New bis(diphenylphosphino)aniline derivatives: Synthesis and spectroscopic characterization

Article abstract of DOI:10.1002/hc.20362

Six new multidentate bis(diphenylphosphino)amine [R - N(PPh ₂)₂] ligands have been prepared from the reaction of aniline derivatives, R-NH₂, with Ph₂PCl in the presence of triethylamine. All of the compounds wer

Full text of DOI:10.1002/hc.20362

Heteroatom Chemistry
Volume 18, Number 6, 2007
New Bis(diphenylphosphino)aniline
Derivatives: Synthesis and Spectroscopic
Characterization
Nermin Biricik, Feyyaz Durap, Cezmi Kayan, and Bahattin Gu¨mgu¨m
Department of Chemistry, Science and Art Faculty, University of Dicle, 21280 Diyarbakir, Turkey
Received 21 October 2005; revised 3 July 2006, 15 August 2006
phines have attracted a considerable attention be-
ABSTRACT: Six new multidentate bis(diphenyl-
cause aminophosphines consist of both soft and
phosphino)amine [R N(PPh2)2] ligands have been
hard donor atoms to accommodate metal ions. This
prepared from the reaction of aniline derivatives,
enables the synthesis of compounds containing tran-
R NH2, with Ph2PCl in the presence of triethylamine.
sition metals, which have important applications
All of the compounds were obtained in good yields
in areas such as NMR shift reagents [4], selec-
and were characterized by NMR, IR, and microanal-
tive metal extractions [5], organometallic chemistry,
ꢀ
C
ysis.
2007 Wiley Periodicals, Inc. Heteroatom Chem
and catalysis [6–9]. Recently, new type of catalysts,
ruthenium pyridine–phosphole complex [10] and
chromium diphosphinoamine complexes [11] have
been developed and are used in the transfer hydro-
genation of ketones and the synthesis of 1-hexene,
respectively.
18:613–616, 2007; Published online in Wiley InterScience
(www.interscience.wiley.com). DOI 10.1002/hc.20362
INTRODUCTION
Although anilines are well known and very
cheap commercial reagents, the chemistry of diphos-
phinoamines with P N P skeletons has not been
studied in detail. We report here the synthesis of
some new multidentate aminophosphine ligands de-
rived from aniline derivatives, possessing electron-
donating substituents on an aryl ring. All com-
pounds have been fully characterized by microanal-
Ligands bearing P N P backbone have been known
since 1964 [1]. Several methods have been men-
tioned for the synthesis of aminophosphines and
diphosphinoamines, among them the most com-
mon is aminolysis [2], namely the reaction of phos-
phine chloride with an amine usually provides
the target compound, RNHPRꢁ2 or RN(PR2ꢁ )2, in
high yields. The reaction condition for the synthe-
sis of aminophosphines depends on the nature of
chlorophosphine and the organic precursor. For the
obvious electronic reasons, Ph2PCl is more reactive
toward a nucleophile than chlorodialkylphosphines
[3]. Over the past years, studies of aminophos-
1
ysis: IR, 1H NMR, 13C NMR, and31P–{ H} NMR
spectroscopy.
RESULTS AND DISCUSSION
Six new multidentate bis(diphenylphosphino)ani-
lines were prepared from the commercially avail-
able starting materials, aniline derivatives, using the
aminolysis method in dichloromethane as described
in Scheme 1.
Correspondence to: Nermin Biricik; e-mail: nbiricik@dicle.
edu.tr.
Contract grant sponsor: The Council of Dicle University.
Contract grant number: DUAPK-05-FF-19 project.
c
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2007 Wiley Periodicals, Inc.
613

614 Biricik et al.
SCHEME 1 Aminolysis reactions of anilines with Ph2PCl, Et3N at 0◦C in CH2Cl2.
The synthesis of bis(diphenylphosphino)ani-
lines 1–6 has not been described in the literature so
far. The structure of the compounds was confirmed
by the spectroscopic analysis.
ing electron-donating groups with Ph2PCl in the
presence of Et3N (molar ratio 1:2:2) in CH2Cl2. 31P–
1
{ H} NMR investigation of the reaction mixtures
shows that all the reactions were completed af-
ter 1 h to give the expected products, diphosphi-
The reaction between anilines and Ph2PCl in the
presence of triethylamine is fast, and all the reac-
tion products are soluble in dichloromethane, al-
lowing the reaction to be monitored by 31P NMR
spectroscopy. Recently, the reactions of some aniline
derivatives with Ph2PCl in the presence of triethy-
lamine have been thoroughly studied and different
substances were obtained, depending on the rela-
tive ratio of the reagents, the electron-withdrawing
groups and their positions on the aromatic ring and
solvents such as diethyl ether and dichloromethane.
Aminophosphines (Ph2P NHR) were found as the
main products, and when the reaction conditions
changed diphosphinoamines (R N(PPh2)2) or imin-
odiphosphines (R N PPh2 PPh2) were also formed
as the major products [12].
1
noamines 1–6 (Scheme 1). 31P–{ H} NMR spec-
tra indicate that all compounds display the char-
acteristic signals of bis(diphenylphosphino)amines
between 56 and 69 ppm, and the results are in
agreement with the earlier studies where the chem-
ical shifts of the same functional groups gener-
ally appear between 60 and 70 ppm [13,14]. 31P
NMR chemical shifts (ppm) of the P N P func-
tion of our compounds are changed between 56
and 69 ppm, and the results are consistent with the
mentioned studies. Two singlets at 61.4 and 29.0
were observed for the reaction mixture of 1 in its
1
31P–{ H} NMR spectrum. The main signal at 61.4
was attributed to N-bis(diphenylphosphino)-2,3-
dimethylaniline (1), and the small one was thought
to be that of 2,3-dimethylanilodiphenylphosphine.
When the mixture of 1 was washed with H2O and
As shown in Scheme 1, we investigated the
aminolysis reactions of aniline derivatives possess-
Heteroatom Chemistry DOI 10.1002/hc

Synthesis and Spectroscopic Characteristic of Aniline Derivatives 615
then with Et2O, the minor signal at 29.0 ppm dis-
appeared and only the one signal at 61.4 ppm was
observed. Thus, compound 1 was obtained with
a high yield as a pure product. The results on
the byproduct are in agreement with the chemi-
cal shifts of arylaminodiphenylphosphines, which
gave 31P NMR resonances between 25 and 35 ppm
[15]. There was no evidence for the formation
of iminobiphosphines, producing two sets of dou-
blets at ∼ +10 to ∼ −20 ppm [16], because no
resonances were observed in this region in all
reactions.
ands from the reaction of aniline derivatives bearing
electron-donating groups, such as methyl and ethyl,
and Ph2PCl in a single step, with high yields. Fur-
ther synthesis of their coordination compounds with
transition metals and chalcogenides is in progress.
EXPERIMENTAL
All the starting materials are commercially available
and were used without further purification. Solvents
were dried using the appropriate reagents and were
distilled prior to use. All manipulations were per-
formed under an inert atmosphere of dry nitrogen
using the standard Schlenk techniques. Infra red
spectra were recorded as KBr pellet in the range
4000–400 cm−1 on a Mattson 1000 ATI Unicam FT-IR
spectrometer. 1H and 13C NMR (100.6 MHz) spectra
1
The 31P–{ H} NMR spectra of the reaction ob-
tained from mixture after 1 h of the reaction of 2 and
3 show a single resonance at 61.4 ppm for compound
2 and at 60.2 ppm for compound 3. No byproduct
was observed in these reactions as seen in that of
1. The property of 4 is really very interesting when
compared to compounds 1–3. A comparison of 31P–
1
on Bruker AC 400 spectrometer, and 31P–{ H} NMR
spectra at 162 MHz with δ referenced to external
85% H3PO4. Microanalysis was carried out by using
Fisons EA 1108 CHNS-O instrument, and melting
points were determined with the help of Gallenkamp
MID 350 BM 2.5 apparatus.
1
{ H} NMR spectra of 1–3 and 4 indicates that the
position of the substituted groups is very important.
1
So, the 31P–{ H} NMR spectrum of 4 shows a res-
onance at 56.8 ppm, at lower frequency of about
4 ppm from the other substances. After removal of
the solvent, Et3N·HCI was removed by washing the
residue with water and 4 was isolated in high yields.
Although compounds 1–3 are very stable in air, wa-
ter, and organic solvents, compound 4 is sensitive
to air. It is stable in air for 2 days and completely
General Procedure for Preparation of the
Compounds 1–6
Chlorodiphenylphosphine (3.74 g, 16.5 mmol) was
added slowly to a solution of aniline derivatives
(1.00 g, 8.25 mmol) and Et3N (1.669 g, 16.5 mmol) in
CH2C12 (25 mL) at 0◦C. The resulting white suspen-
sion was stirred for 2 h, and the solvent was removed
under reduced pressure. The solid compounds were
washed with degassed water (3 × 10 mL) and were
dried in air.
1
decomposed after that. Again 31P–{ H} NMR inves-
tigation of decomposed product showed that there
are three different chemical shifts at 35.8–34.5 ppm
as a doublet, 19.9 ppm as a singlet, and −22.5(−23.9)
ppm as a doublet.
1
Notably, 31P–{ H} NMR spectrum of the reac-
tion mixture of 6 shows a singlet at 68 ppm, a shift
of exactly 7 ppm from that of 5, possibly as a con-
sequence of the position of an ethyl group on the
aniline ring. This once again demonstrates that the
steric and electronic effects of substituents on an
aromatic ring for aminophosphines are very impor-
tant. All compounds are colorless and are soluble in
chlorinated solvents, Et2O and THF, but a slow de-
composition can occur in chlorinated solvents [17].
The compounds 1–6 are stable in air and moisture,
except 4.
Bis(diphenylphosphino)-2,3-dimethylaniline
[(Ph2P)2N C6H3 (CH3)2] (1). Yield: 3.50 g, 87%.
1
mp 120–122◦C. H NMR (CDCl3) δ (ppm): 6.51–7.7
(m, 23H, ArH), 2.12 (s, 3H, CH3), 1.53 (s, 3H, CH3).
13C NMR (CDCl3) δ (ppm): (Carm, 146.7; 139.9; 137.7;
136.1; 134.6; 132.5; 129.9; 128.2; 127.7; 125.2), (CCH
,
3
1
20.8; CCH3 , 15.1). 31P–{ H} NMR (CDCl3) δ (ppm):
61.4 (s). IR, ν (cm−1): 3049 (w), 2951 (w), 1570 (w),
1470 (m), 1437 (s), 1377 (w), 1238 (m), 1186 (m),
1094 (s), 914 (s), 882 (s) (P N), 783 (w), 737 (s), 691
(s), 571 (m), 533 (m), 492 (m), 440 (m). C32H29NP2:
calcd C 78.51, H 5.97, N 2.86; found, C 78.66, H
5.75, N 3.01.
The IR spectrum is useful in determination of
νP bonds of aminophosphines and their coordi-
N
nation compounds [18]. We observed that all lig-
ands showed characteristic vibrations about at 900–
700 cm−1 of νP P bonds, which are assigned to νP
Bis(diphenylphosphino)-2,4-dimethylaniline
[(Ph2P)2N C6H3 (CH3)2] (2). Yield: 3.72 g, 92%.
mp 147–149◦C. 1H NMR (CDCl3) δ (ppm): 6.47–7.52
(m, 23H, ArH), 2.25 (s, 3H, CH3), 1.68 (s, 3H,
CH3). 13C−NMR (CDCl3) δ (ppm): (Carm, 144.7;
N
N P
vibrations, producing the evidence for the synthesis
of the compounds.
In conclusion, we have achieved the synthe-
sis of six novel heterodonor tertiary phosphine lig-
Heteroatom Chemistry DOI 10.1002/hc

616 Biricik et al.
Hz), 1.11–1.15 (t, 3H, CH3, 3 JHH = 7.6 Hz). 13C−NMR
(CDCl3) δ (ppm): (Carm, 145.1; 141.1; 140.5; 139.4;
135.3; 133.3; 131.2; 129.0; 128.5; 127.6), (CCH2 , 28.0;
139.9; 136.9; 135.6; 134.7; 132.4; 129.9; 128.4;
1
127.7; 126.8), (CCH , 20.9; CCH3 , 19.4). 31P–{ H} NMR
3
(CDCl3) δ (ppm): 61.4 (s). IR, ν (cm−1): 3054 (w),
2918 (w), 1576 (w), 1491 (m), 1437 (s), 1371 (w),
1213 (m), 1186 (m), 1094 (s), 955 (w), 889 (s) (P N),
811 (w), 743 (s), 696 (s), 589 (w), 558 (m), 498 (m).
C32H29NP2: calcd C 78.51, H 5.97, N 2.86; found C
78.10, H 5.55, N 2.93.
1
CCH3 ,15.6). 31P–{ H} NMR (CDCl3) δ (ppm): 68.5 (s).
IR, ν (cm−1): 3049 (w), 2970 (w), 1550 (m), 1478
(m), 1437 (s), 1306 (w), 1219 (s), 1173 (w), 1100 (m),
1020 (w), 895 (s) (P N), 737 (s), 696 (s), 598 (m),
588 (m), 492 (m). C32H29NP2: calcd C 78.51, H 5.97,
N 2.86; found C 78.56, H 5.68, N 2.78.
Bis(diphenylphosphino)-2,5-dimethylaniline
[(Ph2P)2N C6H3 (CH3)2] (3). Yield: 3.65 g, 91.5%.
mp 164–165◦C. 1H NMR (CDCl3) δ (ppm): 7.16–7.65
(m, 23H, ArH), 2.20 (s, 3H, CH3), 1.76(s, 3H, CH3).
13C−NMR (CDCl3) δ (ppm): (Carm, 146.7; 139.9;
135.5; 134.5; 133.8; 131.2; 130.6; 128.2; 127.8;
REFERENCES
[1] Schmidpeter, A.; Bo¨hm, R.; Groeger, H. Angew
Chem, Int Ed Engl 1964, 3, 704.
[2] (a) Ewart, G.; Lane, A. P.; McKechnie, J.; Payne,
D. S. J Chem Soc A 1964, 1543; (b) Lane, A. P.;
Morton-Blake, D. A.; Payne, D. S. J Chem Soc A 1967,
1492.
[3] Agbassou, F.; Carpentier, J. F.; Hapiot, F.; Suisse, I.;
Mortreux, A. Coord Chem Rev 1998, 1615, 178–180.
[4] Barkaoui, L.; Charrouf, M.; Rager, M. N.; Denise, B.;
Platzer, N.; Rudler, H. Bull Soc Chim Fr 1997, 134,
167.
[5] Navra´til, O.; Herrmann, E.; Sleza´k, P. Collect Czech
Chem Commun 1987, 52, 1708.
[6] (a) King, R. B. Acc Chem Res 1980, 13, 243; (b)
Mague, J. T. J Cluster Sci 1995, 6, 217; (c) Bhat-
tacharyya, P.; Woollins, J. D. Polyhedron 1995, 14,
3367.
[7] Ly, T. Q.; Slawin, A. M. Z.; Woollins, J. D. J Chem
Soc, Dalton Trans 1997, 1611.
[8] Zubiri, I. M. R.; Clarke, M. L.; Foster, D. F.;
Cole-Hamilton, D. J.; Slawin, A. M. Z.; Woollins,
J. D. J Chem Soc, Dalton Trans 2001, 969.
[9] Molloy, K. G.; Petersen, J. L. J Am Chem Soc 1995,
117, 7696.
[10] Thoumazet, C.; Melaimi, M.; Ricard, L.; Mathey, F.;
Le Floch, P. Organometallics 2003, 22(8), 1580.
[11] (a) Carter, A.; Cohen, S. A.; Cooley, N. A.; Murphy,
A.; Scutt, J.; Wass, D. F. Chem Commun 2002, 8, 858;
(b) Bowen, L. E.; Wass, D. F. Organometallics 2006,
25(3), 555; (c) Blann, K.; Bollmann, A.; Dixon, J. T.;
Hess, F. M.; Killian, E.; Maumela, H.; Morgan, D. H.;
Neveling, A.; Otto, S.; Overett, M. J. Chem Commun
2005, 5, 620; (d) Overett, M. J.; Blann, K.; Bollmann,
A.; Dixon, J. T.; Hess, F.; Killian, E.; Maumela, H.;
Morgan, D. H.; Neveling, A.; Otto, S. Chem Commun
2005, 5, 622.
[12] Fei, Z.; Scopelliti, R.; Dyson, P. J. J Chem Soc, Dalton
Trans 2003, 2772.
[13] Gaw, K. G.; Smith, M. B.; Steed, J. W. J Organomet
Chem 2002, 664, 294.
[14] Fei, Z.; Dyson, P. J. Coord Chem Rev 2005, 249, 2056.
[15] Fei, Z.; Scopelliti, R.; Dyson, P. J. J Chem Soc, Dalton
Trans 2003, 2772.
[16] Fei, Z.; Biricik, N.; Scopelliti, R.; Dongbin, Z.; Dyson,
P. J. Inorg Chem 2004, 43(7), 2228.
1
126.7), (CCH , 20.8; CCH3 , 19.1) 31P–{ H} NMR
3
(CDCl3) δ (ppm): 60.2 (s). IR, ν (cm−1): 3076 (w),
2970 (w), 1589 (w), 1483 (m), 1437 (s), 1312 (w),
1233 (m), 1179 (m), 1113 (m), 1086 (m), 993 (m),
909 (s) (P N), 855 (s), 803 (m), 737 (s), 691 (s), 590
(m), 525 (m), 473 (m). C32H29NP2: calcd C 78.51, H
5.97, N 2.86; found C 78.20, H 5.78, N 2.96.
Bis(diphenylphosphino)-2,6-dimethylaniline
[(Ph2P)2N C6H3 (CH3)2] (4). Yield: 3.8 g, 88%. mp
1
100–101◦C. H NMR (CDCl3) δ (ppm): 6.9–7.82 (m,
23H, ArH), 1.607 (s, 6H, CH3). 13C−NMR (CDCl3) δ
(ppm): (Carm, 145.7; 139.6; 138.5; 135.2; 134.3; 134.2;
1
129.3; 128.9; 127.9; 126.2), (CCH3 , 20.5). 31P–{ H}
NMR (CDCl3) δ (ppm): 56.8 (s). IR, ν (cm−1): 3057
(w), 2932 (w), 1595 (w), 1478 (m), 1437 (s), 1325
(w), 1179 (s), 1094 (m), 1034 (w), 878 (s) (P N),
770 (w), 750 (s), 696 (s), 544 (m), 492 (m), 452 (m).
C32H29NP2: calcd C 78.51, H 5.97, N 2.86; found C
78.9, H 6.02, N 2.78.
Bis(diphenylphosphino)-2-ethylaniline
[(Ph2P)2N C6H4 (C2H5)] (5). Yield: 3.26, 81%.
mp 104–107◦C. 1H NMR (CDCl3) δ (ppm): 6.65–7.66
3
(m, 24H, ArH), 2.62–2.56 (q, 2H, CH2, JHH = 7.4
Hz), 1.27–1.24 (t, 3H, CH3, 3 JHH = 7.4 Hz). 13C−NMR
(CDCl3) δ (ppm): (Carm, 146.7; 142.6; 135.0; 132.4;
131.2; 130.4; 130.0; 128.5; 126.3; 125.8), (CCH2 , 23.9;
1
CCH ,13.7).31P–{ H} NMR (CDCl3) δ (ppm): 61.6 (s).
IR, 3ν (cm−1): 3049 (w), 2964 (w), 1589 (w), 1483 (m),
1437 (s), 1317 (w), 1226 (m), 1179 (m), 1100 (m),
1028 (w), 947 (m), 895 (s) (P N), 855 (s), 803 (m),
743 (s), 696 (s), 544 (m), 486 (m). C32H29NP2: calcd
C 78.51, H 5.97, N 2.86; found C 78.15, H 5.77, N
2.95.
[17] Lindner, E.; Mohr, M.; Nachtigal, C.; Fawzi, R.;
Henkel, G. J. Organomet Chem 2000, 595, 166.
[18] Necas, M.; Foreman, St. M. R.; Marek, J.; Slawin, A.
M. Z.; Woollins, J. D.; Novosad, J. New J Chem 2001,
25, 1256.
Bis(diphenylphosphino)-4-ethylaniline
[(Ph2P)2N C6H4 (C2H5)] (6). Yield: 3.42 g, 85%.
mp 104–107◦C. 1H NMR (CDCl3) δ (ppm): 6.55–7.38
3
(m, 24H, ArH), 2.47–2.53 (q, 2H, CH2, JHH = 7.5
Heteroatom Chemistry DOI 10.1002/hc