The silver(I) coordination polymer [AgO2PPh2]n and unsupported A?Ag interactions derived from aminophosphinate and phosphinic acid

Article abstract of DOI:10.1016/j.poly.2015.06.033

Abstract The ligand N-tert-butyl-1,1-diphenylphosphinamine, Ph₂P-N(H)CMe₃, was prepared from tert-butylamine and diphenylchlorophosphine. The phosphine portion of the ligand became partially oxidized in air to form Ph₂P(O)

Full text of DOI:10.1016/j.poly.2015.06.033

Polyhedron 99 (2015) 87–95
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
The silver(I) coordination polymer [AgO PPh ] and unsupported
2
2 n
AgÁ Á ÁAg interactions derived from aminophosphinate and phosphinic
acid
⇑
Vashen Moodley, Londiwe Mthethwa, Michael N. Pillay, Bernard Omondi, Werner E. van Zyl
School of Chemistry and Physics, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban 4000, South Africa
a r t i c l e i n f o
a b s t r a c t
Article history:
2 3
The ligand N-tert-butyl-1,1-diphenylphosphinamine, Ph P-N(H)CMe , was prepared from tert-butylamine
Received 24 April 2015
Accepted 30 June 2015
Available online 4 July 2015
and diphenylchlorophosphine. The phosphine portion of the ligand became partially oxidized in air to
form Ph P(O)N(H)CMe , L1, whilst further oxidation led to diphenylphosphinic acid, Ph P(O)OH. X-ray
analysis revealed that ligand L1 was isolated in the solid-state in a dimeric polymorphic form, different
from the previously reported trimeric form. Ligand L1 was subsequently treated with solid AgSO CF in
THF which formed a rare silver(I) dinuclear complex of the type [Ag(CF SO ){OPPh N(H)CMe
Ag(OPPh N(H)CMe }]SO CF
2
3
2
3
3
Keywords:
3
3
2
3 2
}
Silver(I) complexes
Diphenylphosphinic acid
Aminophosphinate
Ligand unsupported
Dinuclear
{
2
3
)
2
3
3
, 1, and consists of ligand unsupported AgÁ Á ÁAg interactions of 2.89 Å
coordinating through two O donor atoms from the two separate silver units (A and B) and with no
coordination through the N atom. Further, silver unit A contains a 3-coordinate Ag(I) center, bent signif-
icantly from a linear geometry due to interaction from the triflate O donor atom, whilst unit B remained
essentially 2-coordinate and linear. The diphenylphosphinate reacted with solid AgSO
temperature and this led to an unusual Ag(I) coordination polymer, [Ag {( -O)OPPh
3
CF
}{O
3
in THF at room
PPh }] 2, con-
2
l
2
2
2
n
sisting of two different bonding modes of O-donor atoms in a 4-coordinate arrangement around the
Ag(I) center. Compounds L1, 1 and 2 were all obtained in moderate to good yields, and analyzed by single
1
31
crystal X-ray studies, solution H and P NMR, IR, and elemental analyses.
Ó 2015 Elsevier Ltd. All rights reserved.
1
. Introduction
hexacapped trigonal bipyramids [11], amongst others. However,
in contrast to the large number of cyclic and polyhedral Ag(I)
aggregates, those with linear geometries are more scarce [12]
although a common observation here is the formation of 1D infi-
nite Ag(I) nanowires [13]. A number of elegant crystal engineered
Ag(I) supramolecular frameworks and coordination complexes are
known containing both supported and unsupported weak
Ag(I)Á Á ÁAg(I) interactions [14]; the latter can also be extended to
cationic systems [15]. The majority of ligand types used to engen-
der Ag(I)Á Á ÁAg(I) interactions include carboxylic type spacers [16]
The metallophilic interactions between closed-shell d10 metal
ions of the coinage metals (Cu, Ag, Au) often have a strong struc-
tural and directional influence affecting the optical and electronic
properties of such complexes [1]. This phenomenon is frequently
observed in gold(I) complexes, with the term ‘‘aurophilicity’’ being
used to describe Au(I)Á Á ÁAu(I) interactions that theorists have attri-
bute to correlation and relativistic effects [2]. Silver(I), the lighter,
but not necessarily smaller [3] group 11 metal congener, has
diminished relativistic effects [4] but a significant number of com-
plexes with weak Ag(I)Á Á ÁAg(I) interactions, termed ‘‘argentophilic-
ity’’, has been observed [5]. Argentophilic interactions can be
further divided amongst the majority of ligand supported [6],
and a few ligand unsupported [7] types. Argentophilic interactions
also contributes to the formation of diverse Ag(I) geometries,
including simple tetrahedron [8] discrete octa- and decanuclear
silver clusters [9], triangulated dodecahedrons [10] and
including a trapped carbonate ion derived from atmospheric CO
2
[17]. Three different types of coordination polymers, one-dimen-
sional (1D) straight chain, 1D-columnar structure, and two-dimen-
sional (2D) layer structure, have been prepared by the
complexation of Ag(I) ions with bis(pyridyl) ligands linked by an
aromatic sulfonamide [18].
In contrast to O-donor carboxylates and N-donor pyridyls and
pyrazoles, the chemistry of phosphine chalcogenide silver(I) com-
plexes have been less explored, even though silver displays an abil-
ity to coordinate readily to both hard and soft donor atoms. The
first examples of silver phosphonites contained no X-ray structural
⇑
Corresponding author. Tel.: +27 (0) 31 260 3188; fax: +27 (0) 31 260 3091.
E-mail address: vanzylw@ukzn.ac.za (W.E. van Zyl).
http://dx.doi.org/10.1016/j.poly.2015.06.033
277-5387/Ó 2015 Elsevier Ltd. All rights reserved.
0

8
8
V. Moodley et al. / Polyhedron 99 (2015) 87–95
reports, but it was found the reactions between metal halides,
metal carbonyl halides, or metal olefin halides, and dialkyl
phenylphosphonite ligands performed in polar solvents afforded
a general route to an extensive series of uncharged complexes
point: 133–136 °C. 1H NMR, (CDCl
1.27 (9H, s, t-Bu), 7.33 (8H, m, Ph), 7.41 (2H, dd, Ph, JH–H = 6.72,
3
), d (ppm): 1.29 (1H, s, NH),
1
1
.54 Hz). 13C NMR, (CDCl
28.30 (ortho-ArC), 131.74 (meta-ArC), 135.70 (para-ArC).
), d: 19.51 ppm. Anal. Calc. for C16 20NOP: C, 70.31;
3 3 3
), d (ppm): 32.28 (CH ), 53.09 (CMe ),
31
P
[
[
19]. The versatility of the iminodiphosphine chalcogenide species
P(E)HNP(E)R ] (E = O, S, Se) renders them excellent ligand scaf-
NMR, (CDCl
3
H
R
2
2
H, 7.38; N, 5.12. Found: C, 70.40; H, 7.32; N, 5.08%. Selected IR data
À1
folds with which to probe the hard–soft behaviour of silver(I) [20].
Silver phosphinates have been used in catalysis for direct annula-
tions toward phosphorylated oxindoles [21] and a tetrasilver(I)
phosphonitocavitand [22] and silver(I) phosphonates have been
synthesized [23]. Structures and ligand conformations of Ag(I)
complexes containing phosphinic amide ligands have been
reported [24] as well as structural characterization of some
arylamidinium diphenylphosphinates forming one-, two- and
three-dimensional networks by charge-assisted hydrogen bonds
m
/cm : 1175 (s), 1109(s), 692 (s), 522 (s).
2.3. Preparation of
Ag(CF SO ){OPPh N(H)CMe } {Ag(OPPh N(H)CMe ) }]SO CF (1)
3
3
2
3 2 2 3 2 3 3
To a solution of L1 (0.394 g, 0.496 mmol) in THF (20 mL), silver
trifluoromethanesulfonate (0.0646 g, 0.251 mmol) was added, the
Schlenk tube was covered in foil to protect materials from light
sources. The mixture was stirred for 4 h at room temperature
3 3
and through the interaction of AgSO CF [25]. Thin films of silver
and
Dichloromethane was added and stirred for an additional 10 min,
and filtered through anhydrous MgSO . Solvent was removed in
vacuo to obtain a white powder. Yield: 0.134 g, 68% yield.
solvent
was
removed
under
reduced
pressure.
metal were deposited from tetraphenyldioxoimidodiphosphinato
silver(I) [26]. The N-aminodiphenylphosphine class of compounds
has been known for over 50 years [27] together with its oxidation
behavior toward oxygen and sulfur [28] and the facile acidic
4
1
Melting point: 147–149 °C. H NMR, (CDCl
3
), d (ppm): 1.64 (4H,
cleavage of the P–N bond [29].
À
s, NH), 1.30 (36H, s, t-Bu), 7.44 (32H, m, Ph), 7.89 (8H, dd, Ph,
Ironically, although AgO
2
PPh
2
is often used as an O
2
PPh
2
trans-
1
3
J
H–H = 6.68, 1.20 Hz). C NMR, (CDCl
3
), d (ppm): 32.29 (CH
3
),
fer reagent [30], it appears the present study reports the solid-state
structure of AgO PPh itself for the first time. In our ongoing
53.00 (CMe
(para-ArC).
3
), 128.29 (ortho-ArC), 131.42 (meta-ArC), 135.70
P NMR, (CDCl ), d: 19.49 ppm. Anal. Calc. for
3
2
2
3
1
studies of phosphor-1,1-dichalcogenates and aminophosphines of
group 11 metals [31], we report (i) a new dimeric polymorph of
an aminodiphenylphosphine derivative, an (ii) unusual ligand
unsupported silver(I) dinuclear complex containing the
C
62
H
76Ag
2
F
6
N
4
O
10
P
4
S
2
: C, 47.89; H, 4.93; N, 3.60. Found: C,
À1
47.90; H, 4.83; N, 3.68%. Selected IR data
(s), 1122(s), 678 (s), 542 (s).
m/cm : 3181(m), 1172
OPPh
coordination polymer of AgO
Ag–O and P–O bonding modes.
2
N(H)CMe
3
ligand and stabilized by triflate, and (iii) the
2
PPh containing different Ag–Ag,
2
2 2 2 2
2.4. Preparation of [Ag {(l-O)OPPh }{O PPh }], (2)
A Schlenk tube was charged with a solution of t-butylamine
2
. Experimental
.1. General
Unless otherwise stated, all reactions were carried out under an
(0.884 mL, 8.36 mmol) in THF (50 mL). A catalytic amount of
DMAP (0.102 g, 0.836 mmol) was added, and the solution was
allowed to stir for 5 min at room temperature. Triethylamine
2
(
1.800 mL, 12.54 mmol) was added and the solution was allowed
to stir for a further 5 min. Upon addition of chlorodiphenylphos-
phine (1.500 mL, 8.36 mmol) white precipitate formed,
Et
NÁHCl. The ensuing mixture was allowed to stir for approxi-
mately 3 h. The mixture was filtered through anhydrous MgSO
inert atmosphere of positive nitrogen gas flow using standard
Schlenk techniques. Reactions were stirred magnetically with a
Teflon coated stirrer-bar. Glassware was dried for 24 h at 160 °C
and assembled hot under a stream of dinitrogen gas. Diethyl ether,
tetrahydrofuran, and hexane were distilled over sodium wire using
a benzophenone-ketyl radical indicator. Dichloromethane was dis-
tilled over anhydrous calcium hydride. Room temperature refers to
a
3
4
and Celite into a separate pre-weighed Schlenk tube. The solvent
was removed in-vacuo and the Schlenk tube was re-weighed to
determine the yield. Thereafter, 40 mL of THF with a pre-deter-
3 3
mined amount of AgSO CF (2.14 g; 8.36 mmol) was added. The
2
3–25 °C; higher temperatures were obtained with the use of a sil-
solution was allowed to stir for 30 min and solvent was removed
1
icone-based oil bath. The following chemicals were purchased
from the Sigma–Aldrich company: chlorodiphenylphosphine,
t-butyl amine and silver trifluoromethanesulfonate. Deuterated
solvents were obtained from Merck. Nitrogen gas was obtained
from Afrox, South Africa.
in vacuo. Yield: 2.93 g, 54%; Melting point: 114–117 °C. H NMR,
(CDCl
7.69 (8H, dd, Ph, JH–H = 12.60, 7.20 Hz). C NMR, CDCl
128.28 (ortho-ArC), 131.23 (meta-ArC), 131.90 (para-ArC).
NMR, CDCl , d: 33.26 ppm. Anal. Calc. for C48
4.34; H, 3.10; O, 9.84. Found: C, 45.01; H, 3.25; O, 9.31%.
3
), d (ppm): 7.34 (8H, m, Ph), 7.44 (4H, t, Ph, JH–H = 6.52 Hz),
1
3
3
, d (ppm):
3
1
P
3
4 8 4
H40Ag O P : C,
4
À1
Selected IR data m/cm : 3077(m), 174 (s), 1120(s), 689 (s), 519 (s).
2.2. Preparation of Ph
2 3
P(O)N(H)CMe , (L1)
In a Schlenk tube, t-butylamine (0.332 g, 4.53 mmol) was added
2.5. Crystallography
to diethyl ether (30 mL) with stirring. The solution was immersed
into a dry ice/acetone bath at À78 °C and n-BuLi (2.84 mL, 1.6 M,
Crystals were mounted on glass fibers with epoxy resin, and all
geometric and intensity data were collected on a Bruker APEXII
CCD diffractometer equipped with graphite monochromated Mo
4
.54 mmol) was added drop-wise and stirred for 20 min.
Chlorodiphenylphosphine (0.974 g, 4.415 mmol) in diethyl ether
40 mL) was added slowly to the lithiated solution and stirred for
0 min. The reaction was gradually warmed to room temperature
(
2
Ka radiation (k = 0.71073 Å). The data reduction was carried out
with the SAINT-Plus software [32]. The SADABS program was used to
apply an empirical absorption correction [33]. All structures were
solved by direct methods and refined by full-matrix least-squares
and stirred for 20 min. The solvent volume was reduced and the
LiCl by-product was filtered off using a Büchner apparatus under
vacuum (presumably aerial oxidation at the P atom occurred dur-
ing this step). The filtrate was pumped down under reduced pres-
sure which resulted in a white solid. Yield: 0.826 g, 70%; Melting
2
on F with SHELXTL software package [34], found in SHELXTL/PC version
5.10 [35]. A complete listing of crystallographic data and parame-
ters are reported in Table 5.

V. Moodley et al. / Polyhedron 99 (2015) 87–95
89
3
. Results and discussion
.1. Ph P(O)N(H)CMe , L1
The ligand L1 was isolated as the aerially oxidized product of
yields a root mean square value of 1.84, which illustrates the large
difference in the orientation of the molecules within their respec-
tive unit cells. Further expansion along the hydrogen bonding con-
tacts of both L1 and its polymorph revealed that the packing of
both molecules differ, ie L1 adopts a zig-zag orientation while the
other polymorph adopts a closed circular orientation, see Fig. 2.
The solution structure of L1 shows a single peak in the 31P NMR
3
2
3
(
C
6
H
H
5
)
)
2
PNH-t-C
PNH-t-C
4
H
H
9
in 70% yield, see Scheme 1. The precursor
was in turn prepared from the reaction
(
C
6
5
2
4
9
between deprotonated tert-butylamine and diphenylchlorophos-
phine. The solid-state structure is a different polymorph from
one previously reported [36] which contains three molecules in
the asymmetric unit while the structure in the present study con-
tains only two. The molecular structure of L1, shown in dimeric
form and assembled through hydrogen bonds, is shown in Fig. 1.
The spatial difference between L1 and its known polymorph can
be observed through the overlay between the two molecules which
spectrum at 19.51 ppm. The infrared spectrum shows a strong
À1
band at 1175 cm
assigned to a m(P–O) stretching vibration.
Initially, it was assumed that the starting chlorodiphenylphosphine
3
1
was oxidised, but this was shown to be pure by P NMR, hence
oxidation either occurred aerially during the synthesis procedure,
but we suspect more likely during crystal growing manipulations
because all subsequent spectroscopies and elemental analysis were
determined from the obtained microcrystalline materials.
Scheme 1. Formation of N-tert-butyl-diphenylphosphinic amide ligand (L1), [Ag(CF
O)OPPh }{O PPh }], (2).
3
SO
3
)(OPPh
2
N(H)CMe
3 2
) }{Ag(OPPh
2
N(H)CMe
3 2
) }]SO
3
CF
3
2
(1), and [Ag {(l-
2
2
2

9
0
V. Moodley et al. / Polyhedron 99 (2015) 87–95
Fig. 1. Ligand L1 shown as dimer with atom labeling. The displacement ellipsoids are shown at the 50% probability level.
bonding parameters, see Table 2. The geometry of each P atom
can be described as a distorted tetrahedron as seen by angles
O(1)–P(1)–C(1) and O(1)–P(1)–N(1) as 109.51(5)° and 115.29(5)°,
respectively, around the P(1) center, and O(2)–P(2)–C(23) and
O(2)–P(2)–N(2) as 108.77(5)° and 117.15(5)°, respectively, around
P(2). The P@O bond lengths for the two molecules are 1.4900(8)
and 1.4911(9) Å respectively, and is in good agreement with the
literature values of the similar compounds [36]. The P–N and P–C
bond distances are comparable to similar compounds from litera-
ture [36–38].
3 3 2 3 2 2 3 2 3 3
3.2. [Ag(CF SO ){OPPh N(H)CMe } {Ag(OPPh N(H)CMe ) ]SO CF , (1)
The reaction between [OP(C
6 5 2 4 9
H ) (NH-tert-C H )] (L1) and
AgSO CF in THF led to the formation of a novel dinuclear
3
3
silver(I) complex and consists of a ligand unsupported weak
AgÁ Á ÁAg interactions coordinating through two O donor atoms from
the two separate silver units (A and B) and with no coordination
Fig. 2. (a) Overlay of previously reported polymorph [36] and L1, (b) closed circular
orientation (left) compared with zig-zag orientation (right) for L1. Hydrogen
bonding interactions dictate both polymorphic structures.
Table 2
Selected bond lengths (Å) and angles (°) for L1.
N(1)–P(1)
N(1)–H(9)
N(2)–P(2)
N(2)–H(2A)
P(1)–O(1)
P(2)–O(2)
C(23)–P(2)
C(13)–N(1)
C(7)–P(1)
C(1)–P(1)
1.6434(10)
0.8800
1.6357(10)
0.8800
1.4900(8)
1.4911(9)
1.8080(12)
1.4898(14)
1.8073(12)
1.8112(11)
P(2)–N(2)–H(2A)
O(1)–P(1)–N(1)
O(1)–P(1)–C(7)
N(1)–P(1)–C(7)
O(1)–P(1)–C(1)
N(1)–P(1)–C(1)
C(7)–P(1)–C(1)
O(2)–P(2)–N(2)
O(2)–P(2)–C(17)
N(2)–P(2)–C(17)
O(2)–P(2)–C(23)
N(2)–P(2)–C(23)
C(17)–P(2)–C(23)
C(29)–N(2)–P(2)
C(13)–N(1)–P(1)
C(13)–N(1)–H(1)
P(1)–N(1)–H(1)
N(1)–C(13)–C(14)
N(1)–C(13)–C(15)
C(2)–C(1)–P(1)
C(6)–C(1)–P(1)
115.5
The solid-state structure crystallized in a triclinic space group
115.29(5)
112.71(5)
103.33(5)
109.51(5)
109.81(5)
105.65(5)
117.15(5)
112.96(5)
101.05(5)
108.77(5)
108.23(5)
108.18(5)
128.98(8)
126.99(7)
116.5
P1 and contains two molecules in the asymmetric unit linked
together by hydrogen bonding, with the unit cell containing four
ligand molecules. In L1, the two asymmetric units are assembled
through the N(2)–H(2A)Á Á ÁO(1) hydrogen bonding interaction, in
the structure, the dimeric units are in turn held together by a net-
work of weak N(1)–H(1)Á Á ÁO(2) interactions, see Fig. 1 and Table 1.
The two molecules within the asymmetric unit interact via both
intra- and intermolecular hydrogen bonding interactions. The
two molecules in the asymmetric unit have virtually the same
Table 1
Hydrogen-bonding interactions.
116.5
105.96(9)
111.80(9)
119.63(9)
120.77(9)
D–HÁ Á ÁA (Å)
D–H (Å)
HÁ Á ÁA (Å)
DÁ Á ÁA (Å)
D–HÁ Á ÁA (°)
N(2)–H(2A)Á Á ÁO(1)
N(1)–H(1)Á Á ÁO(2)
0.88
0.88
2.03
2.28
2.8891 (13)
2.8932 (13)
172
127

V. Moodley et al. / Polyhedron 99 (2015) 87–95
91
Fig. 3. Complex 1 showing the atom labeling. The displacement ellipsoids are shown at the 50% probability level. Hydrogen atoms are excluded for clarity.
Table 3
Selected bond lengths (Å) and angles (°) for complex 1.
Ag(1)–Ag(2)
O(5)–Ag(2)
O(5)–S(1)
O(4)–Ag(2)
O(4)–P(4)
O(3)–Ag(2)
O(3)–P(3)
O(2)–Ag(1)
O(2)–P(2)
O(1)–Ag(1)
O(1)–P(1)
N(4)–P(4)
N(3)–P(3)
N(2)–P(2)
N(1)–P(1)
C(1)–P(1)
2.8979(3)
2.370(2)
1.449(2)
O(5)–Ag(2)–Ag(1)
O(4)–Ag(2)–Ag(1)
O(3)–Ag(2)–Ag(1)
O(4)–Ag(2)–O(5)
O(3)–Ag(2)–O(5)
O(3)–Ag(2)–O(4)
O(2)–Ag(1)–Ag(2)
O(1)–Ag(1)–Ag(2)
O(1)–Ag(1)–O(2)
C(7)–P(1)–C(1)
N(1)–P(1)–C(1)
O(1)–P(1)–C(1)
N(1)–P(1)–C(7)
O(1)–P(1)–C(7)
O(1)–P(1)–N(1)
S(1)–O(5)–Ag(2)
P(4)–O(4)–Ag(2)
P(3)–O(3)–Ag(2)
P(2)–O(2)–Ag(1)
P(1)–O(1)–Ag(1)
174.67(5)
66.89(4)
63.11(4)
107.77(7)
122.20(7)
129.68(6)
85.82(5)
2.2475(18)
1.5107(18)
2.2472(18)
1.5115(18)
2.1011(19)
1.5091(18)
2.0900(18)
1.5076(18)
1.648(2)
1.655(2)
1.633(2)
1.630(2)
1.802(2)
94.19(5)
179.56(8)
108.74(10)
110.20(11)
105.14(11)
103.71(10)
109.71(11)
119.09(11)
150.98(14)
110.16(9)
107.33(9)
118.24(11)
122.56(11)
through the N atom. Further, silver unit A contains a 3-coordinate
Ag(I) center, bent significantly from a linear geometry due to inter-
action from the triflate O donor atom, whilst unit B remained
Fig. 4. Packing diagram of 1 seen along the b axis.

9
2
V. Moodley et al. / Polyhedron 99 (2015) 87–95
Fig. 5. Asymmetric unit of complex 2 showing atom labeling. The displacement ellipsoids are shown at the 50% probability level.
Table 4
Selected Bond lengths (Å) and angles (°) for complex 2.
Ag(1)–Ag(2)
Ag(1)–O(2)
Ag(1)–O(3)
Ag(1)–O(4)c
Ag(1)–O(3)d
Ag(2)–O(2)
Ag(2)–O(4)
Ag(2)–O(1)a
Ag(2)–O(3)c
P(1)–O(1)
3.1596(2)
2.2274(13)
2.5133(13)
2.3343(13)
2.3418(12)
2.3962(13)
2.3349(13)
2.2058(14)
2.5044(13)
1.4982(13)
1.5120(13)
1.8010(18)
1.807(2)
O(3)–Ag(1)–Ag(2)
Ag(1)–Ag(2)–O(1)
Ag(1)–O(2)–Ag(2)
O(3)–Ag(1)–O(4)c
O(3)–Ag(1)–O(3)d
O(4)c–Ag(1)–O(3)d
O(3)–P(2)–C(19)
C(13)–P(2)–C(19)
O(4)–P(2)–C(19)
O(3)–P(2)–O(4)
171.77(3)
142.54(4)
86.13(5)
83.09(4)
87.63(4)
100.93(4)
108.95(8)
108.13(8)
107.75(8)
115.90(7)
118.25(8)
P(1)–O(2)
P(1)–C(1)
P(1)–C(7)
O(1)–P(1)–O(2)
P(2)–O(3)
P(2)–O(4)
P(2)–C(13)
P(2)–C(19)
1.5144(13)
1.5178(13)
1.8010(18)
1.802(2)
Fig. 6. Complex 2 seen along the (a) a axis (b) c axis.
previously analysed data. The solution structures of 1 by both 1H
3
1
and P NMR shows only a very slight shift when compared to
the free L1 ligand, suggesting the P@O–M dative coordinative bond
is weak. The infrared spectrum of complex 1 showed distinct bands
À1
essentially 2-coordinate and linear, see Scheme 1. Note that in the
preparation method a 1:1 M ratio was initially used in an attempt
to form metallacyclic neutral dinuclear silver(I) complex with an
at 3181 and 1172 cm , corresponding to M–O and P–O vibrational
stretches, respectively.
Complex 1 crystallized in the monoclinic Cc space group. The
argentophilic Ag(I)Á Á ÁAg(I) interaction between the two Ag atoms
is 2.8979(3) Å which coincides with previously reported bond dis-
tances in the range 2.869(5)–2.981(5) Å [39–41] and is also well
below the sum of van der Waals radii of silver [42]. A number of
different Ag-O bond lengths can be discerned. The longest is the
Ag(2)–O(5) bond derived from the triflate O donor atom to the
Ag atom, measuring 2.370(2) Å and also impacts on the geometry
around the Ag(2) atom. By comparison, the distance between
Ag(1) and O(9), with no triflate interaction, is ca. 5.078 Å. The
geometry around the Ag(2) atom adopts a distorted trigonal planar
geometry as suggested by the O(3)–Ag(2)–O(4) at 129.69(6), O(4)–
Ag(2)–O(5) at 107.77(7) and O(3)–Ag(2)–O(5) at 122.20(8)° bond
angles, respectively. The shorter distance is between Ag(2)–O(3)
2 2 3 2
anionic bridging O–P–N ligand of the type [Ag (OPPh NCMe ) ],
following deprotonation with triflate. This was based on the
assumption that the N atom would be activated, either in proto-
nated or deprotonated form. Clearly the conditions demanded a
M:L ratio of 1:2 instead, completely bypassing any N donor coordi-
nation with the metal, and with triflate ions being retained in the
structure. This caused a significant reduction of overall yield (35%).
Given that Ag(I) can easily bind non-bulky N donor ligands, in
hindsight one may speculate that the N lone-pair electrons in this
case is sterically hindered by the combination of t-butyl group and
phenyl rings, preventing coordination. Knowing the more efficient
ratio to be 1:2, the experiment was repeated, affording a higher
yield (68%). The characterized material corresponded with

V. Moodley et al. / Polyhedron 99 (2015) 87–95
93
presumably arises from a significant positive charge located on
the silver atom, capable of drawing the lone pair electrons on the
O atoms very close and increasing the bond strength. The atoms
O(2)–Ag(1)–O(1) adopts an almost linear geometry with a bond
angle of 179.56(7)°. The molecular structure of complex 1 is shown
in Fig. 3. The two silver units that make up the dinuclear molecule
sit at approximate right angles to each other, as shown in the pack-
ing diagram in Fig. 4. Selected bond lengths and angles are shown
in Table 3.
In addition, there are four N atoms within the complex that are
not coordinated. These N donor atoms could further react to poten-
tially form a supramolecular heterometallic system.
2 2 2 2
3.3. [Ag {(l-O)OPPh }{O PPh }], (2)
The reaction between t-butylamine, DMAP, triethylamine and
chlorodiphenylphosphine, in an attempt to form an aminophosphi-
nate led instead to further oxidation yielding a diphenylphosphinic
acid ligand. Further reaction with Ag(SO
THF led to the formation of a novel coordination polymer of
silver(I) with bridging ( -O) and non-bridging O atoms, [Ag {(
O)OPPh }{O PPh }], (2), as shown in Scheme 1. An after-the-fact
3 3
CF ) (molar ratio 1:1) in
l
2
l-
Fig. 7. Packing diagram of complex 2 seen along the bc plane.
2
2
2
investigation showed that synthesis of pure diphenylphosphinic
acid independently, and subsequent reaction with Ag(SO CF ) also
and Ag(2)–O(4) atoms at equidistant bond lengths of 2.2472(19)
and 2.2475(18) Å, respectively. The bond lengths here are clearly
influenced by the presence of the triflate ion interacting with the
Ag atom, presumably drawing positive charge away from the Ag
atom. It is worthy to note that the P(1)–O(1), P(2)–O(2), P(4)–
O(4) P(3)–O(3) bond lengths all fall within a narrow range of
between 1.507 and 1.511 Å, which is longer than the free ligand
at 1.49 Å, but not to the extent that it can fully account for the
Ag–O bond length differences. The shortest Ag–O bond lengths
are found for Ag(1)–O(1) and Ag(1)–O(2) at distances of
3
3
3
1
leads to complex 2, as confirmed by P NMR analysis. The solution
3
1
structure of 2, based on the P NMR spectrum, showed a single
peak at 33.26 ppm suggesting a fully oxidized 4-coordinate P atom,
thus negating any possible M–P bonding. The infrared spectrum of
À1
complex 2 showed distinct bands at 3077 and 1175 cm assigned
to
m(M–O) and
m(P–O) stretching vibrations, respectively.
In the solid-state, complex 2 crystallized in the monoclinic
space group P2 /c. Complex 2 is a coordination polymer showing
1
argentophilic Ag(I)Á Á ÁAg(I) interactions as well as a combination
2
.0900(18) and 2.101(2) Å, respectively. This short distance
of dative- and covalent bonding to four adjacent oxygen atoms.
Table 5
Crystal data and structure refinement of L1 and complexes 1 and 2.
L1
1
2
Empirical formula
Formula weight
T (K)
C
16
H
20NOP
C
66
H
76Ag
2
F
6
N
4
O
10
P
4
S
2
C
24 2 4 2
H20Ag O P
273.30
173(2)
0.71073
1603.05
173(2)
0.71073
650.08
150
0.71073
k (Å)
Crystal system
Space group
a (Å)
b (Å)
c (Å)
triclinic
P1ꢀ
9.9212(2)
10.9651(2)
monoclinic
Cc
monoclinic
P21/c
5.8703(2)
23.9827(7)
15.6932(5)
90
92.9530(10)
90
2206.44(12)
4
17.8630(3)
22.8841(4)
17.3304(3)
90
94.7690(10)
90
7059.8(2)
4
1.508
13.9669(3)
a
(°)
b (°)
(°)
89.3440(10)
82.3230(10)
83.0590(10)
1494.75(5)
c
3
V (Å )
Z
4
3
Density (calculated) (Mg/m )
Absorption coefficient (mm
1.214
0.176
1.957
1.950
À1
)
0.779
F(000)
Crystal size (mm )
Theta range for data collection
Index ranges
584
3280.0
1280
3
0.27 Â 0.25 Â 0.21
1.87° to 28.31°
À13 6 h 6 13, À13 6 k 6 14,
À18 6 l 6 18
47,775
0.35 Â 0.34 Â 0.22
0.050 Â 0.050 Â 0.110
1.78° to 28.29°
1.55° to 28.70°
À23 6 h 6 23, À28 6 k 6 30,
À23 6 l 6 23
À7 6 h 6 7, À29 6 k 6 32,
À21 6 l 6 21
Reflections collected
84,418
24,811
Independent reflections (Rint
Absorption correction
Refinement method
)
7384 (0.0189)
Semi-empirical from equivalents
Full-matrix least-squares on F2
7384/0/349
17,258 (0.0238)
5688 (0.0256)
Semi-empirical from equivalents
Full-matrix least-squares on F2
17,258/2/860
Semi-empirical from equivalents
Full-matrix least-squares on F2
5688/0/289
Data/restraints/parameters
Goodness-of-fit (GOF) on F
2
1.040
1.039
1.928
Final R indices [I > 2
R indices (all data)
r(I)]
R
R
1
= 0.0331, wR
= 0.0388, wR
2
2
= 0.0856
= 0.0895
R
1
= 0.0277, wR
2
= 0.0839
= 0.0850
R
1
= 0.0228, wR
2
= 0.0458
2
= 0.0463
1
R1 = 0.0288, wR
2
R1 = 0.0277, wR
Largest difference peak and hole
0.633 and À0.741
0.997 and À0.606
0.573 and À0.640
À3
(
e Å
)

9
4
V. Moodley et al. / Polyhedron 99 (2015) 87–95
The ligand have two binding modes through the O atoms, namely
i) one oxygen atom binding to two silver(I) atoms and the other
bridging oxygen binding to a silver(I) atom of the next unit, and
ii) the alternate ligand binds two oxygen atoms to two silver(I)
References
(
[
1] (a) P. Pyykkö, Chem. Rev. 97 (1997) 597;
(
(
b) H. Schmidbaur, S. Cronje, B. Djordjevic, O. Schuster, Chem. Phys. 311
2005) 151;
(
atoms. A portion of the molecular structure within the asymmetric
unit is shown in Fig. 5.
The two distinct coordination modes within the complex can
be described as trimetallic triconnective and tetrametallic tetra-
(c) A.N. Khlobystov, A.J. Blake, N.R. Champness, D.A. Lemenovskii, A.G.
Majouga, N.V. Zyk, M. Schröder, Coord. Chem. Rev. 222 (2001) 155;
(
(
d) V.W.-W. Yam, K.K.-W. Lo, Chem. Soc. Rev. 28 (1999) 323;
e) X. Wang, J. Feng, J. Huang, J. Zhang, M. Pan, C.-Y. Su, CrystEngComm 12
(2010) 725.
connective. The former ligand has two distinct oxygen binding
[2] (a) P. Pyykkö, Angew. Chem., Int. Ed. 43 (2004) 4412;
(b) H. Schmidbaur, A. Schier, Chem. Soc. Rev. 41 (2012) 370.
2
modes, namely
jO and
j
O. This resulted in the non-symmetric
[
3] A. Bayler, A. Schier, G.A. Bowmaker, H. Schmidbaur, J. Am. Chem. Soc. 118
1996) 2006.
coordination mode observed, as seen in the elongated bond
(
2
1
lengths of P-
symmetric
j
O compared to P-
j
O. For the latter ligand, a
[4] L. Dobrzanska, H.G. Raubenheimer, L.J. Barbour, Chem. Commun. (2005) 5050.
[5] (a) Q.-M. Wang, T.C.W. Mak, J. Am. Chem. Soc. 123 (2001) 7594;
2
j O bonding is observed, shown by the equivalent bond
(
3
b) M.A. Omary, T.R. Webb, Z. Assefa, G.E. Shankle, H.H. Patterson, Inorg. Chem.
7 (1998) 1380;
(c) X. Liu, G.-C. Guo, M.-L. Fu, X.-H. Liu, M.-S. Wang, J.-S. Huang, Inorg. Chem.
5 (2006) 3679;
lengths of P(2)–O(3) and P(2)–O(4) at 1.5144(13) and 1.5178(13) Å,
respectively, see Fig. 5. The bond distance between P–O atoms
suggests delocalization between the O–P–O atoms because they
are intermediate between double- and single P–O bonds, ie
P(1)–O(1) and P(1)–O(2) has distances of 1.4982(13) and
4
(
(
d) M.A. Omary, H.H. Patterson, Inorg. Chem. 37 (1998) 1060;
e) C.J. Shorrock, B.-Y. Xue, P.B. Kim, R.J. Batchelor, B.O. Patrick, D.B. Leznoff,
Inorg. Chem. 41 (2002) 6743;
(
(
f) B. Liu, W. Chen, S. Jin, Organometallics 26 (2007) 3660;
g) A.A. Mohamed, L.M. Perez, J.P. Fackler, Inorg. Chim. Acta 358 (2005) 1657.
1
.5120(13) Å, respectively, see Table 4. The geometry around each
P atom is slightly distorted tetrahedral as observed from the bond
angles O(3)–P(2)–O(4) and O(1)–P(1)–O(2) at 115.90(7)° and
[
[
6] (a) C.-M. Che, M.-C. Tse, M.C.W. Chan, K.-K. Cheung, D.L. Phillips, K.-H. Leung, J.
Am. Chem. Soc. 122 (2000) 2464;
(
(
(
b) X.-C. Huang, J.-P. Zhang, X.-M. Chen, Cryst. Growth Des. 6 (2006) 1194;
c) G.-C. Guo, G.-D. Zhou, Q.-G. Wang, T.C.W. Mak, Angew. Chem., Int. Ed. 37
1998) 630;
1
18.25(8)°, respectively. The different bond lengths for
Ag(1)–O(3), Ag(2)–O(4), Ag(1)–O(2) and Ag(2)–O(2) from the phos-
phinic moiety, measuring 2.5134(13), 2.3349(13), 2.2274(13),
(d) G.-C. Guo, T.C.W. Mak, Angew. Chem., Int. Ed. 37 (1998) 3183;
(e) G.-C. Guo, G.-D. Zhou, T.C.W. Mak, J. Am. Chem. Soc. 121 (1999) 3136;
2
.3962(13) Å, respectively, impacts on the geometry around the
(
f) Q.-M. Wang, T.C.W. Mak, Inorg. Chem. 42 (2003) 1637.
7] (a) K. Singh, J.R. Long, P. Stavropoulos, J. Am. Chem. Soc. 119 (1997) 2942;
b) Y. Kimand, K.J. Seff, J. Am. Chem. Soc. 100 (1978) 175;
(c) M.L. Tong, X.M. Chen, B.H. Ye, L.N. Ji, Angew. Chem., Int. Ed. 38 (1999)
237;
Ag atoms which presumably leads to a coordination polymer
containing both bridging and non-bridging O atoms, see Fig. 6
and Fig. 7, showing portions of the crystal structure along different
axes and planes. Both Ag atoms are surrounded by O-donor atoms
(
2
(
(
d) O. Kristiansson, Inorg. Chem. 40 (2001) 5058;
e) Y. Zhou, W. Chen, D. Wang, Dalton Trans. (2008) 1444;
in
a (pseudo) 4-coordinate arrangement. The argentophilic
Ag(1)Á Á ÁAg(2) interaction is at a bond distance of 3.1596(2) Å.
(f) Y.-L. Wang, Q.-Y. Liu, L. Xu, CrystEngComm 10 (2008) 1667.
8] (a) D. Fenske, T. Langetepe, Angew. Chem., Int. Ed. 41 (2002) 300;
[
[
(
b) S. Canales, O. Crespo, M.C. Gimeno, P.G. Jones, A. Laguna, A. Silvestru, C.
Silvestru, Inorg. Chim. Acta 347 (2003) 16;
c) M.R. Bermejo, A.M. Gonzalez-Noya, R.M. Pedrido, M.J. Romero, M. Vazquez,
4
. Conclusions
(
Angew. Chem., Int. Ed. 44 (2005) 4182.
9] (a) C.W. Liu, H.-W. Chang, C.-S. Fang, B. Sarkar, J.-C. Wang, Chem. Commun. 46
(2010) 4571;
This study reports on a new polymorphic form for the ligand
Ph
as a result of hydrogen bonding. Treatment of the ligand with solid
AgSO CF formed a rare cationic dinuclear silver(I) complex of the
type [Ag(CF SO ){OPPh N(H)CMe {Ag(OPPh N(H)CMe }]SO CF
2 3
P(O)N(H)CMe , showing a dimeric association in the solid-state
(
b) J.-H. Liao, H.-W. Chang, Y.-J. Li, C.-S. Fang, B. Sarkar, W.E. van Zyl, C.W. Liu,
Dalton Trans. 43 (2014) 12380.
10] X.-L. Zhao, Q.-M. Wang, T.C.W. Mak, Chem. Eur. J. 11 (2005) 2094.
3
3
[
3
3
2
}
3 2
2
)
3 2
3
3
,
[11] C.W. Liu, P.-K. Liao, C.-S. Fang, J.-Y. Saillard, S. Kahlal, J.-C. Wang, Chem.
Commun. 47 (2011) 5831.
which contains a short ligand unsupported AgÁÁÁAg interaction bind-
ing through two P@O oxygen donor atoms rather than any of the
available N donor atoms. The two silver atoms have different
geometries caused by a triflate interaction with one silver atom.
Further oxidation of the ligand led to diphenylphosphinic acid,
[
12] (a) L. Hou, D. Li, Inorg. Chem. Commun. 8 (2005) 128;
b) D. Sun, N. Zhang, G.-G. Luo, Q.-J. Xu, R.-B. Huang, L.-S. Zheng, Polyhedron
9 (2010) 1842;
(c) A.-M. Stadler, N. Kyritsakas, G. Vaughan, J.-M. Lehn, Chem. Eur. J. 13 (2007)
9;
(
2
5
(
(
d) S. Wang, J.P. Fackler, T.F. Carlson, Organometallics 9 (1990) 1973;
e) M.J. Hannon, C.L. Painting, E.A. Plummer, L.J. Childs, N.W. Alcock, Chem.
which upon reaction with AgSO
nation polymer, [Ag {( -O)OPPh
3
CF
3
led to an unusual Ag(I) coordi-
PPh }] consisting of O-donor
l
2
}{O
2
2
n
Eur. J. 8 (2002) 2225;
f) J.-C. Jin, Y.-Y. Wang, W.-H. Zhang, A.S. Lermontov, E.K. Lermontova, Q.-Z.
2
(
atoms in a 4-coordinate arrangement around the Ag(I) center.
Shi, Dalton Trans. (2009) 10181.
[
[
13] (a) K. Xiong, M. Wu, Q. Zhang, W. Wei, M. Yang, F. Jiang, M. Hong, Chem.
Commun. (2009) 1840;
Acknowledgements
(
b) B.H. Hong, S.C. Bae, C.-W. Lee, S. Jeong, K.S. Kim, Science 294 (2001) 348.
14] (a) D. Sun, Z.H. Wei, C.F. Yang, D.F. Wang, N. Zhang, R.B. Huang, L.S. Zheng,
CrystEngComm 13 (2011) 1591;
WEvZ gratefully acknowledges financial support from the
University of KwaZulu-Natal and for X-ray diffractometer usage.
VM and MNP thank the National Research Foundation (NRF),
South Africa, for Innovative Grants.
(b) D. Sun, D.F. Wang, N. Zhang, F.J. Liu, H.J. Hao, R.B. Huang, L.S. Zheng, Dalton
Trans. 40 (2011) 5677;
(
c) D. Sun, Z.-H. Wei, D.-F. Wang, N. Zhang, R.-B. Huang, L.-S. Zheng, Cryst.
Growth Des. 11 (2011) 1427;
d) F.-J. Liu, D. Sun, H.-J. Hao, R.-B. Huang, L.-S. Zheng, Inorg, Chem. Commun.
5 (2012) 136.
15] B.-L. Fei, W.-Y. Sun, T.-A. Okamura, W.-X. Tang, N. Ueyama, New J. Chem. 25
2001) 210.
16] (a) D. Sun, R. Cao, J. Weng, M. Hong, Y. Liang, J. Chem. Soc., Dalton Trans.
(
1
Appendix A. Supplementary Data
[
[
(
Crystallographic data have been deposited with the Cambridge
Crystallographic Data Centre (CCDC) as supplementary material
under deposition nos. CCDC 1060026, 1060027
Copies of this material can be obtained free of charge from: The
Director, CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK Fax:
(
2002) 291;
(
b) X. Li, Y. Wang, Y. Li, Y. Gou, Q. Wang, Anorg. Allg. Chem. 640 (2014) 423;
&
1060029.
(c) G. Yang, P. Baran, A.R. Martínez, R.G. Raptis, Cryst. Growth Des. 13 (2013)
264;
(
d) B. Coyle, M. McCann, K. Kavanagh, M. Devereux, V. McKee, N. Kayal, D.
Egan, C. Deegan, G.J. Finn, J. Inorg. Biochem. 98 (2004) 1361.
17] D. Sun, G.-G. Luo, N. Zhang, R.-B. Huang, L.-S. Zheng, Chem. Commun. 47
(2011) 1461.
+44(1233)336 033, email deposit@ccdc.cam.ac.uk or CCDC via
[
www.ccdc.cam.ac.uk/data-request/cif.

V. Moodley et al. / Polyhedron 99 (2015) 87–95
95
[
[
[
[
18] K. Katagiri, T. Sakai, M. Hishikawa, H. Masu, M. Tominaga, K. Yamaguchi, I.
Azumaya, Cryst. Growth Des. 14 (2014) 199.
19] D.A. Couch, S.D. Robinson, J.N. Wingfield, J. Chem. Soc., Dalton Trans. (1974)
(h) D.B.G. Williams, T. Traut, F.H. Kriel, W.E. van Zyl, Inorg. Chem. Commun. 10
(2007) 538;
(i) S.V. Sithole, R.J. Staples, W.E. van Zyl, Inorg. Chem. Commun. 15 (2012)
216;
(j) P.-K. Liao, W.-S. Chang, Y.-C. Lee, W.E. van Zyl, C.W. Liu, Dalton Trans. 42
(2013) 5258;
(k) M.N. Pillay, B. Omondi, R.J. Staples, W.E. van Zyl, CrystEngComm 15 (2013)
4417;
1
309.
20] J.D.E.T. Wilton-Ely, A. Schier, H. Schmidbaur, J. Chem. Soc., Dalton Trans. (2001)
647.
21] Y.-M. Li, M. Sun, H.-Li Wang, Q.-P. Tian, S.-D. Yang, Angew. Chem., Int. Ed. 52
2013) 3972.
3
(
[
[
[
[
[
22] S. Miao, W.-R. Yao, D.-S. Guo, Q.-F. Zhang, J. Mol. Struct. 660 (2003) 159.
23] Y.-P. Xie, T.C.W. Mak, Dalton Trans. 42 (2013) 12869.
24] C.-W. Yeh, K.-H. Chang, C.-Y. Hu, W. Hsu, J.-D. Chen, Polyhedron 31 (2012) 657.
25] J. Guo, W.-K. Wong, W.-Y. Wong, Polyhedron 24 (2005) 927.
(l) Y.-C. Lee, Y.-R. Lin, B.-Y. Liou, J.-H. Liao, N.K. Gusarova, B.A. Trofimov, W.E.
van Zyl, C.W. Liu, Dalton Trans. 43 (2014) 663;
(m) R.S. Dhayal, J.-H. Liao, S. Kahlal, X. Wang, Y.-C. Liu, M.-H. Chiang, W.E. van
Zyl, J.-Y. Saillard, C.W. Liu, Chem. Eur. J. 21 (2015) 8369.
[32] SAINT V4.043: Software for the CCD Detector System, Bruker Analytical X-ray
System, Madison, WI, 1995.
26] A. Panneerselvam, M.A. Malik, P. O’Brien, M. Helliwell, Chem. Vap. Deposition
1
5 (2009) 57.
[
[
[
[
[
27] H.H. Sisler, N.L. Smith, J. Org. Chem. 26 (1961) 611.
[33] G.M. Sheldrick, SADABS, University of Gottingen, Gottingen, Germany, 1996.
[34] G.M. Sheldrick, SHELXL-97. Program for the Refinement of Crystal Structure,
University of Göttingen, Göttingen, Germany, 1997.
[35] SHELXL 5.10 (PC version). Program Library for Structure Solution and Molecular
Graphics, Bruker analytical X-ray System, Madison, WI, 1998.
[36] W.S. Han, S.W. Lee, J. Korean Chem. Soc. 45 (2001) 264.
[37] S. Priya, M.S. Balakrishna, S.M. Mobin, Polyhedron 24 (2005) 1641.
[38] H.H. Kinfe, A. Hamese, T. Hughes, B. Omondi, Acta Crystallogr. E67 (2011)
o3392.
[39] S. Priya, M.S. Balakrishna, J.T. Mague, S.M. Mobin, Inorg. Chem. 42 (2003) 1272.
[40] B. Li, S.-Q. Zang, H.-Y. Li, Y.-J. Wu, T.C.W. Mak, J. Organomet. Chem. 708–709
(2012) 112.
[41] H.L. Zhu, X.M. Zhang, X.Y. Liu, X.J. Wang, G.F. Liu, A. Usman, H.K. Fun, Inorg.
Chem. Commun. (2003) 1113.
28] N.L. Smith, H.H. Sisler, J. Org. Chem. 26 (1961) 5145.
29] T.A. Modro, M.A. Lawry, E. Murphy, J. Org. Chem. 43 (1978) 5000.
30] V.K. Jain, R.J. Butcher, Polyhedron 17 (1998) 1317.
31] (a) W.E. van Zyl, J.D. Woollins, Coord. Chem. Rev. 257 (2013) 718;
(
(
(
(
(
b) W.E. van Zyl, Comments Inorg. Chem. 31 (2010) 13;
c) W.E. van Zyl, R.J. Staples, J.P. Fackler, Inorg. Chem. Commun. 1 (1998) 51;
d) W.E. van Zyl, J.M. López-de-Luzuriaga, J.P. Fackler, J. Mol. Struct. 516
2000) 99;
e) W.E. van Zyl, J.P. Fackler, Phosphorus, Sulfur Silicon Relat. Elem. 167 (2000)
1
(
7
(
17;
f) W.E. van Zyl, J.M. López-de-Luzuriaga, J.P. Fackler, R.J. Staples, Can. J. Chem.
9 (2001) 896;
g) W.E. van Zyl, J.M. López-de-Luzuriaga, A.A. Mohamed, R.J. Staples, J.P.
Fackler, Inorg. Chem. 41 (2002) 4579;
[42] S.-Z. Hu, Z.-H. Zhou, B.E. Robertson, Z. Kristallogr. 224 (2009) 375.