Inorganic Chemistry
Article
(d, J = 6.0 Hz). 31P NMR (CDCl3, 120 MHz) δ = −26.02. HRMS
(ESI): m/z [M]+ calcd for C9H21N4ClP+ 251.1187; found: 251.1186.
ClP(iBuNCH2CH2)3N][Cl] (1b-Cl+·Cl−) (Known Compound).67
White solid; yield: 47% (206 mg); mp 125−127 °C. IR/cm−1:
3379, 2958, 2827, 1668, 1651, 1466, 1388, 1282, 1111, 1077, 1057,
869, 774, 573. 1H NMR (CDCl3, 300 MHz) δ = 3.63 (td, J = 3.0 Hz,
6.0 Hz, 6H), 3.34 (dt, J = 6.0 Hz, 12.0 Hz, 6H), 3.12 (dd, J = 6.0 Hz,
15.0 Hz, 6H), 2.01 (sept, J = 6.0 Hz, 3H), 0.93 (d, J = 6.0 Hz, 3H).
13C NMR (CDCl3, 75 MHz) δ = 59.6 (d, J = 2.2 Hz), 46.1 (d, J = 9.0
CONCLUSION
■
In this work, we have reported the synthesis of five different
chloroazaphosphatranes with PF6 as a counterion. NMR
−
titration experiments were performed showing that the
chloroazaphosphatranes can bind anions with association
constants from 20 to 50 M−1, whereas no interaction was
detected with both the protonated counterpart azaphospha-
tranes and the fluoroazaphosphatranes. The substituents on
the equatorial nitrogen atoms probably do not interact directly
with the anion but modulate the electrophilicity of the σ-hole
on the chlorine atom. These results highlight the crucial role of
XB in the recognition of anions by chloroazaphosphatranes
and make them a new class of relevant motifs for X-bonding
with the following features: (i) the XB donor is not a halogen
linked to an aromatic carbon, in contrast with most of the
classical motifs reported today; (ii) the interaction with anion
is comparable to that reached with iodoperfluorobenzene or
iodoimidazolium, although a chlorine atom is involved instead
of a much more polarizable iodine atom; and (iii) the
electronic properties of the R groups on the equatorial
nitrogens can tune the XB properties of the chloroazaphospha-
trane. Experiments are in progress in our laboratory in order to
design anion receptors combining two or more chloroaza-
phosphatrane units or by associating them with other motifs
for a more selective and efficient anion recognition.
Hz), 45.7 (d, J = 7.5 Hz), 28.5 (d, J = 4.5 Hz), 20.3. 31P NMR
(CDCl3, 120 MHz) δ = −13.81. HRMS (ESI): m/z [M ]+ calcd for
C18H39N4PCl+ 377.2595; found: 377.2593.
[ClP(BnNCH2CH2)3N][Cl] (1c-Cl+·Cl−). White solid; yield: 86% (261
mg); mp 145 °C. IR/cm−1: 3364, 3060, 2925, 2884, 1635, 1604,
1493, 1384, 1299, 1261, 1142, 1071, 1024, 971, 920, 865, 766, 696,
590, 510. 1H NMR (CDCl3, 300 MHz) δ = 7.40−7.24 (m, 15H), 4.68
(d, J = 14.7 Hz, 6H), 3.65 (td, J = 6.8, 4.3 Hz, 6H), 3.32 (dt, J = 12.0,
6.7 Hz, 6H). 13C NMR (CDCl3, 75 MHz) δ = 136.9 (d, J = 5.25 Hz),
129.1, 128.2, 127.7, 55.7 (d, J = 4.5 Hz), 44.5 (d, J = 9.75 Hz), 44.2
(d, J = 9.0 Hz). 31P NMR (CDCl3, 120 MHz) δ = −23.44. HRMS
(ESI): m/z [M]+ calcd for C27H33ClN4P+ 479.2126; found: 479.2126.
[ClP(p-OMe-BnNCH2CH2)3N][Cl] (1d-Cl+·Cl−) (Known Com-
pound).81 White solid; yield: 46% (226 mg); mp 205 °C. IR/cm−1:
3744, 3648, 3367, 2946, 2833, 2787, 2362, 1652, 1584, 1541, 1509,
1389, 1419, 1354, 1274, 1172, 1098, 945, 869, 816, 761, 657, 602,
572. 1H NMR (CDCl3, 300 MHz) δ = 7.21 (d, J = 8.7 Hz, 6H), 6.86
(d, J = 8.6 Hz, 6H), 4.59 (d, J = 14.7 Hz, 1H), 3.53 (td, J = 6.8, 4.5
Hz, 6H), 3.23 (dt, J = 13.0 Hz, 6.7 Hz, 6H). 13C NMR (CDCl3, 100
MHz) δ = 159.5, 129.3, 128.8 (d, J = 4.65 Hz), 114.3, 55.4, 54.9 (d, J
= 4.14 Hz), 44.4 (d, J = 9.9 Hz), 43.9 (d, J = 9.59 Hz). 31P NMR
(CDCl3, 120 MHz) δ = −23.38. HRMS (ESI): m/z [M]+ calcd for
C30H39ClN4O3P+ 569.2443; found: 569.2441.
EXPERIMENTAL SECTION
■
General Methods. All reactions were performed under an inert
[ClP(p-CF3-BnNCH2CH2)3N][Cl] (1e-Cl+·Cl−). White solid; yield:
62% (196 mg); mp 155 °C. IR/cm−1: 2327, 2245, 1996, 1781, 1698,
1635, 1622, 1576, 1507, 1473, 1418, 1395, 1157, 1066, 816, 764, 573.
1H NMR (CDCl3, 300 MHz) δ = 7.63 (d, J = 6.0 Hz, 6H), 7.41 (d, J
atmosphere of dry argon. H, 13C, 19F, and 31P NMR spectra were
1
recorded on Bruker AC 300, Bruker AC 400, Bruker 500 HD, and
Bruker Avance III 600 spectrometers. Chemical shifts are reported in
ppm on the δ scale relative to residual CHCl3 (δH = 7.26 ppm, δC =
77.16 ppm) and CH3CN (δH = 1.94 ppm, δC = 1.32 and 118.26 ppm)
as the internal references. High-resolution mass spectra (HRMS) were
performed on a SYNAPT G2 HDMS (Waters) spectrometer
equipped with an atmospheric pressure ionization source (API) that
was pneumatically assisted. Infrared spectra were recorded on a
Bruker TENSOR 27 Fourier Transform infrared spectrometer
equipped with a single reflection diamond Attenuated Total
Reflection accessory (Bruker A222). Anhydrous dichloromethane
was obtained from the Solvent Purification System BRAUN MB-
SPS800. Dry acetonitrile was purchased from chemical suppliers.
Synthesis of Chloroazaphosphatranes. Proazaphosphatranes
(1) were first prepared according to a known procedure.50,58,59,72
Under an atmosphere of argon, in a flame-dried Schlenk flask,
azaphosphatrane 1-H+·Cl− (1.0 equiv) was dissolved in dried CH2Cl2
(C = 0.16 mol·L−1), t-BuOK (2.1 equiv) was added, and the reaction
mixture was stirred at room temperature for 2 h. Then, the solvent
was removed under vacuum, and anhydrous toluene (C = 0.075 mol·
L−1) was added. The reaction mixture was stirred for another 0.5 h,
and then, the suspension was filtered under argon through a two-
necked fritted glass funnel. Then, the solvent was removed under
vacuum to give pure proazaphosphatrane 1. The product was directly
used for the following step.
= 9.0 Hz, 6H), 4.76 (d, J = 15.0 Hz, 6H), 3.91 (q, J = 6.0 Hz, 6H),
3.53 (dt, J = 6.0 Hz, 12.0 Hz, 6H). 13C NMR (CD3CN, 75 MHz) δ =
144.0 (dd, J = 1.5 Hz, 4.5 Hz), 129.6 (d, J = 31.5 Hz), 128.3, 126.4 (q,
J = 3.75 Hz), 125.4 (d, J = 270 Hz), 55.5 (d, J = 5.25 Hz), 46.4 (d, J =
9.0 Hz), 45.5 (d, J = 9.0 Hz). 31P NMR (CDCl3, 120 MHz) δ =
−23.82. 19F NMR (CDCl3, 376 MHz) δ = −62.60. HRMS (ESI): m/
z [M]+ calcd for C30H30N4F9ClP+ 683.1747; found: 683.1747.
Anion Metathesis. In a flame-dried Schlenk flask were added
dried acetonitrile (C = 0.1 mol·L−1) and 1-Cl+·Cl− (1.0 equiv). A
solution of NaPF6 (1.4 equiv) in dried acetonitrile (C = 0.26 mol·L−1)
was added dropwise, and the mixture was stirred for 2 h at room
temperature. The solvent was evaporated under a vacuum, and dried
acetone (C = 0.07 mol·L−1) was added. White solid precipitate was
observed. The supernatant was evaporated under a vacuum to give
−
pure 1-Cl+·PF6
.
[ClP(MeNCH2CH2)3N][PF6] (1a-Cl+·PF6−). Beige solid; yield: 70%
(105 mg); mp 250 °C. IR/cm−1: 2945, 1489, 1394, 1254, 1144, 973,
1
832, 746, 556. H NMR (CD3CN, 300 MHz) δ = 3.37−3.25 (m,
6H), 3.21−3.14 (m, 6H), 2.90 (d, J = 15.0 Hz, 9H). 13C NMR
(CD3CN, 75 MHz) δ = 46.8 (d, JPC = 9.0 Hz), 46.3 (d, JPC = 9.7 Hz),
39.7 (d, JPC = 6.0 Hz). 31P NMR (CD3CN, 120 MHz) δ = −21.34,
−144.61 (sept, JP−F = 697.2 Hz). 19F NMR (CD3CN, 376 MHz) δ =
−71.64, −74.43. HRMS (ESI): m/z [M]+ calcd for C9H21N4ClP+
251.1187; found: 251.1187. X-ray: the product was crystallized from
Et2O/CH3CN. CCDC 2060857 contains the supplementary crystallo-
graphic data for this paper.
To a flame-dried Schlenk tube was added freshly prepared
proazaphosphatrane 1 (1.0 equiv), dried CH2Cl2 (C = 0.33 mol·
L−1), and hexachloroethane (1.02 equiv); the mixture was stirred
under argon at room temperature for 2 h. The solvent was evaporated
under vacuum, and the residual was washed three times by Et2O to
give the desired product 1-Cl+·Cl−.
[ClP(iBuNCH2CH2)3N][PF6] (1b-Cl+·PF6−). White solid; yield: 65%
(169 mg); mp 177 °C. IR/cm−1: 2960, 2928, 2872, 1466, 1390, 1368,
ClP(MeNCH2CH2)3N][Cl] 1a-Cl+·Cl− (Known Compound).80 Beige
solid; yield: 85% (562 mg); mp 65−66 °C. IR/cm−1: 3565, 2960,
1313, 1283, 1176, 1114, 1076, 1058, 833, 780, 595, 556. H NMR
1
(CDCl3, 400 MHz) δ = 3.29 (dt, J = 4.0 Hz, 16.0 Hz, 6H), 3.16 (td, J
= 4.0 Hz, 8.0 Hz, 6H), 3.09 (dd, J = 4.0 Hz, 12.0 Hz, 6H), 2.01 (sept,
J = 8.0 Hz, 3H), 0.94 (d, J = 8.0 Hz, 3H). 13C NMR (CDCl3, 75
1
2727, 2517, 1647, 1465, 1229, 1142, 984, 884, 764, 723, 642. H
NMR (CDCl3, 300 MHz) δ = 3.74 (td, J = 3.0 Hz, 6.0 Hz, 6H), 3.39
(dt, J = 6.0 Hz, 12.0 Hz, 6H), 2.95 (d, J = 15.0 Hz, 9H). 13C NMR
(CDCl3, 75 MHz) δ = 46.4 (d, J = 9.7 Hz), 45.1 (d, J = 9.0 Hz), 39.8
MHz) δ = 58.9 (d, JPC = 1.5 Hz), 47.4 (d, JPC = 9.7 Hz), 45.5 (d, JPC
=
6.7 Hz), 28.6 (d, JPC = 5.2 Hz), 20.2. 31P NMR (CDCl3, 120 MHz) δ
F
Inorg. Chem. XXXX, XXX, XXX−XXX