Symmetrization of phenylmercuric hydroxides by the action of nickel(II) and cobalt(II) acetylacetonates. Isolation and structural characterization of an intermediate in this reaction

Article abstract of DOI:10.1021/om960799g

The complex adducts [M(acac)₂(PhHgOHgPh)]₂ (M = Co, Ni) have been obtained by incorporation of PhHgOH into the coordination sphere of M(acac)₂ at ambient temperature. The X-ray crystal structure of [Ni(acac)₂(PhHgOHgPh)(Et₂O)]₂ (1c) reveals a dimeric nickel complex coordinated by the acetylacetonate oxygen and the bridging oxygen of bis(phenylmercuric) oxide. Refluxing a THF solution of compound 1c gave diphenylmercury, HgO, and Ni(acac)₂(THF)₂. With PhHgOH or PhHgSH the symmetrization reactions also occurred when catalytic amounts of Ni(acac)₂ were used. In contrast, triphenyltin derivatives (hydroxide, acetate, oxide) on treatment with M(acac)₂ in aqueous THF gave the stable complexes [M(acac)₂(Ph₃SnOH)]₂ (M = Co, Ni). The structure of [Ni(acac)₂(Ph₃SnOH)]₂ (2) was also determined by X-ray crystallography.

Full text of DOI:10.1021/om960799g

Organometallics 1997, 16, 1879-1883
1879
Sym m etr iza tion of P h en ylm er cu r ic Hyd r oxid es by th e
Action of Nick el(II) a n d Coba lt(II) Acetyla ceton a tes.
Isola tion a n d Str u ctu r a l Ch a r a cter iza tion of a n
In ter m ed ia te in Th is Rea ction
Manfred Do¨ring* and Gabriela Hahn
Institut fu¨r Anorganische und Analytische Chemie, Universita¨t J ena,
A.-Bebel-Strasse 2, D-07743 J ena, Germany
Michael Stoll and Alexander C. Wolski
Institut fu¨r Anorganische Chemie I, Universita¨t Erlangen-Nu¨rnberg,
Egerlandstrasse 1, D-91058 Erlangen, Germany
Received September 18, 1996X
The complex adducts [M(acac)2(PhHgOHgPh)]2 (M ) Co, Ni) have been obtained by
incorporation of PhHgOH into the coordination sphere of M(acac)2 at ambient temperature.
The X-ray crystal structure of [Ni(acac)2(PhHgOHgPh)(Et2O)]2 (1c) reveals a dimeric nickel
complex coordinated by the acetylacetonate oxygen and the bridging oxygen of bis(phen-
ylmercuric) oxide. Refluxing a THF solution of compound 1c gave diphenylmercury, HgO,
and Ni(acac)2(THF)2. With PhHgOH or PhHgSH the symmetrization reactions also occurred
when catalytic amounts of Ni(acac)2 were used. In contrast, triphenyltin derivatives (hy-
droxide, acetate, oxide) on treatment with M(acac)2 in aqueous THF gave the stable complexes
[M(acac)2(Ph3SnOH)]2 (M ) Co, Ni). The structure of [Ni(acac)2(Ph3SnOH)]2 (2) was also
determined by X-ray crystallography.
Sch em e 1
In tr od u ction
Metal(II) acetylacetonates M(acac)2 (M ) cobalt,
nickel) form a series of adducts with alcohols, ethers,
and ketones.1 The ketone and ether adducts have
gained attention as intermediates in the cross-coupling
of Grignard reagents with acyl chlorides2 and silyl enol
ethers.3 Furthermore, these metal(II) acetylacetonates
have been used as catalysts in the formation of ethers
from alcohols and alkyl halides.4 The corresponding
alcohol and ether adducts should be intermediates of
that catalytic process. With regard to the catalytic ether
formation, we are examining the chemistry of organo-
mercuric and triorganotin hydroxides and oxides when
they have been incorporated into the coordination
sphere of nickel(II) and cobalt(II) acetylacetonates. Fur-
thermore, recent studies on the detoxification of orga-
nomercurials in enzymatic processes5 have stimulated
renewed interest in the coordination chemistry of or-
ganomercury compounds.6 Herein is reported the syn-
thesis of bis(phenylmercuric) oxide adducts [M(acac)2-
(PhHgOHgPh)]2 (1) starting from phenylmercuric hy-
droxide or the corresponding halides. Structural details
of the mercuric oxide bridged dimer [Ni(acac)2(PhHg-
OHgPh)(OEt2)]2 (1c) are given. Refluxing of 1 in tetra-
hydrofuran or toluene afforded a symmetrization of
PhHgOHgPh into Ph2Hg and HgO. With ArHgOH or
PhHgSH as the starting material, a catalytic variant
of this symmetrization is possible. These reactions rep-
resent a valuable catalytic version of the known sym-
metrization reactions of RHgX7 induced by stoichiomet-
ric amounts of Lewis bases such as phosphines8 and
amines.9 In this paper we also describe the synthesis
X Abstract published in Advance ACS Abstracts, April 1, 1997.
(1) (a) Siedle, A. R. in Comprehensive Coordination Chemistry;
Wilkinson, G., Gillard, R. D., McCleverty J . A., Eds.; Pergamon Press:
Oxford, U.K., 1987; Vol. 2, pp 365-412. (b) Pfluger, C. E.; Burke, T.
S.; Bednowitz, A. L. J . Cryst. Mol. Struct. 1973, 3, 181.
(2) (a) Naso, F. Pure Appl. Chem. 1988, 60, 79. (b) Fiandanese, V.;
Marchese, G.; Martina, V.; Ronzin, L. Tetrahedron Lett. 1984, 25, 4805.
(c) Cardellicchiso, C.; Fiandese, V.; Marchese, G.; Ronzini, L. Tetra-
hedron Lett. 1987, 28, 2053. (d) Do¨ring, M.; Uhlig, E. Dahlenburg, L.
Z. Anorg. Allg. Chem. 1989, 578, 58.
(3) Hayashi, T.; Katsuro, Y.; Okamoto, Y.; Kumada, M. Tetrahedron
Lett. 1980, 21, 3915.
(4) (a) Yamashita, M. Synthesis 1977, 803. (b) Camps, F; Coll, J .;
Moreto´, J . M. Synthesis 1982, 186.
(5) Moore, M. J .; Distefano, M. D.; Zydowsky, L. D.; Cummings, R.
J .; Walsh, C. T. Acc. Chem. Res. 1990, 23, 301.
(6) (a) Barbaro, P.; Cecconi, F.; Ghilardi, C. A.; Midollini, S.;
Orlandini, A.; Vacca, A. Inorg. Chem. 1994, 33, 6163. (b) Ghilardi, C.
A.; Midollini, S.; Orlandi, A.; Vacca, A. J . Organomet. Chem. 1994,
471, 29. (c) Cecconi, F.; Ghilardi, C. A.; Midollini, S.; Orlandini, A.;
Vacca, A. J . Organomet. Chem. 1996, 510, 153. (d) Cecconi, F.; Ghilardi,
C. A.; Innocenti, P.; Midollini, S.; Orlandini, A.; Ienco, A.; Vacca, A. J .
Chem. Soc., Dalton Trans. 1996, 2821.
(7) Wardell, J . L. in Comprehensive Organometallic Chemistry;
Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.; Pergamon Press:
Oxford, U.K., 1982; Vol. 2, p 892.
S0276-7333(96)00799-6 CCC: $14.00 © 1997 American Chemical Society

1880 Organometallics, Vol. 16, No. 9, 1997
Ta ble 1. Cr ysta llogr a p h ic Da ta for Com p lexes 1c a n d 2
Do¨ring et al.
1c
2
complex
formula
Mr
cryst syst
space group
T (K)
[Ni(acac)2(PhHgOHgPh)(Et2O)]2
[Ni(acac)2(Ph3SnOH)]2
C56H60O10Ni2Sn2
1247.84
triclinic
P1h
C52H68O12Ni2Hg4
1804.84
tetragonal
I41/acd
293
293
cryst size (mm)
a (Å)
b (Å)
0.3 × 0.25 × 0.5
18.953(2)
18.953(2)
33.173(4)
90
0.4 × 0.4 × 0.4
12.8551(3)
12.8667(2)
10.0971(6)
71.536(1)
73.684(1)
100.576(3)
1450.6(1)
1
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
90
90
11916.1(1)
8
Z
F(000)
D
6656
2.012
59.75
632
1.428
8.17
3.05-18.00
ω-2θ
5390
4060
3201
318
calc (g cm-3
)
µ(Ag KR) (cm-1
θ limit (deg)
scan mode
)
3.08-19.2
ω-2θ
no. of rflns measd
no. of indep rflns
no. of obsd rflns Fo > 2σ(Fo
no. of params
18458
2453
1639
154
2
2
)
GOF
R1
wR2
1.005
0.0300
0.0608
1.024
0.0348
0.0822
and molecular structure of the O(acac)-bridged dimer
[Ni(acac)2(Ph3SnOH)]2 (2), which was synthesized in the
course of this study.
Resu lts a n d Discu ssion
Syn th eses, Molecu la r Str u ctu r e, a n d Sym m etr i-
za tion Rea ction of Bis(p h en ylm er cu r ic) Oxid e Co-
or d in a ted to M(a ca c)2. The reaction of 2 equiv of
PhHgOH with M(acac)2 (M ) Co, Ni) at ambient temp-
erature afforded the hexametallic complexes [M(acac)2-
(PhHgOHgPh)]2 (1a , M ) Co; 1b, M ) Ni), respectively
(Scheme 1). Depending on the solvent used, adducts of
the type [M(acac)2(PhHgOHgPh)(solvent)]2 (solvent )
THF, diethyl ether, acetone, DMF) were obtained.
Furthermore, the complexes also were prepared in a
one-pot procedure in generally good (67%) yield by
hydrolysis of phenylmercuric chloride or acetate, re-
spectively, followed by treatment with M(acac)2. Two
principal points reflected the particular stability of the
complex compounds 1a and 1b: First, bis(phenylmer-
curic) oxide (PhHgOHgPh) was formed in the presence
of M(acac)2 at ambient temperature. In contrast, the
synthesis of PhHgOHgPh in the absence of complexing
agents required elevated temperature (100 °C) and
reduced pressure (0.3 Torr).10 Second, PhHgOHgPh is
capable of displacing strongly coordinated ligands such
as pyridine from their M(acac)2 complexes to form
adducts of the type 1. To elucidate the molecular
structure of the new paramagnetic phenylmercuric
oxide/M(acac)2 adducts, an X-ray structure determina-
tion of [Ni(acac)2(PhHgOHgPh)(Et2O)]2 (1c) was carried
out (Table 1). The single-crystal X-ray diffraction study
F igu r e 1. Molecular structure of complex 1c. Thermal
ellipsoids represent 30% probability contours.
established the hexametallic structure of a coordination
dimer; a drawing of 1c can be found in Figure 1.
Because of the crystallographic I 41/acd symmetry, with
two 2-fold axes through the Ni2O2 centroid and one
4-fold screw axis, only the bond distances and angles
in one-fourth of the molecule are listed in Table 2. Due
to this symmetry in 1c there is a planar Ni2O2 core
(internal angles ca. 82.0(3) and 98.0(3)°; Ni-Ni distance
3.16 Å). Surprisingly, the electron-deficient oxygen
atoms of PhHgOHgPh act as bridging atoms between
two cis-Ni(acac)2 fragments.
Generally, the bridging function in metal acetylac-
etonates requires an electron-rich oxygen atom. One
example for bridging by an oxygen atom of an additional
ligand is found in [Co(hfac)2(NITEt)]2 (hfac ) hexafluo-
roacetylacetonate, NITEt ) 4,4,5,5-pentamethyl-2-ethyl-
4,5-dihydro-1H-imidazolyl-1-oxy 3-oxide).11 In electron-
deficient O-donor ligands the bridging function is
(8) (a) Coates, G. E.; Lauder, A. J . Chem. Soc. 1965, 1857. (b)
Graddon, D. P.; Mondal, J . J . Organomet. Chem. 1976, 107, 1. (c)
Stanley, K.; Martin, J .; Schnitter, J .; Smith, R.; Baird, M. C. Inorg.
Chim. Acta 1978, 27, L111. (d) Reutov, O. A. Pure Appl. Chem. 1978,
50, 717.
(9) (a) J ensen, F. R.; Rickborn, B.; Miller, J . J . J . Am. Chem. Soc.
1966, 88, 340. (b) Seyferth, D.; Wade, R. C. J . Organomet. Chem. 1970,
22, 265.
(10) Bloodworth, A. J . J . Organomet. Chem. 1970, 23, 27.

Symmetrization of Phenylmercury Hydroxides
Organometallics, Vol. 16, No. 9, 1997 1881
Ta ble 2. Selected Bon d Dista n ces a n d An gles for
th e Com p lexes [Ni(a ca c)2(P h HgOHgP h )(Et2O)]2
(1c) a n d [Ni(a ca c)2(P h 3Sn OH)]2 (2)
length of the dative Hg-O bonds (3.16 Å) is very close
to the sum of the van der Waals radii,17 in contrast to
the doubly coordinated carbonyl compounds by biden-
tate Lewis acids derived from 1,2-phenylenedimercury
(2.68-2.77 Å).18 Consequently, the solvent molecules
are not strongly held at ambient temperature. The
solvent-free complexes 1b were obtained in pure form
from 1c in vacuo at 40 °C. The mercury(II) atoms in
1a or 1b exhibit a [2 + 3] coordination.19
To eliminate the coordinated PhHgOHgPh, THF and
toluene solutions of the complexes 1 were heated at re-
flux or sublimation of the complexes was attempted. In-
stead of the expected release of PhHgOHgPh, the major
products were diphenylmercury and mercuric oxide.
This reaction can be explained in terms of a metal-
assisted symmetrization of PhHgOHgPh (Scheme 1).
HgPh2 was isolated after flash chromatography in high
(85%) yield. Treatment of phenylmercuric hydroxide
with catalytic amounts of M(acac)2 in refluxing THF or
toluene also resulted in symmetrization to give HgPh2.
The catalytic symmetrization of phenylmercuric hydrox-
ide with M(acac)2 represents a far superior alternative
to the symmetrization of phenylmercuric halides with
stoichiometric amounts of phosphines8 or amines9 via
formation of stable HgX2 adducts according to eq 1.
1c
2
Bond Lengths (Å)
Ni(1)-O(1)
2.096(4) Ni(1)-O(11)
2.025(5) Ni(1)-O(11a)
2.010(5) Ni(1)-O(12)
2.041(3) Ni(1)-O(21)
2.042(8) Ni(1)-O(22)
3.228(6) Ni(1)-O(30)
2.730(5) O(22)-O(30a)
3.097(5) Sn(1)-O(30)
3.159(14) Sn(1)-C(31)
Sn(1)-C(41)
2.044(3)
2.109(3)
2.016(3)
1.988(3)
2.019(3)
2.062(3)
2.912(3)
1.983(3)
2.128(4)
2.121(5)
2.194(9)
Ni(1)-O(11)
Ni(1)-O(12)
Hg(1)-O(1)
Hg(1)-C(51)
Hg(1)-O(11)
Hg(1)-O(12a)
Hg(1)-O(12c)
Hg(1)-O(2)
Sn(1)-C(51)
Bond Angles (deg)
O(1)-Ni(1)-O(1a)
O(1)-Ni(1)-O(11)
82.1(3)
91.5(2)
O(11)-Ni(1)-O(11a) 80.1(1)
O(11a)-Ni(1)-O(21) 103.0(1)
O(12)-Ni(1)-O(21) 86.8(1)
O(21)-Ni(1)-O(22) 92.3(1)
O(11a)-Ni(1)-O(30) 83.6(1)
O(12)-Ni(1)-O(22) 97.1(1)
O(11)-Ni(1)-O(11a) 94.8(3)
O(11)-Ni(1)-O(12)
90.9(2)
O(11)-Ni(1)-O(12a) 88.5(2)
Ni(1)-O(1)-Ni(1a)
O(1)-Hg(1)-C(51)
97.9(3)
175.0(2) Ni(1)-O(11)-Ni(1a) 99.9(1)
Hg(1)-O(1)-Hg(1a) 119.4(3) Ni(1)-O(30)-Sn(1) 131.7(2)
O(1)-Hg(1)-O(2)
86.2(3)
C(31)-Sn(1)-O(30) 110.2(2)
C(51)-Sn(1)-O(30) 95.7(3)
C(41)-Sn(1)-O(30) 108.0(3)
O(1)-Hg(1)-O(12a) 73.7(2)
O(1)-Hg(1)-O(12c) 65.2(2)
O(1)-Hg(1)-O(11)
C(51)-Hg(1)-O11)
63.6(3)
112.7(2)
2PhHgX + nL f HgPh2 + HgX2Ln
L ) phosphines (n ) 2), ammonia,
(1)
C(51)-Hg(1)-O(12a) 101.5(2)
C(51)-Hg(1)-O(12c) 114.5(3)
undertaken by the more electron-rich atoms of the acac
ligands, e.g., in the dimeric complexes [Co(acac)2(H2O)]2
and [Ni(acac)2(piperidine)]2.12 The bridging mode in 1c
is favored by an extension of the coordination number
on mercury, a common phenomenon in the inorganic
chemistry of mercury(II) compounds.13 Using the maxi-
mum sum of van der Waals radii of oxygen (1.50 Å) and
mercury (1.73 Å) for a bonding interaction14 between
oxygen and mercury, other weak intramolecular Hg-
O(acac) interactions exist in 1c with long Hg-O dis-
tances (Hg(1)-O(12a) ) 2.730(5) Å, Hg(1)-O(12c) )
3.097(5) Å, Hg(1)-O(11) ) 3.228(6) Å). With the
additional secondary bonding between mercury and the
oxygen atom of the ether, the mercury(II) atom has a
effective coordination number of 5 or 6, resulting in a
strongly distorted pentagonal or octahedral geometry
around mercury(II). Similar complexes having second-
ary bonding interactions have been reported, e.g., 3.08-
(2) Å for the Hg-O distance of [Hg(SC5H9NH(CH3))2]-
amines (n ) 2), 2,2′-bipyridine,
bidentate phosphines (n ) 1)7-9
Similar chemistry was observed with other arylmer-
curic hydroxides such as p-CH3O-C6H4HgOH and p-CH3-
C6H4HgOH or the Schiff base p-Ph-CH)NC6H4HgOH
prepared from the corresponding halides or acetates as
shown in eq 2. The catalytic symmetrization provided
the diarylmercury compound.
R
HgO2CCH3
+NaOH,
–NaO2CCH3
CHPh
(A): R = H, N
cat.
Ni(acac)2
R
HgOH
R
Hg
R + HgO + H2O
+NaOH,
–NaCl
(B): R = H, CH3, OCH3
(2)
15
[ClO4]2 and 2.722(6), 2.826(6), and 3.189(6) Å for
bis[2,6-bis(pivaloylamino)benzenethiolato]mercury.16
R
HgCl
The ether oxygen atoms in 1c interact simultaneously
and symmetrically with both mercury atoms, but the
Phenylmercuric mercaptan (PhHgSH) also was sym-
metrized in the presence of a catalytic amount of Ni-
(acac)2 according to eq 3. In this case, the reaction
already proceeded at room temperature and an inter-
(11) Caneschi, A.; Gatteschi, D.; Laugier, J .; Rey, P.; Sessoli, R.
Inorg. Chem. 1988, 27, 1553.
(12) (a) Cotton, F. A.; Elder, R. C. Inorg. Chem. 1966, 5, 423. (b)
Hursthouse, B.; Laffey, M. A.; Moore, P. T.; New, D. B.; Raithby, P.;
Thornton, P. J . Chem. Soc., Dalton Trans. 1982, 307.
(13) (a) Grdenic, D. Q. Rev. Chem. Soc. 1965, 19, 303. (b) Dean, P.
A. W. Prog. Inorg. Chem. 1978, 24, 109. (c) Do¨ring, M.; Go¨rls, H.; Uhlig,
E.; Brodersen, K.; Dahlenburg, L.; Wolski, A. Z. Anorg. Allg. Chem.
1992, 614, 65.
(14) (a) Wright, J . G.; Natan, M. J .; MacDonnell, F. M.; Ralston, D.
M.; O’Halloran, T. V. In Progress in Inorganic Chemistry; Lippard, S.
J ., Ed.; Wiley: New York, 1990; Vol. 38, pp 332-434. (b) Canty, A J .;
Deacon, G. B. Inorg. Chim. Acta 1980, 45, L225.
(17) An analogous structure has been obtained with THF ligands
instead of ether and Co(II) instead of Ni(II). [Co(acac)2(PhHgOHgPh)-
(THF)]2 (C44H44O10Co2Hg4): Mr ) 1801.26, monoclinic, P21/c, a
)
10.466(1) Å, b ) 22.390(2) Å, c ) 12.715(1) Å, â ) 103.623(6)°, V )
2895.6(4) Å3, Z ) 2, Dcalc ) 2.066 gcm-3, λ(Ag KR) ) 0.560 142 Å, µ )
61.03 cm-1, T ) 293 K, R1 ) 0.0358 for 2549 unique observed
2
reflections with Fo > 2σ(Fo2) and 323 parameters. Stoll, M.; Wolski,
A. C.; Do¨ring, M. Unpublished results.
(18) (a) Vaugeois, J .; Simard, M.; Wuest, J . D. Coord. Chem. Rev.
1995, 145, 55. (b) Simard, M.; Vaugeois, J .; Wuest, J . D. J . Am. Chem.
Soc. 1993, 115, 370. (c) Beauchchamp, A. L.; Olivier, M. J .; Wuest, J .
D.; Zacharie, B. Organometallics 1987, 6, 1533.
(15) Barrera, H.; Bayon, J . C.; Gonza´lez-Duarte, P.; Sola, J .; Vin˜as,
J . M. Polyhedron 1982, 1, 647.
(16) Ueyama, N.; Taniuchi, K.; Okamura, T.; Nakamura, A.; Maeda,
H.; Emura, S. Inorg. Chem. 1996, 35, 1945.
(19) Stoll, M. Ph.D. Thesis, Erlangen, Germany, 1993.

1882 Organometallics, Vol. 16, No. 9, 1997
Do¨ring et al.
or the complex [Co(acac)2(H2O)]2.12 Two intramolecular
hydrogen bonds (2.912 Å) in 2 exist between the
hydrogen of the hydroxide of R3SnOH and one oxygen
atom of the nonbridging acetylacetonate ligand. The
coordinated Ph3SnOH in 2 has a distorted tetragonal
environment with short Sn-O-bonds (1.98 Å). In
contrast, uncoordinated triphenyltin hydroxide crystal-
lizes in a polymeric chain with a five-coordinate [C3O2]
core.22 Thus, the Sn-O bonds in the latter compound
are expanded (2.20 and 2.25 Å).
Con clu sion s
Novel M(acac)2 adducts containing PhHgOHgPh and
Ph3SnOH ligands have been prepared. Compound 1 is
an intermediate in the catalytic symmetrization of
PhHgOH by M(acac)2. PhHgOHgPh is formed in a
metal(II) coordination sphere and is activated to un-
dergo the symmetrization reaction, in which HgPh2 and
HgO are formed. We are continuing our studies of the
utility of coordination compounds in the stabilization
intermediates of organometallic reactions.
F igu r e 2. Molecular structure of complex 2. Thermal
ellipsoids correspond to 30% probability.
Exp er im en ta l Section
Ma ter ia ls a n d P r oced u r es. Ni(acac)2, Co(acac)2, and the
pyridine adduct Ni(acac)2(py)2 were prepared as described in
the literature.23 Arylmercuric hydroxides were synthesized
either from the arylmercuric halides24 or the acetates10 ac-
cording to the literature procedures.25 All other reagents were
obtained commercially and used as supplied. All experiments
were carried out under argon by standard Schlenk techniques.
Solvents were purified by standard methods. IR spectra
(4000-450 cm-1) were recorded on a Perkin-Elmer 2000 FT-
IR spectrometer in Nujol mulls between KBr disks. NMR
spectra were recorded at room temperature on a Bruker AC
200F spectrometer (1H, 200 MHz; 13C, 50 MHz). Elemental
analyses were carried out on a Carlo-Erba 1106 Elemental
Analyser (Erlangen, Germany) or on a Leco CHNS-932 El-
emental Analyser (J ena, Germany).
mediate bis(phenylmercuric) sulfide or a complex, analo-
gous to 1, was not isolable.
cat. Ni(acac)2
(3)
+ HgS + H2S
HgSH
Hg
2
(C)
Syn th eses a n d Molecu la r Str u ctu r e of th e Tr i-
p h en yltin Hyd r oxid e Ad d u ct of Ni(a ca c)2. When
triphenyltin hydroxide was used instead of PhHgOH,
formation of a comparable bis(triphenyltin) oxide com-
plex was not observed. In contrast, a dimeric adduct of
type [Ni(acac)2(Ph3SnOH)]2 2 was obtained. This com-
plex also was formed by hydrolysis of triphenyltin
acetate and bis(triphenyltin) oxide in the presence of a
stoichiometric amount of Ni(acac)2 according to eqs 4
and 5.
P r ep a r a tion of [Ni(a ca c)2(P h HgOHgP h )(Et2O)]2 (1c)
fr om P h HgOH. PhHgOH (2.3 g, 7.8 mmol) was added to a
solution of Ni(acac)2 (1.0 g, 3.9 mmol) or Ni(acac)2(py)2 (1.6 g,
3.9 mmol) in 20 mL of THF. After an ultrasonic treatment
for 30 min at room temperature, the solvent was evaporated
in vacuo. The residue was extracted with 30 mL of ether, and
the extract was filtered through a bed of Celite. The filtrate
was concentrated to approximately 10 mL. Cooling to -20 °C
afforded green crystals overnight, which were isolated by
decanting and washed with several portions of cold ether.
Yield: 2.7 g, 78%. Anal. Calcd for C52H68O12Ni2Hg4: C, 34.96;
Ph3SnOSnPh3 + 2Ni(acac)2 + H2O f
[Ni(acac)2(Ph3SnOH)]2 (4)
2Ph3SnO2CCH3 + 2Ni(acac)2 + 2H2O f
[Ni(acac)2(Ph3SnOH)]2 + 2CH3CO2H (5)
H, 3.81. Found: C, 34.09; H, 3.62. IR (cm-1): 3068, 3061 (νCH
,
Suitable crystals for X-ray diffraction studies of 2
were grown by slowly diffusing hexane into a THF
solution of the complex. An ORTEP representation of
the observed structure is shown in Figure 2. Due to
the crystallographic center of symmetry, only the bond
distances and angles in half of the molecule are listed
in Table 2. As can be seen, the tetrametallic compound
is formed by two fragments, Ni(acac)2(Ph3SnOH), as
expected, with bridging by the oxygen atoms of the
acetylacetonate. The bridging plane is oriented parallel
and is coplanar with the Ni2O2 bridging plane. Accord-
ingly, the complex should exhibit antiferromagnetic
coupling (Ni-Ni ) 3.18 Å)20 in the same manner as the
Ph), 1584 (νCdO), 1516 (δCH , acac), 728, 699 (δCH, Ph), 670
(νas,Hg-O-Hg).
3
P r ep a r a tion of [Ni(a ca c)2(P h HgOHgP h )(Et2O)]2 (1c)
fr om P h HgCl. To a solution of PhHgCl (1.5 g, 4.8 mmol) in
50 mL of THF was added NaOH (0.19 g, 4.8 mmol) and 5 mL
of water. The resulting mixture was heated at reflux for 1 h.
After filtration through a bed of Celite, Ni(acac)2 (0.62 g, 2.4
mmol) was added and the solution was treated by ultrasound
for 30 min. Workup identical with that above gave 1c as green
crystals. Yield: 1.45 g, 67%. Anal. Found: C, 34.48; H, 3.70.
P r ep a r a tion of [Ni(a ca c)2(P h HgOHgP h )]2 (1b). Heat-
ing compound 1c in vacuo at 50 °C resulted in loss of Et2O
(22) Glidewell, C.; Lilies, D. C. Acta Crystallogr. 1978, B34, 129.
(23) Heyn, B.; Hipler, B.; Kreisel, G.; Schreer, H.; Walther, D.
Anorganische Synthesechemie; Springer: Berlin, 1986; pp 120-123.
(24) Koten, I. A.; Adams, R. J . Am. Chem. Soc. 1924, 46, 2764.
(25) Details of arylmercuric hydroxide characterization are given
in the supporting information.
21
isostructural isopropanol adduct [Ni(acac)2(i-C3H7OH)]2
(20) Butcher, R. J .; O’Connor, C. J .; Sinn, E. Inorg. Chem. 1981,
20, 3486.
(21) O’Connor, C. J .; Stevens, E. D. Inorg. Chim. Acta 1984, 81, 91.

Symmetrization of Phenylmercury Hydroxides
Organometallics, Vol. 16, No. 9, 1997 1883
and gave a green, microcrystalline product: Anal. Calcd for
Hg(p-C6H4NdCHP h )2. Following the procedure B with
p-PhHCdN-C6H4HgO2CCH3 (2.5 g, 5.7 mmol), synthesized by
heating of 2.0 g (5.7 mmol) of p-H2N-C6H4HgO2CCH3 and 0.58
mL (5.7 mmol) of benzaldehyde in refluxing methanol in
quantitative yield, 0.23 g (5.7 mmol) of NaOH, and Ni(acac)2
(0.05 g) gave 0.45 g (28%) of Hg(p-C6H4N)CHPh)2. Mp: 181
°C (lit.30 Mp 180 °C). Anal. Calcd for C26H20N2Hg: C, 55.66;
H, 3.59; N, 4.99. Found: C, 55.61; H, 3.56; N, 4.95. 1H NMR
(CDCl3): δ 8.46 (s, 1H, CH), 7.24-7.93 (m, 9H, aryl). 13C NMR
(CDCl3): δ 168.22 (C-Hg), 160.34 (CHdN), 151.95 (C-N),
138.07, 136.34, 131.35, 128.85, 128.76, 121.01 (aryl). IR (cm-1):
1621 (νCdN), 1570, 1447 (νCdC), 819, 755, 717, 692 (δCH, aryl).
[Ni(a ca c)2(P h 3Sn OH)]2 (2). To a solution of Ni(acac)2 (1.0
g, 3.9 mmol) in 50 mL of THF was added 3.9 mmol of the
appropriate organotin compound Ph3SnOR′ (a, R′ ) H; b, R′
) CH3CO, c, R′ ) SnPh3). In addition, using b or c 3.9 mmol
of water was added. After an ultrasonic treatment for 30 min
at room temperature the reaction mixture was filtered through
Celite. The filtrate was concentrated to approximately 20 mL,
and 10 mL of n-hexane was added. Cooling to -20 °C
overnight afforded green crystals. Yield: 1.7 g, 70%. Anal.
Calcd for C56H60O10Ni2Sn2: C, 53.90; H, 4.85. Found: C, 53.85;
H, 4.89. IR (cm-1): 3339 (νOH), 3065, 3048 (νCH, Ph), 1595
C
44H48O10Ni2Hg4: C, 31.90; H, 2.92. Found: C, 31.76; H, 2.82.
P r ep a r a tion of [Co(a ca c)2(P h HgOHgP h )]2 (1a ). With
2.3 g of PhHgOH and 1.0 g of Co(acac)2 as starting materials,
the same procedure provided 2.0 g (63% yield) of pink micro-
crystals. Anal. Calcd for C44H48O10Co2Hg4: C, 31.90; H, 2.92.
Found: C, 31.83; H, 2.83.
Syn th esis of HgP h 2 via 1c. Compound 1c, 0.5 g (0.28
mmol), was sublimed at 200 °C and atmospheric pressure to
yield 0.17 g (85%) of HgPh2. Mp: 121 °C (lit.26 mp 121-122
°C). Anal. Calcd for C12H10Hg: C, 40.61; H, 2.82. Found: C,
40.58; H, 2.79. 13C NMR (CDCl3, 25 °C): δ 170.44 (C-Hg),
137.55, 128.63, 128.27 (aryl).27 IR (cm-1): 1574 (νCdC), 736, 732,
696 (δCH, Ph).
Ca ta lytic Sym m etr iza tion of HgP h 2. P r oced u r e A. A
mixture of PhHgCl (6.3 g, 20 mmol) in toluene (50 mL) and
NaOH (0.8 g, 20 mmol) in water (20 mL) was heated at reflux
for 30 min. After separation of the aqueous phase, Ni(acac)2
(0.1 g, 0.4 mmol) was added and the mixture was again heated
in refluxing toluene. After 3 h, a yellow solution was obtained.
Flash chromatography (silica, 2:1 toluene/acetone) provided
2.4 g (66%) of HgPh2. Anal. Found: C, 40.57; H, 2.81.
P r oced u r e B. A mixture of PhHgO2CCH3 (3.0 g, 9.0 mmol)
in toluene (40 mL) and NaOH (0.36 g, 9.0 mmol) in water (10
mL) was heated at reflux for 1 h. The preceding reaction and
workup identical with that as described in procedure A gave
1.1 g (70%) of HgPh2. Anal. Found: C, 40.55; H, 2.78.
P r oced u r e C. A solution of PhHgSH24 (1.8 g, 5.8 mmol)
and 0.05 g of Ni(acac) was stirred in 30 mL of toluene at
ambient temperature. After 2 days HgS had precipitated
quantitatively. The mixture was filtered, and the filtrate was
concentrated in vacuo to provide 0.8 g (83%) of HgPh2. Anal.
Found: C, 40.60; H, 2.82.
(νCdO), 1518 (δCH , acac), 731, 698 (δCH, Ph).
3
X-Ra y Str u ctu r e Deter m in a tion s. X-ray diffraction data
were collected on a Phillips PW1100 four-cycle automatic
diffractometer with graphite-monochromated Ag KR radiation
(λ ) 0.560 142 Å). The crystals were embedded in a drop of
fast-hardening adhesive (1c) or sealed inside a glass capillary
(2). The structures were solved by direct methods (SHELXS-
86)31 and refined by full-matrix least-squares techniques
against F2 (SHELXL-93).32 An absorption correction for
compound 1c was based on ψ-scan solution. Hydrogen atom
contributions were calculated but not refined. In the final
cycles all non-hydrogen atoms, except the solvent in 1c, were
refined anisotropically. The carbon atom positions of the third
phenyl group in compound 2 had to be split because of disorder.
The program XP (Siemens Analytical X-ray Instruments, Inc.)
was used for structure representation.
(p-CH3O-C6H4)2Hg. Following the procedure A described
above for HgPh2 with p-CH3O-C6H4HgCl (2.0 g, 5.8 mmol),
NaOH (0.23 g, 5.8 mmol), and 0.05 g of Ni(acac)2 gave (p-CH3O-
C6H4)2Hg (0.95 g, 79%). Mp: 204 °C (lit.28 mp 202 °C). Anal.
Calcd for C14H14O2Hg: C, 40.53; H, 3.40. Found: C, 40.43;
H, 3.46. 1H NMR (CDCl3): δ 7.36 (d, 2H, J ) 8.4 Hz,
m-CH),7.01 (d, 2H, J ) 8.4 Hz, o-CH), 3.81 (s, 3H, OCH3). 13
C
NMR (CDCl3, 25 °C): δ 162.34 (C-Hg), 159.55 (C-OCH3),
138.28, 114.31 (aryl), 55.05 (OCH3). IR (cm-1): 1586, 1564
(νCdC), 817, 808, 789 (δCH, aryl).
Ack n ow led gm en t. We thank the Deutsche Fors-
chungsgemeinschaft and Fonds der Chemischen Indus-
trie for financial support.
(p-CH3-C6H4)2Hg. Following the procedure A with p-CH3-
C6H4HgCl (1.9 g, 5.7 mmol), NaOH (0.23 g, 5.7 mmol), and
Ni(acac)2 (0.05 g) gave (p-CH3-C6H4)2Hg (0.92 g, 83%). Mp:
246 °C (lit.29 Mp 244 °C). Anal. Calcd for C14H14Hg: C, 43.92;
H, 3.69. Found: C, 43.72; H, 3.76. 1H NMR (CDCl3): δ 7.44
(d, 2H, J ) 7.4 Hz, m-CH), 7.17 (d, 2H, J ) 7.4 Hz, o-CH),
2.30 (s, 3H, CH3). 13C NMR (CDCl3, 25 °C): δ 167.20 (C-
Hg), 138.18, 136.94, 129.54 (aryl), 20.98 (CH3). IR (cm-1):
1592, 1493 (νCdC), 792 (δCH, aryl).
Su p p or tin g In for m a tion Ava ila ble: Details of the struc-
ture determinations, including tables of atomic coordinates,
bond distances and angles, and thermal parameters for 1c and
2, and characterization data for arylmeruric hydroxides (17
pages). Ordering information is given on any current mast-
head page.
OM960799G
(26) Fields, R.; Haszeldine, R. N. J . Chem. Soc. C 1967, 2559.
(27) Petrosyan, V. S.; Reutov, O. A. J . Organomet. Chem. 1974, 76,
123.
(28) Michaelis, A.; Ratinerson, J . Chem. Ber. 1890, 23, 2344.
(29) Nesmejanow, A. N.; Kahn, E. J . Chem. Ber. 1929, 62, 1019.
(30) Vorla¨nder, R. Z. Phys. Chem. 1923, 105, 230.
(31) Sheldrick, G. M. SHELXS-86: A Program for Crystal Structure
Solution; University of Go¨ttingen, Go¨ttingen, Germany, 1986.
(32) Sheldrick, G. M. SHELXL-93: A Program for Crystal Structure
Refinement; University of Go¨ttingen, Go¨ttingen, Germany, 1993.