Base induced P-C bond cleavage in a coordinated bis(dimethylphosphino)methane ligand

Article abstract of DOI:10.1039/b607839g

Treatment of fac-[Mn(CNR)(CO)₃((PMe₂) ₂CH₂)]ClO₄ (1a R = Ph, 1b R = ^tBu) with KOH produced the cleavage of one of the P-C bonds of the coordinated dmpm ligand, resulting in the formation of phosphine-phosphinite complexes fac-[Mn(PMe₂O)(CNR)(CO)₃(PMe₃)] (2a,b). Alkoxides such as NaOMe and NaOEt promoted similar processes in 1a,b, yielding fac-[Mn(CNR)(CO)₃(PMe₃)(PMe₂OR′)]ClO ₄ (3a R = ^tBu, R′ = Me; 3b R = Ph, R′ = Me; 4a R = ^tBu, R′ = Et; 4b R = Ph, R′ = Et) derivatives. The phosphinite ligand in 2a,b can be sequentially protonated by addition of 0. 5 and 1 equivalent of HBF₄ leading to fac-[(Mn(CNR)(CO) ₃(PMe₃)(PMe₂O))₂H]BF₄ (6a,b) and fac-[Mn(CNR)(CO)₃(PMe₃)(PMe ₂OH)]BF₄ (5a,b), respectively. The Royal Society of Chemistry 2006.

Full text of DOI:10.1039/b607839g

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PAPER
www.rsc.org/dalton | Dalton Transactions
Base induced P–C bond cleavage in a coordinated
bis(dimethylphosphino)methane ligand
Javier Ruiz,*a Santiago Garc´ıa-Granda,b M. Rosario D´ıazb and Roberto Quesada*†a
Received 2nd June 2006, Accepted 19th July 2006
First published as an Advance Article on the web 2nd August 2006
DOI: 10.1039/b607839g
t
Treatment of fac-[Mn(CNR)(CO)3{(PMe2)2CH2}]ClO4 (1a R = Ph, 1b R = Bu) with KOH produced
the cleavage of one of the P–C bonds of the coordinated dmpm ligand, resulting in the formation of
phosphine–phosphinite complexes fac-[Mn(PMe2O)(CNR)(CO)3(PMe3)] (2a,b). Alkoxides such as
NaOMe and NaOEt promoted similar processes in 1a,b, yielding fac-[Mn(CNR)(CO)3(PMe3)-
t
t
(PMe2ORꢀ)]ClO4 (3a R = Bu, Rꢀ = Me; 3b R = Ph, Rꢀ = Me; 4a R = Bu, Rꢀ = Et; 4b R = Ph, Rꢀ = Et)
derivatives. The phosphinite ligand in 2a,b can be sequentially protonated by addition of 0.5 and 1
equivalent of HBF4 leading to fac-[{Mn(CNR)(CO)3(PMe3)(PMe2O)}2H]BF4 (6a,b) and
fac-[Mn(CNR)(CO)3(PMe3)(PMe2OH)]BF4 (5a,b), respectively.
but activation of a P–C bond of the ligand. A preliminary
communication of this work has been published.8
Introduction
Complexes bearing tertiary phosphine ligands play a central role in
homogeneous catalysis,1 and the understanding of the deactivation
pathways of these compounds is therefore of crucial importance.
P–C bond cleavage processes on coordinated phosphine ligands
are recognised among the side reactions resulting in the deactiva-
tion of this type of catalyst.2 Although not common, there are a
number of reported examples of this type of reaction in the litera-
ture, for example thermally induced rearrangements on phosphine
ligands coordinated to metal clusters, which usually lead to the
formation of P–M and M–C bonds.3 Pregosin and co-workers have
described several examples of P–C bond activation processes in
Binap and MeOBiphep biarylbis(phosphine) complexes of Ru(II)
promoted by the addition of acids.4 Nucleophilic additions can
also trigger these processes, especially in the case of functionalized
phosphines, and examples of P–C bond activation by alcohols have
been described.5 The vast majority of reported examples involve P–
Csp2 bonds, reflecting the widespread use of aryl phosphine ligands
and the higher reactivity of the P–Csp2 against the P–Csp3 bonds.2
Very recently, Grohmann and co-workers have published the P–C
bond breaking in an alkylphosphine iron complex promoted by
methanol.6
Results and discussion
Reaction of fac-[Mn(CNR)(CO)3dmpm]ClO4 (1a R = Ph; 1b R =
tBu)9 with an excess of KOH in CH2Cl2 produced, after 2 h of
stirring at room temperature, the neutral phosphinite complex
t
fac-[Mn(PMe2O)(CNR)(CO)3(PMe3)] (2a R = Bu; 2b R = Ph) in
good yields as a result of the cleavage of the diphosphine ligand. A
mechanism for this process is proposed in Scheme 1. Nucleophilic
attack of the OH− anion at a phosphorus atom would lead to
a transient complex containing dimethylphosphinous acid and
dimethylphosphinomethanide ligands, followed by intramolecular
proton transfer from oxygen to carbon.
We have extensively studied the chemistry of bis(di-
phenylphosphino)methanide complexes.7 These derivatives are
obtained by deprotonation of the central carbon atom of the
diphosphine ligand upon basic treatment. We decided to in-
vestigate other alkyldiphosphine ligands and herein we report
the reactivity of bis(dimethylphosphino)mehane manganese(I)
complexes towards bases, which do not lead to neat deprotonation
aDepartamento de Qu´ımica Orga´nica e Inorga´nica, Facultad de Qu´ımica,
Universidad de Oviedo, 33071 Oviedo, Spain. E-mail: jruiz@fq.uniovi.es;
Fax: +34 985103446
Scheme 1 Synthesis of compounds 2a,b.
As we highlighted in the Introduction, this result
contrasted with the reactivity displayed by the related
bis(diphenylphosphino)methane complex which led exclusively to
deprotonation of the central carbon atom upon treatment with
KOH. It is of note that, under quite harsh conditions, it has
bDepartamento de Qu´ımica F´ısica y Anal´ıtica, Facultad de Qu´ımica,
Universidad de Oviedo, 33071 Oviedo, Spain
† Current address: Departamento de Qu´ımica Orga´nica, Facultad de
Ciencias, Universidad Auto´noma de Madrid, 28049 Cantoblanco, Spain.
E-mail: roberto.quesada@uam.es
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Table 1 Selected spectroscopic data for compounds 1–6a,b
1
Compound
IRa m(CN + CO)/cm−1
31P{ H} NMRb d
1a
1b
2a
2b
3a
3b
4a
4b
5a
5b
6a
6b
2170 (m) 2037 (vs) 1977 (s)
2150 (m) 2037 (vs) 1977 (s)
2155 (m) 2010 (vs) 1945 (s)
2130 (m) 2009 (vs) 1937 (s)
2173 (m) 2041 (vs) 1976 (s)
2155 (m) 2041 (vs) 1981 (s)
2173 (m) 2042 (vs) 1976 (s)
2154 (m) 2041 (vs) 1981 (s)
2175 (m) 2037 (vs) 1971 (s)
2155 (m) 2037 (vs) 19 76 (s)
2166 (m) 2027 (vs) 1959 (s)
2146 (m) 2028 (vs) 19 66 (s)
−2.5
−2.0
80.0 (s, br) 12.5 (s, br)
80.2 (s, br) 12.5 (s, br)
155.1 (s, br) 10.0 (s, br)
155.0 (s, br) 10.1 (s, br)
155.3 (s, br) 11.1 (s, br)
152.0 (s, br) 8.0 (s, br)
139.8 (s, br) 10.1 (s, br)
140.0 (s, br) 10.2 (s, br)
112.1 (s, br) 12.0 (s, br)
111.3 (s, br) 11.2 (s, br)
a CH2Cl2. b CD2Cl2.
been reported the cleavage of the dppm ligand in [PtCl2dppm] by
basictreatment, leadingtodifferentpolynuclearspeciescontaining
phosphinite ligands.10 We have demonstrated the existence of
the deprotonation process in the treatment of 1a,b with KOH,
leading to very unstable diphosphinomethanide complexes which
are extremely sensitive to protonation by traces of moisture. These
derivatives can be trapped by carrying out the reaction in the
presence of electrophiles in the reaction media, or employing other
non-nucleophilic bases such as LDA.8
Fig. 1 ORTEP drawing of compound 2a showing the atom numbering
scheme. Thermal ellipsoids are drawn at 30% probability level. Hydrogen
atoms are omitted for clarity.
The neutral character of complexes 2a,b is reflected in the lower
frequencies for the C≡N and C≡O stretching band appearing in
the IR spectra with respect to the starting materials (Table 1). The
31P NMR spectrum reflected the cleavage of the diphosphine ligand
and displayed two signals at 80 and 12.5 ppm corresponding to the
dimethylphosphinite and trimethylphosphine ligands, respectively.
The new phosphinite complexes are chiral, and the 13C NMR
spectrum showed signals for each methyl group of dimethylphos-
phinite ligand in 2b (d 29.6, 2JP–C = 27 Hz; d 29.9, 2JP–C = 27 Hz)
in accordance with their diastereotropic character, although in the
case of 2a this signal is not resolved, appearing as a broad peak
centred at 29.7 ppm.
Fig. 2 Ball and stick representation of the hydrogen bonded adduct
formed by 2a and two water molecules in the solid state. Hydrogen atoms
are omitted for clarity.
O(5)–H(51)–O(1ꢀ) 167.50◦). The presence of water molecules
=
acting as hydrogen bond donors is not surprising since the P O
group is recognised as a good hydrogen bond acceptor.12 The
above hydrogen bonds can be regarded as incipient proton transfer
reactions, so it is anticipated that protic acids stronger than water
could produce the corresponding phosphinous acid as a stable
ligand, as we will see below.
The structure of complex 2a was determined by X-ray crystal-
lography. Two molecules of 2a were found in the asymmetric unit
featuring very similar structural parameters. The manganese atom
displays a slightly distorted octahedral coordination geometry
(Fig. 1). A selection of bond lengths and angles for this complex
is shown in Table 2. The complex crystallised jointly with two
water molecules, which are found bridging two complexes through
hydrogen bonds with the oxygen atoms of the phosphinite ligands
(Fig. 2). The structural parameters within the hydrogen bond
interactions allow them to be classified as moderate11 (O(1)–O(6)
We decided to test whether other bases such as alkox-
ides promoted similar cleavage processes on the coordinated
diphosphine ligand. Treatment of 1a,b with NaOMe/MeOH or
NaOEt/EtOH in CH2Cl2 yielded the cationic derivatives fac-
t
[Mn(CNR)(CO)3(PMe3)(PMe2ORꢀ)]ClO4 (3a R = Bu, Rꢀ = Me;
ꢀ
ꢀ
t
3b R = Ph, Rꢀ = Me; 4a R = Bu, Rꢀ = Et; 4b R = Ph,
˚
˚
˚
˚
2.747 A, O(1 )–O(6) 2.878 A, O(1)–O(5) 2.9777 A, O(1 )–O(6)
◦
◦
ꢀ
Rꢀ = Et). In this case, nucleophilic attack of the (ORꢀ)− group
at the phosphorus atom produced an intermediate containing
a PMe2ORꢀ group and an anionic ligand (PMe2CH2)− which
is immediately protonated by an alcohol molecule to yield the
observed products (Scheme 2). Overall, this process resembles the
formal addition of an alcohol molecule (RꢀOH) over a P–C bond
of the ligand. Nevertheless, the alcohol with catalytic amounts of
alkoxide do not promote the cleavage of the P–C bond even under
forcing conditions.
2.820 A, O(6)–H(61)–O(1) 161.52 , O(6)–H(62)–O(1 ) 147.48 ,
◦
˚
Table 2 Selected bond lengths [A] and angles ( ) for 2a
Mn(1)–P(1)
Mn(1)–P(2)
P(1)–C(1)
P(1)–C(2)
P(1)–C(3)
P(2)–O(1)
P(2)–C(5)
P(2)–C(4)
2.325(4)
2.353(5)
1.812(5)
1.806(4)
1.819(5)
1.522(3)
1.821(5)
1.823(5)
P(1)–Mn(1)–P(2)
O(1)–P(2)–C(4)
O(1)–P(2)–C(5)
C(4)–P(2)–C(5)
C(2)–P(1)–C(1)
C(2)–P(1)–C(3)
C(1)–P(1)–C(3)
89.51(11)
106.9(2)
107.4(5)
101.0(3)
103.4(3)
103.4(3)
101.4(3)
Spectroscopic data are in agreement with the proposed for-
mulation for these derivatives. IR spectrum showed the mCN and
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Interestingly, we found that another intermediate species
could be detected by IR spectroscopy when the protonation
process was not completed. These intermediates were ob-
tained by addition of half equivalent of HBF4 to 2a,b solu-
tions and tentatively identified as the dinuclear aggregates fac-
t
[{Mn(CNR)(CO)3(PMe3)(PMe2O)}2H]BF4 (6a R = Bu, 6b R =
Ph), in which the proton is bridging two phosphinite ligands. These
species seem to arise from the reaction of a coordinated phosphi-
nous acid and phosphinite ligands. Indeed, they are also cleanly
obtained when mixing equimolar amounts of the neutral 2a,b and
cationic 5a,b derivatives in solution. All these reactions are readily
reversible by treatment with KOH (Scheme 4). The chelating
Scheme 2 Synthesis of compounds 3–4a,b.
−
ligand {R2P–O · · · H · · · O–PR2} , is frequently described in the
mCO bands at similar frequencies to those corresponding to the
literature, within complexes bearing phosphinite and phosphinous
acid ligands in cis positions on the coordination sphere of the
metal center.16 On the other hand, to the best of our knowledge,
there is only one reported example of a structurally characterized
compound with a similar ligand bridging two different metallic
fragments.17 The solid state structure of the neutral complex 2a,
with water molecules bridging two phosphinite ligands, heralded
the feasibility of the formation of similar bridged species upon
protonation.
starting materials, characteristic of this type of cationic derivative.
31P{ H} spectrum displayed two signals corresponding to the two
1
inequivalent phosphorus atoms of the molecule. The chemical shift
of the trimethylphosphine ligand is very similar to that found in
2a,b, meanwhile alkylation of the phosphinite ligand resulted in a
dramatic downfield shift of the chemical shift corresponding to this
phosphorus atom to 152–155 ppm. Finally, the 1H NMR spectrum
showed characteristic signals for the methylene and methyl groups
of the phosphinite ligand. Alternatively, compounds 3a,b can be
prepared by methylation of the neutral phosphinite complexes 2a,b
with MeI (Scheme 3).
Scheme 3 Methylation of compounds 2a,b.
The synthesis and coordination chemistry of phosphinite lig-
ands have been studied,13 and some of these compounds have been
successfully employed in different catalytic processes.14 Recently,
neutral Pd(II) complexes with simple phosphinous acid ligands
have been reported to be efficient catalysts precursors for C–C,
C–N and C–S bond formation reactions of aryl chlorides under
basic conditions.15 This suggest that anionic phosphinite species
might act as the true catalysts; the protonation behaviour being a
key step of their role in these processes. All these reports prompted
us to explore the reactivity of 2a,b toward acids.
Scheme 4 Protonation reactions of compounds 2a,b.
1
Both IR and 31P{ H} spectra reflected the proposed structure for
6a,b, with a symmetrical bridge in solution. Thus mCO and mCN fre-
quencies and the chemical shift of the phosphinite–phosphinous
acid ligands appeared at intermediate values between the neutral
2a,b and the protonated 5a,b species (Table 1). Moreover, IR
spectra recorded in a nujol dispersion of 6a,b showed the lack
of the characteristic O–H band, as the vibrations ascribed to the
O · · · H · · · O system appear below 2000 cm−1.18
The phosphinite ligand in 2a,b can be protonated by
treatment with HBF4 to yield the cationic derivatives fac-
t
[Mn(CNR)(CO)3(PMe3)(PMe2OH)]BF4 (5a R = Bu, 5b R =
A titration experiment with increasing amounts of HBF4 shed
light on the acid–base behaviour of this ligand in solution. Only
Ph). Spectroscopic data reflected the changes upon protonation,
thus the IR spectra corresponded to cationic derivatives with mCO
and mCN bands appearing at higher frequencies than the neutral
phosphinite complexes 2a,b. Moreover, IR spectra recorded in
a Nujol dispersion of 6a,b showed a characteristic band at
1
two signals appeared in the 31P{ H} NMR spectra during all the
experiment. The chemical shifts of this signal drifted between the
values observed for the neutral 2a,b and cationic 5a,b complexes as
function of the quantity of HBF4 added. This seems to indicate the
existence of a fast proton transfer process in the NMR timescale
between the phosphinite and phosphinous acid ligands and the
chemical shift corresponding to these signals are an average value
of the different species present in solution (Fig. 3). On the other
hand, the IR spectroscopy allows us to follow the sequential
1
3250 cm−1 assignable to the O–H group. 31P{ H} spectrum showed
almost no variation in the chemical shift corresponding to the
trimethylphosphine ligand along with a dramatic downfield shift
for the signal corresponding to the dimethylphosphinous ligand
to 140 ppm as a result of the protonation of the oxygen atom.
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dichloromethane and 0.18 mL (1.6 mmol) of CNtBu were added.
After 12 h stirring, the solvent was removed under vacuum and
the residue washed with hexane (3 × 10 mL) and diethyl ether
(2 × 10 mL) to remove excess isocyanate, yielding a white solid
(yield 311 mg, 85%). Elemental analysis (%) found: C, 34.0; H,
4.7; N, 3.2. calcd for C13H23ClMnNO7P2: C, 34.1; H, 5.1; N, 3.1%;
IR (CH2Cl2) m/cm−1 : 2170 m (CNtBu), 2037 vs, 1971 s (CO); 1H
NMR (CDCl3): d = 3.98 (1H, dt, 2JHH = 16, 2JPH = 11, P2CH2),
3.54 (1H, dt, 2JHH = 16, 2JPH = 11, P2CH2), 1.83 (12H, m, P(CH3)2),
1.66 (9H, s, C(CH3)3); 31P{ H} NMR (CDCl3): d = −2.5.
1
1
Fig. 3 Stack plot of the 31P{ H} NMR spectra of compound 2a in the
fac-[Mn(CNPh)(CO)3(dmpm)]ClO4 1b. This compound was
prepared similarly to 1a employing 165 mg (1.60 mmol) of CNPh
and 200 mg (0.80 mmol) of fac-[Mn(OClO3)(CO)3(dmpm)] (yield
321 mg, 84%). Elemental analysis (%) found: C, 37.4; H, 4.2; N,
3.1. calcd for C15H19ClMnNO7P2: C, 37.8; H, 4.0; N, 2.9%; IR
presence of increasing amounts of HBF4 (0–1 equivalent) recorded in
CD2Cl2.
conversion of the different species 2a,b → 6a,b → 5a,b as a
function of the amount of HBF4 added.
(CH2Cl2) m/cm−1 : 2150 m (CNPh), 2037 vs, 1977 s (CO); H
1
NMR (CDCl3): d = 7.54 (5H, br), 3.85 (1H, dt, 2JHH = 19, 2JPH
=
Conclusions
12, P2CH2), 3.56 (1H, dt, 2JHH = 19, 2JPH = 12, P2CH2), 1.86 (12H,
1
m, P(CH3)2); 31P{ H} NMR (CDCl3): d = −2.0.
We have demonstrated that coordinated bis(dimethyl-
phosphino)methane ligand undergo P–C cleavage processes by
treatment with KOH and alkoxides under very mild conditions.
This result represents an unprecedented example of reactivity
for this widely used ligand, and it is of interest when compared
with the reactivity of the related bis(diphenylphosphino)methane
complexes. These derivatives do not experience this type of
transformation upon similar basic treatments, even though
the arylphosphine ligands are considered to be more reactive
towards P–C activation than alkylphosphines. The cleavage
of the diphosphine ligand provides access to different chiral
phosphinite complexes. Finally, it is possible to protonate the
oxygen atom of the neutral phosphinite ligand by treatment
with 0.5 and 1 equivalents of HBF4 resulting in bridging
phosphinite–phosphinous acid and phosphinous acid ligands,
respectively.
fac-[Mn(PMe2O)(CNtBu)(CO)3(PMe3 )]
2a. 200
mg
(0.44 mmol) of 1a were dissolved in 20 mL of dichloromethane
and an excess of KOH (800 mg) was added. The mixture was
vigorously stirred for 1.5 h and then filtered. The volume was
reduced to approximately 5 mL under reduced pressure and
addition of 20 mL of hexane produced the precipitation of a white
solid which was filtered and dried (Yield 133 mg, 80%). X-Ray
quality crystals were grown by slow diffusion of diethyl ether into
a concentrated solution of this compound in dichloromethane.
Elemental analysis (%) found: C, 41.8; H, 6.8; N, 3.9. Calcd
for C13H24MnNO4P2: C, 41.6; H, 6.45; N, 3.7%; IR (CH2Cl2)
m/cm−1 : 2155 m (CNtBu), 2010 vs, 1945 s (CO); 1H NMR
(CD2Cl2): d = 1.71–1.60 (24H, m); 13C NMR (CD2Cl2): d = 219.0
(s, br, CO), 160.6 (CNC), 58.5 (C(CH3)3), 30.6(C(CH3)3), 29.7
1
1
(s, br, P(CH3)2O), 18.5 (d, JPC = 29, P(CH3)3); 31P{ H} NMR
(CD2Cl2): d = 80.2 (s, br), 12.5 (s, br).
Experimental
fac-[Mn(PMe2O)(CNPh)(CO)3(PMe3)] 2b. This compound
was prepared as above, starting with 200 mg (0.42 mmol) of
compound 1b (Yield 146 mg, 88%). Elemental analysis (%) found:
C, 45.4; H, 5.0; N, 3.5. Calcd for C15H20MnNO4P2: C, 45.6; H,
5.1; N, 3.5%; IR (CH2Cl2) m/cm−1 : 2130 m (CNPh), 2009 vs,
General
All reactions were carried out under a nitrogen atmosphere using
standard Schlenk techniques. Solvents were dried and purified
by standard techniques and distilled under nitrogen prior to use.
All reactions were monitored by IR spectroscopy (Perkin-Elmer
FT 1720-X and Paragon 1000 spectrophotometers). Elemental
analyses were performed on a Perkin-Elmer 240B elemental
analyser. 1H, 13C and 31P NMR spectra were recorded using
Bruker AC-300 and AC-200 instruments. Chemical shifts are given
in ppm relative to internal SiMe4 (1H) or external 85% H3PO4
(31P) references. Conductivity experiments were performed in a
Jenway PCM3 apparatus with 3–4 × 10−4 M acetone solutions
at room temperature. The values obtained were compared with
those reported in the literature.19 Manganese complexes fac-
1
1937 s (CO); H NMR (CD2Cl2): d = 7.46 (5H, br, Ph), 1.71–
1.60 (15H, m); 13C NMR (CD2Cl2): d = 219.2 (s, br, CO), 178.85
(CNC), 130.1–126.2 (Ph), 29.9 (d, 1JPC = 27, P(CH3)2O), 29.6 (d,
1
1JPC = 27, P(CH3)2O), 18.7 (d, 1JPC = 30, P(CH3)3); 31P{ H} NMR
(CD2Cl2): d = 80.2 (s, br), 12.5 (s, br).
fac-[Mn(CNtBu)(CO)3(PMe3)(PMe2OMe)]ClO4 3a. MeONa
(113 mg, 2.10 mmol) and 0.5 mL of MeOH were added to a
solution of 1a (200 mg, 0.44 mmol) in 20 mL of dichloromethane.
The mixture was vigorously stirred for 1.5 h, monitoring the
reaction by IR spectroscopy, and then filtered. The volume was
reduced to approximately 5 mL under reduced pressure and
addition of 20 mL of diethyl ether produced the precipitation
of a white solid which was filtered and dried (yield 147 mg, 68%).
Elemental analysis (%) found: C, 34.7; H, 5.9; N, 3.2. Calcd for
t
[Mn(CNR)(CO)3dmpm]ClO4 (1a R = Ph; 1b R = Bu) were
prepared as reported for the related dppm derivatives.9
Syntheses
C14H27ClMnNO8P2: C, 34.3; H, 5.6; N, 2.9%; IR (CH2Cl2) m/cm−1
:
1
fac-[Mn(CNtBu)(CO)3(dmpm)]ClO4 1a. 200 mg (0.80 mmol)
of fac-[Mn(OClO3)(CO)3(dmpm)] were dissolved in 30 mL of
2173 m (CNtBu), 2041 vs, 1976 s (CO); H NMR (CD2Cl2): d =
3
2
3.71 (3H, d, JPH = 12, OCH3), 1.98 (3H, d, JPH = 6, P(CH3)2),
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1.96 (3H, d, 2JPH = 6, P(CH3)2), 1.62 (9H, d, 2JPH = 10, P(CH3)3),
95 mg (0.25 mmol) of 2a dissolved in 10 mL of dichloromethane.
After 5 min stirring, solvents were removed by evaporation and
the residue obtained washed with diethyl ether (2 × 5 mL) yielding
a white solid (yield 94 mg, 90%). Elemental analysis (%) found:
C, 37.1; H, 5.8; N, 3.4. Calcd for C26H49BF4Mn2N2O8P4: C, 37.25;
H, 5.9; N, 3.3%; IR (CH2Cl2) m/cm−1 : 2166 m (CNtBu), 2027 vs,
1959 s (CO); 1H NMR (CD2Cl2): d = 1.73 (6H, m, P(CH3)2), 1.58
1
1.59 (9H, s, C(CH3)3); 31P{ H} NMR (CD2Cl2): d = 155.1 (s, br),
10.0 (s, br).
fac-[Mn(CNPh)(CO)3(PMe3)(PMe2OMe)]ClO4
3b. This
compound was prepared as above, starting with 200 mg
(0.42 mmol) of compound 1b (yield 149 mg, 70%). Elemental
analysis (%) found: C, 38.25; H, 5.0; N, 3.0. Calcd for
C16H23ClMnNO8P2: C, 37.7; H, 4.55; N, 2.75%; IR (CH2Cl2)
m/cm−1 : 2155 m (CNPh), 2041 vs, 1981 s (CO); 1H NMR
1
(9H, d, 2JPH = 9, P(CH3)3), 1.55 (9H, s, C(CH3)3); 31P{ H} NMR
(CD2Cl2): d = 112.1 (s, br), 12.0 (s, br); Ko (acetone) = 138 S
cm2 mol−1, [] = 3.3 × 10−4 M.
3
(CD2Cl2): d = 7.50 (5H, br, Ph), 3.75 (3H, d, JPH = 11, OCH3),
fac-[{Mn(CNPh)(CO)3(PMe3)(PMe2O)}2H)]BF4
6b. This
2.04 (6H, d, 2JPH = 6, P(CH3)2), 1.68 (9H, d, 2JPH = 9, P(CH3)3);
compound was prepared similarly to 6a, starting with 100 mg
(0.25 mmol) of 2b and 18 ll (0.13 mmol) of HBF4 (54% diethyl
ether complex) (Yield 99 mg, 90%). Elemental analysis (%) found:
C, 41.1; H, 4.4; N, 3.3. Calcd for C30H41BF4Mn2N2O8P4: C, 41.0;
H, 4.7; N, 3.2%; IR (CH2Cl2) m/cm−1 : 2146 m (CNtBu), 2028 vs,
1966 s (CO); 1H NMR (CD2Cl2): d = 7.51 (5H, br, Ph), 1.99 (3H,
1
31P{ H} NMR (CD2Cl2): d = 155.0 (s, br), 10.1 (s, br).
fac-[Mn(CNtBu)(CO)3(PMe3)(PMe2OEt)]ClO4 4a. This com-
pound was prepared similarly to 3a, adding 150 mg (2.2 mmol) of
EtONa and 0.5 mL of MeOH to 200 mg (0.44 mmol) of compound
1a (Yield 155 mg, 70%). Elemental analysis (%) found: C, 35.4; H,
5.3; N, 2.5. Calcd for C15H29ClMnNO8P2: C, 35.6; H, 5.8; N, 2.8%;
IR (CH2Cl2) m/cm−1 : 2173 m (CNtBu), 2042 vs, 1975 s (CO); 1H
NMR (CD2Cl2): d = 3.94 (2H, m, OCH2), 1.91 (3H, d, 2JPH = 10,
P(CH3)2), 1.89 (3H, d, 2JPH = 6, P(CH3)2), 1.58 (9H, d, 2JPH = 10,
P(CH3)3), 1.56 (9H, s, C(CH3)3), 1.31 (3H, t, 3JHH = 6, OCH2CH3);
2
2
d, JPH = 8, P(CH3)2O), 1.97 (3H, d, JPH = 8, P(CH3)2O), 1.67
(9H, d, 2JPH = 10, P(CH3)3); 31P{ H} NMR (CD2Cl2): d = 111.3
1
(s, br), 11.2 (s, br).
X-Ray crystallography
1
31P{ H} NMR (CD2Cl2): d = 155.3 (s, br), 11.1 (s, br).
Crystal data for 2a (C13H24MnNO4P2·H2O): M = 393.23, crystal
size 0.46 × 0.46 × 0.20 mm, a = 10.526(2), b = 14.56(1), c =
fac-[Mn(CNPh)(CO)3(PMe3)(PMe2OEt)]ClO4 4b. This com-
pound was prepared as above, starting with 200 mg (0.42 mmol) of
compound 1b (Yield 154 mg, 70%). Elemental analysis (%) found:
C, 38.6; H, 4.6; N, 2.45. Calcd for C17H25ClMnNO8P2: C, 39.0;
H, 4.8; N, 2.7%; IR (CH2Cl2) m/cm−1 : 2154 m (CNPh), 2041 vs,
1981 s (CO); 1H NMR (CD2Cl2): d = 7.54 (5H, br, Ph), 3.99 (2H,
◦
˚
˚
14.59(3) A, a = 108.43(8), b = 98.3(1), c = 98.58(7) , V =
2054(5) A , qcalcd = 1.272 g cm−3, l = 0.816 mm−1, Z = 4,
3
˚
triclinic, space group P1, k = 0.71073 A, T = 293(2) K, Hmax
=
25.97, independent reflections = 8009, refined parameters = 411,
R1 = 0.0438, wR2 = 0.1103, largest diff. peak and hole 0.50 and
−3
˚
m, OCH2), 1.99 (6H, d, 2JPH = 10, P(CH3)2), 1.67 (9H, d, 2JPH
=
−0.52 e A .
3
1
9, P(CH3)3), 1.33 (3H, t, JHH = 7, OCH2CH3); 31P{ H} NMR
CCDC reference number 210714.
For crystallographic data in CIF or other electronic format see
DOI: 10.1039/b607839g
(CD2Cl2): d = 152.0 (s, br), 8.0 (s, br).
fac-[Mn(CNtBu)(CO)3(PMe3)(PMe2OH)]BF4
5a. 37
ll
Two molecules of the complex were found in the asymmet-
ric unit. Both molecules have very similar structural parameters,
with differences arising from the presence of two molecules of
water displaying O–H · · · O hydrogen bonds with the oxygen atom
of the phosphinite ligand in one of them.
(0.27 mmol) of HBF4 (54% diethyl ether complex) were added to
100 mg (0.27 mmol) of 2a dissolved in 10 mL of dichloromethane.
Evaporation of solvents to approximately 2 mL followed by
addition of 20 mL of diethyl ether produced the precipitation
of a white solid which was collected and dried (yield 112 mg,
90%). Elemental analysis (%) found: C, 33.6; H, 5.4; N, 2.9.
calcd for C13H25BF4MnNO4P2: C, 33.7; H, 5.4; N, 3.0%; IR
Acknowledgements
1
(CH2Cl2) m/cm−1 : 2175 m (CNtBu), 2037 vs, 1971 s (CO); H
Financial support by the Spanish Ministerio de Ciencia y Tec-
nolog´ıa (PGE and FEDER funding, Project BQU2003–01011) is
gratefully acknowledged. R. Q. would like to thank the Ministerio
de Ciencia y Tecnolog´ıa for a Juan de la Cierva contract.
2
NMR (CD2Cl2): d = 1.93 (6H, m, P(CH3)2), 1.59 (9H, d, JPH
=
10, P(CH3)3), 1.56 (9H, s, C(CH3)3); 31P(CH3)3); 31P{ H} NMR
(CD2Cl2): d = 139.8 (s, br), 10.1 (s, br); Ko (acetone) = 132 S
cm2 mol−1, [] = 3.1 × 10−4 M.
1
References
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pound was prepared in the same manner as 5a, starting with
100 mg (0.25 mmol) of 2b and 34 ll (0.25 mmol) of HBF4 (54%
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Dalton Trans., 2006, 4371–4376 | 4375
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4376 | Dalton Trans., 2006, 4371–4376
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