Gold(I) phosphine complexes containing selenocarbamate esters: Crystal and molecular structure of N-phenyl-O-methylselenocarbamate

Article abstract of DOI:10.1080/10426500801901087

A series of both mono- and dinuclear gold(I) phosphine complexes containing deprotonated N-phenyl-O-methylselenocarbamate of the type [AuSeC(OMe) = NPh(P)] and [Au₂SeC(OMe) = NPh₂(PP)] (P = PPh₃, P(o-tolyl)₃, PTA; PP = dppm, dppe, dppp, dppf) were prepared and characterized by spectroscopic techniques. The X-ray crystal structure of SeC(OMe)=N(H)Ph is also reported and shows the molecule to exist in the E-conformation. Centrosymmetrically related dimers associate in the crystal structure by N-H...Se interactions.

Full text of DOI:10.1080/10426500801901087

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Phosphorus, Sulfur, and Silicon
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Gold(I) Phosphine Complexes
Containing Selenocarbamate
Esters: Crystal and Molecular
Structure of N-phenyl-O-
methylselenocarbamate
Daniel Gallenkamp a , Edward R. T. Tiekink b &
Fabian Mohr a
a Fachbereich C—Anorganische Chemie, Bergische
Universität , Wuppertal, Germany
b Department of Chemistry , The University of Texas
at San Antonio , San Antonio, Texas, USA
Published online: 29 Oct 2008.
To cite this article: Daniel Gallenkamp , Edward R. T. Tiekink & Fabian Mohr
(2008) Gold(I) Phosphine Complexes Containing Selenocarbamate Esters:
Crystal and Molecular Structure of N-phenyl-O-methylselenocarbamate,
Phosphorus, Sulfur, and Silicon and the Related Elements, 183:4, 1050-1056, DOI:
10.1080/10426500801901087
To link to this article: http://dx.doi.org/10.1080/10426500801901087
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Phosphorus, Sulfur, and Silicon, 183:1050–1056, 2008
Copyright © Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500801901087
Gold(I) Phosphine Complexes Containing
Selenocarbamate Esters: Crystal and Molecular Structure
of N-phenyl-O-methylselenocarbamate
Daniel Gallenkamp,1 Edward R. T. Tiekink,2
and Fabian Mohr1
1Fachbereich C—Anorganische Chemie, Bergische Universita¨t
Wuppertal, Germany
2Department of Chemistry, The University of Texas at San Antonio,
San Antonio, Texas, USA
A series of both mono- and dinuclear gold(I) phosphine complexes containing de-
protonated N-phenyl-O-methylselenocarbamate of the type [AuSeC(OMe)=NPh(P)]
and [Au SeC(OMe)=NPh (PP)] (P = PPh , P(o-tolyl) , PTA; PP = dppm, dppe,
2
2
3
3
dppp, dppf) were prepared and characterized by spectroscopic techniques. The X-
ray crystal structure of SeC(OMe) N(H)Ph is also reported and shows the molecule
to exist in the E-conformation. Centrosymmetrically related dimers associate in the
. . .
crystal structure by N
H
Se interactions.
. . .
Se hydrogen-bonding; gold; phosphine complexes;
Keywords Crystal structure; N
H
selenium; selenocarbamate ester
INTRODUCTION
The chemistry of gold(I) phosphine complexes with sulfur ligands is to-
day a well established field. A large number of such compounds have
been prepared and some interesting applications have emerged due
to their luminescent properties and biological activity.1 Particularly
in medicinal applications, gold thiolate complexes have shown much
promise; the gold(I) complex auranofin (Figure 1) is one of the leading
anti-arthritis drugs on the market.2
In contrast, the chemistry of gold(I) complexes containing selenium
is relatively unexplored. The known complexes are generally restricted
to those derived from selenium ligands, which are either commercially
We thank the Fonds der Chemischen Industrie as well as the University of Wuppertal
for generous financial support of this work.
Address correspondence to Fabian Mohr, Fachbereich C. Anorganische Chemie,
Bergische Universita¨t Wuppertal, 42119 Wuppertal, Germany. E-mail: fmohr@uni-
wuppertal.de
1050

Gold(I) Phosphine Complexes Containing Selenocarbamate Esters
1051
FIGURE 1 Examples for gold(I) thiolate based drugs.
available or easily accessible. The preparation, structures and photo-
physical properties of a series of gold(I) phosphine complexes contain-
ing thiocarbamate esters has been reported.3−6 In order to establish if
there are differences in the behaviour of the analogous selenium ana-
logues, we synthesized and characterized a series of gold(I) complexes
containing N-phenyl-O-methylselenocarbamate. Some initial results of
this investigation are communicated herein.
RESULTS AND DISCUSSION
The synthesis of N-phenyl-O-methylselenocarbamate and the cobalt(II)
complexes [CoX2SeC(OMe) NPh2] (X Cl, Br, I) was reported as early
as 1971, but since then this ligand has never been used again.7 We
obtained N-phenyl-O-methylselenocarbamate by the reaction of N-
phenylisoselenocyanate8 with MeOH in the presence of KOH in 80 %
yield as a colorless, extremely malodorous solid (Scheme 1).
SCHEME 1
N-phenyl-O-methylselenocarbamate was characterized by various
spectroscopic techniques including 1H, 13C and 77Se NMR spectroscopy,
IR spectroscopy and mass spectrometry. The analogous sulfur com-
pound exists in solution as a mixture of E and Z isomers, as was shown
by low temperature4 1H-NMR spectroscopy; in the solid-state however,
the compound exists as the E isomer. We found that the 1H-NMR spec-
trum of N-phenyl-O-methylselenocarbamate does not change on cooling
from room temperature to −60◦C, suggesting that either no conforma-
tion change occurs at all or that the conformation change is fast on the
NMR timescale even at −60◦C. The IR spectrum shows strong bands
due to the N H and C N stretches at 3149 and 1537 cm−1, respec-
tively. The band due to the C Se stretch could not be located in the

1052
D. Gallenkamp et al.
FIGURE 2 Dimer formation mediated by N–H· · ·Se interactions in the
structure of N-phenyl-O-methylselenocarbamate showing the atom-labelling
scheme and displacement ellipsoids at the 70% probability level. Selected geo-
◦
˚
metric parameters [A, ]: C1–Se1 1.8322(19), C1–O1 1.322(2), C1–N1 1.328(2),
Se1–C1–O1 124.60(14), Se1–C1–N1 122.07(14), O1–C1–N1 113.29(16), and
C1–N1–C2 126.06(16). The dashed lines show the N–H· · ·Se hydrogen-bonding
i
i
˚
˚
interactions: N1–H· · ·Se1 = 2.60 A, N1–H· · ·Se1 3.4451(19) A, with an angle
of 162o at H for symmetry operation i: -x, 1-y, 1-z.
fingerprint region of the spectrum. The compound was fully character-
ized by single-crystal X-ray diffraction methods.
The molecular structure is shown in Figure 2 and selected geometric
parameters are collected in the figure caption. The central COC( Se)N
chromophore is essentially planar as seen in the Se1/C1/N1/C2 and
C8/O1/C1/N1 torsion angles of 178.90(14) and 175.50(16)◦, respectively.
However, the N1-phenyl ring is not co-planar with these atoms: the
C1/N1/C2/C3 torsion angle is 124.0(2)◦. The C1 Se1 bond falls within
9
˚
the range expected for a C Se double bond, i.e., 1.82–1.87 A. The con-
formation of the molecule about the C1-N1 bond, which at 1.328(2)
˚
A has some multiple bond character indicating restricted rotation, is
E. The angles subtended at the C1 atom by the Se1 atom are larger
than the O1–C1–N1 bond, in accord with expectation. Overall, the
molecular structure is as reported for the sulfur analogue, indeed the
structures are isomorphous.4a Molecules associate in the solid-state
. . .
via N H Se hydrogen-bonding interactions. The dimeric units thus
formed are connected into supramolecular chains aligned along the

Gold(I) Phosphine Complexes Containing Selenocarbamate Esters
1053
FIGURE 3 Unit cell contents for N-phenyl-O-methylselenocarbamate viewed
down the a-direction. Dashed lines represent C–H· · ·Se hydrogen-bonding in-
teractions.
10
. . .
a-direction via C H Se interactions. These chains are connected to
adjacent chains via weak π · · · π interactions to form layers that stack
along the b-direction. Connections between layers are of the type C–
H· · ·π; a view of the unit cell contents down the a-direction, is shown in
Figure 3.
A
series of both mono- and dinuclear gold(I) phosphine
complexes were prepared by deprotonation of N-phenyl-O-
methylselenocarbamate in the presence of the appropriate chlorophos-
phinegold(I) complexes as shown in Scheme 2. The new gold complexes
could be isolated as colorless or pale-yellow solids in good yields
and were characterized by 1H and 31P-NMR spectroscopy and IR
spectroscopy.11 The combination of the poor solubility of the compounds

1054
D. Gallenkamp et al.
SCHEME 2
and the extremely low sensitivity of the 77Se nucleus did not allow
us to obtain any 77Se-NMR spectra. The chemical shifts of the singlet
resonances in the 31P-NMR spectra are typical for phosphinegold(I)
complexes. Deprotonation of the ligand is confirmed in both the 1H
and IR spectra through the absence of signals due to the NH group.
In addition, the C N stretching frequencies in the IR spectra are
shifted to higher wave numbers (ca. 1620 cm−1) compared to those of
the protonated ligand. These complexes thus represent the very first
examples of metal complexes containing deprotonated N-phenyl-O-
methylselenocarbamate. The solid-state structures of the binuclear
complexes containing 1,2-bis(diphenylphosphino)ethane (dppe) and
1,1ꢀ-bis(diphenylphosphino)ferrocene (dppf) were determined by single
crystal X-ray diffraction. While the full crystallographic details will
be published separately, the results show some very interesting and
unique features. In both cases, the gold atoms are oriented away
from each other, which means that no short intramolecular Au· · ·Au
interactions are possible.
In conclusion, we present here the preparation and characterisation
of the first gold(I) phosphine complexes containing deprotonated N-
phenyl-O-methylselenocarbamate ligands. Further studies of this class
of compounds as well as their luminescence properties are currently in
progress.
EXPERIMENTAL
N-phenyl-O-methylselenocarbamate was prepared as described for the
sulfur analog4b from N-phenylisoselenocyanate8 in 80 % yield. 1H-NMR
(CDCl3): δ = 4.26 (s, 3H, OMe), 7.17-7.41 (m, 5 H, Ph), 9.02 (br. S, 1 H,
NH); 77Se-NMR (acetone-d6): δ = 279 (s); IR (KBr disk): ν = 3149 (N-H),
1537 (N-C) cm−1; LS-MS (m/z): 215 [M]+, 430 [M2]+.

Gold(I) Phosphine Complexes Containing Selenocarbamate Esters
1055
X-Ray Crystallography
Intensity data for N-phenyl-O-methylselenocarbamate, grown from the
slow evaporation of a dichloromethane solution of the compound, were
measured at 153 K on a Rigaku AFC12/Saturn724 CCD fitted with Mo
Kα radiation. Data processing and absorption correction were accom-
plished with Crystal Clear12 and ABSCOR,13 respectively. The struc-
ture was solved by direct-methods14 and refinement (anisotropic dis-
placement parameters, hydrogen atoms in the riding model approxi-
mation and a weighting scheme of the form w = 1/[σ2(Fo2)+ (0.033P)2+
0.249P] for P = (F2+ 2F2)/3) was on F2.15
o
c
Crystal Data
C8H9NOSe, M = 214.12, triclinic space group P-1, a = 5.8383(8) A, b =
˚
o
o
˚
˚
3
8.4283(13) A, c = 9.8029(9) A, α = 63.798(12) , β = 76.045(15) , γ =
84.134(18) , V = 420.02(9) A , Z = 2, Dx = 1.693 g cm−3, μ = 4.409
o
˚
mm−1, θmax = 26.5o, 1750 independent data, 1733 data with I ≥ 2σ(I),
R = 0.024, Rw (all data) = 0.060, ρmax = 0.46 e A−3. CCDC deposition
˚
number: 651738.
Figures 2 and 3 were drawn with the ORTEP16 and DIAMOND17
programmes, respectively. Data manipulation and interpretation were
with teXsan18 and PLATON.19
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[10] Details of intermolecular interactions:
ii
. . .
. . .
˚
2.97 A,
C
H
Se: C7–H7 Se1
=
ii
◦
. . .
˚
C7 Se1 = 3.877(3) A, angle at H7 = 159 for symmetry operation ii: 1-x, 1-y,
1-z. π · · · π: ring centroid(C3-C7)· · ·ring centroid (C3-C7)iii = 3.8120(14) A for iii:
˚

1056
D. Gallenkamp et al.
-x, 1-y, 2-z. C–H· · ·π: C8–H8b· · ·ring centroid(C3-C7)iv = 2.82 A and angle at H8b
= 124◦ for iv: 1-x, 2-y, 1-z.
˚
[11] Full experimental details as well as all characterization data will be published
separately later.
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lands, TX, 2005).
[13] T. Higashi, ABSCOR (Rigaku Corporation, Tokyo, Japan, 1995).
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