2-Thia-1,3,5-triaza-7-phosphaadamantane-2,2-dioxide Revisited: Computational and experimental studies of a neglected phosphine

Article abstract of DOI:10.1021/om100579e

The cage-phosphine 2-thia-1,3,5-triaza-7-phosphaadamantane-2,2-dioxide (PASO₂) was reacted with various transition metal precursors to give the complexes cis-[Mo(CO)₄(PASO₂)₂], [AuCl(PASO₂)], cis-[PtCl₂(PASO₂)₂], [Ru(η⁶-p-cym)Cl₂(PASO₂)], [Rh(η⁵-C₅Me₅)Cl₂(PASO ₂)], and [Rh(η⁵-C₅Me₅) Cl(PASO₂)₂]⁺ as well as the cyclometalated palladium(II) complexes [PdCl{κC,N-C₆H₄C(Ph)NCH ₂CO₂Et}(PASO₂)] and [PdCl(κC,N-1,8-C ₁₀H₆NMe₂)(PASO₂)]. The compounds were characterized by spectroscopic methods and several examples by single-crystal X-ray diffraction. The stereoelectronic properties of PASO ₂ were determined by computational methods and were compared with those of other phosphines, in particular 1,3,5-triaza-7-phosphaadamantane.

Full text of DOI:10.1021/om100579e

3922 Organometallics 2010, 29, 3922–3929
DOI: 10.1021/om100579e
2-Thia-1,3,5-triaza-7-phosphaadamantane-2,2-dioxide Revisited:
Computational and Experimental Studies of a Neglected Phosphine
Michelle Sternberg,† Cherumuttathu H. Suresh,‡ and Fabian Mohr*,†
†
€
Fachbereich C, Anorganische Chemie, Bergische Universitat Wuppertal, 42119 Wuppertal, Germany, and
‡Computational Modeling and Simulation Section, National Institute for Interdisciplinary Science and
Technology (CSIR), Trivandrum 695 019, India
Received June 12, 2010
The cage-phosphine 2-thia-1,3,5-triaza-7-phosphaadamantane-2,2-dioxide (PASO2) was reacted with
various transition metal precursors to give the complexes cis-[Mo(CO)4(PASO2)2], [AuCl(PASO2)],
cis-[PtCl2(PASO2)2], [Ru(η6-p-cym)Cl2(PASO2)], [Rh(η5-C5Me5)Cl2(PASO2)], and [Rh(η5-C5Me5)Cl-
(PASO2)2]þ as well as the cyclometalated palladium(II) complexes [PdCl{κC,N-C6H4C(Ph)NCH2CO2Et}-
(PASO2)] and [PdCl(κC,N-1,8-C10H6NMe2)(PASO2)]. The compounds were characterized by spectro-
scopic methods and several examples by single-crystal X-ray diffraction. The stereoelectronic properties
of PASO2 were determined by computational methods and were compared with those of other
phosphines, in particular 1,3,5-triaza-7-phosphaadamantane.
Introduction
Daigle in 1974,3 and its crystal structure was published two
years later.13 Since then, only one paper describing the
tungsten carbonyl complex, [W(CO)5(PASO2)], as well as
some reactivity studies has appeared.14 Although PASO2 is
not soluble in water, its coordination chemistry nevertheless
warrants more exploration. Given our interest in precious
metal complexes containing PTA and their applications,15-20
we report here an extended chemical and computational
study of the coordination chemistry of PASO2.
Development of the coordination chemistry of the steri-
cally small, water-soluble cage phosphine 1,3,5-triaza-7-
phosphaadamantane (abbreviated in the literature as both
PTA and TPA) has seen rapid growth in the past 15 years,1,2
although the compound itself has been known since 1974.3,4
More recently, a variety of modified analogues of PTA and their
metal complexes have been reported including N-alkylated
compounds,5-8 open-cage derivatives,7,9,10 “upper-rim”-
functionalized derivatives derived from the lithium salt,11
and “lower-rim” analogues,12 shown in Chart 1.
Results and Discussion
One analogue of PTA, 2-thia-1,3,5-triaza-7-phosphaada-
mantane-2,2-dioxide (PASO2), in which one NCH2N methy-
lene bridge is replaced by an SO2 group, has been almost
entirely neglected. The compound was first reported by
In order to get a better understanding of the electronic
properties of PASO2, we initially prepared the molybdenum
carbonyl complex cis-[Mo(CO)4(PASO2)2] (1), which was
readily accessible from the reaction of cis-[Mo(CO)4(pip)2]
(pip = piperidine) with two equivalents of PASO2, and
examined its IR spectrum. The solid-state IR spectrum of 1
reveals four bands for the CO stretching frequencies, as
expected for a C2v-symmetric cis-[M(CO)4L2]-type complex.
For comparison, we also measured the solid-state IR spec-
trum of the PTA analogue, since in the literature only
*To whom correspondence should be addressed. E-mail: fmohr@
uni-wuppertal.de.
(1) Phillips, A. D.; Gonsalvi, L.; Romerosa, A.; Vizza, F.; Peruzzini,
M. Coord. Chem. Rev. 2004, 248, 955.
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Rev. 2010, 254, 555.
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Chem. 1974, 11, 407.
(4) Fluck, E.; Forster, J. E. Chem. Zeitung 1975, 99, 246.
(5) Daigle, D. J.; Pepperman, A. B., Jr. J. Heterocycl. Chem. 1975,
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pubs.acs.org/Organometallics
Published on Web 08/12/2010
2010 American Chemical Society

Article
Organometallics, Vol. 29, No. 17, 2010 3923
Chart 1
Table 1. Summary of the Computed Steroelectronic Properties
of PASO2 and PTA
Vmin(PR3), SeffþEeff
,
Vmin(ONIOM_PR3),
Seff
,
Eeff,
kcal/mol
kcal/mol
kcal/mol
kcal/mol kcal/mol
PASO2
PTA
-20.68
-33.69
-7.54
5.48
-36.36
-30.62
8.14
3.07
-15.68
2.40
Table 2. Comparison of 31P NMR Data for PASO2 and
PTA Complexes
31P chemical shift
(recorded in dmso-d6)
compound
PASO2
PTA
[AuCl(PASO2)]
[AuCl(PTA)]
cis-[PtCl2(PASO2)2]
cis-[PtCl2(PTA)2]
cis-[Pt(N3)2(PASO2)2]
cis-[Pt(N3)2(PTA)2]28
ΔPa
-116.9
0.0
0.0
-104.1
-56.6
60.3
52.0
52.9
51.1
48.0
45.0
-52.1
-64.0 (JP-Pt = 3387 Hz)
-53.0 (JP-Pt = 3309 Hz)
-68.9 (JP-Pt = 3257 Hz)
-59.1 (JP-Pt = 3140 Hz)
aΔP is defined here as the chemical shift difference between the free
phosphine and the coordinated phosphine.
solution IR data were available.21 The results show that, in
particular, the positions of the A1 band at 2033 cm-1
(PASO2) and 2014 cm-1 (PTA) are significantly different
in the two complexes, indicating that despite their apparent
structural similarity, the electronic properties of PTA and
PASO2 are quite different. This observation is in marked
contrast to the previous paper comparing IR data of the
W-complexes [W(CO)5L] (L=PTA, PASO2), in which no
significant CO band shifts were observed, leading the
authors to conclude that the two phosphines are quite similar
in electronic character.14 On the basis of our experimental
data we can qualitatively conclude that PASO2 is a stronger
π-acid (π-acceptor) than PTA.
To confirm this finding, we carried out a computational
study on the two phosphines using the total electronic (Eeff)
and steric effects (Seff) methodology developed by Suresh
and co-workers.22 The results are shown in Table 2, where
the Vmin values correspond to the molecular electrostatic
potential minimum at the lone pair region of the phos-
phorus.23,24 The Vmin(PASO2) is determined using the
B3LYP/6-31G(d,p) method, while Vmin(ONIOM_PASO2)
is calculated using the ONIOM(B3LYP/6-31G(d,p):UFF)
hybrid QM-MM method.25,26 The computational data indeed
Figure 1. Molecular electrostatic potential isosurface map of
value -18.83 kcal/mol for the PASO2 ligand. (a) B3LYP/6-
31G(d,p) result. (b) ONIOM(B3LYP/6-31G(d,p):UFF) result.
In (b), the stick representation is used to show the UFF region,
which is linked to the QM region via H atoms. The value of Vmin
is also indicated with a black dot.
(21) Darensbourg, D. J.; Kump, R. L. Inorg. Chem. 1978, 17, 2680.
(22) Mathew, J.; Thomas, T.; Suresh, C. H. Inorg. Chem. 2007, 47,
10800.
confirm the significantly different stereoelectronic properties of
the two phosphines. The data show that PASO2 combines a
high electron-donating steric effect with a high withdrawing
electronic effect. This high electron-withdrawing nature origi-
nates from the SO2 unit, which can clearly been seen from the
molecular electrostatic potential isosurface map given in Figure 1.
PTA, in contrast, shows a much weaker electron-donating
steric effect and is weakly electron donating, as can be seen
from the plot in Figure 2, where the stereoelectronic profile of
typical phosphine ligands and two phosphate ligands are also
depicted for comparison.22 The electron-withdrawing power of
the PASO2 ligand (Eeff =-15.68 kcal/mol) is comparable to
that of phosphate ligands QIVLOW (Eeff=-15.20 kcal/mol)
and HAZXOV (Eeff=-12.92 kcal/mol), whereas its electron-
donating steric effect (Seff = 8.14 kcal/mol) is significantly
higher than these ligands (Seff is 3.30 kcal/mol QIVLOW and
-3.12 kcal/mol for HAZXOV).22 The steric effect of PASO2 is
as strong as the relatively bulky P(iPr)3 ligand.
(23) Suresh, C. H. Inorg. Chem. 2006, 45, 4982.
(24) Suresh, C. H.; Koga, N. Inorg. Chem. 2002, 41, 1573.
(25) Vreven, T.; Morokuma, K. J. Comput. Chem. 2000, 21, 1419.
(26) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A.; Vreven, T.; Kudin,
K. N.; Burant, J. C.; Millam, J. M.; Yengar, S. S.; Tomasi, J.; Barone,
V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson,
G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.;
Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai,
H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken,
V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev,
O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala,
P. Y.; Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.;
Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas,
O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.;
Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov,
B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.;
Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.;
Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.;
Gonzalez, C.; Pople, J. A. Gaussian 03, Revision E.01; Gaussian, Inc.,
2004.

3924 Organometallics, Vol. 29, No. 17, 2010
Sternberg et al.
Scheme 1
containing aliphatic and aromatic substituents does not lead
to an improved solubility in organic solvents.
The compounds were however soluble enough in dmso to
allow characterization by NMR spectroscopy. The 1H NMR
spectra of compounds 2-4 show, in addition to other ligand
signals, two AB quartets and one singlet resonance for the
PASO2 protons. The singlet is due to the PCH2N group that
lies in the plane bisecting the SO2 unit, while the AB system
arises from inequivalent axial and equatorial methylene
group protons. Similarly to what has been observed in many
metal complexes containing PTA, the PCH2N protons in
PASO2 metal complexes do not display coupling with the
phosphorus atom. We could unambiguously assign the
PCH2N and NCH2N protons by using 13C-1H 2D NMR
spectroscopy (see Experimental Section for details). The 31P
NMR spectra of complexes 2-4 show singlet resonances at
around -60 ppm, which are shifted by ca. 60 ppm from the
resonance of free PASO2 (-116.9 ppm). In the case of the Pt
complexes 3 and 4, Pt satellites with coupling constants of ca.
3300 Hz are also observed. The magnitude of these Pt-P
coupling constants is consistent with a cis geometry about
the platinum atom. This has been confirmed by an X-ray
structure of the PTA derivative cis-[Pt(N3)2(PTA)2], which
shows a very similar Pt-P coupling constant of 3140 Hz in its
31P NMR spectrum.27
Figure 2. Stereoelectronic plot of phosphine ligands. Data
(except those for PASO2) are taken from ref 22.
Gold(I) and Platinum(II) Complexes. PASO2 readily dis-
places the weakly coordinating ligands in [AuCl(tht)] (tht=
tetrahydrothiophene) and cis-[PtCl2(cod)] (cod=1,5-cyclo-
octadiene) to give [AuCl(PASO2)] (2) and cis-[PtCl2-
(PASO2)2] (3), respectively, in high yields. Both complexes
are insoluble in water and poorly soluble in most solvents
including dmso and dmf. In an attempt to improve solubi-
lity, we prepared several derivatives by anion exchange of the
chloride ligands. The thiolato gold(I) complexes [Au(SR)-
(PASO2)] (R=3,5-dimethylpyrimidyl, 2a) and [Au(S2CNR2)-
(PASO2)] (R=Et, 2b; Bz, 2c) were prepared by treatment of 2
with the sodium salt of 3,5-dimethylpyrimidinethiol or sodium
diethyl- and dibenzyldithiocarbamate (Scheme 1). In addition,
the azido Pt complex cis-[Pt(N3)2(PASO2)2] (4) was prepared
by displacement of cod from cis-[Pt(N2)3(cod)] by PASO2, as
shown in Scheme 1. We also tried to prepare gold(I) alkynyl
complexes by the reaction of 2 with alkynes in the presence of
base. However, due to the poor solubility of 2, only starting
materials were recovered even after prolonged reaction times.
Complexes 2-4 are also insoluble in common solvents
including water, acetone, acetonitrile, alcohols, and haloge-
nated solvents and dissolve only poorly in dmso and dmf.
Thus, exchange of the chloride ligands with other ligands
Since both 31P chemical shifts as well as the magnitude of
the Pt-P coupling constants in metal phosphine complexes
are affected by the nature of the phosphine, it is appropriate
to compare the data of some PASO2 and PTA complexes
(Table 2).
It can be seen that the 31P NMR chemical shifts of the Au
and Pt PASO2 complexes experience a higher coordination
shift (ΔP) than those of the analogous PTA complexes. In
addition, the Pt-P coupling constant is considerably larger in
the PASO2 derivatives. The downfield shift is due to removal of
electron density at phosphorus (due to coordination to the
metal). These data show that despite their structural similarity,
(27) Smoleski, P.; Mukhopadhyay, S.; Guedes da Silva, M. F. C.;
ꢀ
´
lia Januario Charmier, M.; Pombeiro, A. J. L. Dalton Trans. 2008,
Adı
6546.
(28) Fleischer, A.; Roller, A.; Arion, V. B.; Keppler, B. K.; Mohr, F.
Can. J. Chem. 2009, 87, 146.

Article
Organometallics, Vol. 29, No. 17, 2010 3925
Scheme 2
Figure 3. Molecular structure of compound 5. Ellipsoids show
50% probability levels. Hydrogen atoms have been omitted for
clarity.
Figure 5. Molecular structure of one of the independent mole-
cules of compound 7a. Ellipsoids show 50% probability levels.
Hydrogenatomsaswellasthe Cl- anion and the H2O of crystalliza-
tion have been omitted for clarity.
Table 3. Comparison of Selected Bond Distances in PASO2 and
PTA Ru and Rh Complexes
complex
M-P
M-Cl
M-Ca
[Ru(η6-p-cym)Cl2(PASO2)] (5)
2.2910(10) 2.4175(10) 1.699
2.4144(10)
[Ru(η6-p-cym)Cl2(PTA)]29
[Rh(η5-C5Me5)Cl2(PASO2)] (6)
[Rh(η5-C5Me5)Cl2(PTA)]30
2.296(2)b
2.298(3)
2.2657(6)
2.42c
2.43
1.692
1.816
1.804
1.857
1.859
Figure 4. Molecular structure of compound 6. Ellipsoids show
50% probability levels. Hydrogen atoms have been omitted for
clarity.
2.4115(5)
2.4117(6)
2.410(1)
2.417(1)
2.4010(6)
2.286(1)
PASO2 has a different influence on the 31P NMR chemical shift
and the Pt-P coupling constants than PTA.
[Rh(η5-C5Me5)Cl(PASO2)2]Cl (7a) 2.2957(7)
2.2942(6)
[Rh(η5-C5Me5)Cl(PTA)2]Cl30
2.291(2)
2.288(2)
2.405(2)
Organometallic Ruthenium(II) and Rhodium(III) Complexes.
Two equivalents of PASO2 react with the Ru(II) and Rh(III)
dimers [Ru(η6-p-cym)Cl2]2 and [Rh(η5-C5Me5)Cl2]2 to give the
monomeric Ru and Rh complexes [Ru(η6-p-cym)Cl2(PASO2)] (5)
a Distance between the metal and the calculated centroid of the aro-
matic ring. b Two independent molecules per asymmetric unit. c Average
distances from two independent molecules.
and [Rh(η5-C5Me5)Cl2(PASO2)] (6), respectively (Scheme 2).
Similarly, the reaction of [Rh(η5-C5Me5)Cl2]2 with four equiva-
lents of PASO2 affords the cationic Rh(III) complex [Rh(η5-
C5Me5)Cl(PASO2)2]þ, which was isolated as the BPh4 salt (7).
(29) Allardyce, C. S.; Dyson, P. J.; Ellis, D. J.; Heath, S. L. Chem.
Commun. 2001, 1396.
~
(30) Dorcier, A.; Ang, W. H.; Bolano, S.; Gonsalvi, L.; Juillerat-
Jeannerat, L.; Laurenczy, G.; Peruzzini, M.; Phillips, A. D.; Zanobini,
F.; Dyson, P. J. Organometallics 2006, 25, 4090.

3926 Organometallics, Vol. 29, No. 17, 2010
Sternberg et al.
Scheme 3
X-ray quality crystals of the chloride salt (7a) were obtained
when a CH2Cl2 solution of [Rh(η5-C5Me5)Cl2]2 containing an
excess of PASO2 was shaken with water in an attempt to extract
the salt into the aqueous phase.
Complexes 5-7 are considerably more soluble than the
aforementioned Au and Pt complexes. Although neither of
them is soluble in water, they are soluble in acetone, aceto-
nitrile, CH2Cl2, and dmso. This reasonable solubility in a
wide range of solvents allowed us to obtain X-ray quality
crystals of complexes 5, 6, and 7a, the molecular structures of
which are shown in Figures 3-5; selected bond distances
together with those of the analogous PTA complexes are
shown in Table 3.
The overall geometry of the half-sandwich “piano-stool”
PASO2 complexes 5-7a is basically identical to that of the
corresponding PTA29,30 complexes and also typical for arene
Ru(II) or Cp* Rh(III) phosphine complexes. While the M-P,
M-Cl, and M-Cring bond lengths of the Ru complex 5 and the
cationic Rh complex 7a are very similar for both PASO2 and
PTA, the neutral Cp* Rh PASO2 complex 6has a slightly shorter
Rh-P bond distance but a longer Rh-Cring bond distance when
compared to those of its PTA analogue. These data show that
the different stereoelectronic properties of the phosphines are not
reflected in the structures (bond distances) of the complexes.
How reactivity of the compounds, e.g., in catalysis, is influenced
by the different phosphines is currently being investigated.
The NMR spectroscopic data of complexes 5-7 are
similar to those of the Au and Pt complexes discussed above:
singlet or doublet (P-Rh coupling) resonances for the Ru
and Rh complexes, respectively, are observed in the 31P
NMR spectra. Unfortunately, there are no chemical shift
data available in the same solvent for the PTA congeners,
making a meaningful comparison difficult.
Figure 6. Molecular structure of compound 8. Ellipsoids show 50%
probability levels. Hydrogen atoms have been omitted for clarity.
Figure 7. Molecular structure of compound 9. Ellipsoids show
50% probability levels. Hydrogen atoms as well as the disordered
CH2Cl2 molecule of solvation have been omitted for clarity.
Cyclometalated Palladium(II) Complexes. PASO2 reacts
with the cyclometalated chloro-bridged Pd(II) dimers
[PdCl{κC,N-C6H4C(Ph)NCH2CO2Et}]2 and [PdCl{κC,N-
1,8-C10H6NMe2}]2 to give the bridge cleavage products
[PdCl{κC,N-C6H4C(Ph)NCH2CO2Et}(PASO2)] (8) and
[PdCl(κC,N-1,8-C10H6NMe2)(PASO2)] (9), respectively, as
yellow solids in high yield (Scheme 3). Compounds 8 and 9
are insoluble in water, ether, and hexane but soluble in ace-
tone and halogenated solvents. Single crystals were obtained
of both compounds, which allowed us to determine the solid-
state structure by X-ray diffraction. The molecular struc-
tures are shown in Figures 6 and 7.
palladacycles with monodentate phosphines and is also
consistent with the transphopbia principle that explains the
avoidance of mutually trans phosphorus and aryl carbon
atoms at a palladium(II) center.31 The bond distances and
angles of complexes 8 and 9 are typical for orthometalated
Pd phosphine complexes and are similar to those observed in
the PTA complex [PdCl{κC,N-C6H4CH2NMe2}(PTA)], one
of the very few known palladacycles containing PTA.32,33
(31) Palladacycles; Dupont, J.; Pfeffer, M., Eds.; Wiley-VCH: Weinheim,
2008.
(32) Ruiz, J.; Cutillas, N.; Lopez, F.; Lopez, G.; Bautista, D.
In both compounds, the phosphine ligand is located trans
to the nitrogen atom in the square-planar coordination environ-
ment about the palladium atom. This behavior is typically
observed in bridge-cleavage reactions of chloro-bridged
Organometallics 2006, 25, 5768.
(33) Spencer, J.; Casini, A.; Zava, O.; Rathnam, R. P.; Velhanda,
S. K.; Pfeffer, M.; Callear, S. K.; Hursthouse, M. B.; Dyson, P. J. Dalton
Trans. 2009, 10731.

Article
In conclusion, we have shown by both computational and
Organometallics, Vol. 29, No. 17, 2010 3927
The mixture was left to stir for ca. 18 h. The precipitated colorless
solid was isolated by filtration, washed with H2O, MeOH, and Et2O,
and subsequently left to dry in air. Yield: 0.028 g (52%). 31P{1H}
NMR (162 MHz, dmso-d6):δ-53.6. 1H NMR (400 MHz, dmso-d6):
δ 2.23 (s, 6 H, Me), 4.36 (s, 2 H, PCH2NS), 4.69-5.20 (m, 8 H,
PCH2N, NCH2N), 6.73 (s, 1 H, Arom). Anal. Calcd for
C11H17N5O2PS2Au: C, 24.32; H, 3.15; N, 12.89. Found: C, 24.11;
H, 3.00; N, 13.16.
spectroscopic methods that PASO2 is a phosphine with
unique stereoelectronic properties. In terms of its chemical
reactivity, the compound undergoes typical reactions of a
phosphine with various transition metal precursors, which
we demonstrated by examining its complexes containing
Mo, Au, Pt, Pd, Ru, and Rh. Just how the stereoelectronic
properties of PASO2 influence the catalytic and biological
properties of its complexes is currently being further investi-
gated in our group.
[Au(S2CNEt2)(PASO2)] (2b). To a suspension of [AuCl-
(PASO2)] (0.100 g, 0.227 mmol) in MeOH (10 mL) was added
the sodium diethyldithiocarbamate (0.056 g, 0.327 mmol). The
mixture was left to stir for ca. 18 h. The precipitated dark yellow
solid was isolated by filtration, washed with H2O, MeOH, and
Et2O, and subsequently left to dry in air. Yield: 0.126 g (quanti-
tative). 31P{1H} NMR (162 MHz, dmso-d6): δ -60.9. 1H NMR
(400 MHz, dmso-d6): δ 1.20 (t, J=7.2 Hz, 6 H, Me), 3.78 (q, J=
7.2 Hz, 4 H, NCH2), 4.28 (s, 2 H, PCH2NS), 4.68-5.28 (m, 8 H,
PCH2N, NCH2N). Anal. Calcd for C10H20N4O2PS3Au: C,
21.74; H, 3.65; N, 10.14. Found: C, 21.66; H, 3.77; N, 10.40.
[Au(S2CNBz2)(PASO2)] (2c). This was prepared as above
from [AuCl(PASO2)] (0.100 g, 0.227 mmol) and sodium dibenzyl-
dithiocarbamate (0.074 g, 0.251 mmol). Yield: 0.119 g (77%), pale
Experimental Section
General Procedures. 1H, 13C, and 31P{1H} NMR spectra were
recorded on a 400 MHz Bruker Avance spectrometer. Chemical
shifts are quoted relative to external SiMe4 (1H, 13C) and H3PO4
(31P). Elemental analyses were performed by staff of the micro-
analytical laboratory of the University of Wuppertal. High-
resolution electrospray mass spectra were recorded on a Bruker
Daltonics MicroTOF instrument in positive ion mode from
MeCN solutions. IR spectra were recorded on a Bruker Tensor
27 FT-IR spectrometer fitted with an ATR unit. All reactions
were carried out under aerobic conditions unless stated other-
wise. The phosphine PASO2 as well as the metal precursors
[AuCl(tht)] (tht = tetrahydrothiophene), cis-[PtCl2(cod)], cis-
[Pt(N3)2(cod)] (cod = 1,5-cyclooctadiene), [Ru(η6-p-cym)Cl2]2
(p-cym=p-cymene), [Rh(η5-C5Me5)Cl2]2, [PdCl{κC,N-C6H4C-
(Ph)NCH2CO2Et}]2, [PdCl{κC,N-1,8-C10H6NMe2}]2, and cis-
[Mo(CO)4(pip)2] (pip=piperidine) were prepared as described
in the literature.3,21,34-40 All other chemicals and solvents
(HPLC or extra dry grade) were sourced commercially and used
as received.
1
yellow solid. 31P{1H} NMR (162 MHz, dmso-d6): δ -58.7. H
NMR (400 MHz, dmso-d6):δ4.33 (s, 2 H, PCH2NS), 4.73-5.25 (m,
10 H, PCH2N, NCH2N, NCH2), 7.28-7.42 (m, 10 H, Ph). Anal.
Calcd for C20H24N4O2PS3Au: C, 35.50; H, 3.58; N, 8.28. Found: C,
35.83; H, 3.40; N, 8.51.
cis-[PtCl2(PASO2)2] (3). To a solution of cis-[PtCl2(cod)]
(0.100 g, 0.267 mmol) in CH2Cl2 (10 mL) was added a solution
of PASO2 (0.111 g, 0.536 mmol) in CH2Cl2 (20 mL). After ca.
15 min the colorless precipitate was isolated by filtration, washed
with Et2O, and dried in air. Yield: 0.159 g (87%). 31P{1H} NMR
1
(162 MHz, dmso-d6): δ -64.0 JPt-P = 3387 Hz. H NMR (400
cis-[Mo(CO)4(PASO2)2] (1). A mixture of cis-[Mo(CO)4-
(pip)2] (0.150 g, 0.393 mmol) and PASO2 (0.166 g, 0.801 mmol)
in CH2Cl2 (15 mL) was heated under nitrogen to reflux for ca.
10 min. The resulting orange solution was passed through Celite
and the filtrate concentrated under vacuum. Addition of MeOH
precipitated the product as a pale yellow solid in 85% yield
(0.208 g). 31P{1H} NMR (162 MHz, dmso-d6): δ -61.4.
1H NMR (400 MHz, dmso-d6): δ 4.11 (s, 4 H, PCH2NS), 4.62
(AB quart., J=16.2 Hz, 8 H, PCH2N), 5.01 (AB quart., J=
13.4 Hz, 8 H, NCH2N). IR (ATR): 2033, 1923, 1872, 1825 ν(CO)
cm-1. Anal. Calcd for C14H24N6O8P2SMo: C, 26.84; H, 3.86; N,
13.42. Found: C, 26.93; H, 3.77; N, 13.32.
[AuCl(PASO2)] (2). To a solution of [AuCl(tht)] (0.100 g,
0.312 mmol) in CH2Cl2 (10 mL) was added a solution of PASO2
(0.065 g, 0.314 mmol) in CH2Cl2 (15 mL). After ca. 30 min the
colorless precipitate was isolated by filtration, washed with
Et2O, and dried in air. Yield: 0.124 g (91%). 31P{1H} NMR
(162 MHz, dmso-d6): δ -56.6. 1H NMR (400 MHz, dmso-d6): δ
4.35 (s, 2 H, PCH2NS), 4.90 (AB quart., J = 15.6 Hz, 4 H,
PCH2N), 4.96 (AB quart., J=13.2 Hz, 4 H, NCH2N). Anal.
Calcd for C5H10N3O2PSClAu: C, 13.66; H, 2.29; N, 9.56. Found: C,
13.55; H, 2.08; N, 9.23.
MHz, dmso-d6): δ 4.47 (s, 4 H, PCH2NS), 4.92 (AB quart., J=
15.6 Hz, 8 H, PCH2N), 4.99 (AB quart., J=13.2 Hz, 8 H, NCH2N).
Anal. Calcd for C10H20N6O4P2S2Cl2Pt: C, 17.65; H, 2.96; N, 12.35.
Found: C, 17.58; H, 3.00; N, 12.21.
[Pt(N3)2(PASO2)2] (4). To a solution of cis-[Pt(N3)2(cod)]
(0.050 g, 0.129 mmol) in CH2Cl2 (5 mL) was added a solution
of PASO2 (0.055 g, 0.265 mmol) in CH2Cl2 (10 mL). After ca. 1 h
the colorless precipitate was isolated by filtration, washed with
MeOH, and dried in air. Yield: 0.077 g (85%). 31P{1H} NMR
(162 MHz, dmso-d6): δ -68.9 JPt-P=3257 Hz. 1H NMR (400
MHz, dmso-d6): δ 4.36 (s, 4 H, PCH2NS), 4.73-5.21 (m, 16 H,
PCH2N, NCH2N). IR (KBr disk): 2064 ν(N3) cm-1. Anal. Calcd
for C10H20N12O4P2S2Pt: C, 17.32; H, 2.91; N, 24.24. Found: C,
17.44; H, 2.83; N, 24.07.
[Ru(η6-p-cym)Cl2(PASO2)] (5). To a solution of [Ru(η6-p-
cym)Cl2]2 (0.153 g, mmol) in MeOH (10 mL) was added a
solution of PASO2 (0.079 g, 0. mmol) in MeOH2 (20 mL). After
refluxing the mixture for ca. 4 h the orange solid was isolated by
filtration, washed with MeOH, and dried in air. Yield: 0.165 g
(98%). 31P{1H} NMR (162 MHz, dmso-d6): δ -45.5. 1H NMR
(400 MHz, dmso-d6): δ 1.11 (d, J=6.9 Hz, 6 H, Me), 1.91 (s, 3 H,
Me), 2.56 (sept, J=6.9 Hz, 1 H, Me2CH), 4.29 (s, 2 H, PCH2NS),
4.66 (AB quart., J=16.7 Hz, 4 H, PCH2N), 5.00 (AB quart., J=
13.8 Hz, 4 H, NCH2N), 5.81 (dd, J=6.4/0.9 Hz, 2 H, p-cym),
5.86 (dd, J = 6.3/1.0 Hz, 2 H, p-cym). Anal. Calcd for
C15H24N3O2PSCl2Ru: C, 35.09; H, 4.71; N, 8.18. Found: C,
34.95; H, 5.01; N, 7.92. X-ray quality crystals were obtained by
slow diffusion of EtOH into a dmso solution of the compound.
[Rh(η5-C5Me5)Cl2(PASO2)] (6). To a solution of [Rh(η5-
C5Me5)Cl2]2 (0.030 g, 0.049 mmol) in MeOH (20 mL) was added
PASO2 (0.021 g, 0.101 mol). The solution was heated to reflux
for ca. 1 h. Upon cooling, a red-orange precipitate formed,
which was isolated by filtration, washed with MeOH, and
subsequently dried in air. Yield: 0.055 g (82%). 31P{1H} NMR
[Au(SMe2pyrim)(PASO2)] (2a). To a suspension of [AuCl-
(PASO2)] (0.044 g, 0.100 mmol) in MeOH (10 mL) was added the
sodium salt of 3,5-dimethylpyrimidinethiol (0.017 g, 0.105 mmol).
ꢀ
(34) Uson, R.; Laguna, A.; Laguna, M. Inorg. Synth. 1989, 26, 85.
(35) Clark, H. C.; Manzer, L. E. J. Organomet. Chem. 1973, 59, 411.
(36) Kim, Y. J.; Choi, J. C.; Park, K. H. Bull. Korean Chem. Soc. 1994,
15, 690.
(37) Bennett, M. A.; Smith, A. K. J. Chem. Soc., Dalton Trans. 1974,
233.
ꢀ
(38) El Amouri, H.; Gruselle, M.; Jaouen, G. Synth. React. Inorg.
Met. Org. Chem. 1994, 24, 395.
(39) Boehm, A.; Schreiner, B.; Steiner, N.; Urban, R.; Suenkel, K.;
Polborn, K.; Beck, W. Z. Naturforsch. B 1998, 53, 191.
(40) Komatsu, T.; Nonoyama, M. J. Inorg. Nucl. Chem. 1977, 39,
1161.
1
(162 MHz, dmso-d6): δ -45.8 (d, JRh-P =148 Hz). H NMR
(400 MHz, dmso-d6): δ 1.64 (d, J=3.9 Hz, 15 H, Me), 4.20 (s,
2 H, PCH2NS), 4.70 (AB quart., J=16.4 Hz, 4 H, PCH2N), 4.99

3928 Organometallics, Vol. 29, No. 17, 2010
Table 4. Crystallographic and Refinement Details of Compounds 5-9
Sternberg et al.
5
6
7a
8
9
empirical formula
color
C
15H24O2N3PRuSCl2
C15H25O2N3PRhSCl2
orange
516.22
monoclinic
P21/c
10.3140(3)
7.2646(2)
25.8648(9)
91.221(3)
1937.53(10)
4
1.770
1.363
1048
C20H38O5N6P2RhS2Cl2
orange
741.43
monoclinic
P21/n
9.6662(3)
12.8410(3)
22.4541(6)
92.357(3)
2784.70(12)
4
1.768
1.115
1520
C22H26O4N4PPdSCl
colorless
615.35
monoclinic
P21/c
14.2326(6)
16.3432(8)
10.3295(4)
100.316(4)
2363.85(18)
4
1.729
1.093
1248
C17.25H23N4O2PPdCl2S
pale yellow
558.73
monoclinic
P21/n
10.1513(3)
18.4785(4)
12.2060(4)
111.010(3)
2137.41(10)
4
1.736
1.313
1126
orange
513.38
monoclinic
C2/c
28.692(2)
6.6083(3)
23.5466(18)
119.812(10)
3873.8(4)
8
1.761
1.291
2080
Mr, g mol-1
cryst syst
space group
a, A
b, A
c, A
β, deg
V, A3
Z
Dcalc, g cm-3
μ, mm-1
F000
θ range
3.15 to 29.48°
9192
4539
232
0.825
0.0373
0.0639
0.863/-0.688
2.91 to 29.40°
10 661
4531
231
0.989
0.0249
0.0576
0.422/-0.535
3.15 to 29.53°
13 710
6494
348
0.905
0.0282
0.0611
0.527/-0.473
2.89 to 29.49°
150 402
5656
308
0.852
0.0377
0.0691
0.764/-0.758
3.08 to 29.45°
9779
5002
273
1.086
0.0396
0.0522
2.164/-1.742
reflns collected
indep reflns
parameters
goodness-of-fit
R1 [I > 2σ(I)]
wR2 (all data)
largest diff peak/
hole, e A-3
(AB quart., J = 13.5 Hz, 4 H, NCH2N). Anal. Calcd for
C15H25N3O2PSCl2Rh: C, 34.90; H, 4.88; N, 8.14. Found: C,
35.03; H, 4.97; N, 8.36.
(0.100 g, 0.160 mmol) and PASO2 (0.067 g, 0.323 mmol) to give
0.110 g (66%) of a pale yellow solid. 31P{1H} NMR (162 MHz,
CDCl3): δ -56.2. H NMR (400 MHz, CDCl3): δ 3.36 (2 s,
3 H each, NMe), 4.59 (s, 2 H, PCH2NS), 5.01 (AB quart., J=
16.0 Hz, 4 H, PCH2N), 5.02 (AB quart., J = 13.7 Hz, 4 H,
NCH2N), 7.34 (t, J=7.0 Hz, 1 H, Arom), 7.38 (t, J=7.6 Hz, 1 H,
Arom), 7.45-7.51 (m, 2 H, Arom), 7.65 (d, J=8.0 Hz, 1 H,
Arom), 7.72 (dd, J=7.2/1.6 Hz, 1 H, Arom). Anal. Calcd for
1
[Rh(η5-C5Me5)Cl(PASO2)2]BPh4 (7). To
a solution of
[Rh(η5-C5Me5)Cl2]2 (0.030 g, 0.049 mmol) in MeOH (20 mL)
was added PASO2 (0.042 g, 0.203 mol). The solution was heated
to reflux for ca. 1 h, and then Na[BPh4] (0.037 g, excess) was
added. After cooling to rt, the solvent was removed under
vacuum and the yellow residue was extracted with CH2Cl2.
The solution was passed through Celite, and addition of Et2O
precipitated a yellow solid. This was isolated by filtration,
washed with H2O and Et2O, and subsequently dried in air.
Yield: 0.078 g (80%). 31P{1H} NMR (162 MHz, acetone-d6): δ
-50.9 (d, JRh-P=136 Hz). 1H NMR (400 MHz, acetone-d6): δ
2.81 (s, 15 H, Me), 4.56 (s, 5 H, PCH2NS), 4.83-5.09 (m, 16 H,
PCH2N, NCH2N), 6.77 (t, J=7.2 Hz, 4 H, p-BPh4), 6.92 (t, J=
7.4 Hz, 8 H, m-BPh4), 7.34 (m, 8 H, o-BPh4). Anal. Calcd for
C44H55N6O4P2S2ClBRh: C, 52.47; H, 5.50; N, 8.34. Found: C,
52.63; H, 5.53; N, 8.53. Positive ion HR-ES-MS (m/z): 687.0375
[M]þ, 480.0140 [M - PASO2]þ. X-ray quality crystals of the
chloride salt (7a) were obtained by combining small quantities of
[Rh(η5-C5Me5)Cl2]2 and PASO2 in a vial with CH2Cl2 and
shaking with H2O (in an attempt to extract any water-soluble
complex). Orange needles were formed after standing for 48 h.
[PdCl{KC,N-C6H4C(Ph)NCH2CO2Et}(PASO2)] (8). To a
solution of [PdCl{κC,N-C6H4C(Ph)NCH2CO2Et}]2 (0.050 g,
0.061 mmol) in CH2Cl2 (10 mL) was added PASO2 (0.025 g,
0.120 mmol), and the mixture was stirred at rt for ca. 1 h. The
solution was passed through Celite and concentrated under
vacuum. Careful addition of hexane afforded fine, pale yellow
needles after standing for several hours. These were isolated by
filtration and dried in air. Yield: 0.056 g (75%). 31P{1H} NMR
(162 MHz, dmso-d6): δ -57.1. 1H NMR (400 MHz, dmso-d6): δ
1.12 (t, J=7.1 Hz, 3 H, Me), 4.05 (q, J=7.1 Hz, 2 H, OCH2), 4.48
(s, 2 H, NCH2), 4.52 (s, 2 H, PCH2NS), 5.00 (AB quart., J=16.2
Hz, 4 H, PCH2N), 5.07 (AB quart., J=13.8 Hz, 4 H, NCH2N),
6.62 (dd, J=7.6/1.5 Hz, 1 H, H6), 7.08 (dt, J=7.7/0.7 Hz, 1 H,
H5), 7.25 (dt, J=7.5/1.5 Hz, 1 H, H4), 7.27-7.30 (m, 2 H, o-Ph),
7.35 (d, J=7.6 Hz, 1 H, H3), 7.57-7.61 (m, 3 H, m-Ph, p-Ph).
Anal. Calcd for C22H26N4O4PSClPd: C, 42.94; H, 4.26; N, 9.10.
Found: C, 43.17; H, 4.11; N, 9.38. X-ray quality crystals were
selected from the bulk sample.
C22H26N4O4PSClPd 1/2CH2Cl2: C, 37.42; H, 4.13; N, 9.97.
Found: C, 37.60; H, 4.33; N, 10.15. X-ray quality crystals were
selected from the bulk sample.
3
X-ray Diffraction Studies. Diffraction data were collected at
150 K using an Oxford Diffraction Gemini E Ultra diffract-
ometer, equipped with an EOS CCD area detector and a four-
circle kappa goniometer. For the data collection the Mo source
emitting graphite-monochromated Mo KR radiation (λ =
0.71073 A) was used. Data integration, scaling, and empirical
absorption correction were carried out using the CrysAlis Pro
program package.41 The structure was solved using direct
methods and refined by full-matrix-least-squares against F2.
The non-hydrogen atoms were refined anisotropically, and
hydrogen atoms were placed at idealized positions and refined
using the riding model. All calculations were carried out using
the program Olex2.42 Important crystallographic data and
i
refinement details are summarized in Table 4. The Pr group
of the p-cymene ring in complex 5 was disordered over two
positions caused by rotation about the CH-Ar axis. The
disordered group was refined isotropically. Complex 7a crystal-
lized with one molecule of water in the unit cell, the hydrogen
atoms of which were not located. The unit cell of complex 9
contained half a molecule of CH2Cl2, the carbon atom of which
was located on an inversion center disordered over two posi-
tions. The occupancy factors of the chlorine atoms were refined;
the carbon atom was split over the two positions with 25%
occupancy each, and the C-Cl distances were fixed at 1.74 A.
No hydrogen atoms were added to the disordered CH2Cl2
molecule. The highest remaining electron density peaks are
located close to the Cl atoms of the disordered solvent.
Computational Studies. Full geometry optimization of PTA
and PASO2 ligands was done using the B3LYP/6-31G(d,p) level
(41) CrysAlis Pro 171.33.42; Oxford Diffraction Ltd., 2009.
(42) Dolomanov, O. V.; Bourhis, L. J.; Gildea, R. J.; Howard,
J. A. K.; Puschmann, H. J. Appl. Crystallogr. 2009, 42, 339.
[PdCl(KC,N-1,8-C10H6NMe2)(PASO2)] (9). This was pre-
pared as described above from [PdCl{κC,N-1,8-C10H6NMe2}]2

Article
Organometallics, Vol. 29, No. 17, 2010 3929
of density functional theory (DFT). Further, the hybrid QM-MM
level optimization of the ligands was done using the ONIOM-
(B3LYP/6-31G(d,p):UFF) method. At both DFT and QM-MM
levels, the molecular electrostatic potential (MESP) of the ligands
was calculated. The most negative-valued point of the MESP
(designated as Vmin) at the lone pair region of the phosphorus
atom was determined at both levels of calculation. All the calcula-
tions were done using the Gaussian03 suite of programs.26
Acknowledgment. We thank the DFG for a grant to
purchase the diffractometer as well as the University of
Wuppertal for funding.
Supporting Information Available: Full crystallographic details
of compounds 5-9 in CIF format as well as further details on the
computational studies are available free of charge via the Internet
at http://pubs.acs.org.