Facile syntheses of new multidentate (phosphino)amines: X-ray structure of

Article abstract of DOI:10.1016/S0022-328X(02)02025-9

The rigid backbone tetradentate (phosphino)amines 1,4-{(Ph₂P)₂N}₂C₆H ₄, 1,4-{(Ph₂P)₂NCH₂} ₂C₆H₄ and the unprecedented octadentate liga

Full text of DOI:10.1016/S0022-328X(02)02025-9

Journal of Organometallic Chemistry 664 (2002) 294ꢂ297
/
www.elsevier.com/locate/jorganchem
Facile syntheses of new multidentate (phosphino)amines: X-ray
structure of 1,4-{(OC) Mo(Ph P) NCH } C H
4
2
2
2 2 6 4
a
a,
b,1
Kirsty G. Gaw , Martin B. Smith ꢀ, Jonathan W. Steed
a
Department of Chemistry, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK
b
Department of Chemistry, King’s College London, Strand, London WC2R 2LS, UK
Received 3 September 2002; accepted 30 September 2002
Abstract
The rigid backbone tetradentate (phosphino)amines 1,4-{(Ph P) N} C H , 1,4-{(Ph P) NCH } C H and the unprecedented
2
2
2
6
4
2
2
2
2
6
4
octadentate ligand 1,2,4,5-{(Ph
2
P)
2
NCH
PCl in Et
norbornadiene) afforded either binuclear or tetranuclear P,P?-chelate complexes; the X-ray structure of
2
CH
2
SCH
2
}
4
C
6
H
2
were readily prepared, in one-step, by full phosphinylation of the
appropriate primary amine with Ph
2
2
O with NEt
3
as auxiliary base. Reaction with stoichiometric amounts of
4
[
one example is presented.
Mo(CO) (h -nbd)] (nbdꢁ
/
4
#
2002 Elsevier Science B.V. All rights reserved.
Keywords: Amines; Carbonyl complexes; Crystal structure; Molybdenum; NMR spectroscopy; Phosphorus ligands
1
. Introduction
synthesis of two new keto-functionalised (phosphino)a-
mines and demonstrated that these co-ordinated ligands
The co-ordination and organometallic chemistry of
undergo remarkably clean s(C 2-H) bond activation
sp
phosphorus bearing ligands possessing one (or more) Pꢂ
N bond(s) has received some attention especially of late
1]. Potentially this ligand family is extremely attractive
since preparative routes enable access to various struc-
tural modifications via simple PꢂN bond formation.
/
affording novel five-membered metallacycles [5].
One fascinating class of tertiary polyphosphine ligand
that has attracted considerable recognition of late are
[
dendrimers terminally coated with ꢂ{PR2}n groups,
/
/
since they constitute excellent scaffolds for metalloden-
drimer construction [6]. We are interested in developing
synthetic routes to (phosphino)amine coated dendrimers
Although poorly exploited in catalysis, with respect to
tertiary phosphines and phosphites, phosphorus(V)
derivatives [2] or complexes (generated in situ or
performed) stabilised by such ligands are effective in
several catalytic reactions [1b,c,f,3]. Asymmetric cataly-
given the useful catalytic properties of PꢂN containing
/
ligands. However, prior to this work, surprisingly few
studies of simple model compounds such as bi- or
polydentate (phosphino)amines have been documented
sis with chiral variants incorporating an aminoꢂphos-
/
phine functionality have also been described [4]. Our
interest in this unique class of ligand stems from the
systematic control of stereoelectronic factors by subtle
manipulation of the R group(s) either on the phospho-
rus or nitrogen precursors. Recently we reported the
[
7]. Accordingly we describe here convenient, high
yielding syntheses of new tetradentate and octadentate
phosphino)amines by multiple phosphinylations. Stoi-
(
4
chiometric reaction of these ligands with [Mo(CO) (h -
4
nbd)] affords either binuclear [1,4-{(OC) Mo(Ph P) -
N} C H ], [1,4-{(OC) Mo(Ph P) NCH } C H ] or
4
2
2
2
6
4
4
2
2
2 2
6
4
ꢀ
E-mail addresses: m.b.smith@lboro.ac.uk (M.B. Smith),
Corresponding author. Fax: ꢃ
/
44-1509-223-925
tetranuclear
CH } C H ] molybdenum(0) complexes, respectively.
[1,2,4,5-{(OC) Mo(Ph P) NCH CH S-
4 2 2 2 2
2
4
6
2
jon.steed@kcl.ac.uk (J.W. Steed).
1
To whom correspondence regarding the crystallographic study
Spectroscopic and single-crystal X-ray diffraction stu-
dies are reported.
should be addressed. Fax: ꢃ44-20-7848-2810.
/
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 2 0 2 5 - 9

K.G. Gaw et al. / Journal of Organometallic Chemistry 664 (2002) 294ꢂ
/297
295
2
. Results and discussion
The synthesis of the rigid backbone (phosphino)a-
mines 1 and 2 was based on reaction of commercially
available 1,4-(H N) C H or 1,4-(H NCH ) C H and
four equivalents of Ph PCl in Et O with NEt (Scheme
2
2
6
4
2
2 2
6
4
2
2
3
1
{
). This synthetic procedure circumvents the use of 1,4-
(Cl P) N} C H as starting material which reportedly
2
2
2
6
4
involves prolonged reflux and proceeds in low (13%)
yield [8]. Compounds 1 and 2 were isolated, after
workup, in excellent yields (77 and 96%, respectively)
as white or off-white solids and were characterised by
3
1
1
1
2
31
1
P{ H}- and H-NMR spectroscopy. The P{ H}-
NMR spectra both display single P resonances at d(P)
7
0.2 (for 1) and d(P) 60.6 ppm (for 2) and, in the case of
, similar to that found for the closely related system
1
1
Ph P) NPh [d(P) 68.8 ppm]. The H-NMR spectra
(
2
2
exhibit no NH resonances and in full accord with
complete NꢂH substitution. Using the same procedure
we also synthesised (in 95% yield) the novel octapodal
ligand 1,2,4,5-{(Ph P) NCH CH SCH } C H (3)
Scheme 2) from the known tetraamine precursor
/
2
2
2
2
2 4
6
2
(
3
1
1
1
NMR spectrum (at 101.3 MHz) showed a single, sharp
,2,4,5-{H NCH CH SCH } C H [9]. The P{ H}-
2 2 2 2 4 6 2
4
Scheme 1. (i) 4 Ph
2
PCl, NEt
3
, Et
2
O; (ii) 2 [Mo(CO)
4
(h -nbd)].
resonance at d(P) 61.5 ppm indicating a remarkably
clean eightfold Nꢂ
evidence for any partially substituted products was
1
observed. The simplicity of the H-NMR spectrum of
/
H to NꢂPPh transformation. No
/
2
lised dendrimers. This procedure should bode well for
the rapid construction of new dendrimeric materials.
In order to probe the ligating behaviour of the ligands
3
, coupled with the absence of any NH resonances,
1
ꢂ
/
3 we chose to prepare the organic soluble molybde-
provides further testimony for a highly symmetrical
structure and no defect species present. Ligand 3 is
unique and may be viewed as a prototype of a much
broader family of (phosphino)amine surface-functiona-
num(0) tetracarbonyl complexes 4ꢂ6 (Schemes 1 and 2).
/
4
Hence treatment of [Mo(CO) (h -nbd)] with either 0.5
4
equivalents (for 1 and 2) or 0.25 equivalents (for 3) of
(phosphino)amine in dichloromethane gave the corre-
2
A typical synthesis is illustrated here for compound 2. To a stirred
3
suspension of 1,4-(H
6.27 mmol) and Et
30 ml) was added dropwise over 30 min whilst the temperature was
maintained at ca. 0 8C. After the addition of further Et O (40 ml) the
mixture was stirred for ca. 3 days. The solvent was evaporated to
dryness under reduced pressure and degassed distilled water (50 ml)
added. The solid was filtered by suction filtration, washed with
2
NCH
2
)
2
C
6
H
4
(1.25 g, 9.18 mmol) in NEt
3
(3.67 g,
A typical synthesis is illustrated here for compound 4. 1,4-
3
2
O (100 ml), Ph
2
PCl (8.70 g, 39.43 mmol) in Et
2
O
2 2 2 6 4
{(Ph P) N} C H (0.070 g, 0.0828 mmol) was added to a solution of
4
(
2 2 4
CH Cl (20 ml) and [Mo(CO) (h -nbd)] (0.050 g, 0.167 mmol). The
2
solution was stirred for 30 min and the volume reduced in vacuo to ca.
1ꢂ2 ml. The addition of Et O (20 ml) and petroleum ether (b.p. 60ꢂ
80 8C, 10 ml) gave a solid which was collected by suction filtration,
washed with petroleum ether (b.p. 60ꢂ80 8C, 5 ml) and dried in vacuo.
Yield: 0.090 g, 86%. Anal. Calc. (Found) for C62H44N P O Mo : C,
/
2
/
/
distilled water (50 ml), hexane (2ꢄ
Yield: 7.68 g, 96%. Anal. Calcd. (Found) for C56
6.26 (76.26); H, 5.61 (5.50); N, 3.18 (3.24)%. Selected sprectroscopic
/
50 ml) and absolute EtOH (75 ml).
2
4
8
2
.
H
48
N
2
P
4
0.5H
2
O: C,
59.06 (59.56); H, 3.52 (3.63); N, 2.22 (2.14)%. Selected spectroscopic
1
7
data: H-NMR (250 MHz, CDCl ): d 7.43ꢂ
6 5 2
/7.21 [ꢂ/P(C H ) ], 6.02
3
1
31
[C H ]. P{ H} NMR (36.2 MHz, CDCl ): d 95.2 ppm. IR (KBr): n
1
data: H-NMR (250 MHz, CDCl
3
3
): d 7.31ꢂ
/
7.20 [ꢂ
/
P(C
6 5 2
H ) ], 6.45
6
4
3
31
1
ꢅ1
[
CDCl
C
6
H
4
], 4.36 [ J(PH) 21.0 Hz, CH
): d 60.6. IR (KBr): n 2852 (alkyl CH), 863 (PN) cm . FAB
2
]. P{ H}-NMR (36.2 MHz,
ꢅ1
2019, 1929, 1902, 1880 (CO), 936, 911 (PN) cm . FABMS: m/z 1261
ꢃ
3
2
8
4
2 2 2
[M ]. For 5: Anal. Calc. (Found) for C64H48N O P Mo ×0.25CH Cl :
/
ꢃ
1
C, 58.90 (58.50); H, 3.74 (3.67); N, 2.14 (2.15)%. H-NMR (250 MHz,
MS: m/z 873 [M ] in addition to 889 [Mꢃ
/1O], 905 [Mꢃ
/
2O], 921
3
[
Mꢃ
/
3O] and 937 [Mꢃ
/
4O]. For 1: Anal. Calc. (Found) for
CDCl ): d 7.44ꢂ
/
/
6 5 2 6 4
7.28 [ꢂP(C H ) ], 5.82 [C H ], 3.92 [ J(PH) 20 Hz
3
.
31
CH2]. P{ H}-NMR (36.2 MHz, CDCl ): d 95.8 ppm. IR (KBr): n
1
C
54
H
44
N
2
1
P
4
0.5H
2
O: C, 75.95 (75.58); H, 5.32 (5.14); N, 3.28
3
(
3.25)%. H-NMR (250 MHz, CDCl
3
): d 7.26ꢂ
]. P{ H}-NMR (36.2 MHz, CDCl ): d 70.2. IR (KBr): n
29 (PN) cm . FAB MS: m/z 844 [M ]. For 3: Anal. Calc. (Found)
3H O: C, 69.78 (69.75); H, 5.77 (5.48); N, 2.86
2.98)%. H-NMR (250 MHz, CDCl ): d 7.35ꢂ7.24 [ꢂP(C ], 6.79
]. P{ H}-NMR (100.6 MHz, CDCl ): d
/
7.13 [ꢂ
/
6 5 2
P(C H ) ],
2850 (alkyl CH), 2016, 1921, 1894, 1878 (CO), 840 (PN) cmꢅ1.
3
1
1
ꢃ
5
.99 [C
6
H
4
3
FABMS: m /z 1289 [M ]. For 6: Anal. Calc. (Found) for
C130H106N O P S Mo : C, 56.98 (57.13); H, 3.90 (4.25); N, 2.04
ꢅ1
ꢃ
9
4
16
8
4
4
1
for C114
H
N
106 4
P
8
S
4
×
/
2
(1.84)%. H-NMR (250 MHz, CDCl ): d 7.49ꢂ
/
/
6 5 2
7.35 [ꢂP(C H ) ], 6.28
3
1
31
1
(
3
/
/
6
H
5
)
2
6 2 2 3
[C H ], 3.07, 1.89, 1.60 [CH ]. P{ H}-NMR (36.2 MHz, CDCl ): d
31
1
91.2 ppm. IR (KBr): n 2020, 1926, 1899, 1882 (CO), 844 (PN) cmꢅ1.
FABMS: m/z 2740 [Mꢃ].
[
C
6
H
2
], 3.46, 3.29, 2.00 [CH
2
3
ꢅ1
ꢃ
6
1.5. IR (KBr): n 844 (PN) cm . FABMS: m/z 1909 [M ].

296
K.G. Gaw et al. / Journal of Organometallic Chemistry 664 (2002) 294ꢂ297
/
3
sponding molybdenum complexes 4ꢂ6 in good yields.
/
In all cases a single downfield resonance at ca. d(P) 95
ppm was observed and in a region similar to that of the
mononuclear complex [Mo(CO) {(P,P?-Ph P) NPh}]
4
2
2
(
7) [d(P) 94.4 ppm]. The infrared spectra of 4ꢂ
/6 show
four intense n(CO) bands, typically in the region 2020ꢂ
/
ꢅ1
1
878 cm , consistent with a cis tetracarbonylmolyb-
denum fragment [7]. The FAB mass spectral data for 4ꢂ
/
6
1
each showed a molecular ion peak at m/z 1261 (for 4),
289 (for 5) and 2740 (for 6).
Crystals of 5 suitable for a single crystal X-ray
4
diffraction study were obtained by slow diffusion of
Et Oꢃ
/
petroleum ether (b.p. 60ꢂ
/
80 8C) into a CDCl ꢃ
/
2
3
CH Cl over several days. The structure (Fig. 1)
confirms the binuclear arrangement with two cis
Mo(CO) ’ metal fragments P,P?-ligated by the tetra-
2
2
‘
4
dentate ligand 2. The molecule is situated across an
inversion centre. The four-membered MoꢂPꢂNꢂP ring
is non planar [the dihedral angle between the Mo(1)ꢂ
P(1)ꢂP(2) and P(1)ꢂN(1)ꢂP(2) planes is 15.78] and
roughly symmetrical. Within the metalloring the Moꢂ
P and PꢂN distances are comparable to those previously
reported [7]. Furthermore, the MoꢂC bond lengths
trans to 2 [both 2.000(2) A] are marginally shorter
/
/
/
/
/
/
/
/
/
/
˚
˚
than those of Mo(1)ꢂ
[
/
C(3) [2.047(2) A] and Mo(1)ꢂ
2.037(2) A]. The axial CO ligands are slightly distorted
C(3)ꢂMo(1)ꢂC(4) 172.02(9)8] and as expected if there
/
C(4)
˚
[
/
/
exists substantial intragroup repulsions between C(3)ꢂ
/
O(3)/C(4)ꢂO(4) and two phenyl groups of the co-
/
ordinated ligand 2. Crystals of 4 have also been isolated
but the poor crystal quality precluded an accurate
structure determination. Nevertheless the refinement
again clearly indicates that the gross structure comprises
a binuclear structure with two ‘Mo(CO) ’ moieties
4
linked via a bridging 1,4-{(Ph P) N} C H ligand [10].
4
2
2
2
6
3
. Conclusions
The proficient syntheses of three new di- and
poly(phosphino)amines and their complexation to a
4
Scheme 2. (i) 8 Ph
2
PCl, NEt
3
, Et
2
O; (ii) 4 [Mo(CO)
4
(h -nbd)].
strated for the first time. It is envisaged that this
procedure for ligand construction and subsequent metal
co-ordination be extended to the synthesis of cascade
molecules bearing greater numbers of peripheral coated
zerovalent molybdenum precursor has been demon-
4
Crystal data for complex 5: C64
H
48Mo
2
N
2
8
O P
4
, Mꢁ
17.1998(4), cꢁ
5810.4(3) A , Zꢁ 4, mꢁ0.559
100(2) K. Data were collected on a Nonius Kappa CCD
diffractometer. Of a total of 18890 reflections collected, 6639 were
independent (Rint 0.0507). R 0.0323 [I ꢀ2s(I)], wR 0.0711.
/1288.80,
monoclinic, space group C2/c, aꢁ
/
18.4183(6), bꢁ
/
/
/
ꢂ
/
N(PR ) [or ꢂN(H)PR ] functionalities. Further ligand
/
3
2 2
2
˚
˚
1
8.5880(6) A, bꢁ
/
99.3450(10)8, Uꢁ
/
/
ꢅ1
and complexation studies towards catalytically benefi-
cial metals (e.g. Ru, Rh, Pd) are in progress and will be
reported in due course.
mm , Tꢁ
/
ꢁ/
1
ꢁ/
/
2
ꢁ/
The structure was solved using SHELXS-97 [11] and developed via
alternating least square cycles and difference Fourier synthesis
(
SHELXL-97) [11] with the aid of the program XSEED [12]. All non-
hydrogen atoms were modelled anisotropically, while hydrogen atoms
are assigned an isotropic thermal parameter 1.2 times that of the
parent atom (1.5 for terminal atoms) and allowed to ride. All
calculations were carried out with either a Silicon Graphics Indy
workstation or an IBM compatible PC.
4
. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic

K.G. Gaw et al. / Journal of Organometallic Chemistry 664 (2002) 294ꢂ
/297
297
˚
Fig. 1. The X-ray structure of 5. Selected bond distances (A) and angles (8): Mo(1)ꢂ
Mo(1)ꢂC(2) 2.000(2), Mo(1)ꢂC(3) 2.047(2), Mo(1)ꢂC(4) 2.037(2), P(1)ꢂN(1) 1.718(1), N(1)ꢂ
Mo(1)ꢂC(3) 99.70(7), P(1)ꢂMo(1)ꢂC(4) 87.87(6), P(1)ꢂMo(1)ꢂC(1) 162.74(7), P(1)ꢂMo(1)ꢂC(2) 100.18(7), P(2)ꢂ
Mo(1)ꢂC(4) 95.19(6), P(2)ꢂMo(1)ꢂC(1) 100.61(7), P(2)ꢂMo(1)ꢂC(2) 164.62(7), C(3)ꢂMo(1)ꢂC(4) 172.02(9), Cꢂ
4.63(9), Mo(1)ꢂP(1)ꢂN(1) 93.81(6), Mo(1)ꢂP(2)ꢂN(1) 94.91(6), P(1)ꢂN(1)ꢂP(2) 103.93(9).
/
P(1) 2.5185(6), Mo(1)ꢂ
/
P(2) 2.4940(6), Mo(1)ꢂ
Mo(1)ꢂ
Mo(1)ꢂ
Mo(1)ꢂ
/
C(1) 2.000(2),
/
/
/
/
/P(2) 1.708(1). P(1)ꢂ
/
/
P(2) 65.14(1), P(1)ꢂ
C(3) 90.34(7), P(2)ꢂ
C range 83.68(9)ꢂ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
9
/
/
/
/
/
/
(
f) J. Liedtke, H. R u¨ egger, S. Loss, H. Gr u¨ tzmacher, Angew.
Chem. Int. Ed. Engl. 39 (2000) 2478.
Data Centre, CCDC no. 191805. Copies of this infor-
mation may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge CB2
[
[
2] (a) M. Shi, W.-S. Sui, Tetrahedron: Asymmetry 11 (2000) 835;
(b) M. Shi, W.-S. Sui, Tetrahedron: Asymmetry 10 (1999) 3319.
3] (a) S.C. van der Slot, P.C.J. Kamer, P.W.N.M. van Leeuwen, J.
1
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
EZ, UK (Fax: ꢃ44-1223-336033; e-mail: deposit@
/
Fraanje, K. Goubitz, M. Lutz, A.L. Spek, Organometallics 19
(
(
2000) 2504;
b) J.M. Brunel, A. Heumann, G. Buono, Angew. Chem. Int. Ed.
Engl. 39 (2000) 1946;
Acknowledgements
(c) A. Wegner, W. Leitner, Chem. Commun. (1999) 1583.
4] (a) K. Hiroi, Y. Suzuki, I. Abe, R. Kawagishi, Tetrahedron 56
[
(
(
(
2000) 4701;
We should like to thank the EPSRC for a studentship
K.G.G.), Infineum UK Ltd. and The Leverhulme Trust
b) F.-Y. Zhang, C.-C. Pai, A.S.C. Chan, J. Am. Chem. Soc. 120
1998) 5808;
(
for funding. Fast atom bombardment (FAB) mass
spectra were run by the EPSRC mass spectrometry
service at Swansea. The EPSRC and King’s College
London are gratefully acknowledged for the provision
of the X-ray diffractometer and the Nuffield Founda-
tion for the provision of computing equipment.
(c) I.C.F. Vasconcelos, N.P. Rath, C.D. Spilling, Tetrahedron:
Asymmetry 9 (1998) 937.
5] K.G. Gaw, A.M.Z. Slawin, M.B. Smith, Organometallics 18
[
[
(
1999) 3255.
6] (a) For two recent examples, see: D. de Groot, B.F.M. de Waal,
J.N.H. Reek, A.P.H.J. Schenning, P.C.J. Kramer, E.W. Meijer,
P.W.N.M. van Leeuwen, J. Am. Chem. Soc. 123 (2001) 8453;
(
b) S.C. Bourque, H. Alper, L.E. Manzer, P. Arya, J. Am. Chem.
Soc. 122 (2000) 956.
7] (a) E. Lindner, M. Mohr, C. Nachtigal, R. Fawzi, G. Henkel, J.
[
References
Organomet. Chem. 595 (2000) 166;
(
b) T.Q. Ly, A.M.Z. Slawin, J.D. Woollins, J. Chem. Soc. Dalton
[
1] (a) For recent examples, see: E.J. Sekabunga, M.L. Smith, T.R.
Webb, W.E. Hill, Inorg. Chem. 41 (2002) 1205;
Trans. (1997) 1611.
[8] A.R. Davies, A.T. Dronsfield, R.N. Haszeldine, D.R. Taylor, J.
Chem. Soc. Perkin I (1973) 379.
(
b) S.J. Dossett, A. Gillon, A.G. Orpen, J.S. Fleming, P.G.
Pringle, D.F. Wass, M.D. Jones, Chem. Commun. (2001) 699;
c) M. Rodriguez, I. Zubiri, M.L. Clarke, D.F. Foster, D.J. Cole-
[9] P. Comba, J. Ensling, P. G u¨ tlich, A. K u¨ hner, A. Peters, H.
Pritzkow, Inorg. Chem. 38 (1999) 3316.
(
Hamilton, A.M.Z. Slawin, J.D. Woollins, J. Chem. Soc. Dalton
Trans. (2001) 969;
[10] K.G. Gaw, A.M.Z. Slawin, M.B. Smith, Unpublished work.
[11] G.M. Sheldrick, SHELXL-97, University of G o¨ ttingen, Germany,
1997.
(d) M.L. Clarke, D.J. Cole-Hamilton, A.M.Z. Slawin, J.D.
Woollins, Chem. Commun. (2000) 2065;
[12] L.J. Barbour, XSEED, A program of the Manipulation and
Display of Crystallographic Models, University of Missouri,
Columbia, 1999.
(
(
e) K.G. Gaw, A.M.Z. Slawin, M.B. Smith, New J. Chem. 24
2000) 429;