Coordination mode of the nickel(II) cation with N-diisopropoxyphosphinyl-p- bromothiobenzamide

Article abstract of DOI:10.1002/zaac.200700502

Reaction of the potassium salt of N-diisopropoxyphosphinyl-p- bromothiobenzamide p-BrC₆H₄C(S)NHP(O)(OiPr)₂ (HL) with Ni(NO₃)₂ in aqueous EtOH leads to complex of formula [Ni(HL-O)₂(L-O,S)₂] (1). The structure of 1 was investigated by single crystal X-ray diffraction analysis, IR, ¹H and ³¹P{¹H} NMR spectroscopy, MALDI and microanalysis. The nickel(II) ion in 1 has a tetragonal-bipyramidal environment, (O ^ax)₂(O^eq)₂(S^eq) ₂, with two neutral ligand molecules coordinated in axial positions through the oxygen atoms of the P=O groups. The equatorial plane of bipyramide is formed by two anionic ligands involving 1,5-O,S-coordination mode. The chelating ligands are bound in trans configuration.

Full text of DOI:10.1002/zaac.200700502

DOI: 10.1002/zaac.200700502
Coordination Mode of the Nickel(II) Cation with N-Diisopropoxyphosphinyl-p-
bromothiobenzamide
Damir A. Safina,c,*, Felix D. Sokolova, Sergey V. Baranova, Łukasz Szyrwielb, Maria G. Babashkinaa,
Elmira R. Shakirovaa, F. Ekkehardt Hahnc, and Henryk Kozlowskib
a Kazan/Russian Federation, A. M. Butlerov Chemistry Institute, Kazan State University
b Wroclaw/Poland, University of Wroclaw
c Münster/Germany, Institut für Anorganische und Analytische Chemie der Westfalen Wilhelms-Universität Münster
Received October 22nd, 2007.
Abstract. Reaction of the potassium salt of N-diisopropoxyphos-
phinyl-p-bromothiobenzamide p-BrC6H4C(S)NHP(O)(OiPr)2 (HL)
with Ni(NO3)2 in aqueous EtOH leads to complex of formula
[Ni(HL-O)2(L-O,S)2] (1). The structure of 1 was investigated by
single crystal X-ray diffraction analysis, IR, 1H and 31P{1H} NMR
spectroscopy, MALDI and microanalysis. The nickel(II) ion in 1
has a tetragonal-bipyramidal environment, (Oax)2(Oeq)2(Seq)2, with
two neutral ligand molecules coordinated in axial positions through
the oxygen atoms of the PϭO groups. The equatorial plane of
bipyramide is formed by two anionic ligands involving 1,5-O,S-
coordination mode. The chelating ligands are bound in trans con-
figuration.
Keywords: Nickel; Amidophosphate; Chelates; Crystal structure
Complexes of NiII with (thio)(seleno)phosphorus ligands
[R1R2P(X)Y]Ϫ, [R1R2P(X)NP(Y)R3R4]Ϫ and [R1R2C(X)NP-
(Y)R3R4]Ϫ (X, Y ϭ O, S, Se) are of incessant interest because of
their diversity in composition of obtained complexes, versatility of
the coordination modes around the central ion and different mag-
netic properties of NiII containing compounds [1Ϫ6]. Overwhelm-
ing majority of these complexes contain the ligands containing two
donor chalcogen atoms simultaneously (X ϭ Y) [4Ϫ6]. Complexes
of the (thio)(seleno)phosphorus ligands, containing different donor
atoms are considerably less understood, especially with “hard” oxy-
gen and “soft” sulfur or selenium atoms [1Ϫ3].
Thus, versatile coordination properties of ligands HZ towards
NiII inspired us to continue earlier investigations. In this
article
N-diisopropoxyphosphinyl-p-bromotniobenzamide
p-
BrC6H4C(S)NHP(O)(OiPr)2 (HL) was used as a ligand. It was
interesting to investigate the influence of the substituent at the thio-
carbonyl fragment on the complexation properties of HL and HZ.
Results and Discussion
The ligand HL was prepared by reaction of p-bromothiobenz-
amide p-BrC6H4C(S)NH2 with diisopropyl chlorophosphate
(iPrO)2P(O)Cl.
Recently, interesting features, concerning the complexation
properties of N-phosphorylthioureas of common formula
RC(S)NHP(O)(OiPr)2 (R
ϭ p-MeOC6H4NH, p-BrC6H4NH,
tBuNH, c-HexNH) (HZ) towards NiII, were found [1, 2]. It was
established that thioureas HZ form 1,3-N,S-chelates with NiII cat-
ion, containing square-planar NiN2S2 complex core [1]. In the case
of R ϭ iPr, complex of Ni(Z-N,S)2 ·2HZ was obtained [2]. Accord-
ing to the X-ray crystal structure analysis, the neutral ligands in
this complex have not interacted directly with the metal ion and
being in the second sphere interacted via hydrogen bonds between
the P(O)NH protons of free ligands and the PϭO oxygen atoms of
coordinated ligand. Application of the same synthetic procedure
using thioureas RC(S)NHP(O)(OiPr)2 with R ϭ Et2N, morpholine-
N-yl did not result in isolation of single products. According to the
IR and 1H NMR spectra a complicated mixture of complex species
were formed and it was difficult to analyze [1].
Complex of HL with the NiII (1) was prepared by the following
procedure: ligand was converted into potassium salt KL, and fol-
lowed by reaction with Ni(NO3)2 in aqueous EtOH in the presence
of KOH (Scheme 1).
The compound obtained is crystalline solid that is soluble in most
polar solvents. Reaction of the salt KL with Ni(NO3)2 in aqueous
EtOH leads only to the formation of complex Ni(HL-O)2(L-O,S)2
(1). It was previously described that the reaction of the nonsubsti-
tuted N-phosphorylated thiobenzamide C6H5C(S)NHP(O)(OiPr)2
(HQ) with ZnII leads to complex Zn(Q-O,S)2 (2), while in the case
of the CdII two different complexes were formed: Cd2(Q-O,S)4 (3)
and Cd(HQ-O)2(Q-O,S)2 (4) [7]. For CoII three types of complexes
were isolated in the reaction with the potassium salt of HQ:
CoII(Q-O,S)2 (5), CoII(HQ-O)2(Q-O,S)2 (6), CoIII(Q-O,S)3 (7) [8].
* Dr. Damir A. Safin
Kremlevskaya str. 18
Kazan, 420008/Russian Federation
Fax: (007)8432543734
Tel: (007)8432315397
E-mail: damir.safin@ksu.ru
The molecular structures of HL and complex 1 were investigated
by IR, 1H, 31P{1H} NMR spectroscopy, MALDI and elemental
analysis. Crystal structure of 1 was established by single crystal
X-ray diffraction analysis.
Z. Anorg. Allg. Chem. 2008, 634, 835Ϫ838
© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
835

D. A. Safin, F. D. Sokolov, S. V. Baranov, Ł. Szyrwiel, M. G. Babashkina, E. R. Shakirova, F. E. Hahn, H. Kozlowski
Ni(HL)2L2 o Ni(HL)L2 ϩ HL o NiL2 ϩ 2HL
The MALDI mass spectrum of HL contains the [M ϩ H]ϩ molecu-
lar ion peak with the highest intensity. There are peaks with the
medium intensities for the molecular ions [M ϩ Na]ϩ and [M ϩ
K]ϩ. The spectrum contains also [2M ϩ Na]ϩ structure dimeric
ion peak; however, its intensity is very low.
The molecular ion peaks of 1 [M ϩ H]ϩ, [M ϩ Na]ϩ and [M ϩ K]ϩ
are unstable under the same measurement conditions. Its MALDI
spectrum contains all ions characteristic for [NiL2] complex core
i.e. [NiL2 ϩ H]ϩ, [NiL2 ϩ Na]ϩ and [NiL2 ϩ K]ϩ.
The MALDI data of 1 show propensity to dimer formation. The
intensity of the [Ni2L3]ϩ peak in the spectrum of complex 1 is close
to 9 %. The peaks corresponding to the dimer species were also
observed in the ES (electrospray) mass spectra of complexes 2؊4
[7].
Scheme 1 Preparation of complex 1 (R ϭ p-BrC6H4)
According to the X-ray data, the molecule of complex 1 in the
crystal is located in a special position at the symmetry centre. The
IR spectrum of HL has shown bands of all characteristic groups.
The PϭO group is observed as an intense band at 1256 cmϪ1. The
band at 1504 cmϪ1 corresponds to the SϭCϪN fragment. The NH
coordination of the NiII atom is tetragonal bipyramidal (D2h
)
(Fig. 1).
group shows an absorption band at 3080 cmϪ1
.
The IR spectrum of complex 1 contains two bands for different
phosphorus groups. Along with the above band corresponding to
L form at 1148 cmϪ1, a strong PϭO band is observed at 1248 cmϪ1
because of the bound neutral HL molecules. Its frequency de-
creased when compared to that of the band of the free ligand by
8 cmϪ1. The absorption band of NH group at 3136 cmϪ1 also sup-
ports the presence of HL molecules in complex 1. The conjugated
SCN group exhibits an intensive band at 1543 cmϪ1 indicating the
presence of the anionic forms L؊, whereas the SϭCϪN fragment
of the neutral ligand HL is practically at the same area and shows
at 1500 cmϪ1
.
The IR spectra of HL and complex 1 contain a very intensive band
at 1008Ϫ1012 cmϪ1 corresponding to POC group.
31P{1H} NMR spectrum of HL contains a narrow singlet signal
at Ϫ5.9 ppm, which is in the region characteristic for neutral N-
phosphorylated thioamides and thioureas [9].
Figure 1 Thermal ellipsoid representation of complex 1 (hydrogen
atoms are omitted for clarity). Ellipsoids are drawn at the 50 %
probability level.
˚
The signals in the 31P{1H} NMR spectrum of complex 1 are absent
because of strong contact or pseudocontact interactions between
the paramagnetic central ion and the phosphorus atoms [4]. These
pseudocontact interactions are practically absent for the protons
where the dipole-dipole interactions dominate.
Selected interatomic distances/A and angles/°: NiϪO(11) 2.029(2),
NiϪO(12) 2.111(2), NiϪS(1) 2.405(8), P(1)ϪN(1) 1.611(2), P(2)ϪN(2)
1.661(2), P(1)ϪO(11) 1.498(2), P(2)ϪO(12) 1.472(2); O(11)ϪNiϪO(11)
180.00(1), O(11)ϪNiϪO(12) 86.77(7), O(11)ϪNiϪS(1) , O(12)ϪNiϪS(1)
92.95(6), P(1)ϪO(11)ϪNi 125.6(2), P(2)ϪO(12)ϪNi 138.7(2)
The 1H NMR spectrum of complex 1 contains a double set of
equal intensity signals for (iPrO)2P(O) and C6H4 protons. For clar-
ity concerning OCH proton signals of complex 1, the spectrum of
1 and HL was run at 2:1 molar ratio. The increase in intensities of
the high-field OCH group signal and the signal for the o-C6H4 and
m-C6H4 at 7.96 and 8.85 ppm, respectively, concerning the neutral
HL form, together with the COSY spectrum of 1, confirms the
assignment made. 1H NMR spectrum of 1 shows also signal at
11.36 ppm, corresponding to the NH group of the phosphorylam-
ide fragment. This indicates the presence of HL molecules in com-
plex 1.
The equatorial positions of the bipyramid are occupied by two N-
phosphoryl-p-bromothiobenzamide anions L؊, bonded through
sulfur and oxygen atoms of thiocarbonyl and phosphoryl groups,
respectively. The six-membered NiϪOϪPϪNϪCϪS cycle has a
half-chair conformation; the OϪPϪNϪCϪS backbone is flat. The
ligands are in trans configuration. Neutral ligand molecules are
coordinated in the axial positions through the oxygen atoms
of the phosphoryl groups. The lengths of the NiϪO bonds in the
˚
chelate rings are 2.027(3) A and the bonds with the axial oxygen
؊
˚
atoms are 2.111(2) A. The phenylene ring of the anionic ligand L
is slightly rotated relative to the plane of the SCN moiety
(torsion angles are N(1)ϪC(1A)ϪC(2A)ϪC(7A) 16.6(3)° and
S(1)ϪC(1A)ϪC(2A)ϪC(3A) 16.8(2)°, while in the neutral ligand
the aromatic ring is considerably rotated relative to the plane of
The signals in the proton spectrum of 1 are broaden because of the
paramagnetic ion presence and possible partial dissociation in the
solution [10]:
836
www.zaac.wiley-vch.de
© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2008, 835Ϫ838

Coordination Mode of the Nickel(II) Cation
the SϭCϪN group (torsion angles N(2)ϪC(1B)ϪC(2B)ϪC(7B)
35.6(2)° and S(2)ϪC(1B)ϪC(2B)ϪC(3B) 33.7(2)°.
ring to the resulting potassium salt. The mixture was stirred at
2Ϫ4 °C for a further 3 h and left overnight at room temperature.
To the obtained suspension deionized water (100 mL) was added.
Water phase was separated and treated with HCl (0.1 N solution)
till reaching pH 4Ϫ5. The resulting product was extracted with
benzene and dried with anhydrous MgSO4. The solvent was then
removed in vacuo. An orange precipitate was isolated from di-
chloromethane by n-hexane. Yield: 0.72 g (63 %). M.p. 134 °C.
C13H19BrNO3PS (380.24): calcd. C 41.06, H 5.04, N 3.68; found:
C 41.13, H 4.97, N 3.76 %.
The character of the intramolecular hydrogen bond in complex 1
differs from the compounds 4 and 6. There are two intramolecular
NH···O bonds between the oxygen atom of the PϭO group of the
anionic ligand L؊ and the hydrogen atom of the NH fragment of
the neutral ligand HL in the crystal of complex 1, while in isostruc-
tural complexes 4 and 6 the intramolecular NH···S bonds are
formed by the sulfur atom of the PϭS group of the anionic ligand
L؊. The hydrogen bond parameters in the molecule are as follows:
1H NMR (CDCl3): δ ϭ 1.35 (d, 3JH,H ϭ 6.1 Hz, 6 H, CH3), 1.39 (d, 3JH,H ϭ
˚
6.1 Hz, 6 H, CH3), 1.64 (d, 3JH,H ϭ 6.3 Hz, 12 H, CH3), 3.80 (s, 6 H, OCH3),
N(2)ϪH(2)···O(11) (Ϫxϩ1, Ϫyϩ1, Ϫzϩ1), d(NϪH) 0.79 A,
3
3
4.81 (d. sept, JH,H
ഠ
3JP,H ϭ 6.2 Hz, 2 H, OCH), 7.51 (d, JH,H ϭ 8.2 Hz,
˚
˚
d(H···O) 2.04 A, d(N···O) 2.808(2) A, Є(NϪH···O) 162°.
2 H, m-H, C6H4), 7.78 (d, 3JH,H ϭ 8.5 Hz, 2 H, o-H, C6H4), 9.01 (br. s, 1 H,
NH). 31P{1H} NMR (CDCl3): δ ϭ Ϫ5.9. IR: νϳ ϭ 1008 (POC), 1256 (Pϭ
O), 1504 (SϭCϪN), 3080 (NH) cmϪ1. MS (MALDI): m/z (%) ϭ 382 (100)
[M ϩ H]ϩ, 404 (31) [M ϩ Na]ϩ, 420 (43) [M ϩ K]ϩ, 785 (4) [2M ϩ Na]ϩ.
In summary, a novel NiII complex has been successfully synthe-
sized. Complex obtained is the first example of NiII with the asym-
metric RC(S)NHP(O)(OiPr)2 ligand. The distinction in kind of the
hydrogen bond formation in a crystal of complex 1, can be conse-
quence of the influence of the substituent steric size (p-BrC6H4 vs.
Ph) on the packing of molecules in a crystal.
Synthesis of Ni(HL)2L2 (1)
A suspension of HL (1.91 g, 5 mmol) in aqueous ethanol (20 mL)
was mixed with an ethanol solution of potassium hydroxide (0.28 g,
5 mmol). An aqueous (20 mL) solution of Ni(NO3)2 ·6H2O (0.81 g,
2.8 mmol) was added dropwise under vigorous stirring to the re-
sulting potassium salt. The mixture was stirred at room tempera-
ture for a further 3 h and left overnight. The resulting complex was
extracted with dichloromethane, washed with water and dried with
anhydrous MgSO4. The solvent was then removed in vacuo. The
residue was recrystallised from a dichloromethane/n-hexane mix-
ture. Complex 1 was obtained as orange crystals. Yield: 1.42 g
(72 %). M.p. 159 °C. C52H74Br4N4NiO12P4S4 (1577.63): calcd. C
39.48, H 4.79, N 3.53; found: C 39.62, H 4.70, N 3.65 %.
Experimental Section
Physical measurements
Infrared spectra (Nujol) were recorded with a Specord M-80 spec-
trometer in the range 400-3600 cmϪ1. NMR spectra were obtained
on a Varian Unity-300 NMR spectrometer at 25 °C. 1H and
31P{1H} spectra were recorded at 299.948 and 75.429 MHz, respec-
tively. Chemical shifts are reported with reference to SiMe4 (1H)
and H3PO4 (31P{1H}). MALDI mass spectra of HL and 1 were
obtained using a Bruker Reflex IV spectrometer, and elemental
analyses were performed on a Vario EL III CHNS elemental ana-
lyzer at the IAAC, University of Münster, Germany. Elemental
analyses were performed on a Perkin-Elmer 2400 CHN microana-
lyser.
1H NMR (CDCl3): δ ϭ 0.76 (br. s, 12 H, CH3, HL), 0.76 (br. s, 12 H, CH3,
HL), 0.94 (br. s, 12 H, CH3, LϪ), 1.79 (br. s, 12 H, CH3, LϪ), 1.87 (br. s,
12 H, CH3, L), 3.73 (br. s, 4 H, OCH, HL), 5.04 (br. s, 4 H, OCH, LϪ), 7.31
(br. s, 4 H, m-H, C6H4, LϪ), 7.96 (br. s, 4 H, m-H, C6H4, HL), 8.85 (br. s,
4 H, o-H, C6H4, HL), 9.06 (br. s, 4 H, o-H, C6H4, LϪ), 11.36 (br. s, 2 H,
NH). 31P{1H} NMR (CDCl3): the signal is absent because of extremely
broadening. IR: νϳ ϭ 1012 (POC), 1148 (PϭO, LϪ), 1248 (PϭO, HL), 1500
(SϭCϪN, HL), 1543 (SCN, LϪ), 3136 (NH) cmϪ1. MS (MALDI): m/z
(%) ϭ 819 (27) [NiL2 ϩ H]ϩ, 841 (63) [NiL2 ϩ Na]ϩ, 857 (100) [NiL2
ϩ
Data collection and refinement for Ni(HL2)L2 (1)
K]ϩ, 1257 (9) [Ni2L3]ϩ.
Crystals of 1 were obtained by slow evaporation of the solvent from
dichloromethane/n-hexane solutions of complex. C52H74Br4N4Ni-
O12P4S4, Mr ϭ 1577.67 g molϪ1, yellow blocks, orthorhombic,
CCDC 661321 contains the supplementary crystallographic
data for 1. These data can be obtained free of charge via
http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; fax: (ϩ44) 1223-336-033; or e-mail
deposit@ccdc.cam.ac.uk.
˚
˚
space group Pbca a ϭ 12.738(3) A, b ϭ 22.288(5) A, c ϭ
3
23.475(6) A, V ϭ 6665(3) A , ρ ϭ 1.572 g cmϪ3, μ(Mo-Kα) ϭ
2.968 mmϪ1. The X-ray intensity data were measured at 100(2) K
on a KM4CCD diffractometer and graphite-monochromatied
Mo-Kα radiation generated by middle-focus X-ray tube operated
at 50 kV and 35 mA. The images were indexed, integrated and
scaled using the KUMA data reduction package. The unit cell par-
ameters were refined. The structure was solved by direct method
using SHELIXX-97 [11] program. Hydrogen atoms were placed in
the calculated positions and were refined using riding model except
H2 witch was located on difference map. The numbering of the
atoms is shown in Fig. 1 (ORTEP) [12].
˚
˚
Acknowledgements. This work was supported by the joint program
of CRDF and the Russian Ministry of Education and Science
(BRHE 2004 Y2-C-07-02); the joint program of DAAD “Michail-
Lomonosov” and the Russian Ministry of Education and Science
(Forschungsstipendien 2006/2007) and partly by University of
Wroclaw.
[1] F. D. Sokolov, S. V. Baranov, D. A. Safin, F. E. Hahn, M.
Kubiak, T. Pape, M. G. Babashkina, N. G. Zabirov, J. Gale-
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I. A. Litvinov, B. I. Khairutdinov, R. A. Cherkasov, Mendeleev
Commun. 2007, 17, 222Ϫ223.
Synthesis of p-BrC6H4C(S)NHP(O)(OiPr)2 (HL)
A suspension of p-bromothiobenzamide (0.65 g, 3 mmol) in anhy-
drous dimethyl sulfoxide (50 mL) and benzene (100 mL) was mixed
with potassium hydroxide (3.36 g, 60 mmol) for 2 h and then co-
oled till 2 °C. A benzene (40 mL) solution of diisopropyl chloro-
phosphate (0.6 g, 3 mmol) was added dropwise under vigorous stir-
Z. Anorg. Allg. Chem. 2008, 835Ϫ838
© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
837

D. A. Safin, F. D. Sokolov, S. V. Baranov, Ł. Szyrwiel, M. G. Babashkina, E. R. Shakirova, F. E. Hahn, H. Kozlowski
ˆ
[3] A. Silvestru, D. Bilc, R. Rösler, J. E. Drake, I. Haiduc, Inorg.
[8] (a) F. D. Sokolov, D. A. Safin, N. G. Zabirov, L. N. Yamalieva,
D. B. Krivolapov, I. A. Litvinov, Mendeleev Commun. 2004,
14, 51Ϫ52. (b) D. A. Safin, P. Mlynarz, F. E. Hahn, M. G.
Babashkina, F. D. Sokolov, N. G. Zabirov, J. Galezowska, H.
Kozlowski, Z. Anorg. Allg. Chem. 2007, 633, 1472Ϫ1479.
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[5] I. Haiduc, J. Organomet. Chem. 2001, 623, 29Ϫ42 and refer-
ences therein.
[6] P. Moore, W. Errington, S. P. Sangha, Helv. Chim. Acta 2005,
88, 782Ϫ795.
[10] The dynamic behavior of complex 1 in solutions will be dis-
cussed and published elsewhere.
[7] F. D. Sokolov, D. A. Safin, N. G. Zabirov, V. V. Brusko, B. I.
Khairutdinov, D. B. Krivolapov, I. A. Litvinov, Eur. J. Inorg.
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[11] G. M. Sheldrick, SHELXS-97, Program for the Solution of
Crystal Structures, University of Göttingen, Germany, 1997.
[12] L. J. Farrugia, J. Appl. Cryst. 1997, 30, 565.
838
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Z. Anorg. Allg. Chem. 2008, 835Ϫ838