Controlled synthesis of a structurally characterized family of sterically constrained heterocyclic alkoxy-modified titanium alkoxides

Article abstract of DOI:10.1021/ic0618798

The reaction of [Ti(μ-ONep)(ONep)₃]₂ (ONep = OCH₂C(CH₃)₃) with a series of heterocyclic methanol derivatives [tetrahydrofurfuryl alcohol (H-OTHF), thiophene methanol (H-OTPM), or 2-pyridylcarbinol (H-OPy) - collectively termed H-OR*], led to the isolation of a novel family of OR*-substituted titanium alkoxide precursors. Independent of the initial stoichiometry for the H-OTHF reaction, a monosubstituted, dinuclear species was isolated as [(ONep)₃Ti- (μ_c-OTHF)]₂ (1). For 1, each Ti was octahedrally (Oh) bound by three terminal ONep ligands, one bidentate bridging OTHF ligand (μ_c-OTHF), and an oxygen from the other μ_c-OTHF ligand. For the OTPM derivatives, the product was identified as [(ONep) ₃Ti(μ-OTPM)]₂ (2). For this ligand, the soft S atom does not bind to the Ti but the O atom does act as a bridge between the two trigonal bipyramidal bound Ti metal centers. The OPy system yielded (OPy) ₂Ti(OR)₂ independent of the OR and the stoichiometry used [OR = ONep (3), OCHMe₂ (4), OCMe₃ (5)]. For 3-5, the two OPy ligands chelate to the Oh-bound Ti metal center with two terminal OR ligands. Compounds 1-5 were fully characterized using a variety of analytical techniques. An initial investigation of the proposed chemical stability of the '(OPy)₂Ti' moiety of 3-5 to alcoholysis exchange pathways involving (i) alkyl alcohols, (ii) aryl alcohols, (iii) substituted phenols, (iv) H-OR* derivatives, and (v) silanols proved successful through the isolation of a novel family of structurally characterized (OPy) ₂Ti(OR′)₂ (7-24) compounds.

Full text of DOI:10.1021/ic0618798

Inorg. Chem. 2007, 46, 1825−1835
Controlled Synthesis of a Structurally Characterized Family of Sterically
Constrained Heterocyclic Alkoxy-Modified Titanium Alkoxides
Timothy J. Boyle,* Robin M. Sewell, Leigh Anna M. Ottley, Harry D. Pratt III,
Christopher J. Quintana, and Scott D. Bunge†
Sandia National Laboratories, AdVanced Materials Laboratory, 1001 UniVersity BouleVard SE,
Albuquerque, New Mexico 87106
Received September 29, 2006
The reaction of [Ti(
[tetrahydrofurfuryl alcohol (H
termed H OR*], led to the isolation of a novel family of OR*-substituted titanium alkoxide precursors. Independent
of the initial stoichiometry for the H OTHF reaction, a monosubstituted, dinuclear species was isolated as [(ONep)3Ti-
c-OTHF)]2 (1). For 1, each Ti was octahedrally (Oh) bound by three terminal ONep ligands, one bidentate bridging
OTHF ligand ( c-OTHF), and an oxygen from the other c-OTHF ligand. For the OTPM derivatives, the product
was identified as [(ONep)3Ti( -OTPM)]2 (2). For this ligand, the soft S atom does not bind to the Ti but the O atom
does act as a bridge between the two trigonal bipyramidal bound Ti metal centers. The OPy system yielded
(OPy)2Ti(OR)2 independent of the OR and the stoichiometry used [OR ONep (3), OCHMe2 (4), OCMe3 (5)]. For
5, the two OPy ligands chelate to the Oh-bound Ti metal center with two terminal OR ligands. Compounds 1
were fully characterized using a variety of analytical techniques. An initial investigation of the proposed chemical
stability of the ‘(OPy)2Ti’ moiety of 3 5 to alcoholysis exchange pathways involving (i) alkyl alcohols, (ii) aryl alcohols,
(iii) substituted phenols, (iv) H OR* derivatives, and (v) silanols proved successful through the isolation of a novel
family of structurally characterized (OPy)2Ti(OR (7 24) compounds.
µ
-ONep)(ONep)3]2 (ONep
)
OCH2C(CH3)3) with a series of heterocyclic methanol derivatives
−OTHF), thiophene methanol (H
−
OTPM), or 2-pyridylcarbinol (H OPy) collectively
−
s
−
−
(µ
µ
µ
µ
)
3
−
−5
−
−
′
)
2
−
Introduction
ever, M(OR)x display a great deal of variability in their
nuclearity1-6 which is attributed to the small charge-to-large
cation radius ratio that requires the metal to bind additional
ligands (i.e., bridging) to complete their coordination sphere.4-6
Further complicating things is the fact that the alkoxide
ligands often decompose or react with modifiers to form
oxides, yielding unexpected structural rearrangements even
for supposed ‘simple’ modifications.1-12 This variability in
nuclearity makes tailoring material properties difficult since
a priori prediction of M(OR)x structures is not exact.
Therefore, it is of interest to develop M(OR)x compounds
that can be modified in a controlled manner.
Metal alkoxides (M(OR)x) are excellent precursors for the
preparation of ceramic oxide materials.1-6 In numerous
instances it has been clearly demonstrated that the structural
arrangement of the precursor plays a significant role in
determining the properties of the final materials.7-12 How-
* To whom correspondence should be addressed. Phone: (505)272-7625.
Fax: (505)272-7336. E-mail tjboyle@Sandia.gov.
† Current Address: Department of Chemistry, Kent State University, 305
Williams Hall, Kent, OH 44242-0001.
(1) Bradley, D. C.; Mehrotra, R. C.; Gaur, D. P. Metal Alkoxides;
Academic Press: New York, 1978.
(2) Bradley, D. C.; Mehrotra, R. C.; Rothwell, I. P.; Singh, A. Alkoxo
and Aryloxo DeriVatiVes of Metals; Academic Press: New York, 2001;
p 704.
(3) Turova, N. Y.; Turevskaya, E. P.; Kessler, V. G.; Yanovskaya, M. I.
The Chemistry of Metal Alkoxide; Kluwer Academic Publishers:
Boston, 2002; p 568.
(4) Caulton, K. G.; Hubert-Pfalzgraf, L. G. Chem. ReV. 1990, 90, 969.
(5) Chandler, C. D.; Roger, C.; Hampden-Smith, M. J. Chem. ReV. 1993,
93, 1205.
(6) Hubert-Pfalzgraf, L. G. New. J. Chem. 1987, 11, 663.
(7) Boyle, T. J.; Bunge, S. D.; Alam, T. M.; Holland, G. P.; Headley, T.
J.; Avilucea, G. Inorg. Chem. 2005, 44, 1309.
(8) Boyle, T. J.; Bunge, S. D.; Andrews, N. L.; Matzen, L. E.; Sieg, K.;
Rodriguez, M. A.; Headley, T. J. Chem. Mater. 2004, 24, 3279.
(9) Boyle, T. J.; Bunge, S. D.; Clem, P. G.; Richardson, J.; Dawley, J.
T.; Ottley, L. A. M.; Rodriguez, M. A.; Tuttle, B. A.; Avilucea, G.;
Tissot, R. G. Inorg. Chem. 2005, 44, 1588.
(10) Boyle, T. J.; A., R. M.; Ingersoll, D.; Headley, T. J.; Bunge, S. D.;
Pedrotty, D. M.; De’Angeli, S. M.; Vick, S. C.; Fan, H. Chem. Mater.
2003, 15, 3903.
(11) Boyle, T. J.; Schwartz, R. W. Comments Inorg. Chem. 1994, 16, 243.
(12) Boyle, T. J.; Tyner, R. P.; Alam, T. M.; Scott, B. L.; Ziller, J. W.;
Potter, B. G. J. Am. Chem. Soc. 1999, 121, 12104.
(13) Conquest Version 1.8, Cambridge Crystallographic Data Centre;
support@ccdc.cam.ac.uk or www.ccdc.cam.ac.uk (2004-Aug 2006
update).
10.1021/ic0618798 CCC: $37.00
Published on Web 01/05/2007
© 2007 American Chemical Society
Inorganic Chemistry, Vol. 46, No. 5, 2007 1825

Boyle et al.
between H-OPy and other Ti(OR)4 led to the isolation of
(OPy)2Ti(OR)2 where OR ) OCHMe2 (OiPr, 428) and
OCMe3 (OtBu, 5). The synthesis and characterization of these
OR* derivatives are discussed in detail.
Further, determining the reactivity of the ‘(OPy)2Ti’
moiety to alcohol substitution was undertaken using a series
of sterically varied: (i) alkyl alcohols, (ii) aryl alcohols, (iii)
substituted arylalcohols, (iv) H-OR*, and (v) silanols,
including (i) 2-methyl propanol (H-OPrMe), 2,2′-diphenyl
ethanol (H-DPE), 1-adamantanol (H-OAdam); (ii) 4-ada-
mantane phenol (H-OPh-Adam), ortho-methylphenol (H-
oMP), ortho-propylphenol (H-oPP), ortho-butylphenol (H-
oBP), 2,6-dimethylphenol (H-DMP), 2,6-diisopropylphenol
(H-DIP), 2,6-di-tert-butylphenol (H-DBP), 2,6-diphe-
nylphenol (H-DPP); (iii) 2-bromophenol (H-2BP) 2,4,6-
trichlorophenol (H-TCP), 4-mercaptophenol (H-4MP),
4-aminophenol (H-4AP), 2,3-diaminophenol (H-DAP); (iv)
H-OTPM, (v) dimethyl-tert-butylsilanol (H-DMBS), triph-
enylsilanol (H-TPS), tri-tert-butoxysilanol (H-TOBS). The
products isolated and crystallographically characterized were
found to be the isostructural species (OPy)2Ti(OR′)2 where
OR′ ) DPE (7), OPh-Adam (8), oPP (10), oBP (11), DMP
(12), DIP (13), DPP (15), 2BP (16), TCP (17), 4MP (18),
4AP (19), DAP (20), OTPM (21), DMBS (22), TPS (23),
and TOBS (24). Crystal structures of the disubstituted species
for OPrMe (6), oMP (9), and DBP (14) were not obtained.
Full details are presented on the synthesis and structures of
1-24.
Figure 1. Schematic representation of the H-OR* family of ligands (a)
H-OTHF, (b) H-OTPM, and (c) H-OPy.
One method to limit structural rearrangements or uncon-
trolled cluster formation is to introduce bidentate ligands,1-6,13
such as tetrahydrofurfuryl alcohol (H-OTHF, shown in
Figure 1a). The OTHF ligand along with thiophene methanol
(H-OTPM), and pyridine methanol or 2-pyridylcarbinol
(H-OPy) analogues have been collectively referred to as
H-OR*.14-16 These OR* ligands are of interest due to their
pendent alcohol chain, high solubility, and the varied rigid
heterocycles which resemble solvents widely used in M(OR)4
syntheses.14-16 The OTHF ligand has been successfully used
to minimize cluster formation in metal alkyl systems17-26
and was of interest to determine the utility of this, and the
other OR* ligand in controlling the structural characteristics
of M(OR)x.
A survey of the literature showed that no systematic
investigation of the OR* ligands with Group 4 cations was
available.13 This study sought to fill this void and explore
the controlled construction of Ti(OR)4. The H-OR* ligands
were reacted with the previously isolated [Ti(µ-ONep)-
Experimental Section
27
(ONep)3]2 (ONep ) OCH2CMe3) to form [(µc-OTHF)Ti-
All compounds described below were handled with rigorous
exclusion of air and water using standard Schlenk line and glove
box techniques. All solvents were used as received (Aldrich) in
sure-seal bottles and only handled under an inert atmosphere of
argon. The following compounds were stored under argon upon
receipt (Aldrich) and used without further purification: Ti(OR)4
(OR ) OiPr, OtBu), H-ONep, H-OTHF, H-OTPM, H-OPy,
H-OPrMe, H-OAdam, H-DPE, H-OPh-Adam, H-oMP, H-oPP,
H-oBP, H-DMP, H-DIP, H-DBP, H-DPP, H-2BP, H-TCP,
H-4MP, H-4AP, H-DAP, H-DMBS, H-TPS, and H-TOBS.
[Ti(µ-ONep)(ONep)3]2 was synthesized according to the literature
report.27
(ONep)3]2 (1; µc ) chelating bridging), [(µ-OTPM)Ti-
(ONep)3]2 (2), and (OPy)2Ti(ONep)2 (3). Additional reactions
(14) Andrews, N. L.; Boyle, T. J. In Synthesis and characterization of noVel
early, late, and lanthanide metals modified with bidentate alkoxide
ligands; 225th National Meeting of the American Chemical Society,
New Orleans, LA, March 23-27, 2003; pp U71-U71.
(15) Boyle, T. J.; Rodriguez, M. A.; Alam, T. M.; Bunge, S. D. In
Controlled construction of metal alkoxides using polydentate alcohols;
227th National Meeting of the American Chemical Society, Anaheim,
CA, March 28-April 01, 2004; p U1562.
(16) Hernandez-Sanchez, B. A.; Boyle, T. J.; Rodriguez, M. A.; Alam, T.
M. In Rational construction of group IV metal alkoxide structures
using sterically rigid bridging ligands; 229th National Meeting of the
American-Chemical-Society, San Diego, CA, March 13-17, 2005;
pp U1019-U1019.
(17) John, L.; Utko, J.; Jerzykiewicz, L. B.; Sobato, P. Inorg. Chem. 2005,
44, 9131.
(18) Jerzykiewicz, L. B.; Utko, J.; Sobota, P. Acta Crystallogr., Sect. C:
Cryst. Struct. Commun. 1997, 53, 1393.
(19) Janas, Z.; Sobota, P.; Kimowicz, M.; Szafert, S.; Szczegot, K.;
Jerzykiewicz, L. B. J. Chem. Soc. Dalton Trans. 1997, 3897.
(20) Janas, Z.; Sobota, P.; Kasprzak, M.; Glowiak, T. Chem. Commun.
1996, 2727.
(21) Sobota, P.; Utko, J.; Ejfler, J.; Jerzykiewicz, L. B. Organometallics
2000, 19, 4929.
Analytical data were collected on dried crystalline samples. FT-
IR data were obtained on a Bruker Vector 22 MIR spectrometer
using KBr pellets under an atmosphere of flowing nitrogen.
Elemental analyses were performed on a Perkin-Elmer 2400 CHN-
S/O elemental analyzer. NMR spectra were collected on a Bruker
1
DRX400 spectrometer at 400.1 MHz for H experiments using
concentrated crystalline samples dissolved in toluene-d8.
General Synthesis. Due to the similarity of the syntheses of
these compounds, a general preparatory route is presented. To a
stirring clear solution of Ti(OR)4 in toluene, the appropriate H-OR*
was added via pipet and left to stir. After 12 h, the reactions were
set aside to slowly evaporate the volatile component of the reaction
until X-ray quality crystals formed.
(22) Sobota, P.; Utko, J.; Janas, Z.; Szafert, S. Chem. Commun. 1996, 1923.
(23) Sobota, P.; Utko, J.; Sztajnowska, K.; Ejfler, J.; Jerzykiewicz, L. B.
Inorg. Chem. 2000, 39, 235.
(24) Janas, Z.; Jerzykiewicz, L. B.; Sobota, P.; Utko, J. New J. Chem. 1999,
23, 185.
(25) Utko, J.; Przybylak, S.; Jerzykiewicz, L. B.; Szafert, S.; Sobota, P.
Chem.-Eur. J. 2003, 9, 181.
(26) Boyle, T. J.; Alam, T. M.; Bunge, S. D.; Segall, J. M.; Avilucea, G.
R.; Tissot, R. G.; Rodriguez, M. A. Organometallics 24, 731.
(27) Boyle, T. J.; Alam, T. M.; Mechenbier, E. R.; Scott, B. L.; Ziller, J.
W. Inorg. Chem. 1997, 36, 6479.
[(µc-OTHF)Ti(ONep)3]2 (1). Used Ti(ONep)4 (2.00 g, 5.05
mmol), H-OTHF (0.516 g, 5.05 mmol), ∼10 mL of toluene. Yield
(28) Aragon, P. J.; Carrillo-Hermosilla, F.; Villasenor, E.; Otero, A.;
Antinolo, A.; Rodriguez, A. M. Eur. J. Inorg. chem. 2006, 965.
1826 Inorganic Chemistry, Vol. 46, No. 5, 2007

Heterocyclic Alkoxy-Modified Titanium Alkoxides
1.82 g (87.9%). FTIR (KBr pellet, cm-1) 3365 (w), 2952 (s), 2904
(s), 2866 (s), 2940 (sh), 2691 (m), 2634 (w), 2569 (w), 2506 (vw),
2403 (w), 2367 (w), 2293 (w), 2206 (w), 2140 (w), 1484 (s), 1463
(sh), 1393 (s), 1361 (s), 1331 (sh), 1292 (m), 1257 (m), 1216 (sh),
1067 (s), 1022 (sh), 953 (sh), 933 (m), 902 (m), 850 (sh), 814 (m),
750 (m), 678 (s), 554 (m), 482 (s). 1H NMR (400.1 MHz, toluene-
d8) δ 4.37 (2H, bs, OCH2(OC4H7)), 4.25 (6H, s, OCH2C(CH3)3),
4.04 (1H, bs, OCH2(OC4H7)), 3.69 (2H, bs, OCH2(OC4H7)), 1.71
(2H, bs, OCH2(OC4H7)), 1.56 (2H, bs, OCH2(OC4H7)), 1.04 (28H,
s, OCH2C(CH3)3). Anal. Calcd for C20H42O5Ti: 58.53 %C, 10.31
%H. Found: 57.84 %C, 10.32 %H.
5.54 (0.3H, s, OCH2(NC5H4)), 1.35 (26H, s, OC(CH3)3)). Anal.
Calcd for C20H30N2O4Ti: 58.54 %C, 7.37 %H, 6.83 %N. Found:
58.18 %C, 6.95 %H, 6.83 %N.
General Alkoxide Substitution Synthesis. Due to the similarity
of the syntheses of these compounds, a general preparatory route
is presented. To a stirring clear solution of 4 in toluene, the
appropriate H-OR′ was added and left to stir. For any of the
compounds that did not instantly form a clear solution, the reaction
mixture was heated until clear. For the amide-substituted species,
it was necessary to add pyridine and heat to solubilize the reaction
mixture. After 12 h, the reactions were set aside to slowly evaporate
the volatile component of the reaction until X-ray quality crystals
formed. Yields are based on the first batch of crystals isolated and
were not optimized.
(OPy)2Ti(OiPr)(OPrMe) (6a). Used 4 (1.00 g, 2.62 mmol),
H-OPrMe (0.640 g, 5.23 mmol), ∼5 mL of toluene. Anal. Calcd
for C19H28N2O4Ti: 57.58 %C, 7.12 %H, 7.07 %N. Found: 55.61
%C, 7.05 %H, 6.71 %N.
(OPy)2Ti(OAdam)2 (6b). Used 4 (1.00 g, 2.62 mmol), H-OAd-
am (0.796 g, 5.23 mmol), ∼5 mL of toluene. Anal. Calcd for
C32H42N2O4Ti: 67.84 %C, 7.47 %H, 4.94 %N. Found: 67.34 %C,
7.38 %H, 5.15 %N.
(OPy)2Ti(DPE)2 (7). Used 4 (1.00 g, 2.62 mmol), H-DPE (1.04
g, 5.23 mmol), ∼5 mL of toluene. Yield 1.09 g (63.4%). Anal.
Calcd for C47H46N2O4Ti(7‚tol): 75.19 %C, 6.18 %H, 3.73 %N.
Found: 75.11 %C, 6.15 %H, 3.19 %N.
(OPy)2Ti(OPh-Adam)2 (8). Used 4 (1.00 g, 2.62 mmol),
H-OPh-Adam (1.19 g, 5.23 mmol), ∼5 mL of toluene. Yield
0.906 g (48.0%). Anal. Calcd for C51H58N2O4Ti (8‚tol): 75.53 %C,
7.21 %H, 3.46 %N. Found: 75.00 %C, 7.10 %H, 3.68 %N.
(OPy)2Ti(oMP)2 (9). Used 4 (1.00 g, 2.62 mmol), H-oMP (0.57
g, 5.23 mmol), ∼5 mL of toluene. Yield 0.512 g (40.8%). Anal.
Calcd for C26H26N2O4Ti: 65.28 %C, 5.48 %H, 5.86 %N. Found:
64.99 %C, 5.28 %H, 5.96 %N.
[(µ-OTPM)Ti(ONep)3]2 (2). Used Ti(ONep)4 (2.00 g, 5.05
mmol), H-OTPM (0.577 g, 5.05 mmol), ∼10 mL of toluene. Yield
2.01 g (94.4%). FTIR (KBr pellet, cm-1) 2903(s), 2681(m), 1606-
(m), 1570(sh), 1478(m), 1274(m), 1089(s), 843(sh), 762(s). 1H
NMR (400.1 MHz, toluene-d8) δ 6.90 (1H, bs, OCH2(SC4H3)), 6.87
(1H, dd, OCH2(SC4H3)), JH-H ) 2.8 Hz), 6.74 (1H, mult, OCH2-
(SC4H3)), JH-H ) 3.6 Hz), 5.53 (2H, s, OCH2(SC4H3)), 4.00 (6H,
s, OCH2C(CH3)3), 0.94 (41H, s, OCH2C(CH3)3). Anal. Calcd for
C20H38O4STi: 56.86 %C, 9.07 %H. Found: 56.86 %C, 9.15 %H.
(OPy)2Ti(ONep)2 (3). Used Ti(ONep)4 (2.00 g, 5.05 mmol),
H-OPy (1.10 g, 10.1 mmol), ∼10 mL of toluene. Yield 2.02 g
(91.4%). FTIR (KBr pellet, cm-1) 2950.36(s), 2902.77(s), 2857.89-
(s), 2795(s), 1605(s), 1478(s), 1435(s), 1391(m), 1356(s), 1271-
(m), 1147(s), 1083(s), 1043(s), 1020(s), 761(s), 724(s), 658(s),
1
538(s), 481(s), 451(m). H NMR (400.1 MHz, toluene-d8) δ 8.62
(1H, dd, OCH2(NC5H4), JH-H ) 2.60 Hz), 6.73 (1H, dt, OCH2-
(NC5H4), JH-H ) 7.2 Hz) 6.45 (1H, dt, OCH2(NC5H4), JH-H ) 4.0
Hz) 6.35 (1H, dd, OCH2(NC5H4), JH-H ) 4.0 Hz), 5.52 (0.2H, s,
OCH2(NC5H4)), 5.51 (2H, s, OCH2(NC5H4)) 4.32 (2H, s, OCH2C-
(CH3)3)), 1.10 (11H, s, OCH2C(CH3)3)). Anal. Calcd for C22H34N2O4-
Ti: 60.27 %C, 7.82 %H, 6.39 %N. Found: 59.77 %C, 7.00 %H,
6.08 %N.
(OPy)2Ti(OiPr)2 (4). Used Ti(OiPr)4 (2.00 g, 7.04 mmol),
H-OPy (1.54 g, 14.1 mmol), ∼10 mL of toluene. Yield 2.56 g
(95.2%). FTIR (KBr pellet, cm-1) 3095 (sh), 3075 (m), 3060(sh),
3030 (m), 2961 (s), 2923 (s), 2855 (sh), 2838 (sh), 2817 (s), 2781
(sh), 2689 (s), 2656 (sh), 2609 (m), 2301 (m), 2344 (m), 2332 (m),
1604 (s), 1570 (s), 1523 (w), 1474 (s), 1549 (sh), 1438 (s), 1371
(s), 1356 (s), 1320 (s), 1277 (s), 1222 (s), 1159 (s), 1125 (s), 1095
(s), 1047 9s), 994 (s), 843 (s), 823 (sh), 775 (s), 722 (s), 643 (s),
601 (s), 636 (s). 1H NMR (400.1 MHz, toluene-d8) δ 8.62 (1H, dd,
OCH2(NC5H4), JH-H ) 5.2 Hz) 6.19 (1H, dt, OCH2(NC5H4), JH-H
) 7.2 Hz), 6.50 (1H, dt, OCH2(NC5H4), JH-H ) 7.2 Hz), 6.40 (1H,
dd, OCH2(NC5H4), JH-H ) 7.6 Hz), 5.74, (0.2H, s, OCH2(NC5H4)),
(OPy)2Ti(oPP)2 (10). Used 4 (1.00 g, 2.62 mmol), H-oPP (0.713
g, 5.23 mmol), ∼5 mL of toluene. Yield 0.440 g (31.5%). Anal.
Calcd for C30H34N2O4Ti: 67.42 %C, 6.41 %H, 5.24 %N. Found:
66.91 %C, 6.78 %H, 5.15 %N.
(OPy)2Ti(oBP)2 (11). Used 4 (1.00 g, 2.62 mmol), H-oBP
(0.786 g, 5.23 mmol), ∼5 mL of toluene. Yield 1.28 g (87.1%).
Anal. Calcd for C32H38N2O4Ti: 68.32 %C, 6.80 %H, 4.97 %N;
for C35.5H42N2O4Ti (11‚1/2tol): 70.06 %C, 6.95 %H, 4.60 %N;.
Found: 69.48 %C, 6.65 %H, 4.28 %N.
(OPy)2Ti(DMP)2 (12). Used 4 (1.00 g, 2.62 mmol), H-DMP
(0.638 g, 5.23 mmol), ∼5 mL of toluene. Yield 0.822 g (62.0%).
Anal. Calcd for C28H30N2O4Ti: 66.41 %C, 5.97 %H, 5.53 %N.
Found: 66.07 %C, 6.17 %H, 5.78 %N.
5.52 (2H, s, OCH2(NC5H4)), 5.02 (1H, s, OCH(CH3)2), JH-H
)
6.0 Hz), 1.30 (6H, d, OCH(CH3)2), JH-H ) 6.0 Hz). Anal. Calcd
for C18H26N2O4Ti: 56.55 %C, 6.86 %H, 7.33 %N. Found: 56.55
%C, 6.85 %H, 7.32 %N
(OPy)2Ti(DIP)2 (13). Used 4 (1.00 g, 2.62 mmol), H-DIP (0.933
g, 5.23 mmol), ∼5 mL of toluene. Yield 0.457 g (28.2%). Anal.
Calcd for C36H46N2O4Ti: 69.89 %C, 7.49 %H, 4.53 %N. Found:
69.68 %C, 7.77 %H, 4.31 %N.
(OPy)2Ti(DPP)2 (15). Used 4 (1.00 g, 2.62 mmol), H-DPP (1.29
g, 5.23 mmol), ∼5 mL of toluene. Yield 1.74 g (88.3%). Anal.
Calcd for C55H46N2O4Ti (15• tol): 78.31 %C, 5.40 %H, 3.26 %N.
Found: 78.03 %C, 5.51%H, 3.17 %N.
(OPy)2Ti(2BP)2 (16). Used 4 (1.00 g, 2.62 mmol), H-2BP
(0.905 g, 5.23 mmol), ∼5 mL of toluene. Yield 1.74 g (81.7%).
Anal. Calcd for C24H20Br2N2O4Ti: 47.40 %C, 3.32 %H, 4.61 %N.
Found: 46.57 %C, 3.21 %H, 4.14 %N.
(OPy)2Ti(TCP)2 (17). Used 4 (10.0 g, 26.2 mmol) H-TCP (10.4
g, 52.4 mmol), ∼50 mL of toluene. Yield 16.4 g (83.6%). Anal.
Calcd for C24H16Cl6N2O4Ti: 43.88 %C, 2.45 %H, 4.26 %N.
Found: 43.73 %C, 2.31 %H, 4.29 %N.
(OPy)2Ti(OtBu)2 (5). Used Ti(OtBu)4 (2.00 g, 5.88 mmol),
H-OPy (1.28 g, 11.8 mmol), ∼10 mL of toluene. Yield 1.65 g
(68.5%). FTIR (KBr pellet, cm-1) 3173 (w), 3139 (w), 3095 (sh),
3074 (m), 3058 (sh), 3024 (m), 2966 (s), 2923 (s), 2854 (s), 2836
(s), 2814 (s), 2780 (sh), 2960 (m), 2656 (w), 2610 (w), 2570 (w),
1608 (s), 1574 (m), 1481 (m), 1462 (sh), 1441 (s), 1369 (sh), 1357
(s), 1323 (s), 1280 (m), 1262 (sh), 1224 (m), 1160 (s), 1122 (s),
1091 (s), 1063 (sh), 1048 (s), 995 (s), 847 (s), 825 (sh), 847 (s),
775 (s), 720 (s), 646 (s), 639 (s), 599 (s), 538 (s), 485 (m), 457
1
(m), 448(sh). H NMR (400.1 MHz, toluene-d8) δ 8.69 (1H, dd,
OCH2(NC5H4), JH-H ) 2.4 Hz), 6.79 (1H, dt, OCH2(NC5H4), JH-H
) 7.6 Hz), 6.47 (1H, dt, OCH2(NC5H4) JH-H ) 6.0 Hz), 6.41 (1H,
dd, OCH2(NC5H4) JH-H ) 3.2 Hz), 5.52 (2H, s, OCH2(NC5H4)),
Inorganic Chemistry, Vol. 46, No. 5, 2007 1827

Boyle et al.
Table 1. Data Collection Parameters for 1-5
compound
1
2
chemical formula
fw
C40H84O10Ti2
820.86
C20H38O4STi
422.12
temp (K)
space group
a (Å)
203(2)
orthorhombic Pbcn
24.107(4)
173(2)
monoclinic, P2(1)/n
9.894(2)
b (Å)
c (Å)
10.4854(16)
19.624(3)
24.600(6)
39.224(9)
90.016(5)
9546(4)
â (deg)
V (Å3)
4960.6(13)
compound
3
4
5
chemical formula
fw
C22H34N2O4Ti
438.20
C18H26N2O4Ti
382.30
C20H30N2O4Ti
410.35
temp (K)
space group
a (Å)
b (Å)
c (Å)
168(2)
168(2)
168(2)
monoclinic Cc
10.185(2)
22.944(6)
10.047(2)
91.516(18)
2346.9(9)
4
1.241
0.393
4.78 (9.01)
9.90 (11.66)
monoclinic P21/n
11.268(2)
14.820(3)
12.104(2)
92.635(4)
2019.1(7)
4
1.258
0.446
5.92 (7.89)
13.27 (14.11)
monoclinic P21/c
15.122(4)
17.851(5)
16.628(4)
101.728(5)
4395(2)
â (deg)
V (Å3)
Z
D
8
calcd(Mg/m3)
1.240
0.415
8.88 (20.42)
16.05 (24.65)
µ,(Mo, KR) (mm-1
R1 (%) (all data)
wR2 (%) (all data)
)
a R1 ) ∑||Fo| - |Fc||/∑|Fo| × 100. b wR2 ) [∑w(Fo - Fc )2/∑(w|Fo| )2]1/2 × 100.
2
2
2
(OPy)2Ti(4MP)2 (18). Used 4 (10.0 g, 26.2 mmol), H-4MP
(6.60 g, 52.3 mmol), ∼50 mL of pyridine, heated to dissolution.
Yield 11.3 g (84.5%). Anal. Calcd for C24H22N2O4S2Ti: 56.03 %C,
4.31 %H, 5.45 %N. Found: 55.97 %C, 4.16 %H, 5.40 %N.
(OPy)2Ti(4AP)2 (19). Used 4 (6.27 g, 16.4 mmol), H-4AP (3.58
g, 32.8 mmol), ∼50 mL of pyridine, heated to dissolution. Yield
8.97 g (97.1% for 19‚py). Anal. Calcd for C24H24N4O4Ti: 60.01
%C, 5.04 %H, 11.66 %N. Found: 60.65 %C, 5.08 %H, 11.74%N.
(OPy)2Ti(DAP)2 (20). Used 4 (10.0 g, 26.2 mmol), H-DAP
(6.50 g, 52.3 mmol), ∼50 mL of pyridine, heated to dissolution.
Yield 13.0 g (84.4% for 19‚py). Anal. Calcd for C24H26N6O4Ti:
56.93 %C, 4.38 %H, 16.59 %N. C29H31N7O4Ti (19‚py): 59.09 %C,
5.30 %H, 16.63 %N. Found: 58.57 %C, 4.96 %H, 15.84 %N.
(OPy)2Ti(OTPM)2 (21). Used 4 (1.00 g, 2.62 mmol), H-OTPM
(0.597 g, 5.23 mmol), ∼5 mL of toluene. Yield 1.03 g (80.1%).
Anal. Calcd for C22H22N2O4S2Ti: 53.88 %C, 4.52 %H, 5.71 %N.
Found: 54.16 %C, 4.70 %H, 5.93 %N.
determination and data collection were carried out using SMART
Version 5.054 software. Data reduction was performed using
SAINTPLUS Version 6.01 software and corrected for absorption
using the SADABS program within the SAINT software package.
Structures were solved using direct methods that yielded the
heavy atoms, along with a number of the lighter atoms or by using
the PATTERSON method which yielded the heavy atoms. Subse-
quent Fourier syntheses yielded the remaining light-atom positions.
The hydrogen atoms were fixed in positions of ideal geometry and
refined using SHELXS software. The final refinement of each
compound included anisotropic thermal parameters for all non-
hydrogen atoms. It is of note that crystal structures of M(OR)x often
contain disorder within the atoms of the ligand chain causing higher
than normal final correlations.1-6 All final CIF files were checked
at http://www.iucr.org/. Additional information concerning the data
collection and final structural solutions can be found in the
Supporting Information. Data collection parameters for 1-5 are
given in Table 1 and that for 6a-24 are found in Table 2. Metrical
data for the high-quality structures are listed in Table 3. Specific
issues associated with individual structures are discussed below.
(OPy)2Ti(DMBS)2 (22). Used 4 (1.00 g, 2.62 mmol), H-DMBS
(0.693 g, 5.23 mmol), ∼5 mL of toluene. Yield 0.450 g (32.8%).
Anal. Calcd for C24H42N2O4Si2Ti: 54.73 %C, 8.04 %H, 5.32 %N.
Found: 54.54 %C, 8.03 %H, 5.28 %N.
The metrical data of 1 and 2 were not of sufficient quality to be
useful for analysis but do establish the connectivity of the final
compounds. The final solutions were not included in the CIF file,
and only limited crystal data parameters were presented in Table 2
for identification purposes. For structures 8, 11, and 17, it was
necessary to squeeze disorder electron density of 494.9, 446.6, and
677.4 Å3, respectively, which is in agreement with ∼1 toluene
molecule. The structure of 8 solved in the space groups (P1h, P1,
and Cc) but not in the C2/c as suggested by the ADDSYM program
with P1h yielding the best solution. The structure of 3 was solved
in the monoclinic non-centrosymmetric space group Cc with well-
behaved thermal ellipsoids and a clear break in symmetry that could
be observed due to the t-butyl groups. Compound 18 was solved
in the triclinic P1 space group, rather than P1h as suggested by
ADDSYM, with well-behaved thermal ellipsoids and a clear break
in symmetry due to the 4MP groups.
(OPy)2Ti(TPS)2 (23). Used 4 (1.00 g, 2.62 mmol), H-TPS (1.45
g, 5.23 mmol), ∼5 mL of toluene. Yield 1.06 g (50.2%). Anal.
Calcd for C48H42N2O4Si2Ti: 70.75 %C, 5.19 %H, 3.44 %N.
Found: 70.30 %C, 5.06 %H, 3.68 %N.
(OPy)2Ti(TOBS)2 (24). Used 4 (1.00 g, 2.62 mmol), H-TOBS
(1.38 g, 5.23 mmol), ∼5 mL of toluene. Yield 0.938 g (46.0%).
Anal. Calcd for C36H66N2O10Si2Ti: 54.67 %C, 8.41 %H, 3.54 %N.
Found: 54.74 %C, 8.22 %H, 3.36 %N.
General X-ray Crystal Structure Information.29 Crystals were
mounted onto a glass fiber from a pool of Fluorolube and
immediately placed in a cold N2 vapor stream, on a Bruker AXS
diffractometer equipped with a SMART 1000 CCD detector using
graphite-monochromatized Mo KR radiation (λ ) 0.7107 Å). Lattice
(29) Caulton, K. G.; Chisholm, M. H.; Drake, S. R.; Folting, K. Chem.
Commun. 1990, 1349.
1828 Inorganic Chemistry, Vol. 46, No. 5, 2007

Heterocyclic Alkoxy-Modified Titanium Alkoxides
Table 2. Data Collection Parameters for 6a-8, 10-13, and 15-24
compound
6a
7‚tol
8
10
11
12
chemical formula
fw
C19H28N2O4Ti
396.32
C40H38N2O4Ti‚C7H8
750.77
C44H50N2O4Ti
718.76
C30H34N2O4Ti
534.49
C32H38N2O4Ti
562.54
C28H30 N2O4Ti
506.44
temp (K)
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
152(2)
203(2)
203(2)
173(2)
173(2)
173(2)
monoclinic C2/c
26.126(4)
11.7662(16)
19.326(3)
monoclinic P21/c
9.0231(16)
12.405(2)
monoclinic P2(1)/n
14.9826(10)
17.7669(12)
15.9923(11)
triclinic P1h
12.663(8)
13.221(8)
14.489(12)
63.106(11)
82.596(19)
89.942(13)
2141(3)
Monoclinic P2(1)/c
12.1440(17)
14.409(2)
triclinic P1h
10.3667(16)
13.955(2)
14.328(2)
69.324(3)
85.345(3)
68.971(3)
9546(4)
18.676(3)
16.027(2)
99.375(3)
111.4920(10)
97.499(2)
121.224
2062.5(6)
4
1.276
0.439
8.50 (20.33)
11.51 (22.42)
3961.1(5)
4
1.259
0.262
4.34 (10.86)
5.59 (11.69)
2780.6(7)
4
1.277
0.345
6.60 (9.89)
14.16 (15.68)
5080.3(12)
8
1.324
0.373
Z
D
2
2
calcd(Mg/m3)
1.115
0.240
8.85(17.70)
20.14(21.42)
1.034
0.268
4.39(5.71)
10.42(11.02)
µ(Mo KR) (mm-1
)
R1a (%) (all data)
3.48 (3.94) 8.97 (9.31)
wR2b (%) (all data)
compound
13
15‚tol
16
17
18
19‚py
chemical formula
fw
temp (K)
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
C36H46N2O4Ti
618.65
157(2)
C48H38N2O4Ti‚C7H8 C24H20Br2N2O4Ti C24H16Cl6 N2O4Ti C24H22N2O4S2Ti C24H24N4O4Ti‚C5H5N
846.84
160(2)
608.12
656.96
514.45
559.47
297(2)
203(2)
203(2)
273(2)
monoclinic P2(1)/n monoclinic P2(1)/n
triclinic P1h
8.995(18)
11.89(2)
12.11(2)
95.62(3)
90.64(3)
102.69(3)
1257(4)
2
monoclinic C2/c
14.5686(11)
8.4738(6)
26.0177(19)
triclinic P1
8.4060(13)
10.4494(16)
14.278(2)
104.405(3)
90.340(3)
99.668(3)
1195.9(3)
2
orthorhombic Pccn
12.5716(18)
12.8307(19)
16.406(2)
13.142(4)
15.747(4)
17.206(5)
17.035(4)
12.937(3)
19.793(4)
110.007(4)
98.875(4)
95.6800(10)
3345.7(16)
4
1.228
0.296
3.46 (3.84))
4309.7(16)
4
3196.2(4)
4
2646.3(7)
4
Z
D
calcd(Mg/m3)
1.305
1.607
1.365
1.429
1.404
µ(Mo KR) (mm-1
)
0.251
3.551
0.799
0.566
0.369
R1a (%) (all data)
4.76 (10.04)
7.10 (11.04)
7.87 (17.28)
19.66 (26.03)
4.24 (9.94)
4.95 (10.29)
7.66 (14.42)
8.21 (14.92)
7.50 (12.07)
12.44 (13.74)
wR2b (%) (all data) 8.95 (9.26
compound
20‚py
21
22
23
24
chemical formula
fw
C24H26N6O4Ti‚ C5H5N
589.49
C22H22N2O4S2Ti
490.43
C24H42N2O4Si2Ti
526.66
C48H42N2O4Si2Ti
814.92
C36H66N2O10Si2Ti
790.98
temp (K)
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
173(2)
monoclinic P2(1)/n
13.045(3)
12.353(2)
18.017(4)
168(2)
monoclinic C2/c
23.995(5)
14.479(3)
16.710(3)
203(2)
203(2)
203(2)
monoclinic P1h
9.198(6)
14.460(9)
18.529(12)
108.046(9)
97.543(9)
103.088(10)
2228(2)
triclinic P1h
9.9310(15)
14.414(2)
21.413(3)
92.430(3)
100.152(2)
101.664(3)
2998.4(8)
2
1.167
0.394
8.63 (19.58)
15.19 (23.70)
monoclinic P2(1)/n
13.5219(15)
15.4673(17)
20.153(2)
94.391(4)
129.346(4)
100.152(2)
2894.7(10)
4
1.353
0.343
7.28 (13.71)
13.71(15.98)
4492(3)
8
1.386
0.596
15.98 (38.14)
25.24 (43.16)
4149.1(8)
4
1.305
0.311
4.91 (10.74)
6.94 (11.73)
Z
D
2
calcd(Mg/m3)
1.179
0.296
9.65 (26.33)
10.23 (26.55)
µ(Mo KR) (mm-1
)
R1a (%) (all data)
wR2b (%) (all data)
2
2
2
a R1 ) ∑||Fo| - |Fc||/∑ |Fo| × 100. b wR2 ) [∑w(Fo - Fc )2/∑ (w|Fo| )2]1/2 × 100.
Results and Discussion
characterization, and structure of these compounds are
discussed below.
As mentioned previously, there are several alkyl OTHF
species known and numerous examples of metal halide
derivatives of the OTHF species; however, there are no
OTHF-substituted transition M(OR)x reported in the litera-
ture.13 Further, there are no examples of OTPM-substituted
transition metal species reported. In contrast, there are
numerous examples of OPy-substituted species available
bound to a wide variety of transition metals but surprisingly
none with any of the Group 4 cations.13 While preparing
this report, (OPy)2Ti(OiPr)2 was published which is discussed
below.28 We undertook the reaction of [Ti(µ-ONep)-
Synthesis. A stoichiometric (1:1 and 1:2) investigation of
the reactivity between [Ti(µ-ONep)(ONep)3]2 and the
27
HOR* was undertaken according to eq 1. After being stirred
for 12 h, each clear reaction mixture was dried by rotary
evaporation, yielding off-white powders. For the majority
of these reactions, crystals were isolated through slow
evaporation of the volatile component of the reaction mixture.
Upon analysis, it was found that the OTHF system consis-
tently generated the monosubstituted species and the OPy
system consistently generated the disubstituted species. All
attempts to change the stoichiometry through substoichio-
27
(ONep)3]2 with H-OR* ligands (eq 1). The synthesis,
Inorganic Chemistry, Vol. 46, No. 5, 2007 1829

Boyle et al.
Table 3. Metrical Data for (OPy)2Ti(OR)2 Derivatives
av Ti-NOPy (Å)
av Ti-OOPy (Å)
av Ti-OR (Å)
compd
OR abbrev
selected angles (deg)
color
UV-vis λmax (tol, nm)
H-OPy
H-OPy
ONep
-
-
pale brown
white
281
283
3
2.25
1.92
1.86
O(3)-Ti(1)-O(4) 101.34(18)
O(3)-Ti(1)-N(1) 89.9(7)
O(1)-Ti(1)-O(2) 153.65(18)
O(3)-Ti(1)-N(2) 165.8(6)
O(3)-Ti(1)-O(4) 102.13(12)
O(3)-Ti(1)-N(2) 89.42(11)
O(2)-Ti(1)-O(1) 154.51(10)
O(4)-Ti(1)-N(2) 165.19(10)
O(2)-Ti(1)-O(1) 103.2(2)
O(2)-Ti(1)-N(1) 90.3(2)
O(4)-Ti(1)-O(3) 154.14(19)
O(1)-Ti(1)-N(1) 163.7(2)
O(4)-Ti(1)-O(3) 103.28(6)
O(3)-Ti(1)-N(2) 87.55(6)
O(1)-Ti(1)-O(2) 154.28(6)
O(4)-Ti(1)-N(2) 165.36(6)
O(1)-Ti(1)-O(2) 100.86(18)
N(2)-Ti(1)-O(3) 84.8(3)
O(3)-Ti(1)-O(4) 153.64(18)
O(1)-Ti(1)-N(2) 162.2(4)
O(1)-Ti(1)-O(2) 98.72(10)
O(1)-Ti(1)-N(2) 88.73(10)
O(3)-Ti(1)-O(4) 155.26(10)
N(1)-Ti(1)-O(1) 167.44(10)
O(1)-Ti(1)-O(3) 97.8(3)
O(2)-Ti(1)-N(1) 85.8(3)
O(2)-Ti(1)-O(4) 154.3(2)
N(1)-Ti(1)-O(3) 170.2(3)
O(1)-Ti(1)-O(2) 98.89(6)
O(3)-Ti(1)-N(1) 83.04(6)
O(3)-Ti(1)-O(4) 151.90(6)
O(1)-Ti(1)-N(2) 166.99(6)
O(1)-Ti(1)-O(2) 98.62(6)
O(3)-Ti(1)-N(2) 83.30(6)
O(3)-Ti(1)-O(4) 152.09(6)
O(2)-Ti(1)-N(3) 165.63(6)
O(4)-Ti(1)-O(3) 98.79(8)
O(2)-Ti(1)-N(1) 83.41(8)
O(1)-Ti(1)-O(2) 150.44(8)
O(3)-Ti(1)-N(1) 167.95(8)
O(3)-Ti(1)-O(4) 99.8(4)
O(2)-Ti(1)-N(2) 85.9(3)
O(1)-Ti(1)-O(2) 153.6(3)
O(3)-Ti(1)-N(2) 168.1(3)
O(3)-Ti(1)-O(4) 99.27(13)
O(3)-Ti(1)-N(2) 87.9(3)
O(1)-Ti(1)-O(2) 152.20(13)
O(4)-Ti(1)-N(2) 169.4(3)
O(3)-Ti(1)-O(4) 100.1(2)
O(1)-Ti(1)-N(2) 86.5(2)
O(2)-Ti(1)-O(1) 156.1(2)
O(4)-Ti(1)-N(1) 164.2(2)
O(1)-Ti(1)-O(1)#1 101.79(18)
O(1)-Ti(1)-N(3) 88.67(12)
O(2)#1-Ti(1)-O(2) 153.06(18)
O(1)-Ti(1)-N(3)#1 167.01(12)
O(4)-Ti(1)-O(3) 101.79(14)
O(3)-Ti(1)-N(2) 88.74(14)
O(1)-Ti(1)-O(2) 156.33(14)
O(3)-Ti(1)-N(1) 166.93(14)
O(2)-Ti(1)-O(3) 101.78(18)
O(4)-Ti(1)-N(1) 85.13(16)
O(4)-Ti(1)-O(1) 153.30(16)
O(2)-Ti(1)-N(2) 166.14(18)
O(1)-Ti(1)-O(2) 101.42(8)
O(3)-Ti(1)-N(1) 84.63(8)
O(4)-Ti(1)-O(3) 152.70(8)
O(2)-Ti(1)-N(1) 165.85(8)
O(3)-Ti(1)-O(7) 104.4(2)
O(2)-Ti(1)-N(1) 86.3(2)
O(2)-Ti(1)-O(1) 155.4(2)
O(7)-Ti(1)-N(2) 164.6(2)
4
OiPr
2.25
1.91
1.82
white
282
5
OtBu
DPE
2.26
1.91
1.81
white
282
7
2.27
1.90
1.82
white
282
8
OPh-Adam
oPP
2.24
1.87
1.88
yellow
yellow
orange
orange
orange
yellow
yellow
yellow
red-orange
red-orange
red-brown
white
281, 336(b)
281, 338(b)
281, 347(b)
282, 356(b)
281, 358(b)
281, 373(b)
281, 327(b)
281, 296(b)
281, 306, 350(b)
281, 313(b), 384(b)
281, 354(vb)
281
10
11
12
13
15
16
17
18
19
20
22
23
24
2.24
1.87
1.85
oBP
2.21
1.88
1.86
DMP
DIP
2.23
1.89
1.87
2.24
1.89
1.86
DPP
2.22
1.89
1.87
2BP
2.25
1.90
1.90
TCP
2.21
1.87
1.89
4MP
4AP
2.22
1.89
1.87
2.24
1.87
1.86
DAP
DMBS
TPS
2.21
1.87
1.85
2.28
1.89
1.82
2.25
1.88
1.85
white
281
TOBS
2.28
1.90
1.84
white
281
1830 Inorganic Chemistry, Vol. 46, No. 5, 2007

Heterocyclic Alkoxy-Modified Titanium Alkoxides
Figure 4. Structure plot of 3. Thermal ellipsoids of heavy atoms drawn
at the 30% level, and carbon atoms represented by ball-and-stick diagrams
for clarity.
Figure 2. Structure plot of 1. Thermal ellipsoids of heavy atoms drawn
at the 30% level, and carbon atoms represented by ball-and-stick diagrams
for clarity.
For compound 1 (Figure 2), a standard edge-shared
bioctahedral (Oh) dinuclear species was isolated. Each metal
center uses three terminal ONep’s and one chelating bridging
(µc-OTHF) ligand to fill its coordination sphere. The µc-
OTHF binding mode of the OTHF is consistent with what
was observed for several other transition metal complexes;
however, these species all contain halide ligands.18,19,25 The
metrical data of 1 are not of sufficient quality to be useful
for further discussion but do establish the connectivity of
the final compound. Structural comparisons are made to the
starting [Ti(µ-ONep)(ONep)3]2,27 the oxygen of the THF-
moiety fills an open coordination site and may display
enhanced reactivity in comparison to [Ti(µ-ONep)(ONep)3]2.
The metrical data for dinuclear 2 are also not of high
enough quality to draw any conclusions, but the general
connectivity is firmly established, see Figure 3. This is the
first OTPM transition metal species reported. Each Ti metal
center is five-coordinated forming what appears to be a
trigonal bipyramidal (TBP) geometry. The OTPM acts only
as a bridging ligand with the soft S atom not binding to the
hard Ti metal center.
Figure 3. Structure plot of 2. Thermal ellipsoids of heavy atoms drawn
at the 30% level, and carbon atoms represented by ball-and-stick diagrams
for clarity.
Using the OPy ligand led to the isolation of a monomeric
species. The strong Lewis basic pyridine moiety of each of
the two OPy ligands binds to the Ti metal centers in a
chelating mode without bridging. The remainder of the
coordination sites in the Oh-bound Ti metal centers were
filled by the two ORs of the starting Ti(OR)4. For transition
metals, numerous species have been crystallized that possess
two OPy’s; however, these ligands are often protonated (H-
OPy),30-41 have bridging OPy ligands,33,42-4545 isolated as
salt derivatives,31,33,35,37,40,43-49 or possess halides.49-52 The
one species of this family that most closely resembles 3 is
metric additions or heating at reflux temperatures for
extended times did not change the products isolated. Crystals
were easily isolated by slow evaporation and the compounds
identified as 1-3, and while not well behaved crystallo-
graphically, the connectivity was unequivocally established
(see Figures 2-4, respectively). Compounds of 1-3 were
then rationally synthesized on the basis of the degree of
substitution noted above for the specific OR* ligands.14-16
[Ti(µ-ONep)(ONep)3]2 + 2nH-OR* f
2 “(OR*)nTi(ONep)4-n” + 2nH-ONep (1)
n ) 1, 2; OR* ) OTHF, OTPM, OPy
(30) Yilmaz, V. T.; Guney, S.; Andac, O.; Harrison, W. T. A. Polyhedron
2002, 21, 2393.
(31) Hamamci, S.; Yilmaz, V. T.; Thone, C. Acta Crystallogr., Sect. E:
Struct. Rep. Online 2004, 60, m6.
(32) Hoang, N. N.; Valach, F.; Dunaj-Jurco, M.; Melnik, M. Acta
Crystallogr. Sect. C: Cryst. Struct. Commun. 1992, 48, 443.
(33) Tesmer, M.; Muller, B.; Vahrenkamp, H. Chem. Commun. 1997, 721.
(34) Yilmaz, V. T.; Guney, S.; Andac, O.; Harrison, W. T. A. Acta
Crystallogr., Sect. C: Cryst. Struct. Commun. 2002, 58, m427.
X-ray Structures. Single-crystal X-ray diffraction studies
were undertaken for 1-3 to initially establish the identity
of these products. Table 1 lists the data collection parameters
of 1-3. Additional structural information can be found in
the Supporting Information.
Inorganic Chemistry, Vol. 46, No. 5, 2007 1831

Boyle et al.
Mo(O)2(OPy)2.53 The isostructural OiPr derivative was
recently reported using CH2Cl2 instead of toluene.28
In order to verify that the bulk material was consistent
with the single-crystal structures noted above for 1-3, the
dried powder was also analyzed by FTIR spectroscopy and
elemental analysis. The FTIR spectrum of each sample
revealed the respective ligand stretches minus the OH stretch.
Further, representative stretches for the neo-pentoxides are
present for 1-3. The strong stretches at 678, 762, and 724
cm-1 for 1-3, respectively, are in the range of the literature
values for Ti-O stretches.1 Combined, these data imply that
the bulk material has OR* ligands that have reacted fully
and are bound to the Ti metal center. Elemental analyses of
the bulk powders of 1-3 were undertaken using crystalline
material and handled under inert atmospheres, and for all
samples, the analyses were consistent with the single-crystal
X-ray structure.
Due to the interest that the disubstituted OPy structure of
3, it was of interest to determine what structures alternative
alkoxides, such as Ti(OiPr)4 or Ti(OtBu)4 (OiPr ) OCH-
(CH3)2 and OtBu ) OC(CH3)3), would yield. The products
isolated from toluene proved to be (OPy)2Ti(OR)2 (OR )
OiPr (4), OtBu (5)).14-16 This substitution clearly demon-
strates the control that the ‘(OPy)2Ti’ moiety can impart to
rational metal alkoxide construction, much like metallocenes
allowed for organometallic species to be synthesized.13 The
structural similarity of these derivatives is surprising with
such varied pendent alkoxides which often lead to different
structures.1-6,13 The metrical data of 3-5 are self-consistent.
Again, IR data reveal the representative alkyl stretches along
with Ti-O stretches at 724, 722, and 720 cm-1 for 3-5,
respectively. Elemental analysis data of the bulk powders
for 3-5 were also found to be in agreement with the single-
crystal data.
Solution Behavior. Dried crystalline materials of 1-5
were re-dissolved in toluene-d8 under an inert atmosphere
at saturated concentrations to explore the solution behavior
of these compounds. Not unexpectedly, the asymmetric
47,49
nature of the ligand set did not allow for a
Ti NMR
1
spectra to be obtained. H NMR data were therefore used
for further investigation of the solution behavior of 1-5.
The 1H NMR spectrum of 1 was found to possess a set of
resonances that were consistent with bound OTHF and ONep
ligands in the 1:3 ratio noted for the solid-state structure.
The peaks are slightly broad, indicating rapid exchange of
the ligands; however, variable-temperature (VT) NMR data
did not show any substantial changes in the spectrum over
a temperature range of -50 to +50 °C. From these data, it
is not possible to determine the nuclearity of 1 in solution;
however, since the crystals formed at room temperature and
there was no significant change in the spectra over a 100 °C
temperature range, it is reasoned that the dinuclear arrange-
ment is favored and most likely retained in solution. [Ti(µ-
ONep)(ONep)3]2 was determined to be monomeric in solu-
tion; however, there were no µc-OR ligands present in this
compound to assist retaining the dinuclear solution noted
for 1.
(35) Christmas, C. A.; Tsai, H.-L.; Pardi, L.; Kesselman, J. M.; Gantzel,
P. K.; Chadha, R. K.; Gatteschi, D.; Harvey, D. F.; Hendrickson, D.
N. J. Am. Chem. Soc. 1993, 115, 12483.
For 2, the OTPM and ONep resonances are sharp, defined,
and clearly observed in the 1:3 ratio except for the methylene
resonances that were slightly broad. This implies there is
little dynamic behavior occurring. VT NMR data (+50 to
-50 °C) revealed no change in the spectrum. The same
reasoning used above for the retention of structure 1 would
apply for 2 and the dinuclear species are believed to be
retained in solution.
(36) Moncol, J.; Mudra, M.; Lonnecke, P.; Koman, M.; Melnik, M. J.
Coord. Chem. 2004, 57, 1065.
(37) Yilmaz, V. T.; Hamamci, S.; Thone, C. Polyhedron 2004, 23, 841.
(38) Bacsa, J.; Zhao, H.; Dunbar, K. R. Acta Crystallogr. Sect. E: Struct.
Rep. Online 2004, 60, m1040.
(39) Moncol, J.; Kalinakova, B.; Svorec, J.; Keleinova, M.; Koman, M.;
Hudecova, D.; Melnik, M.; Mazur, M.; Valko, M. Inorg. Chim. Acta
2004, 357, 3211.
(40) Ito, M.; Onaka, S. Inorg. Chim. Acta 2004, 357, 1039.
(41) He, F.; Liu, D. Acta Crystallogr., Sect. E: Struct. Rep. Online 2005,
61, m1350.
(42) Clemente-Juan, J. M.; Mackiewicz, C.; Verelst, M.; Dahan, F. Inorg.
Chem. 2002, 41, 1478.
(43) Bolcar, M. A.; Aubin, S. M. J.; Folting, K.; Hendrickson, D. N.;
Christou, G. Chem. Commun. 1997, 1485.
(44) Yang, E.-C.; Harden, N.; Wensdorfer, W.; Zakharov, L. N.; Brechin,
E. K.; Rheingold, A. L.; Christou, G.; Hendrickson, D. N. Polyhedron
2003, 22, 1857.
(45) Yoo, J.; Yamaguchi, A.; Nakano, M.; Krzystek, J.; Streib, W. E.;
Brunel, L.-C.; Ishimoto, H.; Christou, G.; Hendrickson, D. N. Inorg.
Chem. 2001, 40, 4604.
(46) Sanudo, E. C.; Brechin, E. K.; Boskovic, C.; Wernsdorfer, W.; Yoo,
J.; Yamaguchi, A.; Concolino, T. R.; Abboud, K. A.; Rheingold, A.
L.; Ishimoto, H.; Hendrickson, D. N.; Christou, G. Polyhedron 2003,
22, 2267.
(47) Harden, N.; Bolcar, M. A.; Wernsdorfer, W.; Abboud, K. A.; Streib,
W. E.; Christou, G. Inorg. Chem. 2003, 42, 7067.
(48) Sanudo, E. C.; Wernsdorfer, W.; Abboud, K. A.; Christou, G. Inorg.
Chem. 2004, 43, 4137.
(49) Martos-Calvente, R.; O’Shea, V. A. P.; Campos-Martin, J. M.; Fierro,
J. L. G.; Gutierrez-Puebla, E. J. Mol. Catal. A: Chem. 2004, 214,
269.
(50) Suzuki, Y.; Tomizawa, H.; Miki, E. Inorg. Chim. Acta 1991, 290, 36.
(51) Rochon, F. D.; Melanson, R.; Kong, P.-C. Inorg. Chim. Acta 1997,
254, 303.
The 1H NMR spectra of 3-5 presented a spectrum wherein
a 1:1 ratio was observed for the OPy/OR (OR ) ONep, Oi-
Pr, OtBu) ligand sets of compounds 3-5, respectively;
however, two types of methylene and OPy resonances were
observed for these samples. In particular, two methylene
resonances were clearly observed for each of these com-
pounds in an ∼1:10 ratio. The diastereotopic methylene
protons of the OPy should be observable but would be
expected to give equal intensities, which these clearly do
not. VT NMR data showed the extra set of OPy resonances
quickly disappeared by 0 °C. Further lowering the temper-
ature did not show any evidence of additional changes except
for selected precipitation of 3-5. The literature NMR data
for 4 in CDCl328 indicated that the OPy ligand was fluctuating
between chelating and terminal; therefore, only one set of
OPy resonances was reported. The diastereotopic methylenes
were reportedly observed at low temperature prior to
precipitation. Therefore, it is not unreasonable to expect in
the less-polar toluene a slightly different solution behavior,
wherein the bound OPy ligand is preferentially present with
(52) Gerber, T. I. A.; Luzipo, D. G.; Mayer, P. J. Chem. Cryst. 2005, 35,
39.
(53) Li, G.; Li, R.-J.; Song, Y.-L.; Xie, L.-X.; Wei, Y.-L.; Fan, Y.-T.; Hou,
H.-W. Huaxue Xuebao (Chin.) (Acta Chim. Sinica) 2002, 60, 1258.
1832 Inorganic Chemistry, Vol. 46, No. 5, 2007

Heterocyclic Alkoxy-Modified Titanium Alkoxides
some degree of fluctionality. This behavior prevents observa-
tion of the diastereotopic methylene protons. The reduced
solubility prevents the identification of these protons at even
slightly reduced temperatures. Combined, these data favor
the retention of the monomeric nature of 3-5 in toluene
solutions and offers an opportunity to rationally construct a
series of (OPy)2Ti(OR)2.
Alcoholysis of (OPy)2Ti(OR)2. In order to verify the
stability of the ‘(OPy)2Ti’ moiety to alcoholysis exchange,
we initiated a series of reactions following eq 2. The alcohol
ligands investigated included alkyl alcohols, aryl alcohols,
substituted aryl alcohols, H-OR*, and silanols. The synthesis
and characterization of these OR* derivatives are discussed
in detail.
Figure 5. Structure plot of 17. Thermal ellipsoids of heavy atoms drawn
at the 30% level, and carbon atoms represented by ball-and-stick diagrams
for clarity.
(OPy)2Ti(OiPr)2 + 2H-OR′ f
“(OPy)2Ti(OR′)2” + 2H-OiPr (2)
OR′ ) OPrMe, OAdam, DPE, OPh-Adam,
oMP, oPP, oBP, DMP, DIP, DBP, DPP, 2BP,
TCP, 4MP, 4AP, DAP, OTPM, DMBS, TPS, TOBS
bulk material was not consistent with the single-crystal
structure wherein the carbon content was consistently lower
than expected. Due to this ambiguity and the lack of
symmetric exchange, we are only reporting the crystal
structure of 6a while we explore the availability of asym-
metric substitution afforded by the isolation of this com-
pound. For the 6b (OAdam) and 9 (oMP) derivatives, crystals
that had elemental analyses consistent with the disubstituted
species were isolated but X-ray quality crystals were not
obtained. For 14, at room temperature, substitution of the
OiPr ligands by the sterically hindering DBP moieties was
not realized even for monosubstitution. Additional studies
are underway to explore and understand the observed
behavior for these compounds.
Synthesis. While all the precursors have demonstrated the
ability to exchange their alkoxide ligands, 4 was selected as
the main starting material for several reasons. Ti(OiPr)4 is
commercially available and less expensive than Ti(OtBu)4
and further, it is the least sterically demanding ligand and
thus more susceptible to exchange. To a stirring solution of
compound 4 in toluene, 2 equiv of the appropriate H-OR′
were added and allowed to stir for 12 h. In case of lower
soluble alcohols, typically the aryloxides, heat was applied
forming highly colored and completely soluble products. For
the polyfunctional aryloxide derivatives, pyridine at elevated
temperatures was required to solubilize these compounds.
FTIR data showed for each sample that the OR′ ligand had
successfully replaced the OR moiety of the starting materials,
based on the lack of an -OH stretch and the presence of
the respective bends and stretches associated with the
particular ligand. In addition, the OPy stretches were also
present in each sample’s spectrum. Preliminarily, this data
suggested that the exchange had been successful.
Elemental analysis was found to be in agreement with the
“(OPy)2Ti(OR′)2” species (7-24). For 7, 15, and 20, the
inclusion of solvent molecules, as noted in their respective
structural solutions (see Table 2), was required for agreement;
however, 17 (lattice solvent removed by the squeeze program
of the PLATON software package) and 19 did not require
the structurally characterized lattice solvent molecule for
agreement. For 8 and 11, a molecule of toluene needed to
be added to the molecular formula that is consistent with
the toluene solvent molecule that was removed by the
squeeze program in the final refinement of the structure.
Compounds 6 and 14 did not agree completely with expected
disubstituted compounds and were not self-consistent during
analysis. Attempts to synthesize the disubstituted species
(OPy)2Ti(OPrMe)2 (6), under room-temperature conditions,
led to a heteroligated species instead, forming the (OPy)2Ti-
(OiPr)(OPrMe) (6a) derivative. The elemental analysis of the
1
The H NMR data of 7-24 (14 was omitted from the
study) demonstrated similar behavior as noted above for 3-5.
Combined, these data indicate that the ‘(OPy)2Ti’ moiety
has been retained. In order to verify this claim, the structure
of each compound was determined.
Crystal Structures. The following species were investi-
gated structurally as (OPy)2Ti(OR′)2: OR′ ) DPE (7), OPh-
Adam (8), oPP (10), oBP (11), DMP (12), DIP (13), DPP
(15), 2BP (16), TCP (17), 4MP (18), 4AP (19), DAP (20),
OTPM (21), DMBS (22), TPS (23), and TOBS (24). Table
2 lists the collection data for each of these compounds. Table
3 lists the compounds and their respective alcohols. Figures
5-7 are representative species (17, 21, 24) of the resultant
chemistry (8 is shown in the Table of Contents figure).
Since the initial OPrMe reaction formed 6a and not the
desired disubstituted species, it was of interest to determine
what factors would control the exchange, and therefore,
additional sterically varied alcohols were investigated. For
the OAdam (6b) and DPE (7) ligand sets, analytical data
(FTIR and elemental analysis) were consistent with the
disubstitution product. For each, NMR data were also
consistent with the monomeric disubstituted species. While
7 was easily isolated in crystalline form and structurally
characterized as the disubstituted species, all attempts to get
Inorganic Chemistry, Vol. 46, No. 5, 2007 1833

Boyle et al.
moiety remained intact for all the alcohols investigated
including a derivative that contained the adamantane moiety
(OAdam-Ph, 8, see Table of Contents figure), mono- and
dialkyl ortho-substituted phenoxide derivatives (9-13), and
phenyl-substituted species (15). Even more complex ary-
loxides (16-21) did not yield any variations in the ‘(OPy)2Ti’
moiety upon exchange. This was surprising since the amine-
substituted compounds (19 and 20) could only be dissolved
in boiling pyridine but there was no evidence of coordinating
solvent. This is most likely a reflection of the stable nature
of the bidentate OPy ligands preventing additional Lewis
base coordination. Substitution by the other OR* ligand only
produced a terminal OTPM set of ligands (21) similar to
what was noted for 2 in terms of the binding mode. Full
substitution by the OPy ligand or modification by the OTHF
derivatives did not yield crystalline material. Switching to
silanols presented a slightly different electronic and steric
ligand set, but again the ‘(OPy)2Ti’ moiety was unaffected
by any silanol substitution 22-23. A slight variation with
an alkoxy siloxide ligand, TOBS that would provide a more
electron-withdrawing effect, also retained the basic structural
motif (24). As can be observed from this unusually stable
family of compounds, exchange was readily realized without
destruction of the stabilizing moiety; therefore, we have
developed a scaffold from which controlled metal alkoxides
can be systematically built. The metrical data for 3-24 are
comparable with surprisingly little variation noted by the
presence of the substituted alkoxide ligand (see Table 3).
UV-vis spectra were obtained for 3-24 in toluene (see
Table 3) in an attempt to understand the color variations
noted for these compounds. The light brown H-OPy was
found to have one large absorption at λmax 281 nm attributed
to the py ring of the OPy compound. A stretch consistent
with the OPy ligand was observed in every sample ranging
from λmax 281 to 283 nm. For the colored species (8-20),
several additional broad peaks at higher energies were noted
ranging from λmax 296 to 384 nm. The color variations from
yellow to orange are paralleled by shifts in the second
absorption peaks. The mixed-color species either have two
peaks in addition to the OPy ligand absorptions (18-19) or
a very broad peak (20) that covers the same regions. It is
obvious from this study that the aromatic ligands, not the
OPy ligands, are imparting a ligand-to-metal charge transfer
to produce the observed colors for these compounds. Further,
the emission color can be fine-tuned on the basis of the
substitution of the ring or the number and types of ligands
present on the ‘(OPy)2Ti’ moiety.
Figure 6. Structure plot of 21. Thermal ellipsoids of heavy atoms drawn
at the 30% level, and carbon atoms represented by ball-and-stick diagrams
for clarity.
Figure 7. Structure plot of 24. Thermal ellipsoids of heavy atoms drawn
at the 30% level, and carbon atoms represented by ball-and-stick diagrams
for clarity.
crystallographic data on 6b were unsuccessful. This led us
to explore the more rigid and sterically varied aryloxides.
In most of the M(OR)x systems that we have explored,
aryloxides offer significant variation in structural complexity
in comparison to alkyl alkoxides;9,54-56 therefore, we were
interested in the effect these large ligands would have on
this system. For all of the aromatic species, the color of the
resultant crystals were a bright orange to yellow, based on
the specific ligand. The color variations were presumed to
be from ligand to metal charge transfer as determined by
the UV-vis spectra collected (vide infra). The ‘(OPy)2Ti’
Summary and Conclusion
Using the OR* ligands (OTHF, OTPM, and OPy), a new
family of heterocyclic alkoxides have been isolated as 1-5.
For the OTHF- and OTPM-ligated species, monosubstituted
dinuclear compounds were isolated with the ligand acting
either as a µc-OR or as a µ-OR ligand, respectively; for the
OPy, disubstituted chelating ligation was observed. It appears
from solution NMR data that these structures are retained
in solution. Due to the steric constraints imparted by the
disubstituted OPy ligated species with a variety of sterically
(54) Boyle, T. J.; Andrews, N. L.; Rodriguez, M. A.; Campana, C.; Yiu,
T. Inorg. Chem. 2003, 42, 5357.
(55) Boyle, T. J.; Bunge, S. D.; Andrews, N. L.; Matzen, L. E.; Sieg, K.;
Rodriguez, M. A.; Headley, T. J. Chem. Mater. 2004, 16, 3279.
(56) Boyle, T. J.; Pedrotty, D. M.; Alam, T. M.; Vick, S. C.; Rodriguez,
M. A. Inorg. Chem. 2000, 39, 5133-5146.
1834 Inorganic Chemistry, Vol. 46, No. 5, 2007

Heterocyclic Alkoxy-Modified Titanium Alkoxides
hindering OR groups, the opportunity to pursue controlled
chemistry of metal alkoxides is readily available. The
‘(OPy)2Ti’ moiety is reminiscent of metallocene derivatives
‘(Cp)2Ti’ moieties wherein the Cp ligands protect one side
of the metal center and allow for controlled chemistries to
be carried out on the opposite side. We have for the first
time clearly demonstrated the utility of the ‘(OPy)2Ti’ moiety
as a useful stable building block for a number of complex
structures (6-24), each of which surprisingly do not disrupt
this moiety. This allows for the first time controlled
modifications of Ti(OR)4 leading to predictable structures.
Currently, several metal systems and carboxylate systems
are under investigation to determine the extent of this
reactivity and to control the properties of the ‘(OPy)2Ti’
scaffold.
Acknowledgment. The authors thank Prof. A. L. Rhei-
ngold (UCSD) for helpful discussions and for support of this
research, the Office of Basic Energy Sciences, and the U.S.
Department of Energy under Contract No. DE-AC04-
94AL85000. Sandia is a multiprogram laboratory operated
by Sandia Corporation, a Lockheed Martin Company, for
the United States Department of Energy.
Supporting Information Available: Crystallographic data in
CIF format. This material is available free of charge via the Internet
at http://pubs.acs.org.
IC0618798
Inorganic Chemistry, Vol. 46, No. 5, 2007 1835