2D hydrogen bond networks in the crystals of [(NH4 · H2O)2][(RO)(Fc)P(S)2]2 (R = 3-(BzO)-Bz, 4-(n-Bu)-Bz, Bz = benzyl)

Article abstract of DOI:10.1016/j.jorganchem.2007.08.014

Herein we report on the preparation of hydrated ammonium salts of the dithiophosphonic acids (RO)(Fc)P(S)(SH) (R = derivative of benzyl) featuring [(NH₄ · H₂O)₂]²⁺ cations formed by N-H?O hydrogen bonds. Interac

Full text of DOI:10.1016/j.jorganchem.2007.08.014

Journal of Organometallic Chemistry 692 (2007) 5295–5302
www.elsevier.com/locate/jorganchem
2D hydrogen bond networks in the crystals
of [(NH4 Æ H2O)2][(RO)(Fc)P(S)2]2 (R = 3-(BzO)-Bz,
4-(n-Bu)-Bz, Bz = benzyl)
´
´
´
Marıa del C. Hernandez-Galindo, Vojtech Jancik, Monica M. Moya-Cabrera,
*
´
Ruben A. Toscano, Raymundo Cea-Olivares
Instituto de Quı´mica, Universidad Nacional de Me´xico, Circuito Exterior s/n, Del. Coyoaca´n, 04510, Me´xico, D.F., Me´xico
Received 27 June 2007; received in revised form 9 August 2007; accepted 9 August 2007
Available online 16 August 2007
Dedicated to Prof. Ionel Haiduc on the occasion of his 70th birthday.
Abstract
Herein we report on the preparation of hydrated ammonium salts of the dithiophosphonic acids (RO)(Fc)P(S)(SH) (R = ꢁderivative of
benzyl) featuring [(NH4 Æ H2O)2]2+ cations formed by N–Hꢀ ꢀ ꢀO hydrogen bonds. Interaction of these cations with the PS2 units gives
rise to unprecedented 2D networks, formed solely by hydrogen bonds. These unique networks containing two- and three centered hydro-
gen bonds are valuable examples of the acceptor properties of sulfur atoms.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: 2D network; Ammonium ion; Water; Hydrogen bond; Phosphorus
1. Introduction
are not many reports on the acceptor properties of sulfur
atoms, the hydrogen bonds dealing with sulfur as the
acceptor atom have proven to be determinant in the tuning
of the reactivity of the Znꢀ ꢀ ꢀcystein thiolate moiety and the
Fe–S clusters in proteins [6,7].
The concept of Nebenvalenz published in 1902 by Wer-
ner [1], and the term ‘‘Hydrogen bridge atoms’’ used by
Atsbury in 1933 [2] were one of the first stones in the
description of the phenomenon defined later as a Hydrogen
Bridge or a Hydrogen Bond. Nonetheless, it was Pauling
who first introduced in 1939 the concept of hydrogen bond
as an important principle in structural chemistry in The
Nature of Chemical bond [3]. Currently, its importance
has been well documented by the over 355,000 references
in the chemical abstracts and by numerous monographs
[4]. Moreover, many papers describing unusual 1D, 2D
or 3D water chains, sheets or clusters, respectively, formed
by hydrogen bonds have been reported [5]. Although, there
In our group, there is a long history in the chemistry of
phosphorus-chalcogen moieties containing ligands as
HN(PR2E)2 or HN(PR2E)(PR02E) (E = O, S, Se and their
combination, R, R0 = alkyl, aryl, alkoxyl), (RO)2P(S)(SH)
(R = alkyl, aryl) and their main-group elements derivatives
[8]. Recently, we have focused our research on investigating
the influence of the R group in tellurium complexes of the
[(RO)(Fc)P(S)2]ꢁ (R = benzyl derivative) anion on the
resulting geometry. We decided to use the method of Fac-
kler for the preparation of ferrocene bearing ligands [9],
although several other preparations have been published
[10], as the resulting ammonium salts were reported to be
stable. During the isolation of the ammonium salts
[NH4][(RO)(Fc)P(S)2] (R = 3-(BzO)-Bz (1a), 4-(n-Bu)-Bz
(2a), Bz = benzyl) we observed inclusion of water into the
*
Corresponding author. Tel.: +52 55 56 22 45 05; fax: +52 55 56 16 22
17.
E-mail address: cea@servidor.unam.mx (R. Cea-Olivares).
0022-328X/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.08.014

5296
M.d.C. Herna´ndez-Galindo et al. / Journal of Organometallic Chemistry 692 (2007) 5295–5302
samples and the formation of hydrated salts [(NH4 Æ
H2O)2][(RO)(Fc)P(S)2]2 (R = 3-(BzO)-Bz (1), 4-(n-Bu)-Bz
(2), Bz = benzyl). Compounds 1 and 2 contain unusual
examples of 2D networks formed solely by hydrogen bonds
and involving the rare [(NH4 Æ H2O)2]2+ cation.
TMS): d = 66.4 (CH2–O), 70.1 (Ar–CH2–O–Ar), 70.5 (C
of Cp unsubst.), 70.8, 70.9 (C of Cp subst.), 71.6 (d,
1J(C,P) = 16 Hz, C of Cp subst.), 114.5, 114.8, 120.7,
127.8, 128.1, 128.7, 129.9, 136.9, 139.5, 158.9 ppm (C of
Ar); 31P{1H} NMR ((CDCl3/DMSO-d6), 20 ꢁC, 85%
H3PO4): d = 107.4 ppm. Mass Spec (ESI-ITMS): m/z 493
[MꢁNH4]ꢁ.
2. Experimental
2.1. Materials
2.3.2. Synthesis of [(NH4 Æ H2O)2][(3-(BzO)-BzO)
(Fc)P(S)2]2 (1)
Gaseous ammonia was purchased from Praxair and
dried by passing through a column filled with sodium wire.
All solvents were dried prior to use.
1a (1.00 g, 1.96 mmol) was dissolved in wet THF
(30 mL) and stirred for 10 min. All the volatiles were
removed under vacuum to give 1 as a brown-orange micro-
crystalline material in a quantitative yield (1.04 g, 100%);
m.p. 154–155 ꢁC. Elemental analysis (%) calcd. for
C24H28FeNO3PS2 (529.43): C 54.45, H 5.33, N 2.65; found:
2.2. Physical measurements
~
Infrared spectra were recorded as CsI powders in the
range 4000–250 cmꢁ1 on a Bruker Tensor 27 Fourier-trans-
form spectrometer using the method of diffused reflectance;
1H, 13C and 31P NMR spectra were recorded using a JEOL
ECLIPSE 300 NMR spectrometer. Mass spectra (ESI-
ITMS) were recorded using a Bruker Daltonics Esquive
6000 spectrometer. Elemental analyses (C, H, N) were car-
ried out by Galbraith Laboratories Inc. (Knoxville, TN).
C 54.12, H 5.42, N 2.55%; IR (CsI): m 3393 (m br, m H2O),
3261 (s br, mH2O), 2941 (vs br, mNH + mCH), 1598 (s, d
NH4+), 1444 (s, mP–C), 1175 (s, mP–O–C), 1013 (vs, mP–
O–C), 823 (vs, d CH2), 651 (s, masymP–S), 586 cmꢁ1 (s,
m
symP–S). 1H NMR ((CDCl3/DMSO-d6), 20 ꢁC, TMS):
+
d = 1.32 (br s, 4 + 2H, NH4 and H2O), 4.20 (bs,
5 + 2H, H of Cp unsubst. + subst.), 4.61 (bs, 2H, H of
3
Cp subst.), 4.87 (d, 2H, J(H,P) = 8.5 Hz, CH2–O), 4.96
(s, 2H, Ar–CH2–O–Ar), 6.75–7.37 ppm (m, 9H, H of Ar);
13C NMR ((CDCl3/DMSO-d6), 20 ꢁC, TMS): d = 65.8 (s,
CH2–O), 70.0 (s, Ar–CH2–O–Ar), 70.4 (C of Cp unsubst.),
2.3. Preparation of compounds
1
The preparation of the anhydrous salts 1a and 2a were
performed in a dry and oxygen-free atmosphere (N2 or
Ar) by using Schlenk-line and glove-box techniques. Ferr-
ocenyl Lawesson’s Reagent [11] (FcLR) was prepared
using the literature procedures.
70.4, 70.4 (C of Cp subst.), 71.7 (d, J(C,P) = 14 Hz, C of
Cp subst.), 114.2, 114.2, 120.5, 127.7, 127.9, 128.6, 129.4,
137.1, 140.1, 158.8 ppm (H of Ar); 31P{1H} NMR
((CDCl3/DMSO-d6), 20 ꢁC, H3PO4): d = 108.4 ppm.
2.3.3. Synthesis of [NH4][(4-(n-Bu)-BzO)(Fc)P(S)2]
(2a)
2.3.1. Synthesis of [NH4][(3-(BzO)-BzO)(Fc)P(S)2]
(1a)
A mixture of FcLR (0.85 g, 1.52 mmol) and 4-n-butyl-
benzyl alcohol (0.50 g, 3.04 mmol) in benzene (40 mL)
was refluxed for 3 h. The resulting brown-orange solution
was placed in an ice bath, and stirred for 30 min. Anhy-
drous gaseous NH3 was slowly bubbled through the solu-
tion at 0 ꢁC for 1 h. The color of the solution changed
from brown-orange to dark green and a small amount of
insoluble material precipitated out. The reaction mixture
was filtrated and all volatiles were removed under vacuum.
The crude product was recrystallized from CH2Cl2/hexane
mixture to yield 2a as a pale green yellow powder. Yield:
0.79 g (56%); m.p. 114–116 ꢁC. Elemental analysis (%)
calcd. for C21H28FeNOPS2 (461.40): C 54.67, H 6.12, N
A mixture of FcLR (1.00 g, 1.78 mmol) and 3-benzyl-
oxybenzyl alcohol (0.76 g, 3.56 mmol) in benzene (40 mL)
was refluxed for 3 h. The resulting brown-orange solution
was placed in an ice bath, and the mixture stirred for
30 min. Anhydrous gaseous NH3 was slowly bubbled
through the solution at 0 ꢁC for 1 h. The color of the solu-
tion changed from orange to dark brown and a small
amount of insoluble material precipitated out. The reaction
mixture was filtrated and all volatiles were removed under
vacuum. The crude product was recrystallized from a
CH2Cl2/hexane mixture to yield 1 as a pale yellow powder.
Yield: 1.42 g (78%); m.p. 116–118 ꢁC; Elemental analysis
(%) calcd. for C24H26FeNO2PS2 (511.42): C 56.37, H
5.12, N 2.74; found: C 56.62, H 5.20, N 2.81%; IR (CsI):
~
3.04; found: C 54.32, H 6.05, N 3.10%; IR (CsI): m 2955
(vs br, mNH + mCH), 1514 (m, d NH4+), 1406 (s, mP–C),
1171 (m, mP–O–C), 986 (s, mP–O–C), 822 (s, d CH2), 675
(s, masymP–S), 579 cmꢁ1 (s, msymP–S). 1H NMR (CDCl3,
20 ꢁC, TMS): d = 0.91 (t, 3H, 3J(H,H) = 7.6 Hz, CH2–
m 2905 (vs br, mNH + mCH), 1598 (s, d NH4+), 1444 (s,
~
mP–C), 1272 (s, mP–O–C), 1046 (m, mP–O–C), 824 (m, d
CH2), 672 (vs, masymP–S), 584 cmꢁ1 (s, msymP–S). 1H
NMR ((CDCl3/DMSO-d6), 20 ꢁC, TMS): d = 4.26 (s, 5H,
H of Cp), 4.32 (bs, 2H, H of Cp), 4.60 (bs, 2H, H of
3
CH3), 1.33 (sext, 2H, J(H,H) = 7.6 Hz, CH2–CH2–CH3),
1.57 (q, 2H,3J(H,H) = 7.6 Hz, CH2–CH2–CH3), 2.57 (t,
2H,3J(H,H) = 7.6 Hz, CH2–CH2–Ar), 4.26 (s, 5H, H of
Cp unsubst.), 4.30 (bs, 2H, H of Cp subst.), 4.58 (bs, 2H,
H of Cp subst.), 4.93 (d, 2H,3J(H,P) = 8.6 Hz, CH2–O),
3
Cp), 4.90 (d, J(H,P) = 8.3 Hz, 2H, CH2–O), 5.01 (s, 2H,
Ar–CH2–O–Ar), 6.76 (br s, 4H, NH4+), 6.86–7.43 ppm
(m, 9H, H of Ar); 13C NMR ((CDCl3/DMSO-d6), 20 ꢁC,

M.d.C. Herna´ndez-Galindo et al. / Journal of Organometallic Chemistry 692 (2007) 5295–5302
5297
6.81 (bs, 4H, NH4+), 7.13–7.28 ppm (4H, H of Ar); 13C
(CDCl3, 20 ꢁC, TMS): d = 14.1 (CH2–CH3), 22.5 (CH2–
CH3), 33.7 (CH2–CH2–CH3), 35.5 (CH2–Ar), 66.3 (CH2–
O), 70.5 (C of Cp unsubst.), 70.7, 70.8 (C of Cp subst.),
and refinement details for compounds 1 and 2 are pre-
sented in Table 1. Selected bond lengths and angles for 1
and 2 are given in Table 2.
1
71.5 (d, J(C,P) = 15 Hz, C of Cp subst.), 128.3, 128.8,
Table 1
135.0, 142.9 ppm (C of Ar); 31P{1H} NMR (CDCl3,
20 ꢁC, H3PO4): d = 106.5 ppm. Mass Spec (ESI-ITMS):
m/z 443 [MꢁNH4]ꢁ.
Crystallographic data for the structural analyses of compounds 1 and 2
1
2
Empirical formula
Formula weight
Crystal system
Space group
C24H28FeNO3PS2 C21H30FeNO2PS2
529.41
Monoclinic
P21/c
479.40
Triclinic
2.3.4. Synthesis of [(NH4 Æ H2O)2][(4-(n-Bu)-BzO)
(Fc)P(S)2]2 (2)
ꢀ
P1
2a (1.00 g, 2.17 mmol) was dissolved in wet THF
(30 mL) and stirred for 10 min. All the volatiles were
removed under vacuum to give 1 as a brown-orange micro-
crystalline material in a quantitative yield (1.04 g, 100%);
m.p. 74–76 ꢁC. Elemental analysis (%) calcd. for C21H30Fe-
NO2PS2 (479.40): C 52.61, H 6.31, N 2.92; found: C 51.45,
Temperature, K
173(2)
0.71073
21.754(4)
9.316(2)
12.445(3)
90
104.78(3)
90
2439(1)
4
173(2)
0.71073
9.426(2)
11.747(3)
21.338(4)
74.19(3)
82.79(3)
89.05(3)
2255(1)
4
˚
Wavelength, A
˚
a, A
˚
b, A
˚
c, A
a, ꢁ
b, ꢁ
c, ꢁ
~
H 6.12, N 2.83%; IR (CsI): m 3385 (vs br, mH2O), 2957 (vs
3
˚
br, mNH + mCH), 1514 (m, d NH4+), 1416 (s, mP–C), 1177
(m, mP–O–C), 1009 (m, mP–O–C), 821 (m, d CH2), 652 (s,
Volume, A
Z
Densitycalc, g cmꢁ3
Absorption coefficient, mmꢁ1
F(000)
1.442
0.882
1104
1.412
0.942
1008
m
asymP–S), 484 cmꢁ1 (m, msymP–S). 1H NMR ((CDCl3),
20 ꢁC, TMS): d = 0.81 (t, 3H, 3J(H,H) = 7.4 Hz, CH2–
3
Crystal size, mm3
h Range for data collection, ꢁ
Index ranges
0.25 · 0.21 · 0.08 0.49 · 0.28 · 0.28
CH3), 1.23 (sext., 2H, J(H,H) = 7.4 Hz, CH2–CH3), 1.46
(q, 2H, 3J(H,H) = 7.4 Hz, CH2–CH2–CH3), 2.40 (s,
2.39–25.35
ꢁ25 6 h 6 26
ꢁ11 6 k 6 11
ꢁ14 6 l 6 5
9804
4320 (0.0396)
4320/7/307
1.019
0.0420, 0.0917
0.0559, 0.0984
0.406/ꢁ0.254
1.80–25.06
+
3
ꢁ11 6 h 6 11
ꢁ13 6 k 6 13
ꢁ25 6 l 6 25
24457
7940 (0.0346)
7940/34/543
1.034
0.0348, 0.0826
0.0415, 0.0863
0.525/ꢁ0.201
4 + 2H, NH4 and H2O), 2.49 (t, 2H, J(H,H) = 7.4 Hz,
CH2–CH2–Ar), 4.17 (dd, 2H, 3J(H,H) = 3.9 Hz,
3J(H,H) = 4.1 Hz, H of Cp subst.), 4.20 (s, 5H, H of Cp
unsubst.), 4.58 (s, 2H, 3J(H,H) = 3.9 Hz, 3J(H,H) =
4.1 Hz, H of Cp subst.), 4.84 (d, 2H, 3J(H,P) = 8.3 Hz,
CH2–O), 7.00–7.20 ppm (m, 4H, H of Ar); 13C (CDCl3,
20 ꢁC, TMS): d = 14.0 (CH2–CH3), 22.5 (CH2–CH3), 33.7
(CH2–CH2–CH3), 35.5 (CH2–CH2–Ar), 66.4 (s, CH2–O),
70.5 (C of Cp unsubst.), 70.5, 70.8 (C of Cp subst.), 71.6
Reflections collected
Independent reflections (Rint
Data/restraints/parameters
Goodness-on-fit on F2
R1,a wR2b (I > 2r(I))
)
R1,a wR2b (all data)
Largest difference in peak/hole,
ꢁ3
˚
e A
1
P
P
a
(d, J(C,P) = 14 Hz, C of Cp subst.), 128.3, 128.7, 135.0,
R = iFoj ꢁ jFci/ jFoj.
P
P
142.8 ppm (C of Ar); 31P{1H} NMR (CDCl3, 20 ꢁC,
TMS): d = 106.8 ppm.
wR2 ¼ ½ wðF 2o ꢁ F c2Þ = wðF 2oÞ ꢂ
.
2
2 1=2
b
2.4. X-ray data collection and structure solution and
refinement
Table 2
˚
Selected bond lengths [A] and angles [ꢁ] of 1 and 2
Compound 1
P(1)–S(1)
P(1)–S(2)
P(1)–O(2)
P1(1)–C(15)
S(1)–P(1)–S(2)
Orange block-shaped single crystals of compounds 1
and 2 were obtained by slow evaporation of their saturated
solutions in wet THF. A suitable crystal of each compound
was covered with paraffin oil, mounted on a nylon loop,
and placed immediately to the cold nitrogen stream
(173 K). Diffraction data for 1 and 2 were collected on a
Bruker three-circle diffractometer equipped with an APEX
CCD area-detector using graphite monochromated Mo Ka
2.013(1)
1.968(1)
1.606(2)
1.782(2)
S(1)–P(1)–O(2)
S(2)–P(1)–O(2)
S(1)–P(1)–C(15)
S(2)–P(1)–C(15)
O(2)–P(1)–C(15)
108.8(1)
111.9(1)
108.0(1)
113.6(1)
98.9(1)
114.5(1)
Compound 2
Molecule 1
P(1)–S(1)
P(1)–S(2)
P(1)–O(3)
2.012(1)
1.971(1)
1.607(2)
1.783(2)
S(1)–P(1)–O(3)
S(2)–P(1)–O(3)
S(1)–P(1)–C(12)
S(2)–P(1)–C(12)
O(3)–P(1)–C(12)
108.7(1)
111.6(1)
108.5(1)
113.2(1)
99.1(1)
˚
radiation (k = 0.71073 A). Structures were solved by direct
methods (SHELXS-97) [12] and refined by full-matrix least-
squares methods on F2 with SHELXL-97 [13]. The non-
hydrogen atoms were refined anisotropically; hydrogen
atoms were included at geometrically idealized positions
and refined with the riding model except those attached
to nitrogen and oxygen, which were localized from the elec-
tron density map and refined with distance restrains with
Uij set to 1.5 times the Uij of the parent atom. Crystal data
P1(1)–C(12)
S(1)–P(1)–S(2)
114.6(1)
Molecule 2
P(2)–S(3)
P(2)–S(4)
P(2)–O(4)
P(2)–C(33)
S(3)–P(2)–S(4)
2.012(1)
1.968(1)
1.608(2)
1.786(2)
S(3)–P(2)–O(4)
S(4)–P(2)–O(4)
S(3)–P(2)–C(33)
S(4)–P(2)–C(33)
O(4)–P(2)–C(33)
108.6(1)
111.8(1)
108.1(1)
113.1(1)
99.4(1)
114.8(1)

5298
M.d.C. Herna´ndez-Galindo et al. / Journal of Organometallic Chemistry 692 (2007) 5295–5302
ꢁ1
~
3. Results and discussion
at m 3393, 3261 for 1 and 3385 cm for 2 – whose broad
character suggests presence of hydrogen bonding.
Compounds 1a and 2a were prepared according the
method of Fackler [9]. The equimolar amounts of the
appropriate benzylic alcohol were refluxed with the Ferr-
ocenyl Lawesson’s Reagent FcP(S)(l-S)2P(S)Fc [11]
(FcLR) (Fc = ferrocenyl) in benzene for 3 h. The solution
was then placed in an ice bath for 30 min to cool to 0 ꢁC
and dry gaseous ammonia was bubbled through during
one hour at this temperature. Filtration of the resulting
suspension followed by the evaporation of all volatiles
under vacuum and recrystallization of the crude product
from a CH2Cl2/hexane mixture, afforded the products
[NH4][(RO)(Fc)P(S)2] (R = 3-(BzO)-Bz (1a); R = 4-(n-
Bu)-Bz (2a); Bz = benzyl) in moderate yields. Recrystalliza-
tion of 1a and 2a from wet THF resulted in a formation of
microcrystalline materials identified as [(NH4 Æ H2O)2][(R-
O)(Fc)P(S)2]2 (R = 3-(BzO)-Bz (1); R = 4-(n-Bu)-Bz (2))
by means of IR, ESI-MS (negative ions), multinuclear
NMR techniques and unambiguously by X-ray structural
analysis. Scheme 1 summarizes the preparation of com-
pounds 1a, 1, 2a and 2.
3.2. Structure of complexes 1 and 2
Compound 1 crystallizes in the monoclinic space group
P21/c with one molecule in the asymmetric unit, whereas
compound 2 crystallizes in a triclinic space group P1 with
ꢀ
two independent molecules in the asymmetric unit. Their
crystal structures are shown in Fig. 1 (compound 1) and
Fig. 2 (compound 2).
The X-ray structural analysis revealed the presence of an
unusual centrosymmetric cation [(NH4 Æ H2O)2]2+ formed
by four hydrogen bonds between the N–H protons from
the ammonium ions and the oxygen atoms of the water
molecules in both complexes 1 and 2, respectively. The pro-
1
3.1. H and 31P NMR and IR studies
The inclusion of water had only a small effect on the 31
P
NMR spectra (d 107.4 (1a), 108.4 (1), 106.5 (2a), 106.8 ppm
1
(2)), but had a great effect on the position of the H NMR
+
signal for the NH4 protons. Thus, the peak can be found
at d 6.76 ppm for 1a as a broad singlet, whereas the inclu-
sion of water causes this peak to move upfield to d
1.32 ppm (includes now also the protons from water) in
case of 1. The situation is similar for 2a and 2 and the sig-
nals can be found at d 6.81 and 2.4 ppm (includes now also
the protons from water). The difference between the chem-
ical shift in 1 and 2 is most probably caused by the presence
of DMSO-d6 used to support the solubilization of 1 in the
NMR sample. The inclusion of water can be further evi-
denced by the IR spectroscopy – water absorption bands
Fig. 1. Thermal ellipsoid plot of 1 at 50% level. Carbon-bound hydrogen
atoms are omitted for clarity.
Fe
Fe
S
S
S
S
2 ROH
P
P
2
P
S
benzene
reflux
O
R
SH
Fe
NH3 (g) (ex.)
Fe
Fe
THF
2 H2O
S
S
S
S
[(NH4 H2O)2]2
[NH ]
2
3
P
P
O
R
O
R
2
1
1a
R = 3-(BzO)-Bz
2 R = 4-(n-Bu)-Bz
R = 3-(BzO)-Bz
2a R = 4-(n-Bu)-Bz
Bz = benzyl
Fig. 2. Thermal ellipsoid plot of 2 at 50% level. Carbon-bound hydrogen
Scheme 1. Preparation of 1a, 1, 2a, 2.
atoms are omitted for clarity.

M.d.C. Herna´ndez-Galindo et al. / Journal of Organometallic Chemistry 692 (2007) 5295–5302
5299
found search in the CSD database gave to our surprise only
18 examples of such cation [14a]. Only in three cases, the
cation is not localized on any symmetry element, as was
also found in 2 [14b]. Moreover, these cyclic cations are
in 1 and 2 bridged by the [(RO)(Fc)P(S)2]ꢁ units into
unprecedented 2D networks formed strictly by N–Hꢀ ꢀ ꢀO,
N–Hꢀ ꢀ ꢀS or O–Hꢀ ꢀ ꢀS two or three centered hydrogen
bonds (Fig. 3) [15]. These 2D networks are localized in
the (100) plane in the crystal of 1, or in the (001) plane
in case of 2, respectively, while the organic residues and
ferrocenyl moieties are in both cases filling the cell. This
behavior can be compared to the hydrophobic and hydro-
philic attractions present in cell membranes in biological
systems.
There are numerous publications and reviews about
hydrogen bonding in proteins, where the acceptor atom is
either oxygen or nitrogen [4], but the publications corre-
sponding to hydrogen bonding – where the acceptor atom
is sulfur – are relatively scarce [6,7,16]. Therefore the defi-
nition regarding the distance between the hydrogen and
sulfur atom which can be still considered as a part of the
A–Hꢀ ꢀ ꢀS (A = O,N) hydrogen bond is not clear. The Jef-
frey criterion for hydrogen bond used also by the Interna-
tional Union of Crystallography [17] defines the largest
distance between the hydrogen and the acceptor atoms as
˚
vdWR(H) + vdWR(A) ꢁ 0.12 A (vdWR = van der Waals
˚
˚
Radii; which would be 2.60 A for Hꢀ ꢀ ꢀO, 2.63 A for
˚
Hꢀ ꢀ ꢀN and 2.88 A for Hꢀ ꢀ ꢀS, respectively, for these hydro-
gen – acceptor pairs), but longer distances are commonly
accepted for asymmetric three centered hydrogen bonds
occurring in proteins. The major components for such
˚
bonds have the Oꢀ ꢀ ꢀH bond lengths from 1.6 to 2.9 A (peak
˚
at 2.1 A) with angles 90 to 175ꢁ, whereas the minor compo-
˚
˚
nents have bond lengths from 2.05 to 3.0 A (peak at 2.8 A)
with angles 90–175ꢁ [18]. Thus, taking into account the dif-
˚
˚
ference in vdW radii of oxygen (1.62 A) and sulfur (1.80 A)
[19] – for a sulfur atom involved in an asymmetric three
centered hydrogen bond – the distance to the hydrogen
˚
could be up to 3.18 A. One can argue, that the basicity of
the sulfur atom is lower than that of oxygen [20], but the
fact, that the P–S bond lengths in 1 and 2 are very similar
(2.013(1) and 1.969(1) for 1 and 2.012(1), 1.971(1), 2.012(1)
Fig. 3. First column: compound 1, second column: compound 2. View along the a cell axis in the crystal of 1, along c axis in the crystal of 2, respectively,
without (a) and with (b) hydrogen bonds. View along the b cell axis in the crystal of 1, along a axis in the crystal of 2, respectively (c). All organic residues
have been omitted for clarity.

5300
M.d.C. Herna´ndez-Galindo et al. / Journal of Organometallic Chemistry 692 (2007) 5295–5302
Table 3
and 1.968(1) in 2) compared to the theoretical values for a
˚
Bond lengths [A] and angles [ꢁ] for the hydrogen bonds in 1 and 2
˚
˚
single (2.09 A) [21] and double (1.86 A) [22] phosphorus
sulfur bond – suggests the occurrence of delocalization of
the negative charge between both sulfur atoms of the PS2
unit, thus enhancing their basicity. Although the cell
parameters and the anions for 1 and 2 are different, the
connectivity of the atoms in the 2D network is in both
compounds very similar (Fig. 3 and supporting informa-
tion) and the parameters for the hydrogen bonds are nearly
identical (Table 3). All the protons from the
[(NH4 Æ H2O)]+ pair are contributing to six different hydro-
gen bonds (two sets of six bonds for the two independent
molecules in 2), which can be further divided into 4 two
centered and 2 threeꢁcentered hydrogen bonds. Both sulfur
atoms from the PS2 unit and the oxygen atom from the
water molecule act as acceptor atoms in these bonds. For
clarity, only the acceptor atom type and not the symmetry
code will be noted in the following lines. The two centered
hydrogen bonds involve protons H(3) (acceptor O) and
H(4) (acceptor S) from the ammonium cation, H(5) (accep-
tor S) and H(6) (acceptor S) from the water molecule (for 1
and molecule 1 of 2), the protons H(9) (acceptor O) and
H(10) (acceptor S) from the second ammonium cation
and H(11) (acceptor S) and H(12) (acceptor S) from the
second molecule of water in 2. These hydrogen bonds have
the values of the D–Hꢀ ꢀ ꢀA angle of 165–176ꢁ and the
D–Hꢀ ꢀ ꢀA
Compound 1
d D–H
d Hꢀ ꢀ ꢀA
d Dꢀ ꢀ ꢀA
\DHA
N(1)–H(1)ꢀ ꢀ ꢀS(1)#1
N(1)–H(1)ꢀ ꢀ ꢀS(2)#1
N(1)–H(2)ꢀ ꢀ ꢀS(2)#2
N(1)–H(2)ꢀ ꢀ ꢀO(1)#3
N(1)–H(3)ꢀ ꢀ ꢀO(1)
N(1)–H(4)ꢀ ꢀ ꢀS(1)#3
O(1)–H(5)ꢀ ꢀ ꢀS(1)#2
O(1)–H(6)ꢀ ꢀ ꢀS(1)#4
0.85(2)
0.85(2)
0.85(2)
0.85(2)
0.85(2)
0.86(2)
0.81(3)
0.83(3)
3.00(3)
2.53(2)
2.94(3)
2.68(3)
1.97(2)
2.43(2)
2.49(3)
2.47(3)
3.618(3)
3.325(3)
3.568(3)
3.089(4)
2.809(4)
3.279(3)
3.284(3)
3.297(2)
131(3)
155(3)
132(3)
111(3)
170(3)
169(3)
170(4)
176(4)
Compound 2
Molecule 1
N(1)–H(1)ꢀ ꢀ ꢀS(1)#1
N(1)–H(1)ꢀ ꢀ ꢀS(2)#1
N(1)–H(2)ꢀ ꢀ ꢀS(2)#2
N(1)–H(2)ꢀ ꢀ ꢀO(1)#3
N(1)–H(3)ꢀ ꢀ ꢀO(1)
N(1)–H(4)ꢀ ꢀ ꢀS(3)#4
O(1)–H(5)ꢀ ꢀ ꢀS(1)#2
O(1)–H(6)ꢀ ꢀ ꢀS(3)
0.88(1)
0.88(1)
0.88(1)
0.88(1)
0.89(1)
0.88(1)
0.87(2)
0.87(2)
3.03(2)
2.49(2)
3.01(3)
2.49(3)
1.92(1)
2.42(1)
2.41(2)
2.48(2)
3.659(3)
3.300(2)
3.572(3)
3.060(3)
2.809(3)
3.291(2)
3.277(2)
3.300(2)
130(2)
153(2)
124(2)
123(2)
175(3)
170(3)
176(3)
172(3)
Molecule 2
N(2)–H(7)ꢀ ꢀ ꢀS(3)
N(2)–H(7)ꢀ ꢀ ꢀS(4)
N(2)–H(8)ꢀ ꢀ ꢀS(4)#2
N(2)–H(8)ꢀ ꢀ ꢀO(2)#2
N(2)–H(9)ꢀ ꢀ ꢀO(2)
N(2)–H(10)ꢀ ꢀ ꢀS(1)#2
O(2)–H(11)ꢀ ꢀ ꢀS(1)#5
O(2)–H(12)ꢀ ꢀ ꢀS(3)#2
Symmetry transformations used to generate equivalent atoms for com-
pound 1: #1 x, y ꢁ 1, z; #2 ꢁx, ꢁy + 1, ꢁz + 1; #3 ꢁx, y ꢁ 1/2, ꢁz + 3/2;
#4 x,ꢁy + 3/2, z ꢁ 1/2; Symmetry transformations used to generate
equivalent atoms for compound 2: #1ꢁx + 1, ꢁy + 1, ꢁz; #2 ꢁx + 1, ꢁy,
ꢁz; #3 x ꢁ 1, y, z; #4 x ꢁ 1, y ꢁ 1, z; #5 ꢁx, ꢁy, ꢁz.
0.89(1)
0.89(1)
0.88(1)
0.88(1)
0.89(1)
0.89(1)
0.88(2)
0.87(2)
2.95(2)
2.51(2)
2.98(2)
2.54(3)
1.93(1)
2.43(1)
2.42(2)
2.44(2)
3.610(3)
3.314(4)
3.559(3)
3.028(3)
2.815(3)
3.298(2)
3.297(2)
3.294(2)
133(2)
151(2)
125(2)
115(2)
172(3)
165(3)
174(3)
166(3)
˚
Hꢀ ꢀ ꢀA separation 1.92–1.97 A (acceptor O) or 2.41–
˚
2.49 A (acceptor S), respectively, and can be thus consid-
ered as strong [4a,18]. The three centered hydrogen bonds
are asymmetric and involve the remaining N–H protons
H(1) (acceptors S, S), H(2) (acceptors O – main compo-
nent, S – minor component) for 1 and molecule 1 of 2,
Fig. 4. Detail of the hydrogen bonding in the crystal of 1. View along the a cell axis. All organic residues and the symmetry codes have been omitted for
clarity.

M.d.C. Herna´ndez-Galindo et al. / Journal of Organometallic Chemistry 692 (2007) 5295–5302
5301
[2] W.T. Atsbury, H.J. Woods, Trans. R. Soc. A232 (1933) 333–394.
[3] L. Pauling, in: The Nature of the Chemical Bond, Cornel University
Press, Ithaca, NY, USA, 1939.
and H(7) (acceptors S, S), H(8) (acceptors O – main com-
ponent, S – minor component) in molecule 2 of 2. The
binding of the protons to two instead of one acceptor atom
is obvious from the similar Hꢀ ꢀ ꢀA distances in all six bonds
[4] For example, see: (a) G.A. Jeffrey, W. Saenger, in: Hydrogen Bonding
in Biological Structures, Springer-Verlag, NY, USA, 1991;
(b) G.A. Jeffrey, in: An Introduction to Hydrogen BondingTopics in
Physical Chemistry, Oxford University Press, NY, USA, 1997;
(c) M. Alajarin, A.E. Aliev, A.D. Burrows, K.D.M. Harris, in:
Supramolecular Assembly via Hydrogen Bonds IStructure and
Bonding, Springer-Verlag, Berlin, Germany, 2004;
(d) G.R. Desiraju, T. Steiner, in: The Weak Hydrogen Bond: In
Structural Chemistry and BiologyInternational Union of Crystallog-
raphy Monographs on Crystallography, vol. 9, Oxford University
Press, Oxford, Great Britain, 2002.
˚
present in 1 and 2 (2.49–2.68 A for the major and 2.94–
˚
3.03 A for the minor component) and is also reflected in
less obtuse values for the D–Hꢀ ꢀ ꢀA angles – 111–155ꢁ. Fur-
˚
thermore, as mentioned above, values of 3 A are commonly
accepted for the minor component of a three centered
hydrogen bonds in proteins [18], thus, we can consider 1
and 2 as complexes containing asymmetric three centered
hydrogen bond having sulfur atoms as the acceptors. The
sulfur atom S(1) is involved in four hydrogen bonds (3
two centered and 1 three centered), whereas the atom
S(2) acts as an acceptor in 2 three centered hydrogen
bonds. For a full list of the parameters and details of these
hydrogen bonds, see Table 3. A detail of the hydrogen
bonding pattern with a numbering scheme for compound
1 is shown in Fig. 4. The fact, that it is not possible to dehy-
drate 1 and 2 back to 1a and 2a in vacuum at ambient tem-
perature, demonstrates the stability of this 2D network
formed solely by hydrogen bonds. The conversion of 1
and 2 back to 1a and 2a can be however achieved by heat-
ing 1 and 2 in vacuum for 5 h at 70 ꢁC.
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In summary, we have prepared two chemically and crys-
tallographically different systems containing nearly identical
2D network formed by wide hydrogen bonding between
water molecules, ammonium ions and [(RO)(Fc)P(S)2]ꢁ
units. These systems are valuable sources of information
regarding the sulfur acceptor properties in hydrogen bonds
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Acknowledgements
(d) S. Karlin, Z.-Y. Zhu, Proc. Natl. Acad. Sci. USA 94 (1997)
14231–14236;
(e) T. Simonson, N. Climent, Proteins 49 (2002) 37–48;
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This work was supported by PAPIIT Grant No.
IN209706. V.J. wishes to thank to UNAM for his postdoc-
toral fellowship.
Appendix A. Supplementary material
[8] For example, see: (a) J. Morales-Juarez, R. Cea-Olivares, M. Moya-
Cabrera, V. Garcia-Montalvo, A.R. Toscano, Main Group Chem. 4
(2005) 23–31;
CCDC 619853 and 619854 contain the supplementary
crystallographic data for 1 and 2. These data can be
obtained free of charge via http://www.ccdc.cam.ac.uk/
conts/retrieving.html (or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge
CB21EZ, UK; fax: +44 1223 336 033; or deposit@ccdc.ca-
m.ac.uk). Supplementary data associated with this article
can be found, in the online version, at doi: doi:10.1016/
j.jorganchem.2007.08.014.
(b) J. Morales-Juarez, R. Cea-Olivares, M.M. Moya-Cabrera, V.
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M. Lopez-Cardoso, P. Garcia y Garcia, R. Cea-Olivares, J. Organo-
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(e) M. Hernandez-Arganis, S. Hernandez-Ortega, R.A. Toscano, V.
Garcia-Montalvo, R. Cea-Olivares, Chem. Commun. (2004) 310–311.
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