Copper(I) and gold(I) complexes with N,N′-bis(diphenylphosphino)-2,6- diaminopyridine as ligand: Synthesis and molecular structures

Article abstract of DOI:10.1002/zaac.200500335

Reaction of CuI with 1 or 2 equivalent(s) N,N′-Bis(diphenylphosphino) -2,6-diaminopyridine (BDDP) gives two different complexes, [Cu(I)μ-(BDDP- κP,N_py)]₂ (1) and [Cu(BDDP-κP,N _py)₂]I (2), in high yields. The determination of the molecular structure show that both Cu^I atoms are tetrahedrally coordinated, rather than a square-planar geometry reported for Cr⁰, Ni^II-BDDP complexes before, which contains a planar tridentate chelate ring system. The introduction of AuCl(tht) (tht = tetrahydrothiophene) into [Cu(BDDP-κP,N_py)₂]I leads unexpectedly to the formation of a digold complex 2,6-[(ClAuPh₂P)HN]₂C ₅H₃N and dimeric [Cu(I)μ-(BDDP-κP,N _py)]₂.

Full text of DOI:10.1002/zaac.200500335

DOI: 10.1002/zaac.200500335
Copper(I) and Gold(I) Complexes with N,NЈ-Bis(diphenylphosphino)-2,6-
diaminopyridine as Ligand: Synthesis and Molecular Structures
Zhida Pan, Michael T. Gamer, and Peter W. Roesky*
Berlin, Institut für Chemie und Biochemie der Freien Universität
Received August 15th, 2005.
Dedicated to Professor Kurt Dehnicke on the Occasion of his 75th Birthday
Abstract. Reaction of CuI with 1 or 2 equivalent(s) N,NЈ-Bis(di-
phenylphosphino)-2,6-diaminopyridine (BDDP) gives two different
complexes, [Cu(I)µ-(BDDP-κP, N py)]2 (1) and [Cu(BDDP-κP, N py)2]I
(2), in high yields. The determination of the molecular structure
show that both CuI atoms are tetrahedrally coordinated, rather
than a square-planar geometry reported for Cr0, NiII-BDDP com-
plexes before, which contains a planar tridentate chelate ring
system. The introduction of AuCl(tht) (tht ϭ tetrahydrothiophene)
into [Cu(BDDP-κP, N py)2]I leads unexpectedly to the formation of a
digold complex 2,6-[(ClAuPh2P)HN]2C5H3N and dimeric [Cu(I)µ-
(BDDP-κP, N py)]2.
Keywords: Phosphinoamine; N,P Ligand; Copper; Gold
Introduction
In principal, the central metal atoms of different soft and
hard Lewis acidity usually need to be satisfied in a most
suitable fashion, in hence heterodentate ligands have the
most possibility to form multinuclear complexes [1]. Among
these, phosphinoamine ligands are of increasing interest in
synthetic inorganic and organometallic chemistry [2], due
to its significantly high flexibility in coordination, both N,P
elements are extensively used as ’docking spot’, and the
steric and electronic effects of electron-donating atoms as
well as the bridging unit could be tuned over wide limits [3].
Recently there have been many research efforts by us and
others in developing phosphinoamide chemistry of the tran-
sition metals, such as monophosphanylamides (R2PNRЈ)
(A) [4, 5, 6, 7], diphosphanylamides ((Ph2P)2N) (B) [5, 8, 9],
phosphoraneiminato (R3PN) (C) [10], phosphiniminome-
thanides ((RNPRЈ2)CH) (D) [11, 12, 13, 14, 15, 16]. N,NЈ-
Bis(diphenylphosphino)-2,6-diaminopyridine (BDDP) (E)
was first introduced by Haupt et al. with the neutral car-
bonyl compounds of chromium family, and also MCl2 (Mϭ
Ni, Pd, Pt) in 1987 [17, 18]. Some lanthanide complexes
have been prepared [19], however its coordination behav-
iour with late transition metals is still far beyond under-
stand. The d10 ions of the coinage metals demonstrate vari-
able coordination geometry, for example, CuI and AgI are
Scheme 1 Some selected aminophosphane ligands
predominantly found as tetrahedral species, while AuI ap-
pears essentially in a linear molecule with coordination
number 2, even if the ligand is ideal to form a trigonal
planar or tetrahedral species [20]. In this paper we describe
the synthesis of copper(I) complexes with BDDP and the
unexpected results when trying to introduce a second metal,
gold(I) or cobalt(II), into the molecular frame.
* Prof. Dr. Peter W. Roesky
Institut für Chemie und Biochemie
Freie Universität Berlin
Fabeckstraße 34-36, 14195 Berlin (Deutschland)
Fax: (ϩ49)30-838-52440
Results and Discussion
The rigid N,NЈ-bis(diphenylphosphino)-2,6-diaminopyri-
dine (BDDP) was studied as a multifunctional ligand in co-
e-mail: roesky@chemie.fu-berlin.de
744
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2006, 632, 744Ϫ748

Copper(I) and Gold(I) Complexes
Scheme 2 Synthesis of [Cu(I)BDDP]2 (1) and [Cu(BDDP-κP, N py)2]I (2)
The treatment of CuI with equal molar BDDP in THF
afforded the dimer [Cu(I)µ-(BDDP-κP, N py)]2 (1) in good
yield. The solid state structure of compound 1 was estab-
lished by single crystal X-ray diffraction (Figure 1). Com-
pound 1 crystallizes in the monoclinic space group P21/n
with four molecules in the unit cell. In compound 1 each
copper atom is tetrahedrally coordinated by the pyridine
nitrogen and one chelating phosphorus atom from one li-
gand, a phosphorus atom from another ligand, and one
iodine atom to balance the charge. The corresponding
31P{1H} NMR spectrum shows a sharp singlet at δ ϭ 27.3
indicating that all of the phosphorus atoms are chemically
equivalent. An ESI ϪMS spectrum recorded from 1 dis-
solved in DMSO does not show any sign of decomposition
in solution. The peak with the highest intensity could be
assigned to the fragment [Cu2(I)(BDDP-κP, N py)2]ϩ. The
bond lengths of Cu1-P1 and Cu1-P4 are very similar,
225.53(10) pm and 225.56(10) pm, respectively, while the
distances of Cu2-P2 and Cu2-P3 are slightly different,
224.87(10) pm and 226.06(11) pm. The other bond lengths,
such as Cu-N and Cu-I are symmetrically equal and fall
well in the expected regions [21]. Both of the amine nitrogen
atoms have not taken part in the coordination.
Fig. 1 Solid-state structure of 1 showing the atom labeling
scheme, omitting hydrogen atoms. Selected bond lengths/pm and
bond angles/° include:
Cu1-P1 225.53(10), Cu1-P4 225.56(10), Cu1-N1 216.2(3), Cu1-I1 260.10(5),
Cu2-P2 224.87(10), Cu2-P3 226.06(11), Cu2-N4 214.9(3), Cu2-I2 260.84(5),
I1-Cu1-P1 120.52(3), I1-Cu1-P4 109.60(3), I1-Cu1-N1 102.49(8), P1-Cu1-N1
84.66(8), P1-Cu1-P4 123.84(4), P4-Cu1-N1 108.60(8), N2-P1-Cu1 97.59(11),
I2-Cu2-P3 115.76(3), I2-Cu2-P2 112.47(3), I2-Cu2-N4 98.53(8), P3-Cu2-N4
83.90(8), P3-Cu2-P2 125.84(4), P2-Cu2-N4 111.97(8), N5-P3-Cu2 98.49(12).
Since all phosphorus atoms are already chemically
bonded in 1, a new compound containing two BDDP li-
gands, [Cu(BDDP-κP, N py)2]I (2), have been prepared, in
order to obtain more vacant coordinating sites. Compound
2 crystallizes in the monoclinic space group P21/n having
four molecules of 2 in the unit cell. The structure of com-
pound 2 was solved but as a result of the poor quality of
the crystal could not be fully refined. Since the quality of
the refinement is low only the lattice constants but no de-
tailed discussion is presented. The central metal in 2 is like
in 1 tetrahedrally coordinated by the two pyridine nitrogens
ordination chemistry with [M(CO)3(CH3CN)3] (MϭCr,
Mo, W) and MCl2 (M ϭ Ni, Pd and K2PtCl4 as the source
of Pt) [17]. In both cases, the determined molecular struc-
tures show a nearly planar tridentate chelating ring system,
namely two fused five-member rings docking by phos-
phorus atoms and pyridine nitrogen. We were interested to
study the BDDP ligand in the coordination chemistry of
the coinage metals. One goal was to obtain with the hetero-
dentate phosphanylamine multinuclear complexes, which
tend to contain some metal-metal interactions.
Z. Anorg. Allg. Chem. 2006, 744Ϫ748
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
745

Z. Pan, M. T. Gamer, P. W. Roesky
Fig. 3 Solid-state structure of 3 showing the atom labeling
scheme, omitting hydrogen atoms. Selected bond lengths/pm and
bond angles/° include:
Au1-P1 222(3), Au1-Cl1 237(3), P1-N1 168(4), Au2-P2 222(3), Au2-Cl2
239(3), P2-N3 170(4), P1-Au1-Cl1 176.78(2), P2-Au2-Cl2 177.81(2).
Fig. 2 Solid-state structure of 2 showing the atom labeling
scheme, omitting hydrogen atoms.
Cl are nearly linear with angles of 176.78(2) and 177.81(2).
31P{1H} NMR spectrum of 3 in d8-THF shows a sharp
singlet with chemical shift at 56.3 ppm.
Because of the fast coordinating equilibrium between the
four phosphorus donors, it is reasonable to have two AuCl
lunched on the same ligand simultaneously. However, so far
it could not be explained the ’driving force’ to reach the
final product. AuI complex usually adopts linear coordi-
nation geometry, and apparently there is no steric problem
for the heterometallic intermediate. A NMR tube-scale re-
action of 2 and AuCl(tht) in 1:2 ratio in d6-DMSO does
not lead to clear results of the mechanism.
and two chelating phosphorus atoms from each ligand (Fig-
ure 2). Slightly different from 1, the iodine acts as a non-
coordinating counter anion and the structure suggests there
is a possible hydrogen bond interaction between the iodine
and one close amino group.
An ESIϪMS spectrum recorded from 2 dissolved in
DMSO does not show any sign of decomposition in solu-
tion. The molecular peak of the [Cu(BDDP-κP, N py)2]ϩ
could be clearly detected. The 31P{1H} NMR spectrum in
d6-DMSO shows two very close singlets at 16.3 and
17.2 ppm, respectively, the chemical shifts move towards a
higher field than 1 (27.3 ppm). There is no obvious signal
for the two non-coordinating phosphorus atoms and the
nearly identical chemical shifts on the 31P{1H} spectrum
could possibly explained by a fast coordinating equilibrium
between these four phosphorous atoms in the solution. As
a result of the high melting point of DMSO low tempera-
ture VT NMR spectra cannot be recorded. Compared with
Experimental
All manipulations of air- and moisture-sensitive complexes were
carried out under an atmosphere of Argon using standard
Schlenk-lines or glove box techniques. Solvents were dried accord-
ing to standard methods and collected by distillation. BDDP was
prepared according to literature method [17], purified by recrystal-
lization from toluene/pentane (1:7) and checked by NMR measure-
ments. AuCl(tht) was prepared according to a similar synthetic
1
1, the H spectrum of 2 shows a broad aromatic proton
1
route for AuCl(PPh3) [23]. H and 31P{1H} NMR spectra were re-
signal with a few splitting fine structures.
corded on JNM-LA 400 FT-NMR spectrometer. Chemical shifts
are referenced to tetramethylsilane and 85 % phosphoric acid
(31P{1H} NMR). Elemental analysis was conducted on an Ele-
mentar vario EL. Mass spectra were taken on a Fourier transform
ion cyclotron resonance (FT-ICR) mass spectrometer (Bruker Dal-
tonics, APEX II) equipped with a 7T magnet and an electrospray
ionization source (Analytica of Branford) with a home-built rf ion
optics for improved sensitivity. Solutions from 1 and 2 in DMSO
were prepared and sprayed using nitrogen as nebulizing gas at a
flow rate of 300 µl/h. The desolvation capillary was typically heated
to about 80 °C.
Next we tried to coordinate another kind of metal to the
non coordinating phosphorus atoms of 2. After the ad-
dition of two equivalents of AuCl(tht) (tht ϭ tetrahydro-
thiophene), the solution turned into yellow immediately. X-
ray suitable single crystals were grown from the mother
solution directly after the following filtration and concen-
tration. To our surprise, it forms a digold(I) complex, [2,6-
{(ClAuPh2P)NH}2C5H3N] (3), rather than a heterometallic
compound as expected (Figure 3). The crystal data of 3
revealed the structure reported by Dyson et al. in 2004 [22],
which contains only different solvent molecules. The mol-
ecule has slight shorter distances between gold and phos-
phorus, namely 222(3) pm for Au1-P1 and 222(3) pm for
Au2-P2; and longer Au-Cl bonds, 237(3) pm for Au1-Cl1
and 239(3) pm for Au2-Cl(2). Both the fragments of P-Au-
Synthesis of [Cu(I)µ-(BDDP-κP,Npy)]2 (1):
20 ml THF was condensed at Ϫ196 °C into a mixture of 0.06 g
CuI (0.315 mmol) and 0.15 g BDDP (0.315 mmol). The reaction
746
www.zaac.wiley-vch.de
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2006, 744Ϫ748

Copper(I) and Gold(I) Complexes
mixture was allowed to warm to room temperature and kept
stirring until the dust of CuI disappeared gradually. After
filtration, the pale green solution was concentrated to 10 ml under
vaccum, and the product was obtained as white block crystalline
after days, 0.206 g (77 % in yield). Elemental analysis for
C58H50N6P4Cu2I2·4THF (1624.29), calcd. C,54.71, H,5.09, N,5.17;
found C,54.06, H,4.63, N,5.12 %.
independent reflections measured, of which 12752 were considered
observed with I > 2σ(I); max. residual electron density 1.022 and
Ϫ0.829 e/AϪ3; 713 parameters (all non hydrogen atoms were calcu-
lated anisotropic; the positions of the H atoms were calculated for
idealised positions) R1 ϭ 0.0528; wR2 ϭ 0.1024 (all data).
GOOF ϭ 1.043.
IR (KBr/cmϪ1): 3187 (s), 3050 (m), 1599 (s), 1576 (vs), 1454 (vs), 1433 (m),
1323 (m), 1231 (m), 1162 (m), 1097 (s), 1047 (m), 1033 (s), 998 (m), 971 (s),
819 (m), 781 (m), 737 (s), 694 (s), 512 (m). 1H NMR (d6-DMSO, 400 MHz,
25 °C): δϭ7.20-8.52 (multi and broad, 23H, aromatic H), 6.18, (s, NH), 1.74,
3.59 ppm (s, THF). 31P{1H} NMR (d6-DMSO, 161.7 MHz, 25 °C): δ ϭ 27.3
(s). ESI/MS: m/z (%): 1874 ([M ϩ [Cu(BDDP-κP, N py)]]ϩ, rel. int. 4), 1207
([MϪI]ϩ, 100), 1017 (5), 833 ([Cu(BDDP-κP, N py)2]ϩ, 43), 540 ([Cu(BDDP-
κP, N py)]ϩ, 40).
2: C58H39N6P4CuI, monoclinic space group P21/n (no.14); lattice
constants a ϭ 1953.47(3), b ϭ 1220.02(2), c ϭ 2318.48(4) pm, β ϭ
106.14(1)°, V ϭ 5307.7(2) 106 pm3.
¯
3: C70H74N6O3P4Cl4Au4, triclinic, P1 (no.2), a ϭ 1003.7(2), b ϭ
1282.2(2), c ϭ 1530.7(3) pm, Ͱ ϭ 65.90(3), β ϭ 78.04(3), γ ϭ
83.15(3)°; V ϭ 1757.84(25) 106 pm3, Z ϭ 1, µ(Mo-Kα) ϭ
8.614 mmϪ1; θmax. ϭ 29.24°; 9389 (Rint ϭ 0.0392) independent re-
flections measured, of which 6594 were considered observed with
Synthesis of [Cu(BDDP-κP,Npy)2]I (2):
I > 2σ(I); max. residual electron density 2.895 and Ϫ2.519 e/AϪ3
;
380 parameters (all non hydrogen atoms were calculated aniso-
tropic; the positions of the H atoms were calculated for idealised
positions) R1 ϭ 0.0364, wR2 ϭ 0.0938(all data), GOOF ϭ 0.899.
20 ml THF was condensed at Ϫ196 °C into a mixture of 0.06 g
CuI (0.315 mmol) and 0.3 g BDDP (0.629 mmol). The mixture was
stirred for 2 hours at room temperature, and the suspension of CuI
disappeared gradually during this period. After filtration, the pale
green solution was concentrated to 10 ml under vaccum, and the
product was obtained as white block crystalline after days, 0.283 g
(79 % in yield). Elemental analysis for C58H50N6P4CuI (1145.42),
calcd. C,60.82, H,4.40, N,7.34; found C,60.17, H,4.09, N,7.25 %.
IR (KBr/cmϪ1): 3343 (w), 3321 (w), 3314 (m), 3068 (m), 1602 (s), 1573 (vs),
1476 (vs), 1344 (m), 1317 (vs), 1228 (w), 1170 (m), 1161 (s), 1097 (s), 1068
(s), 1032 (s), 998 (m), 971 (s), 913 (s), 867 (m), 781 (m), 737 (s), 696 (s), 690
(s) 518 (s), 504 (s). 1H NMR (d6-DMSO, 400 MHz, 25 °C): δ ϭ 6.80-7.70
(b, 23H, aromatic H), 6.05-6.40 (m, 2H, NH). 31P{1H} NMR (d6-DMSO,
161.7 MHz, 25 °C): δ ϭ 16.3, 17.2 (s). ESI/MS: m/z (%): 1017 ([Cu(BDDP-
κP, N py)2]ϩ, rel. int. 60), 833 ([Cu(BDDP-κP, N py)2]ϩ, 43), 540 ([Cu(BDDP-
κP, N py)]ϩ, 100).
Crystallographic data (excluding structure factors) for the struc-
tures reported in this paper have been deposited with the Cam-
bridge Crystallographic Data Centre as a supplementary publi-
cation no. CCDC-275264 (1) and 275265 (3). Copies of the data
can be obtained free of charge on application to CCDC, 12 Union
Road, Cambridge CB21EZ, UK (fax: (ϩ(44)1223-336-033; email:
mailto:deposit@ccdc.cam.ac.uk).
Acknowledgement. Financial support from the Alexander von
Humboldt-Stifung for Dr. Zhida Pan is gratefully appreciated.
Umicore AG & Co. KG is acknowledged for the donation of
HAuCl4. Dr. Oliver Hampe and Dr. Olaf Fuhr (Karlsruhe) are
acknowledged for recording ESI-MS Spectra.
Synthesis of [2,6-{(ClAuPh2P)HN}2C5H3N] (3):
0.2 g AuCl(tht) (0.625 mmol) was added to the THF solution of
[Cu(I)µ-(BDDP-κP, N py)]2 (0.315 mmol) prepared above without
any further isolation. The reaction mixture was shielded with alu-
minium foil and stirred overnight. After filtration, the yellow solu-
tion was concentrated to 10 ml, and the digold complex, 3 was
obtained as colourless block crystalline after days, 0.081 g (48 % in
yield). Elemental analysis for C29H25N3P2Au2Cl2·1.5THF
(2100.97), calcd. C,40.02, H,3.55, N,4.00; found C,40.33, H,3.50,
N,3.74 %. (AuCl)2BDDP is also possibly prepared by the direct re-
action of AuCl(tht) and BDDP in a 2:1 molar ratio in THF.
References
[1] a) R. Kempe, H. Noss, T. Irrgang, J. Organomet. Chem. 2002,
647, 12. b) N. Wheatley, P. Kalck, Chem. Rev. 1999, 99, 3379.
´
´
c) R. Fandos, C. Hermandez, A. Otero, A. Rodrıguez, M. J.
Ruiz, P. Terreros, Chem. Eur. J. 2003, 9, 671.
[2] a) M. Knorr, C. Strohmann, Eur. J. Inorg. Chem. 1998, 495.
b) S.Wingerter, M. Pfeiffer, A. Murso, C. Lustig, T. Stey, V.
Chandrasekhar, D. Stalke, J. Am. Chem. Soc. 2001, 123, 1381.
[3] M. S. Balakrishna, V. S. Reddy, S. S. Krishnamurthy, J. C. T.
R. Burckett St. Laurent, Coord. Chem. Rev. 1994, 129, 1Ϫ90.
[4] D. Fenske, B. Maczek, K. Maczek, Z. Anorg. Allg. Chem.
1997, 623, 1113.
[5] O. Kühl, T. Koch, F. B. Somoza, P. C. Junk, E. Hey-Hawkins,
D. Plat, M. S. Eisen, J. Organomet. Chem. 2000, 604, 116.
[6] O. Kühl, P. C. Junk, E. Hey-Hawkins, Z. Anorg. Allg. Chem.
2000, 626, 1591.
1H NMR (d8-THF, 400 MHz, 25 °C): δ ϭ 6.50-8.20 (m, aromatic H), 6.50
(br. NH). 31P{1H} NMR (d8-THF, 161.7 MHz, 25 °C): δ ϭ 56.3 (s).
X-ray Crystallographic Studies of 1, 2 and 3.
Crystals of 1 were obtained from THF/ n-pentane (1:4). Crystals
of 2 and 3 were grown from THF. A suitable crystal was covered
in mineral oil (Aldrich) and mounted onto a glass fiber. The crystal
was transferred directly to the Ϫ100 °C cold N2 stream of a Stoe
IPDS2T diffractometer. Subsequent computations were carried out
on an Intel Pentium IV PC.
[7] a) T. G. Wetzel, S. Dehnen, P. W. Roesky, Angew. Chem. 1999,
111, 1155; Angew. Chem., Int. Ed. 1999, 38, 1086. b) S.
Wingerter, M. Pfeiffer, F. Baier, T. Stey, D. Stalke, Z. Anorg.
Allg. Chem. 2000, 626, 1121.
Data collection and refinement: SHELXS-97 [24], SHELXL-97;
[25] 1: C70H74N6O3P4Cu2I2, monoclinic space group P21/n (no.14);
[8] P. W. Roesky, M. T. Gamer, M. Puchner, A. Greiner, Chem.
Eur. J. 2002, 8, 5265.
lattice constants
a
ϭ
2409.14(9),
b
ϭ
1256.86(4),
c
ϭ
[9] a) P. Braunstein, J. Durand, G. Kickelbick, M. Knorr, X.
Morise, R. Pugin, A. Tiripicchio, F. Ugozzoli, Dalton Trans.
1999, 4175. b) M. Knorr, C. Strohmann, Organometallics
2487.44(10) pm, β ϭ 117.07(0)°, V ϭ 6706.74(10) 106 pm3, Z ϭ 4;
µ(Mo-Kα) ϭ 1.701 mmϪ1; θmax. ϭ 29.29°; 18094 (Rint ϭ 0.0741)
Z. Anorg. Allg. Chem. 2006, 744Ϫ748
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
747

Z. Pan, M. T. Gamer, P. W. Roesky
1999, 18, 248. c) P. Braunstein, J. Cossy, M. Knorr, C.
Strohmann, P. Vogel, New J. Chem. 1999, 23, 1215.
[10] For reviews see: a) K. Dehnicke, F. Weller, Coord. Chem. Rev.
1997, 158, 103. b) K. Dehnicke, M. Krieger, W. Massa, Coord.
Chem. Rev. 1999, 182, 19.
[11] P. Imhoff, J. H. Guelpen, K. Vrieze, W. J. J. Smeets, A. L.
Spek, C. J. Elsevier, Inorg. Chim. Acta 1995, 235, 77.
[12] a) M. W. Avis, M. E. van der Boom, C. J. Elsevier, W. J. J.
Smeets, A. L. Spek, J. Organomet. Chem. 1997, 527, 263. b)
M. W. Avis, C. J. Elsevier, J. M. Ernsting, K. Vrieze, N. Veld-
man, A. L. Spek, K. V. Katti, C. L. Barnes, Organometallics
1996, 15, 2376. c) M. W. Avis, K. Vrieze, H. Kooijman, N.
Veldman, A. L. Spek, C. J. Elsevier, Inorg. Chem. 1995, 34,
4092. d) P. Imhoff, R. van Asselt, J. M. Ernsting, K. Vrieze,
C. J. Elsevier, W. J. J. Smeets, A. L. Spek, A. P. M. Kentgens,
Organometallics 1993, 12, 1523.
[15] G. Aharonian, K. Feghali, S. Gambarotta, G. P. A. Yap,
Organometallics 2001, 20, 2616.
[16] M. T. Gamer, P. W. Roesky, Z. Anorg. Allg. Chem. 2001, 627,
877.
[17] W. Shirmer, U. Flörke, H. J. Haupt, Z. Anorg. Allg. Chem.
1987, 545, 83.
[18] W. Shirmer, U. Flörke, H. J. Haupt, Z. Anorg. Allg. Chem.
1989, 574, 239.
[19] M. Rastätter, P. W. Roesky unpublished work.
[20] M. A. Carvajal, J. J. Novoa, S. Alvarez, J. Am. Chem. Soc.
2004, 126, 1465.
[21] M. L. Engelhardt, P. C. Healy, J. D. Kildea, A. H. White, Aust.
J. Chem. 1989, 42, 913.
[22] N. Biricik, Z. F. Fei, R. Scopelliti, P. J. Dyson, Eur. J. Inorg.
Chem. 2004, 4232.
[23] B. J. Gregory, C. K. Ingold, J. Chem. Soc. B 1969, 276.
[24] G. M. Sheldrick SHELXS-97, Program of Crystal Structure
Solution, University of Göttingen, Germany, 1997.
[25] G. M. Sheldrick, SHELXL-97 Program of Crystal Structure
Solution, University of Göttingen, Germany, 1997.
[13] C. M. Ong, P. McKarns, D. W. Stephan, Organometallics 1999,
18, 4197.
[14] M. T. Gamer, S. Dehnen, P. W. Roesky, Organometallics 2001,
20, 4230.
748
www.zaac.wiley-vch.de
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2006, 744Ϫ748