Covalent 3- and 2-dimensional titanium-quinone networks

Full text of DOI:10.1021/ja971658o

8742
J. Am. Chem. Soc. 1997, 119, 8742-8743
Covalent 3- and 2-Dimensional Titanium-Quinone
Networks
Thomas P. Vaid, Emil B. Lobkovsky, and
Peter T. Wolczanski*
Cornell UniVersity, Baker Laboratory
Department of Chemistry, Ithaca, New York 14853
ReceiVed May 21, 1997
Extended 3- and 2-dimensional networks derived from
transition or main group metals combined with ligands pos-
sessing multiple binding sites comprise a forefront area of
research in solid state chemistry.1-3 Networks have been
constructed from 4,4′-bipyridine,4-7 pyrazines,6-10 pyrimidine,11
cyanide,3,12-14 azide,15 and larger, more elaborate organic
spacers.3,16-20 For example, tetra(p-cyanophenyl)methane com-
bines with Cu+ to form a predicted diamondoid network,3 and
20
1,3,5-(NtCCtC)3C6H3 spans Ag+ in extending a ThSi2
structural motif to the metal-organic realm. The critical fusion
of metal and organic spacer is usually accomplished through a
framework of dative bonds; consequently, degradation pathways
based on ligand dissociation or solvolysis may be present.
Strong, covalent21 titanium/quinone linkages chosen to encour-
age intermetallic communication (i.e., TiIV-OC6H4O-TiIV
T
TiIIIrOdCC4H4CdOfTiIII) are the crucial connections for the
dense networks reported herein.
Using a modified procedure of Burch,22 Ti(iOPr)4 was treated
with 2.58 equiv of hydroquinone in THF to yield an amorphous
(XRD), red-orange powder upon drying (eq 1). After the
Figure 1. (a) Bioctahedral dititanium building block of [{(OC6H4O)-
(OC6H4OH)Ti}2(µ-OC6H4OH)2]n (2) with all bridges included (distances
in Å, angles in deg): O1-Ti-O3 ) 166.2(2); O1-Ti-O4A ) 76.4-
(2); O1-Ti-O5 ) 92.5(2); O1-Ti-O6 ) 85.5(2); O1A-Ti-O3 )
93.1(2); O1A-Ti-O4A ) 76.4(2); O1A-Ti-O5 ) 161.1(2); O1A-
Ti-O6A ) 89.4(2); O3-Ti-O4A ) 92.2(2); O3-Ti-O5 ) 99.8(2);
O3-Ti-O6A ) 98.0(2); O4A-Ti-O5 ) 89.3(2); O4A-Ti-O6A )
163.0(2); O5-Ti-O6 ) 102.3(2). (b) Distorted octahedral building
block of [cis-Ti(OC6H4O)2py2]n (3a) with all bridges included: O1-
Ti-O3 ) 94.3(2); O1-Ti-N1 ) 82.9(2); O2-Ti-O3 ) 95.8(2); O2-
Ti-N1 ) 85.2(2); N1-Ti-O3 ) 94.3; N1-Ti-O3A ) 170.6(2).
Ti(iOPr)4 + 2.58HOC6H4OH THF, 25 °C8
1/n[Ti(OC6H4O)a(OC6H4OH)3.34-1.83a(OiPr)0.66-0.17a(THF)0.2 n
]
+
1 (0.91 e a e 1.82)
(3.34 + 0.17a)HOiPr (1)
100 °C, 1-4 d
1
8
Et2O or DME
∼1 M HOC6H4OH
[{(OC6H4O)(OC6H4OH)Ti}2(µ-OC6H4OH)2]n
(2)
(3)
2
1
100 °C, 1-4 d8 [cis-Ti(OC6H4O)2py2]n
d. Hydroquinone presumably deaggregates 1, leading to spar-
ingly soluble mono- or dititanium fragments that can be
reconstituted into distinct microcrystalline networks.
py, 1.82 M
3a
HOC6H4OH
Single-crystal X-ray diffraction studies of materials derived
from Et2O (2, eq 2) and pyridine (3a, eq 3) revealed dramatic
solvent-dependent changes in the dimensionality and connectiv-
ity of the metal-organic network. The crystal size (20 × 20
× 60 µm) of [{(OC6H4O)(OC6H4OH)Ti}2(µ-OC6H4OH)2]n (2)
required data aquisition via a synchrotron source (CHESS).23
1
powder was quenched with D2O/DCl, H NMR spectroscopic
analysis of the DOC6H4OD/DOiPr/THF ratio revealed the
empirical formula indicated (1). Addition of HOC6H4OH to 1
in various solvents (∼1 M) enabled a conversion to burgundy,
microcrystalline compounds upon thermolysis at 100 °C for 1-4
(1) Fagan, P. J.; Ward, M. D. Sci. Am. 1992, 267, 48-54.
(2) (a) Zaworotko, M. J. Chem. Soc. ReV. 1994, 23, 283-288. (b) Robson,
R.; Abrahams, B. F.; Batten, S. R.; Gable, R. W.; Hoskins, B. F.; Liu, J.
Supramolecular Architecture; American Chemical Society: Washington,
DC, 1992; Chapter 19.
(3) Hoskins, B. F.; Robson, R. J. Am. Chem. Soc. 1990, 112, 1546-1554.
(4) Fujita, M.; Kwon, Y. J.; Washizu, S.; Ogura, K. J. Am. Chem. Soc.
1994, 116, 1151-1152.
(5) Yaghi, O. M.; Li, G. Angew. Chem., Int. Ed. Engl. 1995, 34, 207-
209.
(14) (a) Yu¨nlu¨, K.; Ho¨ck, N.; Fischer, R. D. Angew. Chem., Int. Ed.
Engl. 1985, 24, 879-881. (b) Adam, M.; Brimah, A. K.; Fischer, R. D.;
Xing-Fu, L. Inorg. Chem. 1990, 29, 1595-1597. (c) Behrens, U.; Brimah,
A. K.; Soliman, T. M.; Fischer, R. D.; Apperley, D. C.; Davies, N. A.;
Harris, R. K. Organometallics 1992, 11, 1718-1726.
(15) Mautner, F. A.; Cortes, R.; Lezama, L.; Rojo, T. Angew. Chem.,
Int. Ed. Engl. 1996, 35, 78-80.
(16) (a) Batten, S. R.; Hoskins, B. F.; Robson, R. Angew. Chem., Int.
Ed. Engl. 1997, 36, 636-637. (b) Batten, S. R.; Hoskins, B. F.; Robson,
R. J. Chem. Soc., Chem. Commun. 1991, 445-447. (c) Konnert, J.; Britton,
D. Inorg. Chem. 1966, 5, 1193-1196.
(6) MacGillivray, L. R.; Subramanian, S.; Zaworotko, J. J. Chem. Soc.,
Chem. Comm. 1994, 1325-1326.
(7) Soma, T.; Yuge, H.; Iwamoto, T. Angew. Chem., Int. Ed. Engl. 1994,
33, 1665-1666.
(17) (a) Abrahams, B. F.; Hoskins, B. F.; Mitchail, D. M.; Robson, R.
Nature 1994, 369, 727-729. (b) Abrahams, B. F.; Batten, S. R.; Hamit,
H.; Hoskins, B. F.; Robson, R. Angew. Chem., Int. Ed. Engl. 1996, 35,
1690-1692.
(8) Carlucci, L.; Ciani, G.; Proserpio, D. M.; Sironi, A. J. Am. Chem.
Soc. 1995, 117, 4562-4569.
(9) Otieno, T.; Rettig, S. J.; Thompson, R. C.; Trotter, J. Inorg. Chem.
1993, 32, 1607-1611.
(18) (a) Carlucci, L.; Ciani, G.; Proserpio, D. M.; Sironi, A. Inorg. Chem.
1997, 36, 1736-1737. (b) Carlucci, L.; Ciani, G.; Proserpio, D. M.; Sironi,
A. Angew. Chem., Int. Ed. Engl. 1996, 35, 1088-1090.
(10) Real, J. A.; DeMunno, G.; Munoz, M. C.; Julve, M. Inorg. Chem.
1991, 30, 2701-2704.
(19) Kawata, S.; Kitagawa, S.; Kondo, M.; Furuchi, I.; Munakata, M.
Angew. Chem., Int. Ed. Engl. 1994, 33, 1759-1761.
(11) Keller, S. W. Angew. Chem., Int. Ed. Engl. 1997, 36, 247-248.
(12) Entley, W. R.; Girolami, G. S. Science 1995, 268, 397-400.
(13) (a) Gable, R. W.; Hoskins, B. F.; Robson, R. J. Chem. Soc., Chem.
Commun. 1990, 762-763. (b) Abrahams, B. F.; Hoskins, B. F.; Liu, J.;
Robson, R. J. Am. Chem. Soc. 1991, 113, 3045-3051.
(20) Gardner, G. B.; Kiang, Y.-H.; Lee, S.; Asgaonkar, A.; Vendataraman,
D. J. Am. Chem. Soc. 1996, 118, 6946-6953.
(21) Haaland, A. Angew. Chem., Int. Ed. Engl. 1989, 28, 992-1007.
(22) Burch, R. R. Chem. Mater. 1990, 2, 633-635.
S0002-7863(97)01658-2 CCC: $14.00 © 1997 American Chemical Society

Communications to the Editor
J. Am. Chem. Soc., Vol. 119, No. 37, 1997 8743
Figure 3. Stacking of the 2-D, pleated sheet of [cis-Ti(OC6H4O)2-
py2]n (3a).
C6 ) 143.3(6)°, Ti-O2-C9 ) 161.0(5)°, d(Ti-O1) ) 1.915-
(6) Å, d(Ti-O2) ) 1.875(6) Å) connect distorted octahedral
titanium centers (Figure 1b) in one dimension, while a zigzag
chain of cis-1,4-diphenoxides ( O3-Ti-O3A ) 103.3(3)°,
Ti-O3-C12 ) 137.4(4)°, d(Ti-O3) ) 1.883(4) Å) estab-
lishes the second (Figure 3). cis-Pyridines (d(Ti-N) ) 2.316-
(6) Å,N1-Ti-N1A ) 84.9(3)°) alternate with the arenes of
the zigzag cis-1,4-diphenoxide chain in order to efficiently pack
the sheets together, but their respective π-systems do not stack.
The triclinic unit cell of 3b28 can accommodate the [Ti(OC6H4O)2-
py2‚py]n formula unit (Fcalcd ) 1.32 g/cm3) suggested from
quenching studies. Thermolysis of 3b (1.82 M HOC6H4OH,
pyridine) ultimately afforded 3a, which did not revert to 3b
under a variety of conditions.
The diverse structures of [(OC6H4O)2(OC6H4OH)2Ti2(µ-
OC6H4OH)2]n (2) and [cis-Ti(O-C6H4O)2py2] (3a) and the other,
distinct derivatives derived from THF, CH3CN, EtCN,29 and
various hydroquinones portend a rich structural chemistry for
these covalently linked, robust, metal-organic networks. Ef-
forts are currently being directed toward imparting properties
to these dense, hybrid30,31 solids: (1) alkalai metal doping of 2
to afford ion conductivity or reduced titanium centers for
conductivity; (2) intercalation chemistry of 3a,b; and (3)
synthesis of d1 vanadium analogues and vanadium-doped
networks for electronic properties.
Figure 2. (a) One of the two nets showing the axial (O4, O6) to
equatorial (O3, O5) connectivity of [{(OC6H4O)(OC6H4OH)Ti}2(µ-
OC6H4OH)2]n (2); the µ-OC6H4OH bridges have been removed for
clarity. (b) The 4-hydroxyphenoxide (O3, O4) net of 2; the 1,4-
diphenoxide (O5, O6) net is similar.
Its 3-dimensional network is roughly derived from a body-
centered arrangement of bioctahedral dititanium building blocks
(Figure 1a, cf., [(PhO)3(PhOH)Ti]2(µ-OPh)2,24 [(PhO)Cl2Ti]2-
(µ-OPh)2)25 connected via 1,4-diphenoxide (O5, O6) and
4-hydroxyphenoxide (O3, O4) ligands, while the 4-hydroxyphe-
noxide bridges of each dimer fill void space. In Figure 2a, axial
1,4-diphenoxide (d(Ti-O6) ) 1.923(3) Å, Ti-O6-C16 )
129.3(3)°) and 4-hydroxyphenoxide (d(Ti-O4) ) 2.207(3) Å,
Ti-O4-C10 ) 125.9(3)°) ligands that hydrogen bond26 form
one planar net by linking via the equatorial sites (d(Ti-O5) )
1.794(4) Å, Ti-O5-C13 )164.1(3)°; (d(Ti-O3) ) 1.782-
(3) Å, Ti-O3-C7 ) 173.0(3)°) of adjacent Ti2(µ-OC6H4-
OH)2 units. In another view (Figure 2b), the planar net derived
solely from the 4-hydroxyphenoxide (O3eq, O4ax) is constructed,
and the bridging 4-hydroxyphenoxides (d(Ti-O1) ) 2.047(3),
2.042(3) Å; Ti-O1-TiA ) 106.5(2)°; O1-Ti-O1A ) 81.5-
(2)°) are shown as filling the void space in this dense network.
A relatively high concentration of HOC6H4OH in pyridine
(1.82 M) converted 1 to red crystals (<30 µm) of 3a (>98%,
eq 3), while lower concentrations (0.55 M) afforded green/black
3b in >95% yield. Synchrotron data aquisition and structure
solution revealed a 2-dimensional, pleated sheet structure for
[cis-Ti(OC6H4O)2py2]n (3a).27 A relatively linear strand of
trans-1,4-diphenoxides ( O1-Ti-O2 ) 163.7(3)°, Ti-O1-
Acknowledgment. We gratefully acknowledge contributions from
the National Science Foundation (CHE-9528914, Inorganic Materials
Traineeship to T.P.V. (DMR-9256824), Center for High Energy
Synchrotron Studies (CHESS), Materials Science Center) and Cornell
University.
Supporting Information Available: X-ray structural data pertain-
ing to [(OC6H4O)2(µ-1,4-OC6H4-OH)2Ti2(µ-OC6H4OH)2]n (2) and [cis-
(OC6H4O)2Ti(py)2]n (3a) and a summary of crystallographic parameters,
atomic coordinates, bond distances and angles, and anisotropic thermal
parameters (12 pages). See any current masthead page for ordering
and Internet access instructions.
JA971658O
(27) For 3a (30 × 30 × 30 µm): empirical formula, C22H18N2O4Ti; fw,
420.27; T ) 293(2) K; λ ) 0.9140 Å; orthorhombic, Pnma; a ) 15.631(3)
Å, b ) 14.017(3) Å, c ) 9.063(2) Å; Z ) 4; V ) 1985.7(7) Å3; Fcalcd
)
1.406 g/cm3; abs. coeff., 0.462 mm-1; 1318 reflections; GOF on F2, 1.224;
R1 ) 0.0858, wR2 ) 0.2338; calcd and exptl powder XRD matched.
(28) For 3b (2-4 µm, powder XRD): a ) 8.717(2) Å, b ) 8.803(2) Å,
c ) 9.016(2) Å, R ) 82.83(2)°, â ) 75.36(2)°, γ ) 71.09(2)°; V ) 632.6 Å3.
(29) For a “solvent” dependent lattice, see: Abrahams, B. F.; Hardy,
M. J.; Hoskins, B. F.; Robson, R.; Williams, G. A. J. Am. Chem. Soc. 1992,
114, 10641-10643.
(23) For 2: empirical formula, C18H14O6Ti; fw, 374.19; T ) 110(2) K;
λ ) 0.980 00 Å; monoclinic, P21/n; a ) 9.624(2) Å, b ) 11.283(2) Å, c )
14.916(3) Å; â ) 90.47(3)°; Z ) 4; V ) 1619.6(5) Å3; Fcalcd ) 1.535 g/cm3;
abs. coeff., 0.561 mm-1; 1451 reflections; GOF on F2, 1.061; R1 ) 0.0751,
wR2 ) 0.2280; calcd and exptl powder XRD matched.
(24) (a) Svetich, G. W.; Voge, A. A. J. Chem. Soc., Chem. Commun.
1971, 676-677. (b) Svetich, G. W.; Voge, A. A. Acta Crystallogr. 1972,
B28, 1760-1767.
(25) Watenpaugh, K.; Caughlan, C. N. Inorg. Chem. 1966, 5, 1782-1786.
(26) Vaarstra, B. A.; Huffman, J. C.; Gradeff, P. S.; Hubert-Pfalzgraf,
L. G.; Daran, J.-C.; Parraud, S.; Yunlu, K.; Caulton, K. G. Inorg. Chem.
1990, 29, 3126-3131.
(30) For related organic species, see: Desiraju, G. R. Angew. Chem.,
Int. Ed. Engl. 1995, 34, 2311-2327.
(31) For related inorganic species, see: (a) Mu¨ller, A.; Reuter, H.;
Dillinger, S. Angew. Chem., Int. Ed. Engl. 1995, 34, 2328-2361. (b)
Bonavia, G.; Haushalter, R. C.; O’Connor, C. J.; Zubieta, J. Inorg. Chem.
1996, 35, 5603-5612.