Spectroscopic and structural characterization of O,O′-(diphenylphosphineoxide)amidate and acetylacetonate complexes of pentacoordinate nickel(II)

Article abstract of DOI:10.1016/j.jorganchem.2008.09.075

Heteroleptic nickel pentacoordinate complexes with the macrocyclic ligands 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene (Me₃-mcN₃) or its 9-methyl derivative (Me₄-mcN₃), as ancillary ligands, and O,O′-(diphenylphosphineoxide)amidate ligands, [RC(O)NP(O)Ph₂]^? (R = C₆H₆ (1), C₅H₄N (2), C₄H₃S (3)), have been prepared as well as related acetylacetonate derivatives. The complexes have been studied by spectroscopic methods (IR, UV-Vis and ¹H NMR). In acetone solution, the complexes exhibit isotropically shifted ¹H NMR resonances. The full assignment of these resonances has been achieved using one- and two-dimensional ¹H NMR techniques. The single-crystal structures of {(Me₄-mcN₃)Ni[OP(Ph₂)NC(Tf)O]}[PF₆] (9) and {(Me₃-mcN₃)Ni(acac)}[PF₆] (10) have been established by X-ray diffraction.

Full text of DOI:10.1016/j.jorganchem.2008.09.075

Journal of Organometallic Chemistry 694 (2009) 316–322
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Spectroscopic and structural characterization of O,O0-(diphenylphosphineoxide)-
amidate and acetylacetonate complexes of pentacoordinate nickel(II)
a
a
a
Rocío García-Bueno a, M. Dolores Santana a, , Gregorio Sánchez , Joaquín García , Gabriel García ,
*
José Pérez b, Luís García b
a Departamento de Química Inorgánica, Universidad de Murcia, 30071 Murcia, Spain
b Departamento de Ingeniería Minera, Geológica y Cartográfica, Área de Química Inorgánica, Universidad Politécnica de Cartagena, E-30203 Cartagena, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 4 July 2008
Received in revised form 11 September
2008
Accepted 19 September 2008
Available online 6 November 2008
Heteroleptic nickel pentacoordinate complexes with the macrocyclic ligands 2,4,4-trimethyl-1,5,9-triaza-
cyclododec-1-ene (Me3-mcN3) or its 9-methyl derivative (Me4-mcN3), as ancillary ligands, and
ꢀ
O,O0-(diphenylphosphineoxide)amidate ligands, [RC(O)NP(O)Ph2] (R = C6H6 (1), C5H4N (2), C4H3S (3)),
have been prepared as well as related acetylacetonate derivatives. The complexes have been studied
by spectroscopic methods (IR, UV–Vis and 1H NMR). In acetone solution, the complexes exhibit
isotropically shifted 1H NMR resonances. The full assignment of these resonances has been achieved
using one- and two-dimensional 1H NMR techniques. The single-crystal structures of {(Me4-
mcN3)Ni[OP(Ph2)NC(Tf)O]}[PF6] (9) and {(Me3-mcN3)Ni(acac)}[PF6] (10) have been established by
X-ray diffraction.
Keywords:
Nickel
Macrocyclic ligands
O,O ligands
Ó 2008 Elsevier B.V. All rights reserved.
NMR spectroscopy
X-ray diffraction
1. Introduction
The incorporation of additional donor substitutes in the ligand
frame allows generating a novel self-complementary system for
The chemistry of metal phosphonates, [RPO3M], has been a
well-investigated area since the 1970s because of application of
these compounds in ion-exchange, catalysis, chemical-sensing,
and electrooptic processes [1]. The structure and properties of
these hybrid materials, which integrate organic and inorganic
characteristics within a single extended framework, can often be
modified by incorporation of additional functions such as hydroxyl,
amino, carboxylate, and pyridyl in the R group [2]. Thus, the syn-
thesis and characterization of phosphoramidate ligands has been
recently developed due to their biological activity [3] and their
coordination chemistry [4]. Some of them with RCðOÞNðHÞPðOÞR20
formula were used as O,O0-donor ligands for metal ions [5]. Ligands
with donor oxygen atoms in 1,3-positions are normally found to be
good chelating groups for the trivalent lanthanide and actinide
ions. Ligands with two P@O or P@O and C@O groups in 1,3-posi-
tions have been found to form many coordination complexes
which display useful extraction applications [6,7]. In order to de-
sign improved extractants, it is helpful to understand the molecu-
lar structure-function characteristics of multifunctional ligands [8].
the needs of supramolecular synthesis [9]. Although crystal struc-
tures of several phosphoramidate and their complexes are already
known [4,10], there are little discussions about the substituents ef-
fects on the structural and NMR parameters and the nickel(II) com-
plexes are scarce [9]. Herein, we present the synthesis of some
phosphoramides with general formula RC(O)N(H)P(O)Ph2,
R = C6H6 (1), C5H4N (2), C4H3S (3), the preparation of the first het-
eroleptic nickel pentacoordinated complexes with O,O0-(diphenyl-
phosphineoxide)amidate ligands, and the related acetylacetonate
derivatives, together with the macrocyclic ligands 2,4,4-tri-
methyl-1,5,9-triazacyclododec-1-ene or its 9-methyl derivative,
as ancillary ligands, in continuation of our work on reactivity stud-
ies of hydroxo nickel complexes [11]. Furthermore, we discussed
on structural, NMR and other spectroscopic (IR, UV–Vis) parame-
ters in these compounds. 1H NMR spectroscopy has become an
excellent technique to study structural and magnetic properties
of paramagnetic metal ions in both coordination complexes and
biological systems [12–14] and a wealth of structural and magnetic
information can be obtained on the local environment of the para-
magnetic metal center. However, a scarcely explored issue is the
determination of the structural and magnetic properties of mono-
nuclear and binuclear nickel(II) ions in both biological and model
systems using 1H NMR spectroscopy [15].
* Corresponding author. Tel.: +34 968 367458; fax: +34 968 364148.
E-mail address: dsl@um.es (M.D. Santana).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.09.075

R. García-Bueno et al. / Journal of Organometallic Chemistry 694 (2009) 316–322
317
2.3. Synthesis of the O,O0-(diphenylphosphineoxide)amidate complexes
2. Experimental
(4ꢀ6)
2.1. General methods
In separate experiments, the corresponding N-(diphenylphos-
phineoxide)amide (0.232 mmol) was added to
a solution of
C, H, and N analyses were carried out with a microanalyzer
Carlo Erba model EA 1108. Infrared spectra were recorded on a
Perkin–Elmer 16F PC FT-IR spectrophotometer using Nujol mulls
between polyethylene sheets. The 1H and 31P NMR spectra were
recorded on a Bruker (AC 200E or AC 300E) spectrometer. Chem-
ical shifts (in ppm) were reported with respect to the residual sol-
vent signal or H3PO4 as standard. The 1H COSY spectra were
obtained at 20 °C for 5 and 6 with 512 data points in the F1
dimension and 1024 data points in the F2 dimension with a delay
time of 150 and 50 ms for 5 and 6, respectively. An unshifted
sine-bell-squared weighting function was applied prior to Fourier
transformation followed by baseline correction in both dimen-
sions and symmetrization. Fast atom bombardment (FAB) mass
spectra were run on a Fisons VG Autospec spectrometer operating
in the FAB+ mode. All chemicals were purchased from Aldrich and
were used without further purification. Solvents were dried and
distilled by general methods before use. The complexes
[Ni(Me3-mcN3)( -OH)]2(PF6)2 (100 mg, 0.116 mmol) in acetone
l
(40 mL) and the mixture was stirred at room temperature for 4 h.
The solvent was removed under reduced pressure to approxi-
mately 10 mL. Addition of diethyl ether (20 mL) resulted in the
precipitation of the expected solid which was filtered off, washed
with diethyl ether and air-dried.
{(Me3-mcN3)Ni[OP(Ph2)NC(Ph)O]}[PF6] (4): Yield: 70.8 mg, 73%.
Anal. Calc. for C31H40N4O2NiP2F6: C, 50.6; H, 5.4; N, 7.6. Found: C,
50.3; H, 5.3; N, 7.9%. KM: 153.7 S cm2 molꢀ1. FAB: m/z 486.4
[M]+. UV–Vis in acetone: k (nm), (
(117.8). IR
NMR ((CD3)2CO, ppm): d 362.0 (H ), 335.1 (2H ), 235.6 (H ),
e
, Mꢀ1 cmꢀ1): 633 (40.4), 386
m
max(cmꢀ1): 3268, 1657, 1590, 1190, 1130, 1044. 1H
a
a
a
199.6 (H ), 87.1 (H ), 42.3 (4-Me, 3H), 37.0 (H ), 28.7 (H ), 21.7
a
a
a
a
(4-Me, 3H), 11.4 (O-C-Ph, 2H), 9.9 (O-C-Ph + O-P-Ph2, 9H), 7.6 (O-
P-Ph2, 4H), ꢀ10.0 (Hb), ꢀ13.4 (2Hb), ꢀ17.4 (2-Me, 3H), ꢀ28.0
(Hb), ꢀ34.0 (Hb),ꢀ35.6 (Hb).
{(Me3-mcN3)Ni[OP(Ph2)NC(3-py)O]}[PF6] (5): Yield: 74.8 mg,
82%. Anal. Calc. for C30H39N5O2NiP2F6: C, 48.9; H, 5.3; N, 9.5.
Found: C, 48.6; H, 5.4; N, 9.3%. KM: 120.6 S cm2 molꢀ1. FAB:
[Ni(mcN3)(l-OH)]2(PF6)2 (mcN3 = 2,4,4-trimethyl-1,5,9-triazacycl-
ododec-1-ene (Me3-mcN3) and its 9-methyl derivative (Me4-
mcN3)) were prepared by procedures previously described
[16,17].
m/z 590.0 [M]+. UV–Vis in acetone: k (nm), ( , Mꢀ1 cmꢀ1): 610
e
(43.7), 379 (120.4). IR
m
max(cmꢀ1): 3274, 1660, 1607, 1587, 1536,
1133, 1089, 1052. 1H NMR ((CD3)2CO, ppm): d 366.4 (H ), 344.3
2.2. Ligands preparation (1ꢀ3)
a
(2H ), 239.0 (H ), 205.7 (H ), 93.2 (H ), 52.4 (4-Me, 3H), 35.0
a
a
a
a
(H ), 30.8 (H ), 21.4 (4-Me, 3H), 13.7 (PyC[6]H), 12.9 (PyC[5]H),
The ligands N-(diphenylphosphineoxide)amide were synthesized
by the following experimental procedure [18]: in separate experi-
ments, chlorodiphenylphosphine (5 mL, 27.9 mmol) was added to
a solution of the corresponding amide (26 mmol): benzamide
(PhC(O)NH2) (1), nicotinamide (3-PyC(O)NH2) (2) or 2-thiophene-
carboxamide (3), triethylamine (3.9 mL, 28 mmol) and DMAP
(240 mg, 20 mmol) in THF (100 mL). A drop of aqueous H2O2
(30% w/w) was added and this solution was refluxed overnight.
a
a
11.7 (PyC[4]H), 10.7 (PyC[2]H), 9.0 (O-P-Ph2, 2H), 8.5 (O-P-Ph2,
2H), 7.7 (O-P-Ph2, 2H), 7.4 (O-P-Ph2, 2H), 6.4 (O-P-Ph2, 2H), ꢀ9.5
(Hb), ꢀ13.1 (2Hb), ꢀ16.0 (2-Me, 3H), ꢀ28.2 (Hb), ꢀ32.5 (Hb),
ꢀ33.9 (Hb).
{(Me3-mcN3)Ni[OP(Ph2)NC(Tf)O]}[PF6] (6 ): Yield: 72.2 mg, 79%.
Anal. Calc. for C29H38N4O2SNiP2F6: C, 47.0; H, 5.1; N, 7.6; S, 4.3.
Found: C, 46.9; H, 5.9; N, 7.5; S, 4.2%. KM: 158.1 S cm2 molꢀ1
.
FAB: m/z 595.6 [M]+. UV–Vis in acetone: k (nm), ( , Mꢀ1 cmꢀ1):
e
The reaction mixture was filtered to remove
a white solid
612 (51.8), 378 (135.6). IR m
max(cmꢀ1): 3271, 1658, 1529, 1513,
(Et3NHCl) and washed with THF (50 mL). The solvent was removed
in vacuo leaving a pale yellow solid. This solid was recrystallised
1130, 1089, 1034. 1H NMR ((CD3)2CO, ppm): d 359.1 (H ), 340.4
a
(2H ), 237.3 (H ), 202.0 (H ), 92.6 (H ), 50.5 (4-Me, 3H), 35.2
by cooling
overnight.
a
concentrated dichloromethane/ether solution
a
a
a
a
(H ), 31.5 (H ), 21.5 (4-Me, 3H), 13.8 (TfC[3]H), 11.0 (TfC[4]H),
a
a
10.2 (TfC[5]H), 8.7 (O-P-Ph2, 2H), 8.4 (O-P-Ph2, 2H), 7.9 (O-P-Ph2,
2H), 7.2 (O-P-Ph2, 2H), 6.6 (O-P-Ph2, 2H), ꢀ9.7 (Hb), ꢀ13.0 (2Hb),
ꢀ15.8 (2-Me, 3H), ꢀ27.8 (Hb), ꢀ31.8 (Hb), ꢀ33.1 (Hb).
N-(diphenylphosphineoxide)phenylamide (1): Yield: 53%. M.p. =
157 °C. Anal. Calc. for C19H16NO2P: C, 71.0; H, 5.0; N, 4.4. Found:
C, 71.2; H, 5.1; N, 4.4%. FAB: m/z 322.2 [M]+, 219.1 [P(OH)Ph2NH2]+.
IR
m
max(cmꢀ1): 3309, 1666, 1590, 1499, 1198, 1128,1108, 1072,
2.4. Synthesis of the O,O0-(diphenylphosphineoxide)amidate complexes
(7–9)
876, 524. 1H NMR (CDCl3, ppm): d 9.12 (d,1H, NH, 2JPNH = 4.83 Hz),
8.02 (d, 2H, Ph), 7.94–7.87 (m, 3H, Ph), 7.58–7.38 (m, 10H, PPh2).
31P{1H} NMR (CDCl3, ppm): d 28.5 (s).
The experimental procedure was similar to that described
above using [Ni(Me4-mcN3)(l-OH)]2(PF6)2 (100 mg, 0.112 mmol)
and the corresponding N-(diphenylphosphino)amide oxide
(0.224 mmol) in acetone (40 mL).
N-(diphenylphosphineoxide)nicotinamide (2): Yield: 59%. M.p. =
188 °C. Anal. Calc. for C18H15N2O2P: C, 67.1; H, 4.7; N, 8.7. Found:
C, 67.0; H, 4.6; N, 8.6%. FAB: m/z 323.2 [M]+, 219.1 [P(OH)Ph2NH2]+.
IR
m
max(cmꢀ1): 3372, 1654, 1588, 1410, 1270, 1186, 1125, 1097,
1023, 530. 1H NMR (CDCl3, ppm):
d
9.31 (d, 1H, NH,
{(Me4-mcN3)Ni[OP(Ph2)NC(Ph)O]}[PF6] (7): Yield: 68.5 mg, 74%.
Anal. Calc. for C32H42N4O2NiPF6: C, 51.3; H, 5.6; N, 7.5. Found: C,
50.9; H, 5.6; N, 7.6%. KM: 150.7 S cm2 molꢀ1. FAB: m/z 500.7
2JPNH = 4.68 Hz), 8.71 (d, 1H, PyC[6]H), 8.44 (d, 1H, PyC[2]H), 7.89
(m, 4H, OPPh2), 7.59–7.54 (m, 1H, PyC[5]H), 7.54–7.42 (m, 6H,
OPPh2), 7.30 (m, 1H, PyC[4]H). 31P{1H} NMR (CDCl3, ppm): d 29.8
(s).
[M]+. UV–Vis in acetone: k (nm), ( , Mꢀ1 cmꢀ1): 648 (44.4), 392
e
(118.4). IR
m
max(cmꢀ1): 3265, 1656, 1592, 1578, 1193, 1129,
1096, 1040. 1H NMR ((CD3)2CO, ppm): d 294.3 (H ), 272.1 (H ),
N-(diphenylphosphineoxide)-2-thiophenecarboxamide (3): Yield:
64%. M.p. = 219 °C. Anal. Calc. for C17H14NO2SP: C, 62.4; H, 4.3; N,
4.3; S, 9.8. Found: C, 62.1; H, 4.2; N, 4.2; S, 9.6%. FAB: m/z 328.1
a
a
256.3 (H ), 195.0 (H ), 183.3 (H ), 118.6 (9-Me, 3H), 85.0 (H ),
a
a
a
a
48.3 (4-Me, 3H), 36.6 (H ), 34.5 (H ), 22.7 (4-Me, 3H), 12.7 (O-C-
a
a
[M]+, 219.1 [P(OH)Ph2NH2]+. IR
m
max(cmꢀ1): 3295, 1657, 1589,
Ph, 2H), 10.5 (O-C-Ph, 2H), 10.1 (O-C-Ph), 9.1 (O-P-Ph2, 4H), 8.6
(O-P-Ph2, 4H), 7.2 (O-P-Ph2,2H), ꢀ9.8 (Hb), ꢀ11.8 (Hb), ꢀ12.9
(Hb), ꢀ17.6 (2-Me, 3H), ꢀ27.6 (Hb), ꢀ33.8 (Hb), ꢀ34.9 (Hb).
{(Me4-mcN3)Ni[OP(Ph2)NC(3-py)O]}[PF6] (8): Yield: 72.2 mg, 83%.
Anal. Calc. for C31H41N5O2NiP2F6: C, 49.6; H, 5.5; N, 9.3. Found: C,
1524, 1202, 1090, 1036, 528–519. 1H NMR (CDCl3, ppm): d 9.83
(1H, NH), 8.10 (d, 1H, TfC[3]H), 7.88 (m, 4H, PPh2), 7.54–7.44 (m,
6H+1H, PPh2, TfC[5]H), 7.00 (m, 1H, TfC[4]H). 31P{1H} NMR (CDCl3,
ppm): d 29.5 (s).

318
R. García-Bueno et al. / Journal of Organometallic Chemistry 694 (2009) 316–322
49.5; H, 5.6; N, 9.0%. KM: 162.8 S cm2 molꢀ1. FAB: m/z 604.7 [M]+.
UV–Vis in acetone: k (nm), (
, Mꢀ1 cmꢀ1): 622 (50.8), 381 (139.4).
IR
max(cmꢀ1): 3266, 1656, 1585, 1523, 1133, 1084, 1067. 1H NMR
((CD3)2CO, ppm): d 294.3 (H ), 276.4 (H ), 262.8 (H ), 193.1 (2H ),
Table 1
Crystal data and structure refinement for 9 and 10.
e
m
Complex
9
10
a
a
a
a
Empirical formula
Formula weight
Temperature (K)
k
Crystal system
Space group
Unit cell dimensions
a (Å)
C34H5oF6N4Ni03P2S
829.49
100(2)
0.71073 A
Monoclinic
P21/n
C17H35F6N3NiO2P
517.16
173(2)
0.71073 A
Monoclinic
P21/c
116.6 (9-Me, 3H), 84.8 (H ), 55.5 (4-Me, 3H), 36.0 (2H ), 22.1 (4-
a
a
Me, 3H), 12.9 (PyC[6]H + PyC[5]H), 11.2 (PyC[4]H), 9.7 (PyC[2]H),
9.6 (O-P-Ph2, 2H), 9.0 (O-P-Ph2, 2H), 7.7 (O-P-Ph2, 2H), 7.5 (O-P-
Ph2, 2H), 6.4 (O-P-Ph2, 2H), ꢀ9.0 (Hb), ꢀ9.9 (Hb), ꢀ12.9 (Hb),
ꢀ16.8 (2-Me, 3H), ꢀ27.4 (Hb), ꢀ33.2 (Hb), ꢀ34.5 (Hb).
{(Me4-mcN3)Ni[OP(Ph2)NC(Tf)O]}[PF6] (9): Yield: 69.7 mg, 70%.
Anal. Calc. for C30H40N4O2SNiP2F6: C, 47.7; H, 5.3; N, 7.4; S, 4.2.
8.6550(3)
23.2308(9)
18.8819(7)
90
91.6350(10)
90
3794.9(2)
4
1.452
10.3168(6)
13.1119(8)
16.4372(10)
90
95.62
90
2212.8(2)
4
1.552
1.018
1084
b (Å)
c (Å)
Found: C, 47.9; H, 5.4; N, 7.5; S, 4.0%. KM: 155.6 S cm2 molꢀ1
.
a
(°)
FAB: m/z 609.6 [M]+. UV–Vis in acetone: k (nm), (
623 (62.1), 379 (166). IR
max(cmꢀ1): 3260, 1657, 1533, 1508,
1131, 1091, 1066. 1H NMR ((CD3)2CO, ppm): d 293.4 (H ), 276.6
e
, Mꢀ1 cmꢀ1):
b (°)
m
c
(°)
V (Å3)
a
Z
(H ), 263.9 (H ), 191.8 (2H ), 116.5 (9-Me, 3H), 85.2 (H ), 53.1
a
a
a
a
Dcalcd. (mg mꢀ3
)
(4-Me, 3H), 36.0 (2H ), 22.2 (4-Me, 3H), 13.7 (TfC[3]H), 10.8
Absorption coefficient (mmꢀ1
F(000)
)
0.720
1736
a
(TfC[4]H), 9.1 (TfC[5]H), 8.8 (O-P-Ph2, 4H), 7.9 (O-P-Ph2, 4H), 7.2
(O-P-Ph2), 6.6 (O-P-Ph2), ꢀ9.5 (2Hb), ꢀ13.1 (Hb), ꢀ16.8 (2-Me,
3H), ꢀ27.2 (Hb), ꢀ33.0 (Hb), ꢀ34.3 (Hb).
Crystal size (mm3)
h range for data collection (°)
Index ranges
0.29 ꢁ 0.11 ꢁ 0.06
1.39–28.26
ꢀ11 6 h 6 10,
ꢀ29 6 k 6 29,
ꢀ24 6 1 6 25
43633
0.28 ꢁ 0.24 ꢁ 0.18
3.03–25.00
ꢀ12 6 h 6 3,0 6 k 6 15,
ꢀ19 6 l 6 19
2.5. Synthesis of the acetylacetonate complexes (10, 11)
Reflections collected
5059
Independent reflections [R(int)
Absorption correction
Refinement method
]
8822 (0.0601)
None
Full-matrix least-
squares on F2
8822/1/462
1.021
R1 = 0.0672,
wR2 = 0.1492
R1 = 0.0918,
wR2 = 0.1661
0.957 and ꢀ0.707
3885 (0.0302)
0.8380 and 0.7637
Full-matrix least-
squares on F2
3885/0/271
0.973
2,4-Pentanodione (0.232 mmol) was added to a solution of
[Ni(mcN3)(l-OH)]2(PF6)2 (0.116 mmol) in acetone (40 mL) and
the mixture was stirred at room temperature for 4 h. The solvent
was removed under reduced pressure to approximately 10 mL.
Addition of diethyl ether (20 mL) resulted in the precipitation of
blue solids which were filtered off, washed with diethyl ether
and air-dried.
Data/restraints/parameters
Goodness-of-fit (GOF) on F2
Final R indices [I > 2
r
(I)]
R1 = 0.0517,
wR2 = 0.1363
R indices (all data)
R1 = 0.0758,
{(Me3-mcN3)Ni(acac)}[PF6] (10): Yield: 76%. Anal. Calc. for
C17H32N3O2NiPF6: C, 39.5; H, 6.8; N, 8.1. Found: C, 39.8; H, 6.6;
N, 8.2%. KM: 159.1 S cm2 molꢀ1. FAB: m/z 368.0 [M]+. UV–Vis in
wR2 = 0.1461
0.665 and ꢀ0.810
Largest difference peak and
hole (e Åꢀ3
)
acetone: k (nm), (
e m
, Mꢀ1 cmꢀ1): 579 (90.4). IR max(cmꢀ1): 3272,
1660, 1594, 1530. 1H NMR ((CD3)2CO, ppm): d 353.9 (H ), 347.3
a
(H ), 225.6 (H ), 191.5 (H ), 93.4 (H ), 49.0 (4-Me, 3H), 34.9
a
a
a
a
(H ), 31.3 (H ), 27.5 (H ), 21.4 (4-Me, 3H), 2.8 (OC-Me, 6H),
3. Results and discussions
3.1. Syntheses and spectroscopic characterization
a
a
a
ꢀ10.4 (2Hb), ꢀ13.2 (Hb), ꢀ16.8 (2-Me, 3H), ꢀ27.0 (–CH–), ꢀ27.5
(Hb), ꢀ32.1 (Hb), ꢀ33.2 (Hb).
{(Me4-mcN3)Ni(acac)}[PF6] (11): Yield: 70%. Anal. Calc. for
C18H34N3O2NiPF6: C, 40.9; H, 6.5; N, 7.9. Found: C, 40.8; H, 6.6;
N, 8.0%. KM: 156.3 S cm2 molꢀ1. FAB: m/z 382.0 [M]+. UV–Vis in
The N-(diphenylphosphineoxide)amides were synthesized by
treating chlorodiphenylphosphine with the corresponding amide
(R-C(O)NH2) in THF with Et3N and DMAP, a drop of H2O2 was also
added (Scheme 1). These phosphoramides behave as weak acids
acetone:
max(cmꢀ1): 3262, 1660, 1590, 1520. 1H NMR ((CD3)2CO, ppm): d
341.0 (H ), 284.2 (H ), 249.3 (H ), 181.6 (H ), 108.1 (9-Me, 3H),
k (nm), (e,
Mꢀ1 cmꢀ1): 589 (93.2), 357 (470.6). IR
m
towards dinuclear hydroxo-complexes. Thus the acid-basic
a
a
a
a
2+
86.7 (H ), 49.7 (4-Me, 3H), 37.2 (H ), 32.4 (H ), 21.6 (4-Me, 3H),
reaction between [Ni(mcN3)(l-OH)]2 and the corresponding N-
a
a
a
10.8 (H ), 1.3 (OC-Me, 6H), ꢀ7.3 (2Hb), ꢀ9.9 (Hb), ꢀ13.1 (Hb),
(diphenylphosphineoxide)amide or 2,4-pentanodione leads to the
formation of the new O,O0-(diphenylphosphineoxide)amidate com-
plexes (4–9) or acetylacetonate complexes (10–11). In these Ni(II)
complexes the organic ligands are coordinated bidentately via oxy-
gen atoms of phosphoryl and carbonyl groups forming six-mem-
bered chelates. The isolated nickel(II) compounds (4–11) are
presented in Scheme 2. All of them are air-stable solids and their
acetone solutions exhibit conductance values corresponding to
1:1 electrolytes [22], which are in good agreement with the pro-
posed formulae. They have been characterized by partial elemental
analyses, FAB+ mass spectrometry and spectroscopic (IR, UV–Vis
and 1H NMR) methods.
a
ꢀ17.1 (2-Me, 3H), ꢀ26.5 (–CH–), ꢀ27.9 (Hb), ꢀ33.7 (Hb), ꢀ34.3
(Hb).
2.6. Crystal structure determination of {(Me4-mcN3)Ni[OP(Ph2)-
NC(Tf)O]}[PF6] (9) and {(Me3-mcN3)Ni(acac)}[PF6] (10)
Crystals suitable for a diffraction study were prepared by a slow
diffusion of diethyl ether into their acetone solutions. Crystallo-
graphic data are summarized in Table 1. Data collection for 10
was performed on a Siemens P4 diffractometer at ꢀ100 °C. Data
collection for 9 was performed at ꢀ173 °C on a Bruker Smart
CCD diffractometer, the diffraction frames were integrated using
the SAINT package [19] and corrected for absorption with SADABS
[20]. The structures were solved by direct methods [21] and re-
fined by full-matrix least-squares techniques using anisotropic
thermal parameters for non-H atoms. Hydrogen atoms were intro-
duced in calculated positions and refined during the last stages of
the refinement.
The IR spectra of derivatives 4–11 show bands in the range
3275–3260 cmꢀ1 assigned to
m
(NH) and a sharp band at 1660–
1655 cmꢀ1 assigned to
m(C@N). Both of them are bands of the coor-
dinated macrocycle Me3-mcN3 or Me4-mcN3 [23]. The IR spectra of
the Ni(II) derivatives 4–9 show bands attributed to the O,O0-(diphe-
nylphosphineoxide)amidate ligands:
m ,
(C–O) 1595–1510 cmꢀ1
m
(P–O) 1195–1125 cmꢀ1 and (N–P) 1090–1030 cmꢀ1 [18]. This
m

R. García-Bueno et al. / Journal of Organometallic Chemistry 694 (2009) 316–322
319
O
C
O
P
O
O
C
(CH3CH2)3N
H2O2 (33v/v)
Ph
PPh2
C
R
N
H
DMAP, PPh2Cl
THF
R
R
N
H
NH2
Ph
R= C6H5 [1]
C5H4N [2]
C4H3S [3]
Scheme 1. Ligands preparation.
Ph
N
O
C
O
P
R´
Me
Me
H
Ph
Me
Me
Me
O
O
O
P
C
Ph/ acetone
Ph
+2 R
N
H
Me
2
N
H
Ni
Ni
Ni
N
N
H
N
N
N
O
H
N
N
H
N
-2 H2O
Me
Me
R
[PF6]
Me
R´
[PF6]2
R´
(Me3-mcN3)
(Me4-mcN3)
H
Me
R´
=
-2 H2O
+ 2 2,4-pentanodione /
acetone
Complex
R
R´
Me
Me
4
5
6
7
8
9
C6H6
H
Me
Me
Me
O
O
C5H4N
C4H3S
C6H6
2
Ni
N
N
H
Me
C5H4N
C4H3S
N
[PF6]
R´
(Me3-mcN3) (10)
(Me4-mcN3) (11)
H
Me
R´=
Scheme 2. Synthesis of the N-(diphenylphosphineoxide)amidate and acetylacetonate complexes of nickel(II).
general pattern of the infrared spectra supports coordination via
oxygen atoms of phosphoryl and carbonyl groups of the deproto-
nated OCNPOꢀ group. Because of the electronic delocalization in
10–11 show in their IR spectra the absorption attributed to the
acetylacetonate ligand
m
(C@O) at ꢂ1590 cmꢀ1. The electronic spec-
tra of 4–11 are quite similar and show two d–d transitions in
the OCNPO fragments is expected to notice
m(N–P) band at
acetone solution with kmax around 630 nm (ꢂ50 Mꢀ1 cmꢀ1
)
frequencies higher than 995 cmꢀ1 [18b]. The Ni(II) derivatives
and 380 nm (ꢂ120 Mꢀ1 cmꢀ1
) which could be assigned to
+
Ph
N
(4)
Me
Ph
(2)
Me
O
O
P
C
Me
Ni
N
N
α
β
H
N
(Tf)
Me
(9)
S
Fig. 1. !H NMR spectra (in d6-acetone solution at r.t.) of 9.

320
R. García-Bueno et al. / Journal of Organometallic Chemistry 694 (2009) 316–322
3B1(F) ? 3E(F) and 3B1(F) ? 3A2, 3E(P) transitions, respectively.
Both kmax values and molar absorptivities are consistent with a
pentacoordinate environment around nickel(II) [24].
based on the considerations used in previous studies of nickel(II)
macrocyclic complexes [11b]. The -methylenic protons shift
downfield whereas the b-methylenic protons shift upfield with re-
gard to the diamagnetic position, probably because of spin polari-
zation mechanisms [26]. Equatorial protons are expected to
experience larger contact shifts than axial protons and therefore
the most downfield resonances are due to a-CHeq and the most up-
field ones to b-CHeq [27]. All the resonances of the phenyl protons
to the N-(diphenylphosphineoxide)amidate ligands are downfield
a
All of the complexes exhibit sharp hyperfine-shifted 1H NMR
signals in acetone solution in the 360 to ꢀ36 ppm chemical shift
range. The 1H NMR data for complexes 4–11 (see Section 2) are
in good agreement with previous results for similar pentacoordi-
nate nickel(II) complexes [25]. A representative proton NMR spec-
trum for complex 9 is shown in Fig. 1. The resonance line pattern
observed for the macrocyclic ligands can be reasonably assigned
to TMS in accordance with a dominant
r-delocalization pattern
of spin density consistent with the nickel(II) ground state [28].
The definitive assignment of these isotropically shifted signals
comes from two-dimensional 1H NMR techniques. The magnitude
COSY spectra of 5 (Fig. 2), recorded at 20 °C, clearly shows cross
signals between resonances at 13.7, 12.9 and 11.7 ppm and also
between resonances at 12.9, 11.7 and 10.7 ppm. These signals
can be assigned to the pyridyl 6-H (13.7), 5-H (12.9), 4-H (11.7)
and 2-H (10.7) protons, respectively, of the O,O0-(diphenylphos-
phineoxide)nicotinamide ligand. The magnitude COSY spectra of
6 (Fig. 3), recorded at 20 °C, shows cross signals between reso-
nances at 13.8 and 11.0 and also between resonances at 13.8,
11.0 and 10.2 ppm. These signals can be assigned to the thiophenyl
3-H (13.8), 4-H (11.0) and 5-H (10.2) protons, respectively, of the
O,O0-(diphenylphosphineoxide)-2-thiophenecarboxamide ligand.
3.2. X-ray diffraction study
The crystal structures of the cation of complexes 9 and 10 are
shown in Figs. 4 and 5. In each crystallized cation, the nickel atom
is five-coordinated, with a square pyramid arrangement of the che-
lating atoms. The structural index parameter
s for pentacoordinate
complexes [29] ( = 0 and 1 for square pyramidal and trigonal
s
bipyramidal structures, respectively) shows values of 0.142 and
0.182 for complexes 9 and 10, respectively (see Table 2).
The three nitrogen atoms of the N3-macrocycle hold the apical
position and two adjacent basal ones, whereas the other two basal
positions correspond to the O,O0-(diphenylphosphineoxide)ami-
date group in 9 and to the acetylacetonate ligand in 10. The basal
plane is formed by N(1), N(2), O(1) and O(2), with a rms deviation
of fitted atoms of 0.0756 and 0.0970 Å, for complexes 9 and 10,
respectively. The Ni atom is 0.3168(15) and 0.2714(14) Å above
of the corresponding basal plane towards the apical N(3) atom
Fig. 2. Magnitude 1H COSY spectrum of complex 5 at 200 MHz at 20 °C in d6-
acetone solution recorded with a delay time of 150 ms. Only the region relevant to
the assignment of pyridyl resonances is shown in the top trace.
Fig. 4. ORTEP drawing of complex
9 showing the atom numbering scheme.
Fig. 3. Magnitude 1H COSY spectrum of complex
d6-acetone solution recorded with a delay time of 50 ms. Only the region relevant to
the assignment of thiophenyl resonances is shown in the top trace.
6
at 200 MHz at 20 °C in
Displacement ellipsoids are drawn at the 50% probability level. The thien-2-yl
fragment is disordered over two positions with occupation factors of 0.67 and 0.33.
For clarity hydrogen atoms are omitted.

R. García-Bueno et al. / Journal of Organometallic Chemistry 694 (2009) 316–322
321
Table 3
Torsion angles of six-membered rings.
9
10
Six-membered rings
NilNl C1 C2 C3 N2
Conformation Deformation Conformation Deformation
0.8136 HC
0.1853 E
0.0011 SB
1.0000 C
8°
0.8014 HC
0.1893 E
0.0093 SB
1.0000 C
0.7479 E
0.2521 HC
–
7°
NilNl C9 C8 C7 N3
8°
10°
9°
14°
0.9517 E
NilN2 C4 C5 C6 N3
Ni1 O1 P1N4C14O2
0.0483 HC
0.9998 SB
0.0002 HC
0.9890 SB
0.0103 HC
0.0007 E
–
Ni1 O1 C13C14C15O2
for complexes 9 and 10, respectively. The plane of the chelate moi-
ety defined by O1, P1, N4, C14 and O2 (rms 0.035) is inclined by
21.93(15)° to the basal plane in complex 9. This complex is the first
pentacoordinate O,O0-(diphenylphosphineoxide)amidate-nickel(II)
derivative showing chelating fashion. In complex 10, the plane of
the chelate moiety defined by O1, C13, C14, C15 and O2 (rmsd
0.0056) is inclined by 17.58(18)° to the basal plane N1, N2, O1
and O2. The macrocycle shows the same configuration in both
complexes. The six-membered rings involving N1 and N3 shows
a chair conformation (C) when is evaluated by the classification
Fig. 5. ORTEP drawing of complex 10 showing the atom numbering scheme.
Displacement ellipsoids are drawn at the 50% probability level. For clarity hydrogen
atoms are omitted.
Table 2
method for
r = 10 [30] (Fig. 6). In both complexes the ring involv-
Selected bond lengths (A) and angles (°) for 9 and 10.
ing N2 and N3 shows a distorted conformation, the closest ideal
conformation is the envelope (E) with a mean deviation from the
ideal torsion angles in the envelope conformation of 10° and 14°
for 9 and 10, respectively (Table 3).
9
10
Ni(1)–O(1)
Ni(1)–O(2)
Ni(1)–N(1)
2.042(2)
2.032(3)
2.047(3)
2.019(3)
1.984(3)
2.044(4)
Ni(1)–N(2)
Ni(1)–N(3)
2.038(3)
2.067(3)
2.040(3)
2.046(4)
Acknowledgements
O(2)–Ni(1)–N(2)
N(2)–Ni(1)–O(1)
N(2)–Ni(1)–N(1)
O(2)–Ni(1)–N(3)
O(1)–Ni(1)–N(3)
O(2)–Ni(1)–O(1)
O(2)–Ni(1)–N(1)
O(1)–Ni(1)–N(1)
N(2)–Ni(1)–N(3)
N(1)–Ni(1)–N(3)
157.73(12)
85.47(11)
89.95(13)
100.63(12)
99.83(11)
90.85(10)
88.51(12)
166.30(12)
101.63(12)
93.74(12)
158.79(13)
85.56(13)
89.68(14)
100.37(13)
96.68(14)
90.29(12)
90.88(13)
169.72(13)
100.77(14)
93.15(15)
We thank Ministerio de Ciencia e Innovación, Spain, (project
CTQ2008-02767/BQU) for financial support. R.G.B. thanks Univers-
idad de Murcia for a grant.
Appendix A. Supplementary material
CCDC 693531 and 693532 contain the supplementary crystallo-
graphic data for 9 and 10. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via www.ccdc.
cam.ac.uk/data_request/cif. Supplementary data associated with
this article can be found, in the online version, at doi:10.1016/
j.jorganchem.2008.09.075.
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