Functionalized ether derivatives of HOCH2C(CH2PPh2)3 and related tripod ligands - Synthesis and coordination chemistry

Article abstract of DOI:10.1002/(sici)1099-0682(199810)1998:10<1407::aid-ejic1407>3.0.co;2-j

Neopentane-derived tripod ligands of the general type HOCH₂C(CH₂PPh₂)(CH₂Y)(CH ₂Z) (1; Y, Z = PPh₂, SR) are notoriously resistant to ether formation at their hydroxy group. Two routes have been found, which allow the transformation of 1 into ether functionalized tripod ligands ROCH₂C(CH₂PPh₂)(CH₂Y)(CH ₂Z) (Y = Z = PPh₂: 5, Y = Z = SR: 8). One of these strategies relies upon the ?3 coordination of 1 in 1·Mo(CO)₃ (2). By this way the donor groups are efficiently protected and the steric encumbrance of the CH₂OH group at the backbone of the ligands is greatly reduced by fixing three arms of the neopentane scaffolding to the metal center. After deprotonation, reaction with electrophiles will produce the corresponding ether derivatives ROCH₂C(CH₂PPh₂)(CH₂Z)₂ (3). Mesylation of 2 leads to MeSO₂OCH₂C(CH₂PPh ₂)3·Mo(CO)₃ (4), which reacts with alkoxides to produce 3 in a sequence of reversed polarity. Ligands 5 [ROCH₂C(CH₂PPh₂)₃] are liberated from 3 by UV irridation of their solutions in the presence of pyridine N-oxide. Direct etherification of 1 is also possible in some cases after deprotonation of 1 by KOfBu and subsequent reaction with an electrophile RX in the narrow temperature range between -10 and +20 °C. By this way, ω-methyl polyglycol ether functions are easily introduced resulting in H₃C(OC₂H₄)_nOCH₂C(CH ₂PPh₂)₃ (5g, h).

Full text of DOI:10.1002/(sici)1099-0682(199810)1998:10<1407::aid-ejic1407>3.0.co;2-j

FULL PAPER
Functionalized Ether Derivatives of HOCH2C(CH2PPh2)3 and Related Tripod
Ligands – Synthesis and Coordination ChemistryȠ
Peter Schober, Rainer Soltek, Gottfried Huttner*, Laszlo Zsolnai, and Katja Heinze
Anorganisch-Chemisches Institut der Universität Heidelberg,
Im Neuenheimer Feld 270, D-69120 Heidelberg, Germany
Fax: (internat.) ϩ 49(0)6221/545707
Received March 16, 1998
Keywords: Functionalized tripod ligands / Mixed donor set ligands / Solubilized tripod ligands / Molybdenum / Iron /
Neopentane-derived tripod ligands of the general type
HOCH2C(CH2PPh2)(CH2Y)(CH2Z) (1; Y, Z = PPh2, SR) are
notoriously resistant to ether formation at their hydroxy
group. Two routes have been found, which allow the
transformation of 1 into ether functionalized tripod ligands
ROCH2C(CH2PPh2)(CH2Y)(CH2Z) (Y = Z = PPh2: 5, Y = Z =
SR: 8). One of these strategies relies upon the η3 coordination
of 1 in 1·Mo(CO)3 (2). By this way the donor groups are
efficiently protected and the steric encumbrance of the
CH2OH group at the backbone of the ligands is greatly
reduced by fixing three arms of the neopentane scaffolding
to the metal center. After deprotonation, reaction with
electrophiles will produce the corresponding ether
derivatives ROCH2C(CH2PPh2)(CH2Z)2 (3). Mesylation of 2
leads to MeSO2OCH2C(CH2PPh2)3·Mo(CO)3 (4), which
reacts with alkoxides to produce 3 in a sequence of reversed
polarity. Ligands 5 [ROCH2C(CH2PPh2)3] are liberated from
3 by UV irridation of their solutions in the presence of
pyridine N-oxide. Direct etherification of 1 is also possible in
some cases after deprotonation of
1 by KOtBu and
subsequent reaction with an electrophile RX in the narrow
temperature range between –10 and +20 °C. By this way, ω-
methyl polyglycol ether functions are easily introduced
resulting in H3C(OC2H4)nOCH2C(CH2PPh2)3 (5g, h).
Introduction
As a consequence a well-thought-of strategy for design-
One of the properties of a ligand which has not been ing a particular class of ligands will from the very beginning
generally considered to be too important is its solubility in incorporate a functionality which may serve as a linker
different solvents and the herewith introduced solubility of group such as to allow for all the modifications eventually
its coordination compounds. On the other hand it has been needed. In a project concerned with the synthesis and appli-
shown how solubility properties may considerably improve cation of tripod ligands RCH2C(CH2X)(CH2Y)(CH2Z)
processes which rely on the catalytic activity of ligand-metal much work has been devoted to the problem of designing
templates, one of the examples of even technical importance
a
convergent strategy to introduce different donor
being the Rhone-Poulenc process.[1] In this case hydrophilic groups[8a][8b][8c][8d][8e][8f][8g][8h], even enantioselective pro-
phosphane ligands are the reason for the advance.[2] Many cedures have been worked out.[9a][9b][9c] The problem of in-
other catalytic processes do in principle allow for this kind troducing a linker group at the backbone has, however, not
of modification[3], given that the ligand can be appropri- yet been solved in a convergent way. Wherever syntheses of
ately modified. Modifying ligands to enhance and specify ligands modified in this sense had been reported, the modi-
solubility is thus of basic interest. Modifying ligands by at- fied groups were incorporated from the very beginning of
taching auxiliary groups, such as to allow the attachment the syntheses.[8k][8m] Even though with the synthesis of
of ligand-metal templates to a surface is another reason for HOCH2C(CH2X)(CH2Y)(CH2Z)[8k] the alcohol function
putting more weight to the question of an appropriate func- appears to naturally lend itself to further functionalization,
tionalizability of a ligand.[3] Homogeneous processes may the steric bulk of the neopentane system hitherto precluded
be transferred to heterogenous ones using this approach the scope of this reaction. Only silylation and esterifi-
combining the advantages of both homogeneous and het- cation[8k] leading to R3SiϪ and RCOOϪ derivatives had
erogeneous catalyses.[4] Modifying ligands such as to induce been found to work. And even with these reactions the pro-
a self-assembly type of order in the phases derived from tection of donor functions X, Y, Z like PR2 was found to
their coordination compounds is yet another point of inter- be necessary. The functionalizations thus introduced
est in this topic.[5] The rapid development of chemical sen- strongly limit the potential application of these ligands due
sors[6] as well as of non-linear optical materials[7] will to their sensitivity to hydrolysis. An ether functionality
further increase the demand for ligands which do not only would be far more superior. Despite continued efforts[8k][8l]
have the appropriate coordinative capabilities but do at the to achieve etherification of the hydroxymethyl group of
same time allow for easy-to-achieve modifications by ad- these neopentane-based ligands definitive solutions of this
ditional functionalities in order to imprint the specific problem have only now been found. We report here on
properties which are needed in each case to their coordi- methods which allow for this type of modification of tripod
nation compounds.
ligands and which are at the same time tolerant to a broad
Eur. J. Inorg. Chem. 1998, 1407Ϫ1415
WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1998
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1407

P. Schober, R. Soltek, G. Huttner, L. Zsol
FULL PAPER
range of functionalities in the auxiliary group as well as in ordinating all three donor groups to one metal center. This
the donor set of the ligands.
should protect the donor groups and should at the same
time reduce the steric crowding around the CH2OH group
at the neopentane framework with this steric crowding be-
ing the main reason for the reduced reactivity of neopen-
tane derivatives.[10] It is observed that the tricarbonylmo-
lybdenum fragment serves as an efficient template in this
sense. Tripod tricarbonylmolybdenum complexes are easily
accesible and remarkably stable.[8i][8k][8l] Thus, ligands 1 are
transformed into their Mo(CO)3 derivatives 2 (Scheme 1)
with excellent yields (Experimental Section).
Results and Discussion
Modification of Coordinated Ligands
There are two main reasons for the failure of the trans-
formation of the CH2OH group in HOCH2C(CH2X)-
(CH2Y)(CH2Z) into an ether function: one of them being
the sluggish reactivity of the neopentane system[10] and the
other one being inherent in the sensitivity of the donor
groups to electrophilic attack.[8k][8l] This second impedi-
ment may in part be overcome by appropriate protection of
the donor groups e.g. adduct formation of PR2 donors with
borane to give protected PR2ϪBH3 entities which are less
prone to electrophilic attack. A strategy which solves both
problems at the same time may be envisaged in η3-co-
Their ν(CO) IR spectra (Experimental Section) are in ac-
cord with the C3 symmetry of the Mo(CO)3 chromophore
which is somewhat disturbed by the two different donor
functions in 2b so that the E band is split into two dis-
cernable components. The NMR data (Tables 1 and 2, Ex-
perimental Section) are in full accord with the assigned con-
stitution. Compound 2a is deprotonated at the alcohol
function by KOtBu (Scheme 2). The potassium alkoxide
thus obtained reacts with various electrophiles to produce
the corresponding ethers 3. The infrared and 31P-NMR
Scheme 1
1
spectra (Experimental Section) as well as the 13C- and H-
NMR data (Tables 1 and 2) are in full accord with the
structures. Compounds 3 are obtained as analytically pure
pale yellow microcrystalline solids, the structures of 3a and
3b have been determined by X-ray crystallography.[16]
While the above procedure relies upon transforming the
CH2OH function of 2a into a nuleophilic group, a method
1
Table 1. H-NMR data of 1b, 2b, 7, 8a, 8b, 9a, and 9b
1H NMR[a]
CH2P
CH2SBzl
CH2OR
SCH2Ph
R
H aromat.
1b, R ϭ H
2b, R ϭ H
2.35, d, 2 H, 4.4[b]
2.50, bs, 2 H
2.66, s, 4 H
2.35, bs, 4 H
3.52, s, 2 H
3.11, bs, 2 H
3.62, s, 4 H
3.98 3.83, 2d, 4 H,
13.5[c]
Ϫ
Ϫ
7.57Ϫ7.18, m, 20 H
7.57Ϫ7.18, m, 20 H
7, R ϭ CH2
8a, R ϭ Me
Ϫ
2.93, s, 4 H
2.81 2.74, 2d, 4 H,
12.7[c]
4.33, s, 2 H
3.25, s, 2 H
3.73, s, 2 H
3.68, s, 4 H
Ϫ
7.36Ϫ7.30, m, 10 H
7.53Ϫ7.25, m, 20 H
2.41, d, 2 H, 4.0[b]
3.03, s, 3 H
8b, R ϭ Et
2.44, d, 2 H, 3.8[b]
2.81, s, 4 H
3.35, s, 2 H
3.71, s, 4 H
3.22, q, 2 H, 6.9[d] 1.09, t, 3 H, 7.58Ϫ7.27, m, 20 H
6.9[d]
3.27, s, 3 H
9a, R ϭ Me
9b, R ϭ Et
2.43, d, 2 H, 7.4[b]
2.46Ϫ2.40, m, 2 H
2.39, s, 4 H
2.40, s, 4 H
2.98, d, 2 H, 1.0[e]
3.03, s, 2 H
3.68, s, 4 H
4.00 3.93, 2d, 4 H,
15.0[c]
7.53Ϫ7.25, m, 20 H
3.40, q, 2 H, 6.9[d] 1.17, t, 3 H, 7.90Ϫ7.34, m, 20 H
6.9[d]
[b] 2
[c] 2
[d] 3
[e] 4
[a] 1b, 7 and 8 in CDCl3, 2b in [D8]THF, 9 in CD2Cl2. Ϫ
J
. Ϫ
HP
J
. Ϫ
J
. Ϫ
J
in Hz.
HP
HH
HH
Table 2. 13C-NMR data of 1b, 2b, 7, 8a, 8b, 9a, and 9b
13C NMR[a]
CH2P
CH2SBzl
CH2OR
SCH2Ph
CqCH2O
R
CO
C aromat.
1b, R ϭ H
2b, R ϭ H
34.1, d, 15.5[c] 38.0, d, 10.1[d] 66.6, d, 8.3[d]
31.5, d, 12.9[c] 36.5, d, 4.6[d] 73.5, d, 9.2[d]
37.4, s
43.8, d, 10.9[e]
43.5, d, 4.6[e]
Ϫ
Ϫ
Ϫ
137.9Ϫ126.8, m
139.6Ϫ128.4, m
48.8, d, 5.5[d]
223.4, d, 8.3[f],
220.3, d, 34.9[g]
Ϫ
Ϫ
Ϫ
7, R ϭ CH2
8a, R ϭ Me
8b, R ϭ Et
9a, R ϭ Me
9b, R ϭ Et
Ϫ
37.5Ϫ37.3, 2s[b] 79.8, s
37.5Ϫ37.3,2s[b] 43.6, s
38.3, s
Ϫ
137.9Ϫ126.9, 4s
139.8Ϫ127.4, m
140.0Ϫ127.3, m
138.1Ϫ128.4, m
138.1Ϫ128.4, m
35.0, d, 17.0[c] 38.7, d, 10.3[d] 76.0, d, 8.4[d]
35.0, d, 16.9[c] 38.7, d, 10.3[d] 73.6, d, 8.7[d]
44.0, d, 13.4[e] 58.7, s
38.3, s
44.0, d, 13.3[e] 66.6, s; 15.5, s
31.5, d, 11.7[c] 35.9, d, 4.4[d]
31.5, d, 12.0[c] 35.8, d, 4.2[d]
82.1, d, 8.8[d]
81.1, d, 9.2[d]
48.3, d, 5.8[d]
48.2, d, 5.8[d]
42.1, d, 5.5[e]
42.2, d, 5.2[e]
59.5, s
223.4, m
67.3, s; 15.1, s 223.3, d, 9.0[f],
220.1, d, 35.0[g]
[a]
[b]
[c] 1
[d] 3
[e] 2
1b, 7 and 8 in CDCl3, 2b in [D8]THF, 9 in CD2Cl2. Ϫ
Assignment not unambigously possible. Ϫ
J
. Ϫ
CP
J
. Ϫ
CP
J . Ϫ
CP
[f] COcis-P. Ϫ [g] COtrans-P
.
1408
Eur. J. Inorg. Chem. 1998, 1407Ϫ1415

Functionalized Ether Derivatives of HOCH2C(CH2PPh2)3 and Related Tripod Ligands
FULL PAPER
Scheme 2
tity of which is evident from the 31P-NMR and analytical
1
data (Experimental Section) as well as from H- and 13C-
NMR results (Tables 4 and 5).
Modification of Free Ligands
It had been shown that ether formation from 1a is not
possible under standard Williamson conditions.[8k] Neither
change of the solvent nor change of the counter ion (Naϩ,
Liϩ) was found to be a remedy in this situation[8k], nor did
BH3 protection of the phosphane donors cause a positive
change. Lacking reactivity or quaternization at the phos-
Scheme 3
Scheme 4
phorus atoms were the seemingly unavoidable prob-
lems.[8k]11] We found now that 1a after deprotonation with
KOtBu in THF does react with various electrophiles at tem-
peratures below 20°C to give the corresponding ethers
(Scheme 5).
Scheme 5
inverting the polarity by mesylation of the hydroxy group
is also possible.
2a, when treated with an excess of mesyl chloride in the
presence of NEt3 (Scheme 3), gives the mesylate 4 which
after chromatography is obtained analytically pure as a pale
yellow microcrystalline solid (Experimental Section; Tables
4 and 5). The mesylate 4 reacts with LiOEt to give 3b albeit
in lower yields as compared to the yields obtained using the
above procedure based on an inverted polarity. The pro-
cedure starting from 4 was therefore not further gen-
eralized. It should be noted that the free ligand
HOCH2C(CH2PPh2)(CH2Y)(CH2Z) can not be mesyl-
ated[11] and even a change of the reaction conditions as de-
scribed later did not work with mesyl chloride.
In order to make the above procedure useful for the syn-
thesis of the corresponding free ligands decoordination of
the Mo(CO)3 template in 3 is necessary. An especially useful
approach for this purpose has been developed by H. A.
Mayer et al.[12], who found that tripod ligands containing
Table 3. Alkylation reagents RX and yields for the reaction of 1a
to 5a؊h
R
X
Yield (%)
5a
5b
5c
5d
5e
5f
Me
I
72
69
33
44
38
52
Et
I
CH3[CH2]9
CH3[CH2]21
H2CϭCH[CH2]9
Cl[CH2]6
Me[OC2H4]3
Me[OC2H4]n, n ϭ 4Ϫ13
OTs
OTs
OTs
OTs
OTs
OTs
5g
5h
53
[a]
[a]
Yield cannot be determined due to separation problems of 5h
from the starting compounds.
The relative rates of ether formation or quaternization
P-donor functions may be decoordinated from their at the phosphorus atoms are different enough under these
Mo(CO)3 complexes by irridating their CH2Cl2 solutions in conditions to impede the extensive formation of quaterni-
the presence of pyridine N-oxide. With 3b as an example zation products. As minor side products the phosphonium
this procedure was shown to work equally well for the class salts are separated by chromatography from the products 5
of tripod ligands which are of concern in this paper. 3b and the ligands 5 are obtained in fair yields by this pro-
liberates the tripod ligand 5b (Scheme 4).
cedure. They are colorless viscous oils in general; only 5a
The ligand has to be purified by chromatography since could be obtained as a microcrystalline solid by recrystalli-
even under these specialized conditions oxidation at the zation from CH2Cl2. The compounds 5aϪ5g are obtained
phosphorus atoms is a minor side reaction. 5b is obtained in an analytically pure state; the polyoxyethylene derivative
as an analytically pure colorless viscous material, the iden- 5h is not completely separated from the starting materials.
Eur. J. Inorg. Chem. 1998, 1407Ϫ1415
1409

P. Schober, R. Soltek, G. Huttner, L. Zsol
FULL PAPER
1
Table 4. H-NMR data of 2, 3, 4, and 5
[a]
1H NMR
CH2P
CH2OR
R
H aromat.
2a, R ϭ H
2.30, br. s, 6H
2.31, br. s, 6H
2.35, br. s, 6H
2.37, br. s, 6H
2.36, br. s, 6H
2.32, br. s, 6H
3.56, br. s, 2 H
Ϫ
7.00Ϫ7.40, m, 30 H
7.44Ϫ7.05, m, 30 H
7.43Ϫ7.06, m, 30 H
7.37Ϫ7.05, m, 30 H
7.61Ϫ7.06, m, 41 H
7.37Ϫ7.04, m, 30 H
3a, R ϭ Me
3.28, br. s, 2 H 3.48, s, 3H
3b, R ϭ Et
3c, R ϭ Bzl
3d, R ϭ 4-stilbenyl
3e, R ϭ Br[CH2]6
3.36, br. s, 2 H 3.63, q, 2 H, 7.0[c]; 1.31, t, 3 H, 7.0[c]
3.45, br. s, 2 H 4.66, s, 2H
3.44, br. s, 2 H 4.66, s, 2H
3.32, br. s, 2 H 3.55, t, 6.3[c], CH2O; 3.42, t, 6.7[c], CH2Br;
1.89Ϫ1.50, m, 8 H, CH2CH2CH2
4, R ϭ CH3SO2
5a, R ϭ Me
5b, R ϭ Et
2.32, br. s, 6H
4.11, br. s, 2 H 3.11, s, 3H
7.35Ϫ7.06, m, 30 H
7.27Ϫ7.43, m, 30 H
7.26Ϫ7.40, m, 30 H
7.90Ϫ7.34, m, 30 H
7.27Ϫ7.60, m, 30 H
7.29Ϫ7.44, m, 30 H
2.61, d, 6 H, 2.6[b] 3.06, s, 2 H
2.52, d, 6 H, 2.4[b] 3.11, s, 2 H
2.68, d, 6 H, 2.5[b] 3.11, s, 2 H
2.55, d, 6 H, 2.4[b] 3.16, s, 2 H
2.51, s, 3H
0.7, t, 3 H, 6.9[c]; 2.62, q, 2 H, 7.0[c]
1.0, t, 3 H, 5.6[c]; 1.1Ϫ1.5, m, 16 H
0.94Ϫ3.39, m, 45 H; 3.39, m, 2 H
1.1Ϫ1.6, m, 14 H; 2.11, m, 2H; 2.73, m, 2H;
5.04, m, 2 H; 5.92, m, 2 H
5c, R ϭ CH3[CH2]9
5d, R ϭ CH3[CH2]21
5e, R ϭ H2CϭCH[CH2]9 2.63, d, 6 H, 2.3[b] 3.21, s, 2 H
5f, R ϭ Cl[CH2]6
2.59, d, 6 H, 2.6[b] 3.21, s, 2 H
2.55, d, 6 H, 2.5[b] 2.86, s, 2 H
2.56, d, 6 H, 2.6[b] 3.21, s, 2 H
1Ϫ1.5, m, 6H; 1.7, q, 2 H, 6.8[c]; 2.73, t, 2 H, 7.28Ϫ7.45, m, 30 H
6.0[c]; 3.50, t, 2 H, 6.8[c]
5g, R ϭ Me[OC2H4]3
5i, R ϭ NC[CH2]6
2.86, m,2H; 3.18, m, 4 H; 3.37, s, 3H;
7.25Ϫ7.37, m, 30 H
3.51Ϫ3.56, m, 8 H
1.1Ϫ1.6, m, 10 H; 2.22, t, 2 H, 7.0[c]; 2.71, m, 7.27Ϫ7.39, m, 30 H
2 H
5j, R ϭ HOOC[CH2]6
5k, R ϭ HOH2C[CH2]6
2.57, d, 6 H, 2.4[b] 3.18, s, 2 H
2.56, d, 6 H, 2.6[b] 3.21, s, 2 H
1.1Ϫ1.5, m, 8 H; 2.32, m, 2H; 2.71, m, 2 H
1.1Ϫ1.6, m, 10 H; 2.22, m, 2H; 2.70, m, 2 H
7.27Ϫ7.40, m, 30 H
7.27Ϫ7.39, m, 30 H
[b] 2
[c] 3
[a] 3 and 4 in CD2Cl2, 2 and 5 in CDCl3. Ϫ
J
. Ϫ
HP
J
in Hz.
HH
Table 5. 13C-NMR data of 3, 4, and 5
13C NMR[a]
CH2P
CH2OR
CqCH2OR
R
C aromat.
CO
[e]
3a, R ϭ Me
3b, R ϭ Et
32.9Ϫ32.4, m 87.5, q, 9.8[b]
31.6Ϫ31.1, m 84.1, q, 9.8[b]
42.8, q, 6.4[c]
41.6, q, 6.4[c]
60.8, s
139.9Ϫ129.6, m
67.4, s; 15.4, s
139.6Ϫ128.4, m 221.7Ϫ221.2,
m
3c, R ϭ Bzl
31.5Ϫ31.0, m 83.6, q, 9.5[b]
31.5Ϫ31.0, m 83.5, q, 9.5[b]
31.5Ϫ31.0, m 84.3, q, 9.6[b]
41.6, q, 6.4[c]
41.6, q, 6.6[c]
41.6, q, 6.5[c]
73.7, s
73.4, s
139.4Ϫ127.9, m 221.6Ϫ221.1,
m
3d, R ϭ 4-stilbenyl
3e, R ϭ Br[CH2]6
139.4Ϫ126.8, m 221.6Ϫ221.0,
m
71.7, 34.5, 33.3, 30.0, 28.4, 139.5Ϫ128.3, m 221.8Ϫ221.1,
26.0, 6s
m
[e]
4, R ϭ CH3SO2
5a, R ϭ Me
32,2Ϫ31.7, m 80.8, q, 10.1[b] 42.4, q, 7.4[c]
39.5, s
139.8Ϫ129.8, m
139.7Ϫ128.0, m
138.9Ϫ128.1, m
140.5Ϫ128.7, m
140.5Ϫ128.6, m
37.8, d, 8.9[d]
78.36, s
42.4, m
42.5, m
43.1, m
43.2, m
57.3, s
Ϫ
Ϫ
Ϫ
Ϫ
5b, R ϭ Et
37.5, m, 8.0[d] 85.4, s
38.5, m, 9.0[d] 71.1, s
14.4, s; 65.3, s
5c, R ϭ CH3[CH2]9
14.7, s; 23.2Ϫ32.4, m,
26.5Ϫ34.3, m; 77.2, m;
114.6, s; 139.7, s
21.0Ϫ28.3, m; 65.7, s
58.8, s; 69.6Ϫ71.7, m
18.0Ϫ25.0, m
5e, R ϭ H2CϭCH[CH2]9 38.5, d, 8.5[d]
71.0, s
5f, R ϭ Cl[CH2]6
5g, R ϭ Me[OC2H4]3
5i, R ϭ NC[CH2]6
5j, R ϭ HOOC[CH2]6
5k, R ϭ HOH2C[CH2]6
35.3, m
66.1, s
71.7, s
40.1, m
42.6, m
138.8Ϫ124.0, m
139.6Ϫ128.0, m
140.1Ϫ128.7, m
Ϫ
Ϫ
Ϫ
37.7, d, 8.8[d]
38.3, m
38.4, d, 9[d]
38.3, m
70.8, s
43.2, m
25.1Ϫ34.6, m, 179.8, s
18.0Ϫ25.0, m
140.6 Ϫ 128.7, m Ϫ
140.1Ϫ128.7, m
[b] 3
[c] 2
[d] 1
[a] 3 and 4 in CD2Cl2, 5 in CDCl3. Ϫ
J
. Ϫ
CP
J
. Ϫ
CP
J
in Hz. Ϫ [e] Due to worse solubility not observed.
CP
The presence of different chain lengths in the product 5h is MeI and also in EtI as the electrophilic components, it is
evident from the mass spectra (Experimental Section) as not apt for the introduction of components which contain
well as from individual chromatographic bands for the longer chain alkyl constituents (5e؊5f). In these cases, pre-
major congeners of the mixture of oligomers acting as the sumably by the elimination of HI, no products 5 are ob-
auxiliary groups in 5h. All compounds 5 show their 31P res- tained. Using tosylate instead of iodide as the leaving group
onances as a singlett at δ ഠ Ϫ28 (Experimental Section) as allows for the introduction of long-chain residues (5c؊5f).
usual for the CH2PPh2 groups in tripod ligands.[8l] The 1H- These residues may well contain ω-olefinic functionalities
NMR spectra of 5a؊5g (Table 4) show the signals of all (e.g. 5f). The monomethylpolyoxyethylene function (5g, 5h)
the chemically different groups of 5 in the correct integral may as well be introduced, with the corresponding tosylates
ratio and with the expected JCP couplings. The 13C-NMR which are themselves easily obtained from the commercial
data (Table 5) are equally conclusive as to the constitution alcohols.[13] With the tris(oxyethylene) building block,
of the compounds.
which is commercially available as its analytically pure al-
It is observed that while iodide as a leaving group of the cohol derivative 5g, is formed correspondingly. The distri-
electrophile used to form the ether linkage works well in bution characterizing the polymer mixture Me(OC2H4)nOH
1410
Eur. J. Inorg. Chem. 1998, 1407Ϫ1415

Functionalized Ether Derivatives of HOCH2C(CH2PPh2)3 and Related Tripod Ligands
FULL PAPER
leads to a corresponding distribution of chain lengths in Scheme 8
the product. The spread of compounds 5aϪ5h shows that
lipophilizing as well as hydrophilizing (5g, h) auxiliary
groups may equally well be introduced by the above pro-
cedure. Examples 5e, 5f show that ω functionalization of
alkyl chains is tolerated by the synthetic procedure, while
further functionalization of the terminal double bond in 5e
has not yet been analyzed. Substitution of the chlorine
function in 5f has been investigated: 5f in DMSO reacts
with an excess of KCN to give the nitrile derivative 5i which
lends itself to a variety of further transformations (Scheme
6).
equivocally characterized by their analytical and spectro-
scopic data (Experimental Section; Tables 1 and 2).
Compounds 8 contain three different ligand functionali-
ties in principle (PPh2, SBzl, OR). If they undergo η3 coor-
dination, different possibilities with respect to the formation
of isomers exist in principle. It is observed that with the
“soft” template Mo(CO)3 only the P- and S-donor func-
tions coordinate.
Scheme 6
Scheme 9
In order to test whether the reaction conditions just de-
scribed would also work when other donor groups besides
phosphanes are present in hydroxy-functionalized ligands
of type 1 the mixed-donor set ligand 1b was synthesized.
[14]
Upon reaction of 8 with (CH3CN)3Mo(CO)3
the de-
Scheme 7
rivatives 9 are formed which contain the ligand in an η3
coordination mediated by the two SBzl functions and the
PPh2 group (Scheme 9). Compounds 9 are microcrystalline
yellow solids which are fully characterized with their ana-
lytic and spectroscopic data (Experimental Section; Tables
1 and 2). In compounds 9 as in compound 2b two sets of
The functionalized oxetane 6 was transformed into 7 by carbonyl groups are expected. The 13C-NMR resonances
reaction with LiSBzl. In a consequent step the oxetane ring clearly distinguish between these two sets: the CO group
in 6 was nucleophilically opened by LiPPh2 (Scheme 7). trans to the phosphorus donor shows a large 2JCP coupling
After workup, 1b was obtained as a colorless oil of moder- constant: (2b: 34.9 Hz; 9b: 35.0 Hz) while the two carbonyl
ate viscosity. The sequence of reactions used to form groups cis to the phosphorus atom are characterized by
1b from the functionalized oxetane 6 had already been suc- coupling constants of around 9 Hz (Table 2). The idealized
cessfully applied in several principally analogous symmetry of the Mo(CO)3 entity is thus disturbed and as
cases.[8a][8b][8c][8d][8l] It corresponds to an entry into the described for 2b the ν(CO)-IR E bands of 9a and 9b are
chemistry of hydroxy-functionalized tripod ligands which is split into two distinct components (Experimental Section).
of rather broad scope. While 6 has already been de- The diastereotopicity of some of the CH2 groups in 9 is
1
scribed[8g] compounds 7 and 1b have been unknown and only occasionally resolved in their H-NMR (Table 1). The
have therefore been fully characterized by elemental analy- same statement applies for the diastereotopic differentation
sis, mass spectrometry and 31P-NMR data where appropri- of some of the CH2 groups in 8, 1b, and 2b (Table 1). While
ate (Experimental Section) as well as by 1H- and 13C-NMR with the selective coordination of P and S donors in 9 and
data (Tables 1 and 2).
the consequent exclusion of the OR donor from coordi-
The hydroxy function in 1b is indeed transformed into an nation, no problems arise with respect to the formation of
ether functionality under the conditions which have been a mixture of isomers it might well be that a template less
found to be productive in the transformation of 1aϪ5 soft than Mo(CO)3 might change the situation. To test this
(Scheme 8). Compounds 8 are colorless oils which are un- hypothesis 5a containing three phosphorus and one oxygen
Eur. J. Inorg. Chem. 1998, 1407Ϫ1415
1411

P. Schober, R. Soltek, G. Huttner, L. Zsol
FULL PAPER
[8l][8m][8n][8o]
(516.7): calcd. C 72.07, H 6.44; found C 71.72, H 6.49. Ϫ
MS(FAB); m/z (%): 517 (18) [Mϩ ϩ 1], 425 (100) [Mϩ Ϫ C7H7]. Ϫ
donors was treated with [Fe(CH3CN)6](BF4)2
(Scheme 10).
1
31P{1H} NMR (CDCl3): δ ϭ Ϫ26.0 (s). Ϫ For H- and 13C-NMR
data see Tables 1 and 2.
Scheme 10
General Procedure for the Preparation of the Molybdenum Com-
plexes 2 and 9: The given tripod ligands (vide infra) were dissolved
in CH2Cl2 (30 ml), solid (CH3CN)3Mo(CO)3 was added (302 mg;
1 mmol) and the mixtures were stirred for 1 h at room temperature.
During the reactions the (CH3CN)3Mo(CO)3 slowly dissolved and
the colors of the solutions turned from light-yellow into yellow-
brown. The reaction mixtures were concentrated to 5 ml and slow
stepwise addition of 50 ml of petroleum ether (40/60) gave yellow to
yellow-brownish, microcrystalline solids. The crude products were
washed with petroleum ether (40/60) (2 ϫ 50 ml) and diethyl ether
The propensity of the starting material to form tris(ace-
tonitrile)iron cations had already been demonstrat-
ed.[8l][8m][8n][8o] With 5 as the ligand compound 10 is ob- (2 ϫ 50 ml) and dried in vacuo.
Follwing the above procedure using 1b (517 mg; 1 mmol) as the
tained as the only product. No signs of oxygen coordination
are thus observed even when the less soft metal center FeII
as compared to Mo0 in 9 is coordinated. 10 is fully charac-
terized by the usual analytical and spectroscopic techniques
(Experimental Section).
tripod ligand yielded 490 mg (70%) of 2b, m.p. 220°C (dec.). With
1a (640 mg; 1 mmol) as the tripod ligand 740 mg (90%) of 2a
were obtained, m.p. 225°C (dec.). Starting the procedure described
above with 8a (530 mg; 1 mmol) led to 600 mg (84%) of 9a, m.p.
210°C (dec.). Crystals suitable for an X-ray analysis were obtained
for 9a by slow diffusion of diethyl ether into a solution of 100 mg
of the microcystalline product in 5 ml of a mixture of CH2Cl2/
toluene (1:1) at room temperature after 2 d. 650 mg (90%) 9b, m.p.
205°C (dec.) was obtained if the starting compound for the above
procedure was 8b (545 mg; 1 mmol).
2a: C44H39MoO4P3 (820.7): Ϫ MS (EI); m/z (%): 822 (4) [Mϩ],
738 (60) [Mϩ Ϫ 3 CO], 523 (100) [Mϩ Ϫ 3 CO Ϫ C7H7]. Ϫ IR
(CH2Cl2): ν˜(CO) ϭ 1937 cmϪ1 (s), 1845 (s, br.). Ϫ 31P{1H} NMR
(CD2Cl2): δ ϭ 14.5 (s).
Experimental Section
General: All manipulations were carried out under argon by me-
ans of standard Schlenk techniques. All solvents were dried by
standard methods and destilled under argon. The CDCl3, CD2Cl2,
and [D8]THF used for the NMR-spectroscopic measurements were
degassed by three successive “freeze-pump-thaw” cycles and dried
˚
over 4-A molecular sieves. The silica gel (Kieselgel z.A. 0.06Ϫ0.2
2b: C34H33MoO4PS2 (696.7): calcd. C 58.45, H 4.76, P 4.44, S
9.16; found C 57.39, H 4.99, P 4.29, S 8.87. Ϫ MS (FAB); m/z (%):
698 (36) [Mϩ], 614 (44) [Mϩ Ϫ 3 CO], 523 (100) [Mϩ Ϫ 3 CO Ϫ
C7H7]. Ϫ IR (CH2Cl2): ν˜(CO) ϭ 1932 cmϪ1 (s), 1829 (s, br.); 1817
(vs, br.). Ϫ 31P{1H} NMR ([D8]THF): δ ϭ 20.2 (s).
mm, J. T. Baker Chemicals B.V.) used for chromatography was de-
gassed at 1 mbar for 24 h and saturated with argon. Ϫ NMR:
Bruker Avance DPX 200 at 200.13 MHz (1H), 50.323 MHz
(13C{1H}), 81.015 MHz (31P{1H})); chemical shifts (δ) in ppm with
respect to CDCl3 (1H: δ ϭ 7.27; 13C: δ ϭ 77.0), CD2Cl2 (1H: δ ϭ
5.32; 13C: δ ϭ 53.5) and [D8]THF (1H: δ ϭ 3.58; 13C: δ ϭ 67.7) as
internal standards, and chemical shifts (δ) in ppm with respect to
85% H3PO4 (31P: δ ϭ 0) as external standard. Ϫ IR: Bruker FT-
IR IFS-66; CaF2 cells. Ϫ MS: Finnigan MAT 8400; FAB: Nibeol
(4-nitrobenzyl alcohol) or TEA (triethanol amine) matrices, respec-
tively; EI: 70 eV. Ϫ Elemental analyses: Microanalytical laboratory
of the Organisch-Chemisches Institut, Universität Heidelberg:
With the equipment used, carbon values tend to be systematically
too low in the presence of molybdenum or/and boron. Some of the
analytical data given have to be interpreted with this in mind. Ϫ
Melting points: Gallenkamp MFB-595 010; melting points are not
9a: C35H35MoO4PS2 (710.7): calcd. C 59.15, H 4.96, P 4.36, S
9.03; found C 57.66, H 5.06, P 4.16, S 8.80. Ϫ MS (FAB); m/z (%):
712 (14) [Mϩ], 537 (4) [Mϩ Ϫ 3 CO Ϫ C7H7]. Ϫ IR (CH2Cl2):
ν˜(CO) ϭ 1932 cmϪ1 (s), 1829 (v, br.), 1815 (s, br.). Ϫ 31P{1H}
NMR ([D8]THF): δ ϭ 17.2 (s). Ϫ X-ray analysis see ref.[16]
.
9b: C36H37MoO4PS2 (724.7): calcd. C 59.66, H 5.15, P 4.27, S
8.85; found C 58.94, H 4.99, P 4.21, S 8.86. Ϫ MS (FAB); m/z (%):
726 (18) [Mϩ], 642 (5) [Mϩ Ϫ 3 CO], 551 (20) [Mϩ Ϫ 3 CO Ϫ
C7H7]. Ϫ IR (CH2Cl2): ν˜(CO) ϭ 1932 cmϪ1 (s), 1829 (s, br.), 1815
(s, br.). Ϫ 31P{1H} NMR (CD2Cl2): δ ϭ 16.1 (s).
1
For H- and 13C-NMR data see Tables 1 and 2.
corrected. Ϫ The oxetane 6 was prepared according to ref.[8g]
.
[(CH3CN)3Mo(CO)3] was obtained as described in ref.[14]. All other
chemicals were commercially obtained and used without further
purification.
General Procedure for the Preparation of the Molybdenum Com-
plexes 3 by Alkylation of 2a: Compound 2a (815 mg; 1 mmol) was
dissolved in THF (50 ml) and deprotonated with KOtBu (112 mg;
1 mmol). While stirring the mixture for 1 h a light-yellow precipi-
tate of the potassium salt of 2a formed. The alkylation reagent as
specified below was added. The mixture was stirred for 2 h during
which the precipitate formed in the deprotonation step slowly dis-
solved again. The completion of the reaction was determined by
TLC control: CH2Cl2/petroleum ether (40/60), 3:1; 2a: Rf ϭ 0.35
(tailing); 3: Rf ϭ 0.67Ϫ0.74 (no tailing). After removal of the sol-
vent, the resulting residue was chromatographed on silica gel (10
cm, Ø ϭ 4 cm). The fractions eluted with a mixture of CH2Cl2/
petroleum ether (40/60), 3:1 (TLC control: Rf ϭ 0.67Ϫ0.74) gave
pale-yellow microcrystalline solids.
Preparation of 1b: A solution of lithium diphenylphosphide in
THF (100 ml) was prepared by deprotonation of diphenylphos-
phane (8.2 g; 44 mmol) with n-butyllithium (17.6 ml; 44 mmol; 2.5
 in n-hexane) at 0°C. After stirring for 30 min, a solution of 7
(13.2 g; 40 mmol) in THF (100 ml) was added and the mixture
refluxed for 2 h. The solvent was removed, water (100 ml) and
diethyl ether (100 ml) were added, and the mixture was neutralized
with 37% HCl. The aqueous phase was extracted with diethyl ether
(2 ϫ 100 ml) and the combined organic phases were dried and
concentrated. The resulting residue was chromatographed on silica
gel (20 cm, Ø ϭ 10 cm). The fraction eluted with a mixture of
petroleum ether (40/60)/diethyl ether (6:4; TLC control: Rf ϭ 0.48)
Following the above procedure compounds 3 were obtained by
gave 15.5 g of 1b as a colorless oil in 75% yield. Ϫ C31H33OPS2 using as alkylation reagent CH3I (284 mg, 2 mmol) to prepare 3a
1412 Eur. J. Inorg. Chem. 1998, 1407Ϫ1415

Functionalized Ether Derivatives of HOCH2C(CH2PPh2)3 and Related Tripod Ligands
(790 mg, 95%), triethyloxonium tetrafluoroborate (380 mg, 2 mmol) and the reaction mixture was irradiated in a “Duran 50”
FULL PAPER
mmol) to prepare 3b (510 mg, 60%), benzyl bromide (340 mg, 2 (“Pyrex”) apparatus with a mercury lamp (TQ 150 Hanau) at
mmol) to prepare 3c (820 mg, 91%), 4-chloromethylstilbene (460 Ϫ5°C for 1 h. After removal of the solvent the brownish residue
mg, 2 mmol) to prepare 3d (960 mg, 95%), and 6-bromo-n-hexyl was chromatographed on silica gel. The fractions eluted with a mix-
p-toluenesulfonate (670 mg, 2 mmol) to prepare 3e (360 mg, 37%).
Crystals suitable for X-ray analyses were obtained for 3a and for
3b by slow diffusion of diethyl ether into a solution of 100 mg of
the microcystalline products in 5 ml of CH2Cl2 at room tempera-
ture after 1 d.
ture of petroleum ether (40/60)/diethyl ether (9:1; TCL control:
Rf ϭ 0.40) gave 401 mg (60%) of 5b as a colorless, viscous oil. Ϫ
Analytical data: vide supra.
Preparation of 7: Compound 6 (13.0 g; 50 mmol) was dissolved
in THF (100 ml) and the solution cooled to 0°C. A solution of
lithium benzylthiolate (100 mmol in 300 ml of THF), obtained by
deprotonation of 12.4 g (100 mmol) of benzylthiole with 40 ml of
n-butyllithium (2.5  in n-hexane) at 0°C, was slowly added and
the mixture stirred for 4 h at room temperature to give a volumin-
ous white precipitate of lithium mesylate and lithium bromide. The
solvent was removed in vacuo, water (200 ml) and diethyl ether
(200 ml) were added and the mixture was neutralized with 37%
HCl. The aqueous phase was extracted with diethyl ether (2 ϫ 150
ml) and the combined organic phases were dried and concentrated.
Destillation of the residue (b.p. 205Ϫ210°C/1 mbar) yielded 14.9 g
(90%) of 7 as a viscous, colorless oil. Ϫ C19H22OS2 (330.5): calcd.
C 69.07, H 6.72, S 19.37; found C 68.81, H 6.50, S 18.68. Ϫ MS
(FAB); m/z (%): 331 (72) [Mϩ ϩ 1], 239 (100) [Mϩ Ϫ C7H7]. Ϫ For
1H- and 13C-NMR data see Tables 1 and 2.
3a: C45H41MoO4P3 (834.7): calcd. C 64.58, H 4.92, P 11.12;
found C 63.90, H 5.24, P 10.89. Ϫ MS (EI); m/z (%): 836 (30) [Mϩ],
808 (36) [Mϩ Ϫ CO], 780 (60) [Mϩ Ϫ 2 CO], 752 (100) [Mϩ Ϫ 3
CO]. Ϫ IR (CH Cl ): ν(CO) ϭ 1932 cmϪ1 (s), 1835 (s, br.). Ϫ
˜
2
2
31P{1H} NMR (CD2Cl2): δ ϭ 16.0 (s). Ϫ X-ray analysis see ref.[16]
.
3b: C46H43MoO4P3 (848.7): calcd. C 64.93, H 5.10, P 10.93;
found C 64.87, H 5.26, P 10.76. Ϫ MS (EI); m/z (%): 850 (20) [Mϩ],
821 (30) [Mϩ Ϫ CH2CH3], 793 (58) [Mϩ Ϫ CO Ϫ CH2CH3], 766
(100) [Mϩ Ϫ 3 CO]. Ϫ IR (CH2Cl2): ν˜(CO) ϭ 1929 cmϪ1 (s), 1833
(s, br.). Ϫ 31P{1H} NMR (CD2Cl2): δ ϭ 15.9 (s). Ϫ X-ray analysis
see ref.[16]
.
3c, C51H45MoO4P3 (910.7): calcd. C 67.26, H 4.98, P 10.20;
found C 66.78, H 5.18, P 10.06. Ϫ MS (FAB); m/z (%): 912 (46)
[Mϩ], 884 (30) [Mϩ Ϫ CO], 856 (34) [Mϩ Ϫ 2 CO], 828 (35) [Mϩ
Ϫ 3 CO]. Ϫ IR (CH2Cl2): ν˜(CO) ϭ 1929 cmϪ1 (s), 1829 (s, br.). Ϫ
31P{1H} NMR (CD2Cl2): δ ϭ 15.8 (s).
Preparation of 8a and 8b: For the synthesis of 8a a solution of
1b (5.17 g; 10 mmol) in THF (100 ml) was deprotonated with
KOtBu (1.12 g; 10 mmol). The mixture was cooled to Ϫ15°C, then
CH3I (1,42 g; 10 mmol) was slowly added (temperature was held
below Ϫ10°C) and a white precipitate of potassium iodide instan-
taneously formed. The progress of the reaction was determined by
TLC [petroleum ether (40/60)/diethyl ether, 6:4; 1b: Rf ϭ 0.48; 8a:
Rf ϭ 0.80].
3d: C59H51MoO4P3 (1012.9): calcd. C 69.96, H 5.54; found C
69.40, H 5.54. Ϫ MS (FAB); m/z (%): 1014 (80) [Mϩ], 986 (36) [Mϩ
Ϫ CO], 958 (64) [Mϩ Ϫ 2 CO], 930 (54) [Mϩ Ϫ 3 CO]. Ϫ IR
(CH2Cl2): ν˜(CO) ϭ 1937 cmϪ1 (s), 1844 (s, br.). Ϫ 31P{1H} NMR
(CD2Cl2): δ ϭ 15.7 (s).
3e: C50H50BrMoO4P3 (983.7): calcd. C 61.05, H 5.12; found C
62.18, H 5.51. Ϫ MS (FAB); m/z (%): 984 (80) [Mϩ], 956 (50) [Mϩ
Ϫ CO], 928 (68) [Mϩ Ϫ 2 CO], 900 (100) [Mϩ Ϫ 3 CO]. Ϫ IR
To synthesize 8b a slightly modified procedure was applied: A
solution of 1b (2.58 g, 5 mmol) in 50 ml of THF was deprotonated
with KOtBu (560 mg, 5 mmol). The mixture was cooled to 0°C,
iodethane (780 mg, 5 mmol) was slowly added and a white precipi-
tate of potassium iodide slowly formed. After 10 min, the progress
of the reaction was determined by TLC control [petroleum ether
(40/60)/diethyl ether, 6:4; 1b: Rf ϭ 0.48; 8b: Rf ϭ 0.81]. After the
first “deprotonation-alkylation” sequence, the reaction was incom-
plete. For obtaining higher yields it was necessary to repeat this
sequence five times. The isolation procedures for 8a and 8b were
similar:
(CH Cl ): ν(CO) ϭ 1937 cmϪ1 (s), 1844 (s, br.).
˜
2
2
1
For H- and 13C-NMR data see Tables 3 and 4.
Preparation of 4: NEt3 (600 mg, 6 mmol) and methanesulfonyl
chloride (570 mg, 5 mmol) were added to a solution of 2a (819 mg,
1 mmol) in CH2Cl2 (50 ml). After stirring the light-yellow mixture
for 30 min, water was added (50 ml). After separation of the phases,
the aqueous phase was extracted with CH2Cl2 (2 ϫ 50 ml) and the
residue of the dried (MgSO4) and concentrated organic phases was
chromatographed on silica gel (10 cm, Ø ϭ 4 cm). Concentrating
the fractions eluted with a mixture of CH2Cl2/petroleum ether (40/
60) (3:1; TLC control: Rf ϭ 0.50) gave 4 as a pale-yellow microcrys-
talline product (810 mg, 90%). Ϫ C45H41BrMoO6P3S (898.7):
calcd. C 60.14, H 4.60; found C 58.71, H 4.73. Ϫ MS (EI); m/z
(%): 899 (20) [Mϩ Ϫ 1], 872 (26) [Mϩ Ϫ CO], 844 (60) [Mϩ Ϫ 2
CO], 816 (100) [Mϩ Ϫ 3 CO]. Ϫ IR (CH2Cl2): ν˜(CO) ϭ 1927 cmϪ1
(s), 1844 (s), 1826 (s). Ϫ 31P{1H} NMR (CD2Cl2): δ ϭ 14.0 (s). Ϫ
After completion of the reaction, water was added (1 ml) and
the mixture was allowed to warm to 20°C. The solvent was re-
moved, water (100 ml) and diethyl ether (100 ml) were added und
the mixture was neutralized with 37% HCl. The aqueous phase was
extracted with diethyl ether (2 ϫ 100 ml) and the combined organic
phases were dried and concentrated. The resulting residue was
chromatographed on silica gel (15 cm, Ø ϭ 6 cm).
8a: The fraction eluted with a mixture of petroleum ether (40/
60)/diethyl ether (6:4; TLC control: Rf ϭ 0.8) gave 3.45 g of 8a as
a colorless oil in 65% yield. Ϫ C32H35OPS2 (530.7): calcd. C 72.42,
H 6.65, P 5.84; found C 71.95, H 7.03, P 5.46. Ϫ MS (FAB); m/z
(%): 531 (34) [Mϩ ϩ 1], 439 (100) [Mϩ Ϫ C7H7]. Ϫ 31P{1H} NMR
1
For H- and 13C-NMR data see Tables 3 and 4.
Preparation of 3b Starting from 4: To a solution of lithium ethox-
ide in THF (50 ml), prepared by deprotonation of ethanol (138 mg,
3 mmol) with 1.2 ml of n-butyllithium (2.5  in n-hexane) at 0°C,
4 (450 mg, 0.5 mmol) was added. After stirring the yellow mixture (CDCl3): δ ϭ Ϫ26.4 (s).
for 4 h at 50°C, the solvent was removed and the residue chroma-
8b: The fraction eluted with a mixture of petroleum ether (40/
tographed on silica gel (10 cm, Ø ϭ 4 cm). Concentrating the frac-
tions eluted with a mixture of CH2Cl2/petroleum ether (40/60) (3:1;
TLC control: Rf ϭ 0.73) gave 3b as a pale-yellow microcrystalline
product (148 mg, 35%). Ϫ Analytical data: vide supra.
60)/diethyl ether (9:1; TLC control: Rf ϭ 0.4) gave 1.91 g of 8b as
a colorless oil in a 70% yield. Ϫ C33H37OPS2 (544.8): calcd. C
72.75, H 6.85, P 5.59, S 11.77; found C 72.77, H 7.13, P 5.58, S
11.75. Ϫ MS (FAB); m/z (%): 545 (18) [Mϩ ϩ 1], 453 (100) [Mϩ Ϫ
C7H7]. Ϫ 31P{1H} NMR (CDCl3): δ ϭ Ϫ26.8 (s). ϪFor 1H- and
Liberating 5b from 3b: Compound 3b (829 mg, 1 mmol) was dis-
solved in CH2Cl2 (200 ml), pyridine N-oxide was added (1.90 g, 20 13C-NMR data see Tables 1 and 2.
Eur. J. Inorg. Chem. 1998, 1407Ϫ1415
1413

P. Schober, R. Soltek, G. Huttner, L. Zsol
FULL PAPER
General Procedure for the Preparation of Ethers 5 by Direct Alky-
lation of 1a: Compound 1b (640 mg; 1 mmol) was dissolved in
THF (20 ml) and cooled to Ϫ5°C by means of an ice/salt bath. 1.5
equivalents of KOtBu were added to the colorless solution, which
immediately turned yellow. The mixture was stirred for 5 min and
the given alkyl iodides or toluenesulfonic esters (vide infra) were
added. In case of the alkyl iodides the mixture immediately became
turbid white, in case of the toluenesulfonic esters the mixture was
slowly brought to room temperature and the mixture became tur-
bid yellow-brown. The completion of the reaction was determined
by TLC control. Water (0.5 ml) was added and the solvent was
removed in vacuo. The residue was dissolved in dichloromethane
and filtered through silica gel. The solvent was removed and the
residue was chromatographed on silica gel (15Ϫ25 cm, л ϭ 4 cm).
Ϫ
31P{1H} NMR (CDCl3): δ ϭ Ϫ28.3 (s). Ϫ For 1H- and 13C-
NMR data see Tables 3 and 4.
Preparation of 5j: A solution of 5i (430 mg , 0.6 mmol) in a 1:1
mixture of ethanol/water (25 ml) and KOH (580 mg, 10.4 mmol)
was heated under reflux for 4 h. After cooling, the reaction mixture
was acidified with 37% hydrochloric acid. The water phase was
extracted with dichloromethane (3 ϫ), the organic phase was dried
with MgSO4, the solvent was removed in vacuo and the residue
was chromatographed on silica gel. The fractions eluted with di-
ethyl ether at Rf ϭ 0.40 were collected to give 220 mg (48%) of 5j
as a colorless oil after evaporation of the solvent. Ϫ C48H51O3P3
(768.8): calcd. C 74.99, H 6.69; found C 74.42, H 6.82. Ϫ MS
(FAB); m/z (%): 768 (35) [Mϩ], 691 (100) [Mϩ Ϫ PPh2], 582 (21)
[Mϩ Ϫ PPh2]. Ϫ 31P{1H} NMR (CDCl3): δ ϭ Ϫ28.2 (s). Ϫ IR
1
Following the above procedure compounds 5 were obtained by
using as alkylation reagents iodomethane (982 mg, 6.91 mmol) to
prepare 5a (470 mg, 72%), iodoethane (200 mg, 1.33 mmol) to
prepare 5b (461 mg, 69%), n-decyl p-toluenesulfonate (667 mg, 2.14
mmol) to prepare 5c (253 mg, 33%), n-docosanyl p-toluenesulfon-
ate (510 mg, 1.06 mmol) to prepare 5d (425 mg, 44%), undecenyl
p-toluenesulfonate (475 mg, 1.46 mmol) to prepare 5e (300 mg,
38%), 6-chloro-n-hexyl p-toluenesulfonate (347 mg, 1.2 mmol) to
prepare 5f (394 mg, 52%), triethyleneglycol monomethyl ether p-
toluenesulfonic ester (400 mg, 1.25 mmol) to prepare 5g (415 mg,
53%).
(Nujol): ν˜(COO) ϭ 1708 cmϪ1 (m). Ϫ For H- and 13C-NMR data
see Tables 3 and 4.
Preparation of 5k: A solution of 5j (50 mg, 0.07 mmol) in THF
(5 ml) was added to a stirred suspension of LiAlH4 (30 mg, 0.8
mmol) in THF (5 ml). The mixture was heated under reflux for 2
h and after cooling to 20°C hydrolized with water. The products
of hydrolysis were washed with dichloromethane, the combined or-
ganic phases were dried (MgSO4) and the solvents were removed
in vacuo. The residue, a colorless oil, was investigated by mass spec-
trometry and NMR spectroscopy. Ϫ C48H53O2P3 (755). Ϫ MS
(FAB); m/z (%): 755 (27) [Mϩ], 678 (100) [Mϩ Ϫ PPh2], 571 (18)
[Mϩ Ϫ PPh2]. Ϫ 31P{1H} NMR (CDCl3): δ ϭ Ϫ28.1 (s). Ϫ For
1H-and 13C-NMR data see Tables 3 and 4.
5a: C42H41OP3 (654.1): calcd. C 77.04, H 6.32; found C 76.79,
H 6.37. Ϫ MS (EI); m/z (%): 654 (11) [Mϩ], 577 (100) [Mϩ Ϫ Ph],
469 (16) [Mϩ Ϫ PPh2]. Ϫ 31P{1H} NMR (CDCl3): δ ϭ Ϫ28.4 (s).
Preparation of 10: Compound 5a (654 mg, 1 mmol) was dissolved
in acetonitrile (20 ml) and 476 mg (1 mmol) of
[Fe(CH3CN)6](BF4)2, dissolved in 10 ml of acetonitrile, was added.
The mixture immediately turned red and was stirred at room tem-
perature for 1 h. The solvent was removed and the residue was
washed with diethyl ether (3 ϫ). After drying in vacuo, 930 mg
(92%) of 10 was obtained as a red powder. Crystals suitable for X-
ray analysis were obtained by diffusion of diethyl ether into a solu-
tion of 10 in CH2Cl2 within 1 d at room temperature. Ϫ
5b: C43H43OP3 (668.7): calcd. C 77.22, H 6.49; found C 75.51,
H 6.63. Ϫ MS (EI); m/z (%): 668 (10) [Mϩ], 591 (100) [Mϩ
Ϫ
PPh2], 485 (38) [Mϩ Ϫ PPh2]. Ϫ 31P{1H} NMR (CDCl3): δ ϭ
Ϫ28.3 (s).
5c: C51H59OP3 (780.5): calcd. C 78.48, H 7.56; found C 78.10, H
7.83. Ϫ MS (EI); m/z (%): 780 (9) [Mϩ], 703 (100) [Mϩ Ϫ PPh2],
595 (11) [Mϩ Ϫ PPh2]. Ϫ 31P{1H} NMR (CDCl3): δ ϭ Ϫ28.6 (s).
5d: C63H83OP3 (949.3): calcd. C 79.71, H 8.81; found C 79.34,
C
48H50B2F8FeN3OP3 (1007.4): calcd. C 57.23, H 5.00, N 4.17;
H 10.01. Ϫ MS (EI); m/z (%): 949 (17) [Mϩ], 872 (100) [Mϩ
Ϫ
found C 54.04, H 6.83, N 4.18. Ϫ MS (FAB); m/z (%): 729 (100)
[Mϩ Ϫ 3 MeCN Ϫ B2F7], 655 (73) [free ligand], 576 (52) [free
ligand-Ph]. Ϫ 1H NMR (CDCl3): δ ϭ 2.03 (br. s, 2 H, OCH2), 2.41
(br. s, 9 H, CH3CN), 2.58 (br. s, 6 H, CH2P), 3.61 (br. s, 3 H,
CH3O), 7.25-7.37 (br. m, 30 H, H arom.). Ϫ 13C{1H} NMR
(CDCl3): δ ϭ 4.9 (s, CH3CN); 129.3, 130.8, 132.4, 142 (m, C
arom.). Ϫ 31P{1H} NMR (CDCl3): δ ϭ ϩ31.7 (s). Ϫ IR (KBr):
PPh2], 764 (20) [Mϩ Ϫ PPh2]. Ϫ 31P{1H} NMR (CDCl3): δ ϭ
Ϫ25.3 (s).
5e: C52H59OP3 (792.5): calcd. C 78.75, H 7.50; found C 78.88, H
7.75. Ϫ MS (EI); m/z (%): 792 (20) [Mϩ], 715 (100) [Mϩ Ϫ PPh2].
31P{1H} NMR (CDCl3): δ ϭ Ϫ28.2 (s).
Ϫ
ν(CN) ϭ 2343 cmϪ1 (w), 2287 (m).
5f: C47H50ClOP3 (759.3): calcd. C 74.35, H 6.58; found C 73.77,
H 7.10. Ϫ MS (EI); m/z (%): 758 (10) [Mϩ], 681 (100) [Mϩ Ϫ PPh2],
573 (10) [Mϩ Ϫ PPh2]. Ϫ 31P{1H} NMR (CDCl3): δ ϭ Ϫ25.1 (s).
˜
Ƞ
Dedicated to Prof. Dr. Achim Müller, Universität Bielefeld, on
5g: C48H53OP3 (786.9): calcd. C 73.27, H 6.79; found C 73.10,
H 6.83. Ϫ MS(EI); m/z (%): 786 (9) [Mϩ], 709 (100) [Mϩ Ϫ PPh2],
601 (11) [Mϩ Ϫ PPh2]. Ϫ 31P{1H} NMR (CDCl3): δ ϭ Ϫ28.6 (s).
the occasion of his 60th birthday.
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