Ruthenium(II) complexes with (2,4,6-cycloheptatrien-1-ylidene)ethenylidene ligands: Strongly polarized allenylidene complexes

Article abstract of DOI:10.1021/om9610556

The syntheses of cationic ruthenium(II) allenylidene complexes [(1a-e)PF₆] of the type [CpRu(=C=C=CR₂)(PPh₃)₂]PF₆ (1a, R₂C: = cycloheptatrienylidene; 1b, R₂C: = 2,7-dimethyl4,5-benzocycloheptatrienylidene; 1c, R₂C: = 2,7-diphenyl-4,5-benzocycloheptatrienylidene; 1d, R₂C: = dibenzo[a,e]cycloheptatrienylidene; 1e, R₂C: = 4,5-dihydrodibenzo[a,e]cycloheptatrienylidene) are reported. In the series 1a-e, the decreasing ability of R₂C: to stabilize a positive charge results in a tuning of the electronic and optical properties by changing the relative contributions of the two canonical forms [Ru⁺]=C=C=CR₂ (A) and [Ru]-C=C-CR₂⁺ (B), which is studied particularly by NMR and UV/visible spectroscopy. The first molecular hyperpolarizabilitiy β of (1b)PF₆ has been determined by hyper Raleigh scattering. The X-ray crystal structures of (1b)PF₆, (1d)PF₆·CH₂Cl₂, and the acetylide complex CpRu(C=C-C₇H₇-2,4,6)(PPh₃)₂ are presented.

Full text of DOI:10.1021/om9610556

1418
Organometallics 1997, 16, 1418-1424
Ru th en iu m (II) Com p lexes w ith
(2,4,6-Cycloh ep ta tr ien -1-ylid en e)eth en ylid en e Liga n d s:
Str on gly P ola r ized Allen ylid en e Com p lexes
Matthias Tamm*
Institut fu¨r Anorganische und Analytische Chemie, Freie Universita¨t Berlin,
Fabeckstrasse 34-36, D-14195 Berlin, Germany
Thomas J entzsch and Wolfgang Werncke
Max-Born-Institut fu¨r Nichtlineare Optik und Kurzzeitspektroskopie,
Rudower Chaussee 6, D-12489 Berlin, Germany
Received December 13, 1996X
The syntheses of cationic ruthenium(II) allenylidene complexes [(1a -e)PF6] of the type
[CpRu(dCdCdCR2)(PPh3)2]PF6 (1a , R2C: ) cycloheptatrienylidene; 1b, R2C: ) 2,7-dimethyl-
4,5-benzocycloheptatrienylidene; 1c, R2C: ) 2,7-diphenyl-4,5-benzocycloheptatrienylidene;
1d , R2C: ) dibenzo[a,e]cycloheptatrienylidene; 1e, R2C: ) 4,5-dihydrodibenzo[a,e]cyclo-
heptatrienylidene) are reported. In the series 1a -e, the decreasing ability of R2C: to stabilize
a positive charge results in a tuning of the electronic and optical properties by changing the
relative contributions of the two canonical forms [Ru+]dCdCdCR2 (A) and [Ru]sCtCsCR2
+
(B), which is studied particularly by NMR and UV/visible spectroscopy. The first molecular
hyperpolarizabilitiy â of (1b)PF6 has been determined by hyper Raleigh scattering. The
X-ray crystal structures of (1b)PF6, (1d )PF6‚CH2Cl2, and the acetylide complex CpRu(CtC-
C7H7-2,4,6)(PPh3)2 are presented.
In tr od u ction
others have reported on the syntheses of organometallic
mono-12 and bimetallic13 sesquifulvalene derivatives
exhibiting notably high first molecular hyperpolariz-
abilities â. In these polarizable, dipolar molecules,
In recent years, the chemistry of metallacumulenes
M(dC)ndCR2 incorporating ligands, which are higher
cumologs of alkylidene (n ) 0)1 and vinylidene com-
plexes (n ) 1),2 has increased significantly. Since the
discovery of the first allenylidene complexes (n ) 2) in
1976 by Fischer et al.3 and Berke,4 their number has
grown continuously, and several synthetic routes have
now been established.2,5 Another landmark in the
chemistry of highly unsaturated metallacumulenes was
the isolation of the first pentatetraenylidene complex
in 1994 by Touchard et al.,6 which was followed by
reports from Werner et al.7 and Roth and Fischer8 on
the first neutral transition-metal complexes of the type
MdCdCdCdCdCR2.
Besides their interesting chemical properties, com-
pounds containing linear unsaturated carbon chains9
are attractive due to their potential use in material
science, e.g. nonlinear optics.10 To the best of our
knowledge, the nonlinear optical properties of allen-
ylidenes and their higher cumologs have not yet been
studied, although the determination of the quadratic
nonlinearities of related acetylide ruthenium(II) com-
plexes proved to be very promising.11 Recently, we and
(5) For recent publications, see: (a) Touchard, D.; Guesmi, S.;
Bouchaib, M.; Haquette, P.; Daridor, A.; Dixneuf, P. H. Organometallics
1996, 15, 2579. (b) Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Gonza´lez-
Cueva, M.; Lastra, E.; Borge, J .; Garc´ıa-Granda, S.; Pe´rez-Carren˜o,
E. Organometallics 1996, 15, 2137. (c) Bruce, M. I.; Hinterding, P.;
Low, P. J .; Skelton, B. W.; White, A. H. Chem. Commun. 1996, 1009.
(d) Mart´ın, M.; Gevert, O.; Werner, H. J . Chem. Soc., Dalton Trans.
1996, 2275. (e) Werner, H.; Wiedemann, R.; Laubender, M.; Wolf, J .;
Windmu¨ller, B. Chem. Commun. 1996, 1413. (f) Touchard, D.; Pirio,
N.; Toupet, L.; Fettouhi, M.; Ouahab, L.; Dixneuf, P. H. Organome-
tallics 1995, 14, 5263. (g) Touchard, D.; Pirio, N.; Dixneuf, P. H.
Organometallics 1995, 14, 4920. (h) Peron, D.; Romero, A.; Dixneuf,
P. H. Organometallics 1995, 14, 3319. (i) Aumann, R.; J asper, B.;
Fro¨hlich, R. Organometallics 1995, 14, 3173. (j) Werner, H.; Stark, A.;
Steinert, P.; Gru¨nwald, C.; Wolf, J . Chem. Ber. 1995, 128, 49. (k)
Windmu¨ller, B.; Wolf, J .; Werner, H. J . Organomet. Chem. 1995, 502,
147. (l) Braun, T.; Steinert, P.; Werner, H. J . Organomet. Chem. 1995,
488, 169. (m) Werner, H.; Rappert, T.; Wiedemann, R.; Wolf, J .; Mahr,
N. Organometallics 1994, 13, 2721. (n) Schwab, P.; Werner, H. J . Chem.
Soc., Dalton Trans. 1994, 3415. (o) Cadierno, V.; Gamasa, M. P.;
Gimeno, J .; Lastra, E.; Borge, J .; Garc´ıa-Granda, S. Organometallics
1994, 13, 745. (p) Fischer, H.; Reindl, D.; Roth, G. Z. Naturforsch. 1994,
49b, 1207. (q) Pe´ron, D.; Romero, A.; Dixneuf, P. H. Gazz. Chim. Ital.
1994, 124, 497.
(6) Touchard, D.; Haquette, P.; Daridor, A.; Toupet, L.; Dixneuf, P.
H. J . Am. Chem. Soc. 1994, 116, 11157.
(7) Lass, R. W.; Steinert, P.; Wolf, J .; Werner, H. Chem.-Eur. J . 1996,
2, 19.
(8) Roth, G.; Fischer, H. Organometallics 1996, 15, 1139.
(9) Lang, H. Angew. Chem. 1994, 106, 569; Angew. Chem., Int. Ed.
Engl. 1994, 33, 547.
(10) Long, N. J . Angew. Chem. 1995, 107, 37; Angew. Chem., Int.
Ed. Engl. 1995, 34, 6.
X Abstract published in Advance ACS Abstracts, March 1, 1997.
(1) Do¨tz, K. H.; Fischer, H.; Hofmann, P.; Kreissl, F. R.; Schubert,
U.; Weiss, K. Transition Metal Carbene Complexes; VCH Publishers:
Weinheim, Germany, 1983.
(2) (a) Bruce, M. I. Chem. Rev. 1991, 91, 197. (b) Bruce, M. I.;
Swincer, A. G. Adv. Organomet. Chem. 1983, 22, 59.
(3) Fischer, E. O.; Kalder, H.-J .; Frank, A.; Ko¨hler, F. H.; Huttner,
G. Angew. Chem. 1976, 88, 683; Angew. Chem., Int. Ed. Engl. 1976,
15, 623.
(4) Berke, H. Angew. Chem. 1976, 88, 684; Angew. Chem., Int. Ed.
Engl. 1976, 15, 624.
(11) (a) Whittall, I. R.; Humphrey, M. G.; Persoons, A.; Houbrechts,
S. Organometallics 1996, 15, 1935. (b) McDonagh, A. M.; Whittall, I.
R.; Humphrey, M. G.; Skelton, B. W.; White, A. H. J . Organomet. Chem.
1996, 519, 229.
(12) (a) Tamm, M.; Grzegorzewski, A.; Steiner, T.; J entzsch, T.;
Werncke, W. Organometallics 1996, 15, 4984. (b) Tamm, M.; Grze-
gorzewski, A.; Bru¨dgam, I. J . Organomet. Chem. 1996, 519, 217.
S0276-7333(96)01055-2 CCC: $14.00 © 1997 American Chemical Society

Strongly Polarized Ru(II) Allenylidene Complexes
Organometallics, Vol. 16, No. 7, 1997 1419
F igu r e 1. Canonical presentations for (2,4,6-cyclohep-
tatrien-1-ylidene)ethenylidene.
cyclopentadienyl and cycloheptatrienyl metal fragments
are in a π-conjugated electron donor/acceptor arrange-
ment, which meets the requirements for the classical
design of organic compounds with large second har-
monic generation (SHG) efficiencies.14 Thus, the suit-
ability of the cycloheptatrienyl (tropylium) unit to act
as a strong electron acceptor in NLO compounds has
stimulated us to incorporate this structural feature into
metallacumulenes, and we have initiated a program to
synthesize allenylidene complexes of the type 1 with a
(2,4,6-cycloheptatrien-1-ylidene)ethenylidene ligand (Fig-
ure 1) and derivatives thereof. Complexes of related
carbenes such as cycloheptatrienylidene have been
studied by J ones and co-workers.15
F igu r e 2. Canonical presentations for cationic ruthenium-
(II) allenylidene complexes 1a -e.
Sch em e 1a
Generally, the structural parameters in allenylidene
complexes indicate a substantial contribution from two
different mesomeric structures, MdCdCdCR2 (A) and
+
M--CtC-CR2 (B).5 In 1, the well-known ability of
the tropylium system to effectively stabilize a positive
charge16 should lead to compounds with strong dipolar
characteristics (canonical form B), possibly resulting in
interesting physicochemical properties. Furthermore,
coordination of the seven-membered cycloheptatrienyl
ring to other transition-metal fragments17 offers the
option to synthesize heterobimetallic metallacumulenes
and to study electronic and magnetic interaction through
these new ligands.
In this contribution, we report on the syntheses and
characterization of several cationic complexes [(1)PF6]
of the type [CpRu(dCdCdCR2)(PPh3)2]PF6 (Figure 2),
containing various (cycloheptatrienylidene)ethenylidene
ligands, R2CdCdC:, with R2C: ranging from cyclohep-
tatrienylidene in 1a to 4,5-benzocycloheptatrienylidenes
in 1b,c and dibenzo[a,e]cycloheptatrienylidene in 1d .
Complex 1e was synthesized for reasons of comparison
and contains a 4,5-dihydrogenated ligand, which can be
regarded as a “true” allenylidene.
a
Reagents: (i) CpRu(PPh3)2Cl, NH4PF6, MeOH.
vation of propargyl alcohols by electron-rich metal
fragments.5a,b,d-h, j-q,18 Thus, the alkynols 2b-e (Scheme
1) are suitable starting materials for the syntheses of
the cationic complexes 1b-e. They were obtained by
1,2-addition of (trimethylsilyl)acetylene to the corre-
sponding ketones19 and consecutive desilylation in
methanolic KOH solution.20 The alkynols are white
crystalline solids and are stable at ambient tempera-
ture.21 The X-ray crystal structures of 2c,d have been
reported elsewhere.22 The reaction of CpRu(PPh3)2Cl
with the alcohols 2 and NH4PF6 in methanol (room
temperature, 15 h) led to deeply red to blue colored
solutions (Scheme 1). After evaporation of the solvent,
extraction with dichloromethane, and precipitation with
diethyl ether, complexes (1b-e)PF6 were obtained
analytically pure in high yield.
Resu lts a n d Discu ssion
Syn th eses. The most straightforward method of
The route outlined in Scheme 1 could not be applied
to the synthesis of 1a , as tropone (cycloheptatrienone)
is resistant toward 1,2-additions due to aromatic sta-
bilization.23 Alternatively, 7-ethynyl-1,3,5-cyclohep-
tatriene (3) synthesized by addition of HCtCMgBr to
7-methoxy-1,3,5-cycloheptatriene24 seemed to be a prom-
ising starting material. The acetylide ruthenium(II)
access to allenylidene complexes is the direct acti-
(13) (a) Behrens, U.; Brussard, H.; Hagenau, U.; Heck, J .; Hendrickx,
E.; Ko¨rnich, J .; van der Linden, J . G. M.; Persoons, A.; Spek, A. L.;
Veldman, N.; Voss, B.; Wong, H. Chem.-Eur. J . 1996, 2, 98. (b) Tamm,
M.; Grzegorzewski, A.; Steiner, T. Chem. Ber. 1997, 130, 225.
(14) (a) Williams, D. J . Angew. Chem. 1984, 96, 637; Angew. Chem.,
Int. Ed. Engl. 1984, 23, 690. (b) Chemla, D. S.; Zyss, J . Nonlinear
Optical Properties of Organic Molecules and Crystals; Academic
Press: Orlando, FL, 1987. (c) Burland, D. M. Chem. Rev. 1994, 94, 1.
(d) Marks, T. J .; Ratner, M. A. Angew. Chem. 1995, 107, 167; Angew.
Chem., Int. Ed. Engl. 1995, 34, 155.
(15) (a) Riley, P. E.; Davies, R. E.; Allison, N. T.; J ones, W. M. Inorg.
Chem. 1982, 21, 1321. (b) Manganiello, F. J .; Radcliffe, M. D.; J ones,
W. M. J . Organomet. Chem. 1982, 228, 273. (c) Riley, P. E.; Davies, R.
E.; Allison, N. T.; J ones, W. M. J . Am. Chem. Soc. 1980, 102, 2458. (d)
Allison, N. T.; Kawada, Y.; J ones, W. M. J . Am. Chem. Soc. 1978, 100,
5226. See also: (e) Klosin, J .; Zheng, X.; J ones, W. M. Organometallics
1996, 15, 3788. (f) Matzinger, S.; Bally, T.; Patterson, E. V.; McMahon,
R. J . J . Am. Chem. Soc. 1996, 118, 1535. (g) Hoffmann, R. W.; Lotze,
M.; Reiffen, M.; Steinbach, K. Liebigs Ann. Chem. 1981, 581.
(16) Asao, T.; Oda, M. In Methoden der Organischen Chemie
(Houben-Weyl); Kropf, H., Ed.; Georg Thieme Verlag: Stuttgart,
Germany, 1985; Vol. V/2c, p 49.
(18) Selegue, J . P. Organometallics 1982, 1, 217.
(19) Brandsma, L. Preparative Acetylenic Chemistry, 2nd ed.; Elsevi-
er: Amsterdam, 1988.
(20) Takahashi, S.; Kuroyama, Y.; Sonogashira, K.; Hagihara, N.
Synthesis 1980, 627.
(21) It has to be noted that especially in the case of 2b, occasional
slow decomposition in solution with re-formation of the ketone and
evolution of acetylene was observed. After heating of solutions of 2b
in diethyl ether for several hours, the 2,7-dimethyl-4,5-benzotropone
was isolated quantitatively.
(22) (a) Steiner, T.; Tamm, M.; Lutz, B.; van der Maas, J . Chem.
Commun. 1996, 1127. (b) Steiner, T.; Starikov, E. B.; Tamm, M. J .
Chem. Soc., Perkin Trans. 2 1996, 67.
(23) Pietra, F. Chem. Rev. 1973, 73, 293.
(17) Green, M. L. H.; Ng, D. K. P. Chem. Rev. 1995, 95, 439.
(24) Hoskinson, R. M. Aust. J . Chem. 1970, 23 399.

1420 Organometallics, Vol. 16, No. 7, 1997
Tamm et al.
Sch em e 2a
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for (1b)P F 6, (1d )P F 6‚CH2Cl2, a n d 4
1b
1d
4
Ru-P1
Ru-P2
Ru-C1
C1-C2
C2-C3
C3-C4
C3-C9
C4-C5
C5-C6
C6-C7
C7-C8
C8-C9
Ru-C(Cp)
2.326(3)
2.324(3)
1.94(1)
1.23(2)
1.42(2)
1.42(2)
1.43(2)
1.35(2)
1.40(2)
1.39(2)
1.45(2)
1.34(2)
2.22(1)-
2.29(1)
2.3400(9)
2.3470(9)
1.895(3)
1.267(4)
1.352(4)
1.480(4)
1.469(5)
1.414(5)
1.456(5)
1.333(5)
1.440(5)
1.420(5)
2.231(3)-
2.280(3)
2.283(3)
2.288(3)
2.03(1)
1.19(1)
1.50(2)
1.48(2)
1.48(2)
1.30(2)
1.42(2)
1.32(2)
1.40(2)
1.33(2)
2.22(1)-
2.24(2)
Ru-C1-C2
C1-C2-C3
C2-C3-C4
C2-C3-C9
P1-Ru-P2
C1-Ru-P1
C1-Ru-P2
170(1)
174(1)
119(1)
115(1)
101.6(1)
91.1(3)
93.0(3)
171.3(3)
172.4(3)
117.7(3)
118.1(3)
96.66(3)
89.15(9)
97.6(1)
173(1)
173(1)
114(1)
114(1)
100.5(1)
89.9(3)
90.6(3)
a
Reagents: (i) (1) CpRu(PPh3)2Cl, MeOH, (2) Na; (ii)
CpRu(PPh3)2Cl, NH4PF6, MeOH.
3 by hydride abstraction. 5 is obtained as a white
crystalline solid, which has to be kept in the cold under
an argon atmosphere, as it appears to be considerably
more sensitive than substituted alkynyltropylium salts
of the type (RCtC-C7H6)+X-.28 The ethynyltropylium
cation is the conjugate acid of (2,4,6-cycloheptatrien-1-
ylidene)ethenylidene (Figure 1), and we are currently
studying the possibility to generate the free allenylidene
by deprotonation of 5 with appropriate non-nucleophilic
bases.
The addition of sodium trimethylsilanolate proceeded
smoothly to give a mixture of the isomeric silyl ethers
6, which could be purified by Kugelrohr destillation.
These protected alcohols reacted rapidly with a metha-
nolic suspension of CpRu(PPh3)2Cl in the presence of
NH4PF6 to form (1a )PF6 as deep violet-blue crystals.
F igu r e 3. ORTEP drawing of 4. Only the ipso-carbon
atoms of the PPh3 ligands are shown.
complex 4 was prepared according to the route devel-
oped by Bruce et al.25 via the cycloheptatrienylvi-
nylidene complex (Scheme 2). The yellow crystals thus
obtained were subjected to an X-ray diffraction analysis,
and the molecular structure is shown in Figure 3. The
central ruthenium atom in 4 is pseudooctahedrally
coordinated, and the bond lengths and angles fall in the
range observed for other complexes, such as CpRu-
(CtCPh)(PPh3)2 (Table 1).26
However, the reaction of 4 with triphenylcarbenium
tetrafluoroborate, (Ph3C)BF4, proved to be more complex
than anticipated. Although the reaction mixture was
not fully characterized, it is evident, for instance from
mass spectroscopy, that to some extent the triphenyl-
carbenium cation reacts with 4 by adding to the basic
Câ carbon atom to form a vinylidene complex rather
than abstracting a hydride to give (1a )BF4. Analo-
gously, formation of a cycloheptatrienylvinylidene com-
plex by addition of C7H7+ to CpRu(CtCPh)(PPh3)2 has
been reported earlier.27
Str u ctu r al Ch ar acter ization of Allen yliden e Com -
p lexes (1b)P F 6 a n d (1d )P F 6‚CH2Cl2. The molecular
structures of the cations 1b (top) and 1d (bottom) are
depicted in Figure 4. The ruthenium atoms are pseu-
dooctahedrally coordinated, with the allenylidene ligands
bound in a linear fashion. Unfortunately, due to severe
disorder of the hexafluorophosphate anion in (1b)PF6,
the structure could only be refined with reduced ac-
curacy, not allowing a reasonable comparison of the
structural parameters of both cations. In 1d , the
observed distances in the metallacumulene chain Ru-
C1-C2-C3 (Table 1) fall in the range shown by other
ruthenium(II) allenylidene complexes,5b,o,18 indicating
contribution of the two canonical forms [Ru+]dCdCdCR2
(A) and [Ru]sCtCsCR2+ (B) (Figure 2). The dibenzo-
[a,e]cycloheptatrienylidene unit adopts a boat conforma-
tion owing to repulsion between C3 and the peri
hydrogens.29 In contrast, the (2,7-dimethyl-4,5-benzo-
cycloheptatrienylidene)ethenylidene ligand in 1b is
planar and forms a dihedral angle of 21.5(8)° with the
pseudomirror plane including C1, Ru, and the centroid
The successful strategy for the high-yield synthesis
of (1a )PF6 is also outlined in Scheme 2. Hence, ethy-
nyltropylium tetrafluoroborate (5) was synthesized from
(25) (a) Bruce, M. I.; Hameister, C.; Swincer, A. G.; Wallis, R. C.
Inorg. Synth. 1982, 21, 78. (b) Bruce, M. I.; Wallis, R. C. Aust. J . Chem.
1979, 32, 1471.
(26) (a) Wisner, J . M.; Bartczak, T. J .; Ibers, J . A. Inorg. Chim. Acta
1985, 100, 115. (b) Bruce, M. I.; Humphrey, M. G.; Snow, M. R.;
Tiekink, E. R. T. J . Organomet. Chem. 1986, 314, 213.
(27) Bruce, M. I.; Humphrey, M. G.; Koutsantonis, G. A.; Liddell,
M. J . J . Organomet. Chem. 1987, 326, 247.
(28) J utz, C.; Voithenleitner, F. Chem. Ber. 1964, 97, 1337.
(29) (a) Lindner, H. J .; Hafner, K.; Romer, M.; von Gross, B. Liebigs
Ann. Chem. 1975, 731. (b) Dichmann, K. S.; Nyburg, S. C.; Pickard, F.
H.; Potworowski, J . A. Acta Crystallogr., Sect. B 1974, 30, 27. (c)
Shimanouchi, H.; Hata, T.; Sasada, Y. Tetrahedron Lett. 1968, 3573.

Strongly Polarized Ru(II) Allenylidene Complexes
Organometallics, Vol. 16, No. 7, 1997 1421
Ta ble 2. Selected 13C a n d 1H NMR Reson a n ces for
Com p lexes (1a -e)P F 6
compd
Ru-CR
Câ
Cγ
C5H5
C5H5
1a
1b
1c
1d
1e
235.4
257.1
274.0
293.1
296.7
168.2
181.2
204.8
211.7
214.7
153.3
151.6
151.7
158.5
162.3
90.4
91.3
92.9
93.0
93.6
4.75
4.83
4.15
5.05
5.09
Ta ble 3. IR a n d UV/Visible Da ta for Com p lexes
(1a -e)P F 6
λ
max, nm
CH3CN
ν˜(CCC),
∆ν˜,
compd
cm-1
CHCl3
cm-1 a
1a
1b
1c
1d
1e
1971
1941
1920
1928
1925
557
596
611
562
502
550
590
601
555
496
-230
-170
-270
-220
-240
a
∆ν˜ ) ν˜max(CHCl3) - ν˜max(CH3CN).
dienyl resonances (Table 2) indicates that the π-acceptor
capabilities of the ligands in 1 decrease in the order 1e
> 1d > 1b > 1a , as a direct relationship between the
chemical shift of the cyclopentadienyl group and the
degree of electron richness at the metal site has been
suggested.18,31 The high-field shift of the Cp protons in
1c relative to the other complexes is probably due to
shielding by the two phenyl groups. The IR spectra of
1a -e exhibit strong absorptions for the asymmetric ν-
(CCC) stretching frequency in the range 1920 (1c)-1971
(1a ) cm-1, clearly confirming their metallacumulene
nature (Table 3). Although the spectroscopic properties
of complexes 1a -e differ significantly within a consider-
ably wide range, the ligands in all compounds are still
best described as allenylidene rather than acetylide
ligands. This conclusion is supported by comparison
with the spectroscopic data found for ruthenium(II)
acetylide complexes,5b,c,25 e.g., 4, which shows a triplet
(2J PC ) 21 Hz) at 93.6 ppm for CR and a singlet at 111.9
ppm for Câ in the 13C NMR spectrum and an infrared
F igu r e 4. ORTEP drawings of the cations in (1b)PF6 (top)
and (1d )PF6‚CH2Cl2 (different perspective views). Only the
ipso-carbon atoms of the PPh3 ligands are shown.
of the cyclopentadienyl ring, which slightly deviates
from the theoretically expected coplanarity.30
Sp ectr oscop ic Ch a r a cter iza tion of Allen ylid en e
Com p lexes (1a -e)P F 6. All complexes (1a -e)PF6 are
indefinitely stable in air and have been fully character-
ized by microanalyses and by infrared, UV/visible, mass,
and NMR (1H, 13C) spectroscopy. As mentioned above,
the bonding in the cations 1 can be described by the
two limiting resonance structures A and B shown
in Figure 2. Variation of the R2C: moiety in the
R2CdCdC: ligand allows tuning of the electronic and
optical properties of the respective allenylidene com-
plexes by changing the relative contributions of these
two canonical forms. In 1a , the positive charge is most
strongly stabilized by the cycloheptatrienyl unit, and
the ligand can be regarded as an ylidic “tropyli-
umacetylide” as expressed by B. Annelation of one or
two benzene rings in 1b,c or 1d , respectively, decreases
the stability of the tropylium system,16 shifting the
electronic structure from B to the more metallacumu-
lene-like state A.
ν(CtC) absorption at 2086 cm-1
.
Complexes 1a -e are intensely colored compounds.
Owing to the charge-transfer excitation represented by
the resonance structures A and B (Figure 2), their
ultraviolet/visible spectra exhibit a strong and broad
band centered at about 500-600 nm (Table 3), with the
longest wavelength absorption being observed for 1c.
This trend in λmax indicates that both canonical forms
contribute significantly to the ground-state electronic
structure of 1a -e and are nearly balanced in 1c.32
Destabilization of the tropylium sytem causes a meso-
meric shift from B to A, which is in agreement with the
conclusions drawn from the discussion of the NMR data.
Furthermore, the complexes only show moderate nega-
tive solvatochromism upon changing the solvent from
chloroform to acetonitrile (∆ν˜ ranging from -170 to
-270 cm-1, Table 3).
In view of the promising results obtained with ses-
quifulvalene complexes,12,13 we were encouraged to
determine the first molecular hyperpolarizablities â of
complexes (1)PF6 using the hyper Raleigh scattering
This trend is easily confirmed by evaluation of the
13C NMR spectra (Table 2). Whereas the CR and Câ
resonances observed for 1e and 1d can be compared
to those shown by other isoelectronic allenylidene
complexes,5b,o these resonances are found at consecu-
tively higher field in the spectra of 1c, 1b, and 1a .
(31) (a) Bruce, M. I.; Wong, F. S. J . Organomet. Chem. 1981, 210,
C5. (b) Treichel, P. M.; Komar, D. A. Synth. React. Inorg. Met.-Org.
Chem. 1980, 10, 205.
1
Accordingly, comparison of the H and 13C cyclopenta-
(32) (a) Reichardt, C. Chem. Rev. 1994, 94, 2319. (b) Reichardt, C.
Solvents and Solvent Effects in Organic Chemistry; VCH Publishers:
Weinheim, 1988.
(30) Schilling, B. E. R.; Hoffmann, R.; Lichtenberger, D. L. J . Am.
Chem. Soc. 1979, 101, 585.

1422 Organometallics, Vol. 16, No. 7, 1997
Tamm et al.
technique.33 Usually, this experiment is performed with
a Nd:YAG laser (λ ) 1064 nm), and the frequency-
doubled scattered light (λ/2 ) 532 nm) is measured. All
complexes (1)PF6 still absorb strongly at 532 nm, and
it proved to be difficult to measure the intensity of the
scattered light. However, as (1b)PF6 and (1c)PF6 have
the smallest absorption at 532 nm and are essentially
electronically identical, we determined only the first
molecular hyperpolarizability of (1b)PF6 in acetonitrile,
giving â ) 120 × 10-30 esu. Using the two-level model,34
a static hyperpolarizablity âo ) 19 × 10-30 esu can be
calculated, but it should be noted that, in our case, this
simple model is not a versatile tool, as the frequency-
doubled scattered light is still in the region of very
strong absorption. Separation of resonance enhance-
ment contributions would require the determination of
â at a different basic laser wavelength.
The â value reported here is reasonably high com-
pared to those of organic35 and organometallic10,36
compounds of comparable chromophor length, but it is
smaller than those measured for ruthenium(II) acetylide
complexes, e.g., CpRu(CtCC6H4NO2-4)(PPh3)2 (â(THF)
) 468 × 10-30 esu, λmax(THF) ) 460 nm).11 We assume
that this enhanced second harmonic generation ef-
ficiency is mainly caused by the larger dipole moment
difference ∆µeg between the ground state (g) and excited
state (e) of the respective CT excitation. According to
the two-level model,34 this results in a higher static
hyperpolarizability âo, outweighing the increasing effect
of a lower energy of transition hωeg on âo.37 To obtain
metallacumulenes, which are more suitable for nonlin-
ear optical applications, the following efforts seem to
be promising: (a) extension of the metallacumulene
chain,6-8 (b) variation or tuning of the transition metal
fragment to achieve the desired optical transparency for
frequency-doubling experiments,12a and (c) synthesis of
heterobimetallic complexes to induce an additional
ligand-to-metal charge transfer.
Exp er im en ta l Section
All operations were performed in an atmosphere of dry
argon by using Schlenk and vacuum techniques. Solvents
were dried by standard methods and distilled prior to use.
NMR spectra were recorded on a Bruker AM 250 (250 MHz)
instrument. Infrared spectra were taken on a Perkin-Elmer
983 instrument. Elemental analyses (C,H,N) were performed
at the Freie Universita¨t Berlin on a Heraeus CHN-Rapid
elemental analyzer. Mass spectra were recorded on a Varian
MAT 711 instrument and UV/vis spectra on a Perkin-Elmer
Lambda 9 UV/visible/near-IR spectrophotometer using 10-3
M
solutions. CpRu(PPh3)2Cl,40 and 7-ethynyl-1,3,5-cyclohep-
tatriene24 were prepared according to published procedures.
The alkynols 2b-e were synthesized as described in ref 22b.
Syn th esis of (1a -e)P F 6. Gen er a l P r oced u r e. A suspen-
sion of CpRu(PPh3)2Cl (720 mg, 1 mmol) and NH4PF6 (200 mg,
1.2 mmol) in 80 mL of methanol was treated with the
corresponding alcohol (1.2 mmol); in the case of (1a )PF6, the
mixture of silyl ethers 6 was used. Stirring was continued
for 15 h, and the solvent was removed in vacuo. The remain-
ing solid was extracted with dichloromethane, and the filtered
solution was concentrated to ca. 10 mL. Addition to rapidly
stirred diethyl ether (100 mL) precipitated the complexes as
intensely colored solids, which were washed with Et2O and
dried in vacuo. Yields ranged from 75 to 90%.
(1a )P F 6. 1H NMR (CDCl3, 250 MHz): δ 7.33 (m, 6H, C7
CH), 7.17 (m, 30H, C6H5), 4.75 (s, 5H, C5H5). 13C{1H} NMR
2
(CD2Cl2, 62.90 MHz): δ 235.4 (t, J PC ) 20 Hz, Ru-C), 168.2
(Ru-CC), 153.3 (Ru-CCC), 152.1, 142.5, 140.7 (C7 CH), 136.4
1
2
(m, J PC ) 24 Hz, P-C), 133.9 (t, J PC ) 4 Hz, P-CC), 130.2
3
(P-CCCC), 128.4 (t, J PC ) 4 Hz, P-CCC), 90.4 (C5H5). IR
(KBr): ν(CCC) 1971 cm-1. MS (FAB): m/z (relative intensity)
805 (3.4) [M+], 691 (3.1) [(CpRu(PPh3)2)+], 543 (5.1) [(M -
PPh3)+], 429 (17.4) [(CpRuPPh3)+]. UV/vis (CHCl3): λmax (ꢀ)
557 (19 810) nm (L mol-1 cm-1). UV/vis (CH3CN): λmax (ꢀ) 550
(17 940) nm (L mol-1 cm-1). Anal. Calcd for C50H41F6P3Ru
(Mr ) 949.86): C, 63.23; H, 4.35. Found: C, 63.07; H, 4.57.
(1b)P F 6. 1H NMR (CDCl3, 250 MHz): δ 8.28 (s, 2H, C7 CH),
7.88 (m, 2H, C6 CH), 7.77 (m, 2H, C6 CH), 7.33 (t, 6H,
PCCCCH), 7.16 (m, 24H, PCCH + PCCCH), 4.83 (s, 5H, C5H5),
2.56 (s, 6H, CH3). 13C{1H} NMR (CD2Cl2, 62.90 MHz): δ 257.1
2
(t, J PC ) 19 Hz, Ru-C), 181.2 (Ru-CC), 151.6 (Ru-CCC),
The (2,4,6-cycloheptatrien-1-ylidene)ethenylidene
ligand (Figure 1) introduced in this contribution repre-
sents the prototype for the design of heterobimetallic
allenylidene complexes. The development of a general
coordination chemistry based on ligands derived thereof
is of interest with regard to electronic and magnetic
interactions between different metal sites through this
ligand. This coupling might differ significantly from
those of other complexes with σ,π-hydrocarbon bridges,38
such as ferrocenylacetylide,39 and we will report on
these results in due course.
149.0 (CCH3), 142.2 (C7 CH), 137.8 (CH-C-CH), 136.5 (m,
1J PC ) 23 Hz, P-C), 134.1 (C6 CH), 133.5 (t, J PC ) 5 Hz,
2
P-CC), 132.1 (C6 CH), 130.5 (P-CCCC), 128.6 (t, 3J PC ) 4 Hz,
P-CCC), 91.3 (C5H5), 29.3 (CH3). IR (KBr): ν(CCC) 1941
cm-1. MS (FAB): m/z (relative intensity) 883 (11.6) [M+], 429
(25.6) [(CpRuPPh3)+]. UV/vis (CHCl3): λmax (ꢀ) 596 (49 160)
nm (L mol-1 cm-1). UV/vis (CH3CN): λmax (ꢀ) 590 (38 770) nm
(L mol-1 cm-1). Anal. Calcd for C56H47F6P3Ru (Mr
)
1027.97): C, 65.43; H, 4.61. Found: C, 64.82; H, 5.34.
(1c)P F 6. 1H NMR (CDCl3, 250 MHz): δ 7.90 (s, 2H, C7 CH),
7.78 (m, 2H, C6 CH), 7.69 (m, 2H, C6 CH), 7.64 (d, 4H, C6 CH),
7.31 (m, 12H, C6 CH + PCCCCH), 7.16 (t, 12H, PCCCH), 6.74
(m, 12H, PCCH), 4.15 (s, 5H, C5H5). 13C{1H} NMR (CD2Cl2,
62.90 MHz): δ 274.0 (t, 2J PC ) 18 Hz, Ru-C), 204.8 (Ru-CC),
153.4 (CH), 151.7 (Ru-CCC), 145.1, 140.0 (CH), 137.3 (CH-
(33) (a) Clays, K.; Persoons, A. Phys. Rev. Lett. 1991, 66, 2980. (b)
Clays, K.; Persoons, A. Rev. Sci. Instrum. 1992, 63, 3285.
(34) (a) Oudar, J . L.; Chemla, D. S. J . Chem. Phys. 1977, 66, 2664.
(b) Hendrickx, E.; Clays, K.; Persoons, A.; Dehu, C.; Bredas, J . L. J .
Am. Chem. Soc. 1995, 117, 3547.
(35) (a) Cheng, L.-T.; Tam, W.; Stevenson, S. H.; Meredith, G. R.;
Rikken, G.; Marder, S. R. J . Phys. Chem. 1991, 95, 10631. (b) Cheng,
L.-T.; Tam, W.; Marder, S. R.; Stiegman, A. E.; Rikken, G.; Spangler,
C. W. J . Phys. Chem. 1991, 95, 10643.
(36) (a) Kanis, D. R.; Ratner, M. A.; Marks, T. J . Chem. Rev. 1994,
94, 195. (b) Yuan, Z.; Taylor, N. J .; Sun, Y.; Marder, T. B.; Williams,
I. D.; L.-T.; Cheng J . Organomet. Chem. 1993, 449, 27. (c) Loucif-Saibi,
R.; Delaire, J . A.; Bonazzola, L. Chem. Phys. 1992, 167, 369. (d)
Calabrese, J . C.; Cheng, L.-T.; Green, J . C.; Marder, S. R.; Tam, W. J .
Am. Chem. Soc. 1991, 113, 7227.
1
C-CH), 136.1 (m, J PC ) 25 Hz, P-C), 134.1 (CH), 133.3 (t,
2J PC ) 5 Hz, P-CC), 131.6 (CH), 130.4 (P-CCCC), 129.4, 129.0
3
(CH), 128.6 (t, J PC ) 5 Hz, P-CCC), 92.9 (C5H5). IR (KBr):
ν(CCC) 1920 cm-1. MS (FAB): m/z (relative intensity) 1007
(40.9) [M+], 744 (33.5) [(M - PPh3)+], 429 (100) [(CpRuPPh3)+].
UV/vis (CHCl3): λmax (ꢀ) 611 (32 500) nm (L mol-1 cm-1). UV/
vis (CH3CN): λmax (ꢀ) 601 (30 240) nm (L mol-1 cm-1). Anal.
Calcd for C66H51F6P3Ru (Mr ) 1152.11): C, 68.81; H, 4.46.
Found: C, 69.02; H, 5.15.
(37) (a) Ledoux, I.; Zyss, J .; J utand, A.; Amatore, C. Chem. Phys.
1991, 150, 117. (b) Marder, S. R.; Beratan, D. N.; Cheng, L.-T. Science
1991, 252, 103.
(38) Beck, W.; Niemer, B.; Wieser, M. Angew. Chem. 1993, 105, 969;
Angew. Chem., Int. Ed. Engl. 1993, 32, 923.
(39) (a) Sato, M.; Hayashi, Y.; Kumakura, S.; Shimizu, N.; Katada,
M.; Kawata, S. Organometallics 1996, 15, 721. (b) Sato, M.; Mogi, E.;
Katada, M. Organometallics 1995, 14, 4837 and references cited
therein.
(40) Bruce, M. I.; Windsor, N. J . Aust. J . Chem. 1977, 30, 1601.

Strongly Polarized Ru(II) Allenylidene Complexes
Organometallics, Vol. 16, No. 7, 1997 1423
Ta ble 4. Cr ysta llogr a p h ic Da ta for (1b)P F 6, (1d )P F 6‚CH2Cl2 a n d 4
1b
1d
4
cryst size, mm
formula
fw
0.40 × 0.20 × 0.20
C56H47F6P3Ru
1027.98
0.35 × 0.25 × 0.10
C59H47Cl2F6P3Ru
1134.92
0.25 × 0.12 × 0.12
C50H42P2Ru
805.92
wavelength, Å
cryst syst
space group
a, Å
b, Å
c, Å
0.710 73
0.710 73
triclinic
0.710 73
monoclinic
P21/n (No. 14)
10.100(3)
14.083(2)
35.822(5)
monoclinic
P21/n (No. 14)
9.729(2)
25.647(5)
18.039(3)
P1h (No. 2)
10.104(2)
13.276(2)
19.598(3)
93.71(1)
90.74(2)
108.55(1)
2486(2)
R, deg
â, deg
92.03(2)
92.29(1)
γ, deg
V, Å3
5092(3)
4
1.341
4498(3)
4
1.190
Z
F
2
calcd, g/cm3
1.516
5.733
µ, mm-1
4.495
4.403
θ range, deg
index ranges
1.0 e θ e 22.5
0 e h e 10
0 e k e 15
-38 e l e 38
7407
2.3 e θ e 22.5
-10 e h e 8
0 e k e 14
-20 e l e 20
4941
2.0 e θ e 22.5
0 e h e 10
0 e k e 27
-19 e l e 19
6455
no. of rflns collected
no. of independent rflns
no. of observed rflns
6639
5024
4527
3996
5884
3526
2
[Fo g 3σ(Fo2)]
no. of params
R, %
Rw, %
598
8.92
12.70
640
2.33
3.30
478
6.12
8.89
(1d )P F 6. 1H NMR (CDCl3, 250 MHz): δ 7.82 (d, 2H, C6 CH),
7.71 (t, 2H, C6 CH), 7.54 (d, 2H, C6 CH), 7.39 (t, 2H, C6 CH),
7.30 (t, 6H, PCCCCH), 7.25 (s, C7 CH), 7.06 (m, 24H, PCCH
+ PCCCH), 5.05 (s, 5H, C5H5). 13C{1H} NMR (CD2Cl2, 62.90
MHz): δ 293.1 (t, 2J PC ) 19 Hz, Ru-C), 211.7 (Ru-CC), 158.5
(Ru-CCC), 144.9 (Ru-CCCC), 135.6 (m, 1J PC ) 25 Hz, P-C),
135.5 (CHdCH-C), 133.3 (t, 2J PC ) 5 Hz, P-CC), 133.1, 132.1,
131.9, 131.5 (CH), 130.8 (P-CCCC), 129.9 (CH), 128.6 (t, 3J PC
[(PPh3)+]. Anal. Calcd for C50H42P2Ru (Mr ) 805.90): C,
74.52; H, 5.25. Found: C, 73.74; H, 5.48.
Syn th esis of 5. To a solution of 3 (5.0 g, 43 mmol) in 40
mL of dichloromethane was slowly added a solution of triph-
enylcarbenium tetrafluoroborate (14.0 g, 42 mmol) at -78 °C.
Stirring was continued at low temperature for 2 h. The
ethynyltropylium salt 5 was isolated by filtration under argon
and washed with CH2Cl2 and diethyl ether. 5 was obtained
as a white crystalline solid, which had to be kept under argon
in a refrigerator to avoid decomposition. Yield: 3.0 g (35%).
1H NMR (CD3CN, 250 MHz): δ 9.13 (m, 6H, C7 CH), 4.80 (s,
1H, CtCH). 13C{1H} NMR (CD3CN, 62.90 MHz): δ 158.1,
156.5, 154.7 (C7 CH), 150.8 (CCtCH), 97.4, 84.4 (CtC). IR
(KBr): ν(CtC) 2102 cm-1. MS (FAB): m/z (relative intensity)
115 (3.5) [M+]. Anal. Calcd for C9H7BF4 (Mr ) 201.96): C,
53.53; H, 3.49. Found: C, 52.06; H, 4.44.
Syn th esis of 6. To a suspension of 5 (3.79 g, 19 mmol) in
80 mL of dichloromethane was added NaOSiMe3 (19 mL of a
1 M solution in CH2Cl2). After the mixture was stirred
overnight, the solvent was removed in vacuo, and the residue
was extracted with hexane and filtered. After evaporation of
the solvent, the remaining oil was purified by Kugelrohr
destillation at 100 °C. The mixture of silyl ethers 6 was
obtained as a yellowish oil. Yield: 1.6 g (42%). No attempt
was made to fully interpret the NMR spectra. MS (EI, 70
eV): m/z (relative intensity) 204 (4.5) [M+], 203 (6.0) [(M -
H)+], 189 (100) [(M - CH3)+], 115 (90.5) [(M - OSiMe3)+], 73
(52.7) [(OSiMe3)+].
X-r a y Str u ctu r a l Deter m in a tion of (1b)P F 6, (1d )P F 6‚-
CH2Cl2, a n d 4. Crystals of (1d )PF6‚CH2Cl2 are air sensitive
(loss of solvent), while (1b)PF6 and 4 are airstable. A suitable
specimen of (1d )PF6‚CH2Cl2 was selected at -120 °C using a
device similar to that described by Veith and Ba¨rnighausen41
and mounted in the cold stream [-120(2) °C] of an Enraf-
Nonius CAD-4 diffractometer. Crystals of (1b)PF6 and 4 were
selected in air and mounted at room temperature on an Enraf-
Nonius CAD-4 diffractometer. Important crystal and data
collection details are listed in Table 4. Data for all com-
pounds were collected using ω-2θ scans. Raw data were
reduced to structure factors42 (and their esd’s) by correcting
for scan speed, Lorentz, and polarization effects. No crystal
) 4 Hz, P-CCC), 93.0 (C5H5). IR (KBr): ν(CCC) 1928 cm-1
.
MS (FAB): m/z (relative intensity) 905 (5.6) [M+], 643 (6.1)
[(M - PPh3)+], 429 (6.9) [(CpRuPPh3)+]. UV/vis (CHCl3): λmax
(ꢀ) 562 (21 390) nm (L mol-1 cm-1). UV/vis (CH3CN): λmax (ꢀ)
555 (21 170) nm (L mol-1 cm-1). Anal. Calcd for C58H45F6P3-
Ru‚CH2Cl2 (Mr ) 1134.91): C, 62.44; H, 4.17. Found: C, 62.71;
H, 4.53.
(1e)P F 6. 1H NMR (CDCl3, 250 MHz): δ 7.54 (t, 4H, CH),
7.32 (t, 6H PCCCCH), 7.23 (d, 2H, CH), 7.19 (d, 2H, CH), 7.08
(m, 24H, PCCH + PCCCH), 5.09 (s, 5H, C5H5), 3.14 (s, 4H,
2
CH2). 13C{1H} NMR (CD2Cl2, 62.90 MHz): δ 296.7 (t, J PC
)
18 Hz, Ru-C), 214.7 (Ru-CC), 162.3 (Ru-CCC), 144.1 (Ru-
CCCC), 141.8 (CH2CH2C), 135.3 (m, 1J PC ) 24 Hz, P-C), 133.3
2
(t, J PC ) 4 Hz, P-CC), 132.0 (CH), 130.8 (P-CCCC), 130.7
3
(CH), 128.7 (t, J PC ) 4 Hz, P-CCC), 127.3 (CH), 93.6 (C5H5),
35.1 (CH2). IR (KBr): ν(CCC) 1925 cm-1
. MS (FAB): m/z
(relative intensity) 907 (100) [M+], 645 (76.6) [(M - PPh3)+],
429 (98.2) [(CpRuPPh3)+]. UV/vis (CHCl3): λmax (ꢀ) 502
(21 880) nm (L mol-1 cm-1). UV/vis (CH3CN): λmax (ꢀ) 496
(20 360) nm (L mol-1 cm-1). Anal. Calcd for C58H47F6P3Ru
(Mr ) 1051.99): C, 66.22; H, 4.50. Found: C, 66.38; H, 4.81.
Syn th esis of 4. A mixture of CpRu(PPh3)2Cl (726 mg, 1
mmol) and 3 (170 mg, 1.5 mmol) was heated in refluxing
methanol (80 mL) for 30 min. The deep red solution was cooled,
and ca. 40 mg of sodium was added. 4 precipitated as a yellow
solid, which was isolated by filtration, washed with MeOH,
and dried in vacuo. Yield: 600 mg (75%). 1H NMR (CDCl3,
250 MHz): δ 7.50 (m, 12H, PCCCH), 7.20 (t, 6H PCCCCH),
7.09 (t, 12H, PCCH), 6.61 (m, 2H, CH), 6.04 (m, 2H, CH), 5.25
(m, 2H, CH), 4.24 (s, 5H, C5H5), 2.59 (m, 1H, CH). 13C{1H}
1
NMR (CD2Cl2, 62.90 MHz): δ 139.1 (m, J PC ) 21 Hz, P-C),
2
133.8 (t, J PC ) 5 Hz, P-CC), 130.4, 128.5 (CH), 128.2 (P-
CCCC), 127.0 (t, 3J PC ) 4 Hz, P-CCC), 122.5 (CH), 111.9 (Ru-
2
CC), 93.6 (t, J PC ) 23 Hz, Ru-C), 84.8 (C5H5), 35.7 (C7 C-1).
IR (KBr): ν(CtC) 2086 cm-1. MS (EI, 70 eV): m/z (relative
intensity) 806 (1.2) [M+], 544 (1.0) [(M - PPh3)+], 262 (100)
(41) Veith, M.; Ba¨rnighausen, H. Acta Crystallogr., Sect. B 1974,
30, 1806.

1424 Organometallics, Vol. 16, No. 7, 1997
Tamm et al.
decay was detected, and empirical absorption corrections
(DIFABS)43 were applied to the raw data. The space groups
were found to be P21/n, P1h, and P21/n for (1b)PF6, (1d )PF6‚CH2-
Cl2 and 4, respectively. All structures were solved by Patter-
son methods. The positional parameters for all non-hydrogen
atoms were refined by using first isotropic and later anisotropic
thermal parameters. Difference Fourier maps calculated at
this stage showed almost all hydrogen positions. However,
all hydrogen atoms were added to the structure models at
calculated positions [d(C-H) ) 0.95 Å]44 and are unrefined.
The isotropic temperature factors for hydrogens were fixed to
Q-switch Nd:YAG laser (Quantronix 5216). Solutions of
p-nitroaniline in acetonitrile were used as external reference
(â(CH3CN) ) 29.2 × 10-30 esu).47 The general experimental
setup is described in ref 33b.
Ack n ow led gm en t. This work was financially sup-
ported by the Deutsche Forschungsgemeinschaft (Ta
189/1-1,2,3) and the Fonds der Chemischen Industrie.
We thank Prof. Dr. F. E. Hahn for both his generous
support and his substantial contribution to the solution
and refinement of the X-ray crystal structures and I.
Bru¨dgam (FU Berlin) for X-ray data collection on (1b)-
PF6 and (1d )PF6‚CH2Cl2. The excellent technical as-
sistance of T. Pape is gratefully acknowledged. We are
indebted to Dr. M. Laidlaw and S. M. Kuebler (Oxford)
for helpful discussions.
-
be 1.3 times the Beq of the parent atom. The PF6 anion in
(1b)PF6 is disordered, and two positions were identified for
this anion. All calculations were carried out with the MolEN
package.45 ORTEP46 was used for all molecular drawings.
Hyp er Ra leigh sca tter in g. The experiments were per-
formed at a wavelength of 1064 nm with a mode-locked
Su p p or tin g In for m a tion Ava ila ble: Tables giving crys-
tal data and structure refinement details, positional and
thermal parameters, and bond distances and angles and
figures giving additional views of the structures of (1b)PF6,
(1d )PF6‚CH2Cl2, and 4 (30 pages). Ordering information is
given on any current masthead page.
(42) Neutral scattering factors were used: International Tables for
X-Ray Crystallography; Kynoch Press: Birmingham, England, 1974;
Vol. IV, Table 2.2B. Terms of anomalous dispersion from: International
Tables for X-Ray Crystallography; Kynoch Press: Birmingham, En-
gland, 1974; Vol. IV, Table 2.3.1.
(43) Walker, N.; Stewart, D. Acta Crystallogr., Sect. A 1983, 39, 158.
(44) Churchill, M. R. Inorg. Chem. 1972, 12, 1213.
(45) MolEN: Molecular Structure Solution Procedures. Program
Descriptions; Enraf-Nonius: Delft, 1990. Definition of residuals: R )
OM9610556
2
2
∑||Fo| - |Fc||/∑|Fo|, Rw ) [∑w||Fo| - |Fc|| /∑w|Fo| ]1/2, w ) 1/[σ(F)]2.
(46) J ohnson, C. K. ORTEP II; Report ORNL-5138; Oak Ridge
National Laboratory: Oak Ridge, TN, 1971.
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