Insertion of carbon fragments into P(III)-N bonds in aminophosphines and aminobis(phosphines): Synthesis, reactivity, and coordination chemistry of resulting phosphine oxide derivatives

Article abstract of DOI:10.1021/ic026118t

Reactions of N-aryl and N-alicyclic derivatives of aminophosphines with paraformaldehyde lead to methylene insertion into P-N bond followed by oxidation of phosphorus from the P(III) to P(V) state. When N-alkyl derivatives are reacted with paraformaldehyd

Full text of DOI:10.1021/ic026118t

Inorg. Chem. 2003, 42, 1272−1281
Insertion of Carbon Fragments into P(III)−N Bonds in Aminophosphines
and Aminobis(phosphines): Synthesis, Reactivity, and Coordination
Chemistry of Resulting Phosphine Oxide Derivatives. Crystal and
Molecular Structures of (Ph2P(O)CH ) NR (R ) Me, nPr, nBu),
2 2
Ph2P(O)CH(OH)nPr, and cis-[MoO Cl2{(Ph2P(O)CH ) NEt-KO,KO}]
2
2 2
,†
Srinivasan Priya,† Maravanji S. Balakrishna,* Joel T. Mague,‡ and Shaikh M. Mobin§
Department of Chemistry, Indian Institute of Technology, Bombay, Mumbai 400 076, India,
Department of Chemistry, Tulane UniVersity, New Orleans, Louisiana 70118,
and National Single-Crystal X-ray Diffraction Facility, Indian Institute of Technology,
Bombay, Mumbai 400 076, India
Received October 18, 2002
Reactions of N-aryl and N-alicyclic derivatives of aminophosphines with paraformaldehyde lead to methylene insertion
into P−N bond followed by oxidation of phosphorus from the P(III) to P(V) state. When N-alkyl derivatives are
reacted with paraformaldehyde, dimerization takes place to afford bis(phosphine oxide)s of the type Ph2P(O)CH N-
2
n
n
(R)CH P(O)Ph2 (R ) Me, Pr, Bu). Aminobis(phosphines) also undergo methylene insertion when treated with
2
paraformaldehyde to give bis(phosphine oxides) Ph2P(O)CH N(R)CH P(O)Ph2 (R ) Me, Et, nPr, iPr, nBu) in good
2
2
yield. The reaction of aminophosphines with aromatic aldehydes ArCHO leads to insertion of “ArCH” into the P−N
bond to give Ph2P(O)CH(R)N(H)Ph (R ) C H , furfuryl, o-C H OH), but with aliphatic aldehydes such as butanal,
6
5
6 4
P−N bond cleavage takes place to afford R-hydroxy phosphine oxide. The reaction of aminobis(phosphines) with
both aromatic and aliphatic aldehydes leads to the formation of R-hydroxy phosphine oxides through P−N bond
cleavage whereas the reaction with furfural leads to the P−N bond insertion. The structure of the R-hydroxy derivative
Ph2P(O)CR(H)(OH)nPr shows intermolecular hydrogen bonding between OH and PdO oxygen. The phosphine
oxide derivatives act as bidentate ligands and form chelate complexes with Co(II), Mo(VI), Th(IV), and U(VI) derivatives.
The crystal structure of the molybdenum complex, cis-[MoO Cl2{(OPPh2CH ) NEt-κO,κO}], shows the distorted
2
2 2
octahedral geometry around Mo with two oxo groups cis to each other.
Introduction
cleavage can also occur in the reactions of R2PCl with amines
in the presence of trace amounts of moisture wherein the
initially formed P-N bond(s) cleave(s) to give the diphos-
phine monoxide as described in Scheme 2. King4 and others5
Although the coordination chemistry of aminobis(phos-
phines) with the P-N-P framework is very extensive,1
studies focused on the reactivity of P(III)-N bonds is
limited.2 This may be due to the sensitivity of P(III)-N bonds
toward acid or base-catalyzed hydrolysis which results in
the cleavage of P(III)-N bonds to give P(V) oxide with the
liberation of secondary amines as shown in Scheme 1. This
type of cleavage is illustrated in the reactions of aminobis-
(phosphines) with phosphoryl azides.3 Similar P-N bond
(1) (a) Knorr, M.; Storhmann, C. Organometallics 1999, 18, 248. (b)
Ellermann, J.; Gabold, P.; Knoch, F. A.; Moll, M.; Pohl, D.; Sutter,
J.; Bauer, W. J. Organomet. Chem. 1996, 525, 89. (c) Ellermann, J.;
Schelle, C.; Knoch, F. A.; Moll, M.; Pohl, D. Monatsh. Chem. 1996,
127, 783. (d) Ellermann, J.; Utz, J.; Knoch, F. A.; Moll, M. Z. Anorg.
Allg. Chem. 1996, 622, 1871. (e) Ellermann, J.; Sutter, J.; Schelle,
C.; Knoch, F. A.; Moll, M. Z. Anorg. Allg. Chem. 1993, 619, 2006.
(f) Arnold, D. I.; Cotton, F. A.; Kuehn, F. E. Inorg. Chem. 1996, 35,
4733, 5764. (e) Ellermann, J.; Schelle, C.; Moll, M.; Knoch, F. A.;
Bauer, W. Z. Anorg. Allg. Chem. 1995, 621, 789. (f) Babu, R. P. K.;
Krishnamurthy, S. S.; Nethaji, M. Organometallics 1995, 14, 2047.
(2) (a) Hudson, R. F.; Mancuso, A. Phosphorus 1972, 1, 271. (b) William,
A. H.; Harry, H. S. Inorg. Chem. 1964, 3, 617. (c) Brudjebel, H.;
Goncalves, H.; Mathis, F. Bull. Chim. Soc. Fr. 1974, 7.
* To whom correspondence should be addressed. E-mail: krishna@
iitb.ac.in. Fax: (+91) 22 576 7152, 572 3480.
† Department of Chemistry, Indian Institute of Technology.
‡ Department of Chemistry, Tulane University.
§ National Single-Crystal X-ray Diffraction Facility, Indian Institute of
Technology.
(3) Balakrishna, M. S.; Santarsiero, B. D.; Cavell, R. G. Inorg. Chem.
1994, 33, 3079.
1272 Inorganic Chemistry, Vol. 42, No. 4, 2003
10.1021/ic026118t CCC: $25.00 © 2003 American Chemical Society
Published on Web 01/23/2003

Insertion of Carbon Fragments into P(III)-N Bonds
As a part of our interest9,14 and the others,15 we have
investigated the reactions of aminophosphines and aminobis-
(phosphines) with aldehydes in detail and herein we report
the synthesis and X-ray structure of several phosphine oxide
derivatives and their interactions with transition metals and
lanthanides. The X-ray structure of a molybdenum complex
is also described.
Scheme 1
Results and Discussion
Scheme 2
The stability of P(III)-N bonds in cyclic and acyclic
phosphazanes depends to a large extent on the substituents
on phosphorus and nitrogen.16 The P(III)-N bonds are
nominally single but show partial double bond character due
to Npπ-Pdπ donor bonding. The P-N bonds can survive a
variety of nucleophilic substitution reactions at phosphorus
centers in both cyclic and acyclic phosph(V)azenes and
phosph(III)azane systems.16 However they are susceptible
to acid/base-catalyzed hydrolysis reactions in the presence
of one or more P-Cl bonds. In the absence of P-Cl bonds,
P-N bonds are even stable to lithium reagents. The present
investigation is aimed at further understanding of stability
and reactivity of P-N bonds in aminophosphines.
have also reported such P-N bond cleavage in metal
complexes of aminobis(phosphines) in the presence of trace
amounts of acid. In contrast, reports on the insertion of
molecular fragments into P(III)-N bonds are rare. Hudson6
and co-workers have reported the insertion of phenyl
isocyanate into the P-N bond of (EtO)2PN(H)R which led
to the isolation of isomeric (EtO)2PNRCON(H)Ph and
(EtO)2PNPhCON(H)R involving a quaternized phosphorus
intermediate.6 Similarly the reaction of P(NR2)3 with CO2
inserts carbon dioxide into the P-N bonds to afford mono-,
(R2N)2POOCNR2, and dicarbamates, (R2N)P(OOCNR2)2.7
Interestingly, such insertion into OdP(NR2)3 was unsuc-
cessful. However, Cavell and co-workers8 have reported the
insertion of CO2, COS, or CS2 into the P(V)-N bond of
(CH3)(CF3)2PN(CH3)2, which yielded hexacoordinated phos-
phorus compounds. Recently we have described the first
example of methylene insertion into the P(III)-N bond in
the reaction of N-phenylaminodiphenylphosphine, PhN(H)-
PPh2, with paraformaldehyde.9 The interest for this investiga-
tion stems from the fact that such insertion reactions could
lead to the isolation of phosphine oxide derivatives with a
variety of substrates that can be used as source of organic
fragments in synthesis. Further, such reactions generate a
variety of phosphine oxide derivatives which can be potential
herbicidal, antimicrobial, and neuroactive reagents.10 Also,
they can be used in some organic transformations such as
formation of R-substituted phosphonates11 and alkenes12 and
in the extraction of rare earths from radioactive wastes.13
i
n
Aminophosphines Ph2PN(H)R (R ) Ph, Me, Et, Pr, Pr,
nBu) were prepared as described previously.27 The cyclo-
(11) Kumar, K. P.; Muthaiah, C.; Kumaraswamy, S.; Kumaraswamy, K.
C. Tetrahedron Lett. 2001, 42, 3219.
(12) (a) Clayden, J.; Collington, E. W.; Lamont, R. B.; Warren, S.
Tetrahedron Lett. 1993, 34, 2203. (b) Armstrong, D. R.; Barr, D.;
Davidson, M. G.; Hutton, G.; O’Brien, P.; Snaith, R.; Warren, S. J.
Organomet. Chem. 1997, 529, 29.
(13) (a) Archelas, E.; Buono, G.; Waegell, B. Polyhedron 1982, 1, 683.
(b) Burger, L. L. Nucl. Sci. Eng. 1963, 16, 428. (c) Chmutova, M. K.;
Kochetokova, N. E.; Myasoedev, B. F. J. Inorg. Nucl. Chem. 1978,
40, 1423.
(14) (a) Balakrishna, M. S.; Ramaswamy K.; Abhyankar, R. M. J.
Organomet. Chem. 1998, 560, 131. (b) Balakrishna, M. S.; Abhyankar,
R. M.; Mague, J. T. J. Chem. Soc., Dalton Trans. 1999, 1407. (c)
Balakrishna, M. S.; Panda, R.; Smith, D. C., Jr.; Klaman, A.; Nolan,
S. P. J. Organomet. Chem. 2000, 599, 156. (d) Balakrishna, M. S.;
Panda, R.; Mague, J. T. Inorg. Chem. 2001, 40, 5620. (e) Balakrishna,
M. S.; Teipel, S.; Pinkerton, A. A.; Cavell, R. G. Inorg. Chem. 2001,
42, 2733. (f) Balakrishna, M. S.; Abhyankar, R. A.; Walwalker, M.
G. Tetrahedron Lett. 2001, 42, 2733. (g) Balakrishna, M. S.;
Walwalker, M. G. J. Organomet. Chem. 2001, 628, 76.
(15) (a) Tyka, R.; Hagele, G.; Peters, J. Phosphorus Sulfur 1987, 34, 31.
(b) Claydon, J.; Warren, S. Angew Chem., Int. Ed. Engl. 1996, 35,
241 and references therein. (c) Muthiah, C.; Kumar, K. P.; Kuma-
raswamy, S.; Kumaraswamy, K. C. Tetrahedron 1998, 54, 14315.
(16) Balakrishna, M. S.; Reddy, V. S.; Krishnamurthy, S. S.; Nixon, J. F.;
Burckett St. Laurent, J. C. T. R. Coord. Chem. ReV. 1994, 129, 1.
(17) Ewart, G.; Lane, A. P.; McKechnie, J.; Payne, D. S. J. Chem. Soc.
1964, 1543.
(18) Panattoni, C.; Bandoli, G.; Bortolozzo, G.; Clemente, D. A.; Croatto,
U. J. Chem. Soc. A 1970, 2778.
(19) Rankin, D. W. H.; Robertson, H. E.; Seip, R.; Schmidbaur, H.;
Blaschke, G.; J. Chem. Soc., Dalton Trans. 1985, 827.
(20) Takaya, H.; Mashima, K.; Koyano, K.; Yagi, M.; Kumobayashi, H.;
Taketomi, T.; Akutagawa, S.; Noyori, R. J. Org. Chem. 1986, 51,
629.
(21) Cameron, T. S.; Dahlen, B. J. Chem. Soc., Perkin Trans. 2 1975, 1737.
(22) Butcher, R. J.; Penfold, B. R.; Sinn, E. J. chem. Soc., Dalton Trans.
1979, 668.
(4) Newton, M. G.; King, R. B.; Chang, M.; Gimeno, J. J. Am. Chem.
Soc. 1978, 100, 1632.
(5) Balakrishna, M. S.; Krishnamurthy, S. S. Indian J. Chem. 1991, 30A,
536.
(6) (a) Hudson, R. F.; Searle, R. J. G., Chem. Commun. 1967, 1249. (b)
Brown, C.; Hudson, R. F.; Searle, R. J. G. Phosphorus 1973, 2, 287.
(7) Aresta, M.; Quaranta, E. J. Org. Chem. 1988, 53, 4154.
(8) Cavell, R. G.; The, K. I.; van de Griend, L. Inorg. Chem. 1981, 20,
3813.
(9) Priya, S.; Balakrishna, M. S.; Mague, J. T. Inorg. Chem. Commun.
2001, 4, 437.
(23) Florian, L. R.; Corey, E. R. Inorg. Chem. 1968, 7, 722.
(24) Wells, A. F. Structural Inorganic Chemistry, 3rd ed.; Clarendon
Press: London, 1962; p 337.
(25) Pauling, L. The Nature of the Chemical Bond, 3rd ed.; Cornell
University Press: Ithaca, NY, 1960; p 260.
(26) Armarego, W. L. F.; Perrin, D. D. Purification of Laboratory
Chemicals, 4th ed.; Butterworth-Heinemann Linacre House: Jordan
Hill, Oxford, U.K., 1996.
(10) Kafarski, P.; Mastalerz, P. Aminophosphonates. Beitr. Wirkstofforsch.
1984, 21, 1.
(27) Wiegrabe, W.; Bock, H. Chem. Ber. 1968, 101, 1414.
Inorganic Chemistry, Vol. 42, No. 4, 2003 1273

Priya et al.
Scheme 3
hexylamine derivative, Ph2PN(H)C6H11 (1), was prepared in
80% yield by reacting chlorodiphenylphosphine with 2 equiv
of cyclohexylamine in n-hexane.
Recently, we have described9 the reaction of Ph2PN(H)-
Ph with paraformaldehyde to give phosphine oxide Ph2P-
(O)CH2N(H)Ph. The product is a consequence of methylene
insertion into a P-N bond followed by the oxidation of the
P(III) center to P(V). The cyclohexylamine derivative 1 reacts
in a fashion similar to afford Ph2P(O)CH2N(H)C6H11 (3) in
70% yield. The IR spectrum of 3 shows νNH at 3243 cm-1;
the low-frequency shift of 60 cm-1 when compared to the
parent compound is attributed to the intermolecular hydrogen
bonding (N-H‚‚‚OdP) as reported earlier.9 The 31P NMR
spectrum of 3 shows a single resonance at 30.6 ppm as
expected. Interestingly, the reactivity of n-alkylaminophos-
n
n
phines, Ph2PN(H)R (R ) Et, Pr, Bu), with paraformalde-
hyde differs significantly and gives exclusively the bis-
(phosphine oxide) derivatives of the type Ph2P(O)CH2N(R)-
CH2P(O)Ph2 in 60-70% yield. The formation of products,
Ph2P(O)CH2N(R)CH2P(O)Ph2 (R ) Et (5), nPr (6), nBu (8)),
from the alkylaminophosphines may be due to the prior
condensation of two alkylaminophosphines into the corre-
sponding aminobis(phosphines) with the elimination of a
molecule of alkylamine, which then reacts with paraform-
aldehyde to give the product as shown in Scheme 3. At
high temperature, the condensation of n-alkylaminophos-
phines into the corresponding aminobis(phosphines) with
elimination of alkylamine is reported.17 The absence of νNH
in the IR spectra of compounds 5, 6, and 8 confirms the
dimerization of alkylaminophosphines and also the methylene
insertion into the P-N bonds. The reaction of aminobis-
(phosphines) Ph2PN(R)PPh2 (R ) Me, Et, nPr, iPr, nBu) with
2 equiv of paraformaldehyde facilitated methylene insertion
into both the P-N bonds to give Ph2P(O)CH2N(R)CH2P-
(O)Ph2 (R ) Me (4), Et (5), nPr (6), iPr (7), nBu (8)) in good
yields. The 31P NMR spectra of the compounds 4-8 show
a single resonance in the range of 29-31 ppm. The 1H NMR
spectra of 4-8 show doublets in the range of 3-4 ppm for
Figure 1. Perspective view of the compounds 4, 6, and 8 with atomic
numbering scheme. Thermal ellipsoids are drawn with 50% probability level,
and hydrogen atoms are omitted for clarity.
methylene protons with a 2JPH coupling of 5-6 Hz. Further
confirmation of the structures of compounds 4, 6, and 8
comes from single-crystal X-ray diffraction studies.
The structures of Ph2P(O)CH2N(R)CH2P(O)Ph2 (R ) Me
n
n
(4), Pr (6), Bu (8)) with atom numbering schemes are
shown in Figure 1. The crystal data and selected bond lengths
and bond angles for 4, 6, and 8 are given in the Tables 1-3,
respectively. All the three structures show a distorted
tetrahedral geometry about the phosphorus centers and
pyramidal environment around the nitrogen center with the
sum of the angles in the range 332-335°. The two PdO
bonds are mutually anti to each other in all three compounds.
The PdO bond distances in 4 (1.486(11), 1.471(12) Å), 6
(1.483(4), 1.488(5) Å), and 8 (1.487(1), 1.481(1) Å) are
longer than that in Ph3PO (1.46 Å),18 while they are shorter
t
when compared with Bu3PO (1.590 Å)19 and BINAPO
1274 Inorganic Chemistry, Vol. 42, No. 4, 2003

Insertion of Carbon Fragments into P(III)-N Bonds
Table 1. Crystallographic Data for 4, 6, 8, and 26
4
6
8
14
26
empirical formula
fw
C27H27NO2P2
459.44
C29H31NO2P2
487.49
C30H33NO2P2
501.51
C16H19O2P
274.28
C28H29Cl2MoNO4P2‚0.3CH2Cl2
697.84
cryst system
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
orthorhombic
Pna21 (No. 33)
10.354(1)
28.375(5)
8.275(2)
orthorhombic
P21cn (No. 1)
8.468(8)
15.126(1)
20.262(2)
triclinic
P-1 (No. 2)
8.053(2)
10.287(2)
16.264(3)
85.72(3)
89.53(3)
89.81(3)
1343.5(5)
2
1.240
0.2
293
0.0395
0.1122
0.0439, 0.753
monoclinic
P21/n (No. 14)
10.595(1)
10.422(1)
13.952(2)
orthorhombic
Pbca (No. 61)
16.822(8)
16.191(11)
23.722(13)
94.333(8)
2431.2(7)
4
1.255
0.2
293
0.085
0.1349
0.0227, 0.000
2595.2(4)
4
1.248
0.194
293
1536.2(3)
4
1.186
0.2
293
0.0441
0.1100
6461.0(6)
1
1.435
0.8
Z
D
calcd (g cm-1
)
µ(Mo KR)a (mm-1
)
temp (K)
293
Rb
0.0521
0.1045
0.069
0.238
0.1431, 0.000
c
Rw
weight for a, b
a Graphite monochromated. b R ) ∑|Fo - Fc|/∑|Fo|. c Rw ) [∑w(Fo - Fc )/∑w(Fo )2]1/2; w ) 1/[σ2(Fo ) + (aP)2 + bP]. P ) 1/3[Fo + 2Fc ].
2
2
2
2
2
2
Scheme 4
Table 2. Selected Bond Distances (Å) for 4, 6, and 8
bond dists
4
6
8
P(1)-O(1)
P(1)-C(1)
P(1)-C(7)
P(1)-C(13)
P(2)-O(2)
P(2)-C(14)
P(2)-C(15)
P(2)-C(21)
N-C(13)
1.486(11)
1.827(15)
1.815(17)
1.808(15)
1.471(12)
1.819(14)
1.829(18)
1.806(17)
1.464(18)
1.452(18)
1.467(19)
1.483(4)
1.821(7)
1.808(6)
1.821(7)
1.488(5)
1.807(7)
1.806(7)
1.818(6)
1.460(8)
1.468(8)
1.487(8)
1.487(2)
1.816(2)
1.805(2)
1.820(2)
1.481(2)
1.823(2)
1.805(2)
1.816(2)
1.464(3)
1.464(3)
1.482(3)
N-C(14)
N-C(27)
Table 3. Selected Bond Angles (deg) for 4, 6, and 8
bond angles
4
6
8
O(1)-P(1)-C(1)
O(1)-P(1)-C(7)
O(1)-P(1)-C(13)
C(1)-P(1)-C(7)
C(1)-P(1)-C(13)
C(7)-P(1)-C(13)
O(2)-P(2)-C(14)
O(2)-P(2)-C(15)
O(2)-P(2)-C(21)
C(14)-P(2)-C(15)
C(14)-P(2)-C(21)
C(15)-P(2)-C(21)
C(13)-N-C(14)
C(13)-N-C(27)
C(14)-N-C(27)
110.6(7)
110.3(7)
117.5(7)
109.0(7)
107.2(7)
101.6(7)
114.5(6)
111.6(9)
113.6(7)
107.6(7)
102.3(7)
106.6(9)
110.9(11)
111.7(11)
111.7(11)
112.0(3)
110.8(3)
115.8(3)
107.5(3)
107.3(3)
102.6(3)
114.6(3)
112.6(3)
111.6(3)
100.9(3)
109.2(3)
107.2(3)
111.1(5)
112.4(5)
111.4(5)
112.9(1)
112.6(1)
114.1(1)
106.4(1)
102.3(1)
107.8(1)
115.1(1)
112.3(1)
110.9(1)
105.7(1)
103.8(1)
108.3(1)
110.5(2)
110.5(2)
111.8(1)
N,N′-Bis(diphenylphosphino)piperazine reacts with 2 equiv
of paraformaldehyde to give the methylene-inserted product,
Ph2P(O)CH2N(C2H4)2NCH2P(O)Ph2 (9), in good yield. The
31P NMR spectrum of the product 9 shows a single resonance
1
at 27.3 ppm, while the H NMR spectrum shows a doublet
2
at 4.23 ppm with JPH coupling of 5.2 Hz for methylene
protons. When bis(diphenylphosphino)ethylenediamine was
treated with paraformaldehyde in 1:2 molar ratio, apart from
the two methylene groups inserted into two P-N bonds,
another methylene bridge was established between the two
nitrogen centers. This may result from nucleophilic addition
at N to give NCH2OH, which further condenses with NH of
the substrate to give the product 10 as shown in Scheme 4.
The 31P NMR spectrum of 10 shows a single resonance at
28.3 ppm. The methylene groups inserted between P-N
(1.506 Å).20 The P-C bond distances are comparable with
literature values.21 The N-C bond distances are in the range
of 1.452-1.482 Å, slightly longer when compared to the
same in Ph2P(O)CH2N(H)Ph (1.441(2) and 1.375(2) Å).9
1
bonds appear as doublets at 3.44 ppm in its H NMR
The reaction of Ph2PN(H)PPh2 with paraformaldehyde
afforded Ph2P(O)CH2OH. The formation of Ph2P(O)CH2OH
could be due to the initial cleavage of the P-N bond to form
Ph2POH and then Ph2P(O)H, which reacts with paraform-
aldehyde to give Ph2P(O)CH2OH. In contrast, Ph2PN(Ph)-
PPh2 did not react with paraformaldehyde even under
vigorous conditions and the unreacted starting materials are
recovered. The controlled methylene insertion into one of
the P-N bonds to make mixed-valent phosphine derivatives
of the type Ph2P(O)CH2N(R)PPh2 have been unsuccessful.
spectrum with 2JPH coupling of 7.19 Hz, whereas the bridging
methylene group appears as a singlet at 3.59 ppm.
When aromatic aldehydes are treated with aminophos-
phines, a “CH(R)” group is inserted into the P-N bond
followed by oxidation of phosphorus from P(III) to P(V).
The reaction of RCHO (R ) Ph, OC4H3, C6H4OH-o) with
Ph2PN(H)Ph afforded Ph2P(O)CH(R)N(H)Ph (R ) Ph (11),
OC4H3 (12), C6H4OH-o (13)) in 65-89% yields as shown
in Scheme 5. The IR spectra of 11-13 show νNH around
3300-3390 cm-1. The 31P NMR spectra of 11-13 show
Inorganic Chemistry, Vol. 42, No. 4, 2003 1275

Priya et al.
Scheme 5
single resonances in the range of 30-37 ppm while their 1H
NMR spectra show doublets around 5.3-5.5 ppm with 2JPH
couplings in the range of 7-12 Hz for CH protons.
The reaction of butyraldehyde with Ph2PN(H)Ph afforded
Ph2P(O)CH(OH)nPr (14) in 89% yield as shown in Scheme
5. In this reaction, the P-N bond cleavage takes place instead
of P-N bond insertion. The IR spectrum of 14 shows a band
at 3207 cm-1 corresponding to an OH group. The 31P NMR
spectrum of 14 exhibits a single resonance at 31.3 ppm
whereas the 1H NMR spectrum shows a doublet for the CH
Figure 2. (a) Perspective view of the compound 14 with atomic numbering
scheme. Thermal ellipsoids are drawn with 50% probability level, and
hydrogen atoms are omitted for clarity. (b) Intermolecular H-bonding
interaction between O-H‚‚‚OdP of another molecule.
2
proton at 4.41 ppm with a JPH coupling of 10.3 Hz.
Table 4. Selected Bond Distances (Å) and Bond Angles (deg) for 14
n
n
The reaction of PrN(PPh2)2 with RCHO (R ) Pr, Ph,
C6H4OH-o) yielded R-hydroxy phosphine oxides Ph2P(O)CH-
(OH)R (R ) nPr (14), Ph (15), C6H4OH-o (16)) in 40-45%
yields. The formation of these products may be due to the
prior cleavage of the P-N bond to form Ph2P(O)H, which
then reacts with aldehyde to give Ph2P(O)CH(OH)R. Com-
pounds 14-16 show νOH around 3200-3250 cm-1 in their
IR spectra. The 31P NMR spectra of 14-16 show a single
Bond Distances
P(1)-O(1)
P(1)-C(1)
P(1)-C(7)
1.486(2)
1.802(3)
1.811(3)
P(1)-C(13)
O(2)-C(13)
1.829(3)
1.419(4)
Bond Angles
O(1)-P(1)-C(1)
O(1)-P(1)-C(7)
O(1)-P(1)-C(13)
C(1)-P(1)-C(7)
C(1)-P(1)-C(13)
111.3(1)
110.7(1)
114.0(1)
107.9(1)
106.2(1)
C(7)-P(1)-C(13)
P(1)-C(13)-O(2)
P(1)-C(13)-C(14)
O(2)-C(13)-C(14)
106.5(1)
108.5(2)
111.5(2)
113.7(3)
1
resonance in the range of 30-37 ppm, and the H NMR
spectra show doublets around 4.4-5.5 ppm for the CH proton
with 2JPH couplings in the range 5-10 Hz. The structure of
14 is confirmed by a single-crystal X-ray diffraction study.
The crystal data, bond distances, and bond angles for 14 are
listed in Tables 1 and 4, and a perspective view of the
molecule is shown in Figure 2. The structure of 14 shows
distorted tetrahedral geometry around the phosphorus center.
The PdO bond length is 1.486(2) Å, and the P-C bond
distances are in the range 1.802(3)-1.829(3) Å. Compound
14 exists as a dimer in the crystal due to intermolecular
O-H‚‚‚OdP hydrogen bonding between H (from OH) of
one molecule and O (from PdO) of an adjacent molecule
(d(O‚‚‚O) ) 2.682(3) Å, d(H(111)-O) ) 1.91(3) Å; the
O-H‚‚‚O bond angle is 167(4)°). The anti conformation of
the OH group and PdO oxygen of the adjacent molecule
facilitates this type of strong intermolecular hydrogen bond-
furfural, it afforded (Ph2P(O)CH(OC4H3))2NnPr (17) in 37%
yield. The IR spectrum of 17 shows νPO at 1187 cm-1. The
31P NMR spectrum of the compound 17 shows a single
resonance at 29.8 ppm, and the 1H NMR spectrum shows a
doublet at 5.53 ppm for the CH proton with a 2JPH coupling
of 5.99 Hz.
Coordination Chemistry of the Phosphine Oxides. The
phosphine oxides readily react with oxophilic metals to give
coordination complexes. When the compound Ph2P(O)CH2-
NHPh (2) is treated with group 12 metal precursors MX2
(M ) Zn, Cd; X ) acetate and M ) Hg; X ) iodide),
tetrahedral complexes [(Ph2P(O)CH2NHPh)MX2] (M ) Zn
-
(18), Cd (19); X ) COOCH3 and M ) Hg (20); X ) I-)
were obtained in good yield. The IR spectra of the complexes
18-20 show shifts for both νNH and νPO as compared to the
free ligand 2 indicating the interaction of nitrogen and oxygen
with the metal centers. The 1H NMR spectra of the
complexes 18-20 show broad singlets for the NH protons
n
ing. The reaction of PrN(PPh2)2 with furfural is different
from other aldehydes, but it is similar to that with paraform-
n
aldehyde. When PrN(PPh2)2 is treated with 2 equiv of
1276 Inorganic Chemistry, Vol. 42, No. 4, 2003

Insertion of Carbon Fragments into P(III)-N Bonds
Scheme 6
Figure 3. Perspective view of the complex 26 with atomic numbering
scheme. Thermal ellipsoids are drawn with 50% probability level, and
hydrogen atoms are omitted for clarity.
Table 5. Selected Bond Distances (Å) and Bond Angles (deg) for 26
Bond Distances
Mo-O(1)
Mo-O(2)
Mo-O(3)
Mo-O(4)
Mo-Cl(1)
Mo-Cl(2)
P(1)-O(1)
2.170(7)
2.163(7)
1.664(9)
1.674(9)
2.405(4)
2.378(4)
1.486(7)
P(1)-C(25)
P(1)-C(1)
P(2)-O(2)
P(2)-C(26)
P(2)-C(13)
N-C(25)
1.816(7)
1.794(11)
1.497(7)
1.815(11)
1.795(14)
1.435(13)
1.446(14)
N-C(26)
Bond Angles
O(1)-Mo-O(2)
O(1)-Mo-O(3)
O(1)-Mo-O(4)
O(1)-Mo-Cl(1)
O(1)-Mo-Cl(2)
O(2)-Mo-O(3)
O(2)-Mo-O(4)
O(2)-Mo-Cl(1)
O(2)-Mo-Cl(2)
77.3(3)
168.1(3)
89.4(4)
85.0(2)
85.2(2)
90.7(3)
166.8(4)
84.5(2)
84.1(2)
O(3)-Mo-O(4)
O(3)-Mo-Cl(1)
O(3)-Mo-Cl(2)
O(4)-Mo-Cl(1)
O(4)-Mo-Cl(2)
Cl(1)-Mo-Cl(2)
C(26)-N-C(25)
C(26)-N-C(27)
C(25)-N-C(27)
102.5(4)
93.4(3)
94.2(3)
94.5(3)
94.9(3)
166.3(1)
116.3(9)
112.9(9)
116.8(10)
which are deshielded compared to the free ligand while their
31P NMR spectra show single resonances around 29-31 ppm.
The reaction of 2 equiv of Ph2P(O)CH2NHPh (2) with Co-
(NO3)2‚6H2O gave a purple colored octahedral complex, [Co-
(NO3)2{Ph2P(O)CH2NHPh}2] (21). When an ethanolic so-
lution of Co(NO3)2‚6H2O was treated with equimolar quantity
Also, both octahedral and tetrahedral complexes show two
closely spaced weak d-d transitions in the visible region.
The two visible energy bands observed near 520 nm and
528-554 nm of the octahedral complexes 21-23 are
assigned to 4T1g(F) f 4T2g and 4T1g(F) f 4T1g(P) transitions,
respectively. The visible energy transitions of the tetrahedral
complexes 24 and 25 are substantially red shifted (644-
674 nm) with appreciable intensity enhancement compared
to the octahedral complexes 21-23. The observed bands are
n
of (Ph2P(O)CH2)2NR (R ) Et (5), Pr (6)) purple colored,
octahedral chelate complexes of the type [Co(NO3)2-
n
(Ph2P(O)CH2)2NR] (R ) Et (22), Pr (23)) are obtained in
quantitative yield as shown in Scheme 6. In the octahedral
cobalt complexes, the oxygen atoms of the nitrate groups
occupy four coordinating sites and the other two sites are
filled by the oxygen atoms of the phosphine oxides. The 31
P
NMR spectra of the products show broad singlets implying
both the phosphorus atoms are equivalent. Further structural
4
4
4
4
assigned to A2 f T1(P) and A2 f T1(F) transitions.
The reaction of an ethanolic solution of (Ph2P(O)CH2)2-
NEt (5) with molybdic acid in acidic medium gave Mo(VI)
chelate complex cis-[MoO2Cl2{(Ph2P(O)CH2)2NEt-κO,κO}]
(26). The 31P NMR spectrum of complex 26 shows a single
resonance at 38.9 ppm with a coordination shift of 9 ppm.
The structure of the molybdenum complex 26 is confirmed
by a single-crystal X-ray diffraction study. The crystal data
and bond distances and angles are listed in Tables 1 and 5,
respectively. A perspective view of the complex with atomic
numbering scheme is shown in Figure 3. The structure of
26 shows a distorted octahedral environment around Mo in
which the ligand coordinates to the metal in a chelate
bidentate mode via the oxygen centers. Both the oxo ligands
and phosphine oxide are in mutually cis orientations while
the chloro ligands are in mutually trans dispositions. The
Mo-Ooxo bond distances in 26 (1.664(9) and 1.674(9) Å)
fall within the range of 1.63-1.73 Å22 and are comparable
to those in [MoO2X2{Ph3P(O)}2] (X ) Cl and Br) (1.70,
1.67 and 1.69, 1.73 Å)22 but shorter when compared to the
Mo-Ooxo distances observed in [MoO2Cl2(OHCN(CH3)2)2]
1
confirmation for 21-23 comes from H NMR, IR spectra,
and microanalytical data (vide infra).
The reaction of 5 with CoCl2‚6H2O in equimolar ratio in
ethanol leads to the formation of a dark blue tetrahedral
complex, [CoCl2(Ph2P(O)CH2)2NEt] (24). The 31P NMR
spectrum of the compound 24 shows a broad singlet at 34.0
ppm. When CoCl2‚6H2O was treated with 2 equiv of 5 in
the presence of NH4PF6, the tetrahedral ionic complex [Co-
{(Ph2P(O)CH2)2NEt}2](PF6)2 (25) was obtained. The mag-
netic measurements confirm the presence of high-spin Co(II)
centers in complexes 21-25 (see Experimental Section). The
broadening of signals in both 31P NMR and 1H NMR spectra
is due to the presence of paramagnetic Co(II) species.
The electronic spectra of free ligands 2, 5, and 6 and the
complexes 22-25 were recorded in ethanol, while CH2Cl2
was used for recording the spectrum of the complex 21. The
free ligands exhibit n f π* and π f π* transitions in the
UV region near 224 and 266 nm, respectively. The octahedral
(21-23) and the tetrahedral complexes (24 and 25) display
ligand-based transitions in the UV region (222-264 nm).
Inorganic Chemistry, Vol. 42, No. 4, 2003 1277

Priya et al.
(1.68 Å).23 The Mo-Cl(1) bond distance of 2.405(4) Å is
slightly longer than the Mo-Cl(2) (2.378(4) Å) bond
distance. However, both Mo-Cl distances in complex 26
are longer than those observed in tetrahedrally coordinated
MoO2Cl2 (gas-phase structure 2.281(3) Å)24 and in [MoO2-
Cl2(OHCN(CH3)2)2] (2.341(7) Å).23
to be explored. The R-hydroxy phosphine oxides obtained
from these reactions are similar to Horner-Wittig intermedi-
ates in the formation of alkenes from the corresponding
alkylphosphine oxides. Further research to understand the
influence of phosphorus substituents in this type of reaction
is underway in our laboratory.
The O-Mo-O angles show large distortions from 90°
(O(1)-Mo-O(2) ) 77.3(3)°; O(3)-Mo-O(4) ) 102.5(4)°)
similar to analogous Mo(VI) complexes containing Ph3Pd
O.22 The Mo-Ooxo (Mo-O(3) and Mo-O(4)) bond distances
are shorter; the wider angle involves the shorter Mo-O bond
distances and is probably due to the O-O repulsion. The
nonbonding O(3)‚‚‚O(4) distance is 2.604 Å, which is less
than 2.8 Å25 (twice the van der Waals radius of oxygen).
The reaction of 5 with Th(NO3)4‚5H2O affords a 10-
coordinate complex, [Th(NO3)3{(Ph2P(O)CH2)2NEt}2](NO3)-
(27). The 31P NMR spectrum of the complex 27 shows a
single resonance at 40.1 ppm with a coordination shift of
11 ppm. The IR and 1H NMR spectral data and the
microanalytical data for the product 27 support the proposed
structure. The FAB mass spectrum shows m/z at 1364 (100%)
corresponding to the cation.
Experimental Section
All manipulations were performed under rigorously anaerobic
conditions using Schlenk techniques. All the solvents were purified
by conventional procedures and distilled prior to use.26 The
aminophosphines, RN(H)PPh2 (R ) Et, nPr, nBu, Ph27), bis-
(diphenylphosphino)amines, RN(PPh2)2 (R ) H,28 Me, Et, nPr,
nBu, Ph,17 iPr29), Ph2PN(H)CH2CH2N(H)PPh2,27 and bis(diphenyl-
phosphino)piperazine,30 Ph2PN(C2H4)2NPPh2, were prepared ac-
cording to the literature procedures. The H and 31P NMR spectra
1
were recorded using Varian VXR 300 and Bruker AMX 400
spectrometers operating at the appropriate frequencies using tet-
ramethylsilane and 85% H3PO4 as internal and external references,
respectively. Positive shifts lie downfield in all cases. IR spectra
were recorded on a Nicolet Impact 400 FT IR instrument in KBr
disks. The electronic absorption spectra were recorded on a JASCO
V 570 UV-visible spectrometer. Magnetic moment measurements
were carried out on a Faraday balance at 303 K. Microanalyses
were performed on a Carlo Erba model 1112 elemental analyzer.
The FAB mass spectra were recorded on JEOL SX 102/DA-6000
mass spectrometer/data system using argon/xenon (6 kV, 10 mA)
as FAB gas and high-resolution mass spectra (HRMS) on a
MASCPEC (msco/9849) system. Melting points were recorded in
capillary tubes and are uncorrected.
Preparation of Ph2PN(H)C6H11 (1). To a stirring ice-cold
solution of cyclohexylamine (5.8 g, 59 mmol) in n-hexane (100
mL) was added dropwise chlorodiphenylphosphine (5.9 g, 27 mmol)
in n-hexane (40 mL), and the reaction mixture was stirred at room-
temperature overnight. Amine hydrochloride was removed by
filtration, and the filtrate was concentrated and cooled to 0 °C
overnight to give 1 as an analytically pure white crystalline solid.
Yield: 80% (6.1 g, 21 mmol). Mp: 49-51 °C. Anal. Calcd for
C18H22NP: C, 76.29; H, 7.83; N, 4.94. Found: C, 76.31; H, 7.69;
The reaction of the ligand 5 with uranyl nitrate in
equimolar ratio in dichloromethane afforded the 8-coordinate
complex, trans-[UO2(NO3)2{(Ph2P(O)CH2)2-NEt-κO,κO}]
(28) as shown in Scheme 6. The 31P NMR spectrum of the
complex 28 shows a single resonance at 41.8 ppm, which is
considerably deshielded from the free ligand with a coor-
dination shift of 12.3 ppm. The IR spectrum shows νPO at
1175 cm-1 with the low-frequency shift of 14 cm-1 attributed
to the coordination.
1
N, 5.02. IR (KBr disk; cm-1): νNH 3303 s. H NMR (CDCl3): δ
0.95-2.59 (m, cyclohexyl, 11H), 7.21-7.55 (m, phenyl, 10H). 31P-
{1H} NMR (CDCl3): δ 36.1 (s).
Preparation of C6H11N(H)CH2P(O)Ph2 (3). A mixture of 1 (0.5
g, 1.60 mmol) and paraformaldehyde (0.057 g, 1.60 mmol) in
toluene (10 mL) was heated to reflux for 4 h. The solution was
then cooled to room temperature, concentrated to 4 mL, and cooled
to 4 °C, whereupon an analytically pure crystalline product of 3
precipitated out. Yield: 70% (0.153 g, 0.488 mmol). Mp: 86-90
°C. Anal. Calcd for C19H24NOP: C, 72.82; H, 7.72; N, 4.47.
Found: C, 72.94; H, 7.49; N, 4.59. IR (KBr disk; cm-1): νNH 3243
Conclusion
The reactions of both aminophosphines and aminobis-
(phosphines) with paraformaldehyde lead to the insertion of
methylene groups into the P-N bond(s). Similar reactions
with other alkyl and aryl aldehydes afford either P-N
inserted products or R-hydroxy phosphine oxides through
P-N bond cleavage. The reactions of aminobis(phosphines)
with both aromatic and aliphatic aldehydes lead to the
formation of R-hydroxy phosphine oxides through P-N bond
cleavages whereas the reaction with furfural affords P-N
insertion product. These reactions do not depend on the acidic
proton on nitrogen as reported earlier,6 but they mainly
depend on the oxidation state of phosphorus atom. Also, the
reactivity depends on the substituents on nitrogen, but the
influence of phosphorus substituents in these reactions is yet
1
s, νPO 1183 vs. H NMR (CD2Cl2): δ 0.97-2.44 (m, cyclohexyl,
11H), 3.22 (d, 2JPH ) 9.6 Hz, CH2, 2H), 7.2-7.8 (m, phenyl, 10H).
31P{1H} NMR (CD2Cl2): δ 29.9 (s).
General Procedure for the Preparation of RN(CH2P(O)Ph2)2
n
i
n
(R ) Me, Et, Pr, Pr, Bu). To a solution of RN(PPh2)2 (0.50
mmol) in 7 mL of toluene was added paraformaldehyde (1.0 mmol),
and the mixture was heated to reflux for 4 h. The solution was
then cooled to room temperature, solvent was removed under
(28) Noeth, H.; Meinel, L. Z. Anorg. Allg. Chem. 1967, 349, 225.
(29) Balakrishna, M. S.; Prakasha, T. K.; Krishnamurthy, S. S.; Siriwardane,
U.; Hosmane, N. S. J. Organomet. Chem. 1990, 390, 203.
(30) Thomas, C. J.; Rao, M. N. S. Z. Anorg. Allg. Chem. 1993, 619, 433.
1278 Inorganic Chemistry, Vol. 42, No. 4, 2003

Insertion of Carbon Fragments into P(III)-N Bonds
reduced pressure, and the residue obtained was washed with
n-hexane (3 × 5 mL) and then dissolved in a mixture of CH2Cl2-
n-hexane (2:1) and kept at -15 °C for 2 days to give colorless
crystals of the products.
Preparation of Ph2P(O)CH2N(CH2)3NCH2P(O)Ph2 (10). A
mixture of bis(diphenylphosphino)ethylenediamine (0.20 g, 0.44
mmol) and paraformaldehyde (0.028 g, 0.88 mmol) in 7 mL of
toluene was heated under reflux conditions for 4 h. The solution
was then cooled to room temperature, solvent was removed under
reduced pressure, and the residue obtained was washed with hexane
(4 × 3 mL) and redissolved in a mixture of CH2Cl2-hexane (2:1)
to give the crystalline product of 10. Yield: 55% (0.130 g, 0.26
mmol). Mp: 132-134 °C. Anal. Calcd for C29H30N2O2P2: C, 69.59;
H, 6.04; N, 5.60. Found: C, 69.32; H, 6.01; N, 5.33. IR (KBr disk;
MeN(CH2P(O)Ph2)2 (4). Yield: 79% (0.182 g, 0.40 mmol).
Mp: 149-152 °C. Anal. Calcd for C27H27NO2P2: C, 70.58; H,
5.92; N, 3.05. Found: C, 69.17; H, 5.96; N, 3.04. IR (KBr disk;
cm-1): νPO 1189 s. 1H NMR (CD2Cl2): δ 2.62 (s, CH3, 3H), 3.63
2
(d, PCH2N, 4H, JPH ) 6 Hz), 7.20-7.95 (m, phenyl, 10H). 31P-
{1H} NMR (CD2Cl2): δ 29.8 (s). MS (HRMS): m/z 459.5.
EtN(CH2P(O)Ph2)2 (5). Yield: 73% (0.167 g, 0.35 mmol).
Mp: 148-152 °C. Anal. Calcd for C28H29NO2P2: C, 71.03; H,
6.17; N, 2.96. Found: C, 70.48; H, 6.15; N, 3.19. IR (KBr disk;
1
cm-1): νPO 1171 s. H NMR (CDCl3): δ 2.87 (s, CH2, 4H), 3.44
2
(d, PCH2N, 4H, JPH ) 7.19 Hz), 3.59 (s, CH2, 2H), 7.26-7.89
(m, phenyl, 20H). 31P{1H} NMR (CDCl3): δ 28.3 (s).
General Procedure for Preparation of Ph2P(O)CH(R)NHPh
(R ) Ph, OC4H3 (Furfuryl), C6H4OH-o). A mixture of Ph2PN-
(H)Ph (0.400 g, 1.44 mmol) and 1 equiv of aldehyde RCHO (R )
nPr, Ph, OC4H3, C6H4OH-o) was stirred at room temperature for
12 h. The resultant slurry was subjected to vacuum to remove any
volatiles, and the residue obtained was washed with n-hexane (3
× 5 mL) and crystallized in a mixture of CH2Cl2-n-hexane (2:1)
at 0 °C to give analytically pure products.
cm-1): νPO 1189 s. 1H NMR (CDCl3): δ 0.91 (t, CH3, 3H, 3JHH
)
6.95 Hz), 3.06 (q, CH2, 2H, 3JHH ) 6.93 Hz), 3.69 (d, PCH2N, 4H,
2JPH ) 5.86 Hz), 7.20-7.90 (m, phenyl, 10H). 31P{1H} NMR
(CDCl3): δ 29.5 (s).
nPrN(CH2P(O)Ph2)2 (6). Yield: 73% (0.167 g, 0.34 mmol).
Mp: 154-156 °C. Anal. Calcd for C29H35NO2P2: C, 71.45; H,
6.41; N, 2.87. Found: C, 70.81; H, 6.25; N, 2.43. IR (KBr disk;
cm-1): νPO 1178 s. 1H NMR (CDCl3): δ 0.95 (t, CH3, 3H, 3JHH
)
3
Ph2P(O)CH(Ph)N(H)Ph (11). Yield: 81% (0.451 g, 1.17 mmol).
Mp: 197-200 °C (dec). Anal. Calcd for C25H22NOP: C, 78.31;
H, 5.78; N, 3.65. Found: C, 78.01; H, 5.65; N, 3.17. IR (KBr disk;
cm-1): νNH 3387 s, νPO 1177 vs. 1H NMR (CDCl3): δ 5.39 (br m,
NH and CH, NH-D2O exchangeable, 2H), 6.58-7.92 (m, phenyl,
20H). 31P{1H} NMR (CDCl3): δ 32.7 (s). MS (FAB): 384 (m/z +
1).
Ph2P(O)CH(OC4H3)N(H)Ph (12). Yield: 67% (0.360 g, 0.96
mmol). Mp: 202-205 °C. Anal. Calcd for C23H20NO2P: C, 73.98;
H, 5.39; N, 3.75. Found: C, 73.05; H, 5.53; N, 3.40. IR (KBr disk;
cm-1): νNH 3372 s, νPO 1184 vs. 1H NMR (CDCl3): δ 4.95 (br m,
NH, D2O exchangeable, 1H), 5.34 (m, CH, 1H), 6.16-7.88 (m,
phenyl and furfuryl, 18H). 31P{1H} NMR (CDCl3): δ 30.3 (s). MS
(FAB): 374 (m/z + H).
7.25 Hz), 1.67 (sextet, CH2, 2H, JHH ) 7.25 Hz), 3.30 (t, CH2,
2H, 3JHH ) 7.25 Hz), 4.08 (d, PCH2N, 4H, 2JPH ) 5.85 Hz), 7.75-
8.20 (m, phenyl, 10H). 31P{1H} NMR (CDCl3): δ 29.1 (s).
iPrN(CH2P(O)Ph2)2 (7). Yield: 67% (0.152 g, 0.31 mmol).
Mp: 150-154 °C. Anal. Calcd for C29H35NO2P2: C, 71.45; H,
6.41; N, 2.87. Found: C, 70.81; H, 6.25; N, 2.73. IR (KBr disk;
cm-1): νPO 1183 s. 1H NMR (CDCl3): δ 0.83 (d, CH3, 6H, 3JHH
)
2
7.25 Hz), 2.31 (m, CH, 1H), 3.66 (d, PCH2N, 4H, JPH ) 6.18
Hz), 7.75-8.20 (m, phenyl, 10H). 31P{1H} NMR (CDCl3): δ 30.0
(s).
nBuN(CH2P(O)Ph2)2 (8). Yield: 75% (0.165 g, 0.33 mmol).
Mp: 178-180 °C. Anal. Calcd for C30H37NO2P2: C, 71.84; H, 6.63;
N, 2.79. Found: C, 72.16; H, 6.81; N, 2.51. IR (KBr disk; cm-1):
1
3
νPO 1190 s. H NMR (CDCl3): δ 0.72 (t, CH3, 3H, JHH ) 7.32
3
Ph2P(O)CH(C6H4OH-o)N(H)Ph (13). Yield: 89% (0.510 g,
1.28 mmol). Mp: 144-148 °C. Anal. Calcd for C25H22NO2P: C,
75.18; H, 5.55; N, 3.51. Found: C, 74.82; H, 5.32; N, 3.26. IR
Hz), 0.99 (sextet, CH2, 2H, JHH ) 7.5 Hz), 1.25 (m, CH2, 2H),
3
2
2.97 (t, CH2, 2H, JHH ) 7.14 Hz), 3.72 (d, PCH2N, 4H, JPH
)
5.5 Hz), 7.30-7.80 (m, phenyl, 10H). 31P{1H} NMR (CDCl3): δ
29.2 (s).
1
(KBr disk; cm-1): νOH 3390 br s, νNH 3220 s, νPO 1150 vs. H
The reactions of aminophosphines RN(H)PPh2 (R ) Et, nPr, and
nBu) with paraformaldehyde also gave compounds 5, 6, and 8. The
typical procedure is as follows: A solution of RN(H)PPh2 (1.5
mmol) and paraformaldehyde (1.50 mmol) in toluene (7 mL) was
heated to reflux for 5 h. The reaction mixture was cooled to room
temperature, and the solvent was removed under reduced pressure
to give a white residue which was redissolved in a mixture of CH2-
Cl2-n-hexane (2:1) and cooled to -10 °C for 2 days to give
analytically pure samples of 5, 6, and 8 in 70% (0.165 g, 0.31
mmol), 68% (0.247 g, 0.51 mmol), and 66% (0.248 g, 0.50 mmol)
yields, respectively.
NMR (CDCl3): δ 4.83 (br s, NH, D2O exchangeable), 5.46 (dd,
2
3
CH, 1H, JPH ) 12.0 Hz, JHH ) 3.0 Hz), 6.58-7.86 (m, phenyl,
19H). 31P{1H} NMR (CDCl3): δ 37.9 (s).
General Procedure for the Reaction of nPrN(PPh2) with
RCHO (R ) nPr, Ph, OC4H3, C6H4OH-o). A mixture of Ph2PN-
(nPr)PPh2 (0.400 g, 0.94 mmol) and 2 equiv of aldehyde RCHO
(R ) nPr, Ph, OC4H3, C6H4OH-o) was stirred at room temperature
for 24 h. The resultant slurry was subjected to vacuum to remove
any volatiles, and the residue obtained was washed with n-hexane
(3 × 5 mL) and crystallized in a mixture of CH2Cl2-n-hexane (2:
1) at 0 °C to give analytically pure products.
Ph2P(O)CH(OH)CH2CH2CH3 (14). Yield: 41% (0.210 g, 0.77
mmol). Mp: 116-118 °C. Anal. Calcd for C16H19O2P: C, 70.06;
H, 6.98. Found: C, 70.67; H, 6.87. IR (KBr disk; cm-1): νOH 3207
Preparation of Ph2P(O)CH2N(C2H4)2NCH2P(O)Ph2 (9). To a
solution of bis(diphenylphosphino)piperazine (0.20 g, 0.44 mmol)
in 7 mL of toluene was added paraformaldehyde (0.028 g, 0.88
mmol), heated under reflux conditions for 5 h. The solution was
then cooled to room temperature, the solvent was removed under
reduced pressure, and the residue washed with n-hexane (3 × 5
mL) and redissolved in a mixture of CH2Cl2-n-hexane (3:1) to
give the analytically pure product of 9. Yield: 73% (0.160 g, 0.31
mmol). Mp: 238-240 °C (dec). Anal. Calcd for C30H32N2O2P2:
C, 70.03; H, 6.27; N, 5.44. Found: C, 69.48; H, 6.15; N, 5.48. IR
(KBr disk; cm-1): νPO 1184 vs. 1H NMR (CDCl3): δ 2.57 (s, CH2,
4H), 3.19 (d, PCH2N, 2H, 2JPH ) 6.96 Hz), 7.41-7.82 (m, phenyl,
10H). 31P{1H} NMR (CDCl3): δ 27.2 (s).
1
3
s, νPO 1179 vs. H NMR (CDCl3): δ 0.85 (t, CH3, 3H, JHH
)
6.32 Hz), 1.38 (m, CH2, 2H), 1.65 (m, CH2, 2H), 1.73 (br s, OH,
D2O exchangeable, 1H), 4.41 (d, CH, 2H, 2JPH ) 10.32 Hz), 7.43-
7.89 (m, phenyl, 10H). 31P{1H} NMR (CDCl3): δ 31.3 (s).
The compound 14 is also obtained by the treatment of Ph2PN-
(H)Ph (0.400 g, 1.44 mmol) with butyraldehyde (0.104 g, 1.44
mmol) at room temperature. Yield: 89% (0.350 g, 1.28 mmol).
Ph2P(O)CH(OH)Ph (15). Yield: 42% (0.240 g, 0.78 mmol).
Mp: 164-166 °C (dec). Anal. Calcd for C18H17O2P: C, 74.01; H,
5.56. Found: C, 73.66; H, 5.29. IR (KBr disk; cm-1): νOH 3388 s,
Inorganic Chemistry, Vol. 42, No. 4, 2003 1279

Priya et al.
ν
PO 1163 vs. 1H NMR (CDCl3): δ 1.83 (br s, OH, D2O exchange-
concentrated to 5 mL, triturated with few drops of n-hexane, and
kept at room temperature to give the crystalline products.
[Co(O2NO)2{(Ph2P(O)CH2)2NEt}] (22). Yield: 99% (0.230 g,
0.34 mmol). Mp: 150-152 °C (dec). Anal. Calcd for C28H31N3O8P2-
Co‚H2O: C, 49.86; H, 4.63; N, 6.23. Found: C, 49.99; H, 4.49;
2
able), 5.48 (d, CH, 1H, JHH ) 5.24 Hz), 7.13-7.90 (m, phenyl,
15H). 31P{1H} NMR (CDCl3): δ 30.6 (s).
Ph2P(O)CH(OH)C6H4OH-o (16). Yield: 41% (0.250 g, 0.77
mmol). Mp: 90-92 °C. Anal. Calcd for C19H17O3P: C, 70.37; H,
5.28. Found: C, 70.25; H, 5.33. IR (KBr disk; cm-1): νOH 3229
br s, νPO 1139 vs. 1H NMR (CDCl3): δ 4.01 (br s, OH, D2O
1
N, 6.17. IR (KBr disk; cm-1): νNO 1455 s, νPO 1143 s. H NMR
3
(CD3OD): δ 0.68 (br, CH3, 3H), 3.32 (br, CH2, 2H), 3.80 (br,
PCH2N, 4H), 7.43 (br, phenyl, 12H), 7.69 (br, phenyl, 8H). 31P-
{1H} NMR (CD3OD): δ 33.7 (br s). UV-vis [λ (nm) (ꢀ, M-1
cm-1)] (C2H5OH): 528 (20); 520 (21), 264 (5165), 225 (21 907).
µs (303 K): 4.1 µB.
2
exchangeable), 5.45 (d, CH, 1H, JPH ) 5.86 Hz), 6.67-7.82 (m,
phenyl, 14H), 9.65 (br s, OH, D2O exchangeable). 31P{1H} NMR
(CDCl3): δ 37.4 (s).
(Ph2P(O)CH(OC4H3))2NnPr (17). Yield: 37% (0.210 g, 0.34
mmol). Mp: 152-155 °C (dec). Anal. Calcd for C37H35NO4P2: C,
71.72; H, 5.69; N, 2.26. Found: C, 71.65; H, 5.49; N, 2.17. IR
(KBr disk; cm-1): νPO 1187 vs. 1H NMR (CDCl3): δ 0.52 (t, CH3,
3H, 3JHH ) 8.99 Hz), 1.25 (sextet, CH2, 2H, 3JHH ) 8.99 Hz), 2.14
[Co(O2NO)2{(Ph2P(O)CH2)2NnPr}] (23). Yield: 87% (0.201
g, 0.30 mmol). Mp: 174-176 °C. Anal. Calcd for C29H31N3O8P2-
Co: C, 51.95; H, 4.66; N, 6.27. Found: C, 51.73; H, 4.61; N, 6.02.
1
IR (KBr disk; cm-1): νNO 1473 s, νPO 1143 s. H NMR (CD3-
3
3
2
(t, CH2, 2H, JHH ) 8.99 Hz), 5.53 (d, CH, 2H, JPH ) 5.99 Hz.),
6.23-7.91 (m, phenyl and furfuryl, 26H). 31P{1H} NMR (CDCl3):
δ 29.8 (s). MS (FAB): 620 (m/z + H).
OD): δ 0.27 (br, CH3, 3H), 1.01 (br, CH2, 2H), 1.12 (br, CH2,
2H), 3.80 (br, PCH2N, 4H), 7.39 (br, phenyl, 12H), 7.67 (br, phenyl,
8H). 31P{1H} NMR (CD3OD): δ 33.5 (br s). UV-vis [λ (nm) (ꢀ,
M-1 cm-1)] (C2H5OH): 528 (24); 520 (21), 264 (5330), 225
(22 474). µs (303 K): 4.3 µB.
[CoCl2{(Ph2P(O)CH2)2NEt}] (24). CoCl2‚6H2O (0.100 g, 0.40
mmol) in ethanol (10 mL) was added to (Ph2P(O)CH2)2NEt (0.199
g, 0.40 mmol), also in ethanol (10 mL), and the blue solution was
stirred at room temperature for 3 h. The solvent was removed from
the reaction mixture, and the residue was washed with diethyl ether
(3 × 5 mL) to give the product 24. Yield: 60% (0.168 g, 0.25
mmol). Mp: 220-222 °C (dec). Anal. Calcd for C28H29NO4P2-
CoCl2‚4H2O: C, 49.79; H, 5.52; N, 2.07. Found: C, 49.38; H, 5.31;
N, 1.92. IR (KBr disk; cm-1): νPO 1143 s. 31P{1H} NMR (CD3-
OD): δ 34.0 (br s). UV-vis [λ (nm) (ꢀ, M-1 cm-1)] (C2H5OH):
674 (138); 644 (136), 264 (2667), 224 (19 178). µs (303 K): 4.4
µB.
[Co{(Ph2P(O)CH2)2NEt}2](PF6)2 (25). To an ethanolic (5 mL)
solution of CoCl2‚6H2O (0.05 g, 0.20 mmol) was added (Ph2P-
(O)CH2)2NEt (0.198 g, 0.42 mmol), also in ethanol (7 mL), and
the mixture was stirred for 4 h at room temperature. To the reaction
mixture was added NH4PF6 (0.068 g, 0.42 mmol), and the turbid
solution was stirred for a further 4 h at room temperature. The blue
turbid solution was filtered, and solvent was removed from the
filtrate under vacuum to give the light blue colored product 25.
Yield: 61% (0.250 g, 0.193 mmol). Mp: 144-147 °C (dec). Anal.
Calcd for C56H58N2P6O4CoF12: C, 51.90; H, 4.51; N, 2.16. Found:
C, 51.70; H, 4.35; N, 2.06. IR (KBr disk; cm-1): νPO 1180 s. UV-
vis [λ (nm) (ꢀ, M-1 cm-1)] (C2H5OH): 674 (106); 662 (104), 266
(6701), 226 (23 546). µs (303 K): 4.3 µB.
Preparation of [MoO2Cl2{(Ph2P(O)CH2)2NEt}] (26). Molybdic
acid (0.50 g, 3.34 mmol) was dissolved in concentrated hydrochloric
acid (4 mL), and (Ph2P(O)CH2)2NEt (1.64 g, 3.34 mmol) in a
minimum amount of ethanol was added. The precipitated solid was
filtered out and washed with water, dried, and further recrystallized
from dichloromethane at room temperature. Yield: 61% (1.590 g,
2.10 mmol). Mp: 188-190 °C. Anal. Calcd for C28H29NO4P2-
MoCl2‚CH2Cl2: C, 45.99; H, 4.12; N, 1.85. Found: C, 45.68; H,
4.10; N, 1.76. IR (KBr disk; cm-1): νPO 1184 s. 1H NMR
(CDCl3): δ 0.54 (t, CH3, 3H, 3JHH ) 6.98 Hz), 1.98 (q, CH2, 2H,
3JHH ) 6.98 Hz.) 3.98 (s, PCH2N, 2H), 7.11-8.06 (m, phenyl, 20H).
31P{1H} NMR (CDCl3): δ 38.9 (s).
Preparation of Zinc, Cadmium, and Mercury Complexes,
Ph2P(O)CH2NHPh‚MX2 (M ) Zn, Cd; X ) CH3COO- and M
) Hg; X ) I-). To a solution of an appropriate metal precursor
(0.10 g) in methanol (10 mL) was added to a stoichiometric amount
of the ligand also in methanol (5 mL), and the solution was stirred
for overnight. The solvent was removed completely under reduced
pressure, and the residue obtained was washed with hexane to give
the products.
[(Ph2P(O)CH2NHPh)Zn(CH3COO)2] (18). Yield: 82% (0.191
g, 0.37 mmol). Mp: 114-117 °C. Anal. Calcd for C23H24NO5-
PZn‚H2O: C, 54.29; H, 5.15; N, 2.75. Found: C, 54.26; H, 4.97;
N, 2.65. IR (KBr disk; cm-1): νOH 3329 br, νNH 3242 s, νCO 1600
1
s, νPO 1169 s. H NMR (CDCl3): δ 2.03 (s, CH3, 3H), 3.95 (d,
PCH2N, 2H, 2JPH ) 8.40 Hz), 4.41 (br s, NH, 1H), 7.49-7.93 (m,
phenyl, 15H). 31P{1H} NMR (CDCl3): δ 30.4 (s).
[(Ph2P(O)CH2NHPh)Cd(CH3COO)2] (19). Yield: 70% (0.150
g, 0.26 mmol). Mp: 74-76 °C. Anal. Calcd for C23H24NPO5Cd‚
2H2O: C, 48.14; H, 4.92; N, 2.44. Found: C, 48.03; H, 4.78; N,
2.64. IR (KBr disk; cm-1): νOH 3323 br s, νNH 3242 s, νCO 1600
1
s, νPO 1167 s. H NMR (CDCl3): δ 2.05 (s, CH3, 3H), 3.94 (m,
PCH2N, 2H), 6.65-7.83 (m, phenyl, 15H). 31P{1H} NMR
(CDCl3): δ 29.8 (s).
[(Ph2P(O)CH2NHPh)HgI2] (20). Yield: 95% (0.160 g, 0.21
mmol). Mp: 106-109 °C. Anal. Calcd for C19H18NOPHgI2: C,
29.96; H, 2.38; N, 1.84. Found: C, 29.78; H, 2.43; N, 1.85. IR
(KBr disk; cm-1): νNH 3348 s, νPO 1143 s. H NMR (CDCl3): δ
1
3.94 (d, PCH2N, 2H, 2JPH ) 11.7 Hz), 6.74-7.91 (m, phenyl, 15H).
31P{1H} NMR (CDCl3): δ 29.8 (s).
Preparation of [Co(O2NO)2{Ph2P(O)CH2N(H)Ph}2] (21). To
an ethanolic solution (5 mL) of (Co(NO3)2‚6H2O (0.050 g, 0.17
mmol) was added Ph2P(O)CH2NHC6H5 (0.106 g, 0.340 mmol) also
in ethanol (10 mL), and the mixture was stirred for 2 h at room
temperature. The resultant purple colored solution was evaporated
to dryness and washed with n-hexane (3 × 5 mL) to get crystalline
product 21. Yield: 81% (0.110 g, 0.138 mmol). Mp: 128-131 °C
(dec). Anal. Calcd for C38H34N4O8P2Co: C, 57.22; H, 4.55; N, 7.02.
Found: C, 56.69; H, 4.66; N, 6.96. IR (KBr disk; cm-1): νNH 3369
br m, νNO 1435 s, νPO 1163 s. UV-vis [λ (nm) (ꢀ, M-1 cm-1)]
(CH2Cl2): 544 (71); 520 (49), 289 (7892), 243 (40 588), 222
3
(61 274). µs (303 K): 4.2 µB.
Preparation of [Th(NO3)3{(Ph2P(O)CH2)2NEt}2]NO3 (27). A
solution of the dioxide EtN(CH2P(O)Ph2)2 (0.166 g, 0.35 mmol)
in ethanol (5 mL) was added to a solution of Th(NO3)4‚5H2O (0.100
g, 0.17 mmol) also in ethanol (10 mL). The clear solution was
allowed to stir at room temperature for 4 h, during which time the
product precipitated out was filtered and dried. The product was
Preparation of [Co(O2NO)2{(Ph2P(O)CH2)2NR}] (R ) Et,
nPr). (Co(NO3)2‚6H2O (0.100 g, 0.34 mmol) in ethanol (7 mL) was
combined with 2 equiv of the ligand (Ph2P(O)CH2)2NR (R ) Et,
nPr) also in ethanol (10 mL), and the purple colored solution was
stirred at room temperature for 2 h. The reaction mixture was
1280 Inorganic Chemistry, Vol. 42, No. 4, 2003

Insertion of Carbon Fragments into P(III)-N Bonds
recrystallized from CH2Cl2-diethyl ether (1:1) mixture. Yield: 80%
(0.200 g, 0.14 mmol). Mp: 141-144 °C. Anal. Calcd for
C56H68N6O16P4Th: C, 47.13; H, 4.09; N, 5.89. Found: C, 47.25;
data collection are given in the Tables 1 and 4. The data were
corrected for Lorentz and polarization effects.32 The calculations
were performed with the SHELXTL PLUS33 program package for
the compounds 4, 8, and 26, whereas for the compounds 6 and 14
the structures were solved by direct methods (SHELXS-97) and
refined using SHELXL-97 software.34 The non-hydrogen atoms
were geometrically fixed and allowed to refine using riding model.
For 26, an empirical (ψ-scans) absorption correction was em-
ployed.35
H, 3.98; N, 6.05. IR (KBr disk; cm-1): νNO 1519 s, νPO 1134 s.
3
3
1H NMR (CDCl3): δ 0.41 (t, CH3, 3H, JHH ) 6.59 Hz), 1.75 (q,
3
CH2, 2H, JHH ) 6.59 Hz), 3.90 (s, PCH2N, 4H), 7.26-7.72 (m,
phenyl, 20H). 31P{1H} NMR (CDCl3): δ 40.1 (s). MS (FAB): 1364
(m/z - 1).
Preparation of [UO2(NO3)2{(Ph2P(O)CH2)2NEt}] (28). A
solution of the ligand EtN(CH2P(O)Ph2)2 (0.047 g, 0.09 mmol) in
CH2Cl2 (10 mL) was added to UO2(NO3)2 (0.050 g, 0.09 mmol)
also in CH2Cl2 (10 mL), and the reaction mixture was stirred at
room temperature for 12 h, during which time an analytically pure
yellow crystalline product was separated from the reaction mixture.
The product was isolated by filtration and dried under vacuum.
Yield: 52% (0.045 g, 0.052 mmol). Mp: 199-200 °C (dec). Anal.
Calcd for C28H29N3O10P2U: C, 38.77; H, 3.37; N, 4.84. Found:
Acknowledgment. Council of Scientific and Industrial
Research (CSIR), New Delhi, is acknowledged for the
financial support of this work. S.P. is thankful to the CSIR,
New Delhi, for JRF and SRF fellowships. We thank the
National Single-Crystal X-ray Diffraction facility, IIT Bom-
bay, and the Chemistry Department, Tulane University, for
the support of the Crystallography Laboratory. We also thank
the Regional Sophisticated Instrumentation Center (RSIC),
Bombay, Sophisticated Instrumentation facility (SIF), Ban-
galore, India, for NMR spectra and RSIC, Lucknow, India,
and the Department of Chemistry, University of Alberta,
Edmonton, Canada, for mass spectra.
C, 38.43; H, 3.62; N, 4.58. IR (KBr disk; cm-1): νNO 1439 s, νPO
3
1
3
1175 s. H NMR (CDCl3): δ 0.76 (t, CH3, 3H, JHH ) 8.00 Hz),
3
2.39 (q, CH2, 2H, JHH ) 8.00 Hz), 4.06 (s, PCH2N, 4H), 7.26-
8.16 (m, phenyl, 20H). 31P{1H} NMR (CDCl3): δ 41.8 (s).
X-ray Crystallography. Crystals of the compounds 4, 6, 8, 14,
and 26 obtained as described above were mounted on Pyrex
filaments with epoxy resin. An Enraf-Nonius CAD-4 diffractometer
(for compound 26) and Nonius MACH3 diffractometer (for the
compounds 4, 6, 8, and 14) were used for the unit cell determination
and intensity data collection. The initially obtained unit cell
parameters were refined by accurately centering randomly selected
reflections. General procedures for crystal alignment and collection
of intensity data on the Enraf-Nonius CAD-4 diffractometer have
been published.31 The initial orthorhombic cell obtained by the
CAD-4 software for 26 was confirmed by the observation of mmm
diffraction symmetry. Periodic monitoring of check reflections
showed stability of the intensity data. Details of the crystal and
Supporting Information Available: X-ray crystallographic files
in CIF format for the structure determinations of MeN(CH2P(O)-
Ph2)2 (4), nPrN(CH2P(O)Ph2)2 (6), nBuN(CH2P(O)Ph2)2 (8),
Ph2P(O)CH(OH)CH2CH2CH3 (14), and [MoO2Cl2{(Ph2P(O)CH2)2-
NEt}] (26). This material is available free of charge via the Internet
at http://pubs.acs.org.
IC026118T
(32) Burla, M. C.; Camalli, M.; Cascarano, G.; Giacovazzo, C.; Polidori,
G.; Spagna, R.; Viterbo, D. J. Appl. Crystallogr. 1989, 22, 389.
(33) SHELXTL PLUS, version 5.1; Bruker AXS: Madison, WI, 1995.
(34) Sheldrick, G. M. SHELXL-97. Program for crystal structure refine-
ment; University of Gottingen: Gottingen, Germany, 1997.
(31) Harms, K.; Wocadlo, S. Program to Extract Intensity Data from Enraf-
Nonius CAD-4 Files; University of Marburg: Marburg, Germany,
1987.
(35) Mague, J. T.; Lloyd, C. L. Organometallics 1988, 7, 983.
Inorganic Chemistry, Vol. 42, No. 4, 2003 1281