Rhodium(I) mixed CO/phosphine/amine complexes: synthesis, structure, and reactivity

Article abstract of DOI:10.1021/om980419m

A series of new complexes of the general formula Rh(CO)(Cl)(PPh₃XNRR′R″) have been prepared via the bridge-splitting reactions of [Rh(μ-Cl)(CO)(PPh₃)]₂ with primary, secondary, and tertiary amine ligands. The Rh(I) complexes, Rh(CO)(Cl)(PPh₃)(H₂NCy) (3) and Rh(CO)(Cl)(PPh₃)(HNEt₂) (6) were crystallographically characterized and were found to possess a local square-planar geometry with a triphenylphosphine ligand trans to the amine. There is evidence for inter- and intramolecular hydrogen bonding between the amine hydrogen and the chloride ligand in 3 and 6. Complex 6 adds CX₄ (X = Cl, Br, I) resulting in the formation of Rh(III) anionic complexes of the type [RhCl_nX_4-n(PPh₃)(CO)]-(NH₂R ₂)⁺. The complex [RhCl₄(PPh₃)(CO)]-(NH₂Et₂) ⁺-1/2 C₆H₆ (19) was characterized by X-ray diffraction and was found to crystallize in the monoclinic C2/c space group. The crystal structure of complex 20, which is synthesized from the reaction of 6 with CBr₄, indicates that the compound corresponds to the formula [RhBr_2.85Cl_1.15(CO)(PPh₃)]-(H ₂NEt₂)⁺-1/2 C₆H₆. Rh(CO)(Cl)(PPh₃)(HNEt₂) catalyzes hydrosilation of 1-hexene and polymerization of styrene and methyl methacrylate in the presence of perhaloalkanes.

Full text of DOI:10.1021/om980419m

4966
Organometallics 1998, 17, 4966-4975
Rh od iu m (I) Mixed CO/P h osp h in e/Am in e Com p lexes:
Syn th esis, Str u ctu r e, a n d Rea ctivity
Maria G. L. Petrucci, Anne-Marie Lebuis, and Ashok K. Kakkar*
Department of Chemistry, McGill University, 801 Sherbrooke Street West,
Montreal, Quebec H3A 2K6, Canada
Received May 26, 1998
A series of new complexes of the general formula Rh(CO)(Cl)(PPh3)(NRR′R′′) have been
prepared via the bridge-splitting reactions of [Rh(µ-Cl)(CO)(PPh3)]2 with primary, secondary,
and tertiary amine ligands. The Rh(I) complexes, Rh(CO)(Cl)(PPh3)(H2NCy) (3) and Rh-
(CO)(Cl)(PPh3)(HNEt2) (6) were crystallographically characterized and were found to possess
a local square-planar geometry with a triphenylphosphine ligand trans to the amine. There
is evidence for inter- and intramolecular hydrogen bonding between the amine hydrogen
and the chloride ligand in 3 and 6. Complex 6 adds CX4 (X ) Cl, Br, I) resulting in the
formation of Rh(III) anionic complexes of the type [RhClnX4-n(PPh3)(CO)]-(NH2R2)+. The
complex [RhCl4(PPh3)(CO)]-(NH2Et2)+‚1/2 C6H6 (19) was characterized by X-ray diffraction
and was found to crystallize in the monoclinic C2/c space group. The crystal structure of
complex 20, which is synthesized from the reaction of 6 with CBr4, indicates that the
compound corresponds to the formula [RhBr2.85Cl1.15(CO)(PPh3)]-(H2NEt2)+‚1/2 C6H6. Rh-
(CO)(Cl)(PPh3)(HNEt2) catalyzes hydrosilation of 1-hexene and polymerization of styrene
and methyl methacrylate in the presence of perhaloalkanes.
In tr od u ction
CCl4. The hydrosilation reaction with RhCl(CO)(PPh3)-
(NEt2H) is complete in 30 min at 60 °C, while a similar
reaction with RhCl(CO)(PPh3)2 requires refluxing for 6
days and gives a lower yield of the hydrosilated product.
The polymerization of methyl methacrylate proceeds in
a living fashion.
The Rh(I) complexes such as RhCl(CO)(PMe3)2 are
known to oxidatively add a X-CX3 (X ) Cl, Br) bond
that is subsequently added across the double bond of
alkenes (the Kharasch reaction).3 A similar reaction of
RhCl(CO)(PPh3)(NEt2H) with CX4 (X ) Cl, Br, I) does
not lead to the oxidative addition product and, instead,
produces Rh(III) anionic complexes of the type [RhCl4-
(CO)(PPh3)]-[NR2H2]+ and [RhClnX4-n(CO)(PPh3)]--
[NR2H2]+. The anionic complexes [RhCl4(CO)(PPh3)]--
[NEt2H2]+‚1/2C6H6 and [RhCl1.15Br2.85(CO)(PPh3)]--
[NEt2H2]+ have been structurally characterized.
Rh(I) complexes of the type RhCl(PPh3)3 and RhCl-
(CO)(PPh3)2 are probably among the oldest and most
extensively studied homogeneous catalysts and are
known to promote a variety of organic transformations.1
In these sterically crowded molecules with 16 electrons
at the metal center, ligand dissociation is an important
first step in the catalytic cycle leading to coordinatively
unsaturated active species.1 We were intrigued by the
possibility of having a weakly coordinating ligand such
as an amine in a position directly opposite that of PPh3,
a ligand with a strong σ-donor trans effect.2 The latter
is expected to enhance the lability of the amine ligand
and may offer rich and intriguing chemistry of these
complexes. We report herein synthesis and a detailed
study of Rh(I) complexes containing Cl, CO, PPh3, and
a primary, secondary, or tertiary amine ligand. Such
stable d8-Rh(I) complexes, RhCl(CO)(PPh3)(NRR′R′′),
are easily accessible via bridge-splitting reactions of [Rh-
(CO)(PPh3)(µ-Cl)]2 with amines. A single-crystal struc-
ture determination of RhCl(CO)(PPh3)(NEt2H) and RhCl-
(CO)(PPh3)(NCyH2) showed that the Rh(I) centers in
these complexes have square-planar geometry with the
amine ligand trans to a phosphine. The bound amine
in RhCl(CO)(PPh3)(NEt2H) is sufficiently labile and
undergoes ligand displacement reactions under mild
reaction conditions. The complex RhCl(CO)(PPh3)-
(NEt2H) is an efficient catalyst for (i) hydrosilation of
1-hexene and (ii) polymerization of styrene and methyl
methacrylate in the presence of haloalkanes such as
Resu lts a n d Discu ssion
Syn th esis a n d Ch a r a cter iza tion of Rh (I) Mixed
CO/P P h 3/Am in e Com p lexes. The Rh(I) complexes
employed in this study were synthesized by the bridge-
splitting reactions4 of the appropriate rhodium halide
dimer, [Rh(µ-Cl)(CO)(PPh3)]2, with 2 equiv of either
primary, secondary, or tertiary amine ligand (Scheme
1).
Using this methodology, the monoamine adducts
containing primary amines RhCl(CO)(PPh3)(H2NR) [R
(3) Cable, C. J .; Adams, H.; Bailey, N. A.; Crosby, J .; White, C. J .
Chem. Soc., Chem. Commun. 1991, 165.
(4) (a) Steele, D. F.; Stephenson, T. A. J . Chem. Soc. 1972, 2161. (b)
Rollmann, L. D. Inorg. Chim. Acta 1972, 6, 137. (c) Deganello, G.;
Uguagliati, P. Crociani, B.; Belluco, U. J . Chem. Soc. A 1969, 2726.
(d) Vallarino, L. M.; Sheargold, S. W. Inorg. Chim. Acta 1979, 36, 243.
(e) Hartley, F. R.; Murray, S. G.; Potter, D. M. J . Organomet. Chem.
1983, 254, 119.
(1) Dickson, R. S. Homogeneous Catalysis with Compounds of
Rhodium and Iridium; D. Reidel Publ. Co.: Dordrecth, 1985.
(2) Collman, J . P.; Hegedus, L. S.; Norton, J . R.; Finke, R. G.
Principles and Applications of Organotransition Metal Chemistry;
University Science Books: Mill Valley, CA, 1987.
10.1021/om980419m CCC: $15.00 © 1998 American Chemical Society
Publication on Web 10/16/1998

Rh(I) Mixed CO/ Phosphine/ Amine Complexes
Organometallics, Vol. 17, No. 23, 1998 4967
Sch em e 1
Ta ble 1. 31P {1H} NMR a n d F T-IR Sp ectr a l Da ta for
Rh (I) Am in e Com p lexes
31P{1H} δ J (103Rh-31P) νCO cm-1
complexes
(ppm)
(Hz)
(KBr)
RhCl(CO)(PPh3)
[NH2Et] (1)
46.0 (d)
156
1967
RhCl(CO)(PPh3)[NH2
(CH2)5CH3] (2)
RhCl(CO)(PPh3)
[NH2Cy] (3)
RhCl(CO)(PPh3)[NH2C
(Me2)CH2CMe3] (4)
RhCl(CO)(PPh3)[HN
(CH3)2] (5)
RhCl(CO)(PPh3)[HNEt2]
(6)
RhCl(CO)(PPh3)
[NHPr2] (7)
RhCl(CO)(PPh3)[HN(CH
(CH3)2)2] (8)
RhCl(CO)(PPh3)
[NHBu2] (9)
RhCl(CO)(PPh3)[HN
(CH2CH(CH3)2)2] (10)
RhCl(CO)(PPh3)[HN
(CH2C6H5)2] (11)
RhCl(CO)(PPh3)[HN
(C5H10)] (12)
RhCl(CO)(PPh3)[NH
(C4H8O)] (13)
RhCl(CO)(PPh3)[HN(C5H9) 46.1 (d)
NC5H10] (14)
RhCl(CO)(PPh3)[HNEt
(CH3)] (15)
RhCl(CO)(PPh3)[HN(CH3)
(CH2C6H5)] (16)
RhCl(CO)(PPh3)[HN(CH3)
(CH2(C14H9))] (17)
RhCl(CO)(PPh3)
45.2 (d)
44.5 (d)
45.8 (d)
45.3 (d)
45.3 (d)
44.8 (d)
45.1 (d)
44.3 (d)
44.4 (d)
46.0 (d)
46.2 (d)
46.4 (d)
154
155
157
151
153
153
158
153
155
157
150
152
150
162
154
152
176
1969
1969
1971
1964
1954
1962
1961
1965
1968
1956
1960
1962
1957
1956
1965
1966
1971
F igu r e 1. Variable-temperature 1H NMR spectra (270
MHz, toluene-d8, CH2 region) of compound 6.
The 1H NMR spectrum of RhCl(CO)(PPh3)(NEt2H) (6)
in C6D6 at room temperature showed two broad mul-
tiplets at 2.39 and 2.63 ppm in a 1:1 ratio for the CH2
protons on the ethyl substituents of the amine ligand.
The latter indicates that the two CH2 groups are
diastereotopic. Complex 6 has Cs symmetry, and we
were intrigued by the possibility of making these
methylene hydrogens’ chemical shift equivalent at
higher temperatures. Heating the sample in toluene-
d8 from 25 to 110 °C resulted in the peaks for the two
CH2 groups merging together (Figure 1). The complete
collapsing of the peaks, however, may require higher
temperatures, and finding a solvent that has a suf-
ficiently high boiling point and that does not react with
the Rh(I) complexes proved to be difficult. A similar
pattern was observed for the other complexes containing
secondary amine ligands such as 7, 8, 9, 10, and 11.
Sin gle-Cr ysta l Str u ctu r a l Ch a r a cter iza tion of
R h Cl(CO)(P P h 3)(H N(C2H 5)2) (6) a n d R h Cl(CO)-
(P P h 3)(H2NC6H11)‚1/2C6H6 (3). Yellow sticks of com-
pounds 3 and 6 that were suitable for single-crystal
X-ray diffraction studies were obtained from crystal-
lization using a mixture of benzene/hexanes solutions.
An ORTEP drawing of 6 is shown in Figure 2, and the
relevant bond lengths and angles are shown in Table
3. The compound crystallizes in a Pbca space group
with eight molecules in an orthorhombic unit cell. The
molecule has a square-planar geometry about rhodium,
with the diethylamine ligand trans to triphenylphos-
phine. The carbonyl ligand is close to linear about the
carbon atom, with a Rh-C(1)-O angle of 175.2(8)°. The
45.1 (d)
45.7 (d)
46.2 (d)
47.8 (d)
[NEt3] (18)
) C2H5 (1), (CH2)5CH3 (2), C6H11 (3), C(CH3)2CH2C-
(CH3)3 (4)], secondary amines RhCl(CO)(PPh3)(NRR′H)
[R ) R′) CH3 (5), C2H5 (6), C3H7 (7), CH(CH3)2 (8), C4H9
(9), CH2CH(CH3)2 (10), CH2(C6H5) (11), C5H10 (12),
C4H8O (13), C5H9NC5H10 (14); R ) CH3, R′ ) C2H5 (15),
R ) CH3, R′ ) CH2(C6H5) (16), R ) CH3, R′ ) CH2-
(C14H9) (17)], and tertiary amine RhCl(CO)(PPh3)-
(N(C2H5)3) (18) were isolated in very good yields. These
yellow-colored complexes were found to be soluble in a
wide range of organic solvents and were characterized
by routine spectroscopic and analytical techniques.
The 31P{1H} NMR and infrared spectral data for these
complexes are presented in Table 1. These complexes
typically displayed a doublet in their 31P{1H} NMR
spectra at ∼46 ppm with the Rh-P coupling constant
of ∼155 Hz, with the exception of the tertiary amine
complex 18, which gave a J Rh-P value of 176 Hz. Their
FT-IR spectra showed νCO stretching frequencies in the
range 1954-1971 cm-1. The lowest value was observed
for the diethylamine complex 6, and the highest one for
the tert-octylamine (4) and triethylamine (18) com-
plexes.

4968 Organometallics, Vol. 17, No. 23, 1998
Petrucci et al.
Ta ble 3. Selected Bon d Dista n ces a n d An gles for
Rh Cl(CO)P P h 3(NEt2H), 6, Rh Cl(CO)P P h 3(NCyH2),
3, a n d Rh (CO)(Cl)(P P h 3)2
Rh(CO)(Cl)(PPh3)- Rh(CO)(Cl)(PPh3)- Rh(CO)(Cl)-
a
(HNEt2) (6)
(H2NCy) (3)
(PPh3)2
Distances (Å)b
Rh-C(1)
Rh-N
1.783(8)
2.183(6)
2.257(2)
2.364(2)
1.825(7)
1.831(7)
1.836(6)
1.148(8)
1.470(9)
1.478(11)
0.91
1.802(2)
2.173(5)
2.264(5)
2.384(6)
1.835(2)
1.829(2)
1.838(2)
1.144(3)
1.485(5)
1.759 (1)
Rh-P
2.328(1)
2.380(2)
1.826(4)
1.821(4)
1.826(4)
1.14(1)
Rh-Cl
P-C(31)
P-C(21)
P-C(11)
O-C(1)
N-C(2)
N-C(4)
N-H
0.90
Angles (deg)b
C(1)-Rh-N
C(1)-Rh-P
N-Rh-P
92.3(3)
91.0(2)
174.6(2)
174.3(3)
84.8(2)
91.7(7)
175.2(8)
85.8(3)
91.6(7)
172.8(12)
176.7(7)
91.1(3)
F igu r e 2. ORTEP drawing of 6. Thermal ellipsoids are
drawn at the 50% probability level. Hydrogen atoms with
the exception of N-H have been omitted for clarity.
92.1(2)
C(1)-Rh-Cl
N-Rh-Cl
P-Rh-Cl
179.7(3)
Ta ble 2. Exp er im en ta l Da ta for th e X-r a y
Diffr a ction Stu d ies of th e Rh (I) Am in e Com p lexes
92.7(2)
178.4(2)
87.8(5)
177.2(9)
Rh-C(1)-O
RhCl(CO)PPh3-
(NEt2H) (6)
RhCl(CO)PPh3-
a
b
Reference 2. Estimated standard deviations in the least
significant figure are given in parentheses.
(NCyH2)a (3)
mol formula
mol wt
color
cryst system
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
C
23H26ClNOPRh
C28H31ClNOPRh
566.87
yellow
monoclinic
C2/c
33.6292(10)
9.07880(10)
24.03910(10)
90
134.3054(6)
90
5252.29(6)
8
501.78
yellow
orthorhombic
Pbca
15.805(3)
26.006(3)
11.150(2)
90
(8) Å) in 6 is slightly longer than that in the bis-
(phosphine) complex (1.759(1) Å). These results suggest,
as expected, that the amine ligand is a weaker donor
than a phosphine, which forces the metal center to
withdraw more electron density from the bound phos-
phine, and there is less π-back-donation to the CO
ligand.
90
90
4582.9(13)
8
1.454
The solid-state FT-IR spectrum of 6 displayed a sharp
N-H stretching vibration at 3247 cm-1 with a shoulder
at 3439 cm-1, in addition to the νCO stretch at 1954
cm-1. This suggests that there may be two types of
amine groups, free and hydrogen bonded.6 A number
of possibilities for the formation of the R-H-X-R′
bonds can be considered:7 (i) intermolecular hydrogen
bonding (a) between the nitrogen atom of a bound amine
ligand and the amine ligand of another complex (type
I, Scheme 2); and (b) with the chloride ligand of another
complex (type II, Scheme 2); (ii) intramolecular hydro-
gen bonding between the hydrogen atom of the amine
ligand and the chloride ligand (type III, Scheme 2); with
the rhodium center (type IV, Scheme 2) or with the
oxygen atom of the carbonyl ligand (type V, Scheme 2).
An examination of the packing diagram and of inter-
atomic contacts of 6 suggests that intramolecular hy-
drogen bonding of type III and intermolecular hydrogen
bonding of type V are involved in the formation of
hydrogen bonds in which the hydrogen atom on the
bound amine ligand interacts with the chloride and the
carbonyl oxygen of a neighboring complex. The hydro-
gen-to-Cl and -O distances in this complex were found
to be 2.636 and 2.392 Å, respectively. A typical hydro-
gen bond distance in NH‚‚‚O systems is in the range
Z
D
calcd, g cm-1
1.434
F(000)
2048
0.252
0.81, 0.69
2328
0.822
0.93, 0.66
µ, mm-1
transmission factors:
max., min.
temp, K
293(2)
293(2)
cryst size, mm
diffractometer
radiation
θ range, deg
no. of measured rflns
no. of independent
0.45 × 0.32 × 0.20 0.38 × 0.20 × 0.12
Rigaku AFC6-S
Mo KR
Siemens P4, CCD
Mo KR
2-25
30 368
1.69-26.39
21 249
4039 (0.073)
5304 (0.0274)
rflns (Rint
)
no. of refined params 258
356
no. of restraints
R1 (obs/all data)
wR2 (obs/all data)
GOF
0
39
0.056/0.085
0.133/0.121
1.156
0.024/0.060
0.033/0.066
1.027
largest diff peak, e/Å3 +0.578, -0.510
+0.401, -0.546
a
Compound crystallizes with 1/2 molecule of benzene.
N-Rh-P angle of 174.6(2)° reveals a slight shift from
an idealized square-planar geometry. The angles be-
tween N-Rh-C(1)O, P-Rh-C(1)O, and P-Rh-Cl ap-
proach 90°; however, the largest discrepancy is found
in the N-Rh-Cl angle that has a value of 84.8(2)°. A
comparison of the Rh-P and Rh-C(1) distances in 6 to
those in trans-RhCl(CO)(PPh3)2 (Table 3) indicates that
the Rh-P bond distance of 2.257(2) Å in 6 is much
shorter than that of 2.328(1) Å in trans-RhCl(CO)-
(PPh3)2.5 Similarly, the Rh-C(1) bond length (1.783-
(6) (a) Chatt, J .; Duncanson, L. A.; Venanzi, L. M. J . Inorg. Nucl.
Chem. 1958, 8, 67. (b) Chatt, J .; Duncanson, L. A.; Venanzi, L. M. J .
Chem. Soc. 1956, 2712. (c) Chatt, J .; Duncanson, L. A.; Venanzi, L. M.
J . Chem. Soc. 1955, 4461.
(7) (a) Eisenstein, O.; Yao, W.; Crabtree, R. H. Inorg. Chim. Acta
1997, 254, 105. (b) Widenhoefer, R. A.; Buchwald, S. L. Organometallics
1996, 15, 3534.
(5) Chen, Y. J .; Wang, J . C.; Wang, Y. Acta Crystallogr. 1991, C47,
2441.

Rh(I) Mixed CO/ Phosphine/ Amine Complexes
Organometallics, Vol. 17, No. 23, 1998 4969
Sch em e 2. P oten tia l Hyd r ogen Bon d in g Mod es
for Rh (CO)(Cl)(P P h 3)(NEt2H)
F igu r e 3. Packing diagram of 6 drawn at the 30%
probability level. Hydrogen atoms with the exception of
N-H have been omitted for clarity.
1.60-2.40 Å.8 Taking into account the difference in van
der Waals radii of transition metals relative to oxygen7a,9
should result in an additional increase of 0.6-0.85 Å
with an expected hydrogen bond distance in the range
2.20-3.25 Å. The hydrogen-to-acceptor distances at
2.636 Å for H‚‚‚Cl and 2.392 Å for H‚‚‚OtC fall within
this range.
Intermolecular hydrogen bonding between the bound
amine and CO ligands in 6 may be responsible for the
lower CO stretching frequency in this compound com-
pared to the other mixed CO/PPh3/amine complexes
(Table 1) and with the bisphosphine complex trans-
RhCl(CO)(PPh3)2 (1960 cm-1).5
Compound 3 containing a primary amine ligand,
RhCl(CO)(PPh3)(H2NCy), crystallizes in a C2/c (mono-
clinic) space group with eight molecules in the unit cell.
The complex displays a local geometry (Figure 4) that
is similar to that described above for 6. The Rh-C(1)O
bond distance of 1.802(2) Å is longer than that in the
bis(phosphine)complex (1.759(1) Å) and even that in
complex 6 (1.783(8) Å) (Table 3). As in 6, the Rh-P
distance of 2.264(5) Å is shorter than that in trans-RhCl-
(CO)(PPh3)2 (2.328(1) Å). The bond angles in 3 are
similar to those for 6.
The packing diagram of 3 (Figure 5) also suggests
intramolecular hydrogen bonding of type III similar to
complex 6 with a H-Cl bond length of 2.532 Å. There
may also be some intermolecular hydrogen bonding
between the amine hydrogen and a ligated chloride of
a neighboring molecule (2.561 Å) in the solid-state
structure.
Am in e Exch a n ge in Rh (I) Mixed CO/P h osp h in e/
Am in e Com p lexes. The amine ligand in the above-
mentioned Rh(I) complexes can be easily displaced with
strong donor phosphine ligands. For example, the
reaction of 1 equiv of RhCl(CO)(PPh3)(HN(C2H5)2) (6)
with 1 equiv of triphenylphosphine (PPh3) in benzene
led to an immediate and exclusive formation of trans-
RhCl(CO)(PPh3)2 with the liberation of diethylamine.
When equimolar amounts of 6 and trimethylphosphine
(PMe3) were reacted, it resulted in the formation of a
F igu r e 4. PLATON drawing of the structure 3. Thermal
ellipsoids are drawn at the 40% probability level. The
asymmetric unit also contains 1/2 molecule of benzene.
Hydrogen atoms with the exception of N-H have been
omitted for clarity.
mixture of RhCl(CO)(PMe3)2 and RhCl(CO)(PPh3)-
(PMe3). A similar reaction with 2 equiv of PMe3 yielded
RhCl(CO)(PMe3)2 as the only product. The latter can
be explained by taking into account the stronger electron-
donating ability of PMe3 than both amine and PPh3
ligands, and it exchanges with both of these ligands in
6.
R ea ct ivit y of R h (I) Am in e Com p lexes t ow a r d
Ha loa lk a n es. It is known that perhaloalkanes can be
added to alkenes (the Kharasch reaction)10 in the
presence of Rh(I) complexes and may proceed via initial
oxidative addition of the haloalkane to rhodium followed
by a rapid transfer to the coordinated alkene.11 It has
been shown that RhCl(CO)(PMe3)2 oxidatively adds Br-
CCl3, and the resulting product, RhClBr(CCl3)(CO)-
(PMe3)2, has been structurally characterized.3 A similar
reaction of RhCl(CO)(PPh3)(HN(C2H5)2) (6) and CX4 (X
) Cl, Br, I) in benzene did not lead to the formation of
(10) (a) Kharasch, M. S.; Reinmuth, O.; Urry, W. H. J . Am. Chem.
Soc. 1947, 69, 1105. (b) Asscher, M.; Vofsi, D. J . Chem. Soc. 1963, 3921.
(c) Freidlina, R. K.; Chukovskaya, E. C. Synthesis 1974, 477. (d) Davis,
R.; Groves, I. F. J . Chem. Soc., Dalton Trans. 1982, 2281. (e) Grigg,
R.; Ramasubba, A.; Scott, R. M.; Stevenson, P. J . Chem. Soc., Perkin
Trans. 1 1987, 1515. (f) Murai, S.; Sugise, R.; Sonoda, N. Angew. Chem.,
Int. Ed. Engl. 1981, 20, 475.
(8) J effrey, G. A.; Saenger, W. Hydrogen Bonding in Biological
Structures; Springer: Berlin, 1991.
(9) Brammer, L.; Zhao, D. Organometallics 1994, 13, 1545.
(11) (a) Chalk, A. J . J . Organomet. Chem. 1970, 21, 207. (b)
Haszeldine, R. N.; Parish, R. V.; Parry, D. J . J . Chem. Soc. (A) 1969,
683.

4970 Organometallics, Vol. 17, No. 23, 1998
Petrucci et al.
Ta ble 4. In ter - a n d In tr a m olecu la r Hyd r ogen a Bon d Dista n ces (Å) a n d An gles (d eg) for
Rh Cl(CO)(P P h 3)(H2NCy) (3) a n d Rh Cl(CO)(P P h 3)(HN(C2H5)2) (6)
donor-H‚‚‚acceptor
D‚‚‚A
D-H
H‚‚‚A
D-H‚‚‚A
H-bonding
6
3
N-H‚‚‚Oa
N-H‚‚‚Cl
N-H‚‚‚Cl
N-H‚‚‚Cla
3.251(9)
3.067(8)
2.950(5)
3.346(5)
0.910
0.910
0.900
0.900
2.392
2.636
2.532
2.561
157.4(6)
109.9(5)
108.97(7)
146.12(10)
intermolecular
intramolecular
intermolecular
intramolecular
a
Distances involving H atoms have no error associated since the H position is calculated and not refined. Oa: 0.5 - x, 1 - y, 0.5 + z.
Cla: 0.5 - x, 0.5 + y, 0.5 - z.
Ta ble 5. Exp er im en ta l Da ta for th e X-r a y Diffr a ction Stu d ies of Rh (III) Am in e Com p lexes
[RhCl4(CO)PPh3]-(NEt2H2)+ (19)a
[RhBr2.85Cl1.15(CO)PPh3]-(NEt2H2)+ (20)a
mol formula
mol wt
color
C26H30Cl14NOPRh
648.22
yellow
C26H30Br2.85Cl1.15NOPRh
774.91
red
cryst syst
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
monoclinic
C2/c
21.343(4)
9.793(2)
29.547(4)
90
110.85(2)
90
5771(2)
8
monoclinic
C2/c
21.5826(3)
9.93590(10)
29.39560 (10)
90
111.3868(8)
90
5869.59(10)
8
Z
D
calcd, g cm-1
1.492
1.754
F(000)
2632
1.030
0.99, 0.89
3042 3192
4.602
1.00, 0.98
µ, mm-1
transmission factor:
max., min.
temp, K
293(2)
293(2)
cryst size, mm
diffractometer
radiation
0.32 × 0.32 × 0.09
Rigaku AFC6-S
Mo KR
0.17 × 0.14 × 0.10
Siemens Smart CCD
Mo KR
θ range, deg
2.04-24.97
1.48-28.65
no. of measured rflns
independent rflns (Rint
no. of refined params
no. of restraints
R1 (obs/all data)
wR2 (obs/all data)
GOF
19 666
5081 (0.138)
308
33 346
7559 (0.0553)
325
)
16
3
0.0881/0.0959
0.1887/0.1192
1.088
0.0376/0.0630
0.0670/0.0715
1.047
largest diff peak, e/Å3
+0.712, -0.524
+0.547, -0.496
a
Compound crystallizes with 1/2 molecule of benzene.
the oxidative-addition product, but instead yielded air-
stable Rh(III) anionic salts, [RhCl4(CO)(PPh3)]-(H2NEt2)+,
19, [RhBr3Cl(CO)(PPh3)]-(H2NEt2)+, 20, and [RhI3-
Cl(CO)(PPh3)]-(H2NEt2)+, 21, respectively. Complexes
19 and 20 have been structurally characterized.
Sin gle-Cr ysta l Str u ctu r e Ch a r a cter iza tion of
[Rh Cl4(CO)(P P h 3)]-(H2NEt2)+‚1/2C6H6 (19) a n d [Rh -
Br 2.85Cl1.15(CO)(P P h 3)]-(H2NEt2)+‚1/2C6H6 (20). Yel-
low crystals of [RhCl4(CO)(PPh3)]-(H2NEt2)+‚1/2C6H6
(19) suitable for analysis were grown from C6H6 at 50
°C. The ORTEP diagram of 19 is shown in Figure 6,
the crystal data are presented in Table 5, and selected
bond lengths and angles are given in Table 6. Complex
19 crystallizes in a C2/c space group with eight mol-
ecules in a monoclinic unit cell. The core geometry of
the anion is octahedral with the triphenylphosphine and
carbonyl ligands positioned in a cis orientation, and the
protonated amine acts as the counterion. The carbonyl
ligand is slightly bent about the carbon atom with a
Rh-C(1)-O angle of 174.0(9)°. The large bond angle
of 96.0(3)° for P-Rh-C(1)O is probably due to the steric
repulsion of the triphenylphosphine ligand, resulting in
a marked decrease for the OC(1)-Rh-Cl(4) (83.5(3)°)
and OC(1)-Rh-Cl(2) (172.3(3)°) angles. The angles
between OC(1)-Rh-Cl(1), OC(1)-Rh-Cl(3), P-Rh-Cl-
F igu r e 5. Packing diagram (solvent omitted) of 3.
(1), P-Rh-Cl(2), P-Rh-Cl(3), and P-Rh-Cl(4) ap-
proach those expected for an idealized octahedral ge-
ometry. A comparison of the Rh-C(1) distance in 19
to that of 6 indicates that the Rh-C(1) bond length of
1.851(11) Å in 19 is slightly longer than that in 6 (1.783-
(8) Å). Similarly, the Rh-P bond distance in 19 (2.323-
(2) Å) is significantly longer than that found in the Rh(I)
complex 6 (2.257(2) Å). As expected, the presence of four
bound chloride ligands decreases the metal’s ability to
back-donate to the CO ligand, thus lengthening the Rh-

Rh(I) Mixed CO/ Phosphine/ Amine Complexes
Organometallics, Vol. 17, No. 23, 1998 4971
Ta ble 6. Selected Bon d Dista n ces a n d An gles for
Rh (III) An ion ic Com p lexesa
[RhCl4(CO)(PPh3)]- [RhBr2.85Cl1.15(CO)(PPh3)]-
(NEt2H2)+ (19)b
(NEt2H2)+ (20)b
Distances (Å)
Rh-C(1)O
Rh-P
P-C(31)
P-C(21)
P-C(11)
O-C(1)
Rh-Cl(1)
Rh-Cl(2)
Rh-Cl(3)
Rh-Cl(4)
Rh-Br(1)
Rh-Br(2)
Rh-Br(3)
Rh-Br(4)
1.851(11)
2.323(2)
1.827(8)
1.835(9)
1.815(8)
1.062(4)
2.345(2)
2.357(2)
2.348(3)
2.409(3)
1.905(4)
2.3308(9)
1.834(3)
1.825(3)
1.829(3)
1.132(10)
2.35(2)
2.34(2)
2.36(2)
2.411(11)
2.498(2)
2.4974(14)
2.483(3)
2.520(3)
F igu r e 6. ORTEP view of the anion and cation of
[RhCl4(CO)(PPh3)]-(H2NEt2)+‚1/2C6H6 (19). The asymmetric
unit also contains 1/2 molecule of benzene. Thermal el-
lipsoids are drawn at the 40% probability level. Hydrogen
atoms are represented as spheres of arbitrary size.
Angles (deg)
C(1)-Rh-P
96.0(3)
87.1(3)
172.3(3)
88.3(3)
83.5(3)
174.0(9)
96.11(1)
88.0(10)
171.1(7)
88.4970
76.5(2)
175.6(4)
88.0(2)
171.30(13)
86.0(2)
C(1)-Rh-Cl(1)
C(1)-Rh-Cl(2)
C(1)-Rh-Cl(3)
C(1)-Rh-Cl(4)
Rh-C(1)-O
C(1)-Rh-Br(1)
C(1)-Rh-Br(2)
C(1)-Rh-Br(3)
C(1)-Rh-Br(4)
P-Rh-Cl(1)
P-Rh-Cl(2)
P-Rh-Cl(3)
P-Rh-Cl(4)
P-Rh-Br(1)
P-Rh-Br(2)
P-Rh-Br(3)
P-Rh-Br(4)
83.10(12)
89.6(10)
91.5(7)
92.54(9)
91.57(9)
89.4(9)
92.9(8)
178.41(10)
171.9(2)
89.04(13)
92.44(7)
93.16(13)
178.30(6)
a
Estimated standard deviations in the least significant figure
b
are given in parentheses. Compound crystallizes with 1/2 mol-
F igu r e 7. ORTEP view of the anion and cation of
[RhBr2.85Cl1.15(CO)(PPh3)]-(H2NEt2)+‚1/2C6H6 (20). The asym-
metric unit also contains 1/2 molecule of benzene. Thermal
ellipsoids are drawn at the 40% probability level. Hydrogen
atoms are represented as spheres of arbitrary size.
ecule of benzene.
C(1) bond length. This also has a pronounced effect on
the C(1)-O bond distance (1.062(4) Å), which is shorter
than that in 6 (1.148(8) Å). The Rh-Cl bond distances
decrease on going from the Rh(I) to the Rh(III) complex,
with the exception of the chloride ligand trans to a
carbonyl that has a bond length of 2.357(2) Å, similar
to the Rh-Cl bond distance in RhCl(CO)(PPh3)(HN-
(C2H5)2) (2.364(2) Å).
The carbonyl ligand is close to linear about the carbon
atom with a Rh-C(1)O angle of 175.6(4)°. The Rh-P,
Rh-C(1)O, and C(1)-O bond distances are longer than
for compound 19 (Table 6). The bond angles between
C(1)-Rh-Cl(1)/C(1)-Rh-Br(1), C(1)-Rh-Cl(3)/C(1)-
Rh-Br(3), P-Rh-Cl(1)/P-Rh-Br(1), P-Rh-Cl(2)/P-
Rh-Br(2), and P-Rh-Cl(3)/P-Rh-Br(3) approach ide-
alized octahedral geometry. The C(1)-Rh-Cl(2)/C(1)-
Rh-Br(2) and C(1)-Rh-Cl(4)/C(1)-Rh-Br(4) bond
angles at 171.1(7)°/171.3(13)° and 76.5(2)°/83.1(12)° are
shorter than those present in 19. The Cl/Br ligands
trans to triphenylphosphine exhibit longer Rh-X bond
lengths than all other halogens. This trend is also
present in compound 19.
Red prisms of 20 suitable for X-ray analysis crystal-
lized directly out of benzene after 24 h at ambient
temperature. Compound 20 crystallizes ([RhBr2.85
-
Cl1.15(CO)(PPh3)]-(H2NEt2)+‚1/2C6H6, Figure 7, Tables
5 and 6) in a C2/c space group with eight molecules in
the monoclinic unit cell. The geometry of the molecule
is similar to 19; however, the halogen atoms bound to
rhodium show disorder, each site being occupied by a
mixture of chlorine and bromine atoms. The final
occupancy factors for the Cl/Br sites indicate a nonsto-
ichiometric compound with average positions of Br 2.85
and Cl 1.15. Imposing occupancies of Br atoms to a total
of 3.00 and 1.00 for Cl led to a significantly higher
disagreement factor as well as negative residues near
the Br sites. Complex 20 ([RhBr2.85Cl1.15(CO)(PPh3)]-(H2-
NEt2)+‚1/2C6H6) is a mixture mainly of the [RhBr3Cl(CO)-
(PPh3)]-(H2NEt2)+ and [RhBr2Cl2(CO)(PPh3)]-(H2NEt2)+,
but may also contain other compositions such as
[RhBr4(CO)(PPh3)]-(H2NEt2)+ and [RhCl4(CO)(PPh3)]--
(H2NEt2)+.
The lability of the diethylamine ligand in 6 may be
responsible for the formation of the Rh(III) anionic salts.
For example, the displacement of the diethylamine
ligand by a chlorine in CCl4 may lead to the formation
of the Rh(I) complex RhCl(CO)(PPh3)(Cl-CCl3), which
might rearrange to give the Rh(III) complex, RhCl2-
(CCl3)(CO)(PPh3). The latter may undergo a reaction
with another molecule of CCl4, yielding RhCl3(CO)-
(PPh3), which reacts further with CCl4 and diethylamine
to yield the Rh(III) salt [RhCl4(CO)(PPh3)]-(H2NEt2)+.

4972 Organometallics, Vol. 17, No. 23, 1998
Petrucci et al.
Hyd r osilyla tion of 1-Hexen e. Rh(I) complexes
have been studied as catalysts for the hydrosilylation
of olefins11 and give rise to relatively little isomerization
in the product distribution. In view of the similarities
of the RhCl(CO)(PPh3)2 complex to RhCl(CO)(PPh3)(HN-
(C2H5)2) (6), an investigation was undertaken of some
of the possible differences between these two catalysts.
The hydrosilation of 1-hexene with triphenylsilane or
phenyldimethylsilane in the presence of catalytic
amounts of 6 and refluxing at 60 °C for 30 min in
benzene led to the formation of the terminal n-hexyl
product in 85-89% yield as determined by 1H NMR and
GC-MS. It has been demonstrated that the hydrosi-
lation of 1-hexene with triphenylsilane can be catalyzed
using RhCl(CO)(PPh3)2 upon refluxing at 60 °C for 6
days with a 75% yield of the product silane.11b The
turnover efficiency of this reaction is 1.81 h-1, which is
significantly lower than with complex 6 at 86.5 h-1 for
triphenylsilane and 155.8 h-1 for phenyldimethylsilane.
There is no difference in catalyst selectivity between
RhCl(CO)(PPh3)2 and complex 6; however, in terms of
activity, 6 is significantly more active, producing a
greater amount of the n-hexyl product in a shorter
reaction time. The hydrosilation of 1-pentene with
phenyldimethylsilane in the presence of Wilkinson’s
catalyst11a (RhCl(PPh3)3) resulted in a turnover ef-
ficiency of 22.2 h-1. The silane and olefin concentra-
tions, reaction conditions, and yields for the latter
reaction were similar to those with complex 6 for the
hydrosilation of 1-hexene. The first step in the hydrosi-
lation of olefins involves ligand dissociation followed by
the oxidative addition of the silane and coordination of
the alkene.11 In the reaction with 6, the initial step may
involve dissociation of the diethylamine ligand since it
is more labile than the phosphine ligand and may be
responsible for an overall increase in the reaction rate.
P olym er iza tion of Styr en e a n d Meth yl Meth -
a cr yla te Usin g Rh (I) Am in e Com p lexes. Metal
carbonyls in the presence of organohalides are known
to initiate the free radical polymerization of styrene and
methyl methacrylate (MMA).12 Low-valent metal com-
plexes such as trans-PtHCl(PPh3)2, trans-Rh(CO)Cl-
(PPh3)2, Pd(PPh3)4, RuCl2(PPh3)3, and NiBr2(PPh3)2, in
the presence of alkyl halides, have also been shown to
act as radical initiators in the polymerization of MMA
and styrene.13,14 We were intrigued by the possibility
of polymerizing MMA and styrene by Rh(I) mixed CO/
amine/phosphine complexes in the presence of perhalo-
alkanes. It was found that RhCl(CO)(PPh3)(HN(C2H5)2)
(6) in the presence of CCl4 was a very good catalyst for
the polymerization of MMA (Mn ) 6.6 × 104) and
styrene (Mn ) 6.1 × 103). The polymerization could not
be initiated with either 6 or [RhCl4(CO)(PPh3)]-(H2-
NEt2)+ alone under similar conditions. These results
suggest that the polymerization may proceed via a free
radical pathway in which the complex catalyzes the
activation of one of the carbon-chlorine bonds in carbon
tetrachloride to generate the trichloromethyl radical
(CCl3 ), which then adds to the carbon-carbon double
•
bond of the olefin, followed by the formation of the
olefin-CCl4 adduct with a terminal C-Cl bond.12,14
To examine the living nature of the methyl meth-
acrylate polymerization process,14c a fresh feed of MMA
was added to the reaction mixture when the initial
charge of the monomer had been consumed. The added
monomer was smoothly polymerized, and the Mn of the
polymer increased with each monomer addition. The
molecular weight distributions were not narrow ini-
tially; however, they became narrower as conversion
increased. This suggests that the polymerization of
MMA catalyzed by RhCl(CO)(PPh3)(HN(C2H5)2) in the
presence of CCl4 proceeds in a living fashion where the
Rh(I) complex acts as a redox initiator, reversibly
activating the covalent carbon-halogen bond in CCl4.
Con clu sion s
Stable d8-Rh(I) complexes containing mixed CO/
phosphine/amine ligands can be easily prepared form
the Rh(I) dimer, [Rh(µ-Cl)(CO)(PPh3)]2, and primary,
secondary, and tertiary amines via bridge-splitting
reactions. These complexes depict a typical square-
planar geometry at the rhodium center with the amine
ligand trans to triphenylphosphine, as evidenced by the
single-crystal structure determinations of RhCl(CO)-
(PPh3)(H2NCy) and RhCl(CO)(PPh3)(HN(C2H5)2). There
is evidence for intramolecular hydrogen bonding be-
tween the amine hydrogen and a bound chloride ligand.
The crystal structure of RhCl(CO)(PPh3)(H2NCy) also
suggests intermolecular hydrogen bonding between the
amine hydrogen and chloride ligand of another mol-
ecule, while that of the complex RhCl(CO)(PPh3)(HN-
(C2H5)2) suggests intermolecular hydrogen bonding
between the amine hydrogen and the carbonyl oxygen
of a neighboring molecule. The compound RhCl(CO)-
(PPh3)(HN(C2H5)2) does not yield an oxidative addition
product upon reacting with perhaloalkanes such as CX4,
but generates the Rh(III) anionic salt of the type
[RhCl4(CO)(PPh3)]-(H2NEt2)+, which has been structur-
ally characterized. RhCl(CO)(PPh3)(HN(C2H5)2) cata-
lyzes hydrosilation of 1-hexene and free radical polym-
erization of styrene and methyl methacrylate. The
preliminary results suggest that the polymerization of
methyl methacrylate by this complex in the presence
of CCl4 is a living polymerization.
Exp er im en ta l Section
Ma ter ia ls a n d Mea su r em en ts. All manipulations and
reactions were carried out under a nitrogen atmosphere either
using standard Schlenk techniques or in an Innovative Tech-
nology (Braun) Labmaster MB-150 drybox. Toluene, benzene,
and hexanes were stored under nitrogen after being distilled
over sodium. Amines used were dried and distilled over KOH
and degassed prior to use. Carbon tetrachloride was dried and
distilled over P2O5 before use. µ-Chloro(carbonyltriphenylphos-
phine)rhodium (I) dimer (1a ) was prepared and purified
according to literature methods.4a Unless otherwise specified,
all other reagents were obtained from the usual commercial
suppliers and used as received. NMR spectra were measured
on a J EOL 270 MHz spectrometer at ambient temperatures
unless otherwise specified. All NMR samples were prepared
under a nitrogen atmosphere in either C6D6 or CDCl3. Chemi-
cal shifts (ppm) reported are relative to tetramethylsilane as
(12) Sawamoto, M.; Kamigaito, M. TRIP 1996, 4 (11), 371.
(13) (a) Bamford, C. H.; Eastmond, G. C.; Hargreaves, K. Trans.
Faraday Soc. 1968, 64, 175. (b) Bamford, C. H.; Finch, C. A. Trans.
Faraday Soc. 1963, 59, 548.
(14) (a) Bamford, C. H.; Sakamoto, I. J . Chem. Soc., Faraday Trans.
1974, 170, 330. (b) Kameda, N.; Itagaki, N. Bull. Chem. Soc. J pn. 1973,
46, 2597. (c) Kato, M.; Kamigaito, M.; Sawamoto, M.; Higashimura,
T. Macromolecules 1995, 28, 1721. (d) Ando, T.; Kato, M.; Kamigaito,
M.; Sawamoto, M. Macromolecules 1996, 29, 1070.

Rh(I) Mixed CO/ Phosphine/ Amine Complexes
Organometallics, Vol. 17, No. 23, 1998 4973
an internal standard for 1H NMR spectra and to H3PO4 for
31P{1H} NMR spectra. Coupling constants (J ) are given in
hertz. Electron impact (EI) and fast atom bombardment (FAB)
mass spectra were obtained using a low-resolution KRATOS
MS25RSA spectrometer with xenon as the ionizing gas and
nitrobenzyl alcohol as the matrix. MALDI-TOF mass spectra
were obtained on a Kratos Kompact Maldi 3 v.4.0.0 spectrom-
eter using LiBr/didronel as the matrix. Infrared spectra were
recorded on a Bruker IFS-48 Fourier transform infrared
spectrometer using a standard resolution of 4 cm-1 for
transmission. Molecular weights of the polymers were ob-
tained on a Waters 441 Millipore GPC using polystyrene as
the internal standard. Elemental analyses were performed
by either Microanalytical Service Ltd. (Chemical Engineering),
Montreal, Quebec, or Guelph Chemical Laboratory, Guelph,
Ontario.
C6D6): δ 45.3 (d, J Rh-P ) 151 Hz). IR (KBr): νCO 1963.9 cm-1
.
FAB-MS: m/z 473.6. Anal. Calcd for 21H22PONClRh
C
(473.74): C, 53.24; H, 4.68; N, 2.96. Found: C, 53.11; H, 4.61;
N, 2.67.
Rh Cl(CO)(P P h 3)[HN(CH2CH3)2] (6). A solution of 1a (25
mg, 0.029 mmol) and diethylamine (6.04 µL, 0.058 mmol) in
toluene (10 mL) was stirred at room temperature for 1 h. The
resulting pale yellow solution was evaporated under vacuum
and washed with hexanes. A microcrystalline solid was
recrystallized from benzene and dried under vacuum to give
6 (28.3 mg, 97%). 1H NMR (270 MHz, C6D6): δ 1.34 (6H, t,
J H-H ) 7.2 Hz, CH2CH3), 2.39 (2H, m, J H-H ) 4.6 Hz, CH2-
CH3), 2.63 (2H, m, J H-H ) 4.6 Hz, CH2CH3), 3.31 (1H, br s,
NH), 7.01, 7.91, (15H, m, P(C6H5)3). 31P {1H} NMR (109 MHz,
C6D6): δ 45.3 (d, J Rh-P ) 153.4 Hz). IR (KBr): νCO 1954.4 cm-1
FAB-MS: m/z 501.82. Anal. Calcd for 23H26PONClRh
.
C
Rh Cl(CO)(P P h 3)[NH2(CH2CH3)] (1): Gen er a l P r oce-
d u r e. A solution of µ-chloro(carbonyltriphenylphosphine)-
rhodium (I) dimer (1a ) (40 mg, 0.0467 mmol) and ethylamine
(0.027 mL, 0.093 mmol) in toluene (10 mL) was stirred at room
temperature for 1 h. The resulting pale yellow solution was
(501.79): C, 55.05; H, 5.22; N, 2.79. Found: C, 55.16; H, 5.30;
N, 2.75.
R h Cl(CO)(P P h 3)[NH (CH 2CH 2CH 3)2] (7). Reaction of
dipropylamine (6.38 µL, 4.71 mg, 0.047 mmol) and 1a (20 mg,
0.0233 mmol) using a procedure analogous to the preparation
of 6 led to the isolation of 7 (23.2 mg, 94%) as a pale yellow
microcrystalline solid. 1H NMR (270 MHz, C6D6): δ 0.81 (3H,
t, J H-H ) 7.2 Hz, CH3), 1.87 (2H, m, J H-H ) 4.8 Hz CH2CH3),
2.14 (2H, m, J H-H ) 5.3 Hz, CH2CH3), 2.41 (2H, m, J H-H ) 6.9
Hz, CH2N), 2.76 (2H, m, J H-H ) 6.8 Hz, CH2N), 3.55 (1H, br
s, HN), 7.13, 7.98 (15H, m, P(C6H5)3). 31P {1H} NMR (109
MHz, C6D6): δ 44.8 (d, J Rh-P ) 153.5 Hz). IR (KBr): νCO
evaporated under vacuum and washed with hexanes.
A
microcrystalline solid was recrystallized from benzene and
dried under vacuum to give (1) (42.5 mg, 96%). 1H NMR (270
MHz, C6D6): δ 1.70 (3H, t, J H-H ) 6.9 Hz, CH3), 2.45 (2H, q,
J H-H ) 5.6 Hz, CH2N), 3.57 (2H, br s, H2N), 7.05, 7.95 (15H,
m, P(C6H5)3). 31P {1H} NMR (109 MHz, C6D6): δ 46.0 (d, J Rh-P
) 155.8 Hz). IR (KBr): νCO 1967.5 cm-1. FAB-MS: m/z 474.75.
Anal. Calcd for C21H22PONClRh (473.73): C, 53.24; H, 4.68;
N, 2.96. Found: C, 53.35; H, 4.91; N, 2.45.
1962.0 cm-1. FAB-MS: m/z 529.03. Anal. Calcd for C25H30
-
PONClRh (529.85): C, 56.67; H, 5.71; N, 2.64. Found: C,
56.90; H, 5.85; N, 2.81.
Rh Cl(CO)(P P h 3)[NH2(CH2)5CH3] (2). Reaction of hexyl-
amine (7.69 µL, 2.94 mg, 0.0583 mmol) and 1a (25 mg, 0.0292
mmol) using a procedure analogous to the preparation of 1
Rh Cl(CO)(P P h 3)[HN(CH(CH3)2)2] (8). Reaction of diiso-
propylamine (0.0119 mL, 8.64 mg, 0.085 mmol) and 1a (36.6
mg, 0.0427 mmol) using a procedure analogous to the prepara-
tion of 6 led to the isolation of 8 (43.9 mg, 97%) as a yellow
solid. 1H NMR (270 MHz, C6D6): δ 1.13 (6H, d, J H-H ) 6.3
Hz, CH(CH3)2), 1.42 (6H, d, J H-H ) 6.6 Hz, CH(CH3)2), 2.77
(2H, h, J H-H ) 6.3 Hz, CH(CH3)2), 3.82 (1H, br s, NH), 7.02,
7.90 (15H, m, P(C6H5)3). 31P {1H} NMR (109 MHz, C6D6): δ
45.1 (d, J Rh-P ) 158 Hz). IR (KBr): νCO 1961.0 cm-1. FAB-
MS: m/z 529.03. Anal. Calcd for C25H30PONClRh (529.85):
C, 56.67; H, 5.71; N, 2.64. Found: C, 56.52; H, 5.74; N, 2.58.
Rh Cl(CO)(P P h 3)[NH(CH2CH2CH2CH3)2] (9). Reaction of
dibutylamine (8.24 µL, 6.32 mg, 0.049 mmol) and 1a (21 mg,
0.0245 mmol) using a procedure analogous to the preparation
of 6 led to the isolation of 9 (25.8 mg, 94%) as a pale yellow
solid. 1H NMR (270 MHz, C6D6): δ 0.88 (3H, t, J H-H ) 7.3
Hz, CH3), 1.27 (4H, m, CH2CH3), 1.89 (2H, m, J H-H ) 5.6 Hz,
CH2CH2CH3), 2.14 (2H, m, J H-H ) 5.6 Hz, CH2CH2CH3), 2.51
(2H, m, J H-H ) 5.5 Hz, CH2N), 2.82 (2H, m, J H-H ) 5.3 Hz,
CH2N), 3.58 (1H, br s, HN), 7.02, 7.91 (15H, m, P(C6H5)3). 31P
{1H} NMR (109 MHz, C6D6): δ 44.3 (d, J Rh-P ) 153.3 Hz). IR
(KBr): νCO 1965.0 cm-1. FAB-MS: m/z 557.02. Anal. Calcd
1
led to the isolation of 2 (26.5 mg, 86%) as an orange solid. H
NMR (270 MHz, C6D6): δ 0.85 (3H, t, J H-H ) 6.9 Hz, CH3),
0.98 (4H, m, CH2CH2), 1.17 (4H, m, CH2CH2), 2.52 (2H, t, J H-H
) 5.2 Hz, CH2N), 2.69 (2H, s, H2N), 7.08, 7.96 (15H, m,
P(C6H5)3). 31P {1H} NMR (109 MHz, C6D6): δ 45.2 (d, J Rh-P
)
154.4 Hz). IR (KBr): νCO 1969.5 cm-1. FAB-MS: m/z 529.08.
Anal. Calcd for C25H30PONClRh (529.85): C, 56.67; H, 5.71;
N, 2.64. Found: C, 56.36; H, 5.74; N, 2.76.
Rh Cl(CO)(P P h 3)[NH2(C6H11)] (3). Reaction of cyclohexyl-
amine (4.81 µL, 4.17 mg, 0.084 mmol) and [Rh(CO)(Cl)(PPh3)]2
(36 mg, 0.042 mmol) using a procedure analogous to the
preparation of 1 led to the isolation of 3 (42.7 mg, 96%) as a
yellow microcrystalline solid. 1H NMR (270 MHz, C6D6): δ
0.90 (6H, m, CH2), 1.89 (4H, m, CH2), 2.61 (1H, m, CHN), 2.83
(2H, s, H2N), 7.05, 8.00 (15H, m, P(C6H5)3). 31P {1H} NMR
(109 MHz, C6D6): δ 44.5 (d, J Rh-P ) 154.6 Hz). IR (KBr): νCO
1968.9 cm-1
. FAB-MS: m/z 527.5. Anal. Calcd for C25H28-
PONClRh (527.83): C, 56.89; H, 5.35; N, 2.65. Found: C,
56.19; H, 5.61; N, 2.80.
Rh Cl(CO)(P P h 3)[NH2C(CH3)2CH2C(CH3)3] (4). Reaction
of tert-octylamine (7.5 µL, 6.02 mg, 0.047 mmol) and 1a (20
mg, 0.0233 mmol) using a procedure analogous to the prepara-
tion of 1 led to the isolation of 4 (23.9 mg, 88%) as a yellow/
orange solid. 1H NMR (270 MHz, C6D6): δ 0.82 (9H, s,
(CH3)3C), 1.03 (2H, s, CH2), 1.25 (6H, s, (CH3)2C), 3.17 (2H, s,
H2N), 7.04, 7.98 (15H, m, P(C6H5)3). 31P {1H} NMR (109 MHz,
for
C27H34PONClRh (557.9): C, 58.13; H, 6.14; N, 2.51.
Found: C, 57.92; H, 6.32; N, 2.38.
Rh Cl(CO)(P P h 3)[HN(CH2CH(CH3)2)2] (10). Reaction of
diisobutylamine (16.2 µL, 11.9 mg, 0.0926 mmol) and 1a (39.7
mg, 0.046 mmol) using a procedure analogous to the prepara-
tion of 6 led to the isolation of 10 (47.2 mg, 91%) as a pale
yellow solid. 1H NMR (270 MHz, C6D6): δ 0.89 (12H, d, J H-H
) 6.6 Hz, CH3), 1.59 (2H, m, J H-H ) 6.6 Hz, CH(CH3)2), 2.64
(2H, m, J H-H ) 7.9 Hz, CH2N), 2.92 (2H, m, J H-H ) 7.6 Hz,
CH2N), 3.84 (1H, br s, NH), 7.01, 7.90 (15H, m, P(C6H5)3). 31P
{1H} NMR (109 MHz, C6D6): δ 44.4 (d, J Rh-P ) 154.7 Hz). IR
(KBr): νCO 1968.0 cm-1. FAB-MS: m/z 556.93. Anal. Calcd
for C27H34PONClRh (556.93): C, 58.13; H, 5.42; N, 2.51.
Found: C, 57.95; H, 5.46; N, 2.53.
C6D6): δ 45.8 (d, J Rh-P ) 156.7 Hz). IR (KBr): νCO 1971.0 cm-1
FAB-MS: m/z 557.15. Anal. Calcd for 27H34PONClRh
.
C
(557.89): C, 58.13; H, 6.14; N, 2.51. Found: C, 57.82; H, 6.07;
N, 2.55.
Rh Cl(CO)(P P h 3)[HN(CH3)2] (5). A mixture of dimethyl-
amine (0.050 mL, 0.064 mmol) and 1a in THF (27.6 mg, 0.0322
mmol) was stirred at ambient temperature for 3 h, followed
by extraction of the product and drying the residue in vacuo.
Recrystallizing from THF/hexanes mixture led to the isolation
of 5 (28.6 mg, 94%) as a pale yellow solid. 1H NMR (270 MHz,
C6D6): δ 2.23 (6H, d, J H-H ) 6.3 Hz, CH3N), 3.10 (1H, br s,
NH), 7.01, 7.92 (15H, m, P(C6H5)3). 31P{1H} NMR (109 MHz,
Rh Cl(CO)(P P h 3)[HN(CH2C6H5)2] (11). Reaction of diben-
zylamine (8.97 µL, 9.21 mg, 0.0467 mmol) and 1a (20 mg, 0.023
mmol) using a procedure analogous to the preparation of 6
1
led to the isolation of 11 (26.2 mg, 90%) as a yellow solid. H

4974 Organometallics, Vol. 17, No. 23, 1998
Petrucci et al.
NMR (270 MHz, C6D6): δ 4.18 (4H, dd, J H-H ) 7.2 Hz, CH2N),
4.50 (1H, br s, NH), 7.01, 7.77 (15H, m, P(C6H5)3), 7.32 (5H,
MS: m/z 648.72. Anal. Calcd for C35H30PONClRh (649.96):
C, 64.68; H, 4.65; N, 2.16. Found: C, 64.82; H, 4.57; N, 2.25.
Rh Cl(CO)(P P h 3)[N(CH2CH3)3] (18). Reaction of triethyl-
amine (8.13 µL, 5.90 mg, 0.0582 mmol) and 1a (25 mg, 0.0291
mmol) using a procedure analogous to the preparation of 6
led to the isolation of 18 (27.5 mg, 89%) as an orange
microcrystalline solid. 1H NMR (270 MHz, C6D6): δ 1.36 (9H,
t, J H-H ) 7.2 Hz, CH3CH2), 2.66 (6H, q, J H-H ) 7.2 Hz,
CH3CH2), 7.04, 7.93 (15H, m, P(C6H5)3). 31P {1H} NMR (109
MHz, C6D6): δ 47.8 (d, J Rh-P ) 176.3 Hz). IR (KBr): νCO
m, C6H5). 31P {1H} NMR (109 MHz, C6D6): δ 46.0 (d, J Rh-P
)
156.9 Hz). IR (KBr): νCO 1955.9 cm-1. FAB-MS: m/z 625.07.
Anal. Calcd for C33H30PONClRh (625.94): C, 63.32; H, 4.83;
N, 2.24. Found: C, 63.76; H, 4.95; N, 2.21.
Rh Cl(CO)(P P h 3)[HN(C5H10)] (12). Reaction of piperidine
(9.14 µL, 7.87 mg, 0.085 mmol) and 1a (39.6 mg, 0.0462 mmol)
using a procedure analogous to the preparation of 6 led to the
isolation of 12 (45.1 mg, 95%) as a pale yellow solid. 1H NMR
(270 MHz, C6D6): δ 1.38 (6H, s, CH2), 2.66 (4H, s, CH2), 3.39
(1H, s, HN), 7.04, 7.95 (15H, m, P(C6H5)3). 31P {1H} NMR (109
MHz, C6D6): δ 46.2 (d, J Rh-P ) 149.9 Hz). IR (KBr): νCO
1971.0 cm-1. FAB-MS: m/z 530.13. Anal. Calcd for C25H30
-
PONClRh (529.85): C, 56.67; H, 5.71; N, 2.64. Found: C,
56.23; H, 5.75; N, 2.57.
1960.5.0 cm-1. FAB-MS: m/z 512.82. Anal. Calcd for C24H26
-
[Rh Cl4(CO)(P P h 3)]-(H2N(CH2CH3)2)+ (19). A solution of
6 (40 mg, 0.08 mmol) and carbon tetrachloride (36.8 mg, 23
µl, 0.24 mmol) in benzene was set to reflux for 48 h. A color
change from pale yellow to orange occurred within 1 h. Orange
crystals began to precipitate out of the red/orange solution.
The solution was decanted, and the orange crystals were
washed with hexanes and dried in vacuo: yield, 30.84 mg, 63%.
1H NMR (270 MHz, CDCl3): δ 1.33 (6H, t, J H-H ) 7.2 Hz, CH3-
CH2), 3.12 (4H, q, J H-H ) 6.6 Hz, CH3CH2), 7.37, 8.00 (15H,
m, P(C6H5)3), 7.88 (2H, br s, NH2). 31P {1H} NMR (109 MHz,
CDCl3): δ 27.9 (d, J Rh-P ) 102.3 Hz). IR (KBr): νCO 2103.7
PONClRh (513.81): C, 56.10; H, 5.10; N, 2.73. Found: C,
55.76; H, 5.18; N, 2.94.
Rh Cl(CO)(P P h 3)[NH(C4H8O)] (13). Reaction of morpho-
line (6.92 µL, 6.91 mg, 0.079 mmol) and 1a (34 mg, 0.0396
mmol) using a procedure analogous to the preparation of 6
led to the isolation of 13 (37.8 mg, 82%) as a pale yellow
powder. 1H NMR (270 MHz, C6D6): δ 2.84 (4H, t, J H-H ) 6.9
Hz, (CH2)2N), 2.96 (4H, t, J H-H ) 6.3 Hz, (CH2)2O), 3.46 (1H,
s, NH), 7.06, 7.92 (15H, m, P(C6H5)3). 31P {1H} NMR (109
MHz, C6D6): δ 46.4 (d, J Rh-P ) 152.1 Hz). IR (KBr): νCO
1962.0 cm-1. FAB-MS: m/z 515.45. Anal. Calcd for C23H24
-
cm-1
. (-)FAB-MS: m/z 609.96. Anal. Calcd for C23H27-
PONClRh (515.77): C, 53.56; H, 4.96; N, 2.72. Found: C,
53.25; H, 4.72; N, 2.64.
PONCl4Rh (609.17): C, 45.35; H, 4.47; N, 2.29. Found: C,
45.62; H, 4.57; N, 2.04.
Rh Cl(CO)(P P h 3)[HN(C5H9(NC5H10))] (14). Reaction of
4-piperidinopiperidine (15.3 mg, 0.091 mmol) and 1a (39
mg,0.046 mmol) using a procedure analogous to the prepara-
tion of 6 led to the isolation of 14 (52.1 mg, 86%) as an orange
solid. 1H NMR (270 MHz, C6D6): δ 0.87 (6H, t, J H-H ) 6.9
Hz, (CH2)3), 1.44 (4H, q, J H-H ) 5.3 Hz, CH2), 2.07 (4H, t, J H-H
) 5.6 Hz, CH2), 2.21 (1H, m, (CH)N), 3.51 (4H, t, J H-H ) 6.3
Hz, CH2NRh), 3.51 (1H, s, NH(C5H10)), 3.56 (1H, s, HNRh),
7.06, 7.95 (15H, m, P(C6H5)3). 31P {1H} NMR (109 MHz,
[Rh ClBr 3(CO)(P P h 3)]-(H2N(CH2CH3)2)+ (20). Carbon
tetrabromide (25.5 mg, 0.78 mmol) was added to a solution of
6 (12.8 mg, 0.026 mmol) in benzene-d6, resulting in an
immediate color change from pale yellow to bright red with
the evolution of a red precipitate. The reaction was complete
within 1 h, and crystal formation occurred within 14 h. The
clear red solution was decanted, and the solvent removed in
vacuo to result in a red microcrystalline product: yield, 17.3
mg, 86%. 1H NMR (270 MHz, CDCl3): δ 1.44 (6H, t, J H-H
)
C6D6): δ 46.1 (d, J Rh-P ) 149.8 Hz). IR (KBr): νCO 1957.0 cm-1
FAB-MS: m/z 596.88. Anal. Calcd for 29H36PON2ClRh
.
6.9 Hz, CH3CH2), 3.32 (4H, q, J H-H ) 7 Hz, CH3CH2), 7.39,
8.07 (15H, m, P(C6H5)3), 7.71 (2H, br s, NH2). 31P {1H} NMR
(109 MHz, CDCl3): δ 8.5 (d, J Rh-P ) 77.2 Hz). IR (KBr): νCO
C
(597.94): C, 58.25; H, 6.07; N, 4.69. Found: C, 57.93; H, 6.15;
N, 4.72.
2090 cm-1
. MALDI-TOF: 742.7. Anal. Calcd for C23H27-
PONClBr3Rh (742.52): C, 37.20; H, 3.66; N, 1.89. Found: C,
37.88; H, 3.53; N, 1.85.
Rh Cl(CO)(P P h 3)[HN(CH3)(CH2CH3)] (15). Reaction of
N-ethylmethylamine (0.01 mL, 6.89 mg, 0.116 mmol) and 1a
(50 mg, 0.0583 mmol) using a procedure analogous to the
preparation of 6 led to the isolation of 15 (54.2 mg, 95%) as a
[Rh ClI3(CO)(P P h 3)]-(H2N(CH2CH3)2)+ (21). Carbon tet-
raiodide (62.2 mg, 0.12 mmol) was added to a solution of 6 (20
mg, 0.04 mmol) in C6D6, resulting in the immediate formation
of a dark red precipitate. The reaction was complete after 15
min. The solid was filtered, washed with hexanes (5 mL), and
recrystallized from a chloroform/benzene solution: yield, 30.1
yellow solid. 1H NMR (270 MHz, C6D6): δ 1.21 (3H, t, J H-H
)
6.9 Hz, CH3), 3.37 (3H, d, J H-H ) 5.3 Hz, CH3N), 2.57 (2H, m,
J H-H ) 6.2 Hz, CH2N), 3.22 (1H, br s, NH), 7.03, 7.90 (15H,
m, P(C6H5)3). 31P {1H} NMR (109 MHz, C6D6): δ 45.1 (d, J Rh-P
) 162.4 Hz). IR (KBr): νCO 1956.3 cm-1. FAB-MS: m/z 486.9.
Anal. Calcd for C22H24PONClRh (487.8): C, 54.17; H, 4.96;
N, 2.87. Found: C, 54.56; H, 4.71; N, 2.70.
mg, 77.4%. 1H NMR (270 MHz, CDCl3): δ 1.16 (6H, t, J H-H
)
7.3 Hz, CH3CH2), 2.81 (4H, q, J H-H ) 5.9 Hz, CH3CH2), 6.94,
8.33 (15H, m, P(C6H5)3), 7.63 (2H, br s, NH2). 31P {1H} NMR
(109 MHz, CDCl3): δ -0.59 (d, J Rh-P ) 78.3 Hz). IR (KBr):
Rh Cl(CO)(P P h 3)[HN(CH3)(CH2C6H5)] (16). Reaction of
N-benzylmethylamine (10.5 µL, 9.89 mg, 0.0817 mmol) and
(1a ) (35 mg, 0.0408 mmol) using a procedure analogous to the
preparation of 6 led to the isolation of 16 (41 mg, 91%) as a
yellow solid. 1H NMR (270 MHz, C6D6): δ 2.36 (3H, d, J H-H
) 5.6 Hz, CH3), 3.79 (1H, s, NH), 4.22 (2H, dd, J H-H ) 5.9 Hz,
CH2N), 7.03, 7.88 (15H, m, P(C6H5)3), 7.28, 7.71 (5H, m, (C6H5).
31P {1H} NMR (109 MHz, C6D6): δ 45.7 (d, J Rh-P ) 154.4 Hz).
IR (KBr): νCO 1965.0 cm-1. FAB-MS: m/z 549.08. Anal. Calcd
for C27H26PONClRh (549.842): C, 58.98; H, 4.77; N, 2.55.
Found: C, 58.62; H, 4.79; N, 2.48.
Rh Cl(CO)(P P h 3)[HN(CH3)(CH2(C14H9))] (17). Reaction
of 9-(methylaminemethyl)anthracene (19.2 mg, 0.0868 mmol)
and 1a (37.2 mg, 0.0434 mmol) using a procedure analogous
to the preparation of 6 led to the isolation of 17 (54.8 mg, 97%)
as an orange solid. 1H NMR (270 MHz, C6D6): δ 2.26 (3H,
dd, J H-H ) 5.6 Hz, CH3), 4.42 (1H, br s, NH), 5.54 (2H, dd,
J H-H ) 3.3 Hz, CH2), 7.31, 7.76, 8.15, 8.55 (9H, m, C14H9), 7.06,
7.95 (15H, m, P(C6H5)3). 31P {1H} NMR (109 MHz, C6D6): δ
46.2 (d, J Rh-P ) 152.3 Hz). IR (KBr): νCO 1966.0 cm-1. FAB-
νCO 2076 cm-1
.
(-)FAB-MS: m/z 973.45. Anal. Calcd for
C
23H27PONClI3Rh (883.52): C, 31.27; H, 3.08; N, 1.58; C23H27
-
PONI4Rh (975.03): C, 28.33; H, 2.79; N, 1.44. Found: C,
29.11; H, 2.84; N, 1.32.
Hyd r osila tion of 1-Hexen e Usin g 6. (a ) A 5.0 g (3.6 ×
10-2 mol) sample of phenyldimethylsilane and 5.1 g of 1-hexene
(6.1 × 10-2 mol) were added to 200 mg of RhCl(CO)(PPh3)-
(NEt2H) (3.99 × 10-4 mol) dissolved in 10 mL of benzene, and
the mixture were refluxed at 60 °C for 30 min. The uncon-
verted olefin was separated by distillation (1.98 g), and the
remaining liquid was distilled under vacuum to yield 6.84 g
of phenyldimethylhexylsilane (84.7%): 1H NMR (270 MHz,
C6D6): δ 0.24 (6H, s, SiCH3), 0.72 (2H, t, J H-H ) 8.6 Hz, SiCH2),
0.88 (3H, t, J H-H ) 6.3 Hz, CH3), 1.28 (8H, m, CH2), 7.21, 7.47
(5H, m, Si(C6H5)) ppm. IR (KBr/neat): ν 699, 728, 815.3,
1112.8, 1180.2, 1383.6, 2854.6, 2955.9, 3021, 3068.5 cm-1. GC-
MS (C6H6): 20.693 min., m/z 220. Turnover no.: (molprod
/
.
molcat) 77.9. Turnover efficiency: (molprod/molcat/h) 155.8 h-1
(b) A 5.0 g (1.92 × 10-2 mol) sample of triphenylsilane and

Rh(I) Mixed CO/ Phosphine/ Amine Complexes
Organometallics, Vol. 17, No. 23, 1998 4975
5.0 g of 1-hexene (5.95 × 10-2 mol) were added to 200 mg of
RhCl(CO)(PPh3)(NEt2H) (3.99 × 10-4 mol) dissolved in 10 mL
of benzene, and the mixture was refluxed at 60 °C for 30 min.
Excess 1-hexene was separated by distillation (2.5 g). The
product was distilled under vacuum to yield 5.95 g of tri-
phenylhexylsilane (89%): 1H NMR (270 MHz, C6D6): δ 0.84
(3H, t, J H-H ) 6.3 Hz, CH3), 1.14-1.39 (8H, m, CH2), 1.54 (2H,
m, J Si-H ) 9.88, CH2Si), 7.15, 7.59 (15H, m, Si(C6H5)3) ppm.
IR (KBr/neat): ν 699, 731, 804, 998, 1113, 1428, 1588, 2856,
2924, 3020, 3049, 3068 cm-1. GC-MS (C6H6): 22.158 min.,
m/z 344. Turnover no.: (molprod/molcat) 43.3. Turnover ef-
Uiso, were adjusted to a 20% higher value than the bonded
carbon or nitrogen atom. The cyclohexylamine group is
disordered over two orientations with occupancies of 0.70 and
0.30, respectively. The minor geometry was restrained to be
similar to that of the major orientation. For atoms closer than
0.5 Å, the thermal parameters were restrained to be similar.
Major orientation is numbered N1 and C11-C16, and minor
orientation is denoted as N2 and C61-C66.
X-ray data for 6 were collected on
a Rigaku AFC6-S
diffractometer. Cell constants were obtained from 24 reflec-
tions with 32° < 2θ < 40°. Data reduction was done using
the NRCVAX package.17 Structure was solved by a direct
method using SHELXS-86 and was refined using SHELXL-
93.16a,b All atoms except hydrogen were refined anisotropically.
Hydrogen atoms were introduced at idealized geometries.
Hydrogen atoms on the methyl groups were located at the
position of maximum electron density, and a common isotropic
thermal parameter was refined for each methyl group.
ficiency: (molprod/molcat/h) 86.5 h-1
.
P olym er iza tion of Styr en e Usin g [Rh (Cl)(CO)(P P h 3)-
(HNEt2] (6). A 25 mg sample of 6 (0.05 mmol) was dissolved
in 5 mL of benzene. Styrene (5 mL, 0.0435 mol) was added
via syringe followed by the addition of CCl4 (3 mL, 0.0311 mol).
The mixture was allowed to reflux for 14 h at 60 °C. The
solvent was removed in vacuo, resulting in a viscous orange
residue. Polystyrene was recrystallized from chloroform/
methanol, resulting in a white solid: yield, 2.105 g, 91%. 1H
NMR (270 MHz, CDCl3): δ 1.33 (2H, d, CH2), 1.85 (1H, s, Ar-
CH), 6.57, 7.07 (5H, m, C6H5). 13C {1H} NMR (270 MHz,
CDCl3): δ 40.61 (d, CHCH2), 127.9 (d, C5H5-C), 145.5 (m,
C5H5-C). IR (KBr): ν 3024, 2921, 1600, 1492, 1451, 1028, 906,
Small yellow crystals of 19 were mounted on a glass rod
and examined on a Rigaku AFC6-S diffractometer using Mo
KR radiation. Data were collected in ω scan mode on the
reduced cell, and crystallographic data are collected in Table
5. The cell was transformed to monoclinic C2/c after data
collection. Data reduction and absorption corrections were
done with TEXSAN.19 Structure refinement was performed
using SHELXL-96.16c All non-hydrogen atoms are anisotropic,
and hydrogen atoms are isotropic. Hydrogen atoms were
constrained to the parent site using a riding model; SHELXL-
9616c defaults, C-H 0.93-0.98, N-H 0.86 Å. The isotropic
factors, Uiso, were adjusted to a 50% higher value of the parent
site (methyl) and 20% higher for the others. A final verifica-
tion for possible missed solvent areas was performed using the
VOID routine of the PLATON program.18
758, 699, 538 cm-1
chain; wt average 6076 g/mol; polydispersity 2.08; turnover
rate 56.8 h-1
. GCP (CHCl3): no. average 2921 units/
.
P olym er iza tion of Meth yl Meth a cr yla te Usin g [Rh -
(Cl)(CO)(P P h 3)(HNEt2] (6). Poly(methyl methacrylate) was
prepared and isolated as was polystyrene using 6 (25 mg, 0.05
mmol), methyl methacrylate (5 mL, 0.047 mol), and CCl4 (3
mL, 0.031 mol) and refluxing the mixture for 14 h at 60 °C:
yield, 3.31 g, 89.7%. 1H NMR (270 MHz, CDCl3): δ 0.73 (3H,
s, CH3), 1.70 (2H, s, CH2), 3.49 (3H, s, O-CH3). 13C {1H} NMR
(270 MHz, CDCl3): δ 16.47 (m, CH3), 18.71 (m, CH2), 44.5 (s,
O-CH3), 51.78 (m, -CH2C(COOCH3), 177.82 (m, COOCH3).
A red crystal of 20 mounted on a glass fiber was examined
by a P4 Siemens diffractometer equipped with a Siemens
SMART 1K charge-coupled device (CCD) area detector using
graphite-monochromatic Mo KR radiation. Data reduction
processing, absorption correction, and structure solution and
refinement were carried out as described for compound 3.
IR (KBr): ν 2950, 1733, 1456, 1241, 1148, 988, 841, 750 cm-1
GCP (CHCl3): no. average 65 545 units/chain; wt average:
93 814 g/mol; polydispersity 1.43.; turnover rate 76.2 h-1
.
.
X-r a y Diffr a ction Stu d y. X-ray-quality crystals of 3 and
6 were grown from a mixture of benzene/hexanes by the slow
evaporation of the solvent. The crystals were cut from the
grown needles, mounted on a glass fiber, and transferred to
the diffractometer. All of the samples were stable in air.
Crystallographic data are summarized in Table 2. X-ray data
for 3 were collected on a P4 diffractometer equipped with a
Siemens SMART 1K charge-coupled device (CCD) area detec-
tor. Processing was carried out using the program SAINT,15a
which applied Lorenz and polarization corrections to three-
dimensionally integrated diffraction spots. The program
SADABS15b was utilized for the scaling of the diffraction data,
the decay correction, and an empirical absorption correction
based on redundant reflections. The structure was solved by
direct method using SHELXS-8616a and was refined using
SHELXL-93.16b Hydrogen atoms were calculated at idealized
positions using a riding model with different C-H distances
for the type of hydrogen. The isotropic displacement factors,
Ack n ow led gm en t. Financial support was gener-
ously provided by NSERC of Canada and FCAR of
Quebec. We also wish to thank Dr. J im Britten of
McMaster University (Canada) for the use of his dif-
fractometer with CCD detector for data collection of
compound 3 and Dr. Corinne Bensimon of Ottawa
University for data collection of compound 20. M.G.L.P.
thanks NSERC (Canada) and FCAR of Quebec (Canada)
for a postgraduate scholarship.
Su p p or tin g In for m a tion Ava ila ble: Tables of experi-
mental parameters, atomic coordinates and equivalent isotro-
pic displacement parameters, bond lengths and angles, torsion
angles, hydrogen coordinates, anisotropic parameters, least-
squares planes in crystal coordinates and deviations (64
pages). Ordering information is given on any current masthead
page.
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OM980419M
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(19) TEXSAN; Molecular Structure Corp.: The Woodlands, 1985.