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Galloxane and Alumoxane Hydroxides [Ga12tBu12(3-O)8(-O)2(-OH)4] and [Al6tBu6(3-O)4(-OH)4].

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[8] E . M. Flanigen, B. M. Lok, R. L. Patton, S. T. Wilson in New' Derelopmenfs in
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Chem. lid. Ed. Engl. 1994, 33, 2335.
[i 11 K. Maeda, J. Akimoto, Y. Kiyozumi, F. Mizukami, J. Clwm. Soc. Chem. Commun. in press.
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[14] M. Sghydr. .I.Durdnd, L. Cot, M. Rafig, Acta Crystallogr. Sect. C 1991. 47,
[IS] R. E Morris. M. P. Attfield, A. K. Cheetham, Acta Crjstalfogr. Serf. C 1994,
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[I71 M. P Attfield, R. E. Morris, A. K . Cheetham, Acta Crystallogr. Secr. C 1994,
50, 98 1
[18] C. Y. Ortiz-Avh, P. J. Squdttrito. M. Shieh, A. Clearfield, Inorg. Cliem. 1989,
28, 2608.
1191 W. M . Meier. D H. Olson, Atlas o f z e o l i t e Strurtirre Types, 3rd ed., Butterworth-Heinemann. London, 1992.
[20] D. W. Areck, Zcolife Molecular SievrJ, Wiley, New York, 1974, p. 636.
[21] G. M Sheldrick, A c f u Crysrullogr. Sect. A 1990, 46, 467.
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[24l Y. L. Page. J. D. H. Donnay, G. Donnay, Acra CrystaNogr. Sect. A 1984, 40,
the formula unit. While the Et,O molecules of solvation are
disordered, the 0 . . 0 distances are within the range expected
for weak hydrogen bonding interaction. The molecular structure of 1 is shown in Figure 1. Each of the gallium atoms and
bridging 0 atoms (Ga-0-Ga) lie on a mirror plane. The cage
structure consists of twelve fused six-membered rings. Each gallium atom is coordinated to one carbon and three oxygens,
while there are two types of oxygen atom sites; six oxygens
bridging two galliums [O(l)], and eight oxygens capping three
galliums [0(2)]. However, the structure may also be considered
to consist of an 0x0-cube [0(2)], with each face capped by a
[tBuGa(p-X)GatBu] unit, X = 0 or OH.
Galloxane and Alumoxane Hydroxides:
[GaI z I z(rC3-o),(cC-o),(cC-oH)41
and [Al,tBU,(rCc3-o),(rC-oH)4]**
Fig. 1 . Molecular structure of 1. The methyl groups have been omitted for clarity.
The bridging oxygen atom, O(1), exists as a 40: 60 disorder of an 0 x 0 and a hydroxo
ligand. Selected bond lengths [A] and angles ["I: Ga(1)-O(1) 1.911(5), Ga(1)-0(2)
1.878(i), Ga(i)-C(Il) i.98( 1); 0(1)-Ga(l)-0(2) 98.4(2), O(2)-Ga( 1)-O(2a)
106.7(2), O(1)-Ga(l)-C(11) 114.6(5), 0(2)-Ga( 1)-C(1 1 ) 117.6(2), Ga( 1)-O(1)Ga( la) 129.1(1), Ga( 1)-0(2)-Ga(la) 119.6(I ) .
Christopher C. Landry, C . Jeff Harlan, Simon G. Bott,
and Andrew R. Barron*
In contrast to the extensive oxide and oxide-hydroxide chemistry observed for aluminum and indium,"] there are relatively
few studies of the analogous chemistry of gallium. A recent
'IGa NMR spectral study has indicated the formation of the
unstable cationic cluster, [Ga,,04(OH),4(H,0),,]7+,
structure is proposed to be identical to that of the aluminum
Similarly, the first organogallium-oxo compound reported, [tBuGa(p3-O)19,was determined by mass spectrometry
and NMR spectroscopy to also be isostructural to its aluminum
analog.[31The first reported examples of apparent diversification between the chemistry of aluminum and gallium oxide and
oxide-hydroxide clusters was for the hexagallium compounds
[Ga,Mes,O,X,], Mes = mesityl, X = F,I4]OH'51 for which the
equivalent aluminum compounds did not exist. We now report
the structural characterization of the largest galloxane hydroxide isolated thus far, as well as the aluminum analog of
Oxidation of [tBu,Ga(Spy)] (H-Spy = 2-mercaptopyridine),@]
followed by atmospheric hydrolysis yields colorless crystals with
a composition corresponding to [Ga,,tBu,,O,,(OH),] (1). Single crystals of 1 suitable for X-ray structure analysis['] were
obtained from Et,O and four molecules of solvent are present in
Prof. Dr. A. R. Barron, C. C. Landry, Dr. C . J. Harlan
Department of Chemistry, Harvard University
12 Oxford Street, Cambridge, MA 02138 (USA)
Telefax: Int. code: (617)496-7402
Prof. Dr. S . G. Bott
Department of Chemistry, University of North Texas, Denton (USA)
This work was supported by the Office of Naval Research, Akzo Nobel, the
Welch Foundation, and the University of North Texas Research Office.
Angiw Ciiem. Int Ed. Engl. 1995, 34, No. 11
Based upon charge balance and ' H N M R spectroscopy the
actual formula of 1 is [Ga,,rBu,,(p3-O),(p-O),(p-OH)4].
the oxygen atoms bridging two galliums are a disorder of two
0x0 and four hydroxo ligands. In line with this, the Ga-O(1)
distances [1.91l(5) A] are a weighted average of the values expected for a gallium-oxide (1.87- 3.89 A) and a gallium-hydroxide (2.21 -2.45 A). The Ga-O(2) distance [1.878(1) A] is exactly
as expected for a gallium-oxide interaction. The higher esd's in
the Ga-O(1) bond lengths and the thermal parameters for 0(1),
as compared to 0(2), is consistent with the presence of a disorder, however, the high symmetry of the molecule precluded refinement of this disorder.
A similar disorder between 0x0 and hydroxo ligands is observed in the structure of [Al,tBu,(p,-O)4(p3-OH)4] (2),
(Fig. 2) .['I Compound 2, prepared from the hydrolysis of
[tBuAI(p3-O)], ,[*I is isostructural to [Ga,Mes,O,X,] (X = F,
OH). As with the gallium compounds, 2 can be described as an
octahedron of aluminum atoms, with each face capped by either
a p 3 - 0 or p3-OH moiety.['] An alternative description is that
compound 2 is a cube of oxygen atoms face-capped by six
AltBu units, and as such a structural relationship between
1 and 2 may be drawn. Like the gallium compounds,
the oxide and hydroxide sites in 2 are disordered. The
A1(1)-0(1) distance [1.900(8) A] is within the range ofvalues we
have previously reported for AI-OH [1.84- 1.90 A] interactions, while the A1(1)-0(2) distances [I .87(1)- 1.95(1) A] cover
the range for both A I L 0 [1.78-1.88& and AI-OH distances.l'ol This is obviously a result of the high symmetry of the
[AltBu], core.
VCH Verlag.~gesrllsciiaftm b H , 0-6945'1Weinheim. 1995
Oj70-0833,'95/1111-1201B l~l.Ofl+..?j:(I
Fig. 3. Polyhedral structure of 1. The methyl groups have been omitted for clarity.
Fig. 2. Molecular structure of 2. The hydrogen atoms have been omitted forclarity.
Both O(1) and O(2) exist as a 50:50 disorder of an 0x0 and a hydroxo ligand.
Selected bond lengths [A] and angles ["I: A1(1)-0(1) 1.900(8), AI(1)-0(2) 1.95(1),
A1(1)-0(2a) 1.88(1), A1(1)-0(2b) 3.87(1), AI(1)-C(1) 1.910(9); O(l)-AI(1)-0(2)
74.8(3). O(l)-Al(l)-O(2a) 74.4(3), O(l)-Al(l)-O(2b) 122.1(3), O(l)-AI(l)-C(l)
116.6(6), 0(2)-Al(l)-0(2a) 125.3(3), 0(2)-A1(1)-0(2b) 77.9(3). Al(1 )-O(1)-Al( 1a)
3 03.7(9). Al( 1)-0(2)-Al( l a ) 102.5(9).
A rational for the formation of 2 from [tBuAl(p3-O)], is the
addition of H,O to an A1-0 bond [Eq. (a)]. We have observed
a similar reaction during the formation of alumoxane carboxylates from the aluminum oxides [Eq. (b)] .["I
Given that several workers have postulated the existence of
five-coordinate aluminum in alumoxanes,['21 it is important to
note that compound 2 represents the first structural characterization of an alkylalumoxane in which the aluminum centers are
Finally, we note that 1 is unusual when compared to previous
group 13- 16 cluster compounds or solid-state phases, in that
while several chalcogenide cages are made entirely of six-membered cycles, this represents the first example of an oxygen
derivative with such a structure."' Thus, 1 consists of twelve
vertex-sharing tetrahedra (Fig. 3), while other alumoxanes,
galloxanes, and indoxanes consist of edge- as well as vertexsharing tetrahedra. Furthermore, 1 has a cavity of about
2.4 A in diameter in which the shortest centroid-cage distance
is to O(2) (1.3 A); sufficiently large to accommodate a variety
of different cations. In this regard 1 represents the first
example of a group 13- 16 cage in which inclusion may occur in
a manner analogous to that observed for vanadium phosphates." 31
VCH Verlagsgesell.~chaftmbH, 0-69451 Weinheim, 1995
Experirnen tal Procedure
1: A solution of [tBu,Ga(Spy)] (0.501 g. 1.71 mmol) in toluene (30 mL) was exposed
to a n atmosphere of dry oxygen, upon which a white precipitate formed from the
yellow solution. Filtration, followed by crystallization from Et,O in air allowed the
isolation of 1. Isolated yield: about 70%. ' H N M R (C,D,): 6 =1.30 (4 H, br, s;
OH), 1.06 [36 H, s; C(CH,),], 1.02 [72 H, s; C(CH,),]; IR (cm-'). i = 3400 (OH).
2: To a solution of [iBuAl(~c,-O)], (0.415 g. 0.691 mmol) in hexane (20 mL) was
added wet /i-lactone (0.056 g, 0.65 mmol). The reaction was stirred overnight at
room temperature. An insoluble white precipitate formed. Filtration and cooling of
the supernatant resulted in the crystallization of compound 2. Isolated yield: about
9%. ' H N M R (C,D,): d = 2.48 (4 H, s ; OH), 1.02 [54 H, s; C(CH,),]. IR (cm-'):
^v = 3424 (OH).
Received: December 27, 1994
Revised version: February 20, 1995 [Z7582IE]
German version: Angrw. Chem. 1995, 107, 1315-1317
Keywords: aluminum compounds cage compounds . coordination . gallium compounds
[l] For a review see, A. R. Barron, Comments Inorg. Chem. 1993, 14, 123.
[2] S. M. Bradley, R. A. Kydd, R. Yamdagni, .
Chem. SOC.Dalron Trans. 1990,
[3] M. 9. Power, J. W. Ziller, A. R. Barron, Organometaflics 1992, 1 1, 2783.
[4] 9. Neumuller, F. Gahlmann, Angew. Chem. 1993,105,1770; Angew'. Chem. Int.
Ed. Engl. 1993,32, 1701.
[5] J. Storre, T. Belgardt, D. Stalke, H. W. Roesky, Angew. Chem. 1994,106, 1365;
Angew. Chem. In/. Ed. Engl. 1994, 33, 1244.
[6] C. C. Landry, A. Hynes, I. Haiduc, A. R. Barron, Polyhedron in press.
[7] X-ray structure analysis of 1,4(Et,0) space group Pm%, a =15.972(1) A,
V = 4074.5(6) A3, pEalra
= 1.665 g ~ m - ~2(MoKm)
= 0.7107 A, T = 2 5 T ,
range of data = 2 < 28 < W , 560 unique reflections, 295 observed
( I> 60(i)),R = 0.0339, R, = 0.0412, data t o parameter ratio = 8.2. X-ray
structure analysis of 2 space group R3, a =30.611(1), c = 29.736(3)A,
= 1.094 gem-,, >.(MoKm)
= 0.7107 A, T = 25 "C,
V = 2899.6(5) A', pcalcd
range of data = 2 < 20 < 44", 1 1 22 unique reflections, 353 observed
( I > 4o(I)), R = 0.0756, R, = 0.0748, data t o parameter ratio = 6.4. Structure
solution was by SHELXT. Further details of the crystal structure investigation
may be obtined from the Director of the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge, CB2 lEZ(UK) on quoting the full journal
[8] M. R. Mason, J. M . Smith, S. G. Bott, A. R. Barron, J. Am. Chem. SOC.1993,
[9] Although unusual, trifurcated hydroxide groups have previously been structurally characterized for aluminum compounds. see A. W. Apblett, A. C. Warren, A. R. Barron, Chem. Mater. 1992, 4 , 167.
[lo] C. J. Harlan, M . R. Mason, A. R. Barron. Organometnfiics 1994, 13, 2957.
[ l l ] C. C. Landry, N. Pappe, M. R. Mason, A. W. Apblett. A. N. Tyler, A. N.
MacInnes, A. R. Barron, J. Muter. Chem. 1995, 5, 33.
[12] See, S. Pasynkiewicz, Polyhedron 1990, 9,429, and references therein.
[13] J. Salta, Q. Chen, Y. Chang, J. Zubieta, Angew. Chem. 1994, 106, 781; Angew.
Chem. I n f . Ed. EngI. 1994, 33, 757, and references therein.
0570-O833/95/l1//-1202$10.00f .25/0
Angen. Chem. Inr. Ed. Engl. 1995, 34, No. 11
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ga12tbu12, hydroxide, alumoxane, al6tbu6, galloxane
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