Synthesis and structural characterization of Groups 10 and 11 mononuclear fluoroaryloxide complexes

Article abstract of DOI:10.1016/j.poly.2005.06.012

A study of four late-transition metal fluoroaryloxide (OAr^F or OAr′) complexes is presented including X-ray crystallography, polynuclear solution NMR spectroscopy, UV-Vis spectroscopy and elemental analyses. The study includes three new compounds: [(Ph₃P)₂Ni(OAr ^F)₂] (1a), [(Ph₃P)₂Ni(OAr′) ₂] (1b), [(COD)Pt(OAr^F)₂] (2) and one compound whose synthesis and elemental analysis were reported previously: [(Ph ₃P)Au(OAr^F)] (3). These compounds represent the common L₂MX₂ (1a, 1b, 2) and LMX (3) ligand classes in Groups 10 and 11, respectively, but with an uncommon ligand type, the monodentate phenoxide. In the solid state, compounds 1a and 1b exhibit square-planar geometry at nickel with trans phosphines in each case. In solution, these nickel compounds slowly decompose in CH₂Cl₂. Compound 2 is quite stable in solution at room temperature with the two phenoxide ligands cis to one another in the solid state. Compound 3 has a virtually linear geometry at the gold center and is stable in the solid state in the dark but decomposes slowly in solution in the light. Comparison of these four fluoroaryloxide compounds with the protio analogs (or attempts to make such compounds) demonstrate the greater stability to reduction of late-metal aryloxide complexes with highly electron-withdrawing substituents on the phenoxide rings.

Full text of DOI:10.1016/j.poly.2005.06.012

Polyhedron 24 (2005) 1803–1812
www.elsevier.com/locate/poly
Synthesis and structural characterization of Groups 10 and
11 mononuclear fluoroaryloxide complexes
a
b
b
a,
*
Miki Kim , Lev N. Zakharov , Arnold L. Rheingold , Linda H. Doerrer
a
Barnard College, Chemistry Department, 3009 Broadway, New York, NY 10027, United States
Department of Chemistry and Biochemistry, MC 0358, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, United States
b
Received 8 September 2004; accepted 14 June 2005
Available online 27 July 2005
Dedicated to Prof. Malcolm L.H. Green
Abstract
A study of four late-transition metal fluoroaryloxide (OArF or OAr0) complexes is presented including X-ray crystallography,
polynuclear solution NMR spectroscopy, UV–Vis spectroscopy and elemental analyses. The study includes three new compounds:
[(Ph3P)2Ni(OArF)2] (1a), [(Ph3P)2Ni(OAr0)2] (1b), [(COD)Pt(OArF)2] (2) and one compound whose synthesis and elemental analysis
were reported previously: [(Ph3P)Au(OArF)] (3). These compounds represent the common L2MX2 (1a, 1b, 2) and LMX (3) ligand
classes in Groups 10 and 11, respectively, but with an uncommon ligand type, the monodentate phenoxide. In the solid state, com-
pounds 1a and 1b exhibit square-planar geometry at nickel with trans phosphines in each case. In solution, these nickel compounds
slowly decompose in CH2Cl2. Compound 2 is quite stable in solution at room temperature with the two phenoxide ligands cis to one
another in the solid state. Compound 3 has a virtually linear geometry at the gold center and is stable in the solid state in the dark
but decomposes slowly in solution in the light. Comparison of these four fluoroaryloxide compounds with the protio analogs (or
attempts to make such compounds) demonstrate the greater stability to reduction of late-metal aryloxide complexes with highly
electron-withdrawing substituents on the phenoxide rings.
Ó 2005 Elsevier Ltd. All rights reserved.
Keywords: Phenoxide; Nickel; Platinum; Gold; Fluorinated aryloxide
1. Introduction
tones as in catecholase [3,4] or in aromatic hydroxyl-
ation as in tyrosinase [3,4]. Metal phenoxides, metal
alkoxides, and mixed-metal combinations of phenox-
ides and alkoxides are valuable precursors for metal
oxide ceramics [5]. Many important chelating ligands
in chemistry include phenolate units such as macrocy-
clic calixarenes [6] and salen systems [7]. Metal-based
homogeneous catalysts also make use of phenoxide li-
gands such as the alkyne metathesis catalysts prepared
by the Schrock group [8], hydrogenation systems from
the Rothwell group [9], and the zinc [10] and cad-
mium [11] compounds used in CO2/epoxide copoly-
merization developed by the D. Darensbourg group.
Late metal aryloxides had been less well studied than
Phenoxide and aryloxide ligands on transition me-
tal centers are highly important in many disparate
areas of science. In biology, metal–phenoxide linkages
are formed between a metal (most often a first-row
transition metal) and the phenolic side chain of tyro-
sine. Metal sequestration units often have multiple
phenoxide donor atoms for chelation such as transfer-
rin [1] or enterobactin [2]. Metal centers also bind to
phenoxide ligands during oxidation of phenols to ke-
*
Corresponding author. Tel.: +21 28 54 2 074; fax: +21 28 542 310.
E-mail address: ldoerrer@barnard.edu (L.H. Doerrer).
0277-5387/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2005.06.012

1804
M. Kim et al. / Polyhedron 24 (2005) 1803–1812
early transition metal derivatives [12], but more recent
work [13], including this paper, addresses the disparity
[14].
external 85% H3PO4. Microanalyses were performed
by H. Kolbe Microanalytisches Laboratorium, Mulheim
¨
an der Ruhr, BRD.
Phenoxides are anionic oxygen-donor ligands that of-
ten bridge metal centers and typically bind hard metal
centers in relatively high oxidation states. In transition
metal compounds requiring monodentate phenoxides,
one method to prevent bridging by the electron-rich
oxygen donors, is to furnish the ligand with bulky sub-
stituents at the 2- and 6-positions. Our laboratory has
demonstrated an alternative approach, namely that the
bridging propensity may be reduced by extensive fluori-
nation of the phenyl ring as in OC6F5 (OArF) or
OC6H3(CF3)2 (OAr0) [13]. This modification is an elec-
tronic approach, instead of a steric one, and thus results
in metal centers that may still bind to other ligands for
catalysis or more complex structure development. All
monodentate phenoxide ligands are simple X-type li-
gands in the MLXZ classification system [15], but their
steric and electronic properties differ significantly. Here-
in we describe four more compounds with monodentate
fluoroaryloxides whose simple OC6H5 analogs have not
been reported in all cases. These compounds serve to
develop further comparisons of OPh and OArF as
ligands as well as increase the number of known and
structurally characterized monodentate M–OArF and
M–OAr0 linkages.
2.2. Synthesis of [(Ph3P)2Ni(OArF)2] (1a)
In a 25 ml round bottom flask a portion of TlOArF
(0.3014 g, 0.7780 mmol) was dissolved in ꢀ10 ml
CH2Cl2. (PPh3)2NiCl2 (0.2529 g, 0.3866 mmol) was
added to the reaction mixture. The reaction mixture
turned a dark red-brown color and a white precipitate
also evolved. The reaction was left to stir overnight at
room temperature, and was filtered through Celite to re-
move TlCl. The mixture was concentrated in vacuo and
recrystallized from CH2Cl2 and hexanes (1:1). Dark
brown crystals were collected in 56% yield (0.2039 g).
1H NMR, (d, ppm, CD2Cl2) 6.780 (t, 6 H, para, J =
3
3
7.38 Hz), 7.347 (t, 12H, ortho, J = 7.83 Hz), 7.696 (t,
12H, meta, 3J = 7.38 Hz). 19F {1H} NMR, (d, ppm,
CD2Cl2) ꢁ153.99 (o, m), ꢁ171.04 (m, m), ꢁ177.47 (p,
m). UV–Vis (CH2Cl2) [kmax, nm (eM, cmꢁ1 Mꢁ1)] 456.0
(3698). Anal. Calc. for C48H30O2F10P2Ni: C, 60.73; H,
3.19. Found: C, 60.68; H, 3.21%.
2.3. Synthesis of [(PPh3)2Ni(OAr0)2] (1b)
In a 25 ml round bottom flask a portion of TlOAr0
(0.3003 g, 0.7744 mmol) was dissolved in ꢀ10 ml
CH2Cl2. (PPh3)2NiCl2 (0.2535 g, 0.3872 mmol) was
added to the reaction mixture. The reaction mixture
turned a dark red-brown color and a white precipitate
also evolved. The reaction was left to stir overnight at
room temperature, and was filtered through Celite to re-
move TlCl. The mixture was concentrated in vacuo and
recrystallized from CH2Cl2 and hexanes (1:1). Dark
brown crystals (0.3629 g) were collected in 90% yield.
1H NMR, (d, ppm, CD2Cl2) 6.350 (br, 2H, para-OAr0),
7.211 (br, 4H, ortho-OAr0), 7.260 (t, 12H, meta,
3J = 2.85 Hz), 7.680 (m, 18H, ortho + para). 19F {1H}
NMR, (d, ppm, CD2Cl2) ꢁ63.27 (CF3, s). UV–Vis
(CH2Cl2) [kmax, nm (eM, cmꢁ1 Mꢁ1)] 446.0 (2905), Anal.
Calc. for C52H36O2F12P2Ni: C, 59.97; H, 3.48. Found:
C, 59.77; H, 3.41%.
2. Experimental
2.1. General considerations
All studies were carried out at room temperature on a
Schlenk line or in a nitrogen- or argon-filled glovebox.
For solvents dried in stills, methylene chloride and deu-
terated methylene chloride were refluxed over CaH2.
THF and hexane were refluxed over potassium and tol-
uene was refluxed over sodium. All solvents were re-
fluxed under nitrogen or argon. Some work was also
done with solvents (hexanes, CH2Cl2, and toluene) dried
in a nitrogen-filled MBraun SPS (solvent purification
system) using Al2O3. Celite was dried overnight in vacuo
while heated to 125 °C with an oil bath. TlOC6F5
(TlOArF) and TlOC6H3(CF3)2 (TlOAr0) were prepared
according to our previously reported procedures [13].
[(Ph3P)Au(OPh)] was prepared from [(Ph3P)AuCl] and
KOPh [16]. All other reagents were obtained commer-
cially and were not purified further. NMR spectra were
measured on a Varian 300 MHz, Bruker 300 or
400 MHz spectrometer. UV–Vis data were recorded
2.4. Synthesis of [(COD)Pt(OArF)2] (2)
A portion of [(COD)2PtCl2] (151.5 mg, 0.4049 mmol)
was dissolved in 5 mL of CH2Cl2 and 2 equivalents of
KOArF (179.9 mg, 0.8098 mmol) in 5 mL of THF were
added. The solution immediately turned pale yellow
and a white precipitate (presumably KCl) was observed.
The solution was allowed to stir overnight and then the
precipitate was removed via filtration through Celite.
The solution was concentrated to dryness in vacuo,
and the crude very pale yellow product was recrystal-
lized from CH2Cl2 and hexanes. X-ray quality crystals
1
with a Varian Cary 50 spectrometer. H and 13C chem-
ical shifts were referenced to (CH3)4Si via the resonance
of residual protiosolvent (1H) or the 13C resonance of
the solvent. 19F shifts were referenced to external CFCl3.
31P shifts were referenced to internal (MeO)3PO4 or

M. Kim et al. / Polyhedron 24 (2005) 1803–1812
1805
1
were grown from the same mixture. Recrystallized yield
o-CF), 129.82 (d, m, CH, JCP = 12.1 Hz), 132.63 (d,
1
1
1
167 mg (61.6%). H NMR (d, ppm, CD2Cl2) 2.714 (q,
p, CH, JCP = 12.1 Hz), 134.72 (d, o, CH, JCP =
3
CH2, 4H, JHH = 8.0 Hz), 3.262 (m, CH2, 4H), 5.759
13.61 Hz). 19F {1H} NMR, (d, ppm, CD2Cl2) ꢁ164.65
(o, m,), ꢁ168.89 (m, m,), ꢁ180.10 (p, m). 31P (d, ppm,
CD2Cl2) 24.61. UV–Vis (CH2Cl2) [kmax, nm (eM,
cmꢁ1 Mꢁ1)] 236 (30,200), 268 (4460), 276 (3540). Anal.
Calc. for C24H15OF6PAu: C, 44.89; H, 2.35; F, 14.79.
Found: C, 44.97; H, 2.28; F, 14.67%.
3
(t, CH, 4H, JHH = 28.8 Hz). 13C {1H} NMR, (d,
1
ppm, CD2Cl2) 31.29 (s, CH2), 100.97 (t, CH, JCPt
=
76.7 Hz). 19F {1H} NMR, (d, ppm, CD2Cl2) ꢁ158.25
3
3
(o, d, JFF = 21.2 Hz), ꢁ164.55 (m, t, JFF = 21.5 Hz),
3
ꢁ158.25 (p, t of t, JFF = 15.2, 6.2 Hz). UV–Vis
(CH2Cl2) [kmax, nm (eM, cmꢁ1 Mꢁ1)] 233 (15200), 280
(8660). Anal. Calc. for C20H10O2F10Pt: C, 35.89; H,
1.81; F, 28.38. Found: C, 35.91; H, 1.79; F, 28.42%.
2.6. X-ray crystallography
A summary of crystal data, details of data collections
and refinement parameters for all compounds are given
in Table 1. X-ray diffraction data were collected using
2.5. Synthesis of [(Ph3P)Au(OArF)] (3)
˚
A portion of [(Ph3P)AuCl] (100.0 mg, 0.2021 mmol)
was dissolved in 5 mL of CH2Cl2. One equivalent of
KOArF (44.9 mg, 0.2021 mmol) was dissolved in 2 mL
of THF and the solutions mixed together. No obvious
color changes were observed. After stirring for several
hours, the solvents were removed in vacuo and the crude
product dissolved in 5 mL of CH2Cl2 and filtered
through Celite to remove presumed KCl. A saturated
solution of the product in CH2Cl2 (ꢀ1 mL) was pre-
pared and layered with an equal volume of hexanes to
yield colorless crystalline material, including crystals
suitable for X-ray diffraction. Recrystallized yield 60
Mo Ka radiation (k = 0.71073 A) on a Bruker SMART
APEX CCD (1a, 1b, 2) and a Siemens P4/CCD (3) dif-
fractometers [17]. Space groups were determined
through inspection of systematic absences (1a, 1b) and
intensity statistics (2, 3). All data were corrected for
absorption by SADABS [18] The structures were solved
using direct methods or the Patterson function and dif-
ference map techniques, and were refined by full-matrix
least squares procedures on F2. All non-hydrogen atoms
were refined with anisotropic displacement parameters.
The H atoms in 1a and 2 were found from the F-map
and refined with isotropic thermal parameters. In 1b
and 3 the H atoms were treated as idealized contribu-
tions. All software and sources of scattering factors
are contained in the SHELXTL program package [19].
1
mg (46.2%). H NMR (d, ppm, CD2Cl2) 7.53 (br, Ph).
13C {1H} NMR, (d, ppm, CD2Cl2) 120.14 (s, ipso-
OC6F5), 128.54 (s, m-CF), 128.99 (s, p-CF), 129.41 (s,
Table 1
Summary of X-ray crystallographic data
1a
1b
2
3
Formula
Formula weight
C48H30F10NiO2P2
949.37
C52H36F12 NiO2P2
1041.46
C20H12F10O2Pt
669.39
C24H15AuF5OP
642.30
ꢀ
ꢀ
Space group
P21/c
P21/n
P1
P1
˚
a (A)
11.4462(8)
15.5033(10)
11.1220(7)
10.5517(5)
14.8822(7)
29.7183(13)
7.4721(4)
10.2036(6)
13.1568(7)
71.170(1)
80.831(1)
82.371(1)
933.73(9)
2, 1
8.9435(7)
10.8180(8)
11.0364(9)
84.628(1)
81.113(1)
89.126(2)
1050.33(14)
2, 1
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
91.699(1)
92.829(1)
3
˚
V (A )
1972.8(2)
2, 0.5
4661.1(4)
4, 1
Z,Z0
Crystal color, habit
brown, plate
1.598
0.663
brown, block
1.484
0.574
colorless, block
2.381
7.629
colorless, block
2.031
7.138
qcalc (g cmꢁ3
)
l(Mo Ka) (mmꢁ1
)
Temperature (K)
100(2)
120(2)
100(2)
218(2)
Reflections measured
12614
29786
5919
7731
Reflections independent [Rint
Absorption correction
]
4675 [0.0492]
SADABS
10948 [0.0493]
SADABS
4110 [0.0156]
SADABS
4802 [0.0241]
SADABS
(Tmin/Tmax
)
(0.900)
0.0510
0.1204
(0.883)
0.0650
0.1579
(0.676)
0.0195
0.0483
(0.652)
0.0299
0.0730
R(F) (%)a
R(wF2) (%)b
P
P
a
R ¼ jjF oj ꢁ jF cjj= jF oj.
n
P
2
o
1=2
P
2
2
b
RðxF 2Þ ¼
½xðF 2o ꢁ F c2Þ ꢂ= ½xðF 2oÞ ꢂ
; x ¼ 1=½r2ðF o2Þ þ ðaPÞ þ bPꢂ; P ¼ ½2F c2 þ maxðF o; 0Þꢂ=3.

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M. Kim et al. / Polyhedron 24 (2005) 1803–1812
3. Results and discussion
ent strategies have been used to prevent polymerization
through bridging aryloxides or reduction of the metal
center. The most common approach is incorporation
of the aryloxide into a chelate ring (e.g., salen, salicylate,
quinolate) or a macrocycle (calixarene). Table 2 contains
the results of several searches in the Cambridge Struc-
tural Database V5.25 (CSD) [20] to put into context
the compounds discussed herein. These values represent
the crystallographically characterized subset of known
compounds and are therefore not an exhaustive survey
of all known compounds. They provide a quantitative
picture of the relative distribution of different types of
compounds in the literature.
The four compounds whose crystal structures are re-
ported herein are shown in Scheme 1. The compounds
add to the library of monodentate fluorinated aryloxide
compounds reported by our group [13] and others.
Extensive structural and spectroscopic studies of the
[Co(OArF)4]2ꢁ and [Cu(OArF)4]2ꢁ anions in comparison
with the well-known [CoCl4]2ꢁ and [CuCl4]2ꢁ anions
demonstrated that the pentafluorophenoxide ligand gen-
erates a similar but slightly stronger ligand field than
Clꢁ, consistent with qualitative expectations for the
more electronegative oxygen ligand. Attempts to make
[M(OPh)4]2ꢁ by analogous routes with perhydro OC6H5
led to exclusive formation of [(PhO)2M(l-OPh)2M-
(OPh)2]2ꢁ (M = Co, Cu) [13] anions with bridging
phenoxide ligands. These results suggested that highly
electronegative substituents on the aryloxide ring reduce
the electron density at the metal center and decrease
the bridging propensity of the aryloxide oxygen atom.
Described herein are further investigations of the late
transition metals with these highly fluorinated aryloxide
ligands and the effects of reduced electron density on
compound stability.
3.1.1. Nickel
Nickel aryloxide bonds are typically prepared with
chelating ligands, e.g., salen, as shown in Table 2, or
additional soft and somewhat p-accepting ligands in
the coordination sphere to balance the powerful dona-
tion from the aryloxide, with phosphines being the most
common. Interestingly, a survey [20] of structurally
characterized [(Ph3P)2NiX2] compounds (27 examples)
reveals no compounds with strongly Lewis basic Xꢁ
ligands (Fꢁ, CH3ꢁ) or oxygen donor atoms. Instead
softer ligands with p-acceptor character and/or sulfur
donor atoms are found with such electron rich ligands.
Nickel phosphine complexes with hard ligands have
more electron donating phosphines as in [(Me3P)2Ni-
(o-OC6H4-Cl)2] [21], [(Me3P)2Ni(OPh)(Me)] [22],
[(Et3P)2Ni(C5F4N)(OPh)] [23], [(Me3P)2NiMe(OArF)]
3.1. Synthesis
Successful synthesis of isolable metal–phenoxide
compounds results from control of the strongly nucleo-
philic character of the oxygen donor atom. Many differ-
F
F
CF3
F
F
F3C
F3C
F
O
Ni
O
P
P
O
P
Ni
O
CF3
F
P
F
F
1a
1b
F
F
F
F
F
F
F
F
O
Au
P
O
F
Pt
F F
O
F
F
F
F
F
2
Scheme 1.
3
F

M. Kim et al. / Polyhedron 24 (2005) 1803–1812
1807
Au
Table 2
Comparison of structurally characterizeda nickel, platinum, and gold aryloxide compounds
Category
Aryloxide linkage
Ni
Pt
A
B
C
D
E
F
G
H
a
M–OAr
850
14
325
56
752
21
63
76
9
4
38
29
5
14
5
17
7
0
10
9
3
A and acyclic OAr
M–(l2-OAr)–M0
P–M–OAr
(O,N)-M–OArb
A and D and E
A not D or E
G and acyclic OAr
1
0
3
Cambridge Structural Database V5.25 [20].
Includes five- and six-membered chelate rings.
b
Table 3
Selected interatomic distances, bond lengths and anglesa
˚
Compound
Distances (A)
Angles (°)
1a
Ni1–O1
Ni1–P1
O1–C1
P1–C7
P1–C13
P1–C19
1.852(2)
2.2862(7)
1.334(3)
1.827(3)
1.819(3)
1.822(3)
O1–Ni1–P1
O1–Ni1–P1_3
O1–Ni1–O1
P1–Ni1–P1
Ni1–O1–C1
Ni1–P1–C7
Ni1–P1–C13
Ni1–P1–C19
C7–P1–C13
C7–P1–C19
C13–P1–C19
88.88(7)
91.12(7)
180.00(8)
180.00(4)
126.71(19)
112.12(10)
112.13(10)
117.11(9)
105.09(12)
104.21(13)
105.14(13)
1b
Ni1–O1
Ni1–O2
Ni1–P1
Ni1–P2
O1–C1
O2–C9
P1–C17
P1–C23
P1–C29
P2–C35
P2–C41
P2–C47
1.858(3)
1.856(2)
2.2383(10)
2.2422(10)
1.281(5)
1.322(4)
1.814(4)
1.827(4)
1.817(4)
1.822(4)
1.815(4)
1.810(4)
O2–Ni1–O1
O1–Ni1–P1
O1–Ni1–P2
O2–Ni1–P1
O2–Ni1–P2
P1–Ni1–P2
Ni1–O1–C1
Ni1–O2–C9
Ni1–P1–C17
Ni1–P1–C23
Ni1–P1–C29
Ni1–P2–C35
Ni1–P2–C41
Ni1–P2–C47
178.49(12)
94.50(8)
86.32(8)
84.97(8)
93.94(9)
169.35(4)
122.4(2)
121.0(2)
111.91(12)
111.44(12)
118.04(12)
111.17(12)
117.50(13)
112.23(12)
2
Pt1–O1
Pt1–O2
Pt1–C1
Pt1–C2
Pt1–C5
Pt1–C6
C1–C2
C5–C6
O1–C9
O2–C15
2.014(2)
2.019(2)
2.153(3)
2.141(3)
2.146(3)
2.134(3)
1.409(5)
1.397(5)
1.328(4)
1.336(3)
Pt1–O1–C9
Pt1–O2–C15
O1–Pt1–O2
122.63(19)
122.59(19)
94.95(9)
3
Au1–O1
Au1–P1
O1–C1
P1–C11
P1–C21
P1–C31
2.028(3)
2.1978(11)
1.291(6)
1.796(4)
1.802(4)
1.803(4)
Au1–O1–C1
P1–Au1–O1
Au1–P1–C11
Au1–P1–C21
Au1–P1–C31
128.5(3)
172.76(9)
114.78(15)
112.96(14)
109.50(14)
a
Numbers in parentheses are estimated deviations of the last significant.

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M. Kim et al. / Polyhedron 24 (2005) 1803–1812
[24], [(Me3P)2Ni(OAr)2] [25], and trans-[(Bz3P)2NiH-
(OPh)] Æ HOPh [26]. More rarely nickel–aryloxide link-
ages are found with other strongly electron donating
ligands as observed in [(Cp*)(Et3P)Ni(p-OC6H4Me)]
[27] and [(py)3Ni(2,4,6-OC6Cl3H2)2] [28]. Nickel–arylox-
ide linkages have also been prepared with chelating O,P-
ligands that possess both hard and soft donor atoms
[29–31]. Usually the phenoxide is a monodentate ligand
but a few examples of bridging phenoxides have been
studied with allyl ligands such as [Ni(g3-allyl)-
(l2-OAr)]2 in diene polymerization [32–34] and bridging
phenoxide compounds have also been stabilized by the
multidentate Klaui ligand [35].
The present report addresses the effect of fluorination
in comparisons of OArF and OAr0 versus OPh and O-m-
C6H3(CH3)2 complexes. Toward that end only a handful
of nickel compounds with fluoroaryloxide ligands
have been reported previously including the anion
[36] [Ni2(C6F5)4(l2-OArF)2]2ꢁ and the neutral species
[Ni(g3-allyl)(l2-OArF)]2 and [Ni(g3-allyl)(l2-OAr0)]2
which were studied as diene polymerization activators
[32]. The polymeric [Ni(OArF)2]1 has also been reported
[37,38].
of 1b in CH2Cl2 showed only decay of the 1b absor-
bances and no new colored species (Supplementary
Figure 1).
Attempts to prepare the non-fluorinated analogs of
1a and 1b were unsuccessful. Reaction of [(Ph3P)2NiCl2]
with either KOPh or TlOPh in THF led to pale yellow
or yellow-orange solutions similar to the results of
decomposition of 1a. These results could indicate reduc-
tion of Ni to Ni(I) ([(Ph3P)3NiCl] is yellow, for example)
or Ni(0), but no clean products have been isolated.
Reaction of [(Ph3P)2NiCl2] with TlOPh in CH2Cl2 led
to insoluble orange powders. The insoluble orange
powders could be a reduced Ni species or a polymeric
Ni(II) compound formed by loss of phosphine. Two
equivalents of KO–m-C6H3(CH3)2 when reacted with
[(Ph3P)2NiCl2] produced copious amounts of an insolu-
ble brown/tan powder and yellow solution. These obser-
vations suggest that the formation of Ni–OAr bonds in
1a and 1b relies on the electron-withdrawing properties
of OArF and OAr0 to be stable on a [(Ph3P)2Ni]2+ cen-
ter. The formation of 1a and 1b, themselves somewhat
unstable in solution, is clearly made possible by the fluo-
rination of the aryloxide rings, in the absence of which,
soluble Ni(II) compounds are not obtained.
Simple reaction of [(Ph3P)2NiCl2] with the appropri-
ate TlOAr reagent yielded compounds 1a and 1b as
brown crystalline compounds. Under the same condi-
tions, reaction between [(Ph3P)2NiBr2] and TlOAr led
to insoluble materials. It has been previously reported
that [(Ph3P)2NiCl2] compounds are sensitive to reduc-
tion to Ni(I) with strong nucleophiles such as [NR2]ꢁ
and it may be that Ni(II) compounds with less electro-
negative halides are more susceptible to such reduction
under nucleophilic attack [39]. Too strongly basic li-
gands may lead to Ph3P dissociation and subsequent
decomposition or reduction of Ni(II) to Ni(I) or Ni(0).
A similar sensitivity for 1a and 1b to that previously ob-
served for [(Ph3P)2NiCl2] in CH2Cl2 [40–42] and CHCl3
[43] was noted. Attempts to synthesize these compounds
in THF, however, by methods analogous to those de-
scribed below for CH2Cl2 were unsuccessful and led to
colorless solutions with orange-brown precipitates.
[(Ph3P)2NiCl2] has been isolated in both tetrahedral
[44–47] (blue-green) and square-planar [46,48,49] (deep
red) forms but no evidence for a tetrahedral form of
1a or 1b has been observed. The square planar form
of [(Ph3P)2NiCl2] has been characterized only in the
presence of CH2Cl2 or ClCH2CH2Cl whereas crystals
of the tetrahedral isomer were prepared from neat etha-
nol. Some Ni(II) compounds exhibit a tetrahedral form
in non-coordinating solvents and an octahedral form in
donor solvents such as DMF [50] or DMSO [43] in
which solvent molecules are bound in two of six coordi-
nation sites. Compounds 1a and 1b are infinitely stable
in the solid state but the orange-brown CH2Cl2 or ace-
tone solutions turn pale-yellow over time, the latter
much more rapidly. A time-dependent UV–Vis study
3.1.2. Platinum
Reaction of [(COD)PtCl2] with two equivalents of
KOArF in THF cleanly afforded [(COD)Pt(OArF)2] with
no sign of Pt metal formation. (Use of thallium reagents
was avoided in the platinum and gold chemistry because
heterometallic M–Tl species sometimes have resulted in-
stead of thallium halide precipitation [51].) Platinum
bis(aryloxide) complexes of the form [L2Pt(OAr)2] are
relatively rare [52], with mono(aryloxides) [L2Pt(OAr)X]
being more common. Platinum(II) aryloxide com-
pounds summarized in Table 2 follow some of the same
trends as Ni(II) species, although there are far fewer of
the heavier congener because Pt(II) preferentially binds
heavier chalcogenides and this type of compound has
been studied more frequently. Consistent with this pref-
erence for softer ligands is the much greater fraction of
phosphine-bearing compounds for Pt versus Ni. Of the
14 Pt–OAr compounds that have neither a phosphine
nor a O,N chelate ring, only 5 do not have the phenoxide
involved in any chelate ring. There are two L2PtX2
cases, [(bpy)Pt(OPh)Me] [53] and [(g3-Me2N-C6H4-
CHCH2)Pt(OArF)Cl] [54] and one example each of
[L3PtX]+, [(terpy)Pt(3,4-OC6H3Me2)]BF4, [55] and [LPt-
X3]ꢁ, (Et4N)[Pt(C6F5)2(CO){p-OC6H4(NO2)}] [56], and
one Pt(IV) species, [(bpy)Pt(Me)2I(OPh)] [53].
Conspicuously absent are terminal platinum arylox-
ides with p-accepting ligands as demonstrated in 2. The
most similar known compound to 2 is the catecholate
derivative [(COD)Pt(O2C6H4)] [57]. No report existed
of [(COD)Pt(OPh)2] prior to our work and attempts to
make [(COD)Pt(OPh)2] by a route analogous to 2 led

M. Kim et al. / Polyhedron 24 (2005) 1803–1812
1809
to black-brown precipitates, suggestive of Pt reduction.
These observations suggest that an electron-withdrawing
aryloxide such as OArF is required to stabilize Pt–OAr
linkages in the absence of phosphines or chelates and
prevent ligand loss (COD) and subsequent metal reduc-
tion. Platinum compounds with OArF as a ligand are
also exceedingly rare [54,56,58,59].
3.1.3. Gold
Synthesis of [(Ph3P)Au(OArF)] (3) was achieved via
the straightforward metathesis of [(Ph3P)AuCl] with
KOArF at room temperature. No evidence of gold reduc-
tion was observed. Compounds with gold(I)–oxygen
bonds are relatively fewer in the literature compared to
gold(I)–phosphorous or gold(I)–sulfur because of the
relative hardness of oxygen ligands and the demon-
strated preference of gold for softer chalcogenide ligands
[60]. Only a few gold complexes with phenoxide ligands
have been reported in the literature [12,61], and the data
in Table 2 show only seven crystallographically charac-
terized species with acyclic Au–O–Ar linkages, six con-
taining Au(I) [62–66] and one with Au(III) [67]. Each
of these Au(I) examples has a tertiary phosphine trans
to the aryloxide ligand. The perhydro derivative
[(Ph3P)Au(OPh)] has been reported [16] but not charac-
terized with X-ray diffraction or UV–Vis spectroscopy.
Fig. 1. ORTEP diagram of [(Ph3P)2Ni(OArF)2] (1a). Hydrogen atoms
have been omitted for clarity. Selected distances (A) and angles (°):
Ni1–O1 1.852(2), Ni1–P1 2.2862(7), O1–C1 1.334(3); O1–Ni1–P1,
88.88(7), O1–Ni1–P1_3, 91.12(7), Ni1–O1–C1, 126.71(19). Ellipsoids
are shown at the 50% probability level.
˚
3.2. Structural characterization
There are only six crystallographically characterized
compounds [20] with [P2NiO2] coordination sphere.
Among these, five compounds have chelating ligands
and one is an octahedral compound with two bidentate
acetylacetonate-type ligands.
The nickel compounds [(Ph3P)2Ni(OArF)2] (1a) and
[(Ph3P)2Ni(OAr0)2] (1b) both contain square-planar
nickel centers with trans Ph3P ligands. Square planar
[(Ph3P)2NiX2] complexes are more rare than tetrahedral
isomers, but not unknown. The nickel atom in 1a,
shown in Fig. 1, sits on a center of inversion such that
one half of the molecule is in the asymmetric unit. Se-
lected distances and angles are listed in Table 3. The
Ni–PPh3 distance is well within the range of other
four-coordinate Ni(II)–PPh3 bond lengths. In a search
of the Cambridge structural database (CSD) V5.25
[20], 85 such compounds were found with an average
Fig. 2. ORTEP diagram of [(Ph3P)2Ni(OAr0)2] (1b). Hydrogen and
fluorine atoms have been omitted for clarity. Selected distances (A)
˚
and angles (°): Ni1–O1 1.858(3), Ni1–O2 1.856(2), Ni1–P1, 2.2383(10),
Ni1–P2, 2.2422(10), O1–C1, 1.281(5), O2–C9, 1.322(4); O2–Ni1–O1,
178.49(12), O1–Ni1–P1, 94.50(8), O1–Ni1–P2, 86.32(8), O2–Ni1–P1,
84.97(8), O2–Ni1–P2, 93.94(9), P1–Ni1–P2, 169.35(4), Ni1–O1–C1,
122.4(2), Ni1–O2–C9, 121.0(2). Ellipsoids are shown at the 50%
probability level.
˚
Ni–P bond length of 2.22(5) A. The angles around Ni
(Table 3) are virtually 90/180°. The only crystallograph-
ically characterized Ni–OArF species both have bridging
phenoxide ligands with necessarily longer average Ni–O
˚
rotation about the C–O bonds is expected. At this writ-
ing, except for 1b, crystallographically characterized
OAr0 linkages have been reported only in [M(OAr0)4]2ꢁ
compounds [13] and the [(Ar0O)2H]ꢁ anion [68]. Again
the distances and angles at the nickel center are within
the range of related complexes in the literature.
bond lengths of 1.933 [36] and 2.058(3) [35] A compared
to 1a.
The structure of 1b, shown in Fig. 2, is largely similar
to that of 1a. The most noticeable difference is that both
phenyl groups are on the same side of the NiO2P2 plane,
an artifact of crystal packing, whereas in solution free

1810
M. Kim et al. / Polyhedron 24 (2005) 1803–1812
Fig. 4. ORTEP diagram of [(Ph3P)Au(OArF)] (3). Hydrogen atoms
˚
have been omitted for clarity. Selected distances (A) and angles (°):
Au1–P1, 2.1978(11), Au1–O1 2.028(3), O1–C1 1.291(6); Au1–O1–C1
128.5(3), P1–Au1–O1, 172.76(9). Ellipsoids are shown at the 50%
probability level.
Fig. 3. ORTEP diagram of [(COD)Pt(OArF)2] (2). Hydrogen atoms
˚
have been omitted for clarity. Selected distances (A) and angles (°):
Pt1–O1 2.014(2), Pt1–O2 2.019(2), Pt1–C1 2.153(3), Pt1–C2 2.141(3),
Pt1–C5 2.146(3), Pt1–C6 2.134(3), C1–C2 1.409(5), C5–C6 1.397(5),
O1–C9 1.328(4), O2–C15 1.336(3); Pt1–O1–C9 122.63(19), Pt1–O2–
C15 122.59(19), O1–Pt1–O2 94.95(9). Ellipsoids are shown at the 50%
probability level.
Fig. 4 shows an ORTEP of compound 3 with a simple
LMX [15] motif. The geometry at Au is virtually linear,
as are the vast majority of Au(I) complexes [69,70]. The
˚
gold phenoxide bond is 2.028(3) A in length and the
Au–O–C angle is 128.5(3)°. The parameters are quite
similar to those of the five crystallographically charac-
terized Au(I) phenoxide compounds mentioned above
that have average Au–O distances of 2.03(1) A and
Au–O–C angles of 126(4)°. The intraligand distances
and angles are unexceptional.
The crystal structure of 2 is shown with an ORTEP in
Fig. 3, clearly demonstrating that this compound is a
member of the L2MX2 ligand class [15]. The cyclooct-
adiene ligand is bound in a g4-mode with the C@C
bonds perpendicular to the PtO2 plane. A plethora of
structurally characterized [(COD)Pt]2+ compounds ex-
ist, but relatively few with hard oxygen donor ligands,
consistent with the soft character of Pt(II) [69,70], and
only nine with a [(COD)Pt(O)2] coordination sphere,
according to a CSD search. The most relevant structural
comparison is that with [(COD)Pt(catecholate)] in which
the doubly-deprotonated catechol ligand forms a five-
membered chelate ring with platinum [57]. The Pt–O
˚
3.3. Spectroscopy
1
The H NMR chemical shifts in 1a and 1b are unex-
ceptional. Both phosphine and aryloxide ligands are ob-
served, though the signals decay over several hours.
When the solution colors have become pale or colorless,
1
only resonances for Ph3P are visible in the H and 31P
NMR spectra. No 31P NMR signals for coordinated
phosphine were observed, perhaps due to some para-
magnetic character of the decomposition products. In
the 19F NMR spectrum of 1a, three signals for the ortho,
meta, and para fluorine atoms are observed but the 3JFF
coupling is not resolved, in contrast to the spectrum of
compound 2 (vide infra). A singlet is observed for the
˚
bonds have lengths (A) of 1.972 and 1.978 in contrast
to the slightly longer average bond length in 2 of
2.017(2). The less basic OC6F5 ligand has been shown
previously to form slightly longer bonds [13]. The aver-
˚
age Pt–C bond lengths (A) are virtually the same in 2,
2.144(8), and the catecholate compound, 2.156(12).
Slightly shorter Pt–C bonds in 2 are consistent with less
donating fluorinated arlyoxide ligands that result in
more electron donation by the COD ligand. The coordi-
nated COD bonds in 2 have lengths consistent with dou-
1
CF3 groups in 1b. The H, 13C, and 19F NMR spectra
of 2 show bound COD and OArF ligands and are unex-
ceptional compared to other [(COD)PtX2] complexes
with oxygen-donor ligands in the literature [57,71].
The NMR spectra for 3 are consistent with the solid-
˚
ble bonds and within the range of 1.37(4) A in 205
crystallographically characterized [20] [(COD)Pt]2+
units. To our knowledge, only one prior report exists
of a crystallographically characterized Pt–OArF bond,
namely that in [(o-Me2NC6H4-CHCH2)Pt(OArF)Cl]
[54] which has Pt–O and O–C bond lengths of 2.017(5)
and 1.341(9) A, respectively. The former bond is virtu-
ally identical with that in 2 and the latter is somewhat
longer.
state structure shown in Fig.
unremarkable.
4 and otherwise
UV–Vis spectra for [(COD)PtCl2] and 2 are shown in
Supplementary Figure 2. Consistent with previous com-
parisons of Clꢁ versus OArFꢁ as ligands [13], the extinc-
tion coefficients increase significantly upon changing
halide to aryloxide, but the spectra are largely similar.
Increased absorbance above 300 nm is consistent with
˚

M. Kim et al. / Polyhedron 24 (2005) 1803–1812
1811
the pale yellow color of 2 versus the colorless starting
material. UV–Vis spectra for 3 are compared with
[(Ph3P)AuOPh] and [(Ph3P)AuCl] in Supplementary
Figure 3. Again the aryloxide derivatives absorb with
greater intensity than the halide, but no significant shifts
of the kmax values are observed, suggesting these transi-
tions do not involve exclusively the X ligand, but are lar-
gely p–p* transitions in the phosphine phenyl rings.
data_request/cif, or by emailing data_request@ccdc.
cam.ac.uk, or by contacting The Cambridge Crystallo-
graphic Data Centre, 12, Union Road, Cambridge
CB2 1EZ, UK; fax: +44 1223 336033. Supplementary
data associated with this article can be found, in the on-
line version, at doi:10.1016/j.poly.2005.06.012.
References
[1] Q.-Y. He, A.B. Mason, R.C. Woodworth, B.M. Tam, R.T.A.
MacGillivray, J.K. Grady, N.D. Chasteen, J. Biol. Chem. 273
(1998) 17018.
[2] K.N. Raymond, E.A. Dertz, S.S. Kim, Proc. Natl. Acad. Sci.
USA 100 (2003) 3584.
[3] E.A. Lewis, W.B. Tolman, Chem. Rev. 104 (2004) 1047.
[4] L.M. Mirica, X. Ottenwaelder, T.D.P. Stack, Chem. Rev. 104
(2004) 1013.
[5] D.C. Bradley, R.C. Mehrotra, I.P. Rothwell, A. Singh, Alkoxo
and Aryloxo Derivatives of Metals, 2nd ed., Academic Press, New
York, 2001, p. 704.
[6] D.M. Roundhill, Prog. Inorg. Chem. 43 (1995) 533.
[7] E.N. Jacobsen, Acc. Chem. Res. 33 (2000) 421.
[8] R.R. Schrock, Polyhedron 14 (1995) 3177.
[9] I.P. Rothwell, Chem. Commun. (1997) 1331.
[10] D.J. Darensbourg, M.W. Holtcamp, G.E. Struck, M.S. Zimmer,
S.A. Niezgoda, P. Rainey, J.B. Robertson, J.D. Draper, J.H.
Reibenspies, J. Am. Chem. Soc. 121 (1999) 107.
[11] D.J. Darensbourg, J.R. Wildeson, S.J. Lewis, J.C. Yarbrough, J.
Am. Chem. Soc. 124 (2002) 7075.
[12] D.C. Bradley, R.C. Mehrotra, I.P. Rothwell, A. Singh, in: Alkoxo
and Aryloxo Derivatives of Metals, 2nd ed., Academic Press, New
York, 2001, p. 704 (Chapter 6).
[13] M.C. Buzzeo, A.H. Iqbal, C.M. Long, D. Millar, S. Patel, M.A.
Pellow, S.A. Saddoughi, A.L. Smenton, J.F.C. Turner, J.D.
Wadhawan, R.G. Compton, J.A. Golen, A.L. Rheingold, L.H.
Doerrer, Inorg. Chem. (2004) 7709.
4. Summary
The late-transition metal complexes [(Ph3P)2Ni-
(OArF)2] (1a), [(Ph3P)2Ni(OAr0)2] (1b), and [(COD)Pt-
(OArF)2] (2) have been prepared and spectroscopically
as well as structurally characterized. The compound
[(Ph3P)Au(OArF)] (3) for which a preliminary synthetic
report exists, was also structurally and spectroscopically
characterized. These four compounds exemplify the con-
ditions under which electronic modification of aryloxide
ligands enables less common metal aryloxide bonds to
be formed. For late transition metals that prefer softer,
less donating ligands such as phosphorous or sulfur do-
nors, these monodentate aryloxide compounds are unu-
sual species. Among the four compounds, a perhydro
analog is known only for [(Ph3P)Au(OArF)]. Attempts
to make non-fluorinated analogs of the nickel and plat-
inum compounds resulted in metal precipitation, insolu-
ble products, or other evidence of metal reduction
instead of complex formation. The balance of electronic
effects from anionic X-type ligands and neutral L-type
ligands in this study suggests that highly basic aryloxides
promote ligand dissociation for weaker L donors, which
can lead to metal reduction and complex decomposition.
[14] J.R. Fulton, A.W. Holland, D.J. Fox, R.G. Bergman, Acc.
Chem. Res. 35 (2002) 44.
[15] M.L.H. Green, J. Organomet. Chem. 500 (1995) 127.
[16] S. Komiya, M. Iwata, T. Sone, A. Fukuoka, J. Chem. Soc.,
Chem. Commun. (1992) 1109.
[17] SMART: Software for the CCD Detector System, 5.626; Bruker
AXS: Madison, WI, 2000.
Acknowledgments
This work was supported by an NSF-CAREER
award (CHE-0134817) and the donors of the Petroleum
Research Fund administered by the American Chemical
Society (PRF #38007-GB3). The Barnard College NMR
facility is supported by the National Science Foundation
(DUE-9952633). L.H.D. thanks C.C. Cummins for hos-
pitality during a sabbatical when some of these data
were collected.
[18] G.M. Sheldrick, SADABS: Area Detector Absorption Correction,
University of Go¨ttingen, Go¨ttingen, BRD, 2001.
[19] G.M. Sheldrick, SHELXTL: Program Library for Structure Solution
and Molecular Graphics, 5.10, Bruker AXS, Madison, WI, 2000.
[20] F.H. Allen, Acta Crystallogr. B58 (2002) 380.
[21] H.-F. Klein, A. Dal, T. Jung, U. Flo¨rke, H.-J. Haupt, Eur. J.
Inorg. Chem. 44 (1998) 2027.
[22] Y.-J. Kim, K. Osakada, A. Takenaka, A. Yamamoto, J. Am.
Chem. Soc. 112 (1990) 1096.
[23] T. Braun, S. Parsons, R.N. Perutz, M. Voith, Organometallics 18
(1999) 1710.
[24] H.F. Klein, T. Wiemer, Inorg. Chim. Acta 189 (1991) 267.
[25] H.F. Klein, A. Dal, T. Jung, S. Braun, C. Roehr, U. Floerke,
H.J. Haupt, Eur. J. Inorg. Chem. (1998) 621.
Appendix A. Supplementary data
[26] A.L. Seligson, R.L. Cowan, W.C. Trogler, Inorg. Chem. 30
(1991) 3371.
[27] P.L. Holland, M.E. Smith, R.A. Andersen, R.G. Bergman, J.
Am. Chem. Soc. 119 (1997) 12815.
[28] M.F. Richardson, G. Wulfsberg, R. Marlow, S. Zaghonni, D.
McCorkle, K. Shadid, J. Gagliardi Jr., B. Farris, Inorg. Chem. 32
(1993) 1913.
Supplementary Figures 1–3 with UV–Vis spectra and
crystallographic information files for 1a, 1b, 2, and 3
have been deposited with the Cambridge Crystallo-
graphic Data Centre, CCDC Nos. 249765, 249766,
249767, and 249768, respectively. Crystallographic data
can be obtained free of charge via www.ccdc.cam.ac.uk/

1812
M. Kim et al. / Polyhedron 24 (2005) 1803–1812
[29] K.R. Dunbar, J.-S. Sun, A. Quillevere, Inorg. Chem. 33 (1994)
3598.
[30] J. Heinicke, A. Dal, H.-F. Klein, O. Hetche, U. Florke, H.-J.
Haupt, Z. Naturforsch. Teil B 54 (1999) 1235.
[31] J. Heinicke, M. Koehler, N. Peulecke, W. Keim, J. Catal. 225
(2004) 16.
[32] P.D. Hampton, S. Wu, T.M. Alam, J.P. Claverie, Organometallics
13 (1994) 2066.
[33] J. Campora, M.L. Reyes, T. Hackl, A. Monge, C. Ruiz,
Organometallics 19 (2000) 2950.
[52] J. Ni, C.P. Kubiak, Adv. Chem. Ser. 230 (1992) 515.
[53] G.M. Kapteijn, M.D. Meijer, D.M. Grove, N. Veldman, A.L.
Spek, G. van Koten, Inorg. Chim. Acta 264 (1997) 211.
[54] M.K. Cooper, N.J. Hair, D.W. Yaniuk, J. Organomet. Chem. 150
(1978) 157.
[55] X. Liu, S.L. Renard, C.A. Kilner, M.A. Halcrow, Inorg. Chem.
Commun. 6 (2003) 598.
[56] J. Ruiz, V. Rodriguez, G. Lopez, P.A. Chaloner, P.B. Hitchcock,
Organometallics 15 (1996) 1662.
[57] M.-J. Don, K. Yang, S.G. Bott, M.G. Richmond, J. Chem.
Crystallogr. 26 (1996) 335.
[58] W. Beck, B. Purucker, E. Strissel, Chem. Ber. 106 (1973) 1781.
[59] M.K. Cooper, D.W. Yaniuk, J. Organomet. Chem. 164 (1979)
211.
[34] J. Campora, M.L. Reyes, K. Mereiter, Organometallics 21 (2002)
1014.
[35] D.-q. Ma, S. Hikichi, M. Akita, Y. Moro-oka, Dalton (2000)
1123.
[36] G. Sanchez, F. Ruiz, J.L. Serrano, G. Garcia, G. Lopez, J.
Casabo, E. Molins, C. Miravitlles, Anal. Quim. 93 (1997) 49.
[37] R.S. Nyholm, B.R. Hollebone, J. Chem. Soc. A (1971) 332.
[38] S.T. Lin, R.N. Narske, K.J. Klabunde, Organometallics 4 (1985)
571.
[60] J.P.J. Fackler, W.E. vanZyl, B.A. Prihoda, Gold chalcogen
chemistry, in: H. Schmidbaur (Ed.), Gold: Progress in Chemistry,
Biochemistry and Technology, John Wiley & Sons, New York,
1999, p. 894.
[61] E.G. Perevalova, E.I. Smyslova, K.I. Granberg, Y.T. Struchkov,
L.G. Kuzꢀmina, D.N. Kravtsov, T.I. Voevodskaya, Koord. Khim.
15 (1989) 504.
[39] D.C. Bradley, M.B. Hursthouse, R.J. Smallwood, A.J. Welch, J.
Chem. Soc., Chem. Commun. (1972) 872.
[40] F.A. Cotton, O.D. Faut, D.M.L. Goodgame, J. Am. Chem. Soc.
83 (1961) 344.
[62] L.G. Kuzꢀmina, Y.T. Struchkov, Koord. Khim. 14 (1988)
1262.
[41] L.H. Pignolet, W.D. Horrocks Jr., R.H. Holm, J. Am. Chem.
Soc. 92 (1970) 1855.
[63] A. Kolb, P. Bissinger, H. Schmidbauer, Inorg. Chem. 32 (1993)
5132.
[42] L. Que Jr., L.H. Pignolet, Inorg. Chem. 12 (1973) 156.
[43] H. Kato, K. Yorita, Y. Kato, Bull. Chem. Soc. Jpn. 52 (1979)
2465.
[44] G. Garton, D.E. Henn, H.M. Powell, L.M. Venanzi, J. Chem.
Soc. (1963).
[45] H.J. Bruins Slot, W.K.L. Van Havere, J.H. Noordik, P.T.
Beurskens, P. Royo, J. Crystallogr. Spectrosc. Res. 14 (1984) 623.
[46] B. Corain, B. Longato, R. Angeletti, G. Valle, Inorg. Chim. Acta
104 (1985) 15.
[47] L. Brammer, E.D. Stevens, Acta Crystallogr. C C45 (1989) 400.
[48] J. Sletten, J.A. Kovacs, J. Crystallogr. Spectrosc. Res. 23 (1993)
239.
[64] L.G. Kuzꢀmina, O.Y. Burtseva, N.V. Dvortsova, M.A. Porai-
Koshits, E.I. Smyslova, Koord. Khim. 15 (1989) 773.
[65] L.G. Kuzꢀmina, Y.T. Struchkov, E.I. Smyslova, Koord. Khim. 15
(1989) 368.
[66] L.G. Kuzꢀmina, N.V. Dvortsova, M.A. Porai-Koshits, E.I.
Smyslova, K.I. Grandberg, Metalloorg. Khim. 2 (1989) 1179.
[67] T. Sone, M. Iwata, N. Kasuga, S. Komiya, Chem. Lett. (1991)
1949.
[68] M.C. Buzzeo, L.N. Zakharov, A.L. Rheingold, L.H. Doerrer, J.
Mol. Struct. 657 (2003) 19.
[69] A.F. Holleman, E. Wiberg, Inorganic Chemistry, Academic Press,
New York, 2001, p. 1884.
[49] A.S. Batsanov, J.A.K. Howard, Acta Crystallogr. E E57 (2001)
m308.
[50] H. Ohtsu, K. Tanaka, Inorg. Chem. 43 (2004) 3024.
[51] T. Devic, P. Batail, M. Fourmigue, N. Avarvari, Inorg. Chem. 43
(2004) 3136.
[70] F.A. Cotton, G. Wilkinson, C.A. Murillo, M. Bochmann,
Advanced Inorganic Chemistry, 6th ed., John Wiley & Sons
Inc., New York, 1999.
[71] A. Fukuoka, A. Sato, Ky. Kodama, M. Hirano, S. Komiya,
Inorg. Chim. Acta 294 (1999) 266.