. A white precipitate formed upon addition.
The reaction mixture was allowed to stir at room temperature
for 30 min. To this was added a solution of [GaH2-
Cl{P(C6H11)3}] (0.92 g, 2.37 mmol) in toluene (ca. 20 cm3) at
room temperature. The reaction mixture was allowed to stir for
17 h at room temperature. The resulting yellow solution was
filtered leaving a white precipitate when the solvent volume was
reduced in vacuo (ca. 15 cm3). Recrystallisation from toluene
(ca. 5 cm3) at Ϫ30 ЊC afforded a yellow prismatic crystal of
[{GaCl(µ-Se)[P(C6H11)3]}2] as a minor product.
Materials
Tetrahydrofuran, toluene, hexane, and diethyl ether were
refluxed over sodium wire or Na/K alloy. Benzene was refluxed
over sodium wire. All solvents were freshly distilled, freeze-
degassed prior to use and stored over a potassium mirror.
Selenium and tellurium powder, diphenyl ditelluride, diphenyl
diselenide, diphenyl disulfide, dibenzyl diselenide, dibenzyl
disulfide, tricyclohexylphosphine, lithium aluminium hydride,
gallium chloride, lithium hydride, bis(trimethylsilyl)amine,
tmen and pmdien were from Aldrich; tmen was purified and
dried by distillation over sodium wire before use. Other reagents
were used as received. The compounds [Al(SePh)2(NMe3)],9
trans-[{AlH(µ-E)(NMe3)}2], E = Se or Te,17 (trimethylamine)-
alane,61 lithium gallium hydride and (trimethylamine)gallane,62
tricyclohexylphosphine alane,63 (tricyclohexylphosphine)-
gallane,46 (tricyclohexylphosphine)gallane monochloride,47 6-
methyl-2-trimethylsilylaminopyridine64 and Li2Se65 were pre-
pared using variations of the literature procedures.
[{Al(ì-Se)(SPh)(NMe3)}2]. A colourless solution of (SPh)2
(0.53 g, 2.43 mmol) in toluene (ca. 10 cm3) was added to
a colourless solution of [{AlH(µ-Se)(NMe3)}2] (0.80 g, 2.41
mmol) in toluene (ca. 30 cm3) at room temperature. Gas evolu-
tion was observed. The resulting white solution was allowed to
stir for 17 h whereupon it was filtered. Recrystallisation from
toluene (ca. 15 cm3) afforded colourless crystals (0.71 g, 54%).
m.p. 235–238 ЊC (Found: C, 39.33; H, 5.13; N, 5.46. Calc. for
1
C9H14AlNSSe: C, 39.42; H, 5.15; N, 5.11%). H NMR (200
MHz, C6D6, 25 ЊC): δ 7.03 (10 H, m, C6H5) and 2.08 (s, NCH3).
Syntheses
[{Al(ì-Se)(SePh)(NMe3)}2]. A yellow solution of (SePh)2
(0.57 g, 1.83 mmol) in toluene (ca. 10 cm3) was added to a
colourless solution of [{AlH(µ-Se)(NMe3)}2] (0.61 g, 1.84
mmol) in toluene (ca. 30 cm3) at room temperature. Gas evolu-
tion was observed. The resulting colourless solution was
allowed to stir for 17 h whereupon it was filtered. Recrystallis-
ation from toluene (ca. 15 cm3) afforded colourless crystals (0.30
g, 26%). m.p. 211–213 ЊC (Found: C, 36.54; H, 5.06; N, 4.20.
Calc. for C18H28Al2N2Se4ؒ0.5C7H8: C, 37.52; H, 4.69; N,
4.07%). 1H NMR (200 MHz, C6D6, 25 ЊC): δ 8.10–8.05 (2 H, m,
C6H5), 7.04–6.93 (3 H, m, C6H5) and 2.04 (9 H, s, NCH3); 13C
NMR (50.3 MHz, C6D6, 25 ЊC): δ 134.0, 131.7, 129.4, 128.9,
125.8 (C6H5) and 47.3 (NCH3).
[Ga(TePh)3(NMe3)]. A red solution of (TePh)2 (0.60 g, 1.47
mmol) in diethyl ether (ca. 10 cm3) was slowly added to a stirred
solution of [GaH3(NMe3)] (0.13 g, 0.99 mmol) in diethyl ether
(ca. 20 cm3) at 25 ЊC. Slight gas evolution was observed upon
addition. The red mixture was stirred for 14 h whereupon it was
filtered and the solvent removed in vacuo. Recrystallisation
from diethyl ether (ca. 10 cm3) at 4 ЊC afforded yellow crystals
(0.72 g, 62%), m.p. decomp. > 101 ЊC (Found: C, 35.18; H, 3.66;
N, 1.78. Calc. for C21H24GaNTe3: C, 33.95; H, 3.26; N, 1.89%).
1H NMR (300 MHz, C6D6, 25 ЊC); δ 7.65 (6 H, m, OH of
C6H5), 6.83 (9 H, m, m- and p-H of C6H5) and 2.05 (9 H, s,
NCH3). 13C NMR (75.4 MHz, C6D6, 25 ЊC): δ 141.7, 137.8,
129.2, 108.3 (C6H5) 47.9 (NCH3).
[Ga(SeEt)3(NMe3)]. Orange (SeEt)2 (0.38 cm3, 1.76 mmol)
was syringed dropwise into a colourless solution of [GaH3-
[{AlH(ì-Se)(tmen)}∞]. The compound tmen (0.30 cm3, 1.96
mmol) was added dropwise to a colourless solution of [{AlH-
J. Chem. Soc., Dalton Trans., 1998, Pages 2547–2556
2553

Table 1 Crystal data and details of the data collection and structure refinement for [Al(SePh)3(NMe3)] 1, [Ga(TePh)3(NMe3)] 2, [Ga(TePh)3{P(C6H11)3}] 3, trans-[{Al(µ-Se)(SPh)(NMe3)}2] 4, trans-[{Al(µ-
Se)(SePh)(NMe3)}2] 5, trans-[{Al(µ-Se)[N(SiMe3)2](NMe3)}2] 6 and trans-[{Ga(Cl)(µ-Se)[P(C6H11)3]}2] 7*
1
2
3
4
5ؒ2C6H5Me
6
7ؒC6H5Me
Formula
M
C21H24AlNSe3
554.3
C21H24GaNTe3
743.0
C36H48GaPTe3
964.3
C18H28Al2N2S2Se2
548.5
C32H44Al2N2Se4
826.5
C18H54Al2N4Se2Si2
650.9
C43H74Cl2Ga2P2Se2
1021.3
Crystal system
Space group
a/Å
b/Å
c/Å
α/Њ
β/Њ
Monoclinic
Cc (no. 9)
10.966(2)
18.973(4)
11.300(8)
Monoclinic
P21/c (no. 14)
7.317(2)
13.948(5)
24.215(6)
Monoclinic
P21/c (no. 14)
9.928(3)
33.933(9)
12.655(2)
Monoclinic
P21/c (no. 14)
9.507(4)
10.596(4)
12.111(4)
Monoclinic
C2/m (no.12)
16.37(1)
10.461(9)
10.447(8)
Triclinic
P1 (no. 2)
Triclinic
P1 (no. 2)
¯
¯
12.458(1)
9.120(1)
8.543(1)
66.23(1)
72.87(1)
85.73(1)
847.8(2)
0.074 × 0.25 × 0.48
1.275
1
23.9
1.19, 1.75
65
14.891(3)
9.761(5)
8.562(2)
76.04(3)
84.07(2)
84.15(3)
1197.4(8)
0.08 × 0.18 × 0.30
1.416
1
28.5
1.25, 2.03
50
99.02(4)
91.06(2)
120.88(2)
100.29(3)
93.38(7)
γ/Њ
U/Å3
2322(2)
0.48 × 0.40 × 0.21
1.585
4
48.0
2.29, 4.07
50
2471(1)
0.45 × 0.37 × 0.24
1.997
4
45.9
2.28, 3.01
55
3659(2)
0.32 × 0.13 × 0.34
1.750
4
31.6
1.59, 2.32
50
1200.3(7)
0.12 × 0.60 × 0.40
1.517
2
33.3
1.47, 2.54
50
1786(2)
0.25 × 0.20 × 0.15
1.536
2
41.2
—
Crystal size/mm
Dc/g cmϪ3
Z
µ/cmϪ1
A*(min,max)
2θmax/Њ
45
No. unique reflections
No. observed data
R
RЈ
2042
1165
0.064
0.060
5665
3705
0.031
0.032
6328
3714
0.061
0.064
2106
1477
0.036
0.038
1264
748
0.065
0.117
5051
2941
0.042
0.045
4220
1858
0.059
0.054
* Data collected at ca. 297 K on a ENRAF-Nonius CAD 4 or at ca. 100 K on a Nicolet R3m/V diffractometer (compound 5 only); graphite-monochromated Mo-Kα radiation (λ = 0.71073 Å); statistical weights;
anisotropic thermal parameters refined for all non-hydrogen atoms, C(1) for 1 excepted, for absorption corrected ‘observed’ data, with I > 3σ(I) [2σ(I), 5]; hydrogen atoms were inserted at calculated positions and
constrained, with isotropic thermal parameters at 1.25Ueq of the attached carbon; R, RЈ for other hand for 1 0.067, 0.064; for 5 and 7 toluene molecules are disordered about twofold rotation axes and inversion centres
respectively.

View Article Online
(µ-Se)(NMe3)}2] (0.65 g, 1.96 mmol) in toluene (ca. 60 cm3) at
room temperature. A white precipitate started forming upon
addition. The cloudy reaction mixture was allowed to stir for 12
h at room temperature whereupon it was filtered leaving a white
insoluble product (0.53 g, 82%). m.p. > 350 ЊC (Found: C,
21.89; H, 5.21; N, 8.27. Calc. for C3H9AlNSe: C, 21.83; H, 5.50;
13 W. Uhl, U. Schütz, W. Hiller and M. Heckel, Organometallics, 1995,
14, 1073.
14 W. Uhl, R. Graupner and H. Reuter, J. Organomet. Chem., 1996, 523,
227.
15 W. Uhl, R. Gerding, I. Hahn, S. Pohl, W. Saak and H. Reuter,
Polyhedron, 1996, 15, 3987.
16 H. Rahbarnoohi, R. L. Wells, L. M. Liable-Sands, G. P. A. Yap and
A. L. Rheingold, Organometallics, 1997, 16, 3959.
17 M. G. Gardiner, C. L. Raston and V.-A. Tolhurst, J. Chem. Soc.,
Chem. Commun., 1995, 2501.
18 P. D. Godfrey, C. L. Raston, B. W. Skelton, V.-A. Tolhurst and A. H.
White, Chem. Commun., 1997, 2235.
19 M. B. Power, J. W. Ziller, A. N. Tyler and A. R. Barron,
Organometallics, 1992, 11, 1055.
20 M. A. Banks, O. T. Beachley, H. J. Gysling and H. R. Luss,
Organometallics, 1990, 9, 1979.
21 A. H. Cowley, R. A. Jones, P. R. Harris, D. A. Atwood,
L. Contreras and C. J. Burek, Angew. Chem., Int. Ed. Engl., 1991, 30,
1143.
22 S. Schulz, H. W. Roesky, H. J. Koch, G. M. Sheldrick, D. Stalke and
A. Kuhn, Angew. Chem., Int. Ed. Engl., 1993, 32, 1729.
23 S. Schulz, E. G. Gillan, J. L. Ross, L. M. Rodgers, R. D. Rodgers
and A. R. Barron, Organometallics, 1996, 15, 4880.
24 C. J. Harlan, E. G. Gillian, S. G. Bott and A. R. Barron,
Organometallics, 1996, 15, 5479.
N, 8.49%). ν(Al᎐H) 1786 cmϪ1
.
[{Al(ì-Se)[N(SiMe3)2](NMe3)}2]. A solution of NH(SiMe3)2
(0.45 g, 2.8 mmol) in toluene (ca. 10 cm3) was added to a colour-
less solution of [{AlH(µ-Se)(NMe3)}2] (0.46 g, 1.4 mmol) in
toluene (ca. 30 cm3) at room temperature. Gas evolution was
observed. The resulting colourless solution was allowed to stir
for 11 h whereupon it was filtered. Recrystallisation from
toluene (ca. 10 cm3) afforded colourless needles (0.36 g, 40%),
m.p. > 300 ЊC (Found: C, 34.97; H, 8.23; N, 8.71. Calc. for
1
C9H27AlN2SeSi: C, 36.35; H, 9.15; N, 9.42%). H NMR (200
MHz, C6D6, 25 ЊC): δ 2.25 (18 H, s, NMe) and 0.52 (36 H, s,
SiCH3). 13C NMR (50.3 MHz, C6D6, 25 ЊC): δ 46.5 (NCH3) and
2.1 (SiCH3).
[{Al(ì-Se)(NC5H3NSiMe3-2-Me-6)}2].
A solution of 6-
25 M. B. Power, J. W. Ziller and A. R. Barron, Organometallics, 1992,
11, 2783.
26 R. J. Wehmschulte and P. P. Power, J. Am. Chem. Soc., 1997, 119,
9566.
methyl-2-trimethylsilylaminopyridine (0.28 g, 1.55 mmol) in
toluene (ca. 5 cm3) was added dropwise to a solution of
[{AlH(µ-Se)(NMe3)}2] (0.26 g, 0.78 mmol) in toluene (ca. 30
cm3) at room temperature. Gas evolution was observed and
a white precipitate gradually formed. The resulting cloudy
reaction mixture was allowed to stir for 16 h whereupon the
colourless solution was filtered and the toluene removed in
vacuo affording a white powder which was washed with hexane
and dried (0.27 g, 49%) m.p. > 160 ЊC (decomp.) (Found:
C, 37.50; H, 5.45; N, 9.56. Calc. for C15H9AlN2SeSi: C, 37.90;
27 J. L. Atwood and S. K. Seale, J. Organomet. Chem., 1976, 114,
107.
28 H. v. Dahlen and K. Dehnicke, Chem. Ber., 1977, 110, 383.
29 C. J. Warren, D. M. Ho, R. C. Haushalter and A. B. Bocarsly,
J. Chem. Soc., Chem. Commun., 1994, 361.
30 C. L. Raston, J. Organomet. Chem., 1994, 475, 15; C. Jones,
G. A. Koutsantonis and C. L. Raston, Polyhedron, 1993, 12,
1829.
31 A. R. Barron, J. Chem. Soc., Dalton Trans., 1988, 3047.
32 J. L. Atwood, K. W. Butz, M. G. Gardiner, C. Jones, G. A.
Koutsantonis, C. L. Raston and K. D. Robinson, Inorg. Chem.,
1993, 3482.
1
H, 5.30; N, 9.82%). H NMR (major component) (200 MHz,
C6D6, 25 ЊC): δ 7.05–5.70 (m, 3 H, C6H5N), 2.03 (s, 3 H, CH3)
and 0.30 (s, 9 H, SiCH3).
33 E. Hanecker, H. Nöth and U. Wietelmann, Chem. Ber., 1986, 119,
1904.
Crystallography
34 G. Yagupsky, W. Mowart, A. Shortland and G. Wilkinson, Chem.
Commun., 1970, 1369.
35 H. Horn, F. Rudolph, R. Ahlrichs and K. Merzweiler, Z.
Naturforsch., Teil B, 1992, 47, 1.
36 R. Kumar, H. E. Mabrouk and D. G. Tuck, J. Chem. Soc., Dalton
Trans., 1988, 1045.
37 T. A. Annan, R. Kumar, H. E. Marbrouk and D. G. Tuck,
Polyhedron, 1989, 7, 865.
Suitable crystals were sealed in capillaries under argon. Crystal-
lographic data are summarised in Table 1. Refinements were
carried out using XTAL,66 SHELXS and SHELXL67 program
systems.
CCDC reference number 186/1026.
See http://www.rsc.org/suppdata/dt/1998/2547/ for crystallo-
graphic files in .cif format.
38 V. A. Schneider and G. Gattow, Z. Anorg. Allg. Chem., 1954, 277,
49.
39 M. Julien-Pouzol, S. Jaulmes and F. Alapini, Acta Crystallogr., Sect
B, 1977, 33, 2270.
40 S. Schulz, M. Andruh, T. Pape, T. Heinze, H. W. Roesky,
L. Haming, A. Kuhn and R. Herbst-Irmer, Organometallics, 1994,
13, 4004.
41 D. F. Grant, R. C. G. Killean and J. L. Lawrence, Acta Crystallogr.,
Sect. B, 1969, 25, 377.
Acknowledgements
We thank the Australian Research Council for funds in support
of this work.
42 C. D. Whitt, L. M. Parker and J. L. Atwood, J. Organomet. Chem.,
1971, 32, 291.
43 H. Schumann, T. D. Seuss, O. Just, R. Weimann and H. Hemling,
J. Organomet. Chem., 1994, 479, 171.
References
1 T. Inoue, N. Kambe, I. Ryu and N. Sonoda, J. Org. Chem., 1994, 59,
8209.
2 T. Inoue, T. Takeda, N. Kambe, A. Ogawa, I. Ryu and N. Sonoda,
J. Org. Chem., 1994, 59, 5824.
3 T. Inoue, T. Takeda, N. Kambe, A. Ogawa, I. Ryu and N. Sonoda,
Organometallics, 1994, 13, 4543.
44 H. S. Isom, A. H. Cowley, A. Decken, F. Sissingh, S. Corbelin and
R. J. Lagow, Organometallics, 1995, 14, 2400.
45 J. L. Atwood, S. G. Bott, F. M. Elms, C. Jones and C. L. Raston,
Inorg. Chem., 1991, 30, 3792.
4 Brown and Davidson, J. Am. Chem. Soc., 1942, 64, 316.
5 G. E. Coates, J. Chem. Soc., 1951, 2003.
6 K. Ruhlandt-Senge and P. P. Power, Inorg. Chem., 1991, 30, 3683.
7 S. P. Wuller, A. L. P. Seligson and G. Arnold, Inorg. Chem., 1995, 34,
4854.
46 J. L. Atwood, K. D. Robinson, F. R. Bennett, F. M. Elms, G. A.
Koutsantonis, C. L. Raston and D. J. Young, Inorg. Chem., 1992, 31,
2673.
47 F. M. Elms, G. A. Koutsantonis and C. L. Raston, J. Chem. Soc.,
Chem. Commun., 1995, 1669.
8 R. Kumar, D. G. Dick, S. U. Ghazi, M. Taghiof, M. J. Heeg and
J. P. Oliver, Organometallics, 1995, 14, 1601.
9 M. G. Gardiner, C. L. Raston and V.-A. Tolhurst, J. Chem. Soc.,
Chem. Commun., 1995, 1457.
10 W. Uhl, M. Layh, G. Becker, K. W. Klinkhammer and
T. Hildenbrand, Chem. Ber., 1992, 125, 1547.
11 W. Uhl, A. Vester and W. Hiller, J. Organomet. Chem., 1993,
443, 9.
12 W. Uhl and U. Schütz, Z. Naturforsch., Teil B, 1994, 49, 931.
48 U. App and K. Merzweiler, Z. Anorg. Allg. Chem., 1997, 623,
478.
49 C. Jones, Ph.D. Thesis, Griffith University, 1992.
50 H. Roszinski, R. Dautel and W. Zeil, Z. Phys. Chem. Neue Folge,
1963, 36, 26.
51 K. Ruhlandt-Senge and P. P. Power, Inorg. Chem., 1991, 30,
2633.
52 C. Jones, F. Lee, G. A. Koutsantonis, M. G. Gardiner and C. L.
Raston, J. Chem. Soc., Dalton Trans., 1996, 829.
J. Chem. Soc., Dalton Trans., 1998, Pages 2547–2556
2555

View Article Online
53 V. S. J. De Mel, R. Kumar and J. P. Oliver, Organometallics, 1990, 9,
62 C. A. Grob, A. Kaiser and E. Renk, Chem. Ind., 1957, 598.
1303.
63 F. R. Bennett, F. M. Elms, M. G. Gardiner, G. A. Koutsantonis,
C. L. Raston and N. K. Roberts, Organometallics, 1992, 11,
1457.
64 L. M. Engelhardt, G. E. Jacobsen, P. C. Junk, C. L. Raston, B. W.
Skelton and A. H. White, J. Chem. Soc., Dalton Trans., 1988,
1011.
54 C. L. Raston, B. W. Skelton, V.-A. Tolhurst and A. H. White,
Polyhedron, 1998, 17, 935.
55 T. Her, C. Chang, S. Peng and Y. Wang, Inorg. Chem., 1994, 33,
99.
56 M. G. Gardiner, G. A. Koutsantonis, S. M. Lawrence, F. Lee and
C. L. Raston, Chem. Ber., 1996, 129, 545.
57 J. J. Byers, W. T. Pennington and G. H. Robinson, Polyhedron, 1990,
65 J. A. Gladysz, J. L. Hornby and J. E. Garbe, J. Org. Chem., 1978, 43,
1204.
9, 2205.
66 S. R. Hall, H. D. Flack and J. M. Stewart, The XTAL 3.2 Reference
Manual, Universities of Western Australia, Geneva and Maryland,
1992.
67 G. M. Sheldrick, SHELXS 86 and SHELXL 93, Programs for
crystal structure solution and refinement, University of Göttingen,
1986 and 1993.
58 K. von Ouzounis, H. Riffel, H. Hess, U. Kohler and J. Weidlein,
Z. Anorg. Allg. Chem., 1983, 504, 67.
59 G. M. Sheldrick and W. S. Sheldrick, J. Chem. Soc. A, 1969,
2279.
60 R. Grüning and J. L. Atwood, J. Organomet. Chem., 1977, 137,
101.
61 J. K. Ruff and M. F. Hawthorne, J. Am. Chem. Soc., 1960, 82,
Received 23rd March; 1998; Paper 8/02243G
2141.
2556
J. Chem. Soc., Dalton Trans., 1998, Pages 2547–2556