Complexes of N-phosphorylated thioureas RNHC(S)NHP(O)(OiPr)2 (R = 2-MeC6H4, 2,6-Me2C6H3, 2,4,6-Me3C6H2) with nickel(II)

Article abstract of DOI:10.1080/10426501003671478

The reaction of O,O′-diisopropylphosphoric acid isothiocyanate (iPrO)2P(O)NCS with 2-methylaniline 2-MeC₆H₄NH ₂, 2,6-dimethylaniline 2,6-Me₂C₆H ₃NH2, or 2,4,6-trimethylaniline 2,4,6-Me

Full text of DOI:10.1080/10426501003671478

Phosphorus, Sulfur, and Silicon, 185:2426–2432, 2010
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426501003671478
COMPLEXES OF N-PHOSPHORYLATED THIOUREAS
RNHC(S)NHP(O)(OiPr)2 (R = 2-MeC6H4, 2,6-Me2C6H3,
2,4,6-Me3C6H2) WITH NICKEL(II)
Damir A. Safin,1 Maria G. Babashkina,1 Michael Bolte,2
and Axel Klein1
1Institut fu¨r Anorganische Chemie, Universita¨t zu Ko¨ln, Ko¨ln, Germany
2Institut fu¨r Anorganische Chemie, J.-W.-Goethe-Universita¨t, Frankfurt/Main,
Germany
The reaction of O,Oꢀ-diisopropylphosphoric acid isothiocyanate (iPrO)2P(O)NCS
with 2-methylaniline 2-MeC6H4NH2, 2,6-dimethylaniline 2,6-Me2C6H3NH2, or
2,4,6-trimethylaniline 2,4,6-Me3C6H2NH2 leads to the N-phosphorylated thioureas
RNHC(S)NHP(O)(OiPr)2 (R
=
2-MeC6H4 , ,
HLI; 2,6-Me2C6H3 HLII; 2,4,6-
Me3C6H2 , HLIII). Reaction of the potassium salts of HLI–III with Ni(II) in aqueous EtOH
leads to [Ni(LI–III-N,S)2] ([NiLI–III2]) chelate complexes. The compounds obtained were
1
investigated by 1H, 31P{ H} NMR spectroscopy and microanalysis. The molecular structure
of the thiourea HLIII was elucidated by single crystal X-ray diffraction analysis. Single
crystal X-ray diffraction studies showed that HLIII forms both intra- and intermolecular
hydrogen bonds, which in turn leads to the formation of polymeric chains. One of the
. . .
intermolecular hydrogen bonds is of the type N
intermolecular C
H
S. Moreover, the formation of
6
. . .
H η -phenyl interactions was established.
Supplemental materials are available for this article. Go to the publisher’s online edition of
Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental
file.
Keywords Crystal structure; hydrogen bond; nickel(II); phosphorylthiourea
INTRODUCTION
There have been a great number of studies of the coordination chemistry of imi-
dodiphosphinates R2P(X)NHP(Y)Rꢁ2 (HZ) (X, Y O, S; R, Rꢁ alkyl, aryl) with various
metal cations.1–17 In particular, the complexation properties of HZ towards Ni(II) are of
great interest due to the coordination versatility: octahedral, tetrahedral, and square-planar.
The overwhelming majority of Ni(II) complexes contain symmetric anionic ligands Z,
Received 25 December 2009; accepted 1 February 2010.
This work was supported by the Russian Science Support Foundation. D.A.S. and M.G.B. thank DAAD for
the scholarships (Forschungsstipendien 2008/2009).
Address correspondence to Damir A. Safin and Axel Klein, Institut fu¨r Anorganische Chemie, Universita¨t
zu Ko¨ln, Greinstrasse 6, D-50939 Ko¨ln, Germany. E-mail: damir.safin@ksu.ru; axel.klein@uni-koeln.de
2426

COMPLEXES OF N-PHOSPHORYLATED THIOUREAS
2427
which contain both identical donor atoms (X
Y) and substituents (R
Rꢁ) simulta-
neously,9–16 although some studies on unsymmetrical HZ ligands have been reported.17
However, these investigations have been devoted to either mixed chalcogens or mixed
substituent complexes. Ni(II) complexes usually contain a square-planar or octahedral
complex core. The tetrahedral environment in Ni(II) complexes with HZ is rare and not
well understood, although some examples have been reported.12–17
Recently, we reported some synthetic results as a preliminary communication.18
In this article, we report the synthesis and characterization of N-phosphorylated
thioureas RNHC(S)NHP(O)(OiPr)2 (R = 2-MeC6H4 , HLI; 2,6-Me2C6H3 , HLII;
2,4,6-Me3C6H2 , HLIII). The reaction of the potassium salts of HLI–III with Ni(II) in
aqueous EtOH leads to [Ni(LI–III-N,S)2] ([NiLI–III2]) chelate complexes.
RESULTS AND DISCUSSION
The compounds HLI–III were synthesized by the treatment of 2-methylaniline,
2,6-dimethylaniline, or 2,4,6-trimethylaniline with the isothiocyanate (iPrO)2P(O)NCS
(Scheme 1). Complexes [NiLI–III2] were prepared by the following procedure: the lig-
and was deprotonated in situ using KOH, followed by reaction with NiCl2 (Scheme 2). The
compounds obtained are crystalline solids, which are soluble in most polar solvents. The
formation of HLI–III by the addition reaction of the NH2 group of the corresponding amine
and (iPrO)2P(O)NCS and the coordination mode of the anionic ligands in [NiLI–III2] were
1
1
investigated by 31P{ H} and H NMR spectroscopy; their compositions were established
by elemental analysis.
(Me)
Me
(Me)
H
N
H
N
OiPr
OiPr
(Me)
NH2 + S
C
N
P
(Me)
OiPr
OiPr
P
O
S
O
Me
HLI-III
Scheme 1
(Me)
H
S
O
P
OiPr
OiPr
(Me)
N
1) KOH
2) 1/2 NiCl2
N
HLI-III
Ni
N
S
Me
Me
iPrO
iPrO
P
N
(Me)
O
H
(Me)
[NiLI-III
]
2
Scheme 2

2428
D. A. SAFIN ET AL.
1
The 31P{ H} NMR spectra of HLI–III each contain a singlet signal at −6.4, −6.3,
and −5.9 ppm, respectively, which is typical for N-phosphoryl thioureas.19 The 1H NMR
spectra of the thioureas contain a set of signals for the iPr protons: a doublet or two doublets
for the CH3 protons at 1.39–1.46 ppm and a doublet of septets for the CH protons in the
area 4.77–4.87 ppm. The Me proton signals were observed at 2.24–2.32 ppm. The aromatic
ring and PNH proton signals are at 6.91–7.61 ppm. Signals for the arylNH protons in the
spectra are at 9.42–10.07 ppm. These signals are in a low-field area because of the hydrogen
. . .
bonds’ formation of the arylN H O = P type.
The Ni(II) atom in the complexes [NiLI–III2] was found in a square-planar N2S2
environment formed by the nitrogen and sulfur atoms of the N P and C S groups. Earlier
studies on the 1,5-S,S’-complexes of the Ni(II) ion with N-thiophosphorylated thiourea
PhNHC(S)NHP(S)(OiPr)2 in CD2Cl2 solution have shown a multicomponent equilibrium
between complex species with a tetrahedral or square-planar coordination geometry around
the tetracoordinated metal ion. In these cases, the product mixture can become even more
complicated due to the formation of the five- and six-coordinated Ni(II) species, which
might exhibit a 1,5-O,S- or 1,3-N,S-type of coordination.
1
In the 31P{ H} spectra of the complexes [NiLI–III2], a singlet signal with a chemical
shift at 2.0–2.6 ppm was observed. The signal is characteristic for the amidophosphate
environment of the phosphorus nuclei.19 These signals are 8.3–8.5 ppm low-field shifted
in comparison to the corresponding resonance of the parent phosphorylated thiourea. It
1
is noteworthy that the 31P{ H} resonance in the spectra of the complexes [NiLI–III2] is
observed in the region characteristic for the 1,3-N,S-chelate complexes of Ni(II) with
RNHC(S)NHP(O)(OiPr)2 ligands.20
The 1H NMR spectra of the complexes [NiLI–III2] contain only signals that correspond
to the proposed structures. The spectra contain a set of signals for the iPr protons: two
doublets for the CH3 protons at 1.30–1.62 ppm and a doublet of septets for the CH protons
at 4.59–4.66 ppm. The signals for the Me protons are observed at 2.21–2.36 ppm. The
aromatic ring proton signals in the spectra of [NiLI–III2] are at 6.91–7.36 ppm. The signal
for the NHP group proton is absent in the 1H NMR spectra of [NiLI–III2]. This confirms the
presence of the ligand anionic form in the structure of complexes. Signals for the arylNH
protons in the spectra of the complexes are at 10.38–10.51. These signals are in a low-field
. . .
area because of the hydrogen bonds’ formation of the arylN H O P type.
Crystals of HLIII were obtained by recrystallization from dichloromethane–n-hexane
solution (Table I). The molecular conformation and geometric parameters are shown in
Figure 1.
The compound HLIII crystallizes in the space group P–1. The asymmetric unit con-
tains two independent molecules. The parameters of the C S, C N, P N, and P O
bonds observed for HLIII (Figure 1) are in the typical range for N-phosphorylated thiourea
derivatives.19 The S C N P backbone in the crystal phase has an E-conformation. The
aryl fragment is almost orthogonal to the N C(S) N P plane. The crystal structure is
ꢁ
. . .
stabilized by intramolecular hydrogen bonds of the types N(2) H(2) O(3)[O(3 )] P(1)
. . .
and N(2A) H(2A) O(3A) P(1A) (Figure 1, see also Table S1, Supplemental Materials,
available online). Two independent molecules form a dimer due to intermolecular hydrogen
ꢁ
. . .
. . .
bonds of the types N(2) H(2) O(3A) P(1A) and N(2A) H(2A) O(3)[O(3 )] P(1)
(Figure 1, Table S1). Yet another mode of aggregation is found for this dimer. Two
independent molecules form interactions between the OCH hydrogen atoms and the
aryl rings of an adjacent molecule (Table S2, Supplemental Materials). Furthermore,
dimers form polymeric chains due to the intermolecular hydrogen bonds of the types

COMPLEXES OF N-PHOSPHORYLATED THIOUREAS
Table I Crystal structure and data refinement parameters for HLIII
2429
Empirical formula
C16H27N2O3PS
358.43
Formula weight (g mol−1
)
Temperature (K)
Crystal system
Space group
a (Å)
173(2)
Triclinic
P–1
10.6334(7)
13.4890(8)
15.7710(10)
82.491(5)
70.663(5)
67.113(5)
1966.4(2)
4
b (Å)
c (Å)
α (◦)
β (◦)
γ (◦)
V (Å3)
Z
Dcalc (Mg m−3
)
1.211
0.260
768
Absorption coefficient, µ (mm−1
F(000)
)
Crystal size (mm)
Recording range, θ (◦)
Number of recorded reflections
0.32 × 0.26 × 0.21
3.55–25.59
21017
Number of recorded independent reflections
Final R indices [I > 2sigma(I)]
R indices (all data)
S
7336 [R(int) = 0.0465]
R1 = 0.0389, wR2 = 0.0937
R1 = 0.0568, wR2 = 0.0989
0.951
Figure 1 Thermal ellipsoid representation of HLIII. Ellipsoids are drawn at the 50% probability level. H-
atoms, not involved in hydrogen bonding, are omitted for clarity. Selected bond distances (Å) and angles (◦):
P(1)–O(3) 1.482(2), P(1)–O(3ꢁ) 1.391(7), P(1)–N(1) 1.656(2), S(1)–C(1) 1.675(2), N(1)–C(1) 1.383(2), N(2)–C(1)
1.333(2), P(1A)–O(3A) 1.4656(14), P(1A)–N(1A) 1.658(2), S(1A)–C(1A) 1.673(2), N(1A)–C(1A) 1.378(2),
N(2A)–C(1A) 1.334(2); O(3)–P(1)–N(1) 113.29(9), O(3ꢁ)–P(1)–N(1) 116.3(4), C(1)–N(1)–P(1) 128.61(14),
N(2)–C(1)–N(1) 117.1(2), N(1)–C(1)–S(1) 119.45(14), N(2)–C(1)–S(1) 123.44(13), O(3A)–P(1A)–N(1A)
113.02(8), C(1A)–N(1A)–P(1A) 128.27(14), N(2A)–C(1A)–N(1A) 116.8(2), N(1A)–C(1A)–S(1A) 120.05(14),
N(2A)–C(1A)–S(1A) 123.11(14).

2430
D. A. SAFIN ET AL.
. . .
. . .
N(1) H(1) S(1A)#1 C(1A)#1 and N(1A) H(1A) S(1)#2 C(1)#2 (Figure 1, Ta-
ble S1).
CONCLUSIONS
In summary, we have demonstrated the syntheses of three new N-phosphorylated
thioureas HLI–III by addition of phosphorylisothiocyanate to the corresponding amine.
Single crystal X-ray diffraction studies showed the thiourea HLIII to form both intra- and
intermolecular hydrogen bonds, which in turn lead to polymeric chain formation. Moreover,
III
6
. . .
according to the X-ray data of HL , the formation of the intermolecular C H η -phenyl
interactions were established.
The data presented allow us to confirm that, at least for the investigated N-
phosphorylthiourea ligands HLI–III, the formation of the intramolecular hydrogen bonds
. . .
N H
O
P is a necessary condition for the 1,3-N,S-isomer stabilization in the square-
planar complexes of Ni(II) [NiLI–III2]. Thus, the intramolecular hydrogen bonding realized
outside the coordination sphere of the metal cation is the reason for the dramatic changes
of such important parameters as bite angle and the ligand’s field strength.
EXPERIMENTAL
Physical Measurements
NMR spectra in CDCl3 were obtained on a Bruker Avance 300 MHz spectrometer
1
1
at 25◦C. H and 31P{ H} NMR spectra were recorded at 299.948 and 121.420 MHz,
respectively. Chemical shifts are reported with reference to SiMe4 (1H) and 85% H3PO4
(31P{ H}). Elemental analyses were performed on a CHNS HEKAtech EuroEA 3000
1
analyzer.
Synthesis of HLI–III
A solution of 2-methylaniline, 2,6-dimethylaniline, or 2,4,6-trimethylaniline (5
mmol; 0.54, 0.61, or 0.68 g) in anhydrous CH2Cl2 (15 mL) was treated under vigor-
ous stirring with a solution of (iPrO)2P(O)NCS (6 mmol, 1.34 g) in the same solvent. The
mixture was stirred for 1 h. The solvent was removed under vacuum, and the product was
purified by recrystallization from a 1:5 (v/v) mixture of dichloromethane and n-hexane.
HLI. Yield: 1.42 g (86%); mp: 72◦C; Anal. Calcd for C14H23N2O3PS (330.38):
1
C, 50.90; H, 7.02; N, 8.48; Found: C, 50.96; H, 6.95; N, 8.52; H NMR δ (ppm): 1.39
3
3
(d, JH,H = 6.1 Hz, 12H, CH3, iPr), 2.31 (s, 3H, CH3, Me), 4.83 (d. sept, JPOCH = 7.1
Hz, 3JH,H = 6.0 Hz, 2H, OCH), 6.94–7.61 (m, overlapped with the solvent signal, C6H4 +
PNH), 9.42 (s, 1H, NH); 31P{ H} NMR δ (ppm): −6.4.
1
HLII. Yield: 1.62 g (94%); mp: 89◦C; Anal. Calcd for C15H25N2O3PS (344.41): C,
52.31; H, 7.32; N, 8.13; Found: C, 52.20; H, 7.37; N, 8.05; 1H NMR δ (ppm): 1.43 (d, 3JH,H
= 6.1 Hz, 6H, CH3, iPr), 1.46 (d, 3JH,H = 6.2 Hz, 6H, CH3, iPr), 2.32 (s, 6H, CH3, Me),
4.87 (d. sept, 3JPOCH = 7.2 Hz, 3JH,H = 6.1 Hz, 2H, OCH), 7.09–7.36 (m, overlapped with
the solvent signal, C6H3 + PNH), 9.59 (s, 1H, NH); 31P{ H} NMR δ (ppm): −6.3.
1
HLIII. Yield: 1.29 g (72%); mp: 97◦C; Anal. Calcd for C16H27N2O3PS (358.44): C,
53.62; H, 7.59; N, 7.82; Found: C, 53.71; H, 7.68; N, 7.89; 1H NMR δ (ppm): 1.42 (d, 3JH,H
= 6.2 Hz, 12H, CH3, iPr), 2.24 (s, 6H, CH3, Me), 2.29 (s, 3H, CH3, Me), 4.77 (d. sept,

COMPLEXES OF N-PHOSPHORYLATED THIOUREAS
2431
3JPOCH = 6.8 Hz, 3JH,H = 6.2 Hz, 2H, OCH), 6.91 (s, 2H, C6H2), 7.02 (br. s, 1H, PNH),
1
10.07 (s, 1H, NH); 31P{ H} NMR δ (ppm): −5.9.
Synthesis of [NiLI–III
]
2
A suspension of HLI–III (3 mmol; 0.99, 1.03, or 1.08 g) in aqueous EtOH (10 mL)
was mixed with an aqueous EtOH solution of potassium hydroxide (3.3 mmol, 0.18 g). An
aqueous EtOH (10 mL) solution of NiCl2 (1.9 mmol, 0.25 g) was added dropwise under
vigorous stirring to the resulting potassium salt. The mixture was stirred at room temper-
ature for a further 3 h and then left overnight. The resulting complex was extracted with
dichloromethane, washed with water, and dried with anhydrous MgSO4. The solvent was
then removed under vacuum. Violet [NiLI–III2] crystals were isolated from dichloromethane
by n-hexane.
[NiLI2]. Yield: 0.89 g (83%); mp: 118◦C; Anal. Calcd for C28H44N4NiO6P2S2
1
(717.44): C, 46.88; H, 6.18; N, 7.81; Found: C, 46.97; H, 6.14; N, 7.85; H NMR δ
(ppm): 1.33 (d, 3JH,H = 6.0 Hz, 12H, CH3, iPr), 1.57 (d, 3JH,H = 6.2 Hz, 12H, CH3, iPr),
2.36 (s, 6H, CH3, Me), 4.62 (d. sept, 3JPOCH = 6.8 Hz, 3JH,H = 6.2 Hz, 4H, OCH), 6.91–7.36
1
(m, overlapped with the solvent signal, C6H4), 10.38 (s, 2H, NH); 31P{ H} NMR δ (ppm):
2.1.
[NiLII ]. Yield: 0.86 g (77%); mp: 91◦C; Anal. Calcd for C30H48N4NiO6P2S2
2
1
(745.49): C, 48.33; H, 6.49; N, 7.52; Found: C, 48.24; H, 6.52; N, 7.46; H NMR δ
3
3
(ppm): 1.36 (d, JH,H = 6.2 Hz, 12H, CH3, iPr), 1.62 (d, JH,H = 6.1 Hz, 12H, CH3,
iPr), 2.34 (s, 12H, CH3, Me), 4.59 (d. sept, 3JPOCH = 7.0 Hz, 3JH,H = 6.2 Hz, 4H, OCH),
7.01–7.32 (m, overlapped with the solvent signal, C6H3), 10.51 (s, 2H, NH); 31P{ H} NMR
1
δ (ppm): 2.0.
[NiLIII2]. Yield: 1.11 g (96%); m. p.: 128◦C; Anal. Calcd for C32H52N4NiO6P2S2
(773.55): C, 49.69; H, 6.78; N, 7.24; Found: C, 49.60; H, 6.83; N, 7.21; 1H NMR δ (ppm):
1.30 (d, 3JH,H = 6.2 Hz, 12H, CH3, iPr), 1.59 (d, 3JH,H = 6.1 Hz, 12H, CH3, iPr), 2.21 (s,
3
3
12H, CH3, Me), 2.32 (s, 6H, CH3, Me), 4.66 (d. sept, JPOCH = 6.5 Hz, JH,H = 6.0 Hz,
4H, OCH), 6.98 (s, 4H, C6H2), 10.43 (s, 2H, NH); 31P{ H} NMR δ (ppm): 2.6.
1
Crystal Structure Determination and Refinement
The X-ray data for HLIII were collected on a STOE IPDS-II diffractometer with
graphite-monochromatized Mo-Kα radiation generated by a fine-focus X-ray tube operated
at 50 kV and 40 mA. The images were indexed, integrated, and scaled using the X-Area data
reduction package.21 Data were corrected for absorption using the PLATON program.22 The
structures were solved by direct methods using the SHELXS-97 program23 and refined first
isotropically and then anisotropically using SHELXL-97.23 Hydrogen atoms were revealed
from ꢀρ maps, and those bonded to C were refined using appropriate riding models. H
atoms bonded to N were freely refined.
CCDC 737532 (HLIII) contains the supplementary crystallographic data. 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, Cambridge CB2 1EZ,
UK; fax: (+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.

2432
D. A. SAFIN ET AL.
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