Aryl(dimethylaminomethyl)phosphinic Acid Esters: Syntheses, Structures, and Reactions with Halogen Hydrogen Acids, Tin Halides, and Trimethyl Halosilanes

Article abstract of DOI:10.1002/ejic.201800343

This paper reports the synthesis of the aryl(iodomethyl)phosphinic acid ethyl esters, Ar(ICH₂)P(O)OEt (Ar = Ph, Ar = mesityl), which, via dimethyamination, are converted to the corresponding aryl(dimethylaminomethyl)phosphinic acid ethyl esters, Ar(Me₂NCH₂)P(O)OEt (Ar = Ph, Ar = mesityl). Upon reaction with hydrogen chloride, compound Me₂NCH₂(Ph)P(O)OEt forms its hydrochloride salt as a crystalline material. Depending on the reaction conditions, treatment of Me₂NCH₂(Ph)P(O)OEt with SnCl₂ gave either [Me₂HNCH₂(Ph)P(O)OEt][SnCl₃] or the mixed-valent dinuclear tin salt [{Me₂HNCH₂(Ph)P(O)O}₄SnCl₂][SnCl₃]₂, as its dichloromethane solvate. The reaction of Me₂NCH₂(Mes)P(O)OEt with SiMe₃I gives the diorgano bis(trimethylsiloxy)phosphinium iodide [Me₂NCH₂(Mes)P(OSiMe₃)₂]I, as its toluene solvate. In solution, it is involved in an equilibrium with Me₂NCH₂(Mes)P(O)OSiMe₃ and SiMe₃I. From the hydrolysis of [Me₂NCH₂(Mes)P(OSiMe₃)₂]I, the hydrogen iodide derivative [Me₂HNCH₂(Mes)P(O)OH]I was obtained as three different solvates. [Me₂NCH₂(Mes)P(OSiMe₃)₂]I reacted with SnF₂ to give a product mixture from which the mixed-valent tin compound [{Sn^II₂Me₂NCH₂(Mes)P(O)₂}₄Sn^IVF₂]I₂, was isolated. The compounds were characterized by NMR and IR spectroscopy, electrospray ionization mass spectrometry, and single-crystal X-ray diffraction analysis.

Full text of DOI:10.1002/ejic.201800343

A Journal of
Accepted Article
Title: Aryl(dimethylaminomethyl)phosphinic Acid Esters. Syntheses,
Structures, and Reactions with Halogen Hydrogen Acids, Tin
Halides and Trimethyl Halosilanes
Authors: Michael Lutter and Klaus Jurkschat
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To be cited as: Eur. J. Inorg. Chem. 10.1002/ejic.201800343
Link to VoR: http://dx.doi.org/10.1002/ejic.201800343

10.1002/ejic.201800343
European Journal of Inorganic Chemistry
FULL PAPER
Aryl(dimethylaminomethyl)phosphinic Acid Esters. Syntheses,
Structures, and Reactions with Halogen Hydrogen Acids, Tin Halides
and Trimethyl Halosilanes
Michael Lutter, Klaus Jurkschat*
Abstract:
This
paper
reports
the
synthesis
of
the
SiMe3Cl < SiMe3Br < SiMe3I.[3,4] In the case when trimethyl
chlorosilane is used, the addition of iodide salts accelerates the
reaction.[4,5] By the microwave-assisted silylation with
aryl(iodomethyl)phosphinic acid ethyl esters, Ar(ICH2)P(O)OEt (2a,
Ar = Ph; 2b, Ar = mesityl) which, via dimethyamination, are converted
to give the corresponding aryl(dimethylaminomethyl)phosphinic acid
ethyl esters, Ar(Me2NCH2)P(O)OEt (3a, Ar = Ph; 3b, Ar = mesityl).
Upon reaction with hydrogen chloride, compound 3a forms its
hydrochloride salt [3a·H]Cl as crystalline material. Depending on the
reaction conditions, treatment of 3a with SnCl2 gave either
trimethylbromosilane or with
a
mixture consisting of
trimethylchlorosilane and sodium iodide the reaction time can be
reduced to two minutes.[6] In addition to these methods, the
reaction with tin(II)chloride was also attempted.
To the best of our knowledge there is only one molecular structure
of a silylated phosphinic acid reported in the literature.[7] Solid
state structures of disilylated phophinium anions are not known at
all.[8]
Herein, we report the synthesis of the aryl(dimethylaminomethyl)
phosphinic acid ethyl ester Ar(Me2NCH2)P(O)OEt and show its
versatile reactivity towards halogen hydrogen acids, tin(II) halides,
and trimethyl halosilanes, giving rise to formation of hydrogen
halides, salts of different tin nuclearity, and an unprecedented
equilibrium involving a silylester and a phosphinium salt.
[3a·H][SnCl3]
or
the
mixed-valent
dinuclear
tin
salt
[{Me2HNCH2(Ph)P(O)O}4SnCl2][SnCl3]2, 4, as its dichloromethane
solvate 4·6CH2Cl2. The reaction of 3b with SiMe3I gave the diorgano
bis(trimethylsiloxy)phosphinium iodide [Me2NCH2(Mes)P(OSiMe3)2]I,
5, as its toluene solvate 5·0.5C7H8. In solution, it is involved in an
equilibrium with Me2NCH2(Mes)P(O)OSiMe3 and SiMe3I. From the
hydrolysis
of
5
the
hydrogen
iodide
derivative
[Me2HNCH2(Mes)P(O)OH]I, 6, as three different solvates 6·0.5 HI·0.5
CH3OH, 6·0.5HI and 6·HI·CH2Cl2, was obtained. Compound 5 reacted
with SnF2 to give a product mixture from which the mixed-valent tin
compound [{SnII Me2NCH2(Mes)P(O)2}4SnIVF2]I2, 7, was isolated. The
2
compounds were characterized by NMR and IR spectroscopy,
electrospray ionization mass spectrometry, and single crystal X-ray
diffraction analysis.
Results and Discussion
According to Scheme 1, the aryl(dimethylaminomethyl) phospinic
acid esters 3a and 3b, respectively, were prepared from
ArP(OEt)2 (a, Ar = Ph; b, Ar = Mesityl) following a modified
reaction sequence described by Khlebarov and co-workers.[9]
Introduction
Me2NH
Na2CO3
O
P
O
α-Aminoalkyl phosphinic acids are structural analogues of amino
acids and to date they are less investigated than α-aminoalkyl
phosphonic acids. This is somewhat surprising as α-aminoalkyl
phosphinic acids are more similar to amino acids since both have
one acidic proton. α-Aminoalkyl phosphinic acids are flame-
retardant and show biologic activity.[1,2]
CH2I2
P O
( Et)2
Ar
OEt
P OEt
Ar
Ar
 NaHCO3
 NaI
 EtI
I
NMe2
1a, Ar = Ph
1b, Ar = Mes
2a, Ar = Ph
2b, Ar = Mes
3a, Ar = Ph
3b, Ar = Mes
Scheme 1. Synthesis of the aryl(dimethylaminomethyl) phosphinic acid esters
3a and 3b.
A key step to obtain phosphinic acids is the de-alkylation of
phosphinic acid esters. On the other hand, aryl(-hydroxymethyl)
phosphinic acid was obtained from the reaction between aryl
phosphinic acid and acetone.[2] The reaction of phosphinic acid
esters with mineral acids at elevated temperature is a well
described de-alkylation method.[2] Another established and milder
approach to remove the ester group is the reaction with trimethyl
halosilanes and subsequent hydrolysis with methanol. The
reactivity of the trimethyl halosilanes increases in the order
The reaction of PhP(OEt)2 and MesP(OEt)2, respectively, with
diiodomethane in a Michaelis-Arbuzov reaction[10] gave the
corresponding aryl(iodomethyl) phosphinic acid ester 2,
Ar(ICH2)P(O)(OEt) (a, Ar = Ph; b, Ar = Mes), in good yields. Both
compounds show good solubility in common organic solvents
such as dichloromethane, diethyl ether, THF, ethyl acetate,
acetone, and hot iso-hexane. 31P{1H} NMR spectra (in CDCl3)
show for the phosphinic acid esters single resonances at δ 35.4
(2a) and δ 38.0 (2b), respectively. As expected, these signals are
high field shifted as compared to the resonances measured for
the phosphonites 1a (δ 157.0) and 1b (δ 177.5).[11] Compound
2b crystallized from its solution in diethyl ether as colourless
[*]
Lehrstuhl für Anorganische Chemie II, Technische Universität
Dortmund, Otto-Hahn-Straße 6, 44227 Dortmund, Germany, E-Mail:
klaus.jurkschat@tu-dortmund.de
Supporting information for this article is given via a link at the end of
the document.
ꢀ
blocks in the triclinic space group P1 with two molecules per unit
cell (Figure 1). To the best of our knowledge the latter represents
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10.1002/ejic.201800343
European Journal of Inorganic Chemistry
FULL PAPER
the first crystallographically determined structure of compounds
exhibiting the general formula R(XCH2)P(O)(OR’) (R = R’ = alkyl,
aryl; X = halogen). Figure 1 shows its molecular structure, as
determined by single crystal X-ray diffraction analysis. The figure
caption contains selected interatomic distances and angles.
Figure 2. Displacement ellipsoid (30% probability level) plot and numbering
scheme of the structure in the solid state of compound [3a·H]Cl. CH hydrogen
atoms and the disordered atoms are omitted. Hydrogen bond distances [Å]:
N(11)···Cl(1) 3.011(3), N(11)–H(11)···Cl(1) 2.12(2).
To obtain the phosphinic acids Ar(Me2NCH2)P(O)(OH) (Ar =
Ph, Mes) several reactions were attempted. The reaction of a
phosphinic acid ester with diluted hydrogen halides is a common
reaction to obtain the corresponding acid.[12] However, the
reactions of both the phosphinic acid ethyl esters 3a and 3b with
diluted or concentrated hydrogen halides (HCl, HBr, HI) at room
temperature or elevated temperatures exclusively gave the
corresponding ammonium salts.
The reaction of tin(II) chloride, SnCl2, with the
dimethylaminomethyl phenyl phosphinic acid ester 3a in toluene
at room temperature gave, under the experimental non-inert
conditions employed, the dimethylammoniummethyl phenyl
phosphinic acid ethyl ester trichloridostannate [3a·H][SnCl3]
(Scheme 2).
Figure 1. Displacement ellipsoid (30% probability level) plot and numbering
scheme of the molecular structure in the solid state of compound 2b. Hydrogen
atoms are omitted. Selected interatomic distances (Å) and angles (°): P(11)–
O(11) 1.476(2), P(11)–O(12) 1.592(2), P(11)–C(11) 1.811(3), P(11)–C(20)
1.804(3), O(11)–P(11)–O(12) 113.79(12), O(11)–P(11)–C(11) 113.26(13),
O(11)–P(11)–C(20) 113.56(14), O(12)–P(11)–C(11) 107.14(13), O(12)–P(11)–
C(20) 97.57(12), C(11)–P(11)–C(20) 110.33(13).
The phosphorus atom is tetra-coordinated by O11, O12, C11 and
C20 at distances of 1.476(2) (P11–O11), 1.592(2) (P11–O12),
1.811(3) (P11–C11) and 1.804(3) Å (P11–C20). It exhibits a
distorted tetrahedral environment with angles ranging between
97.57(12) (O12–P11–C20) and 113.79(12)° (O11–P11–O12).
Amination under basic conditions of the aryl(iodomethyl)
phosphinic acid esters 2a and 2b with dimethyl amine gave the
aryl(dimetylaminomethyl) phosphinic acid esters 3a and 3b,
respectively, in fair yields as brownish hygroscopic oils. Both 3a
and 3b show good solubility in common organic solvents such as
dichloromethane, ether, THF, ethyl acetate and acetone.
Solutions of the esters 3a and 3b in CDCl3 show in their 31P{1H}
NMR spectra resonances at δ 39.5 and δ 42.9, respectively.
These are low field shifted as compared to the signals observed
for the phosphinic acid esters 2a and 2b, respectively. From their
solutions in diethyl ether that contained hydrochloric acid (1 M)
colourless crystals of [3a·H]Cl and [3b·H]Cl, respectively, suitable
for single crystal X-ray diffraction analysis were obtained. Both
compounds crystallize in the monoclinic space group P21/c with
four molecules per unit cell. Figure 2 shows the molecular
structure of [3a·H]Cl, and the figure caption contains selected
interatomic distances and angles. Figure S60 (Supporting
Information) shows the molecular structure of [3b·H]Cl. The
amine moieties are protonated and the chloride anions are
involved in NH···Cl hydrogen bonds with similar distances
([3a·H]Cl: N(11)–H(11)···Cl(1) 2.13(2) Å; [3b·H]Cl: N(11)–
H(11)···Cl(1), 2.18(3) Å).
O
+ 4 SnCl2
P
OEt
4
Ph
NMe2
3a
benzene, 25 °C
toluene, 110 °C, 10d
(O2, H2O)
(O2, H2O)
"Sn(OH)2"
4 EtOH
"SnCl(OH)"
Ph
O
Me2
N
P
OEt
P
SnCl3
O
H
4
Ph
Me2N
NHMe2
P
H
Ph
O
O
Cl
Sn
Cl
[3a·H]SnCl3
O
SnCl
[ ]
3 2
O
P
O
H
O
Ph
NMe2
O
H
P
N
Me2
Ph
4
Scheme 2. Reaction of compound 3a with SnCl2 under non-inert conditions
giving either compound [3a·H][SnCl3] or compound 4.
From its benzene solution, the latter crystallized as its benzene
ꢀ
solvate [3a·H][SnCl3]·0.5C6H6 in the triclinic space group P1 with
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10.1002/ejic.201800343
European Journal of Inorganic Chemistry
FULL PAPER
two molecules per unit cell. Figure 3 shows the molecular
structure and the caption contains selected interatomic distances
and angles.
Figure 4. Displacement ellipsoid (30% probability level) plot and numbering
scheme of the structure in the solid state of compound 4·6CH2Cl2. The CH
–
hydrogen atoms, the phenyl carbon atoms (except Ci) and the SnCl3 counter
anions are omitted. Selected interatomic distances [Å]: Sn(1)–O(12) 2.051(3),
Sn(1)–O(32) 2.066(3), Sn(1)–O(52) 2.059(3), Sn(1)–O(72) 2.045(3), Sn(1)–
Cl(1) 2.3645(13), Sn(1)–Cl(2) 2.4051(13), Cl(21) to C(62) 3.466(6), Cl(31) to
C(80) 3.513(5). Interatomic angles [deg]: O(12)–Sn(1)–O(32) 88.36(13), O(12)–
Sn(1)–O(52) 91.51(13), O(12)–Sn(1)–O(72) 179.06(15), O(32)–Sn(1)–O(52)
177.18(14), O(32)–Sn(1)–O(72) 91.03(13), O(52)–Sn(1)–O(72) 89.14(13),
Cl(1)–Sn(1)–O(12) 89.60(11), Cl(1)–Sn(1)–O(32) 91.90(11), Cl(1)–Sn(1)–O(52)
90.91(10), Cl(1)–Sn(1)–O(72) 89.71(10), Cl(2)–Sn(1)–O(12) 90.18(11), Cl(2)–
Sn(1)–O(32) 89.27(10), Cl(2)–Sn(1)–O(52) 87.91(10), Cl(2)–Sn(1)–O(72)
90.52(10), Cl(1)–Sn(1)–Cl(2) 178.80(5). Hydrogen bond distances [Å]:
N(11)···O(51) 2.700(5), N(11)–H(11)···O(51) 1.87(3), N(31)···O(11) 2.639(5),
N(31)–H(31)···O(11) 1.89(4), N(51)···O(71) 2.694(6), N(51)–H(51)···O(71)
1.89(3), N(71)···O(31) 2.683(6), N(71)–H(71)···O(31) 1.85(3).
shows the molecular structure and the figure caption contains
selected interatomic distances and angles.
Compound
4 is a salt composed of a complex dication
[Sn{OP(O)PhCH2NMe2H}4Cl2]2+ and two trichlorido stannate
anions, [SnCl3]–. There are no bonding interactions between the
cation and the anions, the shortest anion-cation distances being
3.466(6) (Cl21···C62) and 3.513(5) Å (Cl31···C80). The Sn(1)
atom of the cation is six-coordinated by Cl(1), Cl(2), O(12), O(32),
O(52), and O(72) at distances of 2.3645(13), 2.4051(13), 2.051(3),
2.066(3), 2.059(3) and 2.045(3) Å, respectively, and exhibits a
slightly distorted octahedral environment with O(12), O(32), O(52)
and O(72) occupying the equatorial positions and Cl(1) and Cl(2)
occupying the axial ones. The slight distortion from the ideal
octahedral geometry is expressed by the Cl(1)–Sn(1)–Cl(2),
O(12)–Sn(1)–O(72), and O(32)–Sn(1)–O(52) angles of 178.80(5),
179.06(15), and 177.18(14)°, respectively, which deviate slightly
from 180°. The P=O oxygen atoms are involved in intramolecular
N–H···O=P hydrogen bonds (N11–H11···O51, 1.87(3) Å; N31–
H31···O11, 1.89(4) Å; N51–H51···O71, 1.89(3) Å; N71–
H71···O31, 1.85(3) Å). As a result of these hydrogen bonds, four
Sn–O–P–O···H–N–C–P–O nine-membered rings are formed.
The [Sn{OP(O)(Ph)CH2NMe2H}4Cl2]2+ dication, in the crystal
actually measured, is of propeller type with the P=O moieties
showing a clockwise orientation. Due to the centrosymmetric
space group the anti-clockwise propeller type molecule is present
in the unit cell as well.
Figure 3. Displacement ellipsoid (30% probability level) plot and numbering
scheme of the structure in the solid state of the dimer of compound
[3a·H][SnCl3]·0.5C6H6. CH hydrogen atoms and solvate molecules are omitted.
Hydrogen bond distances [Å]: N(1)···O(1A) 2.685(3), N(1)–H(1)···O(1A)
1.840(18). Symmetry code: (A) 1-x, 1-y, -z.
The salt [3a·H][SnCl3] consists of a trichlorido stannate anion
(shortest distance to the cation: Sn1·····C4 4.126(4) Å) and the
ammonium cation of compound 3a. The latter forms
a
centrosymmetric head-to-tail dimer via an intermolecular N(1A)–
H(1A)···O(1)–P(1) hydrogen bond with an (O(1)···N(1A) distance
of 2.685(3) Å. As a result of this hydrogen bond, a ten-membered
ring is formed.
Since no de-alkylation took place at room temperature, a solution
of compound 3a in toluene was reacted with SnCl2 under non-
inert conditions at 110 °C for a time period of ten days
reproducibly giving the mixed-valent tin(IV)/tin(II) compound 4 as
colourless crystalline material (Scheme 2). In this context, it is well
known that tin(II) chloride might undergo redox-type reactions
under certain non-inert conditions.[13] Mixed-valent tin(IV)/tin(II)
compounds have been reported in the literature.14] From
dichloromethane solution compound
4 crystallized, as its
dichloromethane solvate 4·6CH2Cl2, as colourless needles in the
A
119Sn{1H} NMR spectrum of a solution of single crystals of
ꢀ
triclinic space group P1 with two molecules per unit cell. Figure 4
compound 4·6CH2Cl2 in CD3CN showed a quintet resonance at δ
–713 ppm (2J(119Sn–31P) = 132 Hz), which is assigned to the
tin(IV) central atom, and a broad singlet resonance at δ –25 ppm
–
(ν1/2 = 216 Hz), which is assigned to the tin(II) atoms of the SnCl3
anions. A 31P{1H} NMR spectrum showed a singlet resonance at
δ 23.0 ppm surrounded by 117/119Sn satellites (2J(31P–117/119Sn) =
126/132 Hz). A 1H NMR spectrum of the same solution displayed
seven signals. The doublets centred at δ 2.68 ppm (4J(1H–1H) =
3.9 Hz) and 3.16 ppm (4J(1H–1H) = 4.3 Hz), respectively, are
assigned to the non-equivalent NCH3 protons. The complex
pattern at δ 3.37 belong to the PCH2 protons. The aromatic
protons appear as complex patterns at δ 7.44 ppm and 7.62 ppm.
A broad singlet (ν1/2 = 27.0 Hz) is related to the NH protons. A 13
C
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10.1002/ejic.201800343
European Journal of Inorganic Chemistry
FULL PAPER
NMR spectrum revealed seven resonances. The doublets centred
at δ 46.6 (3J(13C–31P) = 3.2 Hz) and 47.1 (3J(13C–31P) = 7.0 Hz)
are assigned to the NCH3 carbon atoms. The doublet centred at
δ 57.5 ppm (3J(13C–31P) = 99.4 Hz) is assigned to the PCH2
carbon atom. The four doublets at 129.6 (3J(13C–31P) = 13.5 Hz),
132.7 (3J(13C–31P) = 142.3 Hz), 132.8 (3J(13C–31P) = 10.8 Hz) and
133.9 (3J(13C–31P) = 2.7 Hz), respectively, are assigned to the
meta, ipso, ortho and para carbon atoms, respectively. The NMR
spectra were recorded from crystals that had been washed and
subsequently dried in vacuo in order to remove the
dichloromethane solvate molecules.
In line with the general reactivity of trimethyl halosilanes
towards esters, no reaction was observed between the
phosphinic acid ester 3b and trimethyl chlorosilane, SiMe3Cl,
even after stirring at room temperature for seven days. However,
as monitored by 31P NMR spectroscopy, a complete ester
cleavage was observed by the reaction of 3b with trimethyl
bromosilane, SiMe3Br, after a reaction time of three days at room
temperature (Scheme 3 and Supporting Information).
Figure 5. Displacement ellipsoid (30% probability level) plot and numbering
scheme of the structure in the solid state of compound 5·0.5C7H8. Hydrogen
atoms and the disordered solvent are omitted. Selected interatomic distances
[Å] and angles [deg]: P(1)–C(1) 1.801(6), P(1)–C(10) 1.806(6), P(1)–O(1)
1.527(4), P(1)–O(2) 1.533(4), I(1)–O(2i) 3.940(4), O(1)–P(1)–O(2) 110.6(2),
O(1)–P(1)–C(10) 107.3(3), O(1)–P(1)–C(1) 109.6(2), C(1)–P(1)–O(2) 109.8(3),
C(1)–P(1)–C(10) 114.1(3), O(2)–P(1)–C(10) 105.4(2). Symmetry code: (i) x,
y+1, z.
the latter represents the first crystallographically determined
structure of such a cation.[8]
The phosphinium cation and the iodide anion are separated by
3.940(4)
Å (I1–O2i). The phosphorus atom in compound
5·0.5C7H8 is tetracoordinated by O1, O2, C1, and C10 at
distances of 1.801(6) (P1–C1), 1.806(6) (P1–C10), 1.527(4) (P1–
O1) and 1.533(4) Å (P1–O2). It exhibits a distorted tetrahedral
environment with angles ranging between 114.1(3) (C1–P1–C10)
and 105.4(2)° (O2–P1–C10). The P–O–Si angles of 148.1(3)
(P1–O1–Si1) and 139.6(3)° (P1–O2–Si2) are in the range of
angles published for other compounds containing P–O–Si
moieties (131.7[15] to 157.1°[16]).
A
31P{1H} NMR spectrum of a solution of single crystals of
compound 5·0.5C7H8 in CD3CN showed two resonances at δ 24.5
(ν1/2 = 1.5 Hz, 5) and 32.3 ppm (ν1/2 = 11.2 Hz, 5a), respectively,
with an integral ratio of 1.00 : 1.21. Lowering the temperature to
238 K caused a slight shift of the signals to δ 25.8 and 33.5 ppm,
respectively, broadening (ν1/2 = 94 Hz) of the latter, and a slight
change of the integral ratio to 1.00:1.14. Upon dilution and at room
temperature, the signals appeared at δ 23.9 and 29.3 ppm,
respectively, with an integral ratio of 1.00 : 1.47. A 29Si{1H} NMR
spectrum at room temperature of the original solution displayed
resonances at δ 7.6, 26.2, and 26.4 ppm. The results are
interpreted in terms of an equilibrium involving the diorgano
bis(trimethylsiloxy)phophinium iodide 5, the diorgano phosphinic
trimethylsilyl ester 5a, and trimethyl iodosilane, SiMe3I (Scheme
4).
Scheme 3. The reaction of compound 3b with SiMe3X (X = Br, I) giving
Me2NCH2(Mes)P(O)OSiMe3 (as monitored by NMR spectroscopy, but not
isolated) and compound 5, respectively. Also shown is the reaction of 3b with
SnF2 giving a few crystals of compound 7 and the amorphous material 7a.
The reaction of carefully dried 3b with trimethyl iodosilane,
SiMe3I, in toluene at room temperature gave, within a reaction
time of 15 minutes, single crystals of the diorgano
bis(trimethylsiloxy)phosphinium iodide 5, as its toluene solvate
5·0.5C7H8, which were suitable for X-ray diffraction analysis
(Scheme 3). Compound 5·0.5C7H8 crystallized in the triclinic
ꢀ
space group P1 with two molecules per unit cell. Figure 5 shows
the molecular structure and the figure caption contains selected
interatomic distances and angles. To the best of our knowledge,
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10.1002/ejic.201800343
European Journal of Inorganic Chemistry
FULL PAPER
The phosphorus atoms in all three solvates of compound 6 exhibit
distorted
tetrahedral
environments
with
mesityl,
dimethylaminomethyl and two oxygen substituents at distances
ranging from 1.811(4) (P1–C1, 6·HI·CH2Cl2) to 1.835(4) Å (P1–
C1, 2·6·HI·CH3OH), 1.826(4) (P1–C10, 2·6·HI·CH3OH) to
Scheme 4. Equilibrium involving the diorgano bis(trimethylsiloxy)phophinium
iodide 5, the dimethylaminomethyl mesityl phosphinic trimethylsilyl ester 5a, and
trimethyl iodosilane.
1.840(4)
6·HI·CH2Cl2) to 1.496(3)
Å
(P21–C30, 2·6·HI·CH3OH), 1.484(3) (P1–O1,
(P21–O21, 2·6·HI·CH3OH) and
Å
1.525(3) (P1–O2, 2·6·HI·CH3OH) to 1.563(3)
6·HI·CH2Cl2).
Å (P1–O2,
This interpretation gets further support from a 31P{1H} spectrum of
the original sample to which had been added some SiMe3I. It
exclusively showed a single resonance at δ 24.6 ppm (5)
indicating the equilibrium shown in Scheme 3 being shifted to the
left.
The compounds 2·6·HI·CH3OH, 6·0.5HI and 6·HI·CH2Cl2 all show
similar supramolecular structures. They form head-to-tail dimers
via N–H···O=P hydrogen bridges giving (H–N–C–P=O···)2 ten-
membered rings (Figure 7).
The addition of methanol containing some water to a
solution of compound 5 in acetonitrile followed by evaporating the
volatiles gave the aryl(dimethylammoniummethyl) phosphinic
acid iodide, [Me2HNCH2(Mes)P(O)OH]I, 6, as a white amorphous
solid material (Scheme 3). The latter was crystallized from
methanol, water, and dichloromethane, respectively, to give
single crystals of its solvates 2·6·HI·CH3OH, 6·0.5HI and
6·HI·CH2Cl2, respectively, which are suitable for X-ray diffraction
analysis. Compound 2·6·HI·CH3OH crystallizes as colourless
plates in the monoclinic space group P21/n with four formula units
per asymmetric unit (Supporting Information, Figure S63).
Compound 6·0.5HI crystallizes as colourless plates in the
monoclinic space group C2/c with eight formula units per
asymmetric unit (Supporting Information, Figure S64). Compound
6·HI·CH2Cl2 crystallizes as colourless block in the monoclinic
space group P21/c with four formula units per asymmetric unit.
Figure 6 shows the molecular structure and the figure caption
contains selected interatomic distances and angles.
Figure 7. Structure in the solid state of the head-to-tail dimer of the cation found
in 6·0.5 HI· 0.5 CH3OH, 6·0.5HI as well as in 6·HI·CH2Cl2. Symmetry code: (A)
1-x, 1-y, 1-z.
The NH···OP hydrogen bond distances range between 1.84(2)
(N1–H1···O21, 2·6·HI·CH3OH) and 1.892(17) Å (N1–H1···O1,
6·0.5HI). Despite the N–H···O hydrogen bond there is another
hydrogen bond in each molecular structure. In 2·6·HI·CH3OH and
6·0.5HI, respectively, there is an O–H···O hydrogen bond
(1.583(19) Å, O2–H2···O22, 2·6·HI·CH3OH; 1.65(2) Å, O2–
H2···O2, 6·0.5HI) and in 6·HI·CH2Cl2 there is an O–H···I
interaction (2.51(2) Å, O2–H2···I1).
Single crystalline material of 6·HI·CH2Cl2 was used for the
elemental analysis, IR and NMR spectroscopic and ESI mass
spectrometric studies. A 31P{1H} NMR spectrum of a solution of
6·HI·CH2Cl2 in D2O showed one singlet at δ 32.2 ppm. A 1H NMR
spectrum revealed the absence of Si(CH3)3 protons thus
confirming complete hydrolysis.
The reaction in acetonitrile of in situ generated compound
5·0.5C7H8 with tin(II) fluoride, SnF2, gave a crude reaction mixture
from which after storing at –7 °C an amorphous white powder, 7a,
and a few single crystals as colourless blocks precipitated
(Scheme 3). The single crystals were separated manually and
Figure 6. Displacement ellipsoid (30% probability level) plot and numbering
scheme of the structure in the solid state of compound 6·HI·CH2Cl2. CH
hydrogen atoms are omitted. Selected interatomic distances [Å] and angles
[deg]: P(1)–O(1) 1.484(3), P(1)–O(2) 1.563(3), P(1)–C(1) 1.811(4), P(1)–C(10)
1.834(4), O(1)–P(1)–O(2) 114.72(17), O(1)–P(1)–C(1) 113.98(17), O(2)–P(1)–
C(1) 109.26(17), O(1)–P(1)–C(10) 109.76(17), O(2)–P(1)–C(10) 99.52(18),
C(1)–P(1)–C(10) 108.51(17). Hydrogen bond distances [Å]: O(2)···I(1) 3.319(3),
O(2)–H(2)···I(1) 2.51(2), N(1)···O(1i) 2.702(4), N(1)–H(1)···O(1i) 1.83(2).
Symmetry code: (i) 1-x, 1-y, 1-z.
identified
by
X-ray
diffraction
analysis
as
[{SnII Me2NCH2(Mes)P(O)2}4SnIVF2]I2, 7, containing both Sn(IV)
2
and Sn(II) atoms. It crystallizes in the monoclinic space group
P21/c with four formula units per asymmetric unit. Figure 8 shows
the molecular structure and the figure caption contains selected
interatomic distances and angles.
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10.1002/ejic.201800343
European Journal of Inorganic Chemistry
FULL PAPER
Figure 9. Simplified visualization of the coordination environment about the
Sn(1) atom in compound 7. The distances are given in Å; symmetry code: (i) 1-
x, 1-y, 1-z).
The Supporting Information (Figure S63) shows a simplified
illustration of the coordination environment about the Sn(3) atom.
The Sn(1)–I(1) and Sn(3)–I(2) distances are both considerably
longer than the Sn–I distances in the heteroleptic
organostannylenes RSnI (2.766(2) Å, R = C6H3-2,6-Trip2;[17a]
28544(3) Å, R = C6H2-2,6-{P(O)(Oi-Pr)2}2-4-t-Bu[17b]). However,
they are only slightly longer than the Sn–I distances reported for
Figure 8. Displacement ellipsoid (30% probability level) plot and numbering
scheme of the structure in the solid state of compound 7. Hydrogen atoms and
mesityl groups (except Ci) are omitted. Selected interatomic distances [Å]:
Sn(1)–O(12) 2.2212(16), Sn(1)–O(32) 2.2214(16), Sn(1)–N(14) 2.524(2),
Sn(1)–N(34) 2.607(2), Sn(1)–I(1) 3.4051(2), Sn(1)–I(1i) 3.6504(3), Sn(2)–F(1)
1.9372(14), Sn(2)–F(2) 1.9284(14), Sn(2)–O(11) 2.0284(16), Sn(2)–O(31)
2.0433(16), Sn(2)–O(51) 2.0375(17), Sn(2)–O(71) 2.0313(16), Sn(3)–O(52)
2.1558(16), Sn(3)–O(72) 2.2211(17), Sn(3)–N(54) 2.563(2), Sn(3)–N(74)
2.464(2), Sn(3)–I(2) 3.3011(3), Sn(3)···I(2ii) 5.6528(3). Selected interatomic
angles [deg]: I(1)–Sn(1)–O(12) 170.59(4), N(14)–Sn(1)–N(34) 147.21(6),
O(32)–Sn(1)–I(1i) 154.47(4), F(1)–Sn(2)–O(31) 174.26(7), F(2)–Sn(2)–O(51)
171.37(7), O(11)–Sn(2)–O(71) 178.17(7), I(2)–Sn(3)–O(72) 163.99(5), N(54)–
Sn(3)–N(74) 147.39(7), O(52)–Sn(3)–I(2ii) 163.68(4). Symmetry code: (i) 1-x,
1-y, 1-z; (ii) -x, 0.5+y, 0.5-z.
tin diiodide, SnI2 (range 3.004(5)
–
3.251(5) Å[17c]). The
Sn(3)···I(2ii) distance of 5.6536(5) Å is considerably longer than
the sum of the van der Waals radii of these tow atoms (4.46 Å[17d]).
A close inspection of the interatomic distances suggests that,
formally, compound 7 can be interpreted as being a salt of the
type (A), [SnII L4SnIVF2]I2 [L = MesP(O)(CH2NMe2)O], composed
2
of a complex dication and two iodide anions. The cation contains
both an Sn(IV) and an Sn(II) atom. The complex cation can be
seen as consisting of a central tetrakis(diorganophosphinato)
difluoridostannate anion (Sn1) that complexes in each case via
two P=O→Sn and two N→Sn interactions two Sn2+ dications (Sn1,
Sn3). Given the Sn(1)–I(1) and Sn(3)–I(2) distances as
mentioned above, the salt is a contact ion pair.
An alternative interpretation according to which compound 7 is a
salt of the type (B), [SnIII]2[L4SnIVF2] [L = MesP(O)(CH2NMe2)O],
in which the [L4SnIVF2]2− dianion complexes two [SnIII]+ cations
appears less favoured.
The central Sn(2) atom exhibits
a distorted octahedral
environment. It is cis-coordinated by F(1) and F(2) atoms at
Sn(2)–F(1) and Sn(2)–F(2) distances of 1.9372(14) and
1.9284(14) Å, respectively, and the oxygen atoms O(11), O(31),
O(51), and O(71) of four aryl(dimethylamino)phosphinite ligands
at distances varying between 2.0294(16) (Sn2–O11) and
2.0433(16) Å (Sn2–O31). The distortion from ideal octahedral
geometry is expressed by the F(1)–Sn(2)–O(31), F(2)–Sn(2)–
O(51), and O(11)–Sn(2)–O(71) trans angles of 174.26(7),
171.37(7), and 178.17(7)°, respectively. The Sn(1) atom is in the
oxidation state +II. Considering the lone electron pair, it is [5+2]-
coordinate by O(12), O(32), N(14), N(34), I(1) and I(1i) at Sn(1)–
O(12), Sn(1)–O(32), Sn(1)–N(14), Sn(1)–N(34), Sn(1)–I(1), and
Sn(1)–I(1i) distances of 2.2212(16), 2.2214(16), 2.524(2),
2.607(2), 3.4051(2), and 3.6504(3) Å, respectively. Figure 9
shows the coordination environment about Sn(1) including the
unsymmetrical intermolecular Sn(1)–I(1)–Sn(1i) bridges.
In the CSD data base[8] there are two molecular structures of
Sn(IV) compounds with an SnO2N2I2 substituent pattern.[18, 19]
There was not sufficient quantity of the isolated single crystals of
compound 7 to allow for recording NMR spectra. However,
19F{1H} and 119Sn{1H} NMR spectra recorded from a solution in
CD3CN of the amorphous material 7a obtained from the reaction
between compound 5 and SnF2, and that apparently still
contained little quantity of a compound rather likely to be 7 (or its
isomer with the fluorine substituents at Sn(2) being trans), were
of good quality. The NMR spectroscopic data support with caution
(but not unambiguously) the interpretation that compound 7 is
The Sn(3) atom is in the oxidation state +II as well. Considering
the lone electron pair, it is [5+1]-coordinate by O(52), O(72), N(54),
N(74), and I(2) at Sn(3)–O(52), Sn(3)–O(72), Sn(3)–N(54),
Sn(3)–N(74), and Sn(3)–I(2) distances of 2.1558(16), 2.2211(17),
2.563(2), 2.464(2), and 3.3011(3) Å, respectively.
present. The Supporting Information contains
a detailed
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10.1002/ejic.201800343
European Journal of Inorganic Chemistry
FULL PAPER
discussion of the 19F (Figure S56) and 119Sn (Figure S57) NMR
spectra.
positions. Their occupancies were allowed to refine freely until a constant
number (0.76100/0.23900) was obtained. The severely disordered
electron densities of non-coordinating solvent molecules of compound
4·6CH2Cl2 and the residual electron density of 7 (for which no meaningful
solvent molecule could be assigned) were modelled by the SQUEEZE
routine of the program Platon[22] to improve the main part of the structures.
The iodide anion I(1) and the proton H(2) in compound 6·0.5HI have an
occupancy value of 0.5. Due to packing effects there are solvent-
accessible voids (about 240 Å3) in compound 7. The NH protons of
compounds [3a·H]SnCl3·0.5C6H6, 4·6CH2Cl2, 2·6·HI·CH3OH, 6·0.5HI and
6·HI·CH2Cl2, respectively, and OH protons of compounds 2·6·HI·CH3OH
and 6·HI·CH2Cl2, respectively, are located in the difference Fourier map
and refined freely, NH and OH distances are restrained to a fix value.
Conclusions
Aryl(dimethylaminomethyl)phosphinic acid esters are accessible
in moderate yields. Ester cleavage was achieved by reaction with
trimethyl
iodosilane
to
give
a
diorgano
bis(trimethylsiloxy)phophinium iodide. In solution, the latter is
involved in an equilibrium with the corresponding
dimethylaminomethyl mesityl phosphinic trimethylsilyl ester and
trimethyl iodosilane. This equilibrium is the result of a competition
between the formation of an P=O double (in the classical sense)
and an Si-O bond. Under non-inert conditions, the title
compounds react with tin(II) halides in redox-type reactions to
give mixed-valent dinuclear tin salts with interesting
supramolecular structures. Although the latter results show some
“character of serendipity”, they illustrate the general high potential
α-aminoalkyl(organo)phosphinic acid esters have as ligands in
coordination chemistry for both main group and transition metals.
This holds even more so as tailoring their properties by variation
of the substituents at both the nitrogen and phosphorus atoms
can easily be achieved.
CCDC-1818331 (2b), CCDC-1818332 ([3a·H]Cl), CCDC-1818333
([3b·H]Cl), CCDC-1818334 ([3a·H]SnCl3·0.5C6H6) CCDC-1818335
(4·6CH2Cl2),
CCDC-1818336
(5·0.5C7H8),
CCDC-1818337
(2·6·HI·CH3OH), CCDC-1818338 (6·0.5HI), CCDC-1818339 (6·HI·CH2Cl2)
and CCDC-1818340 (7) contain the supplementary crystallographic data
for this paper. This data can be obtained free of charge from The
Cambridge
Crystallographic
Data
Centre
via
www.ccdc.cam.ac.uk/data_request/cif. For decimal rounding of numerical
parameters and su values the rules of IUCr have been employed.[23] All
figures were generated using ORTEP III[24] or Diamond[25] visualization
software.
Diethyl phenyl phosphonite, PhP(OEt)2 (1a)
Triethyl phosphite (54.0 mL, 318 mmol) was added in one portion at 0 °C
to a solution of phenyl magnesium bromide [prepared from phenyl bromide
(20.00 g, 127 mmol) and magnesium turnings (3.72 g, 152 mmol)] in thf
(300 mL) and heated 2 h at 65 °C. After evaporation of the solvent and
addition of iso-hexane (300 mL), the resulting suspension was filtered
through a glass frit (G3) and the residue was washed several times with
iso-hexane (3x75 mL). The solvent of the filtrate was removed in vacuo.
The resulting residue was distilled (100 °C/ 8 mbar) giving diethyl phenyl
phosphonite (1a) as a colourless liquid (18.62 g, 94.0 mmol, 74%).
Experimental Section
General. Unless otherwise stated, all reactions were carried out under an
atmosphere of argon grade 4.6 in flame-dried glassware using Schlenk
technique. Solvents including NMR solvents were purified by distillation
from appropriate drying agents under argon and stored over molecular
sieves. NMR spectra were recorded at room temperature on a Varian
Mercury 200, a Bruker AV DPX 300 and a Bruker AV 400 Avance III HD
NanoBay instrument. NMR chemical shifts are given in ppm and were
referenced to Me4Si (1H, 13C, 29Si) [using residual solvent signal: CDCl3 1H
7.27 ppm, 13C 77.0 ppm; CD3CN 1H 1.94 ppm, 13C 1.32 ppm; D2O 1H 4.79
ppm] H3PO4 (85%, 31P), Me4Sn (119Sn). 29Si{1H} NMR spectra were
obtained using an INEPT experiment. Elemental analyses were performed
on a LECO-CHNS-932 analyser. The samples were weight at air.
Uncorrected melting points were measured on a Büchi M-560. The
electrospray mass spectra were recorded with a Thermoquest-Finnigan
instrument using aqueous acetonitrile or methanol as the mobile phase.
The concentration was 0.1 mg/mL with a flow rate of 10 µL/min. The
experimental isotopic pattern matched the theoretical ones. IR spectra
(cm-1) were measured on a Perkin Elmer Spectrum Two (ATR). Column
chromatography was performed on silica gel (0.035-0.070 mm, 60 Å,
Acros). TLC plates (silica gel, F254, Merck) were used.
1H NMR (200.13 MHz, CDCl3): δ 1.29 (dt, 3J(1H–1H) = 7.0 Hz, 4J(1H–31P)
= 0.5 Hz, 6H, OCH2CH3), 3.90 (complex pattern, 4H, OCH2CH3), 7.40
(complex pattern, 3H, CmH, CpH), 7.60 (complex pattern, 2H, CoH).
13C{1H} NMR (100.63 MHz, CDCl3): δ 17.1 (d, 3J(13C–31P) = 5.0 Hz,
2
4
OCH2CH3), 62.4 (d, J(13C–31P) = 10.4 Hz, OCH2CH3), 128.1 (d, J(13C–
31P) = 5.0 Hz, CmCH3), 129.6 (d, 1J(13C–31P) = 20.3 Hz, CoCH3), 129.6 (s,
CpCH3), 141.7 (2J(13C–31P) = 19.1 Hz, CiCH3). 31P{1H} NMR (81.02 MHz,
CDCl3): δ 157.0.
Diethyl mesityl phosphonite, MesP(OEt)2 (1b)
Triethyl phosphite (43.0 mL, 250 mmol) was added at 0 °C at once to a
solution of mesityl magnesium bromide [prepared from mesityl bromide
(19.90 mL, 100 mmol) and magnesium turnings (2.67 g, 110 mmol)] in THF
(250 mL) and heated 2 h at 65 °C. After evaporation of the solvent and
addition of iso-hexane (250 mL), the resulting suspension was filtered
through a glass frit (G3) and the residue was washed several times with
iso-hexane (3x75 mL). The solvent of the filtrate was removed in vacuo.
The resulting residue was distilled (110 °C/ 8 mbar) giving diethyl mesityl
phosphonite (1b) as a colourless liquid (15.79 g, 79.3 mmol, 79%).
Crystallography. Intensity data for all crystals were collected on an
XcaliburS CCD diffractometer (Oxford Diffraction) using Mo-Kα radiation
at 173 K. The structures were solved with direct methods using SHELXS-
97[20] (compounds 2b, [3a·H]Cl, [3a·H]SnCl3·0.5C6H6, [3b·H]Cl, and
4·6CH2Cl2) and SHELXS-2014/7[20,21] (compound 2·6·HI·CH3OH, 6·0.5HI
and 6·HI·CH2Cl2) or SHELXT[21] (compound 5 and 7) and refinements were
carried out against F2 by using SHELXL-2014/7.[20,21] The C–H hydrogen
atoms were positioned with idealized geometry and refined using a riding
model. All non-hydrogen atoms were refined using anisotropic
displacement parameters. In compound [3a·H]Cl the carbon atoms C23
and C24 are affected by disorder and refined by a split model over two
1H NMR (300.13 MHz, CDCl3): δ 1.36 (t, 3J(1H–1H) = 7.0 Hz, 6H,
OCH2CH3), 2.32 (s, 3H, CpCH3), 2.68 (s, 6H, CoCH3), 4.01 (dq, 3J(1H–1H)
= 7.0 Hz, 3J(1H–31P) = 9.1 Hz, 4H, OCH2CH3), 6.88 (d, 4J(1H–31P) = 2.1 Hz,
2H, CmH). 13C{1H} NMR (75.48 MHz, CDCl3): δ 17.3 (d, 3J(13C–31P) = 6.3
This article is protected by copyright. All rights reserved.

10.1002/ejic.201800343
European Journal of Inorganic Chemistry
FULL PAPER
3
Hz, OCH2CH3), 21.0 (s, CpCH3), 21.6 (d, J(13C–31P) = 19.6 Hz, CoCH3),
3J(1H–1H) = 7.1 Hz, 3H, OCH2CH3), 2.30 (s, 3H, CpCH3), 2.62 (s, 6H,
CoCH3), 3.22 (ABX system, 2J(1H–1H) = 12.6 Hz, 2J(1H–31P) = 4.6 Hz, 1H,
PCH2I), 3.28 (ABX system, 2J(1H–1H) = 12.6 Hz, 2J(1H–31P) = 8.9 Hz, 1H,
PCH2I), 4.03 (complex pattern, 1H, OCH2CH3), 4.25 (complex pattern, 1H,
OCH2CH3), 6.92 (d, 4J(1H–31P) = 4.0 Hz, 2H, CmH). 1H NMR (600.29 MHz,
CDCl3): δ 1.35 (t, 3J(1H–1H) = 7.1 Hz, 3H, OCH2CH3), 2.30 (s, 3H, CpCH3),
2.62 (s, 6H, CoCH3), 3.21 (ABX system, 2J(1H–1H) = 12.6 Hz, 2J(1H–31P) =
4.5 Hz, 1H, PCH2I), 3.28 (ABX system, 2J(1H–1H) = 12.6 Hz, 2J(1H–31P) =
9.1 Hz, 1H, PCH2I), 4.02 (complex pattern, 1H, OCH2CH3), 4.24 (complex
pattern, 1H, OCH2CH3), 6.92 (d, 4J(1H–31P) = 4.0 Hz, 2H, CmH). 13C{1H}
NMR (75.48 MHz, CDCl3): δ –4.6 (d, 3J(13C–31P) = 96.0 Hz, OCH2I), 16.4
(d, 3J(13C–31P) = 6.3 Hz, OCH2CH3), 21.1 (s, CpCH3), 23.4 (d, 4J(1H–31P)
= 2.3 Hz, CoCH3), 61.5 (d, 2J(13C–31P) = 6.1 Hz, OCH2CH3), 122.2 (d,
1J(13C–31P) = 130.9 Hz, Ci), 130.9 (d, 3J(13C–31P) = 13.6 Hz, Cm), 142.4 (d,
4J(13C–31P) = 2.9 Hz, Cp), 143.7 (d, 2J(13C–31P) = 11.5 Hz, Co). 31P{1H}
NMR (121.50 MHz, CDCl3): δ 38.0. Elemental analysis calcd. for
C12H18IO2P: C 40.9, H 5.2; found C 41.0, H 5.3. ESI MS (acetonitrile, m/z,
positive mode): 298 [MesP(O)(OEt)2+CH3CN+H]+, 353 [2b+H]+, 375
[2b+Na]+, 416 [2b+CH3CN+Na]+, 727 [2·2b+Na]+. IR: P=O 1219 (s).
64.1 (d, 2J(13C–31P) = 21.5 Hz, OCH2CH3), 129.6 (d, 4J(13C–31P) = 3.7 Hz,
CmCH3), 134.7 (d, 1J(13C–31P) = 19.0 Hz, CiCH3), 139.8 (s, CpCH3), 141.7
(2J(13C–31P) = 19.2 Hz, CoCH3). 31P{1H} NMR (121.50 MHz, CDCl3): δ
177.5.
Iodomethyl phenyl phosphinic acid ethyl ester, ICH2(Ph)P(O)OEt (2a)
Diethyl phenyl phosphonite (1a, 17.11 g, 86.3 mmol) and diiodomethane
(40.0 mL, 133.0 g, 497.0 mmol) were heated 14 h at 110 °C. During the
reaction the ethyl iodide was distilled continuously. After distillation of the
excess diiodomethane (98 °C, 8 mbar) the crude product was purified by
column chromatography (diethyl ether, Rf 0.24). Compound 2a was
obtained as colourless oil (24.74 g, 79.8 mmol, 92%).
1H NMR (200.13 MHz, CDCl3): δ 1.36 (dt, 3J(1H–1H) = 7.1 Hz, 4J(1H–31P)
= 0.3 Hz, 3H, OCH2CH3), 3.18 (ABX system, 2J(1H–1H) = 12.8 Hz, 2J(1H–
31P) = 7.1 Hz, 1H, PCH2I), 3.20 (ABX system, 2J(1H–1H) = 12.8 Hz, 2J(1H–
31P) = 8.0 Hz, 1H, PCH2I), 4.07 (complex pattern, 1H, OCH2CH3), 4.20
(complex pattern, 1H, OCH2CH3), 7.55 (complex pattern, 3H, CmH, CpH),
7.85 (complex pattern, 2H, CoH). 1H NMR (400.25 MHz, CDCl3): δ 1.36 (dt,
Dimethylaminomethyl phenyl phosphinic acid ethyl ester,
Me2NCH2(Ph)P(O)OEt, (3a)
3J(1H–1H) = 7.0 Hz, 3H, OCH2CH3), 3.18 (ABX system, J(1H–1H) = 12.9
2
Hz, 2J(1H–31P) = 6.9 Hz, 1H, PCH2I), 3.21 (ABX system, 2J(1H–1H) =
12.9 Hz, 2J(1H–31P) = 8.2 Hz, 1H, PCH2I), 4.06 (complex pattern, 1H,
OCH2CH3), 4.21 (complex pattern, 1H, OCH2CH3), 7.50 (complex pattern,
2H, CmH), 7.59 (complex pattern, 1H, CpH), 7.84 (complex pattern, 2H,
Compound 2a (10 g, 32.3 mmol), dimethyl amine (17.0 mL, 5.6 M in
ethanol, 95.2 mmol) and sodium carbonate (10.22 g, 96.4 mmol) were
heated 14 hours in ethanol (30 mL) at 78 °C. The reaction mixture was
cooled to room temperature, diluted with water (20 mL) and extracted with
dichloromethane (5x40 mL). The combined organic phases were treated
with diluted hydrochloric acid (1 M) to pH 1 and extracted with water
(5x40 mL). The combined aqueous phases were treated with sodium
hydroxide solution (1 M) to pH 14 and extracted with dichloromethane
(5x40 mL). The combined organic phases were dried with magnesium
sulphate, filtrated and the solvent was evaporated in vacuo. After filtration
(silica gel, diethyl ether) the amine 3a (4.03 g, 17.7 mmol, 55%) was
obtained as brownish oil. From hydrochloric acid in ether (1 M) colourless
crystals of [3a·H]Cl suitable for single crystal diffraction analysis with a
melting point of 211 °C were obtained.
3
CoH). 1H NMR (600.25 MHz, CDCl3): δ 1.36 (dt, J(1H–1H) = 7.1 Hz, 3H,
OCH2CH3), 3.17 (ABX system, 2J(1H–1H) = 12.8 Hz, 2J(1H–31P) = 6.8 Hz,
1H, PCH2I), 3.21 (ABX system, 2J(1H–1H) = 12.8 Hz, 2J(1H–31P) = 8.2 Hz,
1H, PCH2I), 4.06 (complex pattern, 1H, OCH2CH3), 4.21 (complex pattern,
1H, OCH2CH3), 7.50 (complex pattern, 2H, CmH), 7.59 (complex pattern,
1H, CpH), 7.84 (complex pattern, 2H, CoH). 1H NMR (700.19 MHz, CDCl3):
δ 1.36 (dt, 3J(1H–1H) = 7.1 Hz, 3H, OCH2CH3), 3.17 (ABX system, 2J(1H–
1H) = 12.8 Hz, 2J(1H–31P) = 6.8 Hz, 1H, PCH2I), 3.21 (ABX system, 2J(1H–
1H) = 12.8 Hz, 2J(1H–31P) = 8.2 Hz, 1H, PCH2I), 4.06 (complex pattern, 1H,
OCH2CH3), 4.21 (complex pattern, 1H, OCH2CH3), 7.50 (complex pattern,
2H, CmH), 7.59 (complex pattern, 1H, CpH), 7.84 (complex pattern, 2H,
3
CoH). 13C{1H} NMR (100.63 MHz, CDCl3): δ –7.8 (d, J(13C–31P) = 101.1
Hz, OCH2I), 16.2 (d, 3J(13C–31P) = 6.3 Hz, OCH2CH3), 61.8 (d, 2J(13C–31P)
= 6.2 Hz, OCH2CH3), 127.9 (d, 1J(13C–31P) = 135.6 Hz, Ci), 128.3 (d,
3J(13C–31P) = 13.1 Hz, Cm), 131.8 (d, 2J(13C–31P) = 9.8 Hz, Co), 132.6 (d,
2J(13C–31P) = 2.7 Hz, Cp). 31P{1H} NMR (81.02 MHz, CDCl3): δ 35.4.
Elemental analysis for C9H12IO2P calcd. C 34.9, H 3.9; found C 34.4, H
4.2. ESI MS (acetonitrile, m/z, positive mode): 310 [2a+H]+, 352
[2a+MeCN+H]+, 374 [2a+MeCN+Na]+, 643. [2·2a+H]+. IR: P=O 1224 (s).
1H NMR (300.13 MHz, CDCl3): δ 1.23 (t, 3J(1H–1H) = 7.1 Hz, 3H,
OCH2CH3), 2.27 (s, 6H, PCH2N(CH3)2), 2.82 (complex pattern, 2H,
PCH2N(CH3)2), 3.85 (complex pattern, 1H, OCH2CH3), 4.03 (complex
pattern, 1H, OCH2CH3), 7.45 (complex pattern, 3H, CmH, CpH), 7.76
(complex pattern, 2H, CoH). 1H NMR (400.25 MHz, CDCl3): δ 1.30 (t,
3J(1H–1H) = 7.1 Hz, 3H, OCH2CH3), 2.35 (s, 6H, PCH2N(CH3)2), 2.90
(complex pattern, 2H, PCH2N(CH3)2), 3.90 (complex pattern, 1H,
OCH2CH3), 4.12 (complex pattern, 1H, OCH2CH3), 7.48 (complex pattern,
2H, CmH), 7.55 (complex pattern, 1H, CpH), 7.83 (complex pattern, 2H,
CoH). 1H NMR (600.29 MHz, CDCl3): δ 1.30 (t, 3J(1H–1H) = 7.0 Hz, 3H,
OCH2CH3), 2.35 (s, 6H, PCH2N(CH3)2), 2.89 (complex pattern, 2H,
PCH2N(CH3)2), 3.90 (complex pattern, 1H, OCH2CH3), 4.12 (complex
pattern, 1H, OCH2CH3), 7.48 (complex pattern, 2H, CmH), 7.55 (complex
pattern, 1H, CpH), 7.83 (complex pattern, 2H, CoH). 1H NMR (700.19 MHz,
CDCl3): δ 1.29 (t, 3J(1H–1H) = 7.1 Hz, 3H, OCH2CH3), 2.35 (s, 6H,
PCH2N(CH3)2), 2.87 (ABX system, 2J(1H–1H) = 15.2 Hz, 2J(1H–31P) = 8.1
Hz, 1H, PCH2N(CH3)2), 2.88 (ABX system, 2J(1H–1H) = 15.2 Hz, 2J(1H–
31P) = 9.9 Hz, 1H, PCH2N(CH3)2), 3.90 (complex pattern, 1H, OCH2CH3),
4.11 (complex pattern, 1H, OCH2CH3), 7.48 (complex pattern, 2H, CmH),
7.55 (complex pattern, 1H, CpH), 7.82 (complex pattern, 2H, CoH). 13C{1H}
NMR (75.48 MHz, CDCl3): δ 16.4 (d, 3J(13C–31P) = 6.2 Hz, OCH2CH3), 47.7
(d, 3J(13C–31P) = 9.6 Hz, PCH2N(CH3)2), 58.5 (d, 3J(13C–31P) = 119.8 Hz,
PCH2N(CH3)2), 60.7 (d, 3J(13C–31P) = 6.7 Hz, OCH2CH3), 128.5 (d, 3J(13C–
31P) = 12.3 Hz, Cm), 130.4 (d, 1J(13C–31P) = 128.5 Hz, Ci), 131.8 (d, 2J(13C–
31P) = 9.6 Hz, Co), 132.3 (d, 4J(13C–31P) = 2.7 Hz, Cp). 31P{1H} NMR
(121.50 MHz, CDCl3): δ 39.5 (1J(31P–13C) = 121 Hz). Elemental analysis
Iodomethyl mesityl phosphinic acid ethylester, ICH2(Mes)P(O)OEt,
(2b)
Diethyl mesitylphosphonite (1b) (13.42 g, 55.9 mmol) and diiodomethane
(27.0 mL, 89.8 g, 335 mmol) were heated 14 h at 110 °C. During the
reaction the ethyl iodide was distilled continuously. After distillation of the
excess diiodomethane (98 °C, 8 mbar) the crude product was purified by
crystallization and repetitive recrystallization from iso-hexane. Compound
2b was obtained as colourless to yellow crystals (13.17 g, 37.4 mmol,
67%) with a melting point of 65 °C.
1H NMR (300.13 MHz, CDCl3): δ 1.34 (t, 3J(1H–1H) = 7.1 Hz, 3H,
OCH2CH3), 2.29 (s, 3H, CpCH3), 2.60 (s, 6H, CoCH3), 3.21 (ABX system,
2J(1H–1H) = 12.6 Hz, 2J(1H–31P) = 4.6 Hz, 1H, PCH2I), 3.27 (ABX system,
2J(1H–1H) = 12.6 Hz, 2J(1H–31P) = 9.0 Hz, 1H, PCH2I), 4.03 (complex
pattern, 1H, OCH2CH3), 4.22 (complex pattern, 1H, OCH2CH3), 6.91 (d,
4J(1H–31P) = 4.0 Hz, 2H, CmH). 1H NMR (400.25 MHz, CDCl3): δ 1.35 (t,
This article is protected by copyright. All rights reserved.

10.1002/ejic.201800343
European Journal of Inorganic Chemistry
FULL PAPER
for C11H18NO2P calcd. C 58.1, H 8.0, N 6.2; found C 58.4, H 8.0, N 6.2.
ESI MS (acetonitrile, m/z, positive mode): 228 [3a+H]+, 242 (unassigned),
455 [2·3a+H]+, 477 [2·3a+Na]+. IR: P=O 1218 (s).
NMR (121.50 MHz, CDCl3): δ 42.9. Elemental analysis calcd. for
C14H24NO2P·0.25H2O: C 61.4, H 9.0, N 5.1; found C 61.4, H 9.0, N 5.1.
ESI
MS
(acetonitrile,
m/z,
positive
mode):
242
[MesP(O)(OH)CH2NMe2+H]+, 264 [MesP(O)(OH)CH2NMe2+Na]+, 270
[3b+H]+, 292 [3b+Na]+. IR: P=O 1214 (s).
Dimethylammoniummethyl phenyl phosphinic acid ethylester
trichlorido
stannate,
[Me2HNCH2(Ph)P(O)OEt][SnCl3]
([3a·H][SnCl3]·0.5C6H6)
Dichloridotetrakis(dimethylammoniummethyl)phenylphosphinato)ti
n
bis(trichloridostannate), [SnCl2{Me2HNCH2(Ph)P(O)O}4][SnCl3]2,
(4·6CH2Cl2)
A solution of the amine 3a (100 mg, 0.44 mmol) and tin(II) chloride (83 mg,
0.44 mmol) in benzene (5 mL) was stirred at room temperature for 15
hours. Upon slowly evaporating the solution under non-inert conditions, a
solid precipitate formed from which a few colourless plate-shaped single
crystals of [3a·H][SnCl3]·0.5C6H6 suitable for X-ray diffraction analysis
were separated manually. Because of insufficient quantity of the material,
no elemental analysis could be performed and no NMR spectra could be
recorded.
A solution of the amine 3a (0.250 g, 1.10 mmol) and tin(II) chloride (0.208
g, 1.10 mmol) in toluene (5 mL) was heated for a time period of 10 days at
110 °C. After evaporation of the solvent the reaction mixture was dissolved
in dichloromethane (5 mL). Storage at –8 °C under non-inert conditions
gave compound 4, as its dichloromethane solvate 4·6CH2Cl2 (0.324 mg,
0.233 mmol, 85%), as colourless needles with a melting point of 79 °C.
Dimethylaminomethyl
Me2NCH2(Mes)P(O)OEt, (3b)
mesityl
phosphinic
acid
ethylester,
1H NMR (300.13 MHz, CD3CN): δ 2.68 (d, 4J(1H–1H) = 3.9 Hz, 12H,
PCH2NH(CH3)2), 3.16 (d, 4J(1H–1H) = 4.3 Hz, 12H, PCH2NH(CH3)2), 3.37
(complex pattern, 8H, PCH2NH(CH3)2), 7.44 (complex pattern, 8H, CoH),
7.62 (complex pattern, 12H, CmH, CpH), 10.70 (s, ν1/2 = 27.0 Hz, 4H,
PCH2NH(CH3)2). 13C{1H} NMR (75.48 MHz, CD3CN): δ 46.6 (d, 3J(13C–
31P) = 3.2 Hz, PCH2NH(CH3)ax(CH3)eq), 47.1 (d, 3J(13C–31P) = 7.0 Hz,
PCH2NH(CH3)ax(CH3)eq), 57.5 (d, 1J(13C–31P) = 99.4 Hz, PCH2NH(CH3)2),
129.6 (d, 3J(13C–31P) = 13.5 Hz, Cm), 132.7 (d, 1J(13C–31P) = 142.3 Hz, Ci),
132.8 (d, J(13C–31P) = 10.8 Hz, Co), 133.9 (d, J(13C–31P) = 2.7 Hz, Cp).
31P{1H} NMR (121.50 MHz, CD3CN): δ 23.0 (s, 2J(31P–117/119Sn) =
126/132 Hz). 119Sn{1H} NMR (111.84 MHz, CD3CN): δ –713.3 (qu,
2J(119Sn–31P) = 132 Hz, Sn(VI)), –25.3 (s, 1/2 = 216 Hz, Sn(II)). Elemental
analysis calcd. for C36H56Cl8N4O8P4Sn3: C 30.1, H 3.9, N 3.9; found C
29.9, H 4.4, N 3.7. ESI MS (acetonitrile, m/z, positive mode): 200
[(CH3)2NCH2PPh(O)(OH)+H]+, 242 [(CH3)2NCH2PPh(O)(OH)+CH3CN+H]+,
Compound 2b (10 g, 28.4 mmol), dimethyl amine (15.2 mL, 5.6 M in
ethanol, 84.0 mmol) and sodium carbonate (9.03 g, 85.2 mmol) were
heated 14 hours in ethanol (30 mL) at 78 °C. The reaction mixture was
cooled to rt, diluted with water (20 mL) and extracted with dichloromethane
(5x40 mL). The combined organic phases were treated with diluted
hydrochloric acid (1 M) to pH 1 and extracted with water (5x40 mL). The
combined aqueous phases were treated with sodium hydroxide solution (1
M) to pH 14 and extracted with dichloromethane (5x40 mL). The combined
organic phases were dried with magnesium sulphate and filtrated. The
solvent of the filtrate was evaporated in vacuo giving the amine 3b (3.89
g, 14.4 mmol, 51%) as brownish oil. From hydrochloric acid in ether (1 M)
colourless crystals of [3b·H]Cl suitable for single crystal diffraction analysis
with a melting point of 253 °C were obtained.
2
4
587
[SnCl22++(CH3)2NCH2PPh(O)(OH)+(CH3)2NCH2PPh(O)2–]+,
786
[SnCl22++ 2(CH3)2NCH2PPh(O)(OH)+(CH3)2NCH2PPh(O)2]+. IR: P=O 1178
(s).
1H NMR (300.13 MHz, CDCl3): δ 1.31 (t, 3J(1H–1H) = 7.1 Hz, 3H,
OCH2CH3), 2.27 (s, 3H, CpCH3), 2.34 (s, 6H, N(CH3)2), 2.62 (d, 2J(1H–31P)
= 1.0 Hz, 6H, CoCH3), 2.86 (ABX system, 2J(1H–1H) = 14.9 Hz, 2J(1H–31P)
= 9.1 Hz, 1H, PCH2N(CH3)2), 2.88 (ABX system, 2J(1H–1H) = 14.9 Hz,
2J(1H–31P) = 6.6 Hz, 1H, PCH2N(CH3)2), 3.88 (complex pattern, 1H,
Attempt to de-alkylate 3b with trimethyl chlorosilane
Trimethyl chlorosilane (0.24 g, 2.22 mmol) was added to a solution of the
amine 3b (0.20 g, 0.74 mmol) in toluene (5 mL). Subsequently, NMR
samples of the reaction mixture were taken at variable times (0.5 d, 1.5 d,
2.5 d, 3.5 d, 5 d, 8 d, 13 d, 25 d).
4
OCH2CH3), 4.15 (complex pattern, 1H, OCH2CH3), 6.89 (d, J(1H–31P) =
3.6 Hz, 2H, CmH). 1H NMR (400.25 MHz, CDCl3): δ 1.31 (t, 3J(1H–1H) = 7.1
Hz, 3H, OCH2CH3), 2.27 (s, 3H, CpCH3), 2.35 (s, 6H, N(CH3)2), 2.62 (s, 6H,
CoCH3), 2.86 (ABX system, 2J(1H–1H) = 14.8 Hz, 2J(1H–31P) = 9.1 Hz, 1H,
PCH2N(CH3)2), 2.89 (ABX system, 2J(1H–1H) = 14.8 Hz, 2J(1H–31P) = 6.3
Hz, 1H, PCH2N(CH3)2), 3.87 (complex pattern, 1H, OCH2CH3), 4.17
(complex pattern, 1H, OCH2CH3), 6.89 (d, 4J(1H–31P) = 3.6 Hz, 2H, CmH).
1H-NMR (600.29 MHz, CDCl3): δ 1.31 (t, 3J(1H–1H) = 7.1 Hz, 3H,
OCH2CH3), 2.27 (s, 3H, CpCH3), 2.35 (s, 6H, N(CH3)2), 2.62 (d, 6H, CoCH3),
2.87 (ABX system, 2J(1H–1H) = 15.0 Hz, 2J(1H–31P) = 9.5 Hz, 1H,
PCH2N(CH3)2), 2.90 (ABX system, 2J(1H–1H) = 15.0 Hz, 2J(1H–31P) = 6.2
Hz, 1H, PCH2N(CH3)2), 3.87 (complex pattern, 1H, OCH2CH3), 4.17
(complex pattern, 1H, OCH2CH3), 6.89 (d, 4J(1H–31P) = 3.5 Hz, 2H, CmH).
1H NMR (700.19 MHz, CDCl3): δ 1.31 (t, 3J(1H–1H) = 7.1 Hz, 3H,
OCH2CH3), 2.27 (s, 3H, CpCH3), 2.35 (s, 6H, N(CH3)2), 2.62 (d, 6H, CoCH3),
2.86 (ABX system, 2J(1H–1H) = 15.0 Hz, 2J(1H–31P) = 9.5 Hz, 1H,
PCH2N(CH3)2), 2.89 (ABX system, 2J(1H–1H) = 15.0 Hz, 2J(1H–31P) = 6.1
Hz, 1H, PCH2N(CH3)2), 3.87 (complex pattern, 1H, OCH2CH3), 4.17
(complex pattern, 1H, OCH2CH3), 6.89 (d, 4J(1H–31P) = 3.7 Hz, 2H, CmH).
13C{1H} NMR (75.48 MHz, CDCl3): δ 16.2 (d, 3J(13C–31P) = 6.4 Hz,
OCH2CH3), 20.7 (s, CpCH3), 23.0 (d, 4J(1H–31P) = 1.9 Hz, CoCH3), 47.5 (d,
3J(13C–31P) = 9.4 Hz, PCH2N(CH3)2), 59.6 (d, 2J(13C–31P) = 6.5 Hz,
OCH2CH3), 59.9 (d, 1J(13C–31P) = 115.2 Hz, PCH2N(CH3)2), 124.1 (d,
1J(13C–31P) = 116.3 Hz, Ci), 130.5 (d, 3J(13C–31P) = 12.6 Hz, Cm), 141.3 (d,
4J(13C–31P) = 2.1 Hz, Cp), 143.3 (d, 2J(13C–31P) = 11.1 Hz, Co). 31P{1H}
Time-resolved 31P{1H} NMR spectra (162.03 MHz, 0.5 d, 1.5 d, 2.5 d, 3.5
d, 5 d; 242.99 MHz, 8 d, 13 d, 25 d) of the reaction mixture (0.5 mL) with
C6D6 (0.1 mL). 0.5 d: δ 41.9 (s, 98.7%), 13.4 (s, 1.3%); 1.5 d: δ 41.9 (s,
98.4%), 13.4 (s, 1.6%); 2.5 d: δ 41.9 (s, 98.6%), 13.4 (s, 1.4%); 3.5 d: δ
41.9 (s, 98.6%), 13.4 (s, 1.4%); 5 d: δ 41.9 (s, 98.7%), 13.4 (s, 1.3%); 8 d:
δ 41.9 (s, 98.4%), 13.4 (s, 1.6%); 13 d: δ 41.9 (s, 98.2%), 13.4 (s, 1.8%);
15 d: δ 41.9 (s, 98.1%), 13.4 (s, 1.9%).
Attempt to de-alkylate 3b with trimethyl bromosilane
Trimethyl bromosilane (0.34 g, 2.22 mmol) was added to a solution of the
amine 3b (0.20 g, 0.74 mmol) in toluene (5 mL). Subsequently, NMR
samples of the reaction mixture were taken at variable times (0.5 d, 1.5 d,
2.5 d, 3.5 d, 5 d, 8 d).
Time-resolved 31P{1H} NMR spectra (162.03 MHz, 0.5 d, 1.5 d, 2.5 d, 3.5
d, 5 d; 242.99 MHz, 8 d) of the reaction mixture (0.5 mL) in C6D6 (0.1 mL).
0.5 d: δ 41.7 (s, 11.9%), 33.4 (s, 86.6%), 13.4 (s, 1.5%); 1.5 d: δ 41.7 (s,
8.9%), 33.4 (s, 89.9%), 13.4 (s, 1.2%); 2.5 d: δ 41.7 (s, 4.3%), 33.4 (s,
94.6%), 13.4 (s, 1.1%); 3.5 d: δ 41.7 (s, 2.9%), 33.4 (s, 95.8%), 13.4 (s,
This article is protected by copyright. All rights reserved.

10.1002/ejic.201800343
European Journal of Inorganic Chemistry
FULL PAPER
1.3%); 5 d: δ 41.7 (s, 0.6%), 33.4 (s, 98.2%), 13.4 (s, 1.2%); 8 d: δ 33.4
(s, 99.1%), 13.4 (s, 0.9%).
and evolving of a gas. Storage at –7 °C for several weeks gave a white
amorphous solid (228 mg, 0.14 mmol, 44%) and few crystals as colourless
blocks with a decomposition point of 178 °C. Except the X-ray diffraction
analysis the analytical data were obtained from the amorphous solid 7a.
Dimethylaminomethyl
mesityl
bis(trimethylsiloxy)phosphinium
iodide, [Me2NCH2(Mes)P(OSiMe3)2]I, (5·0.5 C7H8)
1H NMR (600.29 MHz, CD3CN): δ 1.96 (s, 2H, acetonitrile), 2.23 (s, 15H,
water), 2.28 (s, 24 H, N(CH3)2), 2.88 (d, 6J(1H–31P) = 3.6 Hz, 12H, CpCH3),
The reaction of the amine 3b (2.142 g, 7.95 mmol) with trimethyl iodosilane
(3.181 g, 15.90 mmol) in toluene solution (10 mL) at room temperature
gave the di-silylated phosphinium iodide 5·0.5C7H8 (4.039 g, 7.87 mmol,
99%) as colourless crystals as its toluene solvate within 15 minutes.
3.20 (d, J(1H–31P) = 3.2 Hz, 18H, CoCH3), 6.83 (d, J(1H–31P) = 3.9 Hz,
8H, CmH), 11.39 (not assigned).13C{1H} NMR (150.96 MHz, CD3CN): δ
21.0 (s, CpCH3), 23.7 (s, CoCH3), 47.8 (d, 3J(13C–31P) = 9 Hz, N(CH3)2),
57.6 (d, 1J(13C–31P) = 96 Hz, PCH2), 125.7 (d, 1J(13C–31P) = 138 Hz, Ci),
131.4 (d, 3J(13C–31P) = 14 Hz, Cm), 143.5 (d, 4J(13C–31P) = 3 Hz, Cp), 144.6
(d, 2J(13C–31P) = 12 Hz, Co). 19F{1H} NMR (564.78 MHz, CD3CN): δ –131.4
(s, ν1/2 = 153 Hz, 1J(19F–117/119Sn) = 1692 Hz, 51.4%), –123.5 (s, ν1/2 = 7 Hz,
1J(19F–117/119Sn) = 1718/1797 Hz, 0.6%), –119.3 (s, ν1/2 = 146 Hz, 1J(19F–
117/119Sn) = 1718 Hz, 47.8%). 31P{1H} NMR (242.99 MHz, CD3CN): 23.8 (s,
ν1/2 = 6 Hz, 2J(31P–117/119Sn) = 95 Hz). 119Sn{1H} NMR (223.68 MHz,
CD3CN): δ –792 (tqu, ν1/2 = 5 Hz, 1J(119Sn–19F) = 1744 Hz, 2J(119Sn–31P)
= 97 Hz, Sn(IV)), –405 (b, n1/2 = 27 kHz, Sn(II)). Elemental analysis for
C48H76F2I2N4O8P4Sn3 calcd. C 35.8, H 4.8, N 3.5; found C 33.5, 36.9, H
5.3, 5.6, N 3.1, 3.0. The variation of the values found experimentally reveal
that the amorphous material was not homogeneous. IR: 1024 (b), 1087 (s),
1451 (b), 1604 (s), 2922 (b), 3025 (b), 3411 (b).
4
4
1H NMR (400.25 MHz, CD3CN): δ 0.37 (s, 15H, Si(CH3)3, 2.32 (s, 3H,
CpCH3), 2.47 (bs, ν1/2 = 3.1 Hz, 6H, N(CH3)2), 2.56 (d, 4J(1H–31P) = 1.3Hz,
6H, CoCH3), 3.47 (d, 2J(1H–31P) = 5.3 Hz, 2H, PCH2N), 7.10 (d, 4J(1H–31P)
= 4.7 Hz, 2H, CmH). 13C{1H} NMR (100.65 MHz, CD3CN): δ 1.2 (s, OSiCH3),
21.2 (d, 5J(13C–31P) = 1.4 Hz, CpCH3), 23.7 (d, 3J(13C–31P) = 3.3 Hz,
CoCH3), 47.2 (d, 3J(13C–31P) = 9.0 Hz, N(CH3)2, 59.3 (d, 1J(13C–31P) = 113
Hz, PCH2), 132.5 (d, 3J(13C–31P) = 12.8 Hz, Co), 143.9 (d, 2J(13C–31P) =
12.8 Hz, Cm). The 13C{1H} NMR spectrum does not show the resonances
of Ci and Cp. 29Si{1H} NMR (119.26 MHz, CD3CN): δ 25.9, 26.0. 31P{1H}
NMR (242.99 MHz, CD3CN): δ 23.9 (s, 70.5%), 29.2 (bs, 1/2 = 24.3 Hz,
29.5%). Elemental analysis for C18H37INO2PSi2 calcd. C 42.1, H 7.3, N
2.7; found C 42.1, H 7.4, N 2.6. Due to hydrolysis under the conditions of
measurement just the first measurement is quoted. ESI MS (acetonitrile,
m/z, positive mode): 314 [MesP(O)(OSiMe3)CH2NMe2+H]+, 483
{2 [MesP(O)(OH)CH2NMe2]+H}+,
MesP(O)(OH)CH2NMe2 + H]+.
555
[MesP(O)(OSiMe3)CH2NMe2+
Acknowledgements
We are grateful to anonymous reviewers for valuable hints.
Dimethylammoniummethyl mesityl phosphinic acid iodide,
6·HI·CH2Cl2
Keywords: Phosphorus • tin • silicon • X-ray diffraction •
hydrogen bridge
Hydrolysis of the solution of compound 5 (857 mg, 1.67 mmol) in
acetonitrile with methanol (1 mL) and evaporation of the volatiles gives
compound 6 as amorphous solid (332 mg, 1.32 mmol, 79%). The latter
was crystallized from methanol, water and dichloromethane, respectively,
to give 2·6·HI·CH3OH, 6·0.5HI and 6·HI·CH2Cl2, respectively, as single
crystals which are suitable for x-ray diffraction analysis. The
dichloromethane solvate 6·HI·CH2Cl2 has a melting point of 217 °C
(decomposition). This material was used for the NMR and IR spectroscopic,
mass spectrometric, and elemental analyses reported below.
[1]
[2]
S. Demkowicz, J. Rachon, M. Dasko, W. Kozak, RSC Adv 2016, 6, 7101-
7112.
a) L. Maier, Phosphorus, Sulfur, and Silicon and the Related Elements
1992, 66, 67-72. b) A. Orthaber, J. H. Albering, F. Belaj, R. Pietschnig J.
Fluorine Chem. 2010, 131 1025–1031.
[3]
a) G. M. Kosolapoff, L. Maier (Hrsg.) Organic Phosphorus Compounds
Vol. 7, John Wiley & Sons, Inc., 1950; b) R. Rabinowitz, J. Org. Chem.
1963, 28, 2975-2978.; c) A. J. Rudinskas, R. L. Salvador, T. L. Hullar, J.
Org. Chem. 1977, 42, 2771- 2776.; d) G. M. Blackburn, D. Ingleson, J.
Chem. Soc., Perkin Trans. 1 1980, 1150-1153.; e) J. Zygmunt, P.
Kafarski, P. Mastalerz, Synthesis 1978, 1978, 609-612.
1H NMR (300.13 MHz, D2O): δ 2.29 (s, 3H, CpCH3), 2.64 (s, 6H, N(CH3)2),
3.03 (s, 6H, CoCH3), 3.67 (d, 2J(1H–31P) = 7.7 Hz, 2H, PCH2N(CH3)2), 7.00
(d, 4J(1H–31P) = 3.8 Hz, 2H, CmH). 13C{1H} NMR (75.48 MHz, D2O): δ 21.2
(s, CpCH3), 23.7 (d, 4J(1H–31P) = 3.0 Hz, CoCH3), 46.3 (d, 3J(13C–31P) = 4.7
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1
a) J. Chojnowski, M. Cypryk, J. Michalski, Synthesis 1978, 1978, 777-
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Hz, PCH2N(CH3)2), 58.1 (d, J(13C–31P) = 94.1 Hz, PCH2N(CH3)2), 125.9
(d, 1J(13C–31P) = 125.9 Hz, Ci), 132.2 (d, 3J(13C–31P) = 13.5 Hz, Cm), 144.4
(d, 4J(13C–31P) = 2.8 Hz, Cp), 144.4 (d, 2J(13C–31P) = 12.0 Hz, Co). 31P{1H}
NMR (121.50 MHz, D2O): δ 32.2. Elemental analysis for
C12H20NO2P·CH2Cl2·0.9HI calcd. C 35.4, H 5.2, N 3.2; found C 35.4, H 5.1,
N 3.5. By drying the compound 0.1 molar equivalents of HI were removed.
ESI MS (methanol, m/z, positive mode): 242 [6+H]+, 264 [6+Na]+, 505
[2·6+Na]+, 746 [3·6+Na]+, 768 [3·6–H+2Na]+, 790 [3·6–2H+3Na]+. ESI MS
(methanol, m/z, negative mode): 240 [6 – H]–. IR: P=O 1198 (s).
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Reaction of in situ generated 5 with SnF2 giving amorphous material
7a consisting of a compound of yet unknown structure and some
crystals of (SnI)2[{Me2NCH2 (Mes)P(O)2}4SnF2], 7
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To a stirred solution of compound 3b (350 mg, 1.30 mmol) in acetonitrile
(5 mL) at room temperature trimethyl iodosilane (177 µl, 1.30 mmol) was
added. After stirring the colourless reaction mixture for another 14 hours
the tin(II) fluoride (102 mg, 0.65 mmol) was added to give a yellow solution
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10.1002/ejic.201800343
European Journal of Inorganic Chemistry
FULL PAPER
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10.1002/ejic.201800343
European Journal of Inorganic Chemistry
FULL PAPER
FULL PAPER
Aryl(dimethylaminomethyl)phosphinic
acid ethyl esters,
Silicon Phosphorus Tin Chemistry
Michael Lutter, Klaus Jurkschat*
Ar(Me2NCH2)P(O)OEt (3a, Ar = Ph;
3b, Ar = mesityl) undergo ester clea-
vage with trimethyl iodosilane giving
the phosphinium iodide derivative 5
that in turn is in equilibrium with the
trimethyl-silyl ester 5a. With tin(II) hali-
des, ester cleavage accompanied by
redox-type reactions take place giving
mixed-valent dinuclear tin salts such
as 4·6CH2Cl2 and
Page No. – Page No.
Aryl(dimethylaminomethyl)phosphinic
Acid Esters. Syntheses, Structures,
and Reactions with Halogen
Hydrogen Acids, Tin Halides and
Trimethyl Halosilanes
((Insert TOC Graphic here: max.
width: 5.5 cm; max. height: 5.0 cm;
NOTE: the final letter height should
not be less than 2 mm.))
[{SnII Me2NCH2(Mes)P(O)2}4SnIVF2]I2,7.
2
This article is protected by copyright. All rights reserved.