Syntheses, structures, and spectroscopic properties of cis,cis- and trans, cis-[Ru(I)(Me)(CO)2(α-diimine)] complexes

Article abstract of DOI:10.1002/(SICI)1099-0682(199809)1998:9<1243::AID-EJIC1243>3.0.CO;2-J

The syntheses, structures, and spectroscopic properties are reported for trans,cis and cis,cis isomers of [Ru(I)(Me)(CO)₂(α-diimine)] [α-diimine = N,N′-diisopropyl1,4-diazabutadiene (iPr-DAB), pyridine-2-carbaldehyde N-isopropylimine (iPr-PyCa), 4,4′-dimethyl-2,2′-bipyridine (dmb)] which differ in their photochemical behaviour. The structures of trans,cis- and cis,cis-[Ru(I)(Me)(CO)₂(iPr-DAB)] have been determined by a single-crystal X-ray diffraction study. The crystals of both isomers are monoclinic and belong to the same P2₁/n space group with Z = 4. Refinement converged to R = 0.043 for the trans,cis isomer and to R = 0.065 for the cis,cis isomer. Both complexes have a distorted octahedral geometry, in the cis,cis isomer the methyl ligand is located in an equatorial, the iodide in an axial position. According to the ¹H- and ¹³C-NMR and resonance Raman spectra the imine groups of the iPr-DAB ligand are inequivalent in the cis,cis isomer. The absorption spectra vary with the α-diimine, not so much with the isomeric structure of the complex. Both isomers possess two visible absorption bands, which, according to the resonance Raman spectra, belong to charge transfer transitions from mixed metal-halide orbitals to the α-diimine. The resonance Raman spectra show that this charge transfer excitation is accompanied, for both isomers, with an angular distortion of the methyl ligand. These spectral data show that the difference in photochemical behaviour of the two isomers is not due to a change in the excited state character.

Full text of DOI:10.1002/(SICI)1099-0682(199809)1998:9<1243::AID-EJIC1243>3.0.CO;2-J

FULL PAPER
Syntheses, Structures, and Spectroscopic Properties of cis,cis- and
trans,cis-[Ru(I)(Me)(CO)2(␣-diimine)] Complexes
Cornelis J. Kleverlaana, Derk J. Stufkens*a, Jan Fraanjeb, and Kees Goubitzb
Anorganisch Chemisch Laboratorium, Institute of Molecular Chemistry, Universiteit van Amsterdama,
Nieuwe Achtergracht 166, NL-1018 WV Amsterdam, The Netherlands
Laboratorium voor Kristallografie, Institute of Molecular Chemistry, Unmiversiteit van Amsterdamb,
Nieuwe Achtergracht 166, NL-1018 WV Amsterdam, The Netherlands
Received March 20, 1998
Keywords: Ruthenium / α-Diimine ligand / Carbonylmetal compounds / Isomers /X-ray structure / Resonance Raman
spectra
The syntheses, structures, and spectroscopic properties are According to the 1H- and 13C-NMR and resonance Raman
reported
for
trans,cis
and
cis,cis
isomers
of
spectra the imine groups of the iPr-DAB ligand are
[Ru(I)(Me)(CO)2(α-diimine)] [α-diimine = N,NЈ-diisopropyl- inequivalent in the cis,cis isomer. The absorption spectra
1,4-diazabutadiene (iPr-DAB), pyridine-2-carbaldehyde N-
isopropylimine (iPr-PyCa), 4,4Ј-dimethyl-2,2Ј-bipyridine
(dmb)] which differ in their photochemical behaviour. The
vary with the α-diimine, not so much with the isomeric
structure of the complex. Both isomers possess two visible
absorption bands, which, according to the resonance Raman
structures of trans,cis- and cis,cis-[Ru(I)(Me)(CO)2(iPr-DAB)] spectra, belong to charge transfer transitions from mixed
have been determined by a single-crystal X-ray diffraction
study. The crystals of both isomers are monoclinic and belong
metal-halide orbitals to the α-diimine. The resonance Raman
spectra show that this charge transfer excitation is
to the same P21/n space group with Z = 4. Refinement accompanied, for both isomers, with an angular distortion of
converged to R = 0.043 for the trans,cis isomer and to R = the methyl ligand. These spectral data show that the
0.065 for the cis,cis isomer. Both complexes have a distorted
octahedral geometry, in the cis,cis isomer the methyl ligand
is located in an equatorial, the iodide in an axial position.
difference in photochemical behaviour of the two isomers is
not due to a change in the excited state character.
3
Introduction
occur from a reactive σπ* state in which σ represents the
high-lying σ-bonding orbital, and π* the lowest unoccupied
orbital of the α-diimine ligand. Nearly all metalϪmetal-
bonded complexes show at room temperature an efficient
homolysis reaction, whereas the reactivity of the metalϪal-
kyl complexes strongly depends on the nature of the alkyl
group. For instance, the complexes [Re(R)(CO)3(α-diimine)]
(R ϭ Et, Bzl) photodecompose into radicals with high
quantum yield (Φ > 0.8), whereas the quantum yield is only
0.05 for the corresponding [Re(Me)(CO)3(iPr-DAB)] com-
plex.[27] Similarly, in the case of [Ru(X)(R)(CO)2(iPr-DAB)]
(X ϭ halide; R ϭ Me, Et, iPr, Bzl), the isopropyl and benzyl
complexes show a high efficiency for their homolysis reac-
tion, whereas the methyl and ethyl complexes do not un-
dergo such a reaction.[32] A preliminary study showed that
the complex trans,cis-[Ru(I)(Me)(CO)2(dmb)] does not un-
dergo a homolysis reaction, but is yet photolabile. It photo-
isomerises from its thermally stable trans(I,Me),cis(CO,CO)
conformation into one of the two cis,cis isomeric forms.
This photoproduct is photostable but thermally regenerates
the parent trans,cis complex. In order to understand this
remarkable behaviour, we have undertaken a structural and
spectroscopic study of the trans,cis and cis,cis isomers. The
results of this study are presented in this article.
Many transition metal complexes having a lowest metal-
to-ligand charge transfer (MLCT) excited state undergo ef-
ficient energy and electron transfer processes. Best studied
in this respect are the complexes [Ru(bpy)3]2ϩ[1][2][3] and
[Re(LЈ)(CO)3(bpy)]nϩ (n ϭ 0, 1; bpy ϭ 2,2Ј-bipyridine;
LЈ ϭ halide, O- or N-donor ligand)[4][5][6][7][8], and their
derivatives. The [Re(LЈ)(CO)3(α-diimine)]nϩ complexes have
the special property that variation of LЈ not only influences
the energy and character of the lowest excited state but may
also change its reactivity. For instance, the metalϪmetal-
bonded complexes [(LnM)Re(CO)3(α-diimine) [LnM ϭ
(CO)5Mn, (CO)5Re, (CO)4Co, Cp(CO)2Fe] show a homo-
lytic splitting of the ReϪmetal bond on irradiation with
visible light.[4][9][10][11][12][13][14][14][15][16][17][18][19][20][21][22][23]
Such homolysis reactions have also been observed for the
Mn complexes [(CO)5MnϪMn(CO)3(α-diimine)][13][18] and
the Ru compounds [(LnM)Ru(Me)(CO)2(α-diimine)]
[LnM
ϭ
(CO)5Mn, (CO)5Re, (CO)4Co][24][25] and
[Ru(SnPh3)2(CO)2(α-diimine).[25][26] Similar photoreactions
occur for the metalϪalkyl (R) complexes [M(R)(CO)3(α-di-
imine)] (M ϭ Mn, Re)[27][28][29][30][31], [Ru(X)(R)(CO)2(α-
diimine)] (X ϭ halide)[31][32], [Ir(R)(CO)(PAr3)2(mnt)][33]
,
[Pt(Me)4(α-diimine)][34], and [Zn(R)2(α-diimine)][35], and
even for the metalϪhalide complexes mer-[Mn(X)(CO)3(α-
The syntheses and molecular structures of several of
diimine)].[36][37] These homolysis reactions are assumed to these complexes have been first described by tom Dieck and
Eur. J. Inorg. Chem. 1998, 1243Ϫ1251
WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1998
1434Ϫ1948/98/0909Ϫ1243 $ 17.50ϩ.50/0
1243

C. J. Kleverlaan, D. J. Stufkens, J. Fraanje, K. Goubitz
FULL PAPER
co-workers[38][39], while the complexes have been used for
The iPr-DAB ligand is σ(N1)Ϫσ(N2)-bonded to the ru-
an acylation reaction by Vrieze and co-workers.[40][41] The thenium centre, just as in the case of [Ru(Me)(CO)2(iPr-
related complexes [Ru(Cl)2(CO)2(α-diimine)] are known to DAB)]ϩOTfϪ[43], [Ru(I){C(O)Me}(CO)2(iPr-DAB)][43] and
form selectively stereoisomers.[42] It will be shown that in [Ru(I)(Me)(iPr-DAB)(nbd)].[44] The bite angle of 76.8(2)°,
the case of the complexes under study only one of the pos- which causes the deviation from a regular octahedral struc-
sible four stereoisomers presented in Figure 1 [structure IIb] ture, has also been found for these complexes. The RuϪMe
˚
is formed.
bond length [2.183(9) A] is comparable with those of the
RuϪC bonds in the complexes [Ru(Me)(CO)2(iPr-
Figure 1. General molecular structures of the different isomers of
[Ru(I)(Me)(CO)2(α-diimine)] and of the α-diimine ligands used
DAB)]ϩOTfϪ [2.122(9) A][43], [Ru(Me)(Mn(CO)5)(CO)2-
˚
[45]
˚
(iPr-PyCa)] [2.148(5) A]
, [Ru(Me)(CO)2(iPr-DAB)]2
[39]
˚
[2.152(5) A]
and [Ru(I)(Me)(iPr-DAB)(nbd)] [2.222(13)
[44]
˚
˚
A].
The RuϪI bond length [2.7998(9) A] is comparable
with that of the same bond in [Ru(I)(Si(Me)2Ph)(CO)2-
(NH2CH2C6H5)2] [2.848(1) A][46], [Ru(I){C(O)Me}(CO)2-
˚
[43]
˚
(iPr-DAB)] [2.811(9) A]
[2.878(1) A].
and [Ru(I)(Me)(iPr-DAB)(nbd)]
[44]
˚
It is somewhat larger than found for this
bond in [Ru(I)2(CO)2(iPr-DAB)] [2.711(8) A]
[32]
˚
and [Ru-
[47]
˚
(I)2(CO)2(pTol-DAB)] [2.708(1) A]
due to the much
larger trans influence of the methyl group compared to IϪ.
˚
The RuϪCO bonds (ca. 1.870 A) are slightly longer than
those of [Ru(Me)(CO)2(iPr-DAB)]ϩOTfϪ [1.847(9) A]
,
[43]
˚
but
comparable
in
length
with
those
of
[43]
˚
[Ru(I){C(O)Me}(CO)2(iPr-DAB)] [1.874(7) A].
Crystal Structure of cis,cis-[Ru(I)(Me)(CO)2(iPr-DAB)]
Results and Discussion
The bond lengths and angles are collected in Table 2,
while the ORTEP drawing of the complex is presented in
Figure 3.
From the various trans,cis- and cis,cis-[Ru(I)-
(Me)(CO)2(α-diimine)] complexes which were synthesised,
two isomers are structurally characterised by X-ray diffrac-
tion, the others by spectroscopic means. After presentation
of the X-ray data, attention will be paid to several aspects
of the synthesis procedure, in particular to the identity of
the intermediates 1 and 2 of this reaction. Finally, the spec-
troscopic data of the complexes will be reported and dis-
cussed.
Figure 3 confirms the cis,cis conformation of the complex
with the methyl ligand in the equatorial plane and the iod-
ide in an axial position. The structural data agree well with
those of the trans,cis isomer discussed above and with those
of the related complexes [Ru(I){C(O)Me}(CO)2(iPr-
DAB)][43]
,
[Ru(Me)(CO)2(iPr-DAB)]ϩOTfϪ[43]
,
[Ru(I)2-
(CO)2(pTol-DAB)][47], [Ru(I)2(CO)2(iPr-DAB)][32], and [Ru-
(I)(Me)(iPr-DAB)(nbd)].[44] The complex has a distorted
octahedral geometry [IϪRuϪC(10) 176.8(7)°]. The iPr-
DAB ligand has a bite angle of 75.7(5)°, which is slightly
smaller than found for the corresponding trans,cis complex
[76.8(2)°]. Since the CO ligand has a smaller trans influence
Crystal Structure of trans,cis-[Ru(I)(Me)(CO)2(iPr-DAB)]
Table 1 presents the bond lengths and bond angles of the
non-hydrogen atoms of the complex. The ORTEP drawing
of Figure 2 shows its trans,cis geometry.
Figure 2. Molecular structure and selected atom numbering of the than the methyl group, the RuϪI bond is shorter [2.754(2)
non-hydrogen atoms (ORTEP drawing at 50% probability) of
˚
A] than in the case of trans,cis-[Ru(I)(Me)(CO)2(iPr-DAB)]
trans,cis-[Ru(I)(Me)(CO)2(iPr-DAB)]
˚
[2.7998(9) A]. The bond lengths given in Table 2 for
RuϪC(9) and RuϪC(11) are not very accurate. In the com-
plex O(9) is divided in such a way that the CO and Me
ligand are both equally distributed over the two possible
positions, resulting in the introduction of two half O posi-
tions [O(9) and O(11)].
Mechanism of the Complex Formation
The reactions leading to the formation of the two isomers
are presented in Scheme 1. The reaction of [Ru3(CO)12]
with MeI in acetonitrile (MeCN) results in the formation
of an unknown product 1a, which has ν(CO) vibrations at
2058(s), 1996(s), and 1637 cmϪ1, and which is converted
thermally into a second species 2a having ν(CO) bands at
2041(s) and 1974(s) cmϪ1. Both 1a and 2a react with an α-
1244
Eur. J. Inorg. Chem. 1998, 1243Ϫ1251

cis,cis- and trans,cis-[Ru(I)(Me)(CO)2(α-diimine)] Complexes
Table 1. Bond lengths and angles of the non-hydrogen atoms of trans,cis-[Ru(I)(Me)(CO)2(iPr-DAB)] with standard deviations in parentheses
FULL PAPER
˚
˚
˚
bond
length [A]
bond
length [A]
bond
length [A]
RuϪI
2.7998(9)
1.870(8)
2.183(9)
1.869(9)
2.111(6)
2.105(6)
C(1)ϪC(2)
C(1)ϪN(1)
C(2)ϪN(2)
C(3)ϪC(4)
C(3)ϪC(5)
C(3)ϪN(1)
1.48(1)
1.25(1)
1.26(1)
1.52(2)
1.37(2)
1.51(1)
C(6)ϪC(7)
C(6)ϪC(8)
C(6)ϪN(2)
C(9)ϪO(9)
C(11)ϪO(11)
1.50(2)
1.52(2)
1.49(1)
1.12(1)
1.14(1)
RuϪC(9)
RuϪC(10)
RuϪC(11)
RuϪN(1)
RuϪN(2)
bonds
angle [°]
bonds
angle [°]
bonds
angle [°]
IϪRuϪC(9)
93.9(3)
175.4(2)
92.4(3)
86.6(2)
89.9(4)
88.5(4)
173.8(3)
97.1(3)
90.4(4)
89.4(3)
C(10)ϪRuϪN(2)
C(11)ϪRuϪN(1)
C(11)ϪRuϪN(2)
N(1)ϪRuϪN(2)
C(2)ϪC(1)ϪN(1)
C(1)ϪC(2)ϪN(2)
C(4)ϪC(3)ϪC(5)
C(4)ϪC(3)ϪN(1)
C(5)ϪC(3)ϪN(1)
C(7)ϪC(6)ϪC(8)
85.1(3)
97.7(3)
172.8(3)
76.8(2)
117.2(7)
116.6(8)
120(1)
C(7)ϪC(6)ϪN(2)
C(8)ϪC(6)ϪN(2)
RuϪC(9)ϪO(9)
RuϪC(11)ϪO(11)
RuϪN(1)ϪC(1)
RuϪN(1)ϪC(3)
C(1)ϪN(1)ϪC(3)
RuϪN(2)ϪC(2)
RuϪN(2)ϪC(6)
C(2)ϪN(2)ϪC(6)
109.2(8)
113.6(9)
178.3(8)
176.1(8)
114.5(5)
123.4(6)
122.0(7)
114.9(5)
123.9(5)
121.2(7)
IϪRuϪC(10)
IϪRuϪC(11)
IϪRuϪN(1)
C(9)ϪRuϪC(10)
C(9)ϪRuϪC(11)
C(9)ϪRuϪN(1)
C(9)ϪRuϪN(2)
C(10)ϪRuϪC(11)
C(10)ϪRuϪN(1)
109.7(9)
116(1)
111.9(9)
Figure 3. Molecular structure and selected atom numbering of the these products by reaction of 1a with iPr-DAB it is tenta-
non-hydrogen atoms (ORTEP drawing at 50% probability) of cis,-
tively concluded that 1a is the acyl derivative of 2a.
cis-[Ru(I)(Me)(CO)2(iPr-DAB)]
The structure of intermediate 2a could not be determined
1
by H-NMR spectroscopy because of its low solubility and
dynamic behaviour on the NMR time scale. Because of this,
[Ru3(CO)12] was allowed to react with benzyl bromide
(BzlBr) instead of with MeI. Intermediate 2b is then formed
as a major product with ν(CO) bands at 2042(s) and 1979(s)
cmϪ1, very similar to those of product 2a. On addition of
one equivalent of iPr-DAB to 2b, cis,cis-[Ru(Br)(Bzl)(CO)2-
(iPr-DAB)] is formed, which in turn transforms within 30
min into the thermodynamically more stable trans,cis iso-
mer. As 2a and 2b selectively produce the cis,cis isomers,
these intermediates will neither represent trans,cis,cis-
[Ru(X)(R)(CO)2(MeCN)2], analogous to trans,cis,cis-
[Ru(Cl)2(CO)2(C6H5CN)2][49] and trans,cis,cis-[Ru(Cl)2-
(CO)2(pyridine)2][50], nor the thermodynamically unfavour-
able all-cis-[Ru(I)(Me)(CO)2(MeCN)2]. The 1H-NMR spec-
diimine ligand. Thus, adding one equivalent of the α-diim- trum of 2b shows that the complex possesses one equivalent
ine to a solution of 2a results in the formation of cis,cis- of both the Bzl and acetonitrile (MeCN) ligands. Intermedi-
[Ru(I)(Me)(CO)2(α-diimine)], which has been structurally ates 2 are therefore proposed to be the dimeric species
characterised with X-ray diffraction for α-diimine ϭ iPr- [Ru(X)(R)(CO)2(MeCN)]2 [X ϭ I, R ϭ Me (2a); X ϭ Br,
DAB (vide supra). The cis,cis isomers transform thermally R ϭ Bzl (2b)]. Figure 4 presents four possible structures of
1
within 3Ϫ7 days into the trans,cis isomers. On reaction of this dimer. The H-NMR spectrum of 2b clearly shows a
a cis,cis isomer with AgOTf, the halide (IϪ) is replaced by diastereotopic effect on the CH2 group of the benzyl ligand.
OTfϪ. This OTf complex can easily be converted into the Since
a
similar effect is observed for cis,cis-
trans,cis isomer by adding an excess of (nBu)4NI.
[Ru(Br)(Bzl)(CO)2(iPr-DAB)] it is concluded that structures
In order to elucidate the structure of the first product in 2.II of Figure 4 are the most likely ones of 2. For, if 2 had
the reaction sequence, 1a, the reaction between [Ru3(CO)12] one of the 2.I structures, a single resonance would have
and MeI was first brought to completion with formation of been observed for the CH2 group, just as in the case of
product 2a. This solution was then put under 1 atm of CO trans,cis-[Ru(Br)(Bzl)(CO)2(iPr-DAB)]. The formation of
and after 2 h 2a was completely converted into 1a. On ad- the cis,cis-[Ru(X)(R)(CO)2(α-diimine)] complexes from the
dition of one equivalent of iPr-DAB, 1a produced a mixture dimeric intermediates [Ru(X)(R)(CO)2(MeCN)]2 (2) is then
of two complexes in a 4:1 ratio, which are assigned to cis, straightforward. The α-diimine substitutes MeCN (L) and
cis- and trans,cis-[Ru(I){C(O)Me}(CO)2(iPr-DAB)], respec- chelation of this ligand occurs after rupture of an RuϪX
1
tively, with the use of their H-NMR spectra.[48] Attempts bond. As the weaker RuϪX bond trans to R will preferably
to separate the two isomers failed. From the formation of be broken, this celation reaction leads to the formation of
Eur. J. Inorg. Chem. 1998, 1243Ϫ1251
1245

C. J. Kleverlaan, D. J. Stufkens, J. Fraanje, K. Goubitz
Table 2. Bond lengths and angles of the non-hydrogen atoms of cis,cis-[Ru(I)(Me)(CO)2(iPr-DAB)] with standard deviations in parentheses
FULL PAPER
˚
˚
˚
bond
length [A]
bond
length [A]
bond
length [A]
RuϪI
2.754(2)
1.97(2)
1.88(2)
2.01(2)
2.15(1)
2.15(1)
1.45(3)
C(1)ϪN(1)
C(2)ϪN(2)
C(3)ϪC(4)
C(3)ϪN(1)
C(3)ϪC(5a)
C(3)ϪC(5b)
C(6)ϪC(7)
1.28(3)
1.27(3)
1.50(4)
1.55(2)
1.29(8)
1.48(4)
1.50(4)
C(6)ϪN(2)
C(6)ϪC(8a)
C(6)ϪC(8b)
C(9)ϪO(9)
C(10)ϪO(10)
C(11)ϪO(11)
1.51(2)
1.46(8)
1.40(5)
0.99(3)
1.03(3)
0.97(3)
RuϪC(9)
RuϪC(10)
RuϪC(11)
RuϪN(1)
RuϪN(2)
C(1)ϪC(2)
bonds
angle [°]
bonds
angle [°]
bonds
angle [°]
IϪRuϪC(9)
89.8(6)
176.8(7)
89.3(6)
86.6(3)
88.3(4)
88.1(8)
86.7(8)
173.0(7)
98.2(7)
88.2(9)
95.7(7)
94.4(7)
99.3(6)
C(11)ϪRuϪN(2)
N(1)ϪRuϪN(2)
174.5(7)
75.7(5)
118(2)
118(2)
105(1)
135(4)
113(2)
120(4)
118(2)
54(4)
N(2) -C(6)ϪC(8a)
N(2)ϪC(6)ϪC(8b)
C(8a)ϪC(6)ϪC(8b)
RuϪC(9)ϪO(9)
RuϪC(10)ϪO(10)
RuϪC(11)ϪO(11)
RuϪN(1)ϪC(1)
RuϪN(1)ϪC(3)
C(1)ϪN(1)ϪC(3)
RuϪN(2)ϪC(2)
RuϪN(2)ϪC(6)
C(2)ϪN(2)ϪC(6)
116(3)
117(2)
41(4)
IϪRuϪC(10)
IϪRuϪC(11)
C(2)ϪC(1)ϪN(1)
C(1)ϪC(2)ϪN(2)
C(4)ϪC(3)ϪN(1)
C(4)ϪC(3)ϪC(5a)
C(4)ϪC(3)ϪC(5b)
N(1)ϪC(3)ϪC(5a)
N(1)ϪC(3)ϪC(5b)
C(5a)ϪC(3)ϪC(5b)
C(7)ϪC(6)ϪN(2)
C(7)ϪC(6)ϪC(8a)
C(7)ϪC(6)ϪC(8b)
IϪRuϪN(1)
175(2)
178(2)
169(2)
114(1)
124(1)
121(1)
115(1)
125(1)
119(2)
IϪRuϪN(2)
C(9)ϪRuϪC(10)
C(9)ϪRuϪC(11)
C(9)ϪRuϪN(1)
C(9)ϪRuϪN(2)
C(10)ϪRuϪC(11)
C(10)ϪRuϪN(1)
C(10)ϪRuϪN(2)
C(11)ϪRuϪN(1)
107(2)
115(3)
136(2)
1H- and 13C-NMR Spectra
Scheme 1. Proposed mechanism for the reaction of [Ru3(CO)12]
with RX and α-diimine
The structures of the cis,cis and trans,cis isomers of the
iPr-PyCa and dmb complexes were not determined by X-
ray diffraction but were instead deduced from their 1H- and
13C-NMR spectra. The trans,cis-[Ru(I)(Me)(CO)2(iPr-
DAB)] complex has Cs symmetry, and in agreement with
1
this a simple pattern for the H and 13C resonances is ob-
served.[40] The corresponding cis,cis complex has no sym-
metry anymore and two sets of proton and carbon signals
are therefore expected for the coordinated iPr-DAB ligand.
These sets are indeed observed (see Experimental Section).
However, due to the small difference in resonance frequen-
1
cies in both the H- and 13C-NMR spectra, the sets of sig-
nals can not be assigned separately to the two imine parts
of the iPr-DAB ligand positioned trans to the methyl and
CO ligand, respectively.
For the complex trans,cis-[Ru(I)(Me)(CO)2(dmb)] only
one set of signals is observed in the NMR spectra, just as
for trans,cis-[Ru(I)(Me)(CO)2(bpy)].[51] The cis,cis isomer
a cis,cis isomer in which R occupies an equatorial position shows again two sets of resonances in the 1H- and 13C-
and the remaining halide an axial one.
NMR spectra, with small shifts comparable to those ob-
served for the iPr-DAB complex. These H-NMR data ex-
1
clude the formation of the cis(I,Me),cis(CO,CO) complex,
with the iodide equatorial and the methyl group axial. The
1H-NMR spectrum of cis,cis-[Ru(Cl)2(CO)2(R-PyCa)], with
the chloride trans to the imine moiety, shows a resonance
for H6, which is shifted down field by approximately 0.5
ppm with respect to that of H6 in the trans,cis-
[Ru(Cl)2(CO)2(R-PyCa)] complex.[42] This shift is not found
for cis,cis-[Ru(I)(Me)(CO)2(dmb)], and these signals are ac-
cordingly assigned to the latter conformation, with the
methyl in an equatorial and the iodide in an axial position.
The complexes of the asymmetric ligand iPr-PyCa can in
principle form two diastereoisomers (Figure 5), both con-
Figure 4. Relevant structures of [Ru(X)(R)(CO)2(MeCN)]2
1246
Eur. J. Inorg. Chem. 1998, 1243Ϫ1251

cis,cis- and trans,cis-[Ru(I)(Me)(CO)2(α-diimine)] Complexes
FULL PAPER
Figure 5. General molecular structures of the diastereoisomers of (dπ)Ϫhalide (pπ) bonding and anti-bonding character,
cis,cis-[Ru(I)(Me)(CO)2(iPr-PyCa)]
respectively. In the case of the iodide complexes one of the
iodide pπ orbitals has the largest contribution to the
HOMO and the lowest-energy transition of trans,cis-[Ru(I)-
(Me)(CO)2(α-diimine)] has therefore predominant halide to
α-diimine (XLCT) character. The transitions of the higher
energy band have mainly MLCT character.[51]
Table 3. Absorption maxima [nm] and solvatochromism [∆ is
σmax(MeCN) Ϫ σmax(toluene) in cmϪ1] of trans,cis- and cis,cis-[Ru-
1
sisting of two enantiomers. H- and 13C-NMR data reveal
(I)(Me)(CO)2(α-diimine)]
that only one diastereoisomer of cis,cis-[Ru(I)(Me)(CO)2-
(iPr-PyCa)] is formed, since only one set of resonances is
observed for the pyridine and imine moieties of the iPr-
PyCa ligand. This diastereoisomer is proposed to have
structure a (see Figure 5) with a carbonyl ligand trans to
the strongly σ-donating and weakly π-accepting pyridine
moiety and the methyl trans to the more weakly σ-donating
and more strongly π-accepting imine part of the iPr-PyCa
ligand. A similar structure had been found for cis,cis-
[Ru(Cl)2(CO)2(R-PyCa)], which has the chloride in a trans
position with respect to the imine moiety.[42] Based on the
1H- and 13C-NMR data alone, it is not possible to assign
the position of the halide ligand. In order to confirm this
proposal and prove the structure, an NOE-difference
experiment was performed. These spectra show that an in-
teraction exists between the methyl ligand and H6 of the
pyridine moiety. Thus, the methyl ligand coordinates selec-
tively trans with respect to the imine group, which confirms
that the complex has the structure (a) of Figure 5.
It has been shown above that replacement of the methyl
ligand by CO has hardly any influence on the NMR reso-
nances of the trans-positioned α-diimine ligand. In contrast
with this, changing the position of the methyl ligand from
axial (trans to IϪ) to equatorial (trans to the α-diimine) on
going from the trans,cis isomer to the cis,cis isomer, has a
pronounced effect on the NMR signals of the methyl group.
The methyl signals of the cis,cis complexes are observed in
the region δ ϭ 0.78Ϫ0.93, and those of the trans,cis com-
plexes in the region δ ϭ 0.08Ϫ0.10 (1H NMR).[40][41] This
shift is most probably due to through-space interaction be-
tween the methyl and the iodide, when these ligands are in
a cis position.[42]
Compound
λmax
λmax
λmax
∆
(MeCN) (THF)
(toluene)
cis,cis-
384; 344 405; 363 416; 374 2003; 2331
[Ru(I)(Me)(CO)2(dmb)]
trans,cis-
372
397
410
2491
[Ru(I)(Me)(CO)2(dmb)]
cis,cis-
420; 378 438; 394 470; 403 2533; 1641
[Ru(I)(Me)(CO)2(iPr-
PyCa)]
trans,cis-
427; 350
[Ru(I)(Me)(CO)2(iPr-
PyCa)][a]
cis,cis-
460; 383 478; 395 505; 416 1937; 2071
436; 360 463; 374 485; 386 2320; 1870
[Ru(I)(Me)(CO)2(iPr-
DAB)]
trans,cis-
[Ru(I)(Me)(CO)2(iPr-
DAB)][a]
[a]
From ref.[51]
.
Figure 6. Left: Electronic absorption spectra of cis,cis-[Ru-
(I)(Me)(CO)2(α-diimine)] (dmb ϭ ——, iPr-PyCa ϭ ----- and iPr-
DAB ϭ ········) in toluene; right: electronic absorption spectra of
trans,cis- (-----) and cis,cis-[Ru(I)(Me)(CO)2(iPr-DAB)] (——) in to-
luene
Electronic Absorption Spectra
The absorption spectral data of the complexes are col-
lected in Table 3. Figure 6 (left) presents the spectra of the
complexes cis,cis-[Ru(I)(Me)(CO)2(L)] (L ϭ dmb, iPr-PyCa,
and iPr-DAB) in toluene. For comparison the spectra of
A similar two-band system is observed in the spectra of
both trans,cis- and cis,cis-[Ru(I)(Me)(CO)2(iPr-DAB)] in the complexes cis,cis-[Ru(Me)(I)(CO)2(α-diimine)]. Varying
toluene are depicted in Figure 6 (right). the α-diimine ligand from iPr-DAB to iPr-PyCa and dmb
In a previous article it was shown that the trans,cis- causes a shift of both absorption bands to higher energy
[Ru(X)(Me)(CO)2(α-diimine)] (X ϭ halide) complexes pos- (Figure 6). The shifts are closely related to the changes in
sess two visible absorption bands, the relative intensities of energy of the lowest π* orbital of the α-diimine li-
which depend on the halide used.[51] In accordance with a gand.[15][52] In the case of the dmb complex these shifts are
similar behaviour observed for the corresponding fac- and so large, that the second absorption band has almost com-
mer-[Mn(X)(CO)3(bpy)] complexes[36], these two bands pletely disappeared under the much stronger absorptions at
were then assigned to charge transfer transitions to the α- higher energy. In agreement with its CT character, the low-
diimine ligand from two sets of orbitals having metal est-energy band is solvatochromic, shifting to lower energy
Eur. J. Inorg. Chem. 1998, 1243Ϫ1251
1247

C. J. Kleverlaan, D. J. Stufkens, J. Fraanje, K. Goubitz
FULL PAPER
by ca. 2000 cmϪ1 on going from acetonitrile to toluene and 475 cmϪ1. Replacement of CH3 by CD3 in the trans,cis
(Table 3).
isomer causes a shift of the 1194 cmϪ1 band to 909 cmϪ1
,
while the 806 cmϪ1 band is both shifted and split, giving
rise to two new bands at 615 and 599 cmϪ1, respectively.
The positions of the other bands are not affected.
Resonance Raman Spectra
Resonance Raman (rR) spectroscopy is a very valuable
technique for the assignment and characterisation of al-
lowed electronic transitions.[53][54][55][56] Since only those vi-
brations are normally resonance-enhanced, which are vib-
ronically coupled to the electronic transitions, these tran-
sitions can be characterised by the observed resonance ef-
fects. From the three cis,cis isomers rR spectra could only
be recorded for the cis,cis-[Ru(I)(Me)(CO)2(iPr-DAB)] and
cis,cis-[Ru(I)(Me)(CO)2(iPr-PyCa)] complexes. The corre-
sponding dmb complex is too photolabile to provide re-
liable spectra. Spectra were obtained by excitation with the
488.0-nm line of an argon ion laser into the lowest-energy
absorption band of the complexes. The resonantly en-
hanced Raman bands of the complexes are collected in
Table 4. Figure 7 shows the rR spectra of trans,cis-[Ru(I)-
(R)(CO)2(iPr-DAB)] (R ϭ CD3, CH3) and cis,cis-[Ru-
(I)(CH3)(CO)2(α-diimine)] (α-diimine ϭ iPr-DAB, iPr-
PyCa), respectively. The spectra of trans,cis-[Ru(I)(R)(CO)2-
(iPr-DAB)] (R ϭ CD3, CH3) show a strong rR effect for a
band at approximately 1555 cmϪ1, which belongs to
νs(CN), the symmetrical stretching mode of the imine
groups of the iPr-DAB ligand. This band is split in the rR
spectra of the cis,cis isomer, indicating that the two imine
groups of the iPr-DAB ligand are inequivalent due to the
different trans influences of the Me and CO groups. This
effect is not evident from the X-ray structures, but is also
observed in the 1H- and 13C-NMR spectra (vide supra).
The Raman spectrum of cis,cis-[Ru(I)(Me)(CO)2(iPr-PyCa)]
is very similar to that of its trans,cis isomer.[51]
Figure 7. Resonance Raman spectra of (A) trans,cis-[Ru(I)(CD3)-
(CO)2(iPr-DAB)], (B) trans,cis-[Ru(I)(Me)(CO)2(iPr-DAB)], (C) cis,
cis-[Ru(I)(Me)(CO)2(iPr-DAB)], (D) cis,cis-[Ru(I)(Me)(CO)2(iPr-
Ϫ
PyCa)] in KNO3 at 80 K, λexc ϭ 488.0 nm (* ϭ NO3
)
In agreement with the vibrational spectra of
[M(CH3)(CO)5] and [M(CD3)(CO)5] (M ϭ Mn, Re)[57], the
bands at 1194/909 cmϪ1 are assigned to δs(CH3/CD3) and
those at 806/615;599 cmϪ1 to ρ(CH3/CD3). The doublet
spacing of the ρ(CD3) band in [Ru(I)(CD3)(CO)2(iPr-
DAB)] (16 cmϪ1) is rather small compared with that ob-
served
for
[Re(CH3)(CO)5]
(44
cmϪ1 [57]
)
and
[Re(CD3)(CO)3(dmb)] (51 cmϪ1).[58] The rR effect of the
two methyl vibrations is clearly an electronic effect and not
the result of a coupling to other vibrations since the deute-
ration does not affect the frequencies of other Raman
bands. The observation of these CH3/CD3 bands implies
that the charge transfer transition influences the bond
angles of these ligands, most probably as a result of a
change of the hybridisation of the C atom of the CH3 ligand
due to a charge redistribution during the charge transfer
transition.
Table 4. Resonantly enhanced Raman bands of trans,cis- and cis,
cis-[Ru(I)(R)(CO)2(α-diimine)] (R ϭ CH3, CD3; α-diimine ϭ iPr-
DAB, iPr-PyCa), measured at 80 K in KNO3 ֊ft parenthesisλexc ϭ
488.0 nm)
Compound
Raman shift [cmϪ1
]
trans,cis-[Ru(I)(CD3)(CO)2-
(iPr-DAB)]
1555, 1328, 1287, 1132, 909, 615,
599, 475
The observation that deuteration of the methyl ligand
does not affect the frequency of any Raman bands below
800 cmϪ1, leads to the following conclusions. First of all,
the Raman band at approximately 500 cmϪ1 does not be-
long to ν(RuϪCH3) and is assigned to νs(RuϪCO), ex-
pected in this frequency region. Secondly, the absence of a
trans,cis-[Ru(I)(Me)(CO)2-
(iPr-DAB)]
2010, 1553, 1328, 1287, 1194, 806,
475
cis,cis-[Ru(I)(Me)(CO)2-
(iPr-DAB)]
cis,cis-[Ru(I)(Me)(CO)2-
(iPr-PyCa)]
2022, 1568, 1550, 1293, 1198, 806,
486, 395
1620, 1560, 1471, 1291, 1254, 1230,
1194, 1151, 1021, 801, 500, 395
The rather strong rR effect of νs(CN) confirms the charge rR effect for ν(RuϪCH3) implies that the electronic tran-
transfer character of the electronic transition in which exci- sition, in which the excitation takes place, does not influ-
tation takes place. For both isomers there is hardly any rR ence the RuϪmethyl σ bond, although it affects the bond
effect for νs(CO). This means that their charge transfer angles of the methyl ligand. This result agrees with the pro-
transitions do not originate from a central metal orbital posed XLCT character of the transition and excludes the
since this would involve a change of metal-to-CO π back- possibility that the lowest-energy absorption band belongs
bonding and invoke an rR effect for νs(CO). Instead, the to an allowed σ(Ru-methyl)Ǟπ*(α-diimine) transition in-
transition takes place from an orbital having mainly halide stead.
character just as for the trans,cis isomer.[51] In addition, the
According to the rR spectra, the trans,cis and cis,cis iso-
rR spectra of trans,cis- and cis,cis-[Ru(I)(Me)(CO)2(iPr- mers of the [Ru(I)(Me)(CO)2(iPr-DAB)] complexes have
DAB)] show weaker rR effects for bands at 1328, 1194, 806, very similar low-energy transitions. The difference in photo-
1248
Eur. J. Inorg. Chem. 1998, 1243Ϫ1251

cis,cis- and trans,cis-[Ru(I)(Me)(CO)2(α-diimine)] Complexes
FULL PAPER
7.7 Hz, 1 H, py-H4), 7.85 (d, J ϭ 7.7 Hz, 1 H, py-H3), 7.61 (t, J ϭ
5.1 Hz, 1 H, py-H5), 4.20 [sept, 6.3 Hz, 1 H, CH(CH3)2], 1.64/1.52
[d , 6.3 Hz, 6 H, CH(CH3)2], 0.93 (s, 3 H, Ru-Me). Ϫ 13C NMR
APT (CDCl3): δ ϭ 201.1 (Ru-COeq), 194.0 (Ru-COax), 160.2 (Him),
155.5 (py-C2), 149.7 (py-C6), 138.8 (py-C3), 127.7 (py-C5), 126.6
(py-C4), 65.3 [CH(CH3)2], 24.6/23.7 [CH(CH3)2]. Ϫ13.4 (Ru-CH3).
Ϫ IR (CH2Cl2): ν(CO) ϭ 2027 (s), 1956 (s) cmϪ1. Ϫ MS (FABϩ):
M(calcd.) 449.92, M(found) 449.92.
chemistry between trans,cis- and cis,cis-[Ru(I)(Me)-
(CO)2(dmb)], viz. photoisomerization of the trans,cis into
the cis,cis isomer and no apparent product formation of the
cis,cis isomer, can therefore not be ascribed to a different
character of the lowest excited state. This difference in pho-
tochemical behaviour is the subject of a detailed photo-
chemical study of these complexes, the results of which will
be published in a forthcoming article.
1
cis,cis-[Ru(I)(Me)(CO)2(dmb)]: H NMR (CDCl3): δ ϭ 8.85
(d, J ϭ 5.6 Hz, 2 H, py-H6), 7.99/7.96 (s, 2 H, py-H3/py-H3Ј), 7.38/
7.27 (d, J ϭ 5.6 Hz, 1 H, py-H5/py-H5Ј), 2.58/2.55 (s, 6 H, py-Me/
py-MeЈ), 0.89 (s, 3 H, Ru-Me). Ϫ 13C NMR APT (CDCl3): δ ϭ
200.7 (Ru-COeq), 195.6 (Ru-COax), 156.0/153.5(py-C2/py-C2Ј),
153.0/148.8 (py-C6/py-C6Ј), 150.2/149.8 (py-C4/py-C4Ј), 127.1/126.7
(py-C3/py-C3Ј), 123.4/123.2 (py-C5/py-C5Ј), 21.2 (py-CH3), Ϫ14.3
(Ru-CH3). Ϫ IR (CH2Cl2): ν(CO) ϭ 2025 (s), 1952 (s) cmϪ1. ϪMS
(FABϩ): M(calcd.) 483.92, M(found) 483.92.
Prof. A. Oskam is gratefully acknowledged for advice and for
critical reading of the manuscript. Mr J. M. Ernsting is thanked for
measuring the NOE-difference spectrum. Thanks are due to the
Netherlands Foundation for Chemical Research (SON) and the Ne-
therlands Organisation for the Advancement of Pure Research
(NWO) for financial support.
Experimental Section
Synthesis of trans,cis-[Ru(I)(Me)(CO)2(L)] (L ϭ iPr-DAB,
dmb): The complexes trans,cis-[Ru(I)(R)(CO)2(iPr-DAB)] (R ϭ
CH3, CD3), which were used for X-ray structure analysis and Ra-
man spectroscopic measurements, were prepared by the procedure
described by Kraakman et al.[40] The corresponding dmb complex
was prepared from its cis,cis isomer according to the following pro-
cedure. One equivalent of AgOTf was added to a solution of cis,cis-
[Ru(I)(Me)(CO)2(dmb)] in CH2Cl2, which was then stirred for 2 h.
The residue, AgI, was filtered off and 1 g (excess) of (nBu)4NI was
added while light was excluded to prevent photodecomposition.
This solution was stirred for 3 h. The excess of (nBu)4NI and
(nBu)4NOTf was filtered off and the solvent was evaporated. The
complex was purified by column chromatography on silica gel
using gradient elution with CH2Cl2/THF. Yield 80Ϫ90%.
Materials, Apparatus and Preparations: [Ru3(CO)12], MeI, BzlBr,
silver triflate (AgOTf), (nBu)4NI, and 4,4Ј-dimethyl-2,2Ј-bipyridine
(dmb) were used without further purification. Silica gel for column
chromatography (Kieselgel 60, 70Ϫ230 mesh, Merck) was activated
by heating overnight in vacuo at 160°C. Solvents for synthetic pur-
poses were of reagent grade and carefully dried over sodium wire
(THF, n-hexane, diethyl ether) or CaCl2 (CH2Cl2) and freshly dis-
tilled under nitrogen prior to use. Acetonitrile was used without
further purification. Solvents for spectroscopic measurements were
of analytical grade, dried over sodium and distilled under N2 before
use. iPr-DAB and iPr-PyCa were synthesised according to literature
procedures.[59] Electronic absorption spectra were measured with a
Varian Cary 4E spectrophotometer, infrared spectra with an FTS-
60A FTIR spectrometer equipped with a liquid-nitrogen-cooled
MCT detector. Ϫ The 1H-, NOE-difference, and 13C-NMR spectra
were recorded with a Bruker AMX 300 spectrometer (300.13, 75.46
MHz, respectively) at 293K. Resonance Raman measurements were
performed with a Dilor XY spectrometer, using an SP Model 2016
argon ion laser as excitation source. To avoid photodecomposition
the spectra of the complexes (dispersed in a KNO3 pellet) were
measured at 80K. Typical concentrations were 30 mg of complex
and 150 mg of KNO3.
trans,cis-[Ru(I)(Me)(CO)2(dmb)]: 1H NMR (CDCl3): δ ϭ
8.83 (d, J ϭ 5.7 Hz, 2 H, py-H6), 7.96 (s, 2 H, py-H3), 7.30 (d, J ϭ
5.7 Hz, 2 H, py-H5), 2.56 (s, 6 H, py-Me), 0.10 (s, 3 H, Ru-Me). Ϫ
13C NMR APT (CDCl3): δ ϭ 202.2 (Ru-CO), 153.4 (py-C2), 151.6
(py-C6), 150.2 (py-C4), 127.2 (py-C3), 123.5 (py-C5), 21.3 (py-CH3),
Ϫ4.8 (Ru-CH3). Ϫ IR (CH2Cl2): ν(CO) ϭ 2030 (s), 1962 (s) cmϪ1
.
Synthesis of cis,cis-[Ru(I){C(O)Me}(CO)2(iPr-DAB)]: Ru3-
(CO)12 (300 mg, 0.46 mmol) and MeI (1.5 ml, excess) were refluxed
in 20 ml of acetonitrile at 100°C. The reaction was completed after
ca. 1 h; a yellow solution was then obtained containing product 2a
with ν(CO) frequencies of 2041(s) and 1974(s) cmϪ1. The solution
was pressurised with CO (1 atm) and stirred for 2 h. Product 1a
was obtained with ν(CO) of 2058(s) and 1996(s) cmϪ1. After evap-
oration of the solvent, product 1a and 75 mg (0.5 mmol) of iPr-
DAB were dissolved in 10 ml of diethyl ether. After stirring for 1
h, the solution was filtered and the residue was washed with hexane
(2 ϫ 10 ml). The complex was purified by column chromatography
on silica gel using gradient elution with CH2Cl2/THF. Total yield
75% {the 1H-NMR spectrum shows that trans,cis-
Synthesis of cis,cis-[Ru(I)(Me)(CO)2(L)] (L ϭ iPr-DAB, iPr-
PyCa, dmb): Ru3(CO)12 (300 mg, 0.46 mmol) and MeI (1.5 ml,
excess) were refluxed in 20 ml of acetonitrile at 100°C. After 10
min, a product with CO-stretching frequencies at 2058 (s), 1996 (s)
and 1637 (w) was obtained. The reaction was brought to com-
pletion within ca. 1 h; a yellow solution was then obtained which
contained product 2a with CO-stretching frequencies of 2041 (s)
and 1974 (s) cmϪ1. After evaporating the solvent, product 2a was
dissolved in 10 ml of diethyl ether together with 0.5 mmol of the
α-diimine ligand. After stirring for 1 h, the solution was filtered off
and the residue was washed with hexane (2 ϫ 10 ml). The complex
was purified by column chromatography on silica gel using gradient
elution with CH2Cl2/THF. Yield 80Ϫ90%.
[Ru(I){C(O)Me}(CO)2(iPr-DAB)]
[Ru(I){C(O)Me}(CO)2(iPr-DAB)] are formed in a 1:4 ratio}.
trans,cis-[Ru(I){C(O)Me}(CO)2(iPr-DAB)]: NMR
1H
and
cis,cis-
1
cis,cis-[Ru(I)(Me)(CO)2(iPr-DAB)]: H NMR (CDCl3): δ ϭ
8.26/8.20 (s, 1 H, Him), 4.64/4.20 [sept, J ϭ 6.6 Hz, 1 H,
CH(CH3)2], 1.63/1.55/1.49/1.40 [d, J ϭ 6.6 Hz, 3 H, CH(CH3)2],
0.78 (s, 3 H, RuϪMe). Ϫ 13C NMR APT (CDCl3): δ ϭ 200.8 (Ru-
COeq), 193.3 (Ru-COax), 160.1/157.7 (CHim), 65.6/57.2 [CH(CH3)2],
24.8/23.5/23.3/22.2 [CH(CH3)2], Ϫ14.7 (Ru-CH3). Ϫ IR (CH2Cl2):
ν(CO) ϭ 2028 (s), 1958 (s) cmϪ1. Ϫ MS (FABϩ): M(calcd.) 439.95,
M(found) 439.95.
(CDCl3): δ ϭ 8.20 (s, 2 H, Him), 4.24 [sept, J ϭ 6.6 Hz, 2 H,
CH(CH3)2], 2.53 [s, 3 H, Ru-C(O)Me], 1.43/1.38 [d, J ϭ 6.6 Hz, 6
H, CH(CH3)2]. Ϫ IR (CH2Cl2): ν(CO) ϭ 2040 (s), 1974 (s), 1640
(w) cmϪ1
.
cis,cis-[Ru(I){C(O)Me}(CO)2(iPr-DAB)]: 1H NMR (CDCl3):
δ ϭ 8.20/8.18 (1 H, s, Him), 5.15/4.17 [sept, J ϭ 6.6 Hz, 2 H,
CH(CH3)2], 2.81 [s, 3 H, Ru-C(O)Me], 1.69Ϫ1.38 [m, J ϭ 6.6 Hz,
1
cis,cis-[Ru(I)(Me)(CO)2(iPr-PyCa)]: H NMR (CDCl3): δ ϭ 12 H, CH(CH3)2]. Ϫ IR (CH2Cl2): ν(CO) ϭ 2040 (s), 1974 (s), 1640
9.01 (d, J ϭ 5.1 Hz, 1 H, py-H6), 8.48 (s, 1 H, Him), 8.05 (t, J ϭ (w) cmϪ1
.
Eur. J. Inorg. Chem. 1998, 1243Ϫ1251
1249

C. J. Kleverlaan, D. J. Stufkens, J. Fraanje, K. Goubitz
Synthesis of Product 2b: Ru3(CO)12 (300 mg, 0.46 mmol) and CO and CH3 were both equally distributed over the two possible
FULL PAPER
BzlBr (0.5 ml, excess) were refluxed in 20 ml of acetonitrile at
100°C. After completion of the reaction (ca. 0.5 h), a yellow solu-
tion was obtained with product 2b having ν(CO) frequencies of
2042(s) and 1976(s) cmϪ1 and a product with ν(CO) bands at
positions and thus resulting in the introduction of two half occu-
pied O positions (O9 and O11). The disordered C atoms were kept
isotropic during refinement. No attempts were made to calculate
the H atoms for C5a, C5b, C8a and C8b and the H atoms for C3
2077(s) and 2020(s), in a 2:1 ratio. After evaporation of the solvent, and C6 were divided into separate positions and kept fixed entirely
the complex was washed with diethyl ether (2 ϫ 10 ml). Yield 30%.
at their calculated position. The experimental data for the crystal
structure determinations and refinements are listed in Table 5.
Product 2b: 1H NMR (CDCl3): δ ϭ 7.25Ϫ7.15 (m, 4 H, HPh),
2
7.01 (m, 1 H, HPh), 2.96/2.89 (d, J ϭ 8.5 Hz, 2 H, PhCH2), 2.29/
Table 5. Crystallographic data and details of the structure determi-
2.26 (s, 3 H, CH3CN). Ϫ IR (MeCN): ν(CO) ϭ 2042 (s), 1976 nations of trans,cis-[Ru(I)(Me)(CO)2(iPr-DAB)] (A) and cis,cis-[Ru-
(s) cmϪ1
.
(I)(Me)(CO)2(iPr-DAB)] (B)
Synthesis of cis,cis-[Ru(Br)(Bzl)(CO)2(iPr-DyAB)]: Product
2b was prepared in acetonitrile. After evaporation of the solvent,
complex 2b and 0.5 mmol of iPr-DAB were dissolved in 10 ml of
diethyl ether. After stirring for 0.5 h, the solution was filtered off
and the residue was washed with hexane (2 ϫ 10 ml). Yield 50%.
A
B
Crystal data
Chemical formula
Formula weight
Lattice type
Space group
Z
C11H19IN2O2Ru
439.3
monoclinic
P21/n
4
C11H19IN2O2Ru
439.3
monoclinic
P21/n
4
7.409(1)
22.434(8)
10.140(3)
99.31(2)
1663.2(9)
cis,cis-[Ru(Br)(Bzl)(CO)2(iPr-DAB)]: 1H NMR (CDCl3): δ ϭ
8.26/8.24 (s, 1 H, Him), 7.37 (d, J ϭ 7.5 Hz, 2 H, HPh), 7.17 (t, J ϭ
7.5 Hz, 2 H, HPh), 6.95 (t, J ϭ 7.5 Hz, 1 H, HPh), 4.64/4.11 [sept,
˚
a [A]
7.389(2)
22.880(3)
10.540(2)
98.41(1)
1608.7(6)
˚
b [A]
2
˚
J ϭ 6.6 Hz, 1 H, CH(CH3)2], 3.57 (d, J ϭ 7.8 Hz, 1 H, PhCH2),
c [A]
2.98 (d, 2J ϭ 7.8 Hz, 1 H, PhCH2), 1.56Ϫ1.41 [m, 12 H,
β [°]
V [A3]
˚
CH(CH3)2]. Ϫ IR (CH2Cl2): ν(CO) ϭ 2030 (s), 1962 (s) cmϪ1
.
Crystal size [mm]
0.20 ϫ 0.30 ϫ 0.40 0.15 ϫ 0.20 ϫ 0.60
Synthesis of trans,cis-[Ru(Br)(Bzl)(CO)2(iPr-DAB)]: This Dx [g cmϪ3
]
1.81
848
28.5
1.75
848
27.57
complex was prepared by the procedure of Kraakman et al.[40]
F(000)
µ (Mo-Kα) [cmϪ1
Data collection
T [K]
]
trans,cis-[Ru(Br)(Bzl)(CO)2(iPr-DAB)]: 1H NMR (CDCl3):
δ ϭ 8.16 (s, 2 H, Him), 7.10 (t, J ϭ 7.6 Hz, 2 H, HPh), 7.02 (t, J ϭ
7.5 Hz, 1 H, HPh), 6.88 (d, J ϭ 7.5 Hz, 2 H, HPh), 4.22 [sept, J ϭ
6.6 Hz, 2 H, CH(CH3)2], 2.36 (s, 2 H, PhCH2), 1.61/1.38 [d, 12 H,
293
293
˚
λ (Mo-Kα) [A]
0.71069
2.0, 29.9
graphite
1.20 ϩ 0.35tan θ
3.0 ϩ 1.0tan θ
65
0.71069
1.8, 29.9
graphite
1.30 ϩ 0.35tan θ
3.0 ϩ 1.0tan θ
60
θmin, θmax [°]
Monochromator
∆ω [°]
CH(CH3)2]. Ϫ IR (CH2Cl2): ν(CO) ϭ 2033 (s), 1969 (s) cmϪ1
.
Aperture [mm]
Crystal Structure Determination of trans,cis-[Ru(I)(Me)(CO)2-
(iPr-DAB)] and cis,cis-[Ru(I)(Me)(CO)2(iPr-DAB)]: Crystals
of both compounds were grown from a saturated CH2Cl2 solution
at 293 K. Crystals with approximate dimensions 0.20 ϫ 0.30 ϫ
0.40 mm (0.15 ϫ 0.20 ϫ 0.60 mm) were used for data collection
with an Enraf-Nonius CAD-4 diffractometer with graphite-mon-
ochromated Mo-Kα radiation and ω-2θ scan. Totals of 4661 (4819)
unique reflections were measured. Of these, 3168 (1931) were above
the significance level of 2.5 σ(I). The maximum value of (sinθ)/λ
Exposure time [h]
Linear instability [%]
Reference reflections
Dataset
Ϫ
Ϫ
¯
¯
121, 210
161, 122
0/10, 0/29, Ϫ14/14 Ϫ10/0, 0/31, Ϫ13/14
Total unique data
Observed data
DIFABS
4661
4819
1931 (I > 2.5σI)
0.40Ϫ1.53
3168 (I > 2.5σI)
0.68Ϫ1.22
Refinement
R
0.043
0.045
0.065
0.063
Rw
wϪ1
6.0 ϩ 0.012[σ(Fσ)]2 4.0ϩ 0.015[σ(Fσ)]2
was 0.70 AϪ1. Unit-cell parameters were refined by a least-squares
˚
(∆/σ)max
0.45
0.61
Ϫ1.2, 1.0
Min., max. resd. dens. Ϫ0.7, 0.7
fitting procedure using 23 reflections with 40° < 2θ < 41° (40° <
2θ < 42°). Corrections for Lorentz and polarization effects were
applied. The structures were solved by the PATTY option of the
DIRDIF-94 program system.[60] Hydrogen atom positions were
calculated. Full-matrix least-squares refinement of F, anisotropic
for the non-hydrogen atoms and isotropic for the hydrogen atoms,
[eA3]
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˚
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