Rhenium(VII) oxo-alkyl complexes: Reductive and α-elimination reactions

Article abstract of DOI:10.1021/om950761o

Alkylation of ReO₂(CH₂CMe₃)2X(py) (X = Cl, Br) with ZnR₂ at low temperature gives ReO₂(CH₂CMe₃)₂R (R = Me, CH₂CMe₃, CH₂SiMe₃, Ph) in high yield. The crystal structure Of ReO₂(CH₂CMe₃)₂Ph shows that it has a distorted trigonal bipyramidal structure with the oxo and Ph ligands in the equatorial plane. Photolysis Of ReO₂(CH₂CMe₃)S in pyridine gives neopentane and ReO₂(CHCMe₃)(CH₂CMe₃), and ReO₂(CHCMe₃)(CH₂CMe₃) reacts with quinuclidine to give ReO₂(CHCMe₃)(CH₂CMe₃)(quinuclidine). In the solid state, ReO₂-(CHCMe₃)(CH₂CMe₃) has a distorted tetrahedral structure, and ReO₂(CHCMe₃)(CH₂CMe₃)-(quinuclidine) is trigonal bipyramidal with the neopentylidene and oxo ligands defining the equatorial plane. The Re-N bond distance is long, suggesting the rhenium-quinuclidine interaction is weak. Thermolysis of ReO₂(CH₂CMe₃)₂Ph in pyridine gives ReO₂(CH₂CMe₃)-(py)₃ and neopentylbenzene. An X-ray structure of ReO₂(CH₂CMe₃)(py)₃ shows that it is octahedral with trans oxo groups. In solution ReO₂(CH₂CMe₃)(Py)₃ is unstable in the absence of excess pyridine, and in the solid state it readily loses pyridine. ReO₂(CH₂CMe₃)(Py)₃ reacts with MeC≡CMe and PhC≡CH to form ReO₂(CH₂CMe₃)(alkyne) compounds.

Full text of DOI:10.1021/om950761o

Organometallics 1996, 15, 1023-1032
1023
Rh en iu m (VII) Oxo-Alk yl Com p lexes: Red u ctive a n d
r-Elim in a tion Rea ction s
Shiang Cai,1a David M. Hoffman,*,1b and Derk A. Wierda1a,c
Departments of Chemistry, University of Houston, Houston, Texas 77204, and
Harvard University, Cambridge, Massachusetts 02138.
Received September 25, 1995X
Alkylation of ReO2(CH2CMe3)2X(py) (X ) Cl, Br) with ZnR2 at low temperature gives
ReO2(CH2CMe3)2R (R ) Me, CH2CMe3, CH2SiMe3, Ph) in high yield. The crystal structure
of ReO2(CH2CMe3)2Ph shows that it has a distorted trigonal bipyramidal structure with the
oxo and Ph ligands in the equatorial plane. Photolysis of ReO2(CH2CMe3)3 in pyridine gives
neopentane and ReO2(CHCMe3)(CH2CMe3), and ReO2(CHCMe3)(CH2CMe3) reacts with
quinuclidine to give ReO2(CHCMe3)(CH2CMe3)(quinuclidine). In the solid state, ReO2-
(CHCMe3)(CH2CMe3) has a distorted tetrahedral structure, and ReO2(CHCMe3)(CH2CMe3)-
(quinuclidine) is trigonal bipyramidal with the neopentylidene and oxo ligands defining the
equatorial plane. The Re-N bond distance is long, suggesting the rhenium-quinuclidine
interaction is weak. Thermolysis of ReO2(CH2CMe3)2Ph in pyridine gives ReO2(CH2CMe3)-
(py)3 and neopentylbenzene. An X-ray structure of ReO2(CH2CMe3)(py)3 shows that it is
octahedral with trans oxo groups. In solution ReO2(CH2CMe3)(py)3 is unstable in the absence
of excess pyridine, and in the solid state it readily loses pyridine. ReO2(CH2CMe3)(py)3 reacts
with MeCtCMe and PhCtCH to form ReO2(CH2CMe3)(alkyne) compounds.
There has recently been a renewed interest in the
chemistry of high oxidation state rhenium compounds.2
Herrmann and co-workers, for example, have compre-
hensively developed the chemistry of Cp*ReO3 and
MeReO3, including the latter’s use in catalytic olefin
metathesis,3 aldehyde alkenation,4 and olefin epoxida-
tion reactions,5 while Schrock and co-workers have
advanced the chemistry of rhenium imido, alkylidene,
and alkylidyne compounds culminating in the synthesis
of well-characterized Re(VII) olefin and acetylene meta-
thesis catalysts.6 Despite the interest in and the proven
importance of Re(VII) organometallic complexes in
catalytic processes, however, there are still relatively
few7-10 Re(VII) organometallic oxo complexes other than
Cp*ReO3, MeReO3, and their derivatives.2
We recently reported that photolysis of ReO2(CH2-
CMe3)3 gives ReO2(CHCMe3)(CH2CMe3), a rare example
of a Re oxo alkylidene complex.8d Motivated by this
result, we were interested in preparing Re(VII) com-
pounds analogous to ReO2(CH2CMe3)3 and examining
their thermal and photolytic decomposition. We report
here the synthesis of alkyl compounds of the type
ReO2(CH2CMe3)2R, full details concerning the synthesis
of ReO2(CHCMe3)(CH2CMe3) and its quinuclidine ad-
duct, and the thermolysis of ReO2(CH2CMe3)2Ph to give
reactive ReO2(CH2CMe3)(py)3.
Resu lts
Scheme 1 shows a brief summary of our synthetic
results.
ReO2(CH2CMe3)2R. ReO2(CH2CMe3)2X(py) (X ) Br,
Cl),8b prepared from [Re(µ-O)O(CH2CMe3)2]2,11 reacts
X Abstract published in Advance ACS Abstracts, J anuary 1, 1996.
(1) (a) Harvard University. Present address: Strem Chemicals, Inc.,
Newburyport, MA. (b) University of Houston. (c) Harvard University.
Present address: Department of Chemistry, St. Anselm College,
Manchester, NH.
(2) Hoffman, D. M. In Comprehensive Organometallic Chemistry II;
Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon Press: New
York, 1995; Vol. 6, Chapter 10.
(3) Herrmann, W. A.; Kuchler, J . G.; Felixberger, J . K.; Herdtweck,
E.; Wagner, W. Angew. Chem., Int. Ed. Engl. 1988, 27, 394; Angew.
Chem. 1988, 100, 420. Herrmann, W. A.; Wagner, W.; Flessner, U.
N.; Volkhardt, U.; Kombar, H. Angew. Chem., Int. Ed. Engl. 1991, 30,
1636; Angew. Chem. 1991, 103, 1704.
(7) Mertis, K.; Wilkinson, G. J . Chem. Soc., Dalton Trans. 1976,
1488. Gutierrez, A.; Wilkinson, G.; Hussain-Bates, B.; Hursthouse, M.
B. Polyhedron 1990, 9, 2081.
(8) (a) Cai, S.; Hoffman, D. M.; Lappas, D.; Woo, H.-G; Huffman, J .
C. Organometallics 1987, 6, 2273. (b) Cai, S.; Hoffman, D. M.; Wierda,
D. A. Organometallics 1988, 7, 2069. (c) Cai, S.; Hoffman, D. M.;
Wierda, D. A. J . Chem. Soc., Chem. Commun. 1988, 313. (d) Cai, S.;
Hoffman, D. M.; Wierda, D. A. J . Chem. Soc., Chem. Commun. 1988,
1489. (e) Cai, S.; Hoffman, D. M.; Wierda, D. A. Inorg. Chem. 1989,
28, 3784.
(4) Herrmann, W. A.; Wang, M. Angew. Chem., Int. Ed. Engl. 1991,
30, 1641; Angew. Chem. 1991, 103, 1709.
(5) Herrmann, W. A.; Marz, D.; Wagner, W.; Kuchler, J .; Weichsel-
baumer, G.; Fischer, R. (Hoechst AG) Ger. Offen. DE 3,902,357, 1990;
Chem. Abstr. 1991, 114, 143714u. Herrmann, W. A.; Fischer, R. W.;
Marz, D. W. Angew. Chem., Int. Ed. Engl. 1991, 30, 1638; Angew.
Chem. 1991, 103, 1706. Herrmann, W. A.; Fischer, R. W.; Scherer, W.;
Rauch, M. U. Angew. Chem., Int. Ed. Engl. 1993, 32, 1157; Angew.
Chem. 1993, 105, 1209.
(6) (a) Toreki, R.; Schrock, R. R. J . Am. Chem. Soc. 1990, 112, 2448.
(b) Toreki, R.; Vaughan, G. A.; Schrock, R. R.; Davis, W. M. J . Am.
Chem. Soc. 1993, 115, 127. (c) Schrock, R. R.; Weinstock, I. A.; Horton,
A. D.; Liu, A. H.; Schofield, M. H. J . Am. Chem. Soc. 1988, 110, 2686.
(d) Weinstock, I. A.; Schrock, R. R.; Davis, W. M. J . Am. Chem. Soc.
1991, 113, 135.
(9) (a) Takacs, J .; Kiprof, P.; Riede, J .; Herrmann, W. A. Organo-
metallics 1990, 9, 782. (b) Takacs, J .; Cook, M. R.; Kiprof, P.; Kuchler,
J . G.; Herrmann, W. A. Organometallics 1991, 10, 316. (c) Herrmann,
W. A.; Watzlowik, P.; Kiprof, P. Chem. Ber. 1991, 124, 1101. (d)
Herrmann, W. A.; Watzlowik, P. J . Organomet. Chem. 1992, 441, 265.
(e) Herrmann, W. A.; Weichselbaumer, G.; Paciello, R. A.; Fischer, R.
A.; Herdtweck, E.; Okuda, J .; Marz, D. W. Organometallics 1990, 9,
489. (f) Takacs, J .; Kiprof, P.; Kuchler, J . G.; Herrmann, W. A. J .
Organomet. Chem. 1989, 369, C1.
(10) Horton, A. D.; Schrock, R. R. Polyhedron 1988, 7, 1841. Horton,
A. D.; Schrock, R. R.; Freudenberger, J . H. Organometallics 1987, 6,
893. Toreki, R.; Schrock, R. R.; Davis, W. M. J . Am. Chem. Soc. 1992,
114, 3367.
0276-7333/96/2315-1023$12.00/0 © 1996 American Chemical Society

1024 Organometallics, Vol. 15, No. 3, 1996
Cai et al.
Sch em e 1
F igu r e 1. Plot of ReO2(CH2CMe3)2Ph showing the atom-
numbering scheme (30% probability level ellipsoids).
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for ReO2(CH2CMe3)2P h
Distances
Re-O(1)
Re-C(1)
Re-C(3)
1.709(6)
2.163(8)
2.142(6)
Re-O(2)
Re-C(2)
1.704(5)
2.152(7)
Angles
O(1)-Re-O(2)
O(1)-Re-C(1)
O(2)-Re-C(1)
O(1)-Re-C(2)
O(2)-Re-C(2)
O(1)-Re-C(3)
O(2)-Re-C(3)
123.8(2)
98.6(3)
97.3(3)
99.9(3)
96.3(2)
117.0(2)
119.2(3)
C(1)-Re-C(2)
C(1)-Re-C(3)
C(2)-Re-C(3)
Re-C(1)-C(10)
Re-C(2)-C(20)
Re-C(3)-C(4)
Re-C(3)-C(8)
145.4(2)
72.5(2)
73.1(2)
114.0(5)
114.4(4)
119.2(5)
122.3(4)
with dialkylzinc reagents at low temperature to give
ReO2(CH2CMe3)2R compounds in high yield (eq 1). For
The O(2)-Re-O(1) angle (123.8(2)°) in ReO2(CH2-
CMe3)2Ph is larger than the O-Re-O angles in octa-
hedral ReO2(CH2CMe3)2Br(py) (107.4(3)°)8b and the
5-coordinate compounds ReO2(CH2CMe3)3 (117.4(5)°),
[ReO2(CH2CMe3)2]2(µ-O) (107.5(6)° (av)), and ReO2(CH2-
CMe3)2(SPh) (117.7(3)°).8c,e The Re-O and Re-C dis-
tances in ReO2(CH2CMe3)2Ph are normal, and the
neopentyl and phenyl Re-C distances are within 3σ of
each other.
IR spectra for the ReO2(CH2CMe3)2R compounds show
two bands in the region 940-1000 cm-1 (e.g., R ) Ph,
987 and 945 cm-1) that are characteristic of the sym-
metric and antisymmetric stretches arising from a cis-
ReO2 fragment.12
the phenyl and trimethylsilylmethyl derivatives, work-
up of the reaction mixtures included treatment with
oxygen-free water to destroy unreacted dialkylzinc
reagents and ZnRX. Final isolation of the compounds
as orange solids was accomplished by vacuum sublima-
tion. The compounds are very soluble in hydrocarbon
solvents. They are stable to oxygen-free water but are
light and thermally sensitive. The preparation of
ReO2(CH2CMe3)3 from ReO2(CH2CMe3)2X(py) and
Zn(CH2CMe3)2 (eq 1) is a more convenient synthesis
than the previously reported one.8c
The structure of ReO2(CH2CMe3)2Ph was determined
by X-ray crystallography. A thermal ellipsoid plot is
presented in Figure 1, and selected bond distances and
angles are given in Table 1. The ReO2C3 core can be
described as distorted trigonal bipyramidal with the
plane defined by Re, O(1), O(2), and C(3) of the phenyl
ring taken as the equatorial plane. The axial neopentyl
methylene carbons, C(1) and C(2), bend in the direction
of the phenyl ligand giving an angle of 145.4(2)° for
C(1)-Re-C(2). The bending of cis ligands away from
the oxo groups is a common feature for d0 cis-dioxo
compounds.
Consistent with the solid-state structure of ReO2(CH2-
1
CMe3)2Ph, room-temperature H NMR spectra for the
ReO2(CH2CMe3)2R compounds show only a singlet for
the neopentyl methylene protons, indicating that the
neopentyl ligands occupy axial sites. Variable-temper-
ature NMR spectra recorded for ReO2(CH2CMe3)2Ph
(+23 to -90 °C) are consistent with the solid-state
structure being retained in solution over the entire
temperature range. Spectra recorded for ReO2(CH2-
CMe3)2Me in the same temperature range are also
invariant.
In contrast, 1H NMR spectra recorded for ReO2(CH2-
CMe3)2(CH2SiMe3) display a temperature dependence.
As the sample is cooled, the resonance arising from the
axial methylene protons (CH2CMe3) broadens, then
collapses into the baseline (at -65 °C), and finally
reappears as an AB quartet (-86 °C). The singlet
(11) Cai, S.; Hoffman, D. M.; Huffman, J . C.; Wierda, D. A.; Woo,
H.-G. Inorg. Chem. 1987, 26, 3693. Huggins, J . M.; Whitt, D. R.;
Lebioda, L. J . Organomet. Chem. 1986, 312, C15.
(12) Nakamoto, K. Infrared and Raman Spectra of Inorganic and
Coordination Compounds, 4th ed.; J ohn Wiley & Sons: New York,
1986.

Rhenium(VII) Oxo-Alkyl Complexes
Organometallics, Vol. 15, No. 3, 1996 1025
arising from the equatorial methylene protons (CH2-
SiMe3) broadens slightly as the sample is gradually
cooled, but it never disappears into the baseline. The
1
low-temperature-limiting H NMR spectrum of ReO2-
(CH2CMe3)2(CH2SiMe3) closely resembles the limiting
spectra of ReO2(CH2SiMe3)3 and ReO2(CH2CMe3)3,8c the
latter having a highly distorted tbp structure in the solid
state in which the methylene groups lean toward one
of the oxo ligands. Thus, the NMR data suggest that
ReO2(CH2CMe3)2(CH2SiMe3) also has a distorted geom-
etry in the low-temperature limit. The temperature-
independent spectra observed for ReO2(CH2CMe3)2Me
could mean it adopts the undistorted ReO2(CH2CMe3)2-
Ph structure or that we simply could not freeze out the
pathway that generates virtual C2v symmetry in the
molecule. The lesser steric crowding in ReO2(CH2-
CMe3)2Me compared to the other alkyl derivatives could
be the basis for either explanation.
F igu r e 2. Plot of ReO2(CHCMe3)(CH2CMe3) showing the
atom-numbering scheme (30% probability level ellipsoids).
ReO2(CHCMe3)(CH 2CMe3) a n d ReO2(CHCMe3)-
(CH2CMe3)(qu in ). Photolysis of ReO2(CH2CMe3)3 in
pyridine for 1 h using Pyrex-filtered light from a
medium-pressure
mercury lamp
gives
ReO2-
(CHCMe3)(CH2CMe3) and neopentane as the only iden-
tifiable products (eq 2). Acetonitrile can also be used
as a solvent for the photolysis reaction, but photolysis
in hydrocarbon solvents gives a mixture of ReO2-
(CHCMe3)(CH2CMe3) and Re(VI) [Re(µ-O)O(CH2-
CMe3)2]2.11 A possible explanation for the solvent
dependence is that coordinating solvents weakly associ-
ate with ReO2(CH2CMe3)3, thereby increasing steric
congestion and facilitating R-hydrogen elimination.
ReO2(CHCMe3)(CH2CMe3) does not react under mild
conditions with cyclic or acyclic olefins or alkynes. Since
coordination of olefin or alkyne is a likely prerequisite
for reactivity with ReO2(CHCMe3)(CH2CMe3), we re-
acted the alkylidene complex with quinuclidine to
determine if an adduct could be formed with a strong
donor ligand. Thus, the addition of quinuclidine to the
crude reaction mixture from (2) gave yellow ReO2-
(CHCMe3)(CH2CMe3)(quin) (quin ) quinuclidine), which
was isolated in 54% yield based on ReO2(CH2CMe3)3
after crystallization from acetonitrile.
F igu r e 3. Plot of ReO2(CHCMe3)(CH2CMe3)(quin) showing
the atom-numbering scheme (30% probability level el-
lipsoids).
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for ReO2(CHCMe3)(CH2CMe3)
Distances
Re-O(2)
1.696(7)
1.706(7)
1.501(13)
Re-C(2)
2.114(9)
1.869(9)
1.558(13)
Re-O(1)
Re-C(1)
C(1)-C(10)
C(2)-C(20)
Angles
O(2)-Re-O(1)
O(2)-Re-C(2)
O(1)-Re-C(2)
O(2)-Re-C(1)
124.6(4)
105.0(4)
106.9(3)
111.7(4)
O(1)-Re-C(1)
C(2)-Re-C(1)
Re-C(2)-C(20)
Re-C(1)-C(10)
109.3(4)
94.8(4)
117.4(6)
136.6(8)
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for ReO2(CHCMe3)(CH2CMe3)(qu in )
ReO2(CHCMe3)(CH2CMe3) and ReO2(CHCMe3)(CH2-
CMe3)(quin) are very soluble in common solvents, and
both are moderately air-stable in the solid state and in
solution. ReO2(CHCMe3)(CH2CMe3) sublimes readily
under vacuum.
Distances
Re-O(1)
Re-O(2)
Re-C(1)
Re-C(2)
1.718(4)
1.722(4)
1.893(6)
2.144(7)
Re-N
C(1)-C(10)
C(2)-C(20)
2.425(5)
1.494(8)
1.540(9)
ReO2(CHCMe3)(CH2CMe3) (Figure 2) and ReO2-
(CHCMe3)(CH2CMe3)(quin) (Figure 3) were character-
ized by X-ray crystallography. Selected bond distances
and angles are given in Tables 2 and 3.
J udging by the 3σ criterion, there is no significant
difference in the RedC(1) or Re-O distances between
the two complexes. Also, the RedC distances (1.869(9)
and 1.893(6) Å) are close to those reported for Re-
(CCMe3)(CHCMe3)I2(py)2 (1.873(9) Å),13 [Re(CCMe3)-
(CHCMe3)(ArNH2)Cl2]2 (1.89(1) Å),6a and Re(CHCMe3)-
(N-2,6-C6H3-i-Pr2)(O-2,6-C6H3Cl2)3 (1.87(2) Å),14 and
Angles
O(1)-Re-O(2)
O(1)-Re-C(1)
O(2)-Re-C(1)
O(1)-Re-C(2)
O(2)-Re-C(2)
C(1)sResC(2)
133.3(2)
O(1)-Re-N
81.5(2)
82.3(2)
94.2(2)
172.0(2)
136.8(4)
120.5(4)
110.8(2)
113.9(2)
95.6(2)
94.5(2)
93.8(3)
O(2)-Re-N
C(1)-Re-N
C(2)-Re-N
Re-C(1)-C(10)
ResC(2)sC(20)
the Re-O distances (1.70-1.72 Å) are normal. The
RedCRsCâ angles in both complexes (≈137°) are about
14° smaller than the angle observed in Re(CCMe3)-
(CHCMe3)I2(py)2,13 but they are close to those observed
(13) Edwards, D. S.; Biondi, L. V.; Ziller, J . W.; Churchill, M. R.;
Schrock, R. R. Organometallics 1983, 2, 1505.
(14) Schofield, M. H.; Schrock, R. R.; Park, L. Y. Organometallics
1991, 10, 1844.

1026 Organometallics, Vol. 15, No. 3, 1996
Cai et al.
Ta ble 4. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for ReO2(CH2CMe3)(p y)3
in [Re(CCMe3)(CHCMe3)(ArNH2)Cl2]2 (140(1)°) and Re-
(CHCMe3)(N-2,6-C6H3-i-Pr2)(O-2,6-C6H3Cl2)3 (139(1)°).6a,14
Undistorted alkylidene ligands are usually found in
compounds in which there are strong π-donating ligands,
such as oxo and imido groups. The Re-N bond distance
(2.425(5) Å) in ReO2(CHCMe3)(CH2CMe3)(quin) is com-
parable to the Re-N distances in other complexes in
which the amine ligand is trans to an alkyl group, such
as ReO3(Me)(NH2Ph) (2.469(4) Å),15 ReO2(Me)(py)(1,2-
O2C6H4) (2.347(4) Å),9a and ReO3R(quin) (R ) Et, CH2-
Distances
Re-O(1)
Re-O(2)
Re-N(1)
Re-N(2)
1.748(9)
1.741(9)
2.348(11)
2.136(11)
Re-N(3)
Re-C(4A)
Re-C(4B)
2.158(11)
2.171(14)
2.187(19)
Angles
O(1)-Re-O(2)
O(1)-Re-N(1)
O(2)-Re-N(1)
O(1)-Re-N(2)
O(2)-Re-N(2)
O(1)-Re-C(4A)
O(2)-Re-C(4A)
N(1)-Re-C(4A)
N(2)-Re-C(4A)
N(3)-Re-C(4A)
Re-C(4A)-C(40)
165.9(5)
82.7(5)
83.3(4)
89.6(5)
90.3(5)
103.1(7)
90.8(7)
171.6(7)
81.5(5)
101.9(5)
129.9(11)
N(1)-Re-N(3)
N(2)-Re-N(3)
N(1)-Re-N(2)
O(1)-Re-N(3)
O(2)-Re-N(3)
O(1)-Re-C(4B)
O(2)-Re-C(4B)
N(1)-Re-C(4B)
N(2)-Re-C(4B)
N(3)-Re-C(4B)
Re-C(4B)-C(40)
84.1(4)
176.6(4)
92.4(4)
89.9(4)
89.4(4)
84.9(7)
109.1(7)
165.2(8)
95.4(9)
87.9(9)
127.2(15)
SiMe3, CH2CMe3, cyclopropyl; av Re-N ) 2.41 Å).16
A
normal Re-N distance is around 2.1-2.2 Å (see the next
section).
The ReO2C2 core of ReO2(CHCMe3)(CH2CMe3) has a
distorted tetrahedral geometry. The C(2)-Re-O(1) and
C(2)-Re-O(2) angles (106.9(3) and 105.0(4)°) are close
to the expected tetrahedral values, but the C(1)-Re-
C(2) angle is only 94.8 (4)° and O(1)-Re-O(2) is 124.6-
(4)°. The geometry about the rhenium in ReO2-
(CHCMe3)(CH2CMe3)(quin) is trigonal bipyramidal with
the oxo and neopentylidene ligands defining the trigonal
plane and the quinuclidine and neopentyl ligands oc-
cupying the axial positions. The axial ligands are
slightly bent away from the bulky neopentylidene
ligand. The rhenium, neopentylidene R carbon, and two
oxo ligands are nearly coplanar, but the O-Re-C(1)
angles are smaller (by 6 and 10°) than 120° as a
consequence of the large O-Re-O angle of 133°. The
O-Re-O angles in ReO2(CHCMe3)(CH2CMe3) (125°)
and its quinuclidine adduct (133°) are larger than those
found in the related complexes ReO3R (107-112°)17 and
ReO3R(amine) (115-120°).15,16
alkylidene product by 1H NMR. In contrast, photolysis
of ReO2(CH2CMe3)2Ph produces a mixture of products
that includes Re(V) ReO2(CH2CMe3)(py)3 and neopen-
tylbenzene (identified by 1H NMR). Subsequently, it
was found that thermolysis of ReO2(CH2CMe3)2Ph at 70
°C in pyridine gives ReO2(CH2CMe3)(py)3 more cleanly
than the photolysis route (eq 3).
ReO2(CH2CMe3)(py)3 crystallizes from saturated pyr-
idine solutions at low temperature. The crystals must
be dried in vacuo at low temperature for a short time
period, or under ambient conditions in a glovebox, to
keep the three pyridine ligands intact. Under dynamic
vacuum a for 12 h at room temperature a compound
with a stoichiometry close to ReO(CH2CMe3)(py)2 (de-
Spectroscopic data for ReO2(CHCMe3)(CH2CMe3) and
ReO2(CHCMe3)(CH2CMe3)(quin) are consistent with the
solid-state structures. In particular, the methylene
protons of the neopentyl alkyl ligand in each compound
1
appears as a sharp AB quartet in the H NMR spectra,
1
termined by H NMR) is obtained.
indicating that the neopentylidene plane is perpendicu-
lar to the Re-CH2CMe3 bond vector in solution and the
neopentylidene ligand does not rotate rapidly enough
to broaden the NMR signals. The IR spectrum for
ReO2(CHCMe3)(CH2CMe3) has strong bands at 986 and
947 cm-1 arising from the cis-ReO2 moiety.12 Similar
bands appear in the spectrum of the quinuclidine
adduct, but both are shifted to lower energy by ≈40-
50 cm-1. Assuming an 18-electron count for ReO2-
(CHCMe3)(CH2CMe3) and ReO2(CHCMe3)(CH2CMe3)-
(quin), the predicted Re-O bond orders are 3 for
ReO2(CHCMe3)(CH2CMe3) and 2 1/2 for the quin adduct,
consistent with the lower energy Re-O stretching bands
observed for the quinuclidine adduct. For comparison,
the Re-O stretching frequencies in ReO3R (Re-O bond
ReO2(CH2CMe3)(py)x (x < 3) decomposes within a few
minutes at room temperature in common organic sol-
vents unless there is excess pyridine present. The
decomposition products could not be identified. At-
tempts to prepare ReO2(CH2CMe3)(py)x from [ReO2-
(py)4]Cl and LiCH2CMe3 were unsuccessful.
ReO2(CH2CMe3)(py)3 was characterized by X-ray crys-
tallography. Selected bond distances and angles are
presented in Table 4. In the course of solving the
structure it was found that the neopentyl group is
disordered. The thermal ellipsoid plot in Figure 4 shows
one of the two resolved components of the disorder.
The coordination geometry about the rhenium is best
described as octahedral. The oxo ligands are trans but
they are slightly bent ( O-Re-O ) 165.9(5)°) in the
direction of N(1). Generally, d2 dioxo compounds have
a trans rather than a cis configuration. The Re-O
distances [average 1.745(9) Å] are similar to those in
[ReO2(py)4]+ and other Re(V) trans-dioxo compounds,18
all of which are best described as having Re-O double
bonds. The Re-C-C angles in the Re neopentyl group
appear to be ≈5-10° larger than normal (molecule A,
2
order 2 /3) and ReO3R(quin) (Re-O bond order 2 1/3)
are ≈955 and ≈920 cm-1, respectively.16,17
R eO2(CH 2CMe3)(p y)3. Photolysis of ReO2(CH2-
CMe3)2R, R ) Me or CH2SiMe3, under conditions similar
to those used to prepare ReO2(CHCMe3)(CH2CMe3),
gives ReO2(CHCMe3)(CH2CMe3) as the only identifiable
(15) Herrmann, W. A.; Weichselbaumer, G.; Herdtweck, E. J .
Organomet. Chem. 1989, 372, 371.
(16) Herrmann, W. A.; Roma˜o, C. C.; Fischer, R. W.; Kiprof, P.; de
Me´ric de Bellefon, C. Angew. Chem., Int. Ed. Engl. 1991, 30, 185;
Angew. Chem. 1991, 103, 183. Herrmann, W. A.; Ku¨hn, F. E.; Roma˜o,
C. C.; Huy, H. T.; Wang, M.; Fischer, R. W.; Kiprof, P.; Scherer, W.
Chem. Ber. 1993, 126, 45.
(17) de Me´ric de Bellefon, C.; Herrmann, W. A.; Kiprof, P.; Whitaker,
C. R. Organometallics 1992, 11, 1072.
(18) (a) J ohnson, J . W.; Brody, J . F.; Ansell, G. B.; Zentz, S. Inorg.
Chem. 1984, 23, 2415. (b) Calvo, C.; Krishnamachari, N.; Lock, C. J .
L. J . Cryst. Mol. Struct. 1971, 1, 161. Lock, C. J . L.; Turner, G. Acta
Crystallogr. 1978, B34, 923. (c) Edwards, P. G.; Skapski, A. C.; Slawin,
A. M. Z.; Wilkinson, G. Polyhedron 1984, 3, 1083. (d) Beard, J . H.;
Casey, J .; Murmann, R. K. Inorg. Chem. 1965, 4, 797. (e) Murmann,
R. K.; Schlemper, E. O. Inorg. Chem. 1971, 10, 2352.

Rhenium(VII) Oxo-Alkyl Complexes
Organometallics, Vol. 15, No. 3, 1996 1027
IR spectra for the alkyne adducts show two strong
bands (e.g., 966 and 921 cm-1 for the 2-butyne adduct)
assigned to the symmetric and antisymmetric stretches
of cis-dioxo groups. These are similar to those reported
for ReO2(Me)(alkyne) (alkyne ) 2-butyne and phenyl-
acetylene).19 The IR spectra also show weak-medium
intensity bands at 1836 cm-1 for ReO2(CH2CMe3)-
(MeCtCMe) and 1738 cm-1 for ReO2(CH2CMe3)-
(PhCtCH) that are assigned to the alkyne carbon-
carbon bond stretches. These values are ≈400 cm-1
lower than for the free alkynes20 suggesting strong back-
bonding and concomitant C-C bond order reduction.
The 1H NMR spectrum for ReO2(CH2CMe3)-
(MeCtCMe) has two singlets in a 2:9 ratio assigned to
the methylene and methyl protons of the neopentyl
ligand and two quartets (5J HH ) 1.03 Hz) in a 1:1 ratio
assigned to the methyl protons of the 2-butyne ligand.
This suggests that the Re-CH2 and CtC vectors lie in
a mirror plane that bisects the O-Re-O angle. 13C-
{1H} NMR spectra for the adducts have resonances in
the region 125-140 ppm assigned to the acetylenic
carbons of the alkyne ligands.
F igu r e 4. Plot of ReO2(CH2CMe3)(py)3 showing the atom-
numbering scheme (30% probability level ellipsoids).
127°; molecule B, 130°), but this is probably an artifact
of the disorder in the neopentyl ligand.
The Re-N distances to the mutually trans py ligands
(N(2) and N(3), average 2.147(11) Å) are normal; for
example, they are close to those observed in [ReO2-
(py)4]+, [ReO2(en)2]+, and [ReO2(4-py-Me)4]+.18a,e The
Re-N distance to the py trans to the neopentyl group
(2.348(11) Å), however, is about 0.2 Å longer than the
average of the other two Re-N distances due to the
strong trans influence of the alkyl ligand.
On the basis of the spectroscopic data, the adducts
are proposed to have tetrahedral-like structures, II. The
proposed structure is the same as found for structurally
characterized ReO2(Me)(PhCtCPh).19
Consistent with the solid-state structure, the 1H NMR
spectrum for ReO2(CH2CMe3)(py)3 in CD2Cl2 at -70 °C
reveals two singlets in the integral ratio of 2:9 assigned
to the methylene and methyl protons of the neopentyl
ligand and two sets of three multiplets further downfield
which are assigned to the ortho-, meta-, and para-
protons of the two different types of pyridine ligands.
As the solution is warmed, the two sets of multiplet
resonances merge together into one set, indicating
pyridine ligand exchange. The sample begins to de-
compose at -10 °C, producing unidentified products.
When a CD2Cl2/pyridine-d5 (≈100 equiv) mixture is
added to ReO2(CH2CMe3)(py)3, the compound is stabi-
NOE NMR experiments were used to distinguish the
two isomers of ReO2(CH2CMe3)(PhCtCH). The results
clearly show that the neopentyl-ligand methylene pro-
tons are closer to the acetylene proton in the major
isomer than in the minor isomer; thus, the major isomer
is the one in which the Ph group is farther away from
the neopentyl ligand (i.e., R′′ ) Ph in II). This isomer
is favored because it is the less sterically crowded than
the other.
1
lized by the excess pyridine and a room-temperature H
NMR spectrum can be recorded. Under these condi-
tions, the pyridine-d5 exchanged with all of the pyridine
ligands according to the NMR spectrum.
IR spectra recorded for Nujol mulls of ReO2(CH2-
CMe3)(py)x, x ≈ 2 or 3, are nearly identical. Both show
a strong band at 803 cm-1 that can be assigned to the
antisymmetric stretch of the trans-dioxo group.12 The
IR spectra also show bands near 1600 cm-1, which are
assigned to the pyridine ligands. The similarity of the
IR spectra suggests that ReO2(CH2CMe3)(py)2 has a
structure akin to ReO2(CH2CMe3)(py)3. A possible
structure is I.
Discu ssion
We have presented the synthesis of three new 5-co-
ordinate Re(VII) dioxo compounds of the type ReO2(CH2-
CMe3)2R and an improved synthesis of ReO2(CH2-
CMe3)3. Prior to this work, the only reported compounds
of this kind were ReO2R3, R ) Me,7 CH2CMe3,8c and
CH2SiMe3,8a and related compounds such as ReO2(CH2-
CMe3)2X, X ) halide, alkoxide, and thiolate,8b,e and
ReO2MeX2, X2 ) chelating dialkoxide.9a-c
It is interesting that the low-temperature-limiting 1H
NMR spectrum of ReO2(CH2CMe3)2(CH2SiMe3) is con-
ReO2(CH2CMe3)(a lk yn e). ReO(CH2CMe3)(py)x re-
acts with 2-butyne in toluene/pyridine and with neat
PhCtCH to give alkyne adducts (eq 4). Isolation of the
adducts is accomplished by vacuum sublimation. The
isolated phenylacetylene complex is a 5:1 mixture of two
isomers.
(19) Felixberger, J . K.; Kuchler, J . G.; Herdtweck, E.; Paciello, R.
A.; Herrmann, W. A. Angew. Chem., Int. Ed. Engl. 1988, 27, 946.
Herrmann, W. A.; Felixberger, J . K.; Kuchler, J . G.; Herdtweck, E. Z.
Naturforsch. B 1990, 45, 876.
(20) Dollish, F. R.; Fateley, W. G.; Bentley, F. F. Characteristic
Raman Frequencies of Organic Compounds; J ohn Wiley & Sons: New
York, 1974; pp 153-155.

1028 Organometallics, Vol. 15, No. 3, 1996
Cai et al.
sistent with it having the same distorted structure as
ReO2R3 (R ) CH2CMe3, CH2SiMe3).8c ReO2(CH2CMe3)3
has a highly distorted tbp structure in the solid state
in which the axial methylene groups lean toward one
of the oxo ligands. The driving force for the distorted
geometry in ReO2(CH2CMe3)3 was postulated to be an
interaction between one of the oxo ligands and the axial
methylene protons. Steric factors were specifically
excluded as being the cause of the distortion. In
contrast, we have found that ReO2(CH2CMe3)2Ph does
not have a distorted geometry in the solid state, nor does
it appear to adopt a distorted geometry in solution. If
the hypothesis concerning oxo-methylene interactions
in ReO2R3 (R ) CH2CMe3, CH2SiMe3) is correct, then
it is unclear why ReO2(CH2CMe3)2Ph does not show
similar interactions and structural distortions. On this
basis, it is possible that the distorted stuctures of
ReO2R′2R (R′ ) CH2CMe3, R ) CH2CMe3 or CH2SiMe3;
R′ ) R ) CH2SiMe3) are in fact due to steric factors
and the original hypothesis concerning oxo-methylene
interactions is incorrect.21
Our results show that photolysis of ReO2(CH2CMe3)3
in pyridine or acetonitrile gives ReO2(CHCMe3)(CH2-
CMe3) and neopentane by R-elimination, but photolysis
or thermolysis of ReO2(CH2CMe3)2Ph in pyridine gives
Re(V) ReO2(CH2CMe3)(py)3 and neopentylbenzene by
(formal) reductive elimination. Although it is somewhat
surprising the reduction occurs given the marked pro-
pensity of rhenium to form Re-C multiple bonds, we
have previously reported that photolysis of ReO2(CH2-
SiMe3)3 also induces reduction, giving Re(VI) [Re(µ-
O)O(CH2SiMe3)2]2.8a The instability of ReO2(CH2CMe3)-
(py)3 in the absence of excess pyridine, conditions which
favor formation of ReO2(CH2CMe3)(py)x where x < 3, is
also surprising, and the reason for the instability is not
clear.
The formation of ReO2(CHCMe3)(CH2CMe3)(quin)
from ReO2(CHCMe3)(CH2CMe3) indicates that the latter
is electrophilic and sterically open enough to bind a
potent donor ligand. The Re-N distance is long and
presumably weak, however, due to the strong trans
influence of the neopentyl ligand. This may explain why
ReO2(CHCMe3)(CH2CMe3) does not react with weak
donors such as alkynes or olefins. If 4-coordinate
derivatives with ligands that have less trans influence
than an alkyl could be prepared, such as ReO2-
(CHCMe3)X (X ) halide, alkoxide), they may bind
alkynes or olefins thereby leading to RedC bond reac-
tivity.
The alkylidene and Re(V) chemistry we have de-
scribed is closely related to Schrock and co-workers’
imido chemistry. They showed, for example, that Re-
(NCMe3)2(CHSiMe3)(CH2SiMe3)3 is cleanly formed upon
photolysis of Re(NCMe3)2(CH2SiMe3)3, while the related
imido-neopentylidene derivative apparently forms spon-
taneously via a Re(NCMe3)2(CH2CMe3)3 intermediate.
Schrock and co-workers have also synthesized Re(N-2,6-
i-Pr2C6H3)2(CH2CMe3)(py)2, an imido analog of ReO2(CH2-
CMe3)(py)3, by reducing Re(N-2,6-i-Pr2C6H3)2(CH2CMe3)-
Cl2 or alkylating Re(N-2,6-i-Pr2C6H3)2Cl(py)2.22 Re(N-
2,6-i-Pr2C6H3)2(CH2CMe3)(py)2 reacts with π acceptors
and phosphine to form Re(N-2,6-i-Pr2C6H3)2(CH2CMe3)L
(L ) PMe2Ph, η2-2-butyne, η2-Me2CdO, η2-t-Bu(H)CdO,
η2-norbornene), compounds that are analogous to
ReO2(CH2CMe3)(alkyne). Also pertinent is Herrmann
and co-workers’ phosphine reduction of MeReO3 to
produce the putative Re(V) intermediate, ReO2Me-
(OPR3), which is subsequently trapped by alkyne to give
ReO2Me(alkyne).19
Finally, we mention in passing the large O-Re-O
angles observed in ReO2(CH2CMe3)2Ph (123.8(2)°),
ReO2(CHCMe3)(CH2CMe3) (124.6(4)°), and ReO2-
(CHCMe3)(CH2CMe3)(quin) (133.3(2)°). Previously, we
structurally characterized ReO2(CH2CMe3)2Br(py),
ReO2(CH2CMe3)3, [ReO2(CH2CMe3)2]2(µ-O), and ReO2-
(CH2CMe3)2(SPh) having O-Re-O angles of 107.4(3),8b
117.4(5),8c 107.5(6)° (av),8e and 117.7(3)°,8e respectively.
Typically, d0 4-, 5-, and 6-coordinate transition-metal
dioxo complexes have O-M-O angles in a narrow
range of 105-115°, although most of the structural data
comes from group 5 and 6 complexes. The wide range
of angles observed for the rhenium compounds suggests
they have a shallower energy potential for O-M-O
variation than do the early transition metal complexes,
but a firm conclusion or a rationalization for why this
may be the case should be deferred until more rhenium-
(VII) dioxo complexes are structurally characterized.
Con clu sion
ZnR2 alkylation of ReO2(CH2CMe3)2X(py) at low tem-
perature gives ReO2(CH2CMe3)2R (R ) Me, CH2CMe3,
CH2SiMe3, Ph) in high yield. The crystal structure of
ReO2(CH2CMe3)2Ph shows that it has a distorted trigo-
nal bipyramidal structure with the oxo and Ph ligands
in the equatorial plane. Photolysis of ReO2(CH2CMe3)3
in pyridine gives neopentane and ReO2(CHCMe3)(CH2-
CMe3). ReO2(CHCMe3)(CH2CMe3) reacts with quinu-
clidine to give ReO2(CHCMe3)(CH2CMe3)(quin), but it
does not react with olefins. In the solid state, ReO2-
(CHCMe3)(CH2CMe3) has a distorted tetrahedral struc-
ture, and ReO2(CHCMe3)(CH2CMe3)(quinuclidine) is
trigonal bipyramidal with the neopentylidene and oxo
ligands defining the equatorial plane. The long Re-N
distance suggests a weak quinuclidine interaction.
Thermolysis of ReO2(CH2CMe3)2Ph in pyridine gives
ReO2(CH2CMe3)(py)3 and neopentylbenzene. An X-ray
structure of ReO2(CH2CMe3)(py)3 shows that it has an
octahedral structure with trans oxo groups. ReO2(CH2-
CMe3)(py)3 readily loses pyridine and reacts with alkynes
to form ReO2(CH2CMe3)(alkyne).
Exp er im en ta l Section
All manipulations and reactions were carried out under an
atmosphere of dry, oxygen-free nitrogen or argon by using
standard Schlenk techniques or dryboxes. Solvents were
purified by standard techniques. Proton and 13C NMR spectra
were referenced internally to solvent 1H and 13C resonances,
respectively. Infrared spectra were referenced externally to
the 1601 cm-1 band of polystyrene. ReO2(CH2CMe3)2X(py) (X
) Cl, Br) was prepared from [Re(µ-O)O(CH2CMe3)2]2 as
described previously.8b ZnR2 (R ) Me, CH2SiMe3, CH2CMe3)
compounds were prepared as described in the literature.23
(21) If this is the case, then the long Re-O distance observed8c in
ReO2(CH2CMe3)3 is probably due to a crystallography error, although
we have subsequently not been able to identify any obvious problem
with the data or structure refinement.
(22) Williams, D. S.; Schofield, M. H. Schrock, R. R. Organometallics
1993, 12, 4560. Weinstock, I. A.; Schrock, R. R.; Williams, D. S.; Crowe,
W. E. Organometallics 1991, 10, 1.

Rhenium(VII) Oxo-Alkyl Complexes
Organometallics, Vol. 15, No. 3, 1996 1029
Zn P h 2. In a three-neck round bottom flask equipped with
a condenser and a liquid-dropping funnel was placed dry ZnCl2
(7.00 g, 51.4 mmol) and diethyl ether (250 mL). To the mixture
was slowly added a light brown solution of Mg(Ph)Br in diethyl
ether (3.1 M, 105 mmol) via the dropping funnel. The mixture
was stirred at room temperature for 12 h and then refluxed
for 3 h after the addition was completed. The mixture was
cooled to room temperature and filtered, and the solids that
were collected on the frit were discarded. The volatile
components were removed under vacuum from the light brown
filtrate, and the residue was extracted with toluene (1 × 200
mL, 1 × 20 mL). The extracts were combined, and the volume
was reduced under vacuum to ≈100 mL. Cooling the solution
to -50 °C produced colorless crystals which were isolated by
removing the mother liquor via a cannula. The crystals were
dried under vacuum (yield 6.07 g, 54%). 1H NMR (CD3CN):
δ 7.62 (m, 2, Ph), 7.13 (m, 3, Ph).
ReO2(CH2CMe3)3. ReO2(CH2CMe3)2Cl(py) was produced in
situ by reacting ReO2(CH2CMe3)2Br(py) (0.199 g, 0.38 mmol)
with AgCl (0.110 g, 0.76 mmol) in CH2Cl2 (20 mL). The
mixture was stirred at 23 °C for 12 h. The solvent was then
removed in vacuo, and the residue was extracted with toluene
(1 × 10 mL, 2 × 5 mL). The red extracts, containing ReO2(CH2-
CMe3)2Cl(py), were combined and cooled to -5 °C. A colorless
solution of Zn(CH2CMe3)2 (0.160 g, 0.77 mmol) in toluene (5
mL) was then very slowly added to the cold solution via a
liquid-dropping funnel. After the addition was completed, the
reaction mixture was stirred at -5 °C for 30 min and then
warmed to room temperature. The mixture was then stripped
in vacuo. Sublimation from the residue in vacuo (45 °C, 10-3
mmHg) gave an orange powder on an H2O-cooled cold finger
(yield 0.130 g, 79%). Spectroscopic data was published
previously.8c
Hz, CH2CMe3), 1.81 (s, 2, CH2SiMe3), 0.96 (s, 18, CH2CMe3),
0.05 (s, 9, CH2SiMe3). 13C{1H} NMR (CD2Cl2, 23 °C): δ 72.7
(s, 2, CH2CMe3), 45.1 (s, 1, CH2SiMe3), 35.9 (s, 2, CH2CMe3),
31.8 (s, 6, CH2CMe3), 1.89 (s, 3, CH2SiMe3). 13C{1H} NMR
(CD2Cl2, -86 °C): δ 72.0 (s, 2, CH2CMe3), 44.6 (s, 1, CH2SiMe3),
34.9 (s, 2, CH2CMe3), 30.6 (s, 6, CH2CMe3), 0.43 (s, 3, CH2-
SiMe3). IR (Nujol, CsI, cm-1): ν(RedO) 992 s and 945 s.
ReO2(CH2CMe3)2P h . ReO2(CH2CMe3)2Br(py) (0.200 g, 0.38
mmol) was dissolved in toluene (20 mL), and the resulting red
solution was cooled to 0 °C. ZnPh2 (0.085 g, 0.38 mmol) in
toluene (15 mL) was slowly added to the cold solution via a
liquid-dropping funnel. After the addition was completed, the
mixture was warmed to room temperature and then stirred
for 30 min. Oxygen-free water (0.2 mL) was added to the
mixture, producing a cloudy solution. The mixture was cooled
to -20 °C to freeze the excess water and then cold filtered.
The filtrate was stripped under vacuum. Sublimation from
the residue (23 °C, 10-3 mmHg) gave an orange solid on an
H2O-cooled cold finger (yield 0.155 g, 92%). Anal. Calcd for
C
16H27O2Re: C, 43.92; H, 6.22. Found: C, 43.94; H, 6.27.
1H NMR (CD3CN): δ 7.30 (m, 2, Ph (meta)), 7.05 (m, 2, Ph
(ortho)), 6.97 (m, 1, Ph (para)), 3.42 (s, 4, CH2CMe3), 1.07 (s,
18, CH2CMe3). 13C{1H} NMR (CDCl3): δ 131.0 (s, 2, Ph
(meta)), 130.5 (s, 2, Ph (ortho)), 124.1 (s, 1, Ph (para)), 75.9 (s,
2, CH2CMe3), 36.4 (s, 2, CH2CMe3), 31.8 (s, 6, CH2CMe3). IR
(Nujol, CsI, cm-1): ν(RedO) 987 s and 945 s.
ReO2(CHCMe3)(CH2CMe3). ReO2(CH2CMe3)3 (0.179 g,
0.41 mmol) was dissolved in pyridine (20 mL). The orange
solution was photolyzed with a medium-pressure mercury
lamp at 23 °C for 1.5 h. The color gradually changed to deep
red. The volatile components were removed under vacuum.
A yellow solid sublimed from the residue (40 °C, 10-3 mmHg)
onto a dry ice-cooled cold finger (yield 0.114 g, 76%). Anal.
Calcd for C10H21O2Re: C, 33.41; H, 5.89. Found: C, 33.40; H,
5.87.
ReO2(CH2CMe3)2Me. ReO2(CH2CMe3)2Cl(py) (0.180 g, 0.38
mmol) was dissolved in toluene (20 mL), and the red solution
was cooled to -40 °C. ZnMe2 (0.036 g, 0.38 mmol) in toluene
(5 mL) was slowly added to the cold solution via a liquid-
dropping funnel. A white solid formed during the addition.
After the addition was completed, the mixture was warmed
to room temperature and then filtered. The filtrate was
carefully stripped, leaving an oily residue. The oil was further
dried under vacuum at 0 °C for 5 h. Sublimation/distillation
from the oil in vacuo (23 °C, 10-3 mmHg) gave an orange solid
on a CO2-cooled cold finger (yield 0.122 g, 86%). The solid
melts near room temperature. Anal. Calcd for C11H25O2Re:
C, 35.18; H, 6.71. Found: C, 35.04; H, 6.68.
1H NMR (C7D8): δ 12.07 (s, 1, CHCMe3), 2.86 and 2.63 (d
of an AB q, 2, J HH ) 14.3 Hz, CH2CMe3), 0.96 (s, 9, CHCMe3),
0.95 (s, 9, CH2CMe3). 13C NMR (C7D8): δ 283.3 (d, 1, J CH
)
138 Hz, CHCMe3), 45.3 (s, 1, CHCMe3), 38.5 (t, 1, J CH ) 130
Hz, CH2CMe3), 32.1 (q, 3, J CH ) 127 Hz, CHCMe3), 31.3 (s, 1,
CH2CMe3), 29.9 (q, 3, J CH ) 127 Hz, CH2CMe3). IR (Nujol,
CsI, cm-1): ν(RedO) 986 s and 947 s.
ReO2(CHCMe3)(CH2CMe3)(qu in ). ReO2(CH2CMe3)3 (0.413
g, 0.96 mmol) was dissolved in pyridine (20 mL). The orange
solution was photolyzed with a medium-pressure mercury
lamp at 23 °C for 1 h. The color gradually changed to deep
red. Quinuclidine (0.106 g, 0.96 mmol) was added to the red
solution, and the mixture was stirred for 2 h. The volatile
components were then removed in vacuo from the mixture,
and the residue was redissolved in a minimum amount of
acetonitrile. Slow cooling of the acetonitrile solution to -40
°C gave yellow needles, which were isolated by decanting the
mother liquor via a cannula. The crystals were washed with
a small amount of cold (-40 °C) acetonitrile and dried under
vacuum (yield 0.244 g, 54%). A satisfactory carbon analysis
was not obtained. Anal. Calcd for C17H34NO2Re: C, 43.38;
H, 7.28; N, 2.98. Found: C, 44.17; H, 7.33; N, 2.87.
1H NMR (C6D6): δ 3.05 (s, 4, CH2CMe3), 1.51 (s, 3, Me), 1.07
(s, 18, CH2CMe3). 13C{1H} NMR (C6D6): δ 71.4 (s, 2, CH2-
CMe3), 35.5 (s, 2, CH2CMe3), 33.2 (s, 1, Me), 31.63 (s, 6,
CH2CMe3). IR (neat, CsI, cm-1): ν(RedO) 992 s and 946 s.
R eO2(CH 2CMe3)2(CH 2SiMe3). ReO2(CH2CMe3)2Br(py)
(0.130 g, 0.25 mmol) was dissolved in toluene (20 mL), and
the resulting red solution was cooled to 0 °C. Zn(CH2SiMe3)2
(0.084 g, 0.35 mmol) in toluene (5 mL) was slowly added to
the cold solution via a liquid-dropping funnel. After the
addition was completed, the mixture was stirred at 0 °C for
30 min, warmed to room temperature, and then stirred for
another 30 min. Oxygen-free water (0.5 mL) was then added
to the mixture, giving a cloudy solution. The cloudy solution
was cooled to -20 °C to freeze the excess water and then cold
filtered. The filtrate was stripped under vacuum. Sublimation
from the residue (23 °C, 10-3 mmHg) gave an orange solid on
an H2O-cooled cold finger (yield 0.095 g, 85%). Anal. Calcd
for C14H33SiO2Re: C, 37.56; H, 7.43. Found: C, 37.43; H, 7.28.
1H NMR (C6D6): δ 12.64 (s, 1, CHCMe3), 2.51 and 2.24 (d
of an AB q, 2, J HH ) 13.7 Hz, CH2CMe3), 1.25 (s, 9, CHCMe3),
1.05 (s, 9, CH2CMe3), 2.65 (m, 6, quin (R)), 1.34 (m, 1, quin
(γ)), 1.11 (m, 6, quin (â)). 13C NMR (C6D6): δ 291 (d, J CH
)
137 Hz, CHCMe3), 49.0 (t, 3, J CH ) 140 Hz, quin (R)), 45.1 (s,
1, CHCMe3), 42.9 (t, 1, J CH ) 128 Hz, CH2CMe3), 32.9 (q, 3,
J CH ) 126 Hz, CHCMe3), 29.9 (q, 3, J CH ) 127 Hz, CH2CMe3),
26.6 (t, 3, J CH ) 128 Hz, quin (â)), 21.3 (d, 1, J CH ) 135 Hz,
quin (γ)). IR (CsI, Nujol, cm-1): v(RedO) 946 s and 903 s.
ReO2(CH2CMe3)(p y)x. ReO2(CH2CMe3)2Ph (0.410 g, 0.94
mmol) was dissolved in pyridine (20 mL). The orange solution
was heated at 70 °C for 2 h in the dark. The color gradually
changed to deep red. The reaction mixture was reduced in
volume in vacuo (to ≈3 mL) and then cooled to -20 °C. This
produced red crystals which were isolated by removing the
1H NMR (CD2Cl2, 23 °C): δ 3.25 (s, 4, CH2CMe3), 1.84 (s, 2,
CH2SiMe3), 1.08 (s, 18, CH2CMe3), 0.17 (s, 9, CH2SiMe3). 1H
NMR (CD2Cl2, -86 °C): δ 3.20 and 3.13 (AB q, 4, J HH ) 13.8
(23) ZnMe2 was prepared according to the method described in:
Wierda, D. A. Ph.D. Dissertation, Harvard University, 1990. Schrock,
R. R.; Fellman, J . D. J . Am. Chem. Soc. 1978, 100, 3359. Moorehouse,
S.; Wilkinson, G. J . Chem. Soc. 1974, 2187.

1030 Organometallics, Vol. 15, No. 3, 1996
Cai et al.
Ta ble 5. Cr ysta l Da ta Su m m a r y for ReO2(CH2CMe3)2P h , ReO2(CH2CMe3)(p y)3, ReO2(CHCMe3)(CH2CMe3),
a n d ReO2(CHCMe3)(CH2CMe3)(qu in )
ReO2(CH2CMe3)2Ph
ReO2(CHCMe3)(CH2CMe3) ReO2(CHCMe3)(CH2CMe3)(quin)
ReO2(CH2CMe3)(py)3
diffractometer
radiation type
wavelength, Å
color of cryst/habit
empirical formula
cryst dimens, mm
space group
temp, °C
Nicolet R3m/V
Mo KR (monochromated) Mo KR (monochromated)
0.710 73
Nicolet R3m/V
Nicolet R3m/V
Mo KR (monochromated)
0.710 73
Nicolet R3m/V
Mo KR (monochromated)
0.710 73
0.710 73
yellow-orange blocks
yellow needles
C10H21O2Re
0.15 × 0.20 × 0.25
Pbca
yellow blocks
C17H34NO2Re
0.20 × 0.22 × 0.25
Ph1
red plates
C
16H27O2Re
C20H26N3O2Re
0.10 × 0.13 × 0.19
P21/n
0.34 × 0.60 × 0.62
P21/c
-50(1)
-80(1)
-80(1)
-50(1)
cell dimens
a, Å
b, Å
10.244(3)
11.004(2)
15.861(4)
11.038(2)
20.168(4)
11.290(2)
6.1657(15)
10.036(2)
16.012(4)
79.35(2)
82.23(2)
89.29(2)
2
965
1.62
63.87
9.708(2)
18.670(3)
11.319(1)
c, Å
R, deg
â, deg
107.17(2)
95.39(1)
γ, deg
Z (molecules/cell)
4
8
4
V, Å3
1708
1.70
2513
1.90
97.76
θ-2θ
4-50
h,-k,l (+Friedel)
3678
2042
1.71
60.47
θ-2θ
4-50
d
calcd, g cm-3
abs coeff, cm-1
scan type
72.06
θ-2θ
4-50
(h,-k,l
3334
θ-2θ
2θ range, deg
data collcd
reflcns collcd
4-50
h,(k,(l
-h,(k,(l
4207
3766
no. of unique reflcns 3015
1646
3403
2688
no. with Fo > nσ(Fo) 2499 (n ) 6)
1369 (n ) 4)
0.0313
0.0384
0.0394
1.38
3264 (n ) 6)
0.0279
0.0317
0.0416
2.28
1956 (n ) 4)
0.0446
0.0482
0.0542
1.13
a
Rmerg
0.0301
0.0385
0.0502
0.85
R(F)b
Rw(F)c
“goodness of fit” d
a
Rmerg ) [(∑NΣw(Fo(mean) - Fo)2)/(∑(N - 1)∑wFo2)]1/2, where the inner summations are over the N equivalent reflections averaged to
give F(mean) and the outer summations are over all unique observed reflections. R ) ∑||Fo| - |Fc||/∑|Fo|. c Rw ) [∑w(|Fo| - |Fc|)2/
b
∑w|Fo| ]1/2, w ) [σ2(F) + gF2]-1
.
GOF ) [∑w(||Fo| - |Fc||)2/(nobs - nparams)]1/2
.
2
d
mother liquor via a cannula. Drying the crystals at 23 °C in
vacuo for 12 h gave a value of 1.9 for x (on this basis, the yield
is 74%). The sample prepared for combustion analysis was
recrystallized from pyridine at -20 °C and then dried under
vacuum at -20 °C for 2 h. A stoichiometry of ReO2(CH2CMe3)-
(py)2.8 was calculated for this sample by using 1H NMR. Anal.
Calcd for C20H26N3O2Re: C, 45.61; H, 4.98; N, 7.98. Found:
C, 43.73; H, 4.40; N, 7.59.
1H NMR (CD2Cl2, -70 °C): δ 9.05 (m, 2, py (ortho)), 8.76
(m, 4, py (ortho)), 7.56 (m, 1, py (para)), 7.42 (m, 2, py (para)),
7.27 (m, 2, py (meta)), 7.27 (m, 4, py (para)). 13C{1H} NMR
(CD2Cl2, -70 °C): δ 149.4 (s, 4, py (ortho)), 146.3 (s, 2, py
(meta)), 137.6 (s, 1, py (para)), 137.5 (s, 2, py (para)), 123.4 (s,
4, py (meta)), 123.3 (s, 2, py (meta)), 37.7 (s, 1, CH2CMe3), 35.4
(s, 1, CH2CMe3), 31.7 (s, 3, CH2CMe3). IR (Nujol, CsI, cm-1):
ν(RedO) 803 s.
ReO2(CH2CMe3)(MeCtCMe). ReO2(CH2CMe3)(py)1.9 (0.113
g, 0.26 mmol) was dissolved in a mixture of pyridine (0.2 mL)
and toluene (10 mL). The red solution was frozen in liquid
nitrogen. 2-Butyne (1.5 mmol) was then condensed into the
reaction flask via a calibrated vacuum manifold. The mixture
was slowly warmed to room temperature and then stirred for
8 h. The color changed to light brown. The mixture was then
stripped in vacuo. Sublimation from the residue in vacuo (50
°C, 10-3 mmHg) gave a yellow solid on an H2O-cooled cold
finger (yield 0.056 g, 64%). Anal. Calcd for C9H17O2Re: C,
31.48; H, 4.99. Found: C, 31.78; H, 5.07.
vacuo (70 °C, 10-3 mmHg) produced a yellow solid on an H2O-
cooled cold finger (0.066 g, 65%). An unsatisfactory carbon
analysis was obtained in two attempts. Anal. Calcd for
C
13H17O2Re: C, 39.89; H, 4.38. Found: C, 41.94 and 41.38;
H, 4.62 and 4.57.
Two isomers, in the ratio of 5:1, are present in solution. 1H
NMR (major isomer, CDCl3): δ 9.10 (s, 1, HCtCPh), 7.82-
7.53 (m, 5, Ph), 3.85 (s, 2, CH2CMe3), 1.19 (s, 9, CH2CMe3). 1H
NMR (minor isomer, CDCl3): δ 9.66 (s, 1, HCtCPh), 7.53-
7.39 (m, 5, Ph), 3.68 (s, 2, CH2CMe3), 1.12 (s, 9, CH2CMe3).
13C NMR (major product, CDCl3): δ 140.1 (m, 1, HCtCPh),
133.6 (d, 1, J CH ) 223 Hz, HCtCPh), 133.1 (d of t, 2, J CH
)
2
163 Hz, J CH ) 6.5 Hz, Ph (meta)), 131.8 (d of t, 1, J CH ) 162
2
Hz, J CH ) 7.5 Hz, Ph (para)), 129.1 (d of d, 2, J CH ) 154 Hz,
2J CH ) 6.9 Hz, Ph (ortho)), 126.9 (t, 1, 2J CH ) 7.5 Hz, Ph (ipso)),
49.7 (t, 1, J CH ) 133 Hz, CH2CMe3), 32.3 (s, 1, CH2CMe3), 31.7
(q, 3, J CH ) 124 Hz, CH2CMe3). 13C NMR (minor product,
2
CDCl3): δ 130.1 (d of t, 1, J CH ) 163 Hz, J CH ) 6.9 Hz, Ph
2
(para)), 129.7 (d of t, 2, J CH ) 162 Hz, J CH ) 6.85 Hz, Ph
2
(meta)), 128.8 (d of d, 2, J CH ) 155 Hz, J CH ) 7.55 Hz, Ph
(ortho)), 123.8 (d, 1, J CH ) 223 Hz, HCtCPh), 50.6 (t, 1, CH2-
CMe3), 32.5 (s, 1, CH2CMe3), 31.5 (q, 3, CH2CMe3). IR (Nujol,
CsI, cm-1): ν(RedO) 971 s and 933 s, ν(CtC) 1738 m.
X-r a y Cr ysta llogr a p h y. X-ray data were collected on a
Nicolet R3m/V four-circle diffractometer equipped with a LT-1
low-temperature device. Data collection was controlled using
the Nicolet P3 program. Unit cell symmetry was checked with
the program XCELL. Raw diffractometer data was processed
with the program XDISK. The structures were solved by use
of the SHELXTL-PLUS package of programs. Drawings were
produced using the Nicolet program XP.
In each case, the crystal was attached to a 0.30 mm glass
fiber with a minimum amount of silicon grease. The crystal
was frozen in place by immersing it in a cold nitrogen stream
from the low-temperature attachment. A crystal data sum-
mary is presented in Table 5.
1H NMR (CDCl3): δ 3.47 (s, 2, CH2CMe3), 2.89 (q, 3, 5J HH
)
5
1.03 Hz, MeCtCMe), 2.58 (q, 3, J HH ) 1.03 Hz, MeCtCMe),
1.15 (s, 9, CH2CMe3). 13C{1H} NMR (CDCl3): δ 138.8 (s, 1,
MeCtCMe), 130.7 (s, 1, MeCtCMe), 48.5 (s, 1, CH2CMe3), 31.9
(s, 1, CH2CMe3), 31.6 (s, 3, CH2CMe3), 14.6 (s, 1, MeCtCMe),
6.96 (s, 1, MeCtCMe). IR (Nujol, CsI, cm-1): ν(RedO) 966 s
and 921 s, ν(CtC) 1836 w.
ReO2(CH2CMe3)(HCtCP h ). ReO2(CH2CMe3)(py)1.9 (0.114
g, 0.26 mmol) was dissolved in phenyl acetylene (0.2 mL). The
reaction mixture was stirred at 23 °C for 8 h and then stripped
under vacuum. Sublimation from the light brown residue in
ReO2(CH2CMe3)2P h . The crystals for study were grown
by low temperature crystallization from a saturated acetoni-

Rhenium(VII) Oxo-Alkyl Complexes
Organometallics, Vol. 15, No. 3, 1996 1031
Ta ble 6. Atom ic Coor d in a tes (×105) a n d
Equ iva len t Isotr op ic Disp la cem en t P a r a m eter s (Å2
x 104) for ReO2(CH2CMe3)2P h a
Ta ble 8. Atom ic Coor d in a tes (×104) a n d
Equ iva len t Isotr op ic Disp la cem en t P a r a m eter s (Å2
x 103) for ReO2(CHCMe3)(CH2CMe3)(qu in )a
atom
x
y
z
U(eq)
atom
x
y
z
U(eq)
Re
72189(3)
1973(2)
12031(50)
-8362(49)
14412(64)
18211(65)
8192(85)
21838(76)
29419(76)
-10834(64)
-15438(67)
-18427(75)
-6270(79)
-27213(68)
2763(52)
31409(2)
186(1)
Re
O(1)
O(2)
C(1)
2424(1)
3719(7)
-832(1)
387(4)
2371(1)
1568(3)
2598(3)
2928(4)
3633(4)
4360(6)
3327(5)
3945(4)
3321(4)
3212(4)
3129(9)
2449(6)
4008(6)
1195(3)
553(4)
20(1)
28(1)
27(1)
25(2)
27(2)
42(3)
39(2)
30(2)
27(2)
30(2)
82(5)
73(4)
61(4)
22(1)
28(2)
31(2)
31(2)
33(2)
29(2)
31(2)
26(2)
O(1)
O(2)
C(1)
C(10)
C(11)
C(12)
C(13)
C(2)
C(20)
C(21)
C(22)
C(23)
C(3)
82825(49)
77528(57)
62426(70)
71597(76)
71923(98)
86069(74)
64269(89)
69046(66)
82529(76)
93609(71)
87407(87)
78332(82)
50971(70)
46503(77)
32859(82)
23390(83)
27636(78)
41412(72)
28507(32)
39714(30)
38223(41)
47585(43)
54191(46)
47985(44)
49952(51)
20743(40)
19030(44)
27380(46)
13541(51)
13501(49)
24100(44)
17423(41)
12537(43)
14347(51)
20848(51)
25725(44)
330(18)
359(19)
230(22)
263(24)
439(32)
301(25)
383(30)
201(21)
261(24)
304(25)
372(28)
309(26)
164(20)
270(23)
319(26)
332(27)
313(27)
250(23)
-210(6)
4488(10)
4429(10)
5412(17)
5913(12)
2136(10)
1982(11)
490(11)
-1474(4)
-1952(6)
-3160(6)
-2656(12)
-4253(7)
-3732(7)
433(6)
1678(6)
1299(10)
2741(8)
2328(10)
-2059(5)
-1291(6)
-1882(7)
-3274(6)
-4095(6)
-3457(6)
-3045(7)
-2169(7)
C(10)
C(11)
C(12)
C(13)
C(2)
C(20)
C(21)
C(22)
C(23)
N
C(31)
C(32)
C(33)
C(34)
C(35)
C(36)
C(37)
-1832(15)
1384(20)
469(21)
2553(8)
C(4)
C(5)
C(6)
C(7)
11551(66)
12274(70)
4374(71)
-4092(80)
-5072(68)
1234(10)
1477(12)
2579(11)
1270(12)
1567(11)
4913(11)
4816(10)
-278(4)
-108(4)
699(4)
1468(4)
68(4)
C(8)
a
Equivalent isotropic U defined as one-third of the trace of the
orthogonalized Uij tensor.
769(4)
a
Equivalent isotropic U defined as one-third of the trace of the
orthogonalized Uij tensor.
Ta ble 7. Atom ic Coor d in a tes (×104) a n d
Equ iva len t Isotr op ic Disp la cem en t P a r a m eter s (Å2
x 103) for ReO2(CHCMe3)(CH2CMe3)a
(PSICOR) based on ψ scans from 6 reflections near ø ) 90°
and Lorentz and polarization corrections were applied to the
data.
atom
x
y
z
U(eq)
Systematic absences uniquely determined the space group
to be Pbca. A Patterson synthesis readily revealed the position
of the Re atom. Standard difference map techniques were used
to find the remaining non-hydrogen atoms. After all of the
non-hydrogen atoms were located and refined anisotropically,
a difference map revealed all of the hydrogen atom positions.
An attempt was made to refine the hydrogen atoms isotropi-
cally, but during the refinement one hydrogen attached to each
of C(2) and C(21) did not refine well. Therefore, all of the
hydrogen atoms attached to these two carbon atoms were
placed in calculated positions (Uiso(H) ) 1.2Uiso(C); dC-H ) 0.96
Å) for refinement. Refinement was performed to convergence
with this model. The final difference map contained six peaks
of height greater than 1.0 e Å-3 located within 1.23 Å of the
rhenium [1.56 e Å-3 (max)]. All other peaks were less than
Re
O(2)
O(1)
C(2)
1523(1)
225(7)
2645(7)
949(9)
2212(9)
405(10)
1790(9)
465(14)
2016(16)
1378(11)
-678(10)
-26(13)
2566(17)
6151(1)
6483(3)
5812(3)
5409(5)
6690(4)
4762(4)
7234(4)
7396(8)
6999(6)
4384(6)
4924(5)
4340(6)
7857(6)
8220(1)
8765(7)
9065(6)
7023(8)
7055(8)
7559(10)
6246(10)
6398(15)
4973(10)
8269(11)
8363(9)
6528(12)
6490(12)
24(1)
38(3)
37(3)
22(3)
20(3)
26(3)
26(3)
55(5)
46(5)
35(4)
30(4)
37(5)
49(5)
C(1)
C(20)
C(10)
C(13)
C(11)
C(22)
C(21)
C(23)
C(12)
a
Equivalent isotropic U defined as one-third of the trace of the
orthogonalized Uij tensor.
trile solution (-20 °C; 2 days). Removal of the mother liquor
via a cannula yielded yellow-orange blocks. The crystals were
handled in air for the short time necessary for selection and
mounting. Atomic coordinates are given in Table 6. The
intensities of three check reflections were measured after every
60 reflections. A linear decay correction based on a decay of
29% during the 40 h of data collection was applied to the data.
An absorption correction using the program XEMP, which was
based on ψ scans from 5 reflections near ø ) 90°, and Lorentz
and polarization corrections were applied to the data.
Systematic absences uniquely determined the space group
to be P21/c. A Patterson synthesis readily revealed the position
of the rhenium atom. Standard difference map techniques
were used to find the remaining non-hydrogen atoms. The
hydrogen atoms were placed on the carbon atoms in calculated
positions [Uiso(H) ) 1.2Uiso(C); dC-H ) 0.96 Å] for refinement.
Refinement was performed to convergence with this model.
The final difference map contained eight peaks of height
greater than 1.0 e Å-3 located within 1.04 Å of the rhenium
[1.99 e Å-3 (max)].
0.69 e Å-3
.
ReO2(CHCMe3)(CH2CMe3)(qu in ). The crystals for study
were grown by slowly cooling a saturated acetonitrile solution
(-20 °C; 12 h). Removal of the mother liquor via a cannula
yielded yellow blocks. The crystals were handled for short
periods of time in air. Atomic coordinates are presented in
Table 8. The intensities of three check reflections were
measured after every 60 reflections; the crystal did not decay
significantly during the 45 h of data collection. A semiem-
pirical absorption correction (PSICOR) based on scans from 8
reflections near ø ) 90° and Lorentz and polarization correc-
tions were applied to the data.
A Patterson synthesis readily revealed the position of the
Re atom. Standard difference map techniques were used to
find the remaining non-hydrogen atoms. After all of the non-
hydrogen atoms were located and refined anisotropically, a
difference map revealed all of the hydrogen atom positions.
An attempt was made to refine the hydrogen atoms isotropi-
cally, but during the refinement one hydrogen attached to each
of C(21), C(22), and C(35) did not refine well. Therefore, all
of the hydrogen atoms attached to these carbon atoms were
placed in calculated positions (Uiso(H) ) 1.2Uiso(C); dC-H ) 0.96
Å) for refinement. Refinement was performed to convergence
with this model. The final difference map contained one peak
of height 1.97 e Å-3 located 0.88 Å from the rhenium. All other
ReO2(CHCMe3)(CH2CMe3). The crystals for study were
grown by slowly cooling a saturated acetonitrile solution (-20
°C; 24 h). Removal of the mother liquor via a cannula yielded
yellow needles. The crystals were handled for short periods
of time in air. Atomic coordinates are presented in Table 7.
The intensities of three check reflections were measured after
every 60 reflections; the crystal did not decay significantly
during the 78 h of data collection. An absorption correction
peaks were less than 1.0 e Å-3
.
ReO2(CH2CMe3)(p y)3. The crystals for study were grown
by slowly cooling a saturated pyridine solution (-20 °C; 2

1032 Organometallics, Vol. 15, No. 3, 1996
Cai et al.
Ta ble 9. Atom ic Coor d in a tes (×104) a n d
intensities of three check reflections were measured after every
60 reflections. A linear decay correction based on a decay of
19% during the 63 h of data collection was applied to the data.
An absorption correction using the program XEMP, which was
based on scans from 6 reflections near ø ) 90°, and Lorentz
and polarization corrections were applied to the data.
Systematic absences uniquely determined the space group
to be P21/n. A Patterson synthesis readily revealed the
position of the rhenium atom. Standard difference map
techniques were used to find the remaining non-hydrogen
atoms. The neopentyl group was found to be disordered over
two positions with refinement indicating a 66/34 distribution.
The hydrogen atoms were placed on the carbon atoms in
calculated positions [Uiso(H) ) 1.2Uiso(C); dC-H ) 0.96 Å] for
refinement. Refinement was performed to convergence with
this model. The final difference map contained two peaks of
height greater than 1.0 e Å-3 located within 1.16 Å of Re (1.34
e Å-3 (max)).
Equ iva len t Isotr op ic Disp la cem en t P a r a m eter s (Å2
a
x 103) for ReO2(CH2CMe3)(p y)3
atom
Re
x
y
z
U(eq)
797(1)
820(10)
590(9)
3196(1)
3439(6)
3160(5)
4304(6)
3668(6)
2782(6)
4507(9)
5133(10)
5573(11)
5363(11)
4739(9)
3870(8)
4158(11)
4257(10)
4078(10)
3768(8)
2647(8)
2418(8)
2365(9)
2511(9)
2721(9)
2221(7)
2163(9)
1459(5)
1307(11)
1556(20)
952(9)
2747(1)
4240(8)
1203(8)
30(1)
52(4)
42(3)
37(4)
38(4)
33(4)
54(6)
72(8)
98(11)
91(10)
64(7)
52(6)
80(9)
92(12)
79(9)
47(6)
43(6)
53(7)
60(7)
55(7)
50(6)
54(11)
67(21)
42(6)
50(10)
79(23)
62(12)
59(21)
64(11)
97(33)
O(1)
O(2)
N(1)
N(2)
-327(11)
2793(11)
-1273(11)
-815(15)
-1545(19)
-1767(19)
-1226(21)
-525(17)
3569(16)
4868(21)
5379(21)
4609(18)
3354(16)
-2062(14)
-3437(15)
-4008(15)
-3162(15)
-1847(16)
2020(17)
1567(35)
1568(11)
581(18)
2451(11)
2690(11)
2791(10)
1359(15)
1151(20)
2097(30)
3144(23)
3319(17)
3662(16)
3654(24)
2571(31)
1579(23)
1651(16)
1803(14)
1823(18)
2886(19)
3894(17)
3853(15)
2816(21)
3437(22)
2773(10)
1681(16)
1717(23)
2801(20)
2311(30)
3861(16)
3569(23)
N(3)
C(11)
C(12)
C(13)
C(14)
C(15)
C(21)
C(22)
C(23)
C(24)
C(25)
C(31)
C(32)
C(33)
C(34)
C(35)
C(4A)b
C(4B)c
C(40)
C(41A)b
C(41B)c
C(42A)b
C(42B)c
C(43A)b
C(43B)c
Ack n ow led gm en t for support is made to the Petro-
leum Research Fund, administered by the American
Chemical Society. D.M.H. also wishes to acknowledge
support from the Robert A. Welch Foundation and the
Alfred P. Sloan Foundation (1992-1994) in the final
stages of this research.
2432(31)
2784(18)
122(19)
780(21)
2226(39)
Su p p or tin g In for m a tion Ava ila ble: Tables of anisotro-
pic thermal parameters, calculated H atom coordinates, and
bond lengths and bond angles, a stick drawing of ReO2(CH2-
CMe3)(py)3 showing the disordered neopentyl ligand, and
packing diagrams for ReO2(CH2CMe3)2Ph, ReO2(CHCMe3)(CH2-
CMe3), ReO2(CHCMe3)(CH2CMe3)(quin), and ReO2(CH2CMe3)-
(py)3 (30 pages). Ordering information is given on any current
masthead page. Tables of observed and calculated structure
factors can be obtained from the authors.
1250(18)
1293(12)
881(11)
a
Equivalent isotropic U defined as one-third of the trace of the
b
orthogonalized Uij tensor. Site occupancy factor (SOF) associated
with the disordered neopentyl group, SOF ) 0.66. c SOF ) 0.34.
days). Removal of the supernatant solution via a cannula
yielded red plates. The crystals were handled under a nitrogen
atmosphere. Atomic coordinates are presented iin Table 9. The
OM950761O