On the reactions of bisdiolatotungsten(VI) phenoxides. Syntheses, characterizations, and molecular structures of trans-[WCl2(Diol)(OAr)2]

Article abstract of DOI:10.1021/ic010583t

Coordinated phenoxide groups in [W(eg)₂(mephe)₂] (2a) and [W(eg)₂(prphe)₂] (2c) (eg = ethanediolate dianion; mephe = OC₆H₃Me₂-2,6; prphe = OC₆H₃ⁱPr₂-2,6) undergo reaction with Br₂, leading to substitution at the para position of the phenyl rings and formation of the complexes [W(eg)₂(OC₆H₂R₂-2,6-Br-4) ₂] (2b, R = Me; 2d, R = ⁱPr). The reaction of complexes 2a-2d and [W(eg)₂(buphe)₂] (2e) (buphe = OC₆H₃tBu₂-2,4) with HCl leads to the displacement of one bidentate diolato ligand from the complex unit and formation of the corresponding trans dichloro diolato bis(phenoxide) tungsten(VI) complex [WCl₂(eg)(OAr)₂] (3). The X-ray crystal structure determinations of these compounds confirmed that all complexes 3 have a similar gross structure in which the chloro ligands are arranged at trans positions.

Full text of DOI:10.1021/ic010583t

Inorg. Chem. 2001, 40, 6047-6051
6047
On the Reactions of Bisdiolatotungsten(VI) Phenoxides. Syntheses, Characterizations, and
Molecular Structures of trans-[WCl2(Diol)(OAr)2]
Ari Lehtonen* and Reijo Sillanpa1a1
Department of Chemistry, University of Turku, FIN-20014, Turku, Finland
ReceiVed June 4, 2001
Coordinated phenoxide groups in [W(eg)2(mephe)2] (2a) and [W(eg)2(prphe)2] (2c) (eg ) ethanediolate dianion;
i
mephe ) OC6H3Me2-2,6; prphe ) OC6H3 Pr2-2,6) undergo reaction with Br2, leading to substitution at the para
position of the phenyl rings and formation of the complexes [W(eg)2(OC6H2R2-2,6-Br-4)2] (2b, R ) Me; 2d, R
i
) Pr). The reaction of complexes 2a-2d and [W(eg)2(buphe)2] (2e) (buphe ) OC6H3tBu2-2,4) with HCl leads
to the displacement of one bidentate diolato ligand from the complex unit and formation of the corresponding
trans dichloro diolato bis(phenoxide) tungsten(VI) complex [WCl2(eg)(OAr)2] (3). The X-ray crystal structure
determinations of these compounds confirmed that all complexes 3 have a similar gross structure in which the
chloro ligands are arranged at trans positions.
Introduction
Complexes 3 are the first examples of tungsten(VI) alkoxide
phenoxides which carry a trans-dichloro moiety. Furthermore,
bromination of the coordinated phenoxide group in the com-
plexes 2 was also studied as an example of aromatic substitution
in a ligand. Our long-term goal is to employ these functionalities
in the preparation of polymer- or silica-supported tungsten
catalysts.
Early transition metal alkoxides have been widely studied
due to their applications in organometallic and catalytic
chemistry, and a number of these studies have been stimulated
by the demonstrated ability of various tungsten compounds
containing alkoxide and aryloxide ligands to catalyze metathesis
reactions of cyclic and acyclic alkenes.1-5 For example, tungsten
phenoxides of the type [WCl6-x(OAr)x] and [WOCl4-y(OAr)y]
are used as precursors for two-component catalyst systems,
typically in the presence of an organometallic activator.2 A
standard procedure for the preparation of these complexes is
the reaction of WCl6 or WOCl4 with a phenolic compound,
which often results in a mixture of species with varying numbers
of phenoxide substituents, some of which may also carry
positional isomers with respect to the tungsten center.6,7 Previ-
ously, we reacted [W(eg)3] (1) (eg ) 1,2-ethanediolate dianion)
with substituted phenyl acetates to prepare heteroleptic W(VI)
phenoxides of the type [W(eg)2(OAr)2] (2) and have used these
complexes as catalyst precursors in a two-component system
for the ring opening metathesis polymerization of dicyclopen-
tadiene and norbornene.8,9 To attain a greater degree of un-
derstanding of the chemistry of these complexes, we have now
examined chloride-for-alkoxide substitution and prepared com-
plexes of the type [WCl2(eg)(OAr)2] (3) by treating 2 with HCl.
Experimental Section
General Information. Solvents were dried over CaH2 and distilled
prior to use. Other chemicals were of reagent grade and used as
purchased. Complexes 1, 2a, 2c, and 2e were prepared according to
the literature procedures.8,9 1H NMR spectra were recorded using a
Bruker AM 200 spectrometer in CDCl3 solutions and were referenced
internally to SiMe4. IR spectra were recorded as KBr disks, using a
Mattson Galaxy FTIR spectrometer. Elemental analyses were obtained
using a Perkin-Elmer CHNS-Analyzer 2400. Analytical samples were
dried in vacuo at 40 °C for 2 h prior to elemental and spectral analyses.
Bromination of 2a and 2c. To a solution of 2a or 2c (0.20 mmol,
110 mg or 130 mg, respectively) in CCl4 (10 mL) was added Et3N
(1.0 mmol, 0.14 mL) and Br2 (0.50 mmol, 25 µl) at room temperature.
The reaction mixture was stirred for 2 h, filtered, and dried under
reduced pressure. The yellow, solid crude product was purified by
column chromatography using CH2Cl2 as eluent. 2b and 2d were also
prepared from 1 and the appropriate phenyl acetates using literature
methods.9
[W(eg)2(OC6H2Me2-2,6-Br-4)2] (2b). Yield, 120 mg (85%). 1H
NMR (CDCl3): δ 7.15 (4H, s, aromatics), 5.50 (2H, m, CH2), 5.30
(6H, m, CH2), 2.45 (12H, s, CH3). IR (KBr): 1469 vs, 1380 vs, 1360
w, 1320 w, 1269 s, 1200 vs (br), 1070 vs (br), 1005 w, 930 s, 905 s,
900 s, 860 s, 850 m, 794 vs, 725 m, 652 s, 625 vs, 580 m, 568 s, 560
m, 525 s, 444 m, 415 w cm-1. Anal. Calcd for C20H24Br2O6W: C,
34.1; H, 3.4. Found: C, 34.3; H, 3.4.
[W(eg)2(OC6H2iPr2-2,6-Br-4)2] (2d). Yield, 145 mg (89%). 1H NMR
(CDCl3): δ: 7.16 (4H, s, aromatics), 5.55 (2H, m, CH2), 5.30 (6H, m,
CH2), 3.60 (4H, m, CHMe2), 1.18 (24H, s, CH3). IR (KBr): 1470 vs,
1385 vs, 1360 w, 1340 w, 1320 w, 1270 w, 1200 vs (br), 1070 vs (br),
1005 w, 990 w, 930 s, 905 s, 900 s, 860 s, 850 m, 795 vs, 725 m, 650
s, 625 vs, 580 m, 568 s, 560 m, 525 s, 442 m, 415 w cm-1. Anal.
Calcd for C28H40Br2O6W: C, 41.2; H, 4.9. Found: C, 41.0; H, 4.8.
General Procedure for the Syntheses of 3a-3e. To a solution of
2 (0.250 mmol) in CH2Cl2 (20 mL) was introduced a slow stream of
* To whom correspondence should be addressed. Telefax:+358-2-
3336700. E-mail: ari.lehtonen@utu.fi.
(1) Mayer, J. M. Polyhedron 1995, 14, 3273-3292.
(2) Ivin, K. J.; Mol, J. C. Olefin Metathesis and Metathesis Polymerization;
Academic Press: London, 1997.
(3) Lefebvre, F.; Leconte, M.; Pagano, S.; Mutch, A.; Basset, J.-M.
Polyhedron 1995, 14, 3209-3226.
(4) Go´mez, F. J.; Abboud, K. A.; Wagener, K. B. J. Mol. Catal. A: Chem.
1998, 133, 159-166. (b) Go´mez, F. J.; Manak, M. S.; Abboud, K.
A.; Wagener, K. B. J. Mol. Catal. A: Chem. 2000, 160, 145-156.
(5) Kelsey, D. R.; Handlin, D. L.; Narayana, M.; Scardino, B. M. J. Polym.
Sci. A: Polym. Chem. 1997, 35, 3027-3047.
(6) Quignard, F.; Leconte, M.; Basset, J.-M.; Hsu, L.-Y.; Alexander, J.
J.; Shore, S. G. Inorg. Chem. 1987, 26, 4272-4277.
(7) Nugent, W. A.; Feldman, J.; Calabrese, J. C. J. Am. Chem. Soc. 1995,
117, 8992-8998.
(8) Lehtonen, A.; Sillanpa¨a¨, R. Polyhedron 1999, 18, 175-179.
(9) Lehtonen, A.; Sillanpa¨a¨, R. Inorg. Chem. Commun. 2001, 4, 108-
110.
10.1021/ic010583t CCC: $20.00 © 2001 American Chemical Society
Published on Web 10/03/2001

6048 Inorganic Chemistry, Vol. 40, No. 23, 2001
Table 1. Crystallographic Data for Compounds 3
Lehtonen and Sillanpa¨a¨
3a′
3a′′
3b
3c′
3c′′
3e
formula
Mr
cryst syst
space group (no.)
a/Å
b/Å
c/Å
C18H22Cl2O4W
557.11
triclinic
C18H22Cl2O4W
557.11
triclinic
P-1 (2)
8.391(4)
15.909(6)
8.117(4)
109.50(4)
109.50(4)
87.03(4)
997.8(7)
2
1.854
6.075
3498
0.0399
226
0.074 (0.033)
0.087 (0.075)
C18H20Br2Cl2O4W
714.91
C26H38Cl2O4W
669.31
monoclinic
P21 (4)
9.712(2)
10.0849(14)
14.7712(16)
90
90.437(13)
90
1446.8(4)
2
1.536
4.204
2700
C26H38Cl2O4W
669.31
C30H46Cl2O4W
725.42
orthorhombic
Pbca (60)
22.506(3)
27.700(6)
10.729(2)
90
90
90
6689(2)
8
1.441
3.643
5892
-
328
0.201 (0.053)
0.123 (0.093)
monoclinic
C2/c (15)
24.634(3)
11.508(4)
16.465(2)
90
101.295(13)
90
4577.1(17)
8
2.075
8.793
4028
0.0229
tetragonal
I-4 (82)
26.657(6)
26.657(6)
10.304(10)
90
90
90
7322(7)
8
1.214
3.322
3552
0.0456
298
0.1162 (0.0521)
0.1385 (0.1188)
P-1 (2)
11.3504(14)
11.3636(10)
8.3205(11)
104.248(8)
94.583(12)
73.150(9)
995.5(2)
2
1.859
6.089
3510
0.0187
R/°
â/°
γ/°
U/Å3
Z
Dc/g cm-1
µ(Mo KR)/mm-1
obs. reflns
Rint
0.0181
299
0.038 (0.027)
0.057 (0.055)
parameters
226
0.049 (0.031)
0.064 (0.060)
244
0.121 (0.043)
0.094 (0.078)
R1a
wR2a
a Values in parentheses for reflections with I > 2.0σ(I). R1 ) ∑ | |Fo| - |Fc| |/∑ |Fo|, wR2 ) {∑[w(Fo - Fc2)2]/∑[w(Fo )2]}1/2, and w )
2
2
1/[σ2(Fo ) + (aP)2 + bP)], where P ) (2Fc2 + Fo )/3.
2
2
Scheme 1. Bromination of Coordinated Phenoxide in 2
dry, gaseous HCl for 5 min, resulting in the solution changing from
yellow to red in color. The mixture was allowed to stand at room
temperature for 2 h (8 h were required for 3c and 3d). By TLC (silica
gel using CH2Cl2 eluent), one major component and trace amounts of
other components were present. Volatiles were then removed under
reduced pressure, and the dark-red residue was column chromatographed
over silica gel using CH2Cl2 as eluent. Crystals for X-ray measurements
were grown from acetonitrile (3a′, 3c′, and 3e) or hexane (3a′′, 3b,
and 3c′′) solutions. IR spectra for compounds 3a and 3c were measured
on crystals obtained from hexane.
1
[W(eg)(OC6H2Me2-2,6)2Cl2] (3a). Yield, 53 mg (39%). H NMR
(CDCl3): δ 7.12 (2H, s, aromatics), 7.08 (2H, s, aromatics), 6.85 (2H,
m, aromatics), 5.93 (4H, m, CH2), 2.69 (12H, s, CH3). IR (KBr): 1468
s, 1450 m, 1380 w, 1320 m, 1300 w, 1279 m, 1200 vs, 1190 vs, 1088
s, 1037 vs, 1015 m, 914 vs, 788 s, 768 vs, 734 s, 725 m, 651 vs, 625
w, 575 m, 543 s, 426 m. Anal. Calcd for C18H22Cl2O4W: C, 38.8; H,
4.0. Found: C, 38.9; H, 4.2.
415 w cm-1. Anal. Calcd for C30H46Cl2O4W: C, 49.7; H, 6.4. Found:
C, 49.6; H, 6.2.
X-ray Crystal Determinations. Crystal data for all compounds
along with other experimental details are summarized in Table 1. Single-
crystal data collections, reduction, and subsequent calculations were
performed essentially as described the previous papers.8 Three of the
four tert-butyl groups in 3e were refined in two positions.
[W(eg)(OC6H2Me2-2,6-Br-4)2Cl2] (3b). Yield, 82 mg (46%). 1H
NMR (CDCl3): δ 7.17 (2H, s, aromatics), 7.13 (2H, s, aromatics), 5.90
(4H, m, CH2), 2.70 (12H, s, CH3). IR (KBr) 1470 s, 1450 m, 1380 w,
1320 m, 1300 w, 1280 m, 1200 vs, 1190 vs, 1088 s, 1035 vs, 1015 m,
912 vs, 788 s, 768 vs, 734 s, 725 m, 650 vs, 625 w, 575 m, 545 s, 425
m cm-1. Anal. Calcd for C18H20Br2Cl2O4W: C, 30.2; H, 2.8. Found:
C, 30.0; H, 2.8.
Results and Discussion
Reactions. The coordinated phenoxide group can readily
undergo some substitution reactions typical of the free ligands,
e.g., [W(OPh)6] is known to react in CCl4 solution with bromine
in the presence of CaCO3 to form [W(OPh-4-Br)6] in practically
quantitative yield.10 Thus, treatment of either bisdiolato complex
2a or 2c with Br2 in CCl4 produced the analogous complex 2b
or 2d, respectively, with para-brominated phenoxide groups in
nearly quantitative yields (see Scheme 1). These bromophe-
noxides may be further derivatized to prepare building blocks
for polymer- or silica-supported tungsten complexes. The
presence of base is essential in this reaction (e.g., triethylamine)
as otherwise a mixture of several products is obtained, resulting
in lower yields and the requirement for a more extensive
purification process. In the absence of a base, the liberated HBr
from the reaction apparently results in (according to TLC and
NMR analyses) the bromo analogue of 3 (see below).
i
1
[W(eg)(OC6H3 Pr2-2,6)2Cl2] (3c). Yield, 32 mg (19%). H NMR
(CDCl3): δ 7.28 (2H, s, aromatics), 7.24 (2H, s, aromatics), 7.05 (2H,
m, aromatics), 5.90 (4H, m, CH2), 3.93 (4H, m, CHMe2), 1.26 (24H,
m, CH3). IR (KBr) 1461 s, 1430 m, 1380 m, 1360 m, 1322 s, 1245 s,
1200 s, 1174 vs, 1155 m, 1103 s, 1041 vs, 1016 w, 913 vs, 885 m, 823
w, 803 s, 788 s, 750 vs, 715 s, 655 vs, 625 w, 607 s, 545 vs, 445 w,
431 m, 426 m cm-1. Anal. Calcd for C26H38Cl2O4W: C, 46.7; H, 5.7.
Found: C, 46.5; H, 5.8.
[W(eg)(OC6H2 Pr2-2,6-Br-4)2Cl2] (3d). Yield, 60 mg (29%). 1H
i
NMR (CDCl3): δ 7.27 (2H, s, aromatics), 7.23 (2H, s, aromatics), 5.90
(4H, m, CH2), 3.95 (4H, m, CHMe2), 1.25 (24H, m, CH3). IR (KBr)
1465 s, 1430 m, 1382 m, 1360 m, 1320 s, 1245 s, 1203 s, 1174 vs,
1155 m, 1103 s, 1041 vs, 1016 w, 911 vs, 885 m, 823 w, 803 s, 785
s, 750 vs, 715 s, 655 vs, 625 w, 607 s, 544 vs, 445 w, 431 m, 426 m
cm-1. Anal. Calcd for C26H36Br2Cl2O4W: C, 37.8; H, 4.4. Found: C,
38.0; H, 4.5.
t
1
[W(eg)(OC6H3 Bu2-2,4)2Cl2] (3e). Yield, 130 mg (72%). H NMR
(CDCl3): δ 7.74 (1H, s, aromatics), 7.70 (1H, s, aromatics), 7.43 (4H,
m, aromatics), 5.92 (4H, m, CH2), 1.49 (18H, s, CH3), 1.33 (18H, s,
CH3). IR (KBr) 1481 vs, 1461 s, 1430 m, 1390 m, 1361 s, 1322 m,
1300 m, 1270 w, 1245 s, 1215 vs, 1200 s, 1164 m, 1125 s, 1085 vs,
1046 vs, 1025 w, 917 vs, 885 m, 867 vs, 824 s, 759 s, 728 m, 759 s,
725 w, 665 vs, 625 w, 597 vs, 565 s, 537 vs, 445 w, 430 m, 425 w,
Metal alkoxides can be transformed into mixed-ligand
complexes composed of alkoxides and halides by various
substitution reactions.11 The direct addition of anhydrous HCl
is the most straightforward method to the stepwise substitution
(10) Mortimer, I. P.; Strong, M. I. Aust. J. Chem. 1965, 18, 1579-1587.

Reactions of Bisdiolatotungsten(VI) Phenoxides
Inorganic Chemistry, Vol. 40, No. 23, 2001 6049
Scheme 2. Chloride-for-alkoxide Substitution of 2
Figure 1. The ORTEP20 drawing of complex [WCl2(eg)(mephe)2] (3a′)
showing 30% probability ellipsoids. The hydrogen atoms have been
omitted for clarity. The crystals were grown from acetonitrile.
of alkoxides but can be difficult to control.12 Other successful
reagents include AcOX, Me3SiX, SOX2, and AlX3 (X ) F, Cl,
Br), where the reagent can react with proton sources, e.g., trace
amounts of alcohol forming HX, the actual reacting species.13-15
Compounds of type 2 were successfully reacted directly with
HCl in this study to yield dichlorocomplexes of type 3, as
indicated in Scheme 2.
The yellow-orange dichloromethane solutions of 2 were
saturated with dry HCl forming intense red solutions, which
were allowed to stand at room temperature for a few hours.
Complexes 2c and 2d, which are substituted at both the 2 and
6 positions by bulky iso-propyl groups, required longer reaction
times to produce notable yields. Significantly, 2e reacted without
difficulty, implying that steric hindrance is the reason and not
inductive effects. Also, the best yield was achieved by 2e. In
all cases, purification by column chromatography was required
to yield compounds 3 as dark-red crystalline solids. Complexes
3 are stable in air at room temperature and are very soluble in
hydrocarbons, acetonitrile, chlorinated solvents, and ethers. They
are also soluble in alcohols but decompose slowly in alcohol
solutions. Identical products (by TLC and NMR) were also
formed from the reactions of 2 with other chloride sources, e.g.,
AlCl3, AcOCl, or SOCl2, but the yields were lower due to the
formation of many side-products which, moreover, made
purification of the products more difficult. NMR and X-ray
analysis of 3 verified that one eg ligand is displaced from 2
and replaced by two chlorides. This substitution results in the
substantial rearrangement of the ligands, as the two newly
introduced chlorides are oriented trans to one another but have
replaced two oxygen atoms of one eg ligand which are, by
necessity, in cis positions. The substitution reaction was shown
to be reversible, as complexes 3 react with H2eg in the presence
of base to reform 2, which indicates that the coordination sphere
around W(VI) is quite flexible. Our attempts to eliminate the
second eg ligand and prepare tetrachlorides of type [WCl4-
(OAr)2] by continuing the reaction further were unsuccessful.
The prolonged treatment of complexes 2 with any of the
abovementioned chloride sources did not result in the desired
compound and only led finally to the formation of an unchar-
acterized dark solid and free phenol.
Figure 2. The ORTEP20 drawing of complex [WCl2(eg)(Brmephe)2]
(3b) showing 30% probability ellipsoids. The hydrogen atoms have
been omitted for clarity. The crystals were grown from hexane.
1
1H NMR Studies. The H NMR spectra of compounds 2b
and 2d showed the typical resonances for substituted phenolato
ligands. In the aliphatic region of the spectra, two distinct
multiplets for the ethanediolate groups are observed (at ca. 5.3
and 5.5 ppm), implying that there are two different environments
for these methylene protons. These portions of the spectra for
the eg ligands are similar to the previously reported spectra of
comparable complexes, e.g., [W(bino)(eg)2] (bino ) 1,1′-bi-2-
naphtholate).16 In the case of complexes 3, the 1H NMR spectra
also showed typical resonances for the phenolato ligands but
only one multiplet for the eg group (at ca. 5.9 ppm). In principle,
the unsymmetrical phenolato ligands (buphe) in complex 3e can
adopt either of two different rotational isomers (syn and anti),
which are similar to the imido ligand in the structurally
comparable molybdenum bis imido complex [MoCl2(dme)(NPht-
1
Bu-2)2].17 However, the H NMR spectrum of 3e in CDCl3 at
t
room temperature contained only one signal for Bu groups in
the ortho position. Thus, on the NMR time-scale in solution at
room temperature they are time averaged and yield only one
signal. X-ray structure determination of 3e verified that these
asymmetric phenolato ligands adopted a syn conformation in
the solid state (see below).
X-ray Crystal Structures. Compounds 3a-3c and 3e form
monomeric molecules in which one diolato ligand (two oxygen
donors), two phenolato oxygen atoms, and two chloro ligands
bond to the central tungsten atom (Figures 1 -4). The main
features of the structures are the following: 1) the chloro ligands
are in trans positions relative to one another (the Cl-W-Cl
angle is ca. 180°), 2) the O(diolato)-W-O(diolato) angle is
79°, and 3) the O(phenolato)-W-O(phenolato) angle is about
100°. The distorted octahedral trans-WCl2O4 units are generally
similar in all studied compounds, as indicated by the bond
parameters presented in Table 2. The phenyl groups can adopt
(11) Chisholm, M. H.; Rothwell, I. P. In ComprehensiVe Coordination
Chemistry; Wilkinson, G., Gillard, R. D., McCleverty, J. A., Eds.;
Pergamon: New York, 1987; Vol. 2, Chapter 15.3, pp 335-364.
(12) Crans, D. C.; Chen, H.; Felty, R. A. J. Am. Chem. Soc. 1992, 114,
4543-4550.
(13) Chisholm, M. H.; Clark, D. L.; Errington, R. J.; Folting, K.; Huffman,
J. C. Inorg. Chem. 1988, 27, 2071-2084.
(14) Xu, B.; Carroll, P. C.; Swager, T. M. Angew. Chem., Int. Ed. Engl.
1996, 35, 2094-2097.
(16) Lehtonen, A.; Sillanpa¨a¨, R. Polyhedron 2000, 19, 2579-2584.
(17) Nielson, A. J.; Glenny, M. W.; Rickard, C. E. F.; Waters, J. M. J.
Chem. Soc., Dalton Trans. 2000, 4569-4578.
(15) Lehtonen, A.; Sillanpa¨a¨, R. Polyhedron 1995, 14, 455-457.

6050 Inorganic Chemistry, Vol. 40, No. 23, 2001
Lehtonen and Sillanpa¨a¨
Table 2. Selected Bond Distances (Å) and Angles (deg) for Complexes 3
3a′
3a′′
3b
3c′
3c′′
3e
W-O(1)
1.880(4)
1.888(4)
1.840(4)
1.847(4)
2.358(2)
2.398(2)
1.380(6)
1.379(6)
79.13(16)
169.92(17)
88.92(16)
91.85(17)
168.02(16)
100.14(17)
178.27(6)
166.0(4)
167.4(4)
29.6(7)
1.886(6)
1.877(6)
1.849(5)
1.841(6)
2.363(3)
2.388(3)
1.371(9)
1.379(10)
78.9(3)
170.6(3)
89.2(3)
93.5(3)
167.6(3)
98.6(3)
177.12(11)
159.6(5)
165.6(6)
35(1)
1.884(7)
1.876(7)
1.862(7)
1.849(7)
2.357(3)
2.371(3)
1.362(11)
1.365(11)
79.5(3)
169.5(3)
90.9(3)
90.8(3)
169.9(3)
99.0(3)
179.25(13)
157.0(6)
156.8(7)
29(2)
1.877(6)
1.873(6)
1.845(5)
1.874(5)
2.367(3)
2.354(3)
1.371(9)
1.380(10)
79.5(3)
172.9(3)
87.9(3)
93.4(3)
166.7(3)
99.2(3)
177.79(12)
172.3(6)
147.6(5)
18(2)
1.886(11)
1.880(11)
1.846(12)
1.842(12)
2.359(5)
2.385(5)
1.41(2)
1.42(2)
79.4(5)
170.7(6)
87.3(5)
92.2(6)
166.7(5)
101.1(5)
177.2(2)
158.0(11)
159.0(11)
-18(3)
38.7(4)
50.3(6)
88.5(6)
5.56(4)
1.869(8)
1.881(8)
1.857(8)
1.857(8)
2.362(3)
2.365(3)
1.398(13)
1.366(12)
78.6(3)
166.5(3)
88.0(3)
89.0(3)
165.4(3)
104.9(3)
175.76(12)
146.6(8)
147.2(7)
16(2)
W-O(2)
W-O(3)
W-O(4)
W-Cl(1)
W-Cl(2)
O(3)-C(3)
O(4)-C(Ar)
O(1)-W-O(2)
O(1)-W-O(3)
O(1)-W-O(4)
O(2)-W-O(3)
O(2)-W-O(4)
O(3)-W-O(4)
Cl(1)-W-Cl(2)
C(3)-O(3)-W
C(Ar)-O(4)-W
O1-C1-C2-O2
a
O4 vs τ1
29.4(2)
38.9(2)
65.4(2)
4.02(1)
30.9(3)
43.5(3)
74.1(3)
3.86(2)
40.8(3)
44.2(3)
84.9(3)
4.47(2)
28.3(4)
60.3(3)
86.9(3)
5.61(2)
23.5(4)
22.2(5)
42.9(4)
7.25(2)
a
O4 vs τ2
a
τ1 vs τ2
C(me)‚‚‚C(me)b
a The dihedral angle between the O4 coordination plane and the phenyl ring bonded to O(3) (τ1); τ2 is the plane of the phenyl ring bonded to
O(4). b The closest distance between the two central carbon atoms of the substituents located at the ortho positions of adjacent phenyl rings.
structure. The material is also quite soft and only poorly reflects
the X-rays. The small residual electron density (0.80 e/Å3) and
the poor quality of the data did not permit the refinement of
any possible hexane molecules within the cavities of the
structure. The packing efficiency of 3c′ is much greater than
that of 3c′′, as the calculated density (Dc) for the former is 1.536
g cm-3 and the latter is 1.214 g cm-3, so the latter contains
21% more empty space than the former. The main differences
between the two crystal forms of 3a and 3c are in the
orientations of the phenyl rings, which is due to the packing
forces. This also resulted in small changes in the bond
parameters on the coordination sphere.
Figure 3. The ORTEP20 drawing of complex [WCl2(eg)(prphe)2] (3c′)-
showing 30% probability ellipsoids. The hydrogen atoms have been
omitted for clarity. The crystals were grown from acetonitrile.
From the bond parameters presented in Table 2, it is seen
that the W-O(diolato) bond lengths in 3a-c,e vary from
1.869(8) to 1.888(4) Å, while the W-O(phenolato) bond
lengths vary from 1.840(4) to 1.874(5) Å, i.e., the W-O-
(diolato) bond lengths are slightly longer than the W-O(phe-
nolato) bond lengths. The trans-O(diolato)-W-O(phenolato)
angles vary from 165.4(3) to 172.9(3)°. The smallest trans-
O-W-O angle is present in 3e where, in concert, the largest
bond angle for the cis-phenolato ligands is observed (for 3e
the O(3)-W-O(4) bond angle is 104.9(3)°, for these other
compounds it is ca. 100°). This suggests that the two bulky
ArO- ligands slightly distort the coordination sphere of the
WCl2(eg)(ArO)2 unit, which is otherwise quite similar structur-
ally to the other studied compounds.
Figure 4. The ORTEP20 drawing of complex [WCl2(eg)(buphe)2] (3e)
showing 30% probability ellipsoids. The hydrogen atoms have been
omitted for clarity. The crystals were grown from hexane.
The influence of the bulky phenolato ligands on the structure
of these compounds is evident in the orientation of the phenyl
groups with respect to the complex unit. In Table 2 a comparison
between the dihedral angles of the O4 coordination plane and
the planes of phenyl rings and also the dihedral angles between
two phenyl rings is presented. It can be seen that these values
vary greatly from compound to compound and between poly-
morphs.
different rotational positions, as shown by the dihedral angle
parameters in Table 2
The crystals of compounds 3a and 3c were obtained from
both acetonitrile (3a′ and 3c′) and from hexane (3a′′ and 3c′′)
solutions. In each case, the structure of the crystals was
dependent on the solvent. Compound 3a crystallized out from
both solvents as triclinic crystals with similar unit cell size, but
there were some differences between the actual structures (see
Table 2). Compound 3c formed monoclinic crystals from
acetonitrile and tetragonal ones from hexane. The crystals 3c′′
are enantiomeric, and tubular cavities run through the entire
In the high-valent metal alkoxides and aryloxides the M-O
distances are generally shorter than the values expected solely
on the basis of σ bonding. This indicates that π bonding (electron
donation from the p orbital of oxygen to the d orbitals of
tungsten) is present. As a result, the relationship between the
M-O bond distances and the degree of π bonding for the

Reactions of Bisdiolatotungsten(VI) Phenoxides
Inorganic Chemistry, Vol. 40, No. 23, 2001 6051
Conclusion
terminal alkoxides and phenoxides has been widely dis-
cussed.11,18 The value of the M-O-C angle can also, in theory,
reflect the degree of π donation to the metal, but it has been
shown to be an extremely flexible parameter and primarily
controlled by steric properties.18,19 In the newly prepared
compounds, the W-O-C(phenyl) angles vary from 146.6(8)°
(relevant W-O bond length 1.857(8) Å) to 172.3(6)°
(1.845(5) Å). However, in 3a′ the W-O-C(phenyl) angle is
166.0(4)° and the W-O distance 1.840(4) Å. This indicates that
the W-O distance is not responsive to the variation in the
W-O-C(phenyl) angle, although some correlation is discern-
ible. The crystal packing forces seem to have strong effects on
the bending of these bonds.
In conclusion, we have found that coordinated phenoxide
i
groups in [W(eg)2(OC6H3R2-2,6)2] (R ) Me, Pr) react with
elemental bromine, resulting in para-bromination of the phen-
yl ring. The halide-for-alkoxide substitution of bisdiolatotung-
sten(VI) phenoxides [W(eg)2(OAr)2] was accomplished using
HCl as the chloride source. This reaction leads to the displace-
ment of one ethanediolato ligand and the formation of the
dichloro complexes trans-[WCl2(eg)(OAr)2]. X-ray crystal
structure determinations confirmed the general structural fea-
tures of the complexes and trans orientation of the chloro
ligands.
Supporting Information Available: Crystallographic information
available as CIF. This material is available free of charge via the Internet
at http://pubs.acs.org.
(18) Steffey, B. D.; Fanwick, P. E.; Rothwell, I. P. Polyhedron 1990, 9,
963-968.
(19) Kanehisa, N.; Kai, Y.; Kasai, Y.; Yasuda, H.; Nakayama, Y.;
Nakamura, A. Bull. Chem. Soc. Jpn. 1992, 65, 1197-1201.
(20) Farrugia, L. J. J. App. Cryst. 1997, 30, 565.
IC010583T