Rhodium(I) acetylacetonato complexes with functionalized phosphines

Article abstract of DOI:10.1016/S0022-328X(98)00842-0

Rhodium(I) complexes [Rh(acac)(CO)(PR₃)] with 1,3,5-triaza-7-phosphatricyclo[3.3.1.1^3,7]decane (tpa), tris(2-cyanoethyl)phosphine (cyep), tris(3-sodium sulfonatophenyl)phosphine (tppts), tris(o-methoxyphenyl)phosphine (ompp), tris(p-methoxyphenyl)phosphine (pmpp), tris(2,4,6-trimethoxyphenyl)phosphine (tmpp), PPh₂(pyl), PPh(pyl)₂ and P(pyl)₃ (pyl=2-pyridyl) have been synthesized and characterized with ¹H- and ³¹P-NMR and IR spectra. The measured ³¹P coordination chemical shifts, Δδ³¹P{¹H}, correlate well with ν(CO). Differences in ¹H chemical shifts of methyl groups of acac ligand, Δδ_Me, depend both on steric and electronic properties of phosphine ligand. Thus Δδ_Me increases with decrease of Δδ³¹P{¹H} and increases with increase of the cone angle of phosphine. Catalytic activity of complexes with tpa, cyep and tppts has been investigated. They are efficient catalysts for hydrogenation of C=C and C=O bonds, isomerization of alkenes and hydroformylation of alkenes. The mechanism of isomerization of allyl alcohol to propanal has been elucidated.

Full text of DOI:10.1016/S0022-328X(98)00842-0

Journal of Organometallic Chemistry 570 (1998) 63–69
Rhodium(I) acetylacetonato complexes with functionalized phosphines
Florian P. Pruchnik *, Piotr Smolen´ski, Katarzyna Wajda-Hermanowicz
*
*
Faculty of Chemistry, Uni6ersity of Wroclaw, Joliot-Curie 14, 50-383 Wroclaw, Poland
Received 17 April 1998
Abstract
Rhodium(I) complexes [Rh(acac)(CO)(PR3)] with 1,3,5-triaza-7-phosphatricyclo[3.3.1.13,7]decane (tpa), tris(2-cya-
noethyl)phosphine (cyep), tris(3-sodium sulfonatophenyl)phosphine (tppts), tris(o-methoxyphenyl)phosphine (ompp), tris(p-
methoxyphenyl)phosphine (pmpp), tris(2,4,6-trimethoxyphenyl)phosphine (tmpp), PPh2(pyl), PPh(pyl)2 and P(pyl)3
1
(pyl=2-pyridyl) have been synthesized and characterized with H- and 31P-NMR and IR spectra. The measured 31P coordination
1
chemical shifts, Dl31P{1H}, correlate well with w(CO). Differences in H chemical shifts of methyl groups of acac ligand, DlMe
,
depend both on steric and electronic properties of phosphine ligand. Thus DlMe increases with decrease of Dl31P{1H} and
increases with increase of the cone angle of phosphine. Catalytic activity of complexes with tpa, cyep and tppts has been
investigated. They are efficient catalysts for hydrogenation of CꢀC and CꢀO bonds, isomerization of alkenes and hydroformyla-
tion of alkenes. The mechanism of isomerization of allyl alcohol to propanal has been elucidated. © 1998 Elsevier Science S.A.
All rights reserved.
Keywords: Rhodium(I) complexes; Acetylacetonate complexes; Water soluble phosphines; Homogeneous catalysis; Hydrogena-
tion; Hydroformylation
1. Introduction
–PR3+or OH groups into phosphine ligands [1–11].
Most investigations of metal phosphine complexes in-
volve the sulfonated arylphosphine ligands. Compara-
tively little work has been carried out on hydrophilic
trialkylphosphines. Interesting ligands are 1,3,5-triaza-
7-phosphatricyclo[3.3.1.13,7]decane (tpa) [10,12–18]
(Fig. 1), tris(2-cyanoethyl)phosphine (cyep). The cone
angle is 102° for the first phosphine [12,13,17,18] and
132° for the second [10]. Thus structure and reactivity
of complexes with these ligands should depend mainly
on their electronic properties. We describe herein rhodi-
um(I) complexes with 1,3,5-triaza-7-phosphatricy-
clo[3.3.1.13,7]decane (tpa), tris(2-cyanoethyl)phosphine
(cyep) and tris(3-sodium sulfonatophenyl)phosphine
(tppts) as well as with methoxyphenylphosphines and
2-pyridylphosphines. Catalytic properties of complexes
with tpa, cyep and tppts in one and two-phase systems
are also described.
Complexes of transition metals with functionalized
phosphines are thoroughly investigated because of their
interesting catalytic activity. Complexes with water sol-
uble phosphines are especially intensely studied. The
basic problem of homogeneously catalyzed processes is
the separation of the product from the solvent and the
catalyst. Water-soluble catalysts combine the advan-
tages of homogeneous and heterogeneous catalysis,
simple separation of the product from the catalyst and
high activity and selectivity [1–5]. Water solubilization
of known coordination and organometallic catalysts is
performed by incorporating highly polar functional
groups such as –SO3H, –COOH, –NH2, –NR3+,
* Corresponding author. Fax: +48 71204232; e-mail: pruch-
nik@wchuwr.chem.uni.wroc.pl
0022-328X/98/$ - see front matter © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00842-0

64
F.P. Pruchnik et al. / Journal of Organometallic Chemistry 570 (1998) 63–69
2. Experimental details
and then concentrated to ca. 4 cm3. After addition of
diethyl ether (2 cm3), the yellow product was filtered
off, washed with cold methanol and diethyl ether and
dried in vacuo (yield 0.234 g, 76%). Anal. Calc. for
C24H27Na3PO16RhS3: C, 33.10; H, 3.10. Found: C,
32.97; H, 2.96.1H-NMR (CD3OD, r.t.); l(ppm):
2.1. Synthesis and catalytic reactions
All manipulation were carried out under inert atmo-
sphere using standard Schlenk technique. Catalytic re-
actions under high pressure were carried out in
autoclaves (Berghof) and at atmospheric pressure in
glass vessels at constant volume. The autoclaves and
glass vessels were first filled with nitrogen and then with
solvent, reactants and catalyst. The reactors were subse-
quently filled with H2+CO, or H2 with several evacua-
tion/refill cycles. RhCl3 ·3H2O (Aldrich), cyep (Strem),
ompp (ABCR), pmpp (ABCR) and tmpp (Aldrich)
were used as received. Tpa [14], tppts [15],
Rh(acac)(CO)2 [19], [Rh(acac)(CO)(PPh2pyl)] [22],
[Rh(acac)(CO)(PPhpyl2)] [22], [Rh(acac)(CO)(Ppyl3)]
[22], were prepared as reported in the literature.
3
C6H4SO3− –H2, 8.365 (d, 3H, J(PH2)=11.5 Hz); H4,
7.944 (dq, 3H, 4J(H2H4)=4J(H4H6=5J(PH4)=1.5
3
Hz); H6, 7.631 (t, 3H, J(PH6=10.4 Hz); H5, 7.508 (dt,
3
3H, J(H5H6)=3J(H4H5)=7.7 Hz); CH, 5.60 (s, 1H);
CH3, 2.03 (s, 3H); CH3, 1.67 (s, 3H); 31P{1H}-NMR in
CD3OD: l 51.5 ppm, d, 1J(RhP)=178.0 Hz. IR:
w(CO)=1980 cm−1
2.5. Synthesis of [Rh(acac)(CO)(cyep)] (3)
A mixture of cyep (0.0606 g, 0.314 mmol) and
Rh(acac)(CO)2 (0.0810 g, 0.314 mmol) in acetone (5
cm3) was stirred at r.t. for 0.5 h. The yellow solution
was evaporated to dryness and the yellow compound
was recrystallized from methanol. The product was
washed with cold methanol and dried in vacuo (yield
0.1011 g, 76%). Anal. Calc. for C15H19N3PO3Rh: C,
42.55; H, 4.49; N, 9.92; P, 7.32. Found: C, 42.09; H,
4.32; N, 9.71; P, 7.26. 1H-NMR (CD3OD, r.t.): l
(ppm): CH, 5.60 (s, 1H); PCH2 2.89(m, 6H), CH2CN
2.37 (m, 6H); CH3, 2.06 (s, 3H); CH3, 1.97 (s, 3H);
31P{1H}-NMR: l 37.5 ppm, d, 1J(PRh)=171.2 Hz. IR:
2.2. Physical measurement
IR spectra (KBr pellets and nujol mulls) were
recorded on a Bruker IFS113v, NMR on a Bruker 300
AMX. Chromatographic measurements were carried
out on a HP5990 chromatograph using FID, TCD and
MS detectors. Elemental analyses were performed on a
Perkin Elmer 2400 CHN analyzer.
w(CO)=1968 cm−1, w(CN)=2244 cm−1
.
2.3. Synthesis of [Rh(acac)(CO)(tpa)] (1)
2.6. Synthesis of [Rh(acac)(CO)P(2-MeOC6H4)3] (4)
A mixture of tpa (0.0561 g, 0.357 mmol) and
Rh(acac)(CO)2 (0.0922 g, 0.357 mmol) in ethanol (5
cm3) was refluxed for ca. 3 h. The yellow product was
filtered off, washed with cold ethanol and dried in
vacuo (yield 0.089 g, 65%). Anal. Calc. for
C12H19N3PO3Rh: C, 37.23; H, 4.95; N, 10.85.. Found:
To a hot Rh(acac)(CO)2 (0.0750 g, 0.291 mmol)
solution in hexane (5 cm3) P(2-MeOC6H4)3 (0.103 g,
0291 mmol) in hexane (5 cm3) was added. The mixture
was refluxed for ca. 3 h. The yellow product was filtered
off, washed with hexane and dried in vacuo. (yield
0.1130 g, 66%). Anal. Calc. for C27H28O6PRh: C, 55.11;
1
C, 36.70; H, 4.57; N, 10.65. H-NMR (CD3OD, r.t.):
l(ppm) CH, 5.60 (s, 1H); NCH2N, 4.60 (s, 6H);
PCH2N, 4.27 (s, 6H); CH3, 1.97 (s, 6H); 31P{1H}-NMR:
l −25,5 d, J(RhP)=172.4 Hz. IR: w(CO)=1958
1
H, 5.82;. Found: C, 55.61; H, 5.77. H-NMR (CDCl3,
r.t.):
l
(ppm): C6H4OCH3–H6, 7.66 (dd, 3H,
3
3J(H6H5)=7.7Hz, J(PH6)=12.8 Hz); H4, 7.35 (t, 3H,
cm−1
.
3J(H5H6,4)=7.7 Hz); H5, 6.89 (t, 3H, J(H4H5,3)=7.7
3
Hz); H3, 6.79 (dd, 3H, J(H3H4)=8.1 Hz, J(PH3)=
4.5 Hz); CH, 5.28 (s, 1H), OCH3, 3.51 (s, 9H); CH3,
2.03 (s, 3H), CH3, 1.43 (s, 3H); 31P{1H}-NMR (CDCl3):
3
4
2.4. Synthesis of [Rh(acac)(CO)(tppts)] ·4H2O (2)
A mixture of tppts (0.2201 g, 0.388 mmol) and
Rh(acac)(CO)2 (0.1000 g, 0.388 mmol) in methanol (8
cm3) was stirred at room temperature (r.t.) for ca. 1 h
1
l 33.9 ppm, d, J(PRh)=181.3 Hz. IR: w(CO)=1963
cm−1
.
2.7. Synthesis of [Rh(acac)(CO)P(4-MeOC6H4)3] (5)
To a hot Rh(acac)(CO)2 (0.0750 g, 0.291 mmol)
solution in hexane (5 cm3) P(4-MeOC6H4)3 (0.103 g,
0291 mmol) in hexane (5 cm3) was added. The mixture
was refluxed for ca. 3 h. The yellow product was filtered
off, washed with hexane and dried in vacuo. (yield
0.1260 g, 74%). Anal. Calc. for C27H28O6PRh: C, 55.11;
Fig. 1. Tpa.

F.P. Pruchnik et al. / Journal of Organometallic Chemistry 570 (1998) 63–69
65
Table 1
31P{1H}-NMR and IR spectra of acetylacetonato rhodium(I) complexes
Compound
31P{1H}-NMR l (ppm)
(1JRhP (Hz))
Dl31P{1H}
Dl CH3(acac) 1H-
NMR (ppm)
Phosphine cone an- IR w(CO),
gle U (°)
Reference
(cm−1
)
-NMR (ppm)
1
2
3
−25.5 d (172.4)b
50.8 d (178.0)b
37.5 d (171.2)b
72.8
54.3
67.8
0
0.36
0.09
1958
1980
1968
2244a
1963
1976
1944
1981
1981
1975
1975
1946
1962
1976
1976
1986
1980
4
5
6
7
8
9
10
11
12
13
14
15
33.9 d (181.3)c
43.5 d (175.6)c
−5.03 d (186.9)d
49.1 d (179.7)c
52.7 d (180.2)c
56.6 d (177.0)c
61.1 d (174.7)c
58.9 d (182.1)c
69.2 d (166)c
73.2
64.3
61.3
54,6
55.9
58.5
61.5
47.6
49.2
0.60
0.44
0.50
0.49
0.57
0.46
0.43
[21]
[23]
[24]
[27]
[27]
[27]
[27]
[10]
[20]
[10]
[25]
[25]
[26]
0.18
0.46
0.42
0.52
0.46
16
tpa
tppts
cyep
−98.3b
−3.5b
−30.3b
−39.3c
−10.8c
−66.3e
−5.5c
−3.2c
−1.9c
−0.4c
11.3c
102
145
132
200
145
184
145
145
145
145
170
160
161
165
145
145
ompp
pmpp
tmpp
PPh3
PPh2pyl
Pphpyl2
Ppyl3
PCy3
P(Pri)3
PPh2(2-tol)
P(3-tol)3
P(4-CF3C6H4)3
P(4-FC6H4)3
([23]b)
([23]b)
19.3
−5.3f
[29]
7, Rh(acac)(CO)(PPh3); 8, Rh(acac)(CO)(PPh2pyl); 9, Rh(acac)(CO)(PPhpyl2); 10, Rh(acac)(CO)(Ppyl3); pyl, 2-pyridyl; 11, Rh(acac)(CO)(PCy3);
12, Rh(acac)(CO)(PPr3i ); 13, Rh(acac)(CO)(PPh2(2-tol)); 14, Rh(acac)(CO)(P(3-tol)3); 15, Rh(acac)(CO)(P(4-CF3C6H4)3); 16, Rh(acac)(CO)(P(4-
FC6H4)3).
a w(CN), b Recorded as a CD3OD solution. c Recorded as a CDCl3 solution. d Recorded as a toluene-d8 solution. e Recorded as a CD3CN solution.
f Recorded as a CD2Cl2 solution.
1
H, 5.82;. Found: C, 54.78; H, 5.06; H-NMR (CDCl3,
Anal. Calc. for C33H40O12PRh: C, 51.98; H, 5.29;.
1
r.t.):
l
(ppm), C6H4OCH3–H2,6
,
7.54 (dd, 6H,
Found: C, 51.09; H, 5.17; H-NMR (benzene d6, r.t.): l
3J(H2,6H3,5)=8,5 Hz, J(PH2,6)=10.6 Hz); H3,5, 6.87
(ppm), C6H2(OCH3)3–H3,5, 6.15 (d, 2H, J(PH3,5)=3.5
3
4
(dd, 6H, J(PH3,5)=2.1 Hz); CH, 5.40(s, 1H), OCH3,
Hz); H3,5, 6.02 (d, 4H, J(PH3,5)=2.5 Hz); CH, 5.18(s,
4
4
3.82 (s, 9H); CH3, 2.06 (s, 3H), CH3, 1.62 (s, 3H);
1H), OCH3, 3.40, 3.34, 3.29 (s, 27H); CH3, 2.90 (s, br,
31P{1H}-NMR (CDCl3): l 43.5 ppm, d, 1J(PRh)=
3H); CH3, 1.59 (s, br, 3H); 31P{1H}-NMR (toluene d8):
175.6 Hz. IR: w(CO)=1976 cm−1
.
l −5.03 ppm, d, J(PRh)=186.9 Hz. IR: w(CO)=
1
1944 cm−1
.
2.8. Synthesis of [Rh(acac)(CO)P(2,4,6-MeOC6H4)3] (6)
A hot solution of Rh(acac)(CO)2 (0.0750 g, 0.291
mmol) in hexane (5 cm3) was added dropwise to a
suspension of P(2,4,6-MeOC6H4)3 (0.1548 g, 0291
mmol) in hexane (10 cm3). The mixture was refluxed for
ca. 3 h. The orange product was filtered off, washed
with hexane and dried in vacuo (yield 0.1770 g, 80%).
3. Results and discussion
3.1. Syntheses
Treatment of Rh(acac)(CO)2 with stoichiometric
amounts of 1,3,5-triaza-7-phosphatricyclo[3.3.1.13,7]-

66
F.P. Pruchnik et al. / Journal of Organometallic Chemistry 570 (1998) 63–69
Fig. 2. The dependence of the coordination chemical shift Dl(31P) on the wCO stretching frequency for [Rh(acac)(CO)(PR3)] complexes. R=0.95;
S.D.=2.48. Points for 6, 11 and 12 are not included in the regression line.
Fig. 3. The dependence of the cone angle on the DlCH3 1H-NMR for [Rh(acac)(CO)(PR3)] complexes. R=0.64; S.D.=17.81.
decane (tpa), tris(2-cyanoethyl)phosphine (cyep) and
tris(3-sodium sulfonatophenyl)phosphine (tppts) in
methanol, ethanol or acetone at stoichiometric ratios
afforded the complexes [Rh(acac)(CO)(tpa)] 1,
[Rh(acac)(CO)(tppts)]·4H2O 2, and [Rh(acac)(CO)-
(cyep)] 3. Coordination compounds with ompp, pmpp
and tmpp can be prepared in nonpolar solvents. Com-
dichloromethane, chloroform, acetone, arenes, spar-
ingly soluble in alkanes and insoluble in water. How-
ever, complexes with pyridylphosphine are soluble
in water in the presence of strong acids owing to
protonation of nitrogen atoms of 2-pyridyl rings. The
complexes are air stable in solid state, however in
solutions they are oxidized in air with the loss of a
carbonyl ligand and formation of appropriate phos-
phine oxide. All complexes have been characterized by
plexes 1, 2,
3 are soluble in water, methanol,
dichloromethane and other polar solvents, slightly solu-
ble in chloroform and higher alcohols and insoluble in
nonpolar solvents and complexes 4–10 are soluble in
1
means of elemental analysis, IR and H- and 31P-NMR
spectra.

F.P. Pruchnik et al. / Journal of Organometallic Chemistry 570 (1998) 63–69
67
Fig. 4. The dependence of the coordination chemical shift Dl(31P) on the DlCH3 1H-NMR for [Rh(acac)(CO)(PR3)] complexes. R=0.81;
S.D.=3.97. The point for 4 is not included in the regression line.
The 31P{1H}-NMR and w(CO) stretching vibration
for Rh(acac)(CO)(PR3) complexes are given in Table 1.
The 31P coordination chemical shift Dl(31P) as well as
1J(RhP) are typical for Rh(acac)(CO)(PR3) complexes.
The w(CO) frequencies for investigated complexes
change in the range 1944–1981 cm−1 and depend on
|-donor and y-acceptor properties of phosphines be-
cause PR3 and CO interact with the same rhodium dy
orbital. Electron density donated by phosphines is then
back-donated from the central atom into the y* orbital
of the CO ligand and this leads to the decrease of the
w(CO) frequency. Low w(CO) frequencies for complexes
1 and 6 are indicative of relatively strong |-donor and
rather weak y-acceptor properties of tpa and ompp,
while |-donor and y-acceptor abilities of tppts, pmpp
and pyridylphsphines are similar to those of PPh3, cyep
shows intermediate properties. On the other hand the
more strength of the metal–phosphine bond the larger
Dl31P{1H}=lcomplex−lphosphine. Thus a relationship
between Dl31P and the carbonyl stretching frequency
should be observed. Data given in Table 1 and pre-
sented in Fig. 2 confirm this conclusion. It is interesting
that this dependence is fulfilled both for alkyl- and
arylphosphines, except of phosphines with cone angle
considerably greater than that for PPh3 (145°).
electronic properties of PR3 and CO ligands. The DlMe
values should depend to a lesser extent on bulkiness of
phosphine ligands because their steric interaction with
the CH3 group of acac is rather weak. Therefore the
correlation between DlMe and Dl31P is better than the
dependence of DlMe on U cone angle (Fig. 3 and Fig.
4). Similar dependeces of reactivity of phosphine com-
plexes on the electronic and steric properties of PR3
ligands have also been found [27,28,30], e.g. enthalpies
of carbonyl ligand substitution by PR3 in
Rh(acac)(CO)2 show a proportional dependence on the
carbonyl stretching frequencies of Rh(acac)(CO)(PR3)
complexes [27]. In the case of complex 1, there is only
one signal of methyl groups. This suggests that trans
influences for tpa and CO are comparable and steric
influences of the compact tpa ligand is negligible and
therefore acetylacetonato ligand is symmetrically coor-
1
dinated with rhodium. The H-NMR spectrum of 1 is
simple, PCH2N and NCH2N methylene groups give
singlets showing that axial and equatorial protons in
this complex, like in free tpa, are equivalent. In all
complexes deshielding effect of the central atom was
observed. In complex 2, H2 is the most effectively
deshielded; its chemical shift (8.365 ppm) is higher than
that in OP(C6H4SO3Na-3)3 (8.25 ppm).
Complexes 1–3 in aqueous solutions are effective
catalysts for hydrogenation of alkenes and allyl alcohol
under mild conditions. The initial TOF values are much
higher for alkenes than for CH2ꢀCHCH2OH. This sug-
gests that CꢀC bond of allyl alcohol is relatively
strongly coordinated with the rhodium atom and there-
fore transfer of the hydrido ligand to the substrate is
1
In the H-NMR spectra of Rh(acac)(CO)(PR3) com-
plexes, two signals of CH3 groups of 2,4-pentanodion-
ato ligand are observed since one oxygen atom occupies
trans coordination site to the phosphine molecule and
other trans position to the carbonyl ligand. The differ-
ences between chemical shifts of the methyl groups,
DlMe, should chiefly depend on trans influence, thus, on

68
F.P. Pruchnik et al. / Journal of Organometallic Chemistry 570 (1998) 63–69
Scheme 1. Mechanism of isomerisation of allyl alcohol.
Table 2
Hydrogenation and hydroformylation of alkenes and allyl alcohol in the presence of [Rh(acac)(CO)(PR3)] complexes 1–3
Catalyst
Substrate
Products (%)
Initial rate of reaction
(mol·(h·mol Rh)−1
)
1
1
1-Hexene, Ha2
1-Cyclohexene,
H2a
n-Hexane
Cyclohexane
143
92
1
1
Allyl alcohol,
n-Propanol(90), propanal(10)
26
Ha2,c
1-Hexene, H2,
COb
n-Heptanal(34.1), i-heptanal(13.6), 2-hexene (11.0), 3-hexene (6.2)
61d
2
2
1-Hexene, Ha2
1-Cyclohexene,
H2a
n-Hexane
Cyclohexane
260
257
2
2
Allyl alcohol,
n-Propanol(99), propanal(1)
n-Heptanal(53), i-heptanal(47)
23.4
111d
Ha2,c
1-Hexene, H2,
COb
3
3
1-Hexene, Ha2
Allyl alcohol,
Ha2,c
n-Hexane
n-Propanol(95), propanal(5)
96
21.2
3
1-Hexene, H2,
n-Heptanal(53), i-heptanal(43), isomers of hexene(1.9), n-heptanoic acid(1.2), 109d
i-heptanoic acid(0.9)
b
CO
a Substrate 0.02 mol; catalyst 10−5 mol; 15 cm3 H2O; p(H2)=0.1 MPa; temperature 30°C. b Substrate 0.02 mol; catalyst 10−5 mol; 15 cm3 H2O;
p(H2)=p(CO)=3.0 MPa; temperature 60°C; 18 h. c One-phase system. d Average TOF.
slower than that in the case of 1-hexene. In the presence
of all complexes, allyl alcohol is partly isomerized to
propanal. Hydrogenation of CH2ꢀCHCH2OH in D2O
solution gives n-propanol, CH3CHDCHO and
molecule occurs because propanal containing deuterium
atoms in methyl group CDH2CDHCHO is not formed.
In the case of heterolytic splitting of dihydrogen, easy
isotopic exchange between H2 and deuterated solvent
should take place and propanal with deuterated methyl
group should be formed.
1
CH3CHDCH(OD)2. The H-NMR spectrum of the re-
action products shows a doublet of triplets at 0.88 ppm
3
3
with J(HH)=7.2 and J(HD)=1.1 Hz for the methyl
The yield of isomerization decreases in the order:
1\3\2, thus, the lower w(CO) the higher yield of
isomerization. This indicates also that the decrease of
stability of hydrido complexes is: tpa\cyep\tppts, it
confirms also the proposed mechanism of isomeriza-
tion. However, even for complex with tpa, hydrido
group of propanal and a quartet of doublets at 2.39
3
2
ppm with J(HH)=7.2 and J(HD)=1.3 Hz for the
CHD group apart from signals of n-propanol. Thus
isomerization is most likely catalyzed by hydrido
rhodium complexes, according to the mechanism given
in Scheme 1. Most probably homolytic splitting of H2
1
complexes have not been detected with H-NMR.

F.P. Pruchnik et al. / Journal of Organometallic Chemistry 570 (1998) 63–69
69
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The investigated complexes catalyze also hydro-
formylation of alkenes in aqueous solutions. The aver-
age values of TOF are relatively high (60–110),
however, selectivity of complexes without excess of
phosphine ligand is low. It is interesting that among the
products of hydroformylation of 1-hexene in the pres-
ence of complex 3, n-heptanoic and 2-methylhexanoic
acids were found. They are most likely formed owing to
the nucleophilic attack of water molecule on RC(O)–
Rh bond. Complexes 1, 2 and 3 are also catalysts for
isomerization of alkenes in dihydrogen atmosphere.
This indicates that isomerization, analogously as in the
case of isomerization of allyl alcohol, is catalyzed by
hydrido rhodium(III) complexes [RhH2(acac)L(PR3)].
During hydrogenation of 1-hexene substantial amounts
of 2-hexene and 3-hexene are formed (Table 2). Thus
rate of isomerization is comparable with the rate of
hydrogenation. The carbonyl ligand in all catalytic
reactions is transformed into formic acid which in the
case of complex 1, most likely, forms formates with tpa
owing to protonation of nitrogen atoms of phosphine.
*
*
Rusek, E. Galdecka, Z. Galdecki, Inorg. Chim. Acta 232 (1995)
*
*
207. (b) E. Galdecka, Z. Galdecki, K. Wajda-Hermanowicz, F.P.
Pruchnik, J. Chem. Crystallogr. 25 (1995) 717.
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Acknowledgements
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(1992) 2667.
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Chim. Acta 26 (1978) L35.
The authors are grateful to the Committee of Scien-
tific Research, KBN, for support of this work (grant
No. 3 T09A 092 10).
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