284
Russ.Chem.Bull., Int.Ed., Vol. 50, No. 2, February, 2001
Gololobov et al.
Table 3. Principal topological characteristics at the critical point
(3, 1) for a number of bonds in molecule 10c according to the
data from B3LYP/6-31G* quantum-chemical calculations
Table 4. Data from elemental analysis
Com-
poundCalculated
Found
Molecular
(%)
formula
Bond
ρ(r)
∇2ρ(r)
ε*
Ñ
Í
N
S
Hg
a.u.
6
24.93 5.01
25.03 4.87
53.02 6.87 3.89
52.75 6.64 3.85
48.19 6.10 3.49
48.19 5.81 3.51
42.71 6.15 2.65 13.80
44.35 6.13 3.04 13.93
40.99 5.18 2.56 11.90
40.91 5.15 2.65 12.13
46.32
46.47
C9H21Cl2HgP
C16H24Cl2NPS
Ñ(7)S(1)
N(1)C(7)
N(1)C(1)
P(1)C(7)
0.21
0.36
0.31
0.17
0.21
0.91
0.99
0.43
0.06
0.22
0.03
0.08
10a
10b
11
12
8.79
8.80
8.23
8.04
C16H23Cl3NPS
* ε Ellipticity.
C17H28Cl2NO3PS2
C18H27Cl2F3NO3PS2
model molecule 10c are characterized by negative ∇2ρ
values in spite of the substantial positive charge on the P
atom, which is typical of covalent interactions (Table 3).
Comparison of the ellipticities in the N(1)C(7)S(1)P(1)
fragment demonstrated that these values for the
N(1)C(1), S(1)C(7), and P(1)C(7) bonds are small,
whereas its value for the N(1)C(7) bond (0.22) is
comparable with the corresponding value for the phenyl
ring (0.25).
Therefore, in spite of the conclusion about the one-
and-a-half order of the N(1)C(7) and S(1)C(7)
bonds, which was made based on comparison of the
geometric parameters of compounds 10a and 10b and of
compounds 11 and 12, the topological analysis demon-
strated that the double bond in the zwitterionic com-
pounds is essentially localized and, consequently, as has
been noted previously,18 the bond lengths in organome-
tallic compounds are invariant with respect to fine elec-
tronic effects and not always can be used for the analysis
of delocalization.
Analysis of the crystal packings demonstrated that
the molecules are linked in dimers in all crystals under
study through strong secondary intermolecular Cl...Cl
interactions (Cl...Cl, 3.420(2)3.514(2) Å; CCl...Cl,
156.41(5)171.18(8)°). In the crystal of 11, there is also
a strong intermolecular N(1)H(1N)...O(1) hydrogen
bond between the basic molecule and the counterion.
Therefore, the importance of zwitterion 1a and struc-
turally similar adducts1 is determined both by their
reactivities and the reactivities of phosphines formed
upon decomposition of the former. In the latter case,
zwitterion 1a serves as a source of triisopropylphosphine,
which is of particular practical interest because it is
much easier to handle with stable crystalline zwitterion
1a than with triisopropylphosphine or other tertiary
phosphines.
Zwitterion 1a was prepared according to a procedure re-
ported previously.2
The reaction of zwitterion 1a with MeI. Zwitterion 1a (1 g,
3.51 mmol) was mixed with MeI (30 mL). After 3 h, the
precipitate that formed was filtered off, washed with ether, and
crystallized from a 1 : 5 CH2Cl2 : THF mixture. Less soluble
salt 5 was obtained in a yield of 120 mg, m.p. >260 °C.
31P NMR (CDCl3), δ: 46.68 (cf. lit. data6 for salt 5:
m.p. >360 °C, δP 46.3). 1H NMR (CDCl3), δ: 1.48 (dd, 18 H,
CH3CH, 3JHH = 7.2 Hz, 3JHP = 9.2 Hz); 2.00 (d, 3 H, CH3P,
JHP = 12.4 Hz); 2.97 (m, 3 H, CHCH3). The filtrate was
concentrated. The residue was recrystallized from acetone. Salt
4 was obtained in a yield of 0.54 g, m.p. 138140 °C. 31P NMR
(CDCl3), δ: 46.15 (cf. lit. data2 for compound 4: m.p.
139140 °C).
The adduct of triisopropylphosphine with mercuric chloride
(6). A solution of HgCl2 (480 mg, 1.75 mmol) in MeCN (3 mL)
was added to a solution of zwitterion 1a (500 mg, 1.75 mmol) in
MeCN (3 mL). After 15 min, the precipitate that formed was
filtered off and crystallized from CH2Cl2. The yield was 600 mg
(80%), m.p. 232235 °C. 31P NMR (acetone-d), δ: 78.49
1
(1JPHg = 1720 Hz). H NMR (acetone-d), δ: 1.47 (dd, 18 H,
3
3
CH3CH, JHH = 7.2 Hz, JHP = 9.2 Hz); 3.11 (m, 3 H,
CHCH3).
Zwitterions 10a,b. A. A twofold excess of isothiocyanate 9a
or 9b was added to a solution of zwitterion 1a in CH2Cl2. After
25 days, ether was added and the precipitate that formed was
filtered off and crystallized from acetone.
N-(2,6-Dichlorophenyl)triisopropylphosphoniothiocarbonyl-
amide (10a). The yield was 90%, m.p. 127142 °C (with
decomp.). 31P NMR (CDCl3), δ: 31.39. H NMR (CDCl3),
1
δ: 1.57 (dd, 18 H, CH3CH, 3JHH = 7.2 Hz, 3JHP = 15.2 Hz);
3.11 (m, 3 H, CHCH3); 6.89 (t, 1 H, Ph, 3JHH = 8.0 Hz); 7.27
(d, 2 H, Ph, 3JHH = 8.0 Hz).
N-(2,4,6-Trichlorophenyl)triisopropylphosphoniothiocar-
bonylamide (10b). The yield was 89%, m.p. 120136 °C (with
decomp.). 31P NMR (CDCl3), δ: 31.85. H NMR (CDCl3),
1
δ: 1.55 (dd, 18 H, CH3CH, 3JHH = 7.2 Hz, 3JHP = 15.2 Hz);
3.09 (m, 3 H, CHCH3); 7.27 (s, 2 H, Ph).
Experimental
B. A solution of zwitterion 1a (0.3 g, 1.0 mmol) and
2,6-dichlorophenyl isothiocyanate (0.36 g, 1.75 mmol) in tolu-
ene (1 mL) was heated at 8090 °C for 5 h. The reaction
mixture was cooled and the precipitate that formed was filtered
off, washed with a 1 : 1 etheracetone mixture, and crystallized
from acetone. The yield was 0.34 g (85%), m.p. 127142 °C
(with decomp). The NMR spectral data are analogous to those
reported above.
The NMR spectra were recorded on a Bruker AMX-400
1
spectrometer (400.26 MHz for H and 162.02 MHz for 31P)
relative to Me4Si and 80% H3PO4 for 1H and 31P, respectively.
The reactions were performed under an atmosphere of dry
nitrogen. The solvents were thoroughly purified and dried be-
fore use. The data from elemental analysis are given in Table 4.