Reactions of Cp′(CO)2MnPPh2H with CH3COCl and CH3S(O)2Cl in THF/triethylamine: Evidence of the first complex stabilization of a phosphorus homolog of the sulfonamides

Article abstract of DOI:10.1016/S0020-1693(99)00015-8

The complex Cp′Mn(CO)₃ (Cp′=η⁵-C₅H₄-CH₃) reacts with P(C₆H₅)₂H in THF to give Cp′(CO)₂MnPPh₂H (Ph=phenyl) (1), by substitution of one CO ligand. The reaction of 1 with CH₃COCl and CH₃S(O)₂Cl in the presence of triethylamine occurs under electrophilic substitution on the diphenylphosphane ligand yielding the acetyl and sulfonylphosphane complexes of manganese(I) Cp′(CO)₂MnPPh₂COCH₃ (2) and Cp′(CO)₂MnPPh₂S(O)₂CH₃ (3). The complex stabilization of these molecules, which are hitherto unknown in the free state, is only accomplished by blocking the free electron pair on phosphorus by coordination. The new complexes 1, 2 and 3 were analyzed by IR, ¹H and ³¹P NMR spectroscopy and their similar structures are discussed.

Full text of DOI:10.1016/S0020-1693(99)00015-8

Inorganica Chimica Acta 288 (1999) 101–105
Note
Reactions of Cp%(CO)2MnPPh2H with CH3COCl and CH3S(O)2Cl
in THF/triethylamine: evidence of the first complex stabilization of
a phosphorus homolog of the sulfonamides
Gelson Manzoni de Oliveira a,*, Milton Seiffert a, Ingo-Peter Lorenz b
a Departamento de Qu´ımica, Uni6ersidade Federal de Santa Maria, Campus–Camobi, Santa Maria RS, 97105-900, Brazil
b Institut fu¨r Anorganische Chemie, Ludwig-Maximilians Uni6ersita¨t Mu¨nchen, Meiserstrasse 1, D-80333 Munich, Germany
Received 15 July 1998; accepted 25 November 1998
Abstract
The complex Cp%Mn(CO)3 (Cp%=h5-C5H4–CH3) reacts with P(C6H5)2H in THF to give Cp%(CO)2MnPPh2H (Ph=phenyl) (1),
by substitution of one CO ligand. The reaction of 1 with CH3COCl and CH3S(O)2Cl in the presence of triethylamine occurs under
electrophilic substitution on the diphenylphosphane ligand yielding the acetyl and sulfonylphosphane complexes of manganese(I)
Cp%(CO)2MnPPh2COCH3 (2) and Cp%(CO)2MnPPh2S(O)2CH3 (3). The complex stabilization of these molecules, which are
hitherto unknown in the free state, is only accomplished by blocking the free electron pair on phosphorus by coordination. The
1
new complexes 1, 2 and 3 were analyzed by IR, H and 31P NMR spectroscopy and their similar structures are discussed. © 1999
Elsevier Science S.A. All rights reserved.
Keywords: Manganese complexes; Cyclopentadienyl complexes; Carbonyl complexes; Acetylphosphane complexes; Sulfonylphosphane complexes
Belonging to this class of molecules, along with sev-
eral phosphanes bonded to acyl groups (acylphos-
1. Introduction
phanes), are the sulfinyl and the sulfonylphosphanes.
Organic unstable or reactive molecules can be stabi-
Contrary to their homolog, the sulfinamides and sul-
lized through the formation of transition metal com-
fonamides, these species were hitherto unknown. Many
plexes, a procedure of wide application in inorganic
synthesis attempts failed [6–8], probably due to in-
synthesis. Classical examples are p-complexes of
Fe(CO)3 with cyclobutadiene, trimethylenemethane, cy-
tramolecular redox reactions of the Arbusov–Michaelis
type [9,10]. Results obtained by Lorenz et al. [11,12]
clopentadienone and other similar species [1–3]. These
proved that these molecules can actuate as ligands in
molecules cannot be isolated under normal conditions
organometallic complexes, which leads to their
because of their ability to undergo internal rearrange-
stabilization.
ment in the free state [4,5]. Besides their actuation as
organometallic complexes forming ligands, these stabi-
The synthesis of phosphorus and phosphoryl com-
pounds analogous to the sulfonamides of the type
lized molecules generally maintain their individuality in
R(O)2SPR% and R(O)2SP(O)R% was attempted [13] by
2
2
the complex, for example, cyclobutadiene, in
Fe(CO)3(C4H4). This makes it possible to study their
properties [1].
the reaction of the phosphinyl chlorides R%P(O)Cl
2
(R%=CH3, C6H5) with silver sulfinates RSO2Ag (R=
CH3,
p-CH3C6H4).
Sulfinyl
phosphinates
RS(O)OP(O)R%, isomers from the desired sulfonylphos-
2
phane oxide, were spectroscopically detected in the
reaction product; nevertheless, only the anhydrides of
* Corresponding author. Tel.: +55-55-220 8757; fax: +55-55-220
8031.
0020-1693/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0020-1693(99)00015-8

102
G. Manzoni de Oli6eira et al. / Inorganica Chimica Acta 288 (1999) 101–105
These results inspired our new attempts to make
feasible the stabilization of the species
in the coordination sphere of the manganese atom,
using new reagents in the substitution of the complexes
X(CO)4MnPPh2SiMe3 [15] (X=Cl, Br, I).
We report the synthesis and characterization by means
of IR, 1H and 31P NMR of the new organometallic
complexes Cp%Mn(CO)2PPh2H (1), Cp%Mn(CO)2-
PPh2COCH3 (2), and Cp%Mn(CO)2PPh2S(O)2CH3 (3)
(Cp%=p-C5H4CH3). The first was obtained by photolytic
substitution of one CO ligand by the diphenylphosphane
ligand in Cp%Mn(CO)3 [16]. Complexes 2 and 3 were
obtained by reaction of 1 with CH3COCl (4) and
CH3S(O)2Cl (5), in the presence of triethylamine:
Scheme 1.
the phosphinic and sulfinic acids, respectively
[R2%P(O)]2O and [RS(O)]2O, could be isolated.
These results were the basis for new attempts [11] to
fix the extremely unstable sulfinylphosphinites (type V,
Scheme 1) in the coordination sphere of a complexed
metal atom, by the reactions of (CO)5M[P(C6H5)2H]
(M=Cr, Mo, W) with the organylsulfonyl chlorides
RSO2Cl (R=CH3, p-CH3C6H4) in triethylamine.
Stabilized type II isomers of sulfonylphosphane (type
I) were also expected. However it has been verified
experimentally that the sulfinylphosphinite complex ap-
pears only as an intermediary product, the decomposi-
tion of which leads to a diphosphoxane complex and
sulfinylsulfone (Scheme 2).
Et N
3
Cp%Mn(CO)2PPh2H+4, 5 “ Cp%Mn(CO)2PPh2L
THF
+Et3NH+Cl−
(L= –COCH3, –S(O)2CH3)
2. Experimental
Although the attempt had not been successful, the
reaction makes possible the preparation of diphosphox-
ane complexes in only one step, a procedure unknown
until now. Analog compounds of phosphor(V) in the
form of the unstable sulfinylphosphane oxide and sulfi-
nylphosphinates (types III and IV, respectively, Scheme
1) were detected by the same group [13,14].
The first results which signaled the real possibility
that occurrence of these stabilizations were obtained as
a result of reactions between the complex I(CO)4Mn-
PPh2SiMe3 (Ph=phenyl; Me=methyl) [15] and deriva-
tives of the carboxylic and sulfinic acids, respectively
(CF3CO)2O and RS(O)Cl (R=methyl, adamantyl), in
toluene at room temperature (r.t.) [12]. The first reac-
tion led to I(CO)4MnPPh2COCF3, an air-unstable com-
plex with good solubility in polar solvents. From the
reaction with methyl(adamantyl)sulfinyl chloride the
following products were isolated:
All manipulations were conducted under argon by
use of standard Schlenk techniques. The solvents were
dried with sodium/benzophenone and distilled before
use. CH3COCl was prepared from acetic acid and PCl3,
CH3S(O)2Cl was obtained by using the method of
Hearst [17], which refluxes methanesulfonic acid with
SOCl2. The complex P(C6H5)2H was prepared by hy-
drolysis of LiP(C6H5)2 [18], Cp%Mn(CO)3 was obtained
according to reported procedures [16,19].
IR spectra were recorded on a Brucker IFS 28 spec-
trophotometer, with wave number between 4000 and
400 cm−1. The films (KBr windows) were prepared
under argon, and measurements were made immedi-
ately after their preparation; the irradiation chamber
was maintained under an argon stream a few minutes
1
before, and during the measurements. H NMR spectra
were recorded on a Brucker DPX 200 spectrometer,
and chemical shifts are reported relative to internal
Me4Si. The solutions in anhydrous CDCl3 were pre-
pared under argon in Schlenk tubes. 31P NMR spectra
were recorded on a Brucker DPX 400 spectrometer
In this case, the occurrence of parallel reactions led
to a mixture of complexes, and the compounds above
could only be isolated by means of column chromatog-
raphy, but in insufficient amounts for a detailed spec-
troscopic investigation.
Scheme 2.

G. Manzoni de Oli6eira et al. / Inorganica Chimica Acta 288 (1999) 101–105
103
PPh2H, the 31P NMR spectrum shows a doublet at
−39.28 and −40.60 ppm, with JPH=214.7 Hz.
using H3PO4 (85%) as the external reference. The
samples were dissolved in anhydrous toluene under
argon.
2.2. (p5-Methylcyclopentadienyl)dicarbonylacetyl-
diphenylphosphane–manganese(I), Cp%Mn(CO)2PPh2-
COCH3 (2)
2.1. (p5-Methylcyclopentadienyl)dicarbonyl-diphenyl-
phosphinomanganese(I), Cp%Mn(CO)2PHPh2 (1)
In a 100-ml two-necked flask equipped with an
argon inlet and stirring bar, 2.07 g (5.5 mmol) of
complex 1 was dissolved in 50 ml of THF. A total of
0.63 g (6.22 mmol) of triethylamine was added slowly
under stirring, over a 20 min period. For 30 min 0.6
g (7.6 mmol) of acetyl chloride diluted in THF was
added dropwise to the orange solution, with
immediate precipitation of a large amount of a white
solid (triethylammonium chloride), in an exothermic
reaction. Simultaneously, the mixture turned pale
yellow. The reaction was filtered and the solvent was
In a 250-ml two-necked flask equipped with an argon
inlet and stirring bar, 2.45
g (11.2 mmol) of
Cp%Mn(CO)3 was dissolved in 100 ml of THF. The
yellow solution was irradiated with UV for 4.5 h under
stirring at 50°C and it turned slowly red. After libera-
tion of a stoichiometric amount of CO, 2.2 g (11.8
mmol) of diphenylphosphine was added dropwise and
after 0.5 h of stirring at r.t. the mixture turned yellow.
The solvent was removed under reduced pressure and
the yellow-oil residue was purified by high vacuum
fractionated distillation. Cp%Mn(CO)2PHPh2 separates
at 90°C under a pressure of 1×10−3 mbar. Yield, 62%
based on Cp%Mn(CO)3 taken. Properties: yellow oil,
air-unstable; C20H19MnPO2 (377.284).
removed under vacuum, giving
a
yellow–green
residue which was purified by column chroma-
tography over silica gel at −15°C, using a 2×20 cm
column (eluant, toluene). One single, wide stark-
orange zone contained the product. Properties:
yellow–green oil, very sensitive to air; C22H21MnPO3
(419.321).
IR (in KBr window): w(CO), 2017.9 s, 1912.9 s; P–H,
2285.3 (w, m), 888.6 (l, m); CH3, 2975.5 (was, m), 2903.4
(ws, m), 1461.3 (las, m), 1362.9 (ls, m), 928.2 (las, m);
CꢀH, CꢁC Ph rings, (l, v) 1572.5–695.5; C–H Ph
rings, (ws,as, v) 3100–3050 [20]; Cp–H, 3090.3 (w, m),
1032.5 (l, m), 830.6 (l, m); CꢁC Cp ring, 1480.3 (w, s),
1067.6 (w, s), 669.5 (las, m), 639.3 (ls, s); P–Ph, 1067.6
(w, s). The Mn–P stretching occurs at low frequency
(between 300 and 200 cm−1) [21] and cannot be de-
tected in the spectral region in which the measurements
were carried out (4000–400 cm−1). The IR spectrum of
Cp%Mn(CO)3 shows the two intensive w(CO) bands
(2025 and 1910 cm−1) expected for the C36 local sym-
metry of the M(CO)3 group. No bands were observed
in the region of absorption of the P–H group. 1H
NMR (200 MHz, CDCl3): l 1.95 (s, 3H, CH3–Cp);
6.02, 4.72 (d, 1H, P–H), JPH=260.2 Hz, agrees with
reported values for the PH coupling in compounds of
phosphorus with a coordination number 4 [15,22]; 4.59,
IR (in KBr window): the basic structure of
complex 1 remains unaltered, with the exception of
the absorptions of the P–H group, which cannot be
observed in the IR spectrum of 2. The band at 1670.7
cm−1 (s) which corresponds to the stretching of the
acetyl CO, and the modification of the bands
corresponding to the stretchings and bendings of the
methyl group are very important for the structural
definition. 1H NMR (200 MHz, CDCl3): l 1.94 (s,
3H, CH3–Cp), 2.23, 2.20 (d, 3H, –PPh2COCH3),
3JPCCH=6.0 Hz, comparison with data of the free
ligand is only possible with respect to the known
trifluoroacetylphosphane [25], with 3JPCCF=16 Hz;
4.59, 4.54 (d, 4H, CH3–C5H4). 7.69–7.17 (m, 10H,
Ph groups). There was no occurrence of resonances
of the PH proton. 31P NMR (400 MHz, toluene):
17.69 (s, –PPh2COCH3), due to the amplitude of the
3
4.55 (d, 4H, CH3–C5H4), JPMnCH=8.9 Hz [15]; 7.5–
3
31P NMR scale a signal from the JPCCH coupling, in
7.2 (m, 10H, Ph groups). For the free ligand
PH(C6H5)2, l 5.77, 4.68 (d, 1H, PH), JPH=218.3 Hz.
31P NMR (400 MHz, toluene): 73.68–71.63 (m, PH),
the two basic lines of the complex ‘doublet’ indicate a
the order of 6 Hz, should not be separated. For the
complex IMn(CO)4PPH2COCF3 of Lorenz et al. [12]
the PCCF coupling was not reported, and the singlet
of the phosphorus nucleus appears in the 31P{1H}
NMR spectrum at l=60.2 ppm, a value which seems
to corroborate our result above.
J
PH=331.7 Hz, a result which is in conflict with the
1
value for JPH in the H NMR measurements discussed
above (260.2 Hz). Due to the reciprocity of the P–H
coupling the values for JPH should not be discordant in
1H and 31P NMR measurements. In the 31P NMR
literature JPH values for tetra-coordinated phosphorus
are situated between 250 and 730 Hz [12] and 254 and
330 Hz [15]. Nevertheless it is known that complexes
represent special cases [22–24] with respect to the
chemical shift and to the JPH values. For the free ligand
2.3. (p5-Methylcyclopentadienyl)dicarbonylmethane-
sulfonyldiphenylphosphaneꢀmanganese(I),
Cp%Mn(CO)2PPh2S(O)2CH3 (3)
The preparation of complex 3 was carried out as
above using 1.72 g (4.57 mmol) of complex 1, 0.54 g

104
G. Manzoni de Oli6eira et al. / Inorganica Chimica Acta 288 (1999) 101–105
(5.33 mmol) of triethylamine and 0.57 g (5 mmol) of
CH3SO2Cl. Due to the impossibility of purification by
chromatography (instantaneous decomposition over the
column), excess reagents cannot be added. The mixture
was filtered and the solvent removed under vacuum.
Complex 3 was carefully isolated from the small excess
of reagents under high vacuum. A prolonged vacuum
must be avoided. Properties: red oil, instantaneous
decomposition in contact with air; C21H21MnPO4S
(455.369).
IR (in KBr window): the same bands corresponding
to the basic structure of complex 1 are present, with the
exception of the PH bands. Modification of the bands
corresponding to the stretchings and bendings of the
CH3 groups is also observed. The bands corresponding
to the asymmetric and symmetric stretching of the SO2
sulfonyl group appear at 1312.8 (m) and 1116.7 cm−1
Fig. 2. Probable structures of Cp%Mn(CO)2PPh2COCH3 (2) and
Cp%Mn(CO)2PPh2S(O)2CH3 (3).
The reaction of complex 1 with CH3COCl in the
presence of triethylamine occurs simultaneously with
the heterogeneous rupture of the P–H bond on the
diphenylphosphine ligand and displacement of the chlo-
ride ion in CH3COCl, under formation of the salt
Et3NH+Cl− and complex 2, the latter by electrophilic
attack of the ion [CH3CO]+ on the ligand ion
[(C6H5)2P]−. An identical electrophilic substitution
pathway can be formulated for the reaction of 1 with
CH3S(O)2Cl/triethylamine to yield 3. IR spectra of the
white solid formed during the reactions of complex 1 to
give complexes 2 and 3, were compared with the spec-
trum of triethylammonium chloride standard. It was
confirmed that these spectra are exactly alike: in addi-
tion to the bands corresponding to the stretchings and
bendings of the methyl and methylene groups, the
spectra also showed the intensive bands characteristic
of the R3NH+ vibrations of the aliphatic ammonium
salts between 2760 and 2250 cm−1. Fig. 2 shows the
structures of 2 and 3.
1
(w), respectively. H NMR (200 MHz, CDCl3): l 1.96
(s, 3H, CH3–Cp); 2.35 (s, 3H, –PPh2S(O)2CH3), the
relative areas of the two singlets show a relation of 1:1.
In the 1H NMR spectrum of the sulfinyl complex
IMn(CO)4PPh2S(O)CH3 [12] only a singlet occurs for
the methyl group at 2.7 ppm, also without PSCH
3
coupling; 4.63, 4.56 (d, 4H, CH3–C5H4), JPMnCH
=
10.4 Hz; 7.50–7.18 (m, 10H, Ph rings). 31P NMR (400
MHz, toluene): 32.33 (s, –PPh2S(O)2CH3) agrees with
reported l values for sulfur compounds of phosphorus
with coordination number 4 [12,22].
3. Results and discussion
Due to their physical characteristics the synthesized
complexes cannot be investigated by means of X-ray
diffractometry. The results of the elemental analyses are
not included because of the discord between calculated
and measured values, presumably as a consequence of
the high instability of the compounds. The spectro-
scopic data discussed above allow us to conclude that
the structures of 1, 2 and 3 are probably derived from
the structure of Cp%Mn(CO)3: the substitution of one
carbonyl for the diphenylphosphine ligand leads to the
formation of 1, whose structure is represented in Fig. 1.
For complex 3 the formation of the sulfinylphos-
phinite complex analog to type II of Scheme 1 (sulfi-
nylphosphinites) must also be considered:
However, due to the instability of the atomic aggre-
gate R2P–O–S(O)R%, these compounds have not yet
been characterized by IR spectroscopy, and data on
absorption bands of the P–O–S(O)R group are nonex-
istent. Even reports concerning absorption values for
the O–S(O) group are rare, and the available data for
the O–S(O)R group are specific for representative
compounds. Nevertheless, it is possible to associate
the related [20,21,26] absorptions of the S–O and
O–S(O)R groups with some bands situated in the
region between 1300 and 900 cm−1 of the IR spectrum
of 3. However, this ordination cannot be conclusive due
to the wide embracing area of the reported absorption
values. Finally, it must be added that 1, 2 and 3
represent the first compounds of their classes, in which
the species acetylphosphane and methanesulfonylphos-
Fig. 1. Probable structure of Cp%Mn(CO)2PHPh2 (1).

G. Manzoni de Oli6eira et al. / Inorganica Chimica Acta 288 (1999) 101–105
105
[9] B.A. Arbusov, Pure Appl. Chem. 9 (1964) 307; Z. Chem. 14
(1974) 41.
[10] A.K. Bhattacharya, G. Thyagarajan, Chem. Rev. 81 (1981) 415.
[11] C. Zeiher, J. Mohyla, I.-P. Lorenz, W. Hiller, J. Organomet.
Chem. 286 (1985) 159.
[12] G. Effinger, I.-P. Lorenz, Phosphorus, Sulfur Silicon 47 (1990)
335.
[13] I.-P. Lorenz, J.K. Thekumparampil, C. Zeiher, Inorg. Chim.
Acta 79b (1983) 197.
[14] J.K. Thekumparampil, Dr. rer. nat.–Thesis, Eberhard-Karls-
Universita¨t, Tu¨bingen, Germany, 1980.
[15] G. Effinger, W. Hiller, I.-P. Lorenz, Z. Naturforsch., Teil B 42
(1987) 1315.
[16] E.O. Fischer, R. Jira, Z. Naturforsch., Teil B 9 (1954) 618.
[17] P.J. Hearst, C.R. Noller, Organic Syntheses, vol. 4, Wiley, New
York, 1967.
[18] R. Appel, K. Geisler, J. Organomet. Chem. 112 (1976) 61.
[19] H. Brunner, W.A. Herrmann, Anorganisch-Chemisches Prak-
tikum fu¨r Fortgeschrittene—Metalorganische Chemie, Universi-
ta¨t Regensburg, 1979.
phane could be stabilized as ligands on the coordina-
tion sphere of a metal atom. Analog reactions with the
complex BrMn(CO)4PHPh2 led equally to compounds
which should be structurally equivalent to 2 and 3.
These reactions, however, do not proceed with the same
velocity and the products are extremely unstable, which
indicates that the stability of the P–R bond (R=acetyl,
sulfonyl) also depends on the molecular structure of the
parent complex. Reactions with Cp%Mn(CO)2PHPh2 oc-
cur faster and the products are relatively more stable
than those formed from the reactions with BrMn-
(CO)4PHPh2. This seems to reflect the stereochemical
preference of complex 1 to undergo substitution reac-
tions, possibly as a consequence of the electronic syner-
gism of the p-Cp%–Mn bond.
[20] N.B. Colthup, L.H. Daly, S.E. Wiberley, Introduction to In-
frared and Raman Spectroscopy, 3rd ed., Academic Press, San
Diego, 1990.
References
[1] A.J. Pearson, in: Organoiron Compounds in Stoichiometric Or-
ganic Synthesis, Comprehensive Organometallic Chemistry, 8
(1980) 939.
[2] G.F. Emerson, L. Watts, R. Pettit, J. Am. Chem. Soc. 87 (1965)
132.
[21] K. Nakamoto, Infrared and Raman Spectra of Inorganic and
Coordination Compounds, 4th ed., Wiley, New York, 1986.
[22] Work group of Professor Dr. I.-P. Lorenz, 31P-NMR Spek-
troskopie, Institut fu¨r Anorganische Chemie, Universita¨t
Mu¨nchen, Germany, 1994.
[3] K. Ehrlich, G.F. Emerson, J. Am. Chem. Soc. 94 (1972) 2464.
[4] W.A. Sheppard, J. Dickmann, J. Am. Chem. Soc. 86 (1964)
19893.
[5] F.A. Cotton, G. Wilkinson, Advanced Inorganic Chemistry,
Wiley, New York, 1988.
[23] G. Gorenstein, Phosphorus-31 NMR—Principles and Applica-
tions, Academic Press, San Diego, 1984.
[24] J.H. Letcher, J.R. Van Wazer, Top. Phosphorus Chem. 5 (1967)
75.
[25] E. Lindner, H.-D. Ebert, H. Lesiecki, G. Vordermeier, Angew.
Chem. 89 (1977) 276; Angew. Chem., Int. Ed. Engl. 16 (1977)
269.
[6] H. Kunzek, M. Braun, E. Nesener, K. Ru¨hlmann, J. Organomet.
Chem. 49 (1973) 149.
[7] Y. Segal, E. Casida, Tetrahedron Lett. 23 (1982) 139.
[8] E. Sinn, E. Naumann, Z. Chem. 6 (1986) 338.
[26] L.C. Thomas, Interpretation of the Infrared Spectra of
Organophosphorus Compounds, Heyden, London, 1974.
.