Reactions of potassium bis(phosphinimino)methanide with group 11 compounds

Article abstract of DOI:10.1021/ic060932p

Transmetalation of the potassium methanide complex, K{CH(PPh ₂NSiMe₃)₂}, with [(Ph₃P) ₂Cul] afforded the corresponding copper complex [{CH(PPh ₂NSiMe₃)₂}CuPPh₃] (1), whereas the reaction of K{CH(PPh₂NSiMe₃)₂} with [Ph ₃PAuCl] resulted in the dinuclear gold complex [(Ph ₃PAu)₂{C(PPh₂NSiMe₃)₂}] (2). The solid-state structure of 1 shows the formation of a six-membered metallacycle (N1-P1-C1-P2-N2-Cu) that has a twist boat conformation. In contrast, compound 2 is an α,α-diaurated species, in which the two gold atoms are coordinated in a linear fashion onto the ligand backbone. Photoluminescence measurements show that the latter compound has a strong violet emission.

Full text of DOI:10.1021/ic060932p

Inorg. Chem. 2006, 45, 7503−7508
Reactions of Potassium Bis(phosphinimino)methanide with Group 11
Compounds
Tarun K. Panda,† Peter W. Roesky,*,† Patrick Larsen,‡ Shuang Zhang,‡ and Claudia Wickleder*,‡
Institut fu¨r Chemie und Biochemie, Freie UniVersita¨t Berlin, Fabeckstrasse 34-36, 14195 Berlin,
Germany, and Anorganische Chemie, UniVersita¨t Siegen, 57068 Siegen, Germany
Received May 29, 2006
Transmetalation of the potassium methanide complex, K
corresponding copper complex [ CH(PPh2NSiMe3)2 CuPPh3] (1), whereas the reaction of K
with [Ph3PAuCl] resulted in the dinuclear gold complex [(Ph3PAu)2 C(PPh2NSiMe3)2 ] (2). The solid-state structure
of 1 shows the formation of a six-membered metallacycle (N1 P1 C1 P2 N2 Cu) that has a twist boat conformation.
In contrast, compound 2 is an -diaurated species, in which the two gold atoms are coordinated in a linear
{
CH(PPh2NSiMe3)2
}
, with [(Ph3P)2CuI] afforded the
{
}
{
CH(PPh2NSiMe3)2
}
{
}
−
− − − −
R,R
fashion onto the ligand backbone. Photoluminescence measurements show that the latter compound has a strong
violet emission.
Scheme 1
Introduction
N,N-Bidentate monoanionic ligand systems1 such as ben-
zamidinates2 or aminotroponiminates3 have been used re-
cently in coordination chemistry to stabilize reactive metal
centers. Especially, â-diiminates (â-diketiminatos) (Scheme
1, A) became very popular as ligands for a number of metals
because they are known to support unusual metal oxidations
states4 and act as spectator ligands in catalysis.5,6 We and
others have recently been attracted by the bis(phosphinimi-
no)methanides ({CH(PPh2NR)2}-, R ) Mes, SiMe3) (Scheme
1, B), a P-N ligand system that is topologically related to
the â-diiminate ligands. The bis(phosphinimino)methanides
were used as ligands for a large number of metals ranging
from main group7-10 and transition metals11-17 to 4f18,19 and
5f20 metals. {CH(PPh2NSiMe3)2}- tends to show an uncom-
mon coordination mode. In most of the solid-state structures,
* To whom correspondence should be addressed. E-mail: roesky@
chemi.fu-berlin.de (P.W.R.). Office: 49 30-838-5440 (P.W.R). Fax: 49 30-
838-52440 (P.W.R.).
(7) (a) Gamer, M. T.; Roesky, P. W. Z. Anorg. Allg. Chem. 2001, 627,
877-881. (b) Panda, T. K.; Zulys, A.; Gamer, M. T.; Roesky, P. W.
J. Organomet. Chem. 2005, 690, 5078-5089.
† Freie Universita¨t Berlin.
(8) Hill, M. S.; Hitchcock, P. B. Chem. Commun. 2003, 1758-1759.
(9) (a) Kamalesh Babu, R. P.; Aparna, K.; McDonald, R.; Cavell, R. G.
Inorg. Chem. 2000, 39, 4981-4984. (b) Aparna, K.; McDonald, R.;
Fuerguson, M.; Cavell, R. G. Organometallics 1999, 18, 4241-4243.
(10) (a) Wei, P.; Stephan, D. W. Organometallics 2002, 21, 1308-1310.
(b) Wei, P.; Stephan, D. W. Organometallics 2003, 22, 601-604.
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Chem. 2004, 689, 722-730.
‡ Universita¨t Siegen.
(1) Review: (a) Britovsek, G. J. P.; Gibson, V. C.; Wass, D. F. Angew.
Chem. 1999, 111, 448-468; Angew. Chem., Int. Ed. 1999, 38, 428-
447. (b) Kempe, R. Angew. Chem. 2000, 112, 478-504; Angew.
Chem., Int. Ed. 2000, 39, 468-493.
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481. (b) Edelmann, F. T. Top. Curr. Chem. 1996, 179, 113-148.
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Roesky, P. W. In Inorganic Chemistry Highlights; Meyer, G.,
Naumann, D., Wesemann, L., Eds.; Wiley-VCH: Weinheim, Germany,
2002; pp 171-180.
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Cimpoesu, F. Angew. Chem. 2000, 112, 4444-4446; Angew. Chem.,
Int. Ed. 2000, 39, 4274-4276.
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Elsevier, C. J. Inorg. Chim. Acta 1995, 235, 77-88.
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2002 102, 3031-3066.
10.1021/ic060932p CCC: $33.50
Published on Web 08/09/2006
© 2006 American Chemical Society
Inorganic Chemistry, Vol. 45, No. 18, 2006 7503

Panda et al.
in resealable flasks. NMR spectra were recorded on a JNM-LA
400 FT-NMR spectrometer. Chemical shifts are referenced to
internal solvent resonances and reported relative to tetramethylsilane
and 85% phosphoric acid (31P NMR). Elemental analyses were
carried out with an Elementar Vario. K{CH(PPh2NSiMe3)2},7a
[(Ph3P)2CuI],26 and [Ph3PAuCl]27 were prepared according to
literature procedures.
the methine carbon atom coordinates via a long interaction
onto the metal atom.7-20 Thus, the six-membered metalla-
cycle (N1-P1-C1-P2-N2-M), which is formed by the
chelation of the two trimethylsilylimine groups to the metal
center, adopts a pseudo-boat conformation (Scheme 1, C).
Motivated by these results, we were interested to get some
insight into the coordination chemistry of the {CH(PPh2-
NSiMe3)2}- ligand in group 11 chemistry. Although the bis-
(phosphinimino)methanides have been widely used in transi-
tion-metal chemistry, there is, to the best of our knowledge,
no report about group 11 compounds. Even with the related
and much more common â-diiminate ligands21 and the
inorganic analogues [CH(EPPh2)2]- (E ) O, S),22,23 only a
few group 11 complexes have been reported. Herein, we
describe the synthesis of the copper compound [{CH(PPh2-
NSiMe3)2}CuPPh3] (1) and the dinuclear gold complex [(Ph3-
PAu)2{C(PPh2NSiMe3)2}] (2), which does not form a six-
membered metallacycle but instead has two gold atoms in
the backbone of the ligand. We also investigated the
luminescence of the gold complex because of the consider-
able interest in these properties24 due to the uncertainty of
the assignment of the excited states involved in the transi-
tions.25
Photoluminescence measurements at room temperature as well
as at 11 K were recorded on a Jobin-Yvon fluorescence spec-
trometer (Fluorolog 3) equipped with two 0.22 m double mono-
chromators (SPEX, 1680) and a 450 W xenon lamp. The emission
spectra were corrected for photomultiplier sensitivity, the excitation
spectra for lamp intensity, and both for the transmission of the
monochromators. Cooling to 11 K was achieved by the use of a
closed-cycle He cryostat (Janis Research Co., CCS-150).
[{CH(PPh2NSiMe3)2}CuPPh3] (1). THF (15 mL) was con-
densed at -196 °C onto a mixture of 300 mg (0.5 mmol) of K{CH-
(PPh2NSiMe3)2} and 358 mg (0.5 mmol) of [(Ph3P)2CuI]. The
mixture was stirred for 16 h at room temperature. The solvent was
then evaporated, and 15 mL of toluene was introduced. The solution
was filtered and concentrated. Pentane (10 mL) was layered on
the top. Crystals were obtained after 1 day. Yield: 150 mg (34%).
1H NMR (C6D6, 400 MHz, 25 °C): δ 0.21 (s, 18H, SiMe3), 1.97
(t, 1H, CH 2J(H,P) 4.0 Hz), 6.99-7.04 (m, Ph), 7.4 (br, Ph), 7.6-
7.87 (m, Ph). 31P{H} NMR (C6D6, 161.7 MHz 25 °C): δ 21.4
(PCP), 27.5 (PPh3). Anal. Calcd for C49H54N2P3Si2Cu (883.6): C,
66.60; H, 6.16; N, 3.18. Found: C, 65.71; H, 5.73; N, 2.91.
Experimental Section
[(Ph3PAu)2{C(PPh2NSiMe3)2}] (2). THF (15 mL) was con-
densed at -196 °C onto a mixture of 300 mg (0.5 mmol) of K{CH-
(PPh2NSiMe3)2} and 248 mg (0.5 mmol) of [Ph3PAuCl]. The
reaction vessel was covered with aluminum foil, and the reaction
mixture was stirred for 12 h at room temperature. The solvent was
then evaporated, and 15 mL of toluene was introduced. The solution
was filtered and concentrated. Pentane (10 mL) was layered on
the top. Crystals were obtained after 1 day. The crystals are light
General Considerations. All manipulations of air-sensitive
materials were performed with the rigorous exclusion of oxygen
and moisture in flame-dried Schlenk-type glassware either on a dual
manifold Schlenk line that was interfaced to a high vacuum
(1 × 10-4 Torr) line or in an argon-filled M. Braun glovebox. THF
was predried over Na wire and distilled under nitrogen from K
and benzophenone ketyl prior to use. Hydrocarbon solvents (toluene
and n-pentane) were distilled under nitrogen from LiAlH4. All
solvents for vacuum-line manipulations were stored in vacuo over
LiAlH4 in resealable flasks. Deuterated solvents were obtained from
Chemotrade Chemiehandelsgesellschaft mbH (all g99 atom % D)
and were degassed, dried, and stored in vacuo over a Na/K alloy
1
sensitive. Yield: 200 mg (27%). H NMR (C6D6, 400 MHz, 25
°C): δ 0.32 (s, 18H, SiMe3), 6.86-7.03 (m, 30H, Ph), 7.23-7.27
(m, 10H Ph), 8.59-8.65 (m, 10H, Ph). 31P{H} NMR (C6D6, 161.7
MHz 25 °C): δ 12.2 (t, 3J (P,P) 8.9 Hz), 37.7 (t, 3J (P,P) 8.9 Hz).
IR (KBr, cm-1): 3085(m), 3070(m), 3051(m), 3004(m), 2941(m),
2883(w), 1959(m), 1888(w), 1645(m), 1587(w), 1573(w), 1479-
(m), 1434(s), 1417(m), 1384(m), 1276(w), 1230(w), 1182(w), 1155-
(br), 1099(m), 1068(w), 1026(m), 997(br), 972(m), 925(s), 858(m),
823(m), 794(s), 744(s), 709(m), 692(s), 665(m). Anal. Calcd for
C67H68Au2N2P4Si2 (1475.2): C, 54.55; H, 4.64; N, 1.90. Found:
C, 55.05; H, 4.78; N, 1.93.
(14) (a) Ong, C. M.; McKarns, P.; Stephan, D. W. Organometallics 1999,
18, 4197-4208. (b) Wei, P.; Stephan, D. W. Organometallics 2002,
21, 1308-1310.
(15) Kasani, A.; Kamalesh Babu, R. P.; McDonald, R.; Cavell, R. G.
Organometallics 1999, 18, 3775-3777.
(16) Leung, W.-P.; So, C.-W.; Wang, J.-Z.; Mak, T. C. W. Chem. Commun.
2003, 248-249.
(17) Bibal, C. Pink, M.; Smurnyy, Y. D.; Tomaszewski, J.; Caulton, K. G.
J. Am Chem. Soc. 2004, 116, 2312-2313.
X-ray Crystallographic Studies of 1 and 2. Crystals of 1 and
2 were grown from toluene/pentane. Suitable crystals of both
compounds were covered in mineral oil (Aldrich) and mounted onto
a glass fiber. The crystals were transferred directly to the -73 °C
cold N2 stream of a Stoe IPDS 2T diffractometer. Subsequent
computations were carried out on an Intel Pentium IV PC.
(18) (a) Gamer, M. T.; Dehnen, S.; Roesky, P. W. Organometallics 2001,
20, 4230-4236. (b) Gamer, M. T.; Roesky, P. W. J. Organomet.
Chem. 2002, 647, 123-127. (c) Zulys, A.; Panda, T. K.; Gamer, M.
T.; Roesky, P. W. Chem. Commun. 2004, 2584-2585. (d) Panda, T.
K.; Zulys, A.; Gamer, M. T.; Roesky, P. W. Organometallics 2005,
24, 2197-2202. (e) Panda, T. K.; Benndorf, P.; Roesky, P. W. Z.
Anorg. Allg. Chem. 2005, 631, 81-84.
All structures were solved by the Patterson method (SHELXS-
9728). The remaining non-hydrogen atoms were located from suc-
cessive difference Fourier map calculations. The refinements were
carried out using full-matrix least-squares techniques on F, min-
(19) Hill, M. S.; Hitchcock, P. B. Dalton Trans. 2003, 4570-4571.
(20) Sarsfield, M. J.; Helliwell, M.; Collison, D. Chem. Commun. 2002,
2264-2265.
(21) (a) Honeybourne, C. L.; Webb, G. A. Chem. Commun. 1968, 739-
40. (b) Pellacanis, G. C. Inorg. Chim. Acta 1975, 12, L3-L4.
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(23) Alvarez, B.; Fernadez, E. J.; Gimeno, M. C.; Jones, P. G.; Laguna,
A.; Lopez de Luzuriaga, J. M. Polyhedron 1988, 17, 2029-2035.
(24) Forward, J. M.; Fackler, J. P., Jr.; Assefa, Z. Optoelectronic Properties
of Inorganic Compounds; Roundhill, M., Fackler, J. P., Jr., Eds.;
Plenum: New York, 1998.
(26) Barron, P. F.; Dyason, J. C.; Healy, P. C.; Engelhardt, L. M.;
Pakawatchai, C.; Patrick, V. A.; White, A. H. J. Chem. Soc., Dalton
Trans. 1987, 1099-1106.
(27) Brauer, G. Handbuch der pra¨paratiVen Anorganischen Chemie;
Ferdinand Enke Verlag: Stuttgart, Germany, 1981; Vol. 3.
(28) Sheldrick, G. M. SHELXS-97, Program for Crystal Structure Solution;
University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(25) Bowmaker, G. A. Gold: Progress in Chemistry, Biochemistry and
Technology; Schmidbaur, H., Ed.; Wiley: New York, 1999.
7504 Inorganic Chemistry, Vol. 45, No. 18, 2006

Reactions of K{CH(PPH2NSiMe3)2} with Group 11 Compounds
Table 1. Crystallographic Details of [{CH(PPh2NSiMe3)2}CuPPh3] (1)
and [(Ph3PAu)2{C(PPh2NSiMe3)2}] (2)a
1
2
formula
fw
C49H54CuN2P3Si2
883.57
C67H68Au2N2P4Si2
1475.23
space group
a (Å)
b (Å)
C2/c (No. 15)
40.955(2)
9.9826(4)
P1h (No. 2)
12.6423(5)
14.1578(5)
19.4929(7)
93.587(3)
91.235(3)
115.643(3)
3134.6(2)
2
c (Å)
22.7804(11)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
96.470(4)
9254.0(7)
8
1.268
Figure 1. Perspective ORTEP view of the molecular structure of 1.
Thermal ellipsoids are drawn to encompass a 50% probability level.
Hydrogen atoms are omitted for clarity.
density (g/cm3)
radiation
1.562
MoKR (λ ) 0.71073 Å) MoKR (λ ) 0.71073 Å)
0.663
integration
µ (mm-1
)
4.853
integration
62 112
absorp corr
Scheme 2
no. of reflns collected 43 780
no. of unique reflns
12 395 [Rint ) 0.0893]
16 801 [Rint ) 0.0577]
no. of observed reflns 8830
15 616
GOF on F2
1.092
0.0518; 0.1227
1.131
0.0294; 0.0707
R1b; wR2c
a All data collected at 200 K. b R1 ) ∑||Fo| - |Fc||/∑|Fo|. c wR2 )
2
2
2
{∑[w(Fo - Fc )2]/∑[w(Fo )2]}1/2
.
imizing the function (Fo - Fc)2, where the weight is defined as
Table 2. Selected Bond Lengths (Å) and Angles (deg) of
[{CH(PPh2NSiMe3)2}CuPPh3] (1)
2
2
4F0 /2(Fo ) and Fo and Fc are the observed and calculated structure
factor amplitudes using the program SHELXL-97.29 In the final
cycles of each refinement, all non-hydrogen atoms except the dis-
ordered atoms C35 and C36 in 2 were assigned to anisotropic tem-
perature factors. Carbon-bound hydrogen atom positions were
calculated and allowed to ride on the carbon to which they are
bonded assuming a C-H bond length of 0.95 Å. The hydrogen
atom contributions were calculated, but not refined. The final values
of refinement parameters are given in Table 1. The locations of
the largest peaks in the final difference Fourier map calculation as
well as the magnitude of the residual electron densities in each
case were of no chemical significance. Positional parameters, hy-
drogen atom parameters, thermal parameters, bond distances, and
angles have been deposited as Supporting Information. Crystal-
lographic data (excluding structure factors) for the structures report-
ed in this paper have been deposited with the Cambridge Crystallo-
graphic Data Centre as supplementary publications CCDC-612163
(1) and 612164 (2). Copies of the data can be obtained free of
charge on application to CCDC, 12 Union Road, Cambridge
CB21EZ, U.K. (fax: ((44) 1223-336-033; E-mail: deposit@
ccdc.cam.ac.uk).
bond lengths (Å)
bond angles (deg)
N1-Cu-N2
N1-Cu-C1
N2-Cu-C1
N1-Cu-P3
N2-Cu-P3
P3-Cu-C1
P1-C1-P2
Cu-N1
2.074(2)
2.058(2)
2.838(3)
2.1756(7)
1.719(3)
1.724(3)
1.587(2)
1.593(2)
100.21(9)
64.95(8)
66.45(8)
129.66(7)
130.09(7)
128.34(6)
120.4(2)
Cu-N2
Cu-C1
Cu-P3
C1-P1
C1-P2
N1-P1
N2-P2
at 0.22 ppm. The methine proton shows a triplet (1.98 ppm),
which is in the range of bis(phosphinimino)methanide
lanthanide dichloride compounds [{CH(PPh2NSiMe3)2}-
LnCl2]2 (δ 1.93 (Ln ) Y) and 1.97 (Ln ) Lu)).18a The
2J(H,P) coupling constant (4.0 Hz) of the methine proton is
observed. The signals of the phenyl protons are in the
1
expected range in the H NMR spectrum. In the 31P{1H}
NMR spectra, two signals are observed at 21.4 and 27.5 ppm
that represent two kinds of phosphorus atoms. No coupling
between the two signals is observed. The phosphorus atoms
of the {CH(PPh2NSiMe3)2}- ligand show chemical equiva-
lence in solution, and the chemical shift (21.4 ppm) is in
the range of corresponding lanthanide dichloride compounds
[{CH(PPh2NSiMe3)2}LnCl2]2 (20.4 (Ln ) Y) and 20.5 ppm
(Ln ) Lu)).18a The signal of the triphenylphosphine group
is in the expected range of 27.5 ppm.
The solid-state structure of 1 was investigated by single-
crystal X-ray diffraction (Figure 1). Compound 1 crystallizes
in the monoclinic space group C2/c, with eight molecules
in the unit cell. Data collection parameters and selected bond
lengths and angles are given in Tables 1 and 2. If the
{CH(PPh2NSiMe3)2}- ligand is considered to be a tridentate
donor, the copper center is four-coordinated. The {CH(PPh2-
NSiMe3)2}- ligand is almost symmetrically attached to the
center metal. A six-membered metallacycle (N1-P1-C1-
P2-N2-Cu) is formed by chelation of the two trimethyl-
silylimine groups to the copper atom, resulting in a twist
Results and Discussion
Transmetalation of the potassium methanide complex,
K{CH(PPh2NSiMe3)2}, with [(Ph3P)2CuI] in a 1:1 ratio
followed by extraction with toluene and crystallization from
toluene/pentane afforded the corresponding copper complex
[{CH(PPh2NSiMe3)2}CuPPh3] (1) as colorless crystals in
good yields (Scheme 2).30 The new complex has been
characterized by standard analytical/spectroscopic techniques,
and the solid-state structure was established by single-crystal
X-ray diffraction.
1
For compound 1, the H NMR spectrum shows a sharp
singlet for Me3Si groups of the {CH(PPh2NSiMe3)2}- ligand
(29) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure Refine-
ment; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(30) The bonding situation in the drawings of the ligand system in Schemes
1 and 2 is simplified for clarity.
Inorganic Chemistry, Vol. 45, No. 18, 2006 7505

Panda et al.
Scheme 3
boat conformation in which the central carbon atom (C1)
and the copper atom are displaced from the N2P2 least-
squares plane. The Cu-N and Cu-P bond distances are in
the expected range of Cu-N1 (2.074(2) Å), Cu-N2 (2.058-
(2) Å), and Cu-P3 (2.1756(7) Å) (e.g., Cu-N1 ) 2.121(6)
Å and 2.116(7) Å, and Cu-P ) 2.244(2) Å in cis-[Cu2(µ-
CN)(Phen)2(PPh3)2]2[C(CN)3]‚BF4‚2CH3CN (phen ) 1,10
phenanthroline)).31 The distance between the C1 and the
copper atom (2.838(3) Å) is remarkably longer than the usual
Cu-C distances (e.g., 1.916(2) Å in [Cy3PCuMe]);32 how-
ever, a tridentate coordination of the ligand is found, as in
earlier observations.7-19 Compared to the starting material,
one of the triphenylphosphine groups is detached from the
copper atom in the final product. It can be rationalized that
Cu(I) mostly favors a coordination number of four. From
the bond angles (N2-Cu-C1 ) 66.45(8)°, N1-Cu-C1 )
64.95(8)°, N1-Cu-P3 ) 129.66(7)°, and N2-Cu-P3 )
130.09(7)°), it is seen that the N2-Cu-C1 and N1-Cu-
C1 angles are much shorter than the perfect tetrahedral angle,
thus a distorted tetrahedral geometry due to the rigid ligand
is observed. The solid-state structure of 1 is consistent with
the NMR spectra in solution.
Figure 2. Perspective ORTEP view of the molecular structure of 2.
Thermal ellipsoids are drawn to encompass a 50% probability level.
Hydrogen atoms are omitted for clarity.
Table 3. Selected Bond Lengths (Å) and Angles (deg) of
[(Ph3PAu)2{C(PPh2NSiMe3)2}] (2)
bond lengths (Å)
bond angles (deg)
Au1-C1-Au2
Au1-Au2
3.0224(6)
2.105(2)
2.099(3)
2.2672(8)
2.2648(12)
1.553(3)
1.551(3)
1.783(3)
1.789(3)
91.93(10)
172.78(8)
173.41(8)
109.45(13)
114.02(14)
110.61(14)
107.76(13)
119.62(14)
Au1-C1
Au2-C1
Au1-P3
Au2-P4
N1-P1
N2-P2
C1-P2
C1-Au1-P3
C1-Au2-P4
P1-C1-Au1
P1-C1-Au2
P2-C1-Au1
P2-C1-Au2
P2-C1-P1
C1-P1
phosphorus is not in the range of compound 1 (21.4 ppm).
With respect to the starting material K{CH(PPh2NSiMe3)2}
(13.0 ppm), there is a highfield shift of only 0.8 ppm for
methandiide phosphorus of complex 2. The other two
phosphorus atoms from Ph3P groups also show a 6.7 ppm
downfield shift compared to the starting complex [Ph3PAuCl]
(31.0 ppm). The methandiide phosphorus atoms show a
3J(P,P) coupling of 8.9 Hz with two phosphorus atoms of
two Ph3P groups.
The solid-state structure of 2 was investigated by single-
crystal X-ray diffraction (Figure 2). Data collection param-
eters and selected bond lengths and angles are given in
Tables1 and 3. The solid-state structure of 2 is consistent
with the NMR spectra in solution. Instead of the expected
monoaurated species, a “carbenoid” derivative with a double
deprotonated bis(phosphinimino)methane is formed. More-
over, the gold atoms are not chelated by the N1-P1-C1-
P2-N2 backbone; instead, the expected almost-linear co-
ordination of the gold atoms is observed (C1-Au1-P3 )
172.78(8)° and C1-Au2-P4 ) 173.41(8)°). R,R-Diaurated
compounds were observed earlier. Geminal diaurated ring
systems derived from an aromatic hydrocarbon were first
discovered in the 1970s by Nesmeyanov et al. in attempts
to introduce gold substituents into ferrocene.33 It was shown
that after conventional monometalation to give [{(Ph3PAu)-
C5H4}Fe(C5H5)], the second ligand-backed electrophile Ph3-
PAu+ is attached to the same carbon atom to generate a
cationic species of the proposed formula [{1,1(Ph3PAu)2C5H4}-
Fe(C5H5)]+.34 Recently, Schmidbaur et al. showed that
To compare the coordination mode of the copper complex
1 with a corresponding gold compound, we reacted K{CH-
(PPh2NSiMe3)2} with [Ph3PAuCl] in THF at room temper-
ature to give the corresponding dinuclear gold complex
[(Ph3PAu)2{C(PPh2NSiMe3)2}] (2) after extraction with
toluene and crystallization from toluene/pentane (Scheme 3).
Compound 2 is an air-stable but light-sensitive compound
and has been characterized by standard analytical/spectro-
scopic techniques; the solid-state structure was established
1
by single-crystal X-ray diffraction. The H NMR spectrum
of the compound 2 shows a sharp singlet for the Me3Si
groups of the {C(PPh2NSiMe3)2}2- at 0.32 ppm. In contrast
1
to compound 1, the H NMR spectrum of complex 2 does
not show any signal corresponding to a methine proton,
which means that the proton, originally present at the methine
carbon of K{CH(PPh2NSiMe3)2}, has been deprotonated
during the reaction. The signals of the phenyl protons are
broadened in the 1H NMR spectrum and are in the expected
range. In the 31P{1H} NMR spectra, complex 2 shows two
triplets at 12.2 and 37.7 ppm for the {C(PPh2NSiMe3)2}2-
and Ph3P phosphorus atoms, respectively; thus both phos-
phorus atoms of the {C(PPh2NSiMe3)2}2- ligand and the two
phosphorus atoms of two Ph3P groups are chemically
equivalent in the solution. The chemical shift of methandiide
(31) Kamte, M. F.; Baumeister, U. Scha¨fer, W. Z. Anorg. Allg. Chem. 2003,
629, 1919-1924.
(32) Schaper, F.; Foley, S. R.; Jordan, R. F. J. Am. Chem. Soc. 2004, 126,
2114-2124.
(33) Perevalova, E. G.; Lemonovskii, D. A.; Grandberg, K. I.; Nesmeyanov,
A. N. Dokl. Akad. Nauk SSSR 1972, 93-96.
7506 Inorganic Chemistry, Vol. 45, No. 18, 2006

Reactions of K{CH(PPH2NSiMe3)2} with Group 11 Compounds
thiophen reacts with [Ph3PAu]BF4 to form the cation [2,2-
(Ph3PAu)2C4H3S]+.35 The Au‚‚‚Au distance in compound 2
of 3.0224(6) Å is longer than that in elemental gold (2.88
Å) and in [2,2-(Ph3PAu)2C4H3S]+ (2.8134(4) Å).35 The Au1-
C1-Au2 angle of 91.93(10)° is significantly smaller than
the normal tetrahedral angle but larger than in the thiophen
complex [2,2-(Ph3PAu)2C4H3S]+ (82.5(2)°),35 the ferrocenyl
complex [{1,1(Ph3PAu)2C5H4}Fe(C5H5)]BF4 (78(1)°),34
and the trifluorophenyl complex [C6H2F3(AuPPh3)2]BF4
(79.3(3)°).36 The Au-C bond distances of compound 2 are
in the expected range of Au1-C1 (2.105(2) Å) and Au2-
C1 (2.099(3) Å).37 In contrast to the example shown above,
which used the salt [Ph3PAu]BF4 as the aurating species,
we used [Ph3PAuCl] as the starting material. [Ph3PAuCl] is
transformed during the reaction via a salt metathesis into
the [Ph3PAu]+ cation. Because [Ph3PAu]+ is isolobal to H+,
compound 2 can be considered as being isolobal to CH2(PPh2-
NSiMe3)2.38
As a mechanism for the formation of compound 2, we
propose that in the first step, a monoaurated species of
composition [(Ph3PAu){CH(PPh2NSiMe3)2}] is formed that
then is deprotonated by an excess of K{CH(PPh2NSiMe3)2}
as byproduct CH2(PPh2NSiMe3)2 is isolated. So far, we have
not been able to isolate the monoaurated species. In a control
experiment, we could show that compound 2 is also formed
by reaction of Li2{C(PPh2NSiMe3)2} with 2 equiv of [Ph3-
PAuCl]. The carbenoid type ligand {C(PPh2NSiMe3)2}2- was
introduced by Cavell et al. into the coordination chemistry
of a series of transition metals.39 To the best of our knowl-
edge, this type of ligand usually coordinates in a chelating
fashion, thus forming either four-membered C1-P2-N2-M
or six-membered N1-P1-C1-P2-N2-M metallacycles.
Compound 2 shows a violet emission by irradiation with
a UV lamp. After some time, the emission color changes to
green, which can be explained by the decomposition of the
complex as a result of the UV radiation. Therefore, the
photoluminescence measurements were performed as fast as
possible and also very carefully using excitation radiation
at low intensity.
Figure 3. Emission (left, λex ) 28 600 cm-1) and excitation (right, λem
)
23 000 cm-1) spectra of 2 at room temperature (top) and 11 K (bottom).
nm (19 920 cm-1), and a small one at 661 nm (15 130 cm-1).
Additionally, a shoulder at about 564 nm (17 730 cm-1) is
visible. At 11 K, the shape is almost unchanged. The largest
maximum is slightly red-shifted by 1 nm (23 150 cm-1) and
the full width at half-maximum (fwhm) is decreased to about
1670 cm-1. The second maximum is shifted to higher energy
(484 nm, 20 660 cm-1) and the shoulder is now clearly
visible. The excitation spectra show three transitions, at 353
nm (28 300, 28 530 cm-1 at 11 K), 287 nm (34 900 cm-1),
and 256 nm (39 100 cm-1).
The thus-obtained excitation and emission spectra are
shown in Figure 3. The emission spectrum at room temp-
erature includes three maxima at 431 nm (23 200 cm-1), 502
(34) Nesmeyanov, A. N.; Perevalova, E. G.; Grandberg, K. I.; Lemenovskii,
D. A.; Baukova, T. V.; Afanasova, O. B. J. Organomet. Chem. 1974,
65, 131-144.
For the assignment, we recorded spectra of the starting
material CH2(PPh2NSiMe3)2 (not shown). At low tempera-
tures, a broad band with three maxima again at 502, 484,
and 661 nm was detected, together with an additional band
at 374 nm. Therefore, the respective transitions in the spectra
of 2 can be clearly assigned to ligand transitions and the
(35) Porter, K. A.; Schier, A.; Schmidtbaur, H. Organometallics 2003, 22,
4922-4927.
(36) Uso´n, R.; Laguna, A.; Ferna´ndez, E. J.; Media, A.; Jones, P. G. J.
Organomet. Chem. 1988, 350, 129-138.
(37) Schmidtbaur, H. In ComprehensiVe Organometallic Chemisty II; Abel,
E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon Press: Oxford,
1995; Vol. 3.
2+
(38) Hoffmann, R. Angew. Chem. 1982, 94, 725-738; Angew. Chem., Int.
one at 432 nm is due to Au2 units. The band at 374 nm
Ed. 2003, 21, 711-724.
2+
was not observed for 2, so a ligand-Au2 energy transfer
(39) (a) Kamalesh Babu, R. P.; McDonald, R.; Decker, S. A.; Klobukowski,
M.; Cavell, R. G. Organometallics 1999, 18, 4226-4229. (b) Cavell,
R. G.; Kamalesh Babu, R. P.; Kasani, A.; McDonald, R. J. Am. Chem.
Soc 1999, 121, 5805-5806. (c) Kamalesh Babu, R. P.; McDonald,
R.; Cavell, R. G. Chem. Commun. 2000, 481-482. (d) Kasani, A.;
Ferguson, M.; Cavell, R. G. J. Am. Chem. Soc. 2000, 122, 726-727.
(e) Lin, G.; Jones, N. D.; Gossage, R. A.; McDonald, R.; Cavell, R.
G. Angew. Chem. 2003, 115, 4188-4191; Angew. Chem., Int. Ed.
2003, 42, 4054-4057.
can be concluded in this case.
The emission energy in the present case is in a comparable
range to that of [Au2(dmb)(CN)2] (dmb ) 1,8-di-isocyano-
p-menthane; λem ) 456 nm, R(Au‚‚‚Au) ) 3.536 Å)40 but
remarkably different from that of [Au3(dmmp)2](ClO4)3
(dmmp ) bis(dimethylphosphinomethyl)methylphosphine;
Inorganic Chemistry, Vol. 45, No. 18, 2006 7507

Panda et al.
λem ) 580 nm, R(Au‚‚‚Au) ) 2.981(1), 2.962(1) Å)41 and
[Au3(dpmp)2](SCN)3 (dpmp ) bis(diphenylphosphino-
methyl)phenylphosphine; λem ) 600 nm, R(Au‚‚‚Au) )
3.0137(8), 3.0049(8) Å).42 Because the distance between the
gold ions in 2 is similar to that in the latter compounds, this
is obviously not the decisive criterion for the position of the
emission bands. Instead, the nature of the donor atoms may
have some influence on the emission energy. Whereas the
donor atoms are phosphorus atoms in the case of [Au3-
(dmmp)2](ClO4)3 and [Au3(dpmp)2](SCN)3, carbon atoms act
as donors in [Au2(dmb)(CN)2]. In compound 2, the donor
atoms are P as well as C atoms. We suggest that the negative
charge of the carbon atoms may be the most important factor
for the high-energy emission.
After some irradiation time, the spectra are changed. In
the emission spectrum now, a very broad band between 400
and 700 nm, including a maximum at about 520 nm, is
visible, in which the shape is comparable to the red part of
the emission spectrum. Additionally, a small band at about
375 nm could be observed. Therefore, it can be assumed
that the radiation-induced decomposition yielded the ligand
and a nonluminescence gold species.
Summary
In summary, we have shown that the reaction of the
potassium methanide complex, K{CH(PPh2NSiMe3)2}, with
[(Ph3P)2CuI] and [Ph3PAuCl] leads to two different products.
The reaction of the copper compound resulted in [{CH(PPh2-
NSiMe3)2}CuPPh3], in which the bis(phosphinimino)-
methanide ligand forms the expected six-membered metal-
lacycle (N1-P1-C1-P2-N2-Cu). The metallacycle has
a twist boat conformation, in which the central carbon atom
(C1) and the copper atom are displaced from the N2P2 least-
squares plane. In contrast, the reaction with [Ph3PAuCl] gave
the diaurated gold complex [(Ph3PAu)2{C(PPh2NSiMe3)2}],
in which the two gold atoms are coordinated in a linear
fashion onto the ligand backbone. The latter compound
shows a strong violet emission, in which the largest band at
432 nm could be assigned to the gold dimer.
Acknowledgment. This work was supported by the
Deutsche Forschungsgemeinschaft (DFG). Umicore AG &
Co. KG is acknowledged for the donation of HAuCl4.
Supporting Information Available: X-ray crystallographic files
in CIF format for the structure determinations of 1 and 2. This
material is available free of charge via the Internet at http://
pubs.acs.org.
(40) Che, C.-M.; Wong, W.-T.; Lai, T.-F.; Kwong, H.-L. J. Chem. Soc.,
Chem. Commun. 1989, 243.
(41) Yam, V. W.-W.; Lai, T.-F.; Che, C.-M. J. Chem. Soc., Dalton Trans.
1990, 3747-3752.
(42) Li, D.; Che, C.-M.; Peng, S.-M.; Liu, S.-T.; Zhou, Z.-Y.; Mak, T. C.
W. J. Chem. Soc., Dalton Trans. 1993, 189-194.
IC060932P
7508 Inorganic Chemistry, Vol. 45, No. 18, 2006