Interaction of some methylenediphosphanes with hexafluoroacetone and hexafluorothioacetone dimer

Article abstract of DOI:10.1002/1099-0682(200109)2001:9<2377::AID-EJIC2377>3.0.CO;2-3

The reactions of methylenediphosphanes 1a-c with hexafluoroacetone (HFA) and hexafluorothioacetone dimer (HFTA) gave the respective carbodiphosphoranes 5a, 5b, 6, 15, and 19. The carbodiphosphoranes 6 and 19, with phenyl groups at phosphorus, were able to react further with C=O or C=S functions. Compound 6 added one equivalent of HFA across one of the ylidic P=C bonds to give compound 9, a stable intermediate of the Wittig reaction. The addition of HFTA to 19 gave, unexpectedly, the isomeric compound 21. The molecular structures of 9, 15, and 21 were confirmed by X-ray investigations.

Full text of DOI:10.1002/1099-0682(200109)2001:9<2377::AID-EJIC2377>3.0.CO;2-3

FULL PAPER
Interaction of Some Methylenediphosphanes with Hexafluoroacetone and
Hexafluorothioacetone Dimer
Igor V. Shevchenko,*[a] Rostislav N. Mikolenko,[a] Enno Lork,[b] and Gerd-
Volker Röschenthaler*[b]
Keywords: Phosphanes / Hexafluoroacetone / Hexafluorothioacetone / Ylides / Wittig reactions
The reactions of methylenediphosphanes 1a−c with hexa- across one of the ylidic P=C bonds to give compound 9, a
fluoroacetone (HFA) and hexafluorothioacetone dimer
(HFTA) gave the respective carbodiphosphoranes 5a, 5b, 6,
15, and 19. The carbodiphosphoranes 6 and 19, with phenyl
groups at phosphorus, were able to react further with C=O
or C=S functions. Compound 6 added one equivalent of HFA
stable intermediate of the Wittig reaction. The addition of
HFTA to 19 gave, unexpectedly, the isomeric compound 21.
The molecular structures of 9, 15, and 21 were confirmed by
X-ray investigations.
The mechanism probably involves the intermediate
formation of the unstable betaines 3a and 3b, which do not
add a second molecule of hexafluoroacetone to give 2a and
2b, but undergo a proton migration from the PϪCH2ϪP
unit to the secondary carbon of the hexafluoroisopropoxy
group forming the monoylides 4a and 4b. It is difficult to
detect these products by NMR spectroscopy at room tem-
perature since they react quickly with HFA to give the final
products 5a and 5b. Thus, the presence of the methylene
group with labile protons in the α-position to the phos-
phorus atoms is a necessary condition for this reaction.
Introduction
It is well-known that the reaction of hexafluoroacetone
(HFA) with phosphorus(III) derivatives can lead to the
formation of 1,3,2- or 1,4,2-dioxaphospholanes.[1Ϫ4] Re-
cently we found that the interaction of HFA with the
methylenediphosphanes 1a and 1b proceeds in a different
way to yield quantitatively the carbodiphosphoranes 5a and
5b,[5,6] but not the expected 1,3,2-dioxaphospholanes 2a and
2b (Scheme 1).
Results and Discussion
In order to answer the question as to whether this reac-
tion is an exception or it has more common character, we
decided to use the P-phenyl-substituted starting material
1c (Scheme 2).
Scheme 1
[a]
Institute of Bioorganic Chemistry,
Murmanskaya Str. 1, 02094 Kiev, Ukraine
Fax: (internat.) ϩ38-44/573-2552
E-mail: ishev@bpci.kiev.ua
[b]
Institute of Inorganic and Physical Chemistry,
University of Bremen, NW2 C2350
Leobener Straße, 28334 Bremen, Germany
Fax: (internat.) ϩ49-421/218-4267
E-mail: gvr@chemie.uni-bremen.de
Scheme 2
Eur. J. Inorg. Chem. 2001, 2377Ϫ2383
WILEY-VCH Verlag GmbH, 69451 Weinheim, 2001
1434Ϫ1948/01/0909Ϫ2377 $ 17.50ϩ.50/0
2377

I. V. Shevchenko, R. N. Mikolenko, E. Lork, G.-V. Röschenthaler
FULL PAPER
Like compounds 1a and 1b, the bis(diphenylphosphanyl-
methane) 1c reacts with HFA to give the respective carbodi-
phosphorane 6. After slow bubbling of gaseous HFA
through a solution of 1c in benzene at 20 °C, the 31P NMR
spectrum of the reaction mixture showed the presence of
only compound 6 as a singlet at δ ϭ 35.3. The 19F NMR
spectrum displays only a doublet at δ ϭ Ϫ72.45 (3JHF
ϭ
6.6 Hz) confirming the equivalence of the all fluorine atoms
and the presence of one proton in each HC(CF3)2 unit.
The carbodiphosphorane 6 is stable in solution at room
temperature for several hours and quickly decomposes in
the absence of the solvent. The decomposition of the molec-
ule proceeds analogously to that of 5a or 5b, and gives
methylene bis(difluorophosphorane) 7[6] and methylenedi-
phosphane oxide 8. It is interesting that the formation of
the dioxide 8 is not accounted for by the hydrolysis of the
Figure 1. Perspective view and labeling scheme for the molecule 9;
bisdifluorophosphorane 7, as the reaction was carried out selected bond lengths [pm] and angles [°]: P(1)ϪO(2) 162.16(19),
P(1)ϪC(1) 170.3(3), P(1)ϪC(12) 179.2(3), C(1)ϪP(2) 175.1(3),
under anaerobic conditions. The formation of the analog-
C(1)ϪC(2) 151.5(4), C(2)ϪO(1) 141.0(3), P(2)ϪO(1) 178.38(19),
ous dioxide was also observed for 5a and 5b.[6]
P(2)ϪO(3) 177.80(18), P(2)ϪC(24) 182.4(3); P(1)ϪC(1)ϪP(2)
130.10(15), C(1)ϪP(2)ϪO(1) 76.00(11), C(1)ϪC(2)ϪO(1) 96.1(2),
Unlike compounds 5a and 5b, the carbodiphosphorane 6
is able to add one more equivalent of HFA across one of
the ylidic PϭC bonds with the formation of the cyclic prod-
uct 9, which is poorly soluble and crystallizes from the reac-
tion mixture in good yield. It can be considered as a Wittig
reaction intermediate, which are usually unstable at room
temperature and cannot be isolated. Only a few compounds
of this type are known. For example, an analogous addition
has been observed for some other carbodiphos-
phoranes.[7Ϫ9] The proposed structure of compound 9 is in
C(2)ϪO(1)ϪP(2)
94.96(15),
C(2)ϪC(1)ϪP(2)
92.63(17),
C(2)ϪC(1)ϪP(2)ϪO(1) 3.97(14)
they were very unstable and we could isolate only the prod-
ucts of their decomposition.[6]
We think that cleavage of the C(2)ϪO(1) bond [141.0(3)
pm] is less preferable than that of the P(2)ϪO(1) bond, as
in the latter case it would form the more stable zwitterionic
structure 9a. The reversible cleavage of the PϪO bond of
the intermediate oxaphosphetanes has also been postulated
by other authors for the Wittig reaction mechanism.[10]
Indeed, heating compound 9 in chloroform or toluene
solution at 60Ϫ100 °C led to the completion of the Wittig
reaction, and gave a mixture of compounds 10Ϫ13
(Scheme 3), their relative amounts depending on the tem-
perature and the solvent used. Compound 10 was not stable
during the decomposition and was only detected by 31P
NMR spectroscopy as a singlet at δ ϭ 36. Compound 11
was isolated in low yield as a pure crystalline product. The
formation of two other products 12 and 13 can be ac-
counted for by the decomposition of the compounds 10 and
11, in accordance with our above-mentioned conclusion
about the formation of the dioxide 8. Compound 12 showed
two characteristic quadruplets for the two inequivalent CF3
groups in the 19F NMR spectra. Compound 13 was identi-
fied by comparison with a sample obtained independently.
1
accordance with 31P and H NMR spectroscopy; the two
different HC(CF3)2 groups display two characteristic mul-
tiplets at δ ϭ 3.21 and 4.36 in the 1H NMR spectrum. How-
ever, the 19F NMR spectrum displays an interesting peculi-
arity that may reflect the molecular structure of 9. The two
CF3 groups connected to the four-membered ring are
equivalent and display a common signal rather than the two
quadruplets that we observed earlier for an analogous com-
pound.[6] The equivalence of these CF3 groups could be a
result of the appropriate symmetry of the molecule: for ex-
ample, if the plane of symmetry were to coincide with the
four-membered cycle. However, the appearance of such
symmetry in this molecule is very unlikely. Another ex-
planation is that the four-membered cycle is open in solu-
tion, making the rotation of the (CF3)2C unit possible.
Looking for an answer to this question, we investigated this
compound by X-ray analysis (Figure 1).
This analysis showed that the molecule does not have a
plane of symmetry, which is why the equivalence of the CF3
groups in solution can be only explained by the cleavage of
one of the bonds of the four-membered ring. The ring is
strained, as the C(1)ϪP(2)ϪO(1) angle is only 76° (in crys-
talline form), which should promote its opening. Although
the C(1)ϪC(2) bond (152 pm) is somewhat longer then the
3
normal Csp2ϪCsp3 bond, and is closer to normal Csp3ϪCsp
bond lengths, its cleavage is unlikely, as this would result in
the formation of the carbene structure, which, according to
our previous results, should be unstable. We have already
tried to obtain phosphonium-substituted carbenes, however Scheme 3
2378
Eur. J. Inorg. Chem. 2001, 2377Ϫ2383

Interaction of Methylenediphosphanes with Hexafluoroacetone and -thioacetone Dimer
FULL PAPER
Thus, the substitution of the dialkylamino groups at
phosphorus in methylenediphosphanes 1a and 1b by phenyl
groups did not change the course of the reaction with HFA.
Our further interest was directed to the reaction of
methylenediphosphanes 1aϪc with HFTA, whose proper-
ties are somewhat different from that of HFA (e.g. it easily
dimerizes, and exists as a dimer at room temperature).[11]
Therefore, one could expect that the softer sulfur atom
might change the course of reaction (Scheme 1). However,
compound 1b and HFTA in hexane gave the carbodiphos-
phorane 15 quantitatively at Ϫ40 °C (Scheme 4). The 31P
NMR spectrum of the reaction mixture, taken immediately
after the addition of HFTA to 1b, displayed only one in-
tense singlet at δ ϭ 41.22 (similar to the chemical shift value
found for 5b), indicating two magnetically equivalent phos-
phorus nuclei of 15. A two-step reaction is proposed with
the intermediate formation of the mono ylide 14, which was
detected in the reaction mixture by 31P NMR spectroscopy
as two doublets at δ ϭ 67.4 and 74.7 (2JPP ϭ 61 Hz) when
only one equivalent of HFTA was added to the starting
material.
Figure 2. Perspective view and labeling scheme for the molecule 15
(H atoms are omitted for clarity); selected bond lengths [pm] and
angles [°]: P(1)ϪN(1) 167.32(12), P(1)ϪC(1) 162.57(15), C(1) ϪP(2)
162.60(15), P(1)ϪS(1) 217.60(5), S(1)ϪC(2) 180.40(16), N(1)ϪC(5)
147.81(19), C(2)ϪC(3) 152.1(2); C(1)ϪP(1)ϪN(1) 122.84(7),
C(1)ϪP(1)ϪS(1)
N(1)ϪP(1)ϪS(1)
108.73(5),
98.12(5),
N(1)ϪP(1)ϪN(2)
P(1)ϪC(1)ϪP(2)
101.47(6),
139.52(9),
P(1)ϪS(1)ϪC(2) 101.81(5)
Unlike allenes[12] and heteroallenes, in which the angle
between the two double bonds is about 180°, the PϭCϭP
angle in carbodiphosphoranes lies in the range 117Ϫ150°,
depending on the structure and packing effects.[13Ϫ17] The
only exception is hexa(dimethylamino)carbodiphosphorane,
which has a linear structure and D3d symmetry.[18] Here, the
PϭCϭP angle of carbodiphosphorane 15 is 139.5° with a
PϭC bond length of 162.57 pm. Both phosphorus atoms
of compound 15 have significantly distorted tetrahedral
symmetry, with the largest deviation from the ideal angle
Scheme 4
The carbodiphosphorane 15 turned out to be less stable being 13.3°. It is interesting that because of the low sym-
than its oxygen analog 5b. It decomposed in hexane solu- metry of the molecule in the solid state the ethyl groups of
tion at room temperature after several hours, whereas car- the diethyl substituents and CF3 groups of the hexafluoro-
bodiphosphorane 5b was stable for two days under the same isopropoxy units are not equivalent. In solution, however,
conditions. The choice of hexane as a solvent is very im- these groups are equivalent and have equal spectral charac-
portant for this reaction as in other solvents compound 15 teristics. For example, all fluorine nuclei display a doublet
is not stable or its synthesis may be accompanied by the at δ ϭ Ϫ67.7 (3JHF ϭ 8.14 Hz) in the 19F NMR spectra,
formation of by-products. The decomposition of 15 gave a which means that in a solution of 15 there is either a rota-
complex mixture with the predominant product being tion or a rapid flip-flop movement around the PϪCϪP
methylenebis(difluorophosphorane) 16. This product was bonds.
previously isolated after the decomposition of 5b and
showed the same signal in the 31P NMR spectrum of a trip- acids: for example, with HCl or HBF4 it gives the corres-
let at δ ϭ Ϫ52.2 (1JFP ϭ 728 Hz).[6]
ponding colorless salts 17 and 18 (Scheme 5). As was to be
The carbodiphosphorane 15, as a strong base, reacts with
Despite the reduced stability of carbodiphosphorane 15, expected, the positive charge of the cation is delocalized
it was possible to isolate it in a crystalline form, although over the PϪCϪP triad, resulting in the magnetic equival-
all our efforts to obtain crystals of the more stable oxygen ence of the phosphorus nuclei. The 31P NMR spectra of
derivative 5b failed. Colorless crystals of compound 15 can compounds 17 and 18 show only one singlet at δ ϭ 62 and
be stored at Ϫ25 °C, however they turn yellow and slowly 68, respectively. The analogous salts have been obtained
decompose at room temperature. The X-ray analysis of 15 earlier for carbodiphosphoranes 5a and 5b, and showed the
showed the following molecular structure (Figure 2).
same spectroscopic data.[5] The chloride 17, however, differs
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I. V. Shevchenko, R. N. Mikolenko, E. Lork, G.-V. Röschenthaler
FULL PAPER
from its oxygen derivative. After the addition of HCl to a significantly narrower (129.2° versus 139.5°). The angles be-
solution of 15 in hexane compound 17 immediately precip- tween the phosphorus atoms bonds become closer to those
itates from the reaction mixture as a colorless crystalline for a tetrahedral geometry. The PϪCϪP bond lengths of 18
product that is insoluble in non-polar solvents. This prod- are larger than those of 15 [169.6(4) versus 162.57(15) pm].
uct is stable at room temperature in the solid state. How- However, the other bonds at the phosphorus atoms are
ever, the dissolution of this compound leads to its trans- shorter in 18 than in 15. The largest difference (4.9 pm) was
formation (slowly in [D8]toluene and rapidly in CDCl3) into found for the PϪS bonds, which may indicate the possible
another product, which shows two doublets at δ ϭ 62.7 and participation of the sulfur atoms in delocalization of the
71.1 (2JPP ϭ 42.6 Hz) in the 31P NMR spectrum. Since the positive charge.
analogous oxygen derivatives are stable in symmetrical
The interaction of the dimer of HFTA with methylene-
form,[5] the decomposition of 17 can only be explained by bis(diphenylphosphane) 1c turned out to be quite unusual.
the presence of sulfur atoms and by the nucleophilicity of The first phase of this reaction, the addition of the two
the chlorine anion. Although the appearance of substantial HFTA units to 1c, does not differ from the analogous reac-
amounts of by-products was not observed in the 31P NMR tion with HFA and gives carbodiphosphorane 19
spectra, we could not isolate the unknown product in a (Scheme 6). Unlike carbodiphosphoranes 5, 6, and 15,
crystalline form and investigate it more thoroughly.
which are relatively stable in solution at room temperature,
compound 19 exists in diethyl ether solution only at Ϫ70
°C and can be detected spectroscopically only at this tem-
perature. There is no doubt about the symmetrical structure
of this compound as the 31P NMR spectrum at this temper-
ature shows only one intense singlet at δ ϭ 22.5. The oxy-
gen derivative 6 displays similar spectroscopic data. At Ϫ40
°C the carbodiphosphorane 19 decomposes completely in
solution within 30Ϫ40 min.
Scheme 5
In contrast to the chloride anion, the tetrafluoroborate is
less nucleophilic and the corresponding salt 18 was stable
and did not decompose even in boiling CDCl3 solution.
This compound crystallized easily allowing us to establish
its structure by X-ray analysis (Figure 3).
Scheme 6
In contrast to carbodiphosphorane 6, which reacts fur-
ther with HFA very slowly at room temperature, carbodi-
phosphorane 19 is very active and easily reacts even at low
temperature (Ϫ70 °C) with HFTA. However, the character
of this interaction is not quite clear. If 1.5 equivalents of
the dimer of HFTA were added to the methylenediphos-
phane 1c the reaction mixture only showed two doublets in
the 31P NMR spectrum at δ ϭ 65.2 and Ϫ4.5, with a coup-
ling constant of 185.3 Hz. The same spectroscopic data
were found for the colourless crystalline product that was
isolated from the reaction mixture in good yield. We were
sure that this was the cyclic product 20, which is analogous
to compound 9. However, the 19F NMR spectrum showed
the presence of only two fragments of HFTA in the molec-
Figure 3. Perspective view and labeling scheme for the molecule
18; selected bond lengths [pm] and angles [°]: P(1)ϪN(1) 163.6(3),
P(1)ϪC(1) 169.6(4), C(1) ϪP(2) 169.7(4), P(1)ϪS(1) 212.72(14),
S(1)ϪC(10) 182.5(4), N(1)ϪC(2) 148.2(5), C(10)ϪC(11) 152.2(6);
C(1)ϪP(1)ϪN(2)
N(1)ϪP(1)ϪS(1)
116.21(19),
107.61(13),
C(1)ϪP(1)ϪS(1)
N(1)ϪP(1)ϪN(2)
111.42(14),
108.99(17),
P(1)ϪC(1)ϪP(2) 129.2(2), P(1)ϪS(1)ϪC(10) 111.86(15)
The addition of one proton to the PϭCϭP carbon atom ule. Beside this, the mass spectrum together with the analyt-
of 15 leads to certain changes in the geometry of the prod- ical data pointed to a molecular weight of 748.56, the same
uct. As one would expect, the PϪCϪP angle in 18 becomes as in carbodiphosphorane 19. The X-ray analysis solved
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Interaction of Methylenediphosphanes with Hexafluoroacetone and -thioacetone Dimer
FULL PAPER
1
The digital resolutions were 0.25 Hz, 0.5 Hz, and 1.25 Hz for H,
13C, and 31P NMR spectra, respectively.
this puzzle and gave structure 21 (Figure 4) which is the
constitutional isomer of compound 19.
Synthesis of Compound 6: A solution of methylenebis(diphenylpho-
sphane) 1c (30 mg, 0.078 mmol) in [D6]benzene (0.5 mL) was
placed in a tube with diameter 4Ϫ5 mm (a 5 mm NMR tube can
be used) and 3.8 mL (0.172 mmol) of gaseous HFA were slowly
bubbled through it at room temperature using a syringe with a thin
needle. The end of the needle was placed at the bottom of the tube.
The reaction mixture showed the following spectral parameters: 1H
3
NMR (89.56 MHz, C6D6): δ ϭ 6.27 [br. sept., JHF ϭ 6.58 Hz, 2
H, HC(CF3)2], 6.95 (m, 12 H, Ph), 7.70 (m, 8 H, Ph). Ϫ 19F NMR
3
(84.26 MHz, C6D6): δ ϭ Ϫ72.46 (d, JHF ϭ 6.58 Hz, 12 F, CF3).
Ϫ
31P NMR (36.2 MHz, C6D6): δ ϭ 35.3 (s, 2P).
Synthesis of Compound 9: Gaseous hexafluoroacetone (19 mL,
0.832 mmol) was condensed into a solution of methylenebis(di-
phenylphosphane) 1c (100 mg, 0.260 mmol) in benzene (1 mL) in a
glass tube. The tube was sealed and kept at room temperature for
3 days. According to the NMR spectroscopic data the reaction was
complete in 30 h, and the rest of the time was needed for the crys-
tallization of the product as a colorless crystals. The crystals were
filtered off, washed with 0.4 mL of dichloromethane and dried in
vacuo 0.05 mm. Yield 145 mg (63%), m.p. 121Ϫ124 °C. Ϫ 1H
3
NMR (89.56 MHz, CDCl3): δ ϭ 3.57 [d. sept., JPH ϭ 10.6 Hz,
Figure 4. Perspective view and labeling scheme for the molecule
21; selected bond lengths [pm] and angles [°]: P(1)ϪC(1) 181.4(5),
C(1)ϪP(2) 170.4(5), P(2)ϪS(2) 215.55(19), C(1)ϪS(1) 176.8(5),
P(1)ϪC(5) 183.1(5), P(2)ϪC(20) 181.3(5); P(1)ϪC(1)ϪP(2)
117.6(3), C(1)ϪP(1)ϪC(5) 106.2(2), P(1)ϪC(1)ϪS(1) 125.5(3),
3
3JFH ϭ 6.6 Hz, 1 H, CH(CF3)2], 4.72 [d. sept., JPH ϭ 13.2 Hz,
3JFH ϭ 5.6 Hz, 1 H, CH(CF3)2], 7.25Ϫ8.12 (m, 20 H, Ph). Ϫ 19F
3
NMR (84.26 MHz, CDCl3): δ ϭ Ϫ70.98 (d, JFH ϭ 6.6 Hz, 6 F,
CF3), Ϫ72.26 (s, 6 F, CF3), Ϫ74.39 (s, 6 F, CF3). Ϫ 31P NMR
(36.2 MHz, CDCl3): δ ϭ Ϫ32.5 (d, 2JPP ϭ 56.0 Hz), 58.8 (d, 2JPP ϭ
56.0 Hz). Ϫ C34H22F18O3P2 (882.46): calcd. C 46.28, H 2.51; found
C 46.26, H 2.53.
P(2)ϪC(1)ϪS(1)
113.4(3),
C(1)ϪP(2)ϪS(2)
117.22(18),
C(1)ϪP(2)ϪC(20) 116.0(2)
These two isomers exist independently from each other
and do not interconvert. Carbodiphosphorane 19 is un-
stable and decomposes with the formation of a mixture of
compounds that does not contain signals of the other iso-
mer. Thus, in order to transform the symmetric carbodi-
phosphorane 19 into its asymmetrical isomer 21 the pres-
ence of HFTA is necessary. HFTA most likely plays a cata-
lytic role in this process. However in this case it is not clear
why the same yield of 21 cannot be obtained with only a
small excess of HFTA.
Synthesis of Compound 11: A solution of compound 9 (100 mg,
0.113 mmol) in toluene (1 mL) was heated at 100 °C for 5 h. The
solvent was removed in vacuo (0.05 mm), the remaining oil was
dissolved in boiling hexane and the solution was left at 20 °C over-
night. A mixture of compounds 11Ϫ13 with predominant content
of 11 was separated, and the mother liquid was kept for two weeks
at 20 °C followed by two weeks at Ϫ20 °C. Colourless crystals of
11 (7 mg, 16%) were separated from the precipitated oil and dried
in vacuo. Ϫ 1H NMR (89.56 MHz, CDCl3): δ ϭ 5.41 [d. sept.,
3JPH ϭ 12.29 Hz, JFH ϭ 5.86 Hz, 1 H, CH(CF3)2], 7.35Ϫ7.95 (m,
3
It is interesting to note that the value of the 2JPP coupling
constant of compounds containing the PϪCϪP system may
vary in the range from less then 1 Hz to over 100 Hz. The
2JPP coupling constant of the compound 21 was unusually
large 185 Hz. However, the largest value of this constant
has been recently reported for 1σ4,3σ2-diphosphaallene.[19]
Although, to the best of our knowledge, this unusual iso-
merization does not have direct analogies in the literature,
it may be related to other migration processes observed for
phosphorus compounds.[19,20]
10 H, Ph). Ϫ 19F NMR (84.26 MHz, CDCl3): δ ϭ Ϫ73.96 (d,
3JFH ϭ 5.86 Hz, 6 F, CF3). Ϫ 13C NMR (22.5 MHz, CDCl3): δ ϭ
2
2
68.33 [d. sept., JPC ϭ 4.8 Hz, JFC ϭ 35.1 Hz, 1 C, CH(CF3)2],
120.4 (d, 1JPC ϭ 274.9 Hz, 2 C, Ph), 128.5 (d, 2JPC ϭ 14.7 Hz, 4 C,
Ph), 131.2 (d, 3JPC ϭ 11.7 Hz, 4 C, Ph), 132.95 (d, 4JPC ϭ 2.9 Hz, 2
C, Ph),. Ϫ 31P NMR (36.2 MHz, CDCl3): δ ϭ 39.85 (s, 2 P). Ϫ
C15H11F6OP2 (368.22): calcd. C 48.93, H 3.01; found C 48.21, H
3.13.
Synthesis of Compounds 12 and 13: A solution of compound 9
(150 mg, 0.170 mmol) in chloroform (1.5 mL) was heated to 60 °C
for 48 h and then the solvent was removed in vacuo (0.05 mm).
Crystallization of the residue from dichloromethane/hexane gave a
mixture of two types of crystals for compounds 12 and 13 (24 mg),
which were mechanically separated.
Experimental Section
12: Ϫ 1H NMR (89.56 MHz, CDCl3): δ ϭ 7.37 (d, 2JPH ϭ 11.6 Hz,
1 H), 7.44Ϫ7.92 (m, 10 H, Ph). Ϫ 19F NMR (84.26 MHz, CDCl3):
δ ϭ Ϫ65.7 (q, 4JFF ϭ 7.33 Hz, 3 F, CF3), Ϫ59.1 (q, 4JFF ϭ 7.33 Hz,
3 F, CF3). Ϫ 31P NMR (36.2 MHz, CDCl3): δ ϭ 17.1 (s, 2 P).
All operations were performed under nitrogen in a glove box. The
solvents were dried by standard procedures. Ϫ The NMR spectra
were measured with a JEOL FX-90Q, Bruker DPX 200 or Bruker
1
AMX 360 spectrometer. The H and 13C chemical shifts are refer-
enced to tetramethylsilane (TMS). The 31P chemical shifts were 13: Ϫ 1H NMR (89.56 MHz, CDCl3): δ ϭ 7.28Ϫ7.90 (m, 10 H,
measured using 85% aqueous orthophosphoric acid as an external
standard. As usual, high frequency shifts are given positive signs.
Ph), 8.81 (br. s, 1 H) Ϫ 31P NMR (36.2 MHz, CDCl3): δ ϭ 26.5
(s, 2 P).
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2
Synthesis of Compound 15:
A
solution of HFTA (50 mg, 3JHH ϭ 7.06 Hz, 24 H, NCH2CH3), 1.91 (t, JPH ϭ 4.9 Hz, 1 H,
3
0.137 mmol) in hexane (1.2 mL), cooled to Ϫ40 °C, was quickly
added to a solution of methylenebis[bis(diethylamino)phosphane]
1b (50 mg, 0.137 mmol) in hexane (1.2 mL) at the same temper-
ature. The reaction mixture was stirred at Ϫ20 °C for 5 min. and
then kept at this temperature for 20 min. The colorless crystalline
product 16 was filtered off and dried in vacuo. Yield of the crystals
48 mg (48%). According to the 31P NMR spectrum the mother
liquor contained compound 15 only. Ϫ 1H NMR (360.13 MHz,
C6H14): δ ϭ 1.33 (t, 1JHH ϭ 7.1 Hz, 24 H, CH2CH3), 3.33 (m, 16 H,
CH2CH3), 5.02 [sept, 2 H, CH(CF3)2]. Ϫ 19F NMR (188.31 MHz,
PϪCHϪP), 3.27 (m, 16 H, NCH2CH3), 4.25 [br. sept., JFH
ϭ
7.1 Hz, 2 H, HC(CF3)2]. Ϫ 19F NMR (188.31 MHz, CDCl3): δ ϭ
Ϫ69.5 (d, 3JHF ϭ 7.1 Hz, 12 F, CF3), Ϫ151.2 (s, BF4). Ϫ 31P NMR
(145.78 MHz, CDCl3): δ ϭ 68.2 (s, 2 P). Ϫ C23H43BF16N4P2S2
(816.48): calcd. C 33.83, H 5.31; found C 33.71, H 5.02.
Synthesis of Compound 21: A solution of thiohexafluoroacetone
(72 mg, 0.198 mmol) in ether (2 mL) was cooled to Ϫ70 °C and
quickly added to a solution of methylenebis(diphenylphosphane)
1c (50 mg, 0.130 mmol) in ether (3 mL) at the same temperature.
The reaction mixture was stirred at Ϫ70 °C for 10 min. The reac-
tion solution was then concentrated to a volume of about 0.6 mL.
Hexane (1 mL) was added and solution was kept at Ϫ25 °C for 3
days. The colourless crystalline product formed over this time was
3
C6H14): δ ϭ Ϫ67.7 (d, JHF ϭ 8.14 Hz, 12 F, CF3). Ϫ 31P NMR
(145.78 MHz, C6H14): δ ϭ 41.4 (s, 2 P). Ϫ C23H42F12N4P2S2
(728.67): calcd. C 37.91, H 5.81; found C 37.57, H 5.79.
Synthesis of Compound 18: The reaction mixture of the carbodipho- filtered off and dried in vacuo. Yield of the crystals 50 mg (50%).
sphorane 15 obtained as described above was diluted with hexane
(2 mL) and warmed to 20 °C. At this temperature the crystals of
15 dissolved completely. The solution was then quickly cooled to
Ϫ20 °C and the equivalent amount of HBF4 (solution in ether)
was added to it. The colourless crystalline product that precipitated
According to the 31P NMR spectrum the mother liquid contained
1
compound 21 only. Ϫ H NMR (360.13 MHz, CDCl3): δ ϭ 3.20
3
3
[sept., JFH ϭ 8.07 Hz, 1 H, CH(CF3)2], 4.36 [d. sept., JFH
ϭ
3
7.34 Hz, JPH ϭ 1.98 Hz, 1 H, CH(CF3)2], 6.85Ϫ7.18 (m, 12 H,
Ph), 7.78Ϫ8.08 (m, 8 H, Ph). Ϫ 19F NMR (188.31 MHz, CDCl3):
3
immediately was filtered off and dried in vacuo. Yield 98 mg (88%); δ ϭ Ϫ66.15 (dd, JHF ϭ 7.4 Hz, JPF ϭ 2.6 Hz, 6 F, CF3), Ϫ65.75
3
after crystallization from CH2Cl2/diethyl ether at Ϫ25 °C the yield
(d, JHF ϭ 7.4 Hz, 6 H, CF3) Ϫ 31P NMR (145.78 MHz, CDCl3):
is 61% (68 mg). Ϫ 1H NMR (360.13 MHz, CDCl3): δ ϭ 1.20 (t, δ ϭ Ϫ4.5 (d, 2JPP ϭ 185 Hz, 1 P, PϪCϪP), 65.2 (d, 2JPP ϭ 185 Hz,
Table 1. Crystal data and structure refinement parameters of compounds 9, 15, 18, 21
9
15
18
21
Formula
C34H22F18O3P2
C23H42F12N4P2S2
C23H43BF16
N4P2S2
816.48
C31H22F12P2S2
x 1/2 C4H10O
785.57
Mol. wt.
882.46
728.67
Temperature K
Wavelength pm
Crystal size [mm]
Crystal system
Space group
a [pm]
b [pm]
c [pm]
α [°]
173(2)
71.073
173(2)
71.073
173(2)
71.073
173(2)
71.073
0.6 ϫ 0.4 ϫ 0.3
Monoclinic
C2/c
1826.7(5)
948.75(11)
3989.7(6)
90
0.8 ϫ 0.6 ϫ 0.5
Monoclinic
Cc
2162.7(2)
1030.60(10)
1799.4(2)
90
0.6 ϫ 0.4 ϫ 0.3
Monoclinic
P21/n
1151.8(3)
1798.8(3)
1730.8(3)
90
1.0 ϫ 0.5 ϫ 0.3
Monoclinic
P21/n
1675.8(4)
1083.0(2)
1917.0(2)
90
β [°]
6.83(1)
90
3.3475(6)
8
1.716
0.263
2.52 to 25.00
3536
123.420(10)
90
3.3475(6)
4
1.446
0.343
96.14(2)
90
3.5654(13)
4
1.521
0.346
96.86(2)
90
3.4542(11)
4
1.501
0.337
γ [°]
V [nm3]
Z
Dcalcd. [Mg/m3]
Absorption coefficient [mmϪ1
2θ range [°]
F(000)
]
2.71 to 27.51
1512
2.26 to 25.00
1680
2.55 to 22.49
1576
Index range
Ϫ21 Յ h Յ 21,
Ϫ1 Յ k Յ 11,
Ϫ47 Յ l Յ 47
13731
Ϫ28 Յ h Յ 28,
Ϫ1 Յ k Յ 13,
Ϫ23 Յ l Յ 18
8241
Ϫ11 Յ h Յ 13,
Ϫ1 Յ k Յ 21,
Ϫ20 Յ l Յ 20
7844
Ϫ18 Յ h Յ 1,
Ϫ11 Յ k Յ 1,
Ϫ20 Յ l Յ 20
5706
Reflections collected
Independent reflections
Completeness to θmax
Max. and min. transmission
Data/Restraints/Parameter
Goodness-of-fit on F2
6012 [R(int) ϭ 0.0432] 7255 [R(int) ϭ 0.0161]
6235 [R(int) ϭ 0.0294] 4477 [R(int) ϭ 0.0471]
99.9
99.8
99.2
99.0
0.9251 and 0.8579
6012/0/517
0.8472 and 0.7709
7255/2/401
0.9033 and 0.8193
6235/0/446
0.9056 and 0.7292
4477/1/462
1.020
1.040
1.024
1.033
R1 ϭ 0.0448,
wR2 ϭ 0.1021
0.427 and Ϫ0.462
R1 ϭ 0.0249,
wR2 ϭ 0.0655
0.330 and Ϫ0.225
R1 ϭ 0.0677,
wR2 ϭ 0.1687
0.827 and Ϫ0.832
R1 ϭ 0.0544,
wR2 ϭ 0.1276
0.368 and Ϫ0.388
The solvent molecule
is disordered.
Ϫ
Final R indices [I Ͼ 2σ(I)]
Largest difference peak and
Ϫ3
˚
hole [e·A
]
Absolute structure parameter
Ϫ
0.44(3)
Ϫ
The structure was refined
as a merohedric twin
2382
Eur. J. Inorg. Chem. 2001, 2377Ϫ2383

Interaction of Methylenediphosphanes with Hexafluoroacetone and -thioacetone Dimer
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[4]
X-ray Crystal Structure Determination of Compounds 9, 15, 18, and
21: All crystallographic measurements were performed at 173(2) K
on a Siemens P4 diffractometer, using graphite monochromated
Mo-Kα radiation (λ ϭ 71.073 pm) and an LT2 low temperature
device. The structures were solved by direct methods and refined
by full-matrix least-squares on F2 using SHELX-97 (Sheldrick,
1997). All non-hydrogen atoms were refined anisotropically and the
position of the hydrogen atoms were calculated using a riding
model. Crystal data, data collection and processing parameters are
given in Table 1.
[5]
[6]
[7]
[8]
[9]
[10]
Crystallographic data (excluding structure factors) for the struc-
tures reported in this paper have been deposited with the Cam-
bridge Crystallographic Data Center as supplementary publication
nos. CCDC-150573 (9), CCDC-150574 (15), CCDC-150575 (18),
and CCDC-150576 (21). Copies of the data can be obtained
free of charge on application to CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK [Fax: (internat.) ϩ44-1223/336-033;
E-mail: deposit@ccdc.cam.ac.uk].
[11]
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We thank the Deutsche Forschungsgemeinschaft for financial sup-
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the MS measurements and Peter Brackmann for his assistance in
the X-ray structure analyses.
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Received November 15, 2000
[I00435]
Eur. J. Inorg. Chem. 2001, 2377Ϫ2383
2383