1
336
TELESHEV et al.
Catalytic activity of complexes асасRh(СО)L in the hydrogenation and isomerization of hept-1-ene (toluene, 70°С, РН2 1 atm,
-
3
–1
–1
[
Rh]=5×10 g-at l , [1-heptene] = 1 mol l , reaction time 100 min)
Catalytic properties
L in асасRh(СО)L
yield, %
–1
–1
α, mol Н
2
(g-at Rh ) min
heptane
20
trans-hept-2-ene cis-hept-2-ene
Oligo(hexamethylene diethylphosphoamidite)
Triethyl phosphite
0.41
0.42
0.57
35
19
21
14
10
11
21
Triphenylphosphine
29
organic solvents. Due to this property, the metal
polymer containing excess free P(III) atoms holds pro-
mise for application in catalytic reactions of carbon(II)
oxide. Such reactions, e.g., hydroformylation, require
the acacRh(CO)L–nL reaction system to contain a
buffer organic P(III) ligand nL for maintaining exis-
tence of active centers in the catalytic system [12].
Synthesis of preparing oligo(phosphoramidites)
(form B) (general procedure). To 0.01 mol of diol in
10 ml of dioxane, 0.01 mol of phosphorous triamide
was added, and the mixture was stirred at 20–45°С
(200–250 mm Hg) for 12–15 h. The solvent was then
removed by vacuum distillation (1 mm Hg) at 45°С.
31
Yield 85%. Р NMR spectrum (dioxane), δ
39.
, ppm: 147;
P
1
The immobilized metal complex of the асасRh(СО)L
type, where L is oligo(hexamethylene diethylphosphor-
amidite) was studies as a catalyst for hydrogenation of
hept-1-ene. The hydrogenation was carried out at 70°С in
toluene.
Oligo[acetylacetonatocarbonyl(hexamethylene
diethylphosphoramidite)rhodium(I)]. To 2.19 g
(0.01 mol) of oligo(hexamethylene diethylphos-
phoramidite) (form B) in 10 ml of dioxane, 0.86 g
(
0.0033 mol) of acetylacetonatodicarbonylrhodium(I)
According to the resulting data, oligo[acetyl-
acetonatocarbonyl(hexamethylene diethylphosphor-
amidite)] as a catalyst precursor offers no advantages over
rhodium complexes with trethyl phosphite or triphe-
nylphosphine ligands (see table). Note that the reaction
with the catalyst based on oligo(hexamethylene diethyl-
phosphoramidite) occurs in preference for isomerization to
trans-hept-2-ene, probably due to stereo-chemical features
of the carrier ligand (see table).
was added. The mixture was stirred at 20°С for 30 min
under argon. Precipitate formation was observed. The
solvent was removed by vacuum distillation, and the
residue was dried at 70–80°С (1 mm Hg). The product
is a solid friable light-yellow substance insoluble in
organic solvents. Decom. point 135–150°С. IR
–1 31
spectrum (КBr): ν(CO) 1989 cm . Р NMR spectrum
(
dioxane): δ 138.4 ppm. Found, %: С 45.81, 45.93; H
P
6
.37, 6.61; P 7.67, 7.94. С H NO PRh. Calculated,
1
6
28
3
Attempted additional activation of the rhodium
oligo(hexamethylene diethylphosphoramidite) complex
by treatment with molecular oxygen led to a sharp fall
of the hydrogenating activity of the system, which is
probably connected with oxidation of the oligomeric
phosphorus-containing ligand.
%: С 46.16; Н 6.78; Р 7.44.
Oligo[pentacarbonyl(hexamethylene diethylphos-
phoramidite)molybdenum(0)]. To 2.19 g (0.01 mol)
of oligo(hexamethylene diethylphosphoramidite) (form
B) in 10 ml of dioxane, 2.64 g (0.0033 mol) of hexa-
carbonylmolybdenum(0) was added. The mixture was
stirred under argon at 95°С for 2 h. The solvent was
then removed by distillation, and the residue was dried
in a vacuum at 70–80°С. The product is a solid friable
EXPERIMENTAL
31
The Р NMR spectra were registered on a Bruker
31
substance. Р NMR spectrum (dioxane): δ 164.3 ppm.
WP-80 instrument at 32.4 MHz, external reference
P
Found, %: С 47.19, 46.88; Н 6.98, 6.79; Р 8.57, 8.39.
8
5% Н РО . Thermal analysis was carried out on a
3 4
С H MoNO P. Calculated, %: С 47.37; Н 7.16; Р
Shimadzu DTG-50 instrument, accuracy 1%, sen-
15 27
2
–
1
8.14.
sitivity 0.005 mg, heating rate 20.0°C min , reference
an empty aluminum cell. The IR spectra were
registered on a Specord 75IR instrument from KBr
pellets.
Hydrogenation. The complex асасRh(СО)L,
×10 mol, was placed under argon to a reactor
–
5
5
maintained at 70°С and containing 10 ml of toluene.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 7 2008