Preparation and structure elucidation of novel organoruthenium amidinates bearing η4-diene ligands

Article abstract of DOI:10.1016/S0022-328X(01)01150-0

A series of novel ruthenium amidinate complexes bearing η⁴-cyclooctadiene (COD) or η⁴-norbornadiene (NBD) ligand was prepared, and their structures were elucidated by spectroscopy and crystallography. A disilver amidinate, Ag₂{μ₂,η-PhNC(H)=NPh}₂, was treated with either (η⁴-COD)Ru(MeCN)₂Cl₂ or (η⁴-NBD)Ru(pyridine)₂Cl₂ to form the corresponding bisamidinate complex, (η⁴-COD)Ru{η²-PhNC(H)=NPh}₂ (5a) or (η⁴-NBD)Ru{η²-PhNC(H)=NPh}₂ (5a′), respectively, in moderate to good yield. Alternatively, (η⁴-COD)Ru{η²-ⁱPrNC(Me)=N ⁱPr}₂ (5b) or (η⁴-NBD)Ru{η²-ⁱPrNC(Me)=N ⁱPr}₂ (5b′) was synthesized by reaction of [(η⁴-COD)RuCl₂]_n or (η⁴-NBD)Ru(pyridine)₂Cl₂ with Li{ⁱPrNC(Me)=NⁱPr}. Careful treatment of (η⁴-NBD)Ru(pyridine)₂Cl₂ with one equivalent of Li{ⁱPrNC(Me)=NⁱPr} resulted in the formation of a monoamidinate complex, (η⁴-NBD)Ru{η²-ⁱPrNC(Me)=N ⁱPr}(pyridine)Br (6) as a good precursor for a mixed amidinate complex, (η⁴-NBD)Ru{η²-ⁱPrNC(Me)=N ⁱPr}{η²-PhNC(H)=NPh} (5c′), which was obtained by the reaction of 6 with Ag₂{μ₂,η-PhNC(H)=NPh}₂. Crystal structures of these complexes revealed the octahedral arrangement of the ligands.

Full text of DOI:10.1016/S0022-328X(01)01150-0

Journal of Organometallic Chemistry 634 (2001) 167–176
www.elsevier.com/locate/jorganchem
Preparation and structure elucidation of novel organoruthenium
amidinates bearing h4-diene ligands
Taizo Hayashida a,b, Kazuma Miyazaki a, Yoshitaka Yamaguchi c,
Hideo Nagashima a,b,c,d,
*
a Graduate School of Engineering Sciences, Kyushu Uni6ersity, Kasuga, Fukuoka 816-8580, Japan
b CREST, Japan Science and Technology Corporation (JST), Kyushu Uni6ersity, Kasuga, Fukuoka 816-8580, Japan
c Department of Materials Chemistry, Faculty of Engineering, Yokohama National Uni6ersity, Yokohama, Kanagawa 240-8501, Japan
d Institute of Ad6anced Material Study, Kyushu Uni6ersity, Kasuga, Fukuoka 816-8580, Japan
Received 31 May 2001; received in revised form 16 July 2001; accepted 17 July 2001
Abstract
A series of novel ruthenium amidinate complexes bearing h4-cyclooctadiene (COD) or h4-norbornadiene (NBD) ligand was
prepared, and their structures were elucidated by spectroscopy and crystallography. A disilver amidinate, Ag2{m2,h-Ph-
NC(H)ꢀNPh}2, was treated with either (h4-COD)Ru(MeCN)2Cl2 or (h4-NBD)Ru(pyridine)2Cl2 to form the corresponding
bisamidinate complex, (h4-COD)Ru{h2-PhNC(H)ꢀNPh}2 (5a) or (h4-NBD)Ru{h2-PhNC(H)ꢀNPh}2 (5a%), respectively, in moder-
ate to good yield. Alternatively, (h4-COD)Ru{h2-iPrNC(Me)ꢀNiPr}2 (5b) or (h4-NBD)Ru{h2-iPrNC(Me)ꢀNiPr}2 (5b%) was
synthesized by reaction of [(h4-COD)RuCl2]n or (h4-NBD)Ru(pyridine)2Cl2 with Li{iPrNC(Me)ꢀNiPr}. Careful treatment of
(h4-NBD)Ru(pyridine)2Cl2 with one equivalent of Li{iPrNC(Me)ꢀNiPr} resulted in the formation of a monoamidinate complex,
(h4-NBD)Ru{h2-iPrNC(Me)ꢀNiPr}(pyridine)Br (6) as a good precursor for a mixed amidinate complex, (h4-NBD)Ru{h2-
iPrNC(Me)ꢀNiPr}{h2-PhNC(H)ꢀNPh} (5c%), which was obtained by the reaction of 6 with Ag2{m2,h-PhNC(H)ꢀNPh}2. Crystal
structures of these complexes revealed the octahedral arrangement of the ligands. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Ruthenium; Amidinate; Diene ligand
atom in the amidinate ligands bonds with a different
metal center. In this case, amidinates also act as a
4-electron donor ligand to dimetal dication, M22+ [4].
Although a wide variety of transition metal amidi-
nates has been reported, organoruthenium complexes
having amidinate ligands are surprisingly rare [4f,5]. We
have recently investigated the preparation and charac-
terization of several organoruthenium complexes bear-
ing amidinate ligands [6]. Half-sandwich ruthenium(II
or IV) complexes bearing an amidinate and an h5-
C5Me5 ligand, 1–3, were prepared and characterized
[6a,b]. Interestingly, the formal valence electrons of 1
are 16, and thus 1 is highly reactive with various
2-electron donor ligands to form 2 and with allylic
halides to form ruthenium(IV)–h3-allyl complexes, 3.
An unusual bonding mode of the amidinate ligand was
seen in the crystal structure of 1, in which p-electrons
on the amidinate ligand are likely to take part in
stabilizing the coordinatively unsaturated ruthenium
1. Introduction
Allyl and pseudo-allyl moieties such as carboxylates,
dithiocarbamates, and amidinates have been extensively
studied as auxiliary ligands for a variety of transition
metals [1]. In particular, amidinates are one of the
well-investigated ligands [2], especially for early transi-
tion metals; for example, some of them have lately been
investigated as a substitute of an h5-cyclopentadienyl
ligand for catalytically active metallocene compounds
for polyolefin syntheses [3]. As reviewed by Kilner and
Edelmann [2], amidinate ligands are in many cases
bound to a metal through two metalꢁnitrogen bonds,
donating four electrons to a cationic metal center [2].
Certain amidinates alternatively behave as bridging lig-
ands for dinuclear complexes, in which each nitrogen
* Corresponding author. Fax: +81-92-583-7819.
E-mail address: nagasima@cm.kyushu-u.ac.jp (H. Nagashima).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01150-0

168
T. Hayashida et al. / Journal of Organometallic Chemistry 634 (2001) 167–176
center; this p-donor character of the amidinate ligands
was also suggested by the crystal structure of (h5-
C5Me5)2Ru2{m2-iPrNC(Me)ꢀNiPr}Br [6c] and DFT cal-
culations of (h5-C5H5)Ru{h2-HNC(H)ꢀNH} [6d].
Complexes bearing a h6-arene (6-electron donor) ligand
such as 4 were also studied [6e].
novel organoruthenium amidinates by replacement of
the halide by other nucleophiles. As one example, syn-
thesis of a ‘mixed’ amidinate complex 5c% was achieved
by treatment of 6 with Ag2{m2,h-PhNC(H)ꢀNPh}2.
As an extension of these studies, we were interested
in the synthesis of novel organoruthenium amidinates
having a h4-diene ligand (4-electron donor) shown as 5
and 6 in Fig. 1. These complexes are analogs of (h4-di-
ene)Ru(L%)2 or (h4-diene)Ru(L%)(L)(X) (L=2-electron
donor ligand, L%=allyl or pseudo-allyl ligand, X=
halogen atom). Although syntheses of several (h4-di-
ene)Ru(L%)2 (L%=h3-allyl [7], h2-carboxylate [8], or
h2-dithiocarbamate [9]) are found in the literature,
complete structure elucidation by crystallography and
detailed NMR analyses have not been performed in
many cases. The only example of (h4-diene)Ru(L%)-
(L)(X) reported was a dimeric complex having a bridg-
ing halogen ligand, [(h4-COD)Ru(h3-allyl)X]2 (X=Cl
or Br) [7a]. This prompts us to elaborate the prepara-
tion, spectroscopy, and crystallographic determination
of novel organoruthenium amidinate complexes of
types 5 and 6, which are expected to contribute to
better understanding of not only the chemistry of (h4-
diene)Ru(L%)2 or (h4-diene)Ru(L%)(L)(X) but also that
of organoruthenium amidinates. In this paper, we re-
port the preparation and structure elucidation of (h4-
COD)Ru(h2-amidinate)2 (5) and (h4-NBD)Ru(h2-ami-
dinate)2 (5%) (COD=1,5-cyclooctadiene, NBD=2,5-
norbornadiene); and syntheses of these novel
organoruthenium amidinates by treatment of several
dihalogenoruthenium(II) precursors with the corre-
sponding lithium or silver amidinates. Interestingly,
careful treatment of (h4-NBD)Ru(pyridine)2Cl2 with
one equivalent of Li{iPrNC(Me)ꢀCNiPr} led to success-
ful preparation of a monoamidinate complex, (h4-
NBD)Ru{h2-iPrNC(Me)ꢀCNiPr}(pyridine)Br (6). This
complex is expected to be a good precursor for other
2. Results and discussion
2.1. Syntheses of bisamidinate complexes,
(p4-diene)Ru(p2-amidinate)2, 5a, 5b, 5a% and 5b%
It is known that Ru complexes, [(h4-COD)RuCl2]n
(7) and [(h4-NBD)RuCl2]n (8), where COD=1,5-cy-
clooctadiene and NBD=2,5-norbornadiene, are useful
precursors for a variety of Ru(II)–diene complexes.
Treatment of these compounds with two equivalents of
amidinate anions was expected to give the correspond-
ing (h4-diene)Ru(h2-amidinate)2, 5. However, com-
plexes 7 and 8 have polymeric structures and are hardly
soluble in common organic solvents; this sometimes
causes a serious decrease of the reactivity. In this
context, soluble monomeric Ru(II) complexes, (h4-
COD)Ru(MeCN)2Cl2 (9) and (h4-NBD)Ru(pyri-
dine)2Cl2 (10), were also examined as precursors for 5.
As the amidinate anion,
a
lithium amidinate,
Li{iPrNC(Me)ꢀNiPr} (11) was used [2]. A silver salt,
Ag2{m2,h-PhNC(H)ꢀNPh}2 (12) [10], having a unique
dinuclear structure was expected to be an effective
source for introduction of the amidinate moiety to
ruthenium.
Syntheses of 5a, 5b, 5a%, and 5b% by combination of
ruthenium precursors and amidinate reagents are sum-
marized in Scheme 1 and Table 1. In a typical example,
treatment of the soluble ruthenium precursor 9 with an
equimolar amount of the silver salt 12 in CH2Cl2 at
room temperature for 6 h resulted in the formation of
(h4-COD)Ru{h2-PhNC(H)ꢀNPh}2 (5a) as a yellow
solid in 65% yield. When the polymeric precursor 7 was
used as the starting material, treatment with the silver
salt 12 gave only a trace amount of 5a. Assignment of
5a was performed by 1H- and 13C-NMR, IR, mass
spectra, and elemental analysis, and supported by crys-
tallography as described later. No reaction took place
in the attempted synthesis of (h4-COD)Ru{h2-
iPrNC(Me)ꢀNiPr}2 (5b) by reaction of 9 with the
lithium salt 11; this is attributed to poor solubility of 9
in ether and THF, which are suitable solvents for the
reaction with 11. Interestingly, the polymeric precursor
7 reacted with 11 to give 5b in ꢀ20% yield. NMR
spectra of the reaction mixture revealed that a number
of byproducts were formed. Since uncoordinated COD
was also detected, it is likely that extensive decomposi-
tion of the reaction intermediates occurred by the liber-
ation of COD ligand. The yield of 5b was somewhat
improved when the reaction was carried out in the
presence of COD (20 equivalents to 7) as shown in
Fig. 1. Ruthenium amidinate complexes bearing h5-C5Me5, h6-arene,
or h4-diene ligands.

T. Hayashida et al. / Journal of Organometallic Chemistry 634 (2001) 167–176
169
Scheme 1.
Table 1
Synthesis of (h4-diene)Ru(h2-amidinate)2 (5)
Entry
Ru-precursor
Amidinate salt
Reaction conditions
Product
Yield (%)
Solvent
Temperature
Time (h)
1
2
3
4
9
9
7
7
12
11
12
11
11
12
11
12
11
CH2Cl2
THF
CH2Cl2
THF
THF
CH2Cl2
THF
Room temperature
Room temperature
Room temperature
Room temperature
Room temperature
60 °C
Room temperature
Reflux
Room temperature
6
5a
–
5a
5b
65
–
Trace
21
30
66
71
Trace
20
a
12
24
48
24
6
24
24
12
5 b
6 c
7
7
5b
10
10
8
5a%
5b%
5a%
5b%
8
9
CH2Cl2
THF
8
a Trace amount of unknown complexes was obtained.
b 20 equivalents of COD were added.
c No reaction occurred at room temperature.
2.2. Characterization of (p4-diene)Ru(p2-amidinate)2
entry 5. In contrast, the reaction of
7
with
Li{tBuNC(Ph)ꢀNtBu} gave many products, each struc-
ture of which could not be assigned by the NMR
spectra. This result indicates that the reaction is sensi-
tive to the steric bulkiness of the amidinate ligand,
which is supported by the molecular structures of 5a
and 5b described later. Similar results were obtained for
the synthesis of the NBD analogs. Treatment of the
soluble precursor 10 with the silver salt 12 in CH2Cl2 at
60 °C gave (h4-NBD)Ru{h2-PhNC(H)ꢀNPh}2 (5a%) in
66% yield. Since 10 is soluble in THF, the lithium salt
11 also reacted with 10 and afforded (h4-NBD)Ru{h2-
iPrNC(Me)ꢀNiPr}2 (5b%) in 71% yield. Although the
polymeric precursor 8 hardly reacted with the silver salt
12, it was converted to 5b% by treatment with the
lithium salt 11 (ꢀ20%). All of these results suggest that
successful preparation of (h4-diene)Ru(h2-amidinate)2
can be achieved by treatment of the soluble Ru(II)
precursors, 9 and 10, with the silver salt of amidinate,
12. Easily available polymeric precursors, 7 and 8, can
also be used as the starting material; in this case, the
lithium amidinate 11 is useful for the introduction of
the amidinate moiety.
The (h4-diene)Ru(h2-amidinate)2, 5a, 5b, 5a%, and 5b%,
are stable in air and moisture. No decomposition oc-
curred when these complexes was heated in C6D6 at
80 °C for 2–3 days. In NMR spectroscopy, these com-
plexes showed typical signals due to the coordinated
carbonꢀcarbon double bonds. For example, in the
1
NMR spectra of 5a H resonances seen as a doublet of
triplets (J=4.4 and 8.8 Hz) at l 3.34 and 4.48 ppm and
13C signals observed at l 82.5 and 88.9 ppm are
assignable to the HCꢀCH moiety in the COD ligand.
Compared with (h4-COD)Ru(h2-carboxylate)2 com-
plexes showing 13C resonances due to the HCꢀHC
moiety in the COD ligand at l 84.6 and 89.2 ppm [8a],
the 13C signals of 5a or 5b appeared at higher field; this
is attributed to the strong electron-donating ability of
the amidinate ligand. The 13C signals tended to appear
at higher field than those of other (h4-COD)Ru(h2-
chelate)2 complexes; for example, 13C signals of olefinic
carbons of (h4-COD)Ru(h2-quinolin-8-olate)2 [11c] or
(h4-COD)Ru{h4-N,N%-ethylenebis(2-pyrrolyl)iminato}
[11d] are observed at l 92.9 and 93.0 ppm or l 81.9–
93.3 ppm in CDCl3, respectively. Slightly higher field

170
T. Hayashida et al. / Journal of Organometallic Chemistry 634 (2001) 167–176
nated CꢀC bond in the diene ligand is located at the
trans position of one nitrogen atom in each amidinate
ligand. The ruthenium atom and the NꢁCꢀN moiety in
shift of these carbon signals of 5b than those of 5a may
suggest stronger electron-donating character of the h2-
iPrNC(Me)ꢀNiPr ligand than that of h2-PhNC(H)ꢀNPh
ligand. As described above, two independent reso-
nances due to the CHꢀCH moiety appeared in both 1H-
and 13C-NMR. Similarly, peaks due to two phenyl
groups in the h2-PhNC(H)ꢀNPh ligand in 5a appeared
independently. These results suggest the C2 symmetric
structure of 5a in the solution state, which is in good
accord with the crystal structure of 5a described below.
Similar spectral features were also seen in 5b, 5a%, and
5b%.
The molecular structures of 5a, 5b and 5a% deter-
mined by crystallography are in accord with the spec-
tral features described above. The ORTEP drawings are
shown in Fig. 2, and selected bond distances and angles
are summarized in Table 2. All of the complexes have
distorted octahedral structures, in which each coordi-
the amidinate ligand are in
a plane, and two
RuꢁNꢁCꢀN planes make an angle of 93–94°. There is
a C2 axis in the molecules; for example, in the case of
5a, the C2 axis contains the ruthenium atom, the middle
point of C1 and C5 and that of N1 and N4. Two of the
i
Ph or Pr groups are close to the COD or NBD ligands.
t
If the introduction of bulky substituents such as a Bu
i
moiety in place of the Pr group is considered, signifi-
cant steric hindrance between the amidinate ligand and
the diene moiety is expected, which may prevent the
reaction of tBu-substituted amidinates as described
above. The CꢀC bond distances of the COD ligand in
,
5a and 5b are 1.39–1.44 A, which are significantly
longer than those of (h4-COD)Ru(h2-chelate)2 (e.g. (h4-
4
COD)Ru(h2-maltolato)2 [11b]; 1.34 and 1.46 A, (h -
,
2
,
COD)Ru(h -quinolin-8-olate)2 [11c]; 1.37 and 1.39 A).
Average of CꢀC bond distances of the NBD ligand in
4
,
5a% is 1.39 A, which is almost the same as (h -
2
,
NBD)Ru(h -S2CNEt2)2 (1.39 A) [9], but slightly longer
than that of D-[(h4-NBD)Ru(h2-L-phenylalanine)2]
,
(1.38 A) [11a]. The longer CꢀC distances are attributed
to strong back donation from the ruthenium amidinate
moiety.
2.3. Preparation of a monoamidinate complex,
(p4-NBD)Ru{p2-iPrNC(Me)ꢀNiPr}(pyridine)Br (6)
As described above, (h4-diene)Ru(h2-amidinate)2, 5a,
5b, 5a% and 5b% were prepared by replacement of two
chlorine atoms of the Ru(II) precursors, 7–10, by the
amidinate ligands. Although the reactions should be
stepwise, there was only a small rate difference between
the first and second substitution reactions in many
cases, and an intermediate having only one amidinate
ligand was rarely obtained. One successful example
accomplished to date is preparation of (h4-
NBD)Ru{h2-iPrNC(Me)ꢀNiPr}(pyridine)Br (6), which
was obtained by careful treatment of monomeric pre-
cursor 10 with the lithium salt 11 in THF at room
temperature for 1 h as shown in Scheme 2. The initial
product of this reaction was (h4-NBD)Ru{h2-
iPrNC(Me)ꢀNiPr}(pyridine)Cl. Since the lithium salt 11
i
is synthesized in situ from PrNꢀCꢀiPr with MeLi con-
taining a substantial amount of LiBr, replacement of
the chlorine atom by bromine atom took place
smoothly to give 6 as a single product.
This monoamidinate complex 6 was isolated in 64%
yield as an orange solid, which was less stable to air or
moisture than the bisamidinate complexes. In fact, 6
gradually decomposed in solution even under an inert
gas atmosphere. H- and 13C-NMR spectra of 6 indi-
cated no symmetry of the molecule. These spectroscopic
data are consistent with the molecular structure of 6
1
Fig. 2. ORTEP drawings of the complexes 5a (top), 5b (middle), and
5a% (bottom) with thermal ellipsoids drawn at 50% probability level.
All hydrogen atoms are omitted for clarity.

T. Hayashida et al. / Journal of Organometallic Chemistry 634 (2001) 167–176
171
Table 2
,
Selected bond lengths (A) and bond angles (°) for 5a, 5b and 5a%
5a
5b
5a%
Bond lengths
Ru1ꢁN1
Ru1ꢁN2
Ru1ꢁN3
Ru1ꢁN4
Ru1ꢁC1
Ru1ꢁC2
Ru1ꢁC5
Ru1ꢁC6
C1ꢁC2
2.138(2)
2.163(2)
2.156(2)
2.141(3)
2.182(3)
2.172(3)
2.181(3)
2.169(3)
1.404(4)
1.388(5)
2.197(11)
2.179(9)
2.089(10)
2.092(11)
2.184(11)
2.194(8)
2.122(3)
2.149
2.151(3)
2.150(3)
2.160(3)
2.156(3)
2.162(3)
2.162(3)
1.387(5)
1.400(5)
RuꢁC1
RuꢁC2
RuꢁC6
RuꢁC7
C1ꢁC2
C6ꢁC7
2.156(9)
2.155(11)
1.416(15)
1.440(16)
C5ꢁC6
Bond angles
N1ꢁRu1ꢁN4
N2ꢁRu1ꢁN3
N1ꢁRu1ꢁN2
N3ꢁRu1ꢁN4
N1ꢁC21ꢁN2
N3ꢁC34ꢁN4
147.93(10)
92.48(9)
61.33(9)
60.9799)
112.8(2)
112.6(3)
143.68(10)
95.03(12)
60.9(4)
61.7(4)
117.0(10)
104.8(9)
147.11(11)
94.05(11)
61.37(10)
61.51(10)
111.8(3)
N1ꢁC12ꢁN12
N3ꢁC20ꢁN4
N1ꢁC14ꢁN2
N3ꢁC27ꢁN4
113.1(3)
determined by crystallography. The ORTEP drawing is
illustrated in Fig. 3, and selected bond distances and
angles are listed in the figure caption. Two CꢀC moi-
eties, two nitrogen atoms in the amidinate ligand, a
bromine atom, and a nitrogen atom in the pyridine
ligand are arranged octahedrally with RuꢁN and RuꢁC
,
distances of ca. 2.10 and 2.16 A, respectively.
The monoamidinate complex 6 has a RuꢁBr bond,
which is replaceable by other nucleophiles; this suggests
that 6 could be a unique starting complex for other
organoruthenium amidinates. In fact, treatment of 6
with the lithium amidinate 11 gave 5b% in 71% yield as
shown in Scheme 2. This suggests that 6 is an interme-
diate of the reaction from 10 to 5b%, and that the
reaction from 6 to 5b% is slower than the substitution
reaction of 10 to 6. A further interesting application of
this stepwise substitution is the successful preparation
Scheme 2.
of
a
mixed amidinate complex, (h4-NBD)Ru{h2-
iPrNC(Me)ꢀNiPr}{h2-PhNC(H)ꢀNPh} (5c%) by reaction
of 6 with the silver amidinate 12 as shown in Scheme 3.
3. Conclusions
We have described preparation of three types of
novel ruthenium amidinate complexes which have one
h4-diene ligand and either one or two amidinate lig-
ands. These complexes are a rare example of well-char-
acterized (h4-diene)Ru(L%)2 or (h4-diene)Ru(L%)(L)(X)
(L=2-electron donor ligand, L%=allyl or pseudo-allyl
ligand, X=halogen atom). This study contributes to a
better understanding of the chemistry of (h4-di-
Fig. 3. Molecular structure of 6. Anisotropic displacement parameters
are drawn at 50% probability level. All hydrogen atoms are omitted
,
for clarity. Representative bond distances (A) and angles (°) are as
follows: Ru1ꢁN1=2.093(7), Ru1ꢁN2=2.114(7), Ru1ꢁN3=2.176(7),
RuꢁBr=2.5803(12),
RuꢁC6=2.158(10),
RuꢁC3=2.151(9),
RuꢁC7=2.170(10),
RuꢁC4=2.172(10),
C3ꢁC4=1.400(15),
ene)Ru(pseudo-allyl)2
complexes
and
that
of
organoruthenium amidinates. Furthermore, as shown
C6ꢁC7=1.383(16), N1ꢁRu1ꢁN2=61.5(3), N1ꢁC14ꢁN2=109.2(7).

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T. Hayashida et al. / Journal of Organometallic Chemistry 634 (2001) 167–176
4.2. Preparation of (p4-COD)Ru{p2-PhNC(H)ꢀNPh}2
(5a)
In a Schlenk tube, (h4-COD)Ru(CH3CN)2Cl2 (380
mg, 1.05 mmol) and Ag2{m2,h-PhNC(H)ꢀNPh}2 (636
mg, 1.05 mmol) were dissolved in CH2Cl2 (20 ml) at
room temperature (r.t.), and the reaction mixture was
stirred for 6 h. After the precipitated silver salts were
removed by filtration through celite, the resulting solu-
tion was concentrated in the presence of celite (500 mg).
The crude products adsorbed to celite were placed on
the head of an alumina column (f 17×80 mm), and
eluted with a mixture of hexane and Et2O (10:1). The
desired product (5a) was obtained as an orange solid
(409 mg, 0.68 mmol, 65% yield). M.p.: 138 °C (dec.).
Scheme 3.
in the synthesis of mixed amidinate complex, 5c%, the
fact that (h4-diene)Ru(h2-amidinate)(L)Br (6) is an in-
teresting precursor for novel organoruthenium amidi-
nates by nucleophilic substitution of the bromide
suggests that this complex is an interesting starting
point for further organoruthenium chemistry. We are
currently concentrating on a search for new reactions of
these novel amidinate complexes.
1
TLC: Rf=0.40 (hexane:Et2O=10:1, Al2O3). H-NMR
(400 MHz, CDCl3): l 1.77–1.87 (m, 4H, CH2 of COD),
1.93–2.02 (m, 4H, CH2 of COD), 3.34 (dt, J=4.4, 8.8
Hz, 2H, olefinic protons of COD), 4.48 (dt, J=4.4, 8.8
Hz, 2H, olefinic protons of COD), 6.92–6.97, 6.99–
7.04, 7.09–7.18, 7.25–7.34 (m each, 20H in total, inte-
gral ratio=2:4:10:4, C6H5 of amidinates), 8.34 (s, 2H,
CH of amidinates). 13C{1H}-NMR (100 MHz, CDCl3):
l 29.56, 29.58 (CH2 of COD), 82.57, 89.23 (olefinic
carbons of COD), 120.75, 122.36, 122.58, 123.10,
128.79, 129.16, 147.92, 149.80 (C6H5 of amidinates),
157.50 (NCN of amidinates). EIMS: [M+]=600. Anal.
Calc. for C34H34N4Ru: C, 68.09; H, 5.71; N, 9.34.
Found: C, 68.12; H, 5.74; N, 9.33%.
4. Experimental
4.1. General procedure
Manipulation of air- and moisture-sensitive organo-
metallic compounds was carried out under a dry argon
atmosphere using standard Schlenk tube techniques
associated with a high-vacuum line. All solvents were
distilled over appropriate drying reagents prior to use
(THF, toluene, hexane; Ph2CO/Na, CH2Cl2; CaH2).
RuCl3 hydrate purchased from Furuya Metal Co. Ltd.
or Nacalai Tesque Inc. was used as received. A lithium
reagent, MeLi in Et2O (containing LiBr) was purchased
from Kanto Chemical Co. Inc. and titrated prior to
use. Other reagents employed in this research were used
without further purification. (h4-COD)Ru(CH3CN)2Cl2
[12], [(h4-COD)RuCl2]n [12], (h4-NBD)Ru(pyridine)2Cl2
[13], [(h4-NBD)RuCl2]n [14], Ag2{m2,h-PhNCHNPh}2
[10], and Li{iPrNC(Me)ꢀNiPr} [6a] were prepared as
described in the literature. Column chromatography
and thin layer chromatography were carried out using
Al2O3 (Merck aluminum oxide 90 standardized, and
Merck TLC aluminum sheets aluminum oxide 150 F254
neutral (type T), respectively).
4.3. Preparation of (p4-COD)Ru{p2-iPrNC(Me)ꢀ
NiPr}2 (5b)
In a Schlenk tube, [(h4-COD)RuCl2]n (170 mg, 0.61
mmol) and Li{iPrNC(Me)ꢀNiPr} (179 mg, 1.21 mmol)
were dissolved in THF (10 ml) at r.t., and the reaction
mixture was stirred for 48 h. After the solvent was
removed in vacuo, the residue was dissolved in hexane
(30 ml). The insoluble materials were filtered off
through celite, and the resulting solution was concen-
trated to two-thirds of its original volume. Brown
crystals were grown by cooling the solution at −30 °C
(62 mg, 0.13 mmol, 21% yield). M.p.: 151 °C (dec.).
1H-NMR (400 MHz, CDCl3): l 0.99 (d, J=6.6 Hz,
6H, CH(CH3)2 of amidinates), 1.04 (d, J=6.6 Hz, 6H,
CH(CH3)2 of amidinates), 1.40 (d, J=6.8 Hz, 6H,
CH(CH3)2 of amidinates), 1.46 (d, J=7.1 Hz, 6H,
CH(CH3)2 of amidinates), 1.85 (s, 6H; CCH3 of amidi-
nates), 1.80–1.91 (m, 2H, CH2 of COD), 2.15–2.29 (m,
4H, CH2 of COD), 2.32–2.46 (m, 2H, CH2 of COD),
2.63–2.74 (m, 2H, olefinic protons of COD), 3.59 (sep,
J=6.6 Hz, 2H, CH(CH3)2 of amidinates), 3.51–3.65
(m, 2H, olefinic protons of COD), 3.78 (sep, J=6.8 Hz,
2H, CH(CH3)2 of amidinates). 13C{1H}-NMR (100
MHz, CDCl3): l 17.44 (CCH3 of amidinates), 24.51,
24.63, 24.77, 25.23 (CH(CH3)2 of amidinates), 29.84,
1H and 13C spectra were recorded on JEOL Lambda
600 and Lambda 400 spectrometers at ambient temper-
ature. H- and 13C-NMR chemical shifts (l values) are
1
given in ppm relative to solvent resonances. All cou-
pling constants were reported in Hertz. IR spectra were
recorded on a JASCO FT/IR-550 spectrometer. Melt-
ing points were measured on a Yanaco micro melting
point apparatus. EIMS and HRMS spectra were
recorded on a JEOL Mstation JMS-70 apparatus. Ele-
mental analyses were performed at the Elemental Anal-
ysis Center, Faculty of Science, Kyushu University.

T. Hayashida et al. / Journal of Organometallic Chemistry 634 (2001) 167–176
173
32.85 (CH2 of COD), 47.80, 49.26 (CH(CH3)2 of amid-
inates), 81.18, 82.88 (olefinic carbons of COD), 166.24
(NCN of amidinates). EIMS: [M+]=492. Anal. Calc.
for C24H46N4Ru: C, 58.62; H, 9.43; N, 11.39. Found: C,
58.67; H, 9.36; N, 11.21%.
nates), 1.52 (d, J=6.8 Hz, 6H, CH(CH3)2 of amidi-
nates), 1.82 (s, 6H, CCH3 of amidinates), 3.10–3.17 (m,
2H, olefinic protons of NBD), 3.51 (sep, J=6.5 Hz,
2H, CH(CH3)2 of amidinates), 3.52–3.58 (m, 2H, CH
of NBD), 3.75–3.82 (m, 2H, olefinic protons of NBD),
3.93 (sep, J=6.8 Hz, 2H, CH(CH3)2 of amidinates).
13C{1H}-NMR (100 MHz, CDCl3): l 15.33 (CCH3 of
amidinates), 23.80, 24.48, 25.10, 25.57 (CH(CH3)2 of
amidinates), 47.70, 50.96 (CH(CH3)2 of amidinates),
50.37 (CH of NBD), 56.41 (CH2 of NBD), 60.22, 60.32
(olefinic carbons of NBD), 164.33 (NCN of amidi-
nates). EIMS: [M+]=476. HRMS: Anal. Calc. for
C23H42N4Ru: 476.2453. Found: 476.2456.
The reaction for 6 to 5b%: In a Schlenk tube, 6 (140
mg, 0.28 mmol) was treated with Li{iPrNC(Me)ꢀNiPr}
(141 mg, 0.60 mmol) in THF (10 ml) at r.t. for 15 h.
The solvent was removed in vacuo and the residue was
adsorbed to celite (150 mg). This adsorbed material was
moved to the head of an alumina column (f 17×40
mm) and eluted with a mixture of hexane and Et2O
(10:1). The desired product (94 mg, 0.20 mmol) was
obtained in 71% yield as a yellow solid.
4.4. Preparation of (p4-NBD)Ru{p2-PhNC(H)ꢀNPh}2
(5a%)
In a Schlenk tube, a mixture of (h4-NBD)Ru(pyri-
dine)2Cl2 (101 mg, 0.24 mmol) and Ag2{m2,h-Ph-
NC(H)ꢀNPh}2 (140 mg, 0.231 mmol) dissolved in
CH2Cl2 (10 ml) was heated under reflux for 6 h. After
removal of the silver salts formed by filtration through
celite, the solution was concentrated. Chromatographic
purification (Al2O3, f 17×40 mm, eluents; hex-
ane:Et2O=10:1) of the residue adsorbed to celite (200
mg) afforded 5a% as a yellow solid (91 mg, 0.16 mmol,
66% yield). Recrystallization from CH2Cl2–hexane
gave a red crystal of 5a%. M.p.: 181 °C (dec.). TLC:
Rf=0.30 (hexane:Et2O=10:1, Al2O3). 1H-NMR (400
MHz, CDCl3): l 1.23 (t, J=1.3 Hz, 2H, CH2 of NBD),
3.36–3.41 (m, 2H, CH of NBD), 3.69–3.75 (m, 2H,
olefinic protons of NBD), 4.43–4.48 (m, 2H, olefinic
protons of NBD), 6.89 (tt, J=1.0, 7.5 Hz, 2H, C6H5 of
amidinates), 6.97 (dd, J=7.5, 8.3 Hz, 4H, C6H5 of
amidinates), 7.09 (dd, J=1.0, 8.3 Hz, 4H, C6H5 of
amidinates), 7.18 (tt, J=7.5, 8.4 Hz, 2H, C6H5 of
amidinates), 7.26 (dd, J=7.5, 8.4 Hz, 4H, C6H5 of
amidinates), 7.38 (dd, J=1.0, 8.5 Hz, 4H, C6H5 of
amidinates), 8.41 (s, 2H, CH of amidinates). 13C{1H}-
NMR (100 MHz, CDCl3): l 49.09 (CH of NBD), 56.49
(CH2 of NBD) 64.28, 65.18 (olefinic carbons of NBD)
118.22, 120.96, 121.34, 122.0, 127.73, 128.23, 146.35,
149.05 (C6H5 of amidinates), 154.46 (NCN of amidi-
nates). EIMS: [M+]=584. Anal. Calc. for
C33H30N4Ru: C, 67.91; H, 5.18; N, 9.60. Found: C,
68.03; H, 5.22; N, 9.57%.
4.6. Preparation of (p4-NBD)Ru{p2-iPrNC(Me)ꢀ
NiPr}(pyridine)Br (6)
In a Schlenk tube, (h4-NBD)Ru(pyridine)2Cl2 (213
mg, 0.50 mmol) was treated with Li{iPrNC(Me)ꢀNiPr}
(118 mg, 0.50 mmol) in THF (10 ml) at r.t. for 1 h.
After the removal of the solvent, the residue was ad-
sorbed to celite (300 mg). The adsorbed material was
moved to the head of an alumina column (f 17×40
mm) and eluted with a mixture of hexane and Et2O
(1:2). An orange band available was concentrated in
vacuo to give 6 in 64% yield (158 mg, 0.32 mmol).
Brown crystals were obtained by recrystallization of 6
from a mixture of toluene and hexane at −30 °C.
M.p.: 85 °C (dec.). TLC: Rf=0.38 (hexane:Et2O=1:2,
1
Al2O3). H-NMR (600 MHz, CDCl3): l 0.92 (d, J=6.8
4.5. Preparation of (p4-NBD)Ru{p2-iPrNC(Me)ꢀ
NiPr}2 (5b%)
Hz, 3H, CH(CH3)2 of amidinate), 0.96 (d, J=6.8 Hz,
3H, CH(CH3)2 of amidinate), 1.02 (d, J=6.8 Hz, 3H,
CH(CH3)2 of amidinate), 1.32 (d, J=6.8 Hz, 3H,
CH(CH3)2 of amidinate), 1.43 (dt, J=1.6, 8.2 Hz, 1H,
a proton due to the CH2 group of NBD), 1.46 (dt,
J=1.6, 8.2 Hz, 1H, a proton due to the CH2 group of
NBD), 1.90 (s, 3H, CCH3 of amidinate), 3.54 (sep,
J=6.8 Hz, 1H, CH(CH3)2), 3.57–3.66 (m, 2H,
CH(CH3)2 of amidinate and an olefinic proton of
NBD), 3.74 (t, J=3.9 Hz, 1H, an olefinic proton of
NBD), 3.78–3.83 (m, 1H, CH of NBD), 3.87–3.91 (m,
1H, CH of NBD), 4.08 (t, J=3.9 Hz, 1H, an olefinic
proton of NBD), 4.78 (t, J=3.9 Hz, 1H, an olefinic
proton of NBD), 7.22 (ddd, J=1.6, 6.6, 7.5 Hz, 2H,
C5H5N), 7.65 (tt, J=1.6, 7.5 Hz, 1H, C5H5N), 8.21
(dd, J=1.6, 6.6 Hz, 2H, C5H5N). 13C{1H}-NMR (150
MHz, CDCl3): l 15.47 (CCH3 of amidinate), 24.20,
In a Schlenk tube, (h4-NBD)Ru(pyridine)2Cl2 (180
mg, 0.43 mmol) was treated with Li{iPrNC(Me)ꢀNiPr}
(201 mg, 0.86 mmol) in THF (10 ml) at r.t. for 24 h.
The solvent was removed in vacuo and the residue was
adsorbed to celite (350 mg). This adsorbed material was
moved to the head of an alumina column (f 17×40
mm) and eluted with a mixture of hexane and Et2O
(10:1). The desired product (145 mg, 0.30 mmol) was
obtained in 71% yield as a yellow solid. M.p.: 95 °C
1
(dec.). TLC: Rf=0.35 (hexane:Et2O=10:1 Al2O3). H-
NMR (400 MHz, CDCl3): l 0.73 (d, J=6.5 Hz, 6H,
CH(CH3)2 of amidinates), 0.99 (d, J=6.5 Hz, 6H,
CH(CH3)2 of amidinates), 1.23 (t, J=1.6 Hz, 2H, CH2
of NBD), 1.48 (d, J=6.8 Hz, 6H, CH(CH3)2 of amidi-

174
T. Hayashida et al. / Journal of Organometallic Chemistry 634 (2001) 167–176
Table 3
Crystal data and structure refinement parameters for 5a, 5b, 5a%, and 6
5a
5b
5a%
6
Empirical formula
Formula weight
Temperature (K)
Crystal habits, color
Space group
C
599.74
293(2)
Prismatic, brown
P21/n
34H34N4Ru
C24H46N4Ru
491.72
273(2)
Prismatic, yellow
Cc
C33H30N4Ru
583.68
293(2)
C20H30BrN3Ru
493.45
293(2)
Prismatic, brown
P212121
Prismatic, brown
(
P1
Unit cell dimensions
,
a (A)
1.6209(11)
14.7695(13)
16.8303(11)
12.426(3)
15.357(19)
12.823(3)
10.6353(4)
12.5532(9)
10.4641(5)
96.1670(10)
99.770(2)
106353(4)
9.5779(12)
22.936(3)
,
b (A)
,
c (A)
h (°)
i (°)
101.720(4)
93.177(19)
k (°)
79.361(2)
1348.92(13)
2
1.437
0.610
3
,
V (A )
2828.4(4)
4
1.404
0.584
2443(9)
4
1.326
0.658
2076.7(5)
4
1.578
2.686
Z
Dcalc (g cm−3
)
Absorption coefficient (mm−1
F(000)
)
1232
1032
600
1000
Crystal size (mm)
q range for data collection (°)
Index ranges
0.20×0.20×0.50
2.37–27.48
05h515, 05k519,
−215l521
6265
0.15×0.20×0.30
2.59–27.50
05h516, 05k519,
−165l516
2929
0.20×0.30×0.30
1.66–27.48
05h513, −155k516,
−135l513
6129
0.20×0.30×0.30
1.78–27.48
05h512, 05k512,
05l529
Reflection collected
2681
Reflections observed (\2|)
Independent reflections
Data/restraints/parameters
R indices [I\2|(I)]
4866
2706
5291
2284
6265 [Rint=0.0000]
6265/0/352
R1=0.0507,
wR2=0.1349
R1=0.0630,
wR2=0.1473
1.048
2928 [Rint=0.8602]
2928/2/262
R1=0.0224,
wR2=0.0626
R1=0.0272,
wR2=0.0646
1.105
6129 [Rint=0.0000]
6129/0/343
R1=0.0385, wR2=0.1120
2681 [Rint=0.0000]
2681/0/226
R1=0.0552,
wR2=0.1547
R1=0.0650,
wR2=0.1642
1.212
R indices (all data)
R1=0.0506, wR2=0.1264
Goodness-of-fit on F2
1.012
Largest difference peak and hole 0.542 and −1.703
0.661 and −1.480
0.488 and −1.145
0.743 and −1.049
−3
,
(e A
)
24.69, 24.70, 25.3 (CH(CH3)2 of amidinate), 49.86 (CH
of NBD), 50.17, 50.36 (CH(CH3)2 of amidinate), 51.80
(CH of NBD), 58.27 (CH2 of NBD), 60.66, 64.59,
66.98, 68.47 (olefinic carbons of NBD), 124.03, 136.59,
150.86 (C5H5N) 167.05 (NCN of amidinate). EIMS:
[M+]=493. Anal. Calc. for C20H30N3BrRu: C, 48.68;
H, 6.13; N, 8.52. Found: C, 48.82; H, 5.81; N, 8.43%.
(400 MHz, CDCl3): l 0.84 (d, J=6.4 Hz, 3H,
CH(CH3)2 of amidinate), 0.96 (d, J=6.4 Hz, 3H,
CH(CH3)2 of amidinate), 1.22 (dt, J=1.5, 8.2 Hz, 1H,
a proton due to the CH2 of NBD), 1.31 (dt, J=1.5, 8.2
Hz, 1H, a proton due to the CH2 of NBD), 1.40 (d,
J=6.8 Hz, 3H, CH(CH3)2 of amidinate), 1.44 (d, J=
6.8 Hz, 3H, CH(CH3)2 of amidinate), 1.84 (s, 3H,
CCH3 of amidinate), 3.27–3.31 (m, 1H, CH of NBD),
3.33 (t, J=3.9 Hz, 1H, an olefinic proton of NBD),
3.53 (t, J=3.9 Hz, 1H, an olefinic proton of NBD),
3.53 (sep, J=6.4 Hz, 1H, CH(CH3)2 of amidinate),
3.88–3.93 (m, 1H, CH of NBD), 4.02 (sep, J=6.8 Hz,
1H, CH(CH3)2 of amidinate), 4.18 (t, J=3.9 Hz, 1H,
an olefinic proton of NBD), 4.20 (t, J=3.9 Hz, 1H, an
olefinic proton of NBD), 6.90–6.99, 7.04–7.11, 7.15–
7.22, 7.30–7.40 (m each, 10H in total, integral ratio=
3:1:2:4; C6H5 of amidinate), 8.29 (s, 1H, CH of
amidinate). 13C{1H}-NMR (100 MHz, CDCl3): l 14.69
(CCH3 of amidinate), 24.76, 24.81, 24.82, 25.72
(CH(CH3)2 of amidinate), 48.06 (CH(CH3)2 of amidi-
nate), 50.31 (CH of NBD), 50.74 (CH(CH3)2 of amidi-
nate), 51.15 (CH of NBD), 57.14 (CH2 of NBD), 59.03,
61.87, 63.80, 68.42 (olefinic carbons of NBD), 120.69,
4.7. Preparation of (p4-NBD)Ru{p2-PhNC(H)ꢀNPh}-
{p2-NiPrC(Me)ꢀNiPr} (5c%)
In a Schlenk tube, a mixture of 6 (75 mg, 0.15 mmol)
and Ag2{m2,h-PhNC(H)ꢀNPh}2 (46 mg, 0.075 mmol)
was dissolved in CH2Cl2 (10 ml) at r.t., and the reaction
mixture was heated under reflux for 2 h. After removal
of the formed silver salts by filtration through celite, the
residue was adsorbed to celite (170 mg) and the ad-
sorbed material was moved to the head of an alumina
column (f 17×40 mm). By eluting with a mixture of
hexane and Et2O (10:1), a yellow band was available,
the concentration of which gave 5c% as a yellow solid
(32 mg, 0.06 mmol, 40% yield). M.p.: 145 °C (dec.).
1
TLC: Rf=0.30 (hexane:Et2O=10:1, Al2O3). H-NMR

T. Hayashida et al. / Journal of Organometallic Chemistry 634 (2001) 167–176
175
(b) R. Go´mez, M.L.H. Green, J.L. Haggitt, J. Chem. Soc. Chem.
Commun. (1994) 2607;
121.28, 121.60, 121.78, 128.39, 129.03, 148.71, 151.27
(C6H5 of amidinate), 154.72 (NC(H)N of amidinate),
166.84 (NC(CH3)N of amidinate). EIMS: [M+]=530.
HRMS: Anal. Calc. for C28H36N4Ru: 530.1983. Found:
530.1988.
(c) R. Go´mez, R. Duchateau, A.N. Chernega, J.H. Teuben, F.T.
Edelman, M.L.H. Green, J. Organomet. Chem. 491 (1995) 153;
(d) L.R. Sita, J.R. Babcock, Organometallics 17 (1998) 5228;
(e) L.A. Koterwas, J.C. Fettinger, L.R. Sita, Organometallics 18
(1999) 4183;
(f) J.R. Babcock, C. Incarvito, A.L. Rheingold, J.C. Fettinger,
L.R. Sita, Organometallics 18 (1999) 5729;
4.8. X-ray determination of 5a, 5b, 5a% and 6
(g) K.C. Jayaratne, R.J. Keaton, D.A. Henningsen, L.R. Sita, J.
Am. Chem. Soc. 122 (2000) 10490;
(h) J. Richter, F.T. Edelmann, M. Noltemeyer, H.-G. Schmidt,
M. Shmulinson, M.S. Eisen, J. Mol. Catal. A: Chem. 130 (1998)
149;
(i) V. Volkis, M. Shmulinson, C. Averbuj, A. Lisovskii, F.T.
Edelmann, M.S. Eisen, Organometallics 17 (1998) 3155;
(j) C. Averbuj, E. Tish, M.S. Eisen, J. Am. Chem. Soc. 120
(1998) 8640;
(k) C. Averbuj, M.S. Eisen, J. Am. Chem. Soc. 121 (1999) 8755;
(l) D.Y. Dawson, J. Arnold, Organometallics 16 (1997) 1111;
(m) J.R. Hagadorn, J. Arnold, Angew. Chem. Int. Ed. 37 (1998)
1729;
Crystallographic details are listed in Table 3. Single
crystals for X-ray diffraction were grown from a hot
CH3CN solution at r.t. for 5a, from a solution of
toluene–n-hexane at −30 °C for 5b, from a concen-
trated CH2Cl2 solution at r.t. for 5a%, and from a
solution of toluene–n-hexane at r.t. for 6. Diffraction
data for 5a, 5a%, and 6 were collected on a Rigaku
R-AXIS RAPID IP diffractometer (Mo–Ka, u=
,
0.71069 A) and then processed with TEXSAN [15]; for 5b
they were collected on a Rigaku AFC-7R four-circle
,
diffractometer (Mo–Ka, u=0.71069 A) using ꢀ–2q
(n) J.R. Hagadorn, J. Arnold, Organometallics 17 (1998) 1355;
(o) J.M. Decker, S.J. Geib, T.Y. Meyer, Organometallics 18
(1999) 4417.
scan technique. Structure solutions were performed by
direct methods (5b, 5a% and 6) with the program SIR-92
[16] and the Patterson method (5a) with the program
DIRDIF-94-PATTY [17]. Refinements were carried out by
full-matrix least-squares on F2 with all non-hydrogen
atoms refined anisotropically using the program
SHELXL-97-2 PC version [18]. The positions of all hy-
drogen atoms were calculated assuming idealized
geometries.
[4] (a) F.A. Cotton, L.M. Daniels, D.J. Maloney, J.H. Matonic,
C.A. Murillo, Polyhedron 13 (1994) 815;
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Inorg. Chim. Acta 242 (1996) 31;
(c) F.A. Cotton, L.M. Daniels, J.H. Matonic, C.A. Murillo,
Inorg. Chim. Acta 256 (1997) 277;
(d) F.A. Cotton, L.M. Daniels, D.J. Maloney, J.H. Matonic,
C.A. Murillo, Inorg. Chim. Acta 256 (1997) 283;
(e) F.A. Cotton, G.T. Jordan IV, C.A. Murillo, J. Su, Polyhe-
dron 16 (1997) 1831;
(f) J.L. Bear, B. Han, S. Huang, J. Am. Chem. Soc. 115 (1993)
1175;
5. Supplementary material
(g) A. Singhal, V.K. Jain, M. Nethaji, A.G. Samuelson, D.
Jayaprakash, R.J. Butcher, Polyhedron 17 (1998) 3531.
[5] (a) S.D. Robinson, A. Sahajpal, J. Organomet. Chem. 117 (1976)
C111;
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 164059, 164057, 164058 and
164060 for compounds 5a, 5b, 5a% and 6, respectively.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (Fax: +44-1223-336033;
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
(b) L.D. Brown, S.D. Robinson, A. Sahajpal, J.A. Ibers, Inorg.
Chem. 16 (1977) 2728;
(c) A.D. Harris, S.D. Robinson, A. Sahajpal, M.B. Hursthouse,
J. Chem. Soc. Dalton Trans. (1981) 1327.
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