2498
Organometallics 1997, 16, 2498-2499
Syn th esis, Rea ctivity, a n d Ch a r a cter iza tion of
Ru th en ocen es Bea r in g P en ta zin ca ted Cyclop en ta d ien yl
Liga n d s
Kapila N. Seneviratne and Charles H. Winter*
Department of Chemistry, Wayne State University, Detroit, Michigan 48202
Received February 19, 1997X
Sch em e 1. P r ep a r a tion a n d Rea ction s of 2
Summary: Treatment of pentakis(chloromercurio)pen-
tamethylruthenocene or decakis(chloromercurio)rutheno-
cene with dimethylzinc affords ruthenocenes containing
pentazincated cyclopentadienyl ligands. The reactivity
of the perzincated ruthenocenes is presented, along with
insight into the structures of these species.
Aromatic compounds in which all of the hydrogens
on the aromatic ring have been replaced by metal
substituents represent an extremely rare class of
molecules.1-5 Recently, we reported the preparation
and characterization of perlithiated ruthenocenes2 and
permagnesiated ruthenocenes.3 However, treatment of
the perlithiated and permagnesiated ruthenocenes with
most electrophiles afforded hydrogen-substituted ru-
thenocene derivatives by abstraction of hydrogen from
the solvent.4 Accordingly, we sought to examine the
preparation of other permetalated ruthenocenes that
might exhibit more useful reactivity. Organozinc com-
pounds are well-known to be less reactive than analo-
gous organolithium or organomagnesium compounds,6
and zinc-substituted ruthenocenes might be less prone
to abstract hydrogen atoms from solvents. Herein, we
report the synthesis and reactivity of two ruthenocene
derivatives bearing pentazincated cyclopentadienyl
ligands and offer insight into the solid state and solution
structures of these species. To the best of our knowl-
edge, these are the first perzincated aromatic com-
pounds. Furthermore, the perzincated ruthenocenes
react with several moderate electrophiles to afford
persubstituted derivatives and, thus, represent a prom-
ising new class of synthetic intermediates.
Treatment of pentakis(chloromercurio)pentamethyl-
ruthenocene3 (1) with dimethylzinc (ca. 12 equiv) in
toluene at 23 °C for 2 h led to the formation of a yellow-
orange suspension containing a perzincated penta-
methylruthenocene (2, Scheme 1).7 Hydrolysis of 2 with
water afforded pentamethylruthenocene8a (3, 90%),
while D2O quench gave pentamethylruthenocene (95%)
with 86% deuterium incorporation. By contrast, 1 did
not react with water under similar conditions. These
results unambiguously confirm the complete replace-
ment of the carbon-mercury bonds of 1 with carbon-
zinc bonds. Treatment of 2 with iodine afforded
pentaiodopentamethylruthenocene8b (4, 88%). To gain
further insight, 2 was treated with methyl disulfide in
toluene at 111 °C for 6 days to afford pentakis(meth-
ylthio)pentamethylruthenocene (5, 69%). Analogous
treatment with methyl diselenide gave pentakis(meth-
ylseleno)pentamethylruthenocene (6, 50%).7 Exposure
of 1 to similar reaction conditions with methyl disulfide
or methyl diselenide gave only decomposition. As a
comparison, refluxing of the pentamagnesiated pentam-
ethylruthenocene3 in neat methyl disulfide afforded
(methylthio)pentamethylruthenocene (65%) and bis-
(methylthio)pentamethylruthenocene (16%).7 Treat-
(7) Complete preparative procedures and spectral and analytical
data for the new compounds are presented in the Supporting Informa-
tion. Preparation of 5: A 100-mL Schlenk flask was charged with 1
(0.500 g, 0.339 mmol) and toluene (50 mL). A 2.0 M solution of
dimethylzinc in toluene (2.03 mL, 4.06 mmol) was added to the
resulting suspension. The mixture was stirred for
2 h at room
temperature. Then methyl disulfide (1.00 mL, 11.1 mmol) was added,
and the mixture was refluxed for 6 days. After addition of water to
quench any remaining dimethylzinc, the volatile components were
removed under reduced pressure. The crude product was extracted with
dichloromethane (50 mL). The resultant extract was filtered through
a medium-porosity glass frit. The dichloromethane eluent was applied
to a 2.5 cm × 15 cm column of silica gel. Elution with toluene, followed
by removal of solvent under reduced pressure, afforded 5 as a light
yellow solid (0.125 g, 69%): dec point (sealed tube) 170 °C; 1H NMR
(CDCl3, δ) 1.72 (s, C5(CH3)5), 2.39 (s, C5(SCH3)5); 13C{1H} NMR (CDCl3,
ppm) 92.38 (s, C5(SCH3)5), 89.47 (s, C5(CH3)5), 20.69 (s, C5(SCH3)5),
10.08 (s, C5(CH3)5); MS (20 eV) m/e 532 (M+, 100%), 517 (M+ - CH3,
97%). Anal. Calcd for C20H30RuS5: C, 45.17; H, 5.69. Found: C, 44.59;
H, 5.66.
X Abstract published in Advance ACS Abstracts, May 15, 1997.
(1) For leading references, see: Winter, C. H.; Seneviratne, K. N.;
Bretschneider-Hurley, A. Comm. Inorg. Chem. 1996, 19, 1.
(2) Bretschneider-Hurley, A.; Winter, C. H. J . Am. Chem. Soc. 1994,
116, 6468.
(3) Seneviratne, K. N.; Bretschneider-Hurley, A.; Winter, C. H. J .
Am. Chem. Soc. 1996, 118, 5506.
(4) Bretschneider-Hurley, A.; Winter, C. H. Manuscript in prepara-
tion.
(5) See also: Morton, M. S.; Selegue, J . P. J . Am. Chem. Soc. 1995,
117, 7005.
(6) For a recent overview of organozinc chemistry, see: Erdik, E.
Organozinc Reagents in Organic Synthesis; CRC Press: Boca Raton,
FL, 1996.
(8) (a) Tilley, T. D.; Grubbs, R. H.; Bercaw, J . E. Organometallics
1984, 3, 274. (b) Winter, C. H.; Han, Y.-H.; Heeg, M. J . Organometallics
1994, 13, 3009.
S0276-7333(97)00125-8 CCC: $14.00 © 1997 American Chemical Society