Syntheses, spectroscopy and crystal structures of (R)-N-(1-Aryl-ethyl) salicylaldimines and [Rh{(R)-N-(1-aryl-ethyl)salicylaldiminato} (η4-cod)] complexes

Article abstract of DOI:10.1515/znb-2007-0609

Condensation of salicylaldehyde with enantiopure (R)-(1-aryl-ethyl)amines yields the enantiopure Schiff bases (R)-N-(1-aryl-ethyl)salicylaldimine (HSB*; aryl = phenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl (4), 4-bromophenyl (5), 2-naphthyl). These Schiff bases readily react with dinuclear (acetato)(η⁴-cycloocta-1,5-diene)rhodium(I), [Rh(μ-O₂CMe)(η⁴-cod)]₂, to afford the mononuclear complexes, cyclooctadiene-((R)-N-(1-aryl-ethyl)salicylaldiminato- κ²N,O)-rhodium(I), [Rh(SB*)(η⁴-cod)] (SB* = deprotonated chiral Schiff base = salicylaldiminate; aryl = phenyl (7), 2-methoxyphenyl, 4-methoxyphenyl, 4-bromophenyl, 2-naphthyl). The complexes have been characterized by IR, UV/vis, ¹H/¹³C NMR and mass spectrometry, optical rotation as well as by single-crystal X-ray structure determination for 4, 5 and 7. The structure of 5 shows C-Br π contacts. Compound 7 is only the second example of a Rh(η⁴-cod) complex with a six-membered Rh-N,O-chelate ring.

Full text of DOI:10.1515/znb-2007-0609

Syntheses, Spectroscopy and Crystal Structures of
(R)-N-(1-Aryl-ethyl)salicylaldimines and
[Rh{(R)-N-(1-aryl-ethyl)salicylaldiminato}(η4-cod)] Complexes
Mohammed Enamullaha, A. K. M. Royhan Uddina, Anne-Christine Chamayoub,
and Christoph Janiakb
a Department of Chemistry, Jahangirnagar University, Dhaka-1342, Bangladesh
b Institut fu¨r Anorganische und Analytische Chemie, Universita¨t Freiburg, Albertstr. 21,
D-79104 Freiburg, Germany
Reprint requests to Prof. M. Enamullah. Fax: +8802-7708069.
E-mail: menam@juniv.edu/enamullahju@yahoo.com or to
Prof. C. Janiak. Fax: +49-7612036147. E-mail: janiak@uni-freiburg.de
Z. Naturforsch. 2007, 62b, 807 – 817; received December 21, 2006
Condensation of salicylaldehyde with enantiopure (R)-(1-aryl-ethyl)amines yields the enantiop-
ure Schiff bases (R)-N-(1-aryl-ethyl)salicylaldimine (HSB∗; aryl = phenyl, 2-methoxyphenyl, 3-
methoxyphenyl, 4-methoxyphenyl (4), 4-bromophenyl (5), 2-naphthyl). These Schiff bases read-
ily react with dinuclear (acetato)(η4-cycloocta-1,5-diene)rhodium(I), [Rh(µ-O2CMe)(η4-cod)]2, to
afford the mononuclear complexes, cyclooctadiene-((R)-N-(1-aryl-ethyl)salicylaldiminato-κ2N,O)-
rhodium(I), [Rh(SB∗)(η4-cod)] (SB∗ = deprotonated chiral Schiff base = salicylaldiminate; aryl =
phenyl (7), 2-methoxyphenyl, 4-methoxyphenyl, 4-bromophenyl, 2-naphthyl). The complexes have
1
been characterized by IR, UV/vis, H/13C NMR and mass spectrometry, optical rotation as well as
by single-crystal X-ray structure determination for 4, 5 and 7. The structure of 5 shows C–Br···π
contacts. Compound 7 is only the second example of a Rh(η4-cod) complex with a six-membered
Rh-N,O-chelate ring.
Key words: (R)-Schiff Bases, Rh(η4-cod) Complexes, Chelate Complexes, π Interactions,
Optical Activity, Chirality
Introduction
bis-salicylaldiminate) complexes [14 – 20]. We re-
cently synthesized Rh(η4-cod) complexes containing
chiral amino acids, chiral amino alcohols and tetraden-
tate Schiff bases as co-ligands starting from dinu-
clear [Rh(µ-O2CMe)(η4-cod)]2 [21– 24]. In contin-
uation, we report here the syntheses and characteri-
zations of enantiopure Schiff base compounds HSB∗
and their [Rh(SB∗)(η4-cod)] complexes [SB∗ = (R)-
N-(1-aryl-ethyl)salicylaldiminate, with X = phenyl, 2-
methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl,
4-bromophenyl, 2-naphthyl].
The synthesis of chiral metal complexes is of con-
stant interest [1]. There are continuous developments
of optically active Schiff base ligands (HSB∗) and
their transition metal complexes for applications as
chiral catalysts [2 – 9]. Examples of organometallic
compounds with HSB∗ ligands are the half-sandwich
complexes [Ru(SB∗)X(η6-benzene)] {SB∗ = (S)-N-
1-phenylethylsalicylaldiminate; X = Cl, 4-/2-Me-py,
PPh3}, [M(SB∗)X(η6-arene)] (M = Ru(II), Os(II);
X = Cl, I) [10, 11], [Ru(SB∗)X(η6-p-cymene)] (X =
various monodentate ligands) [12, 13], and [Rh(SB∗)-
(η4-cod)] {SB∗ = (S)-(α)-(2-pyridyl)-salicylaldimin-
ate} [14].
Results and Discussion
Condensation of the salicylaldehyde with enan-
tiopure (R)-(1-aryl-ethyl)amines yields the optically
active (R)-N-(1-aryl-ethyl)salicylaldimines [HSB∗;
aryl = phenyl (1), 2-methoxyphenyl (2), 3-methoxy-
phenyl (3), 4-methoxyphenyl (4), 4-bromophenyl (5),
2-naphthyl (6)] (Scheme 1). Reaction of dinuclear
Bidentate (HSB) and tetradentate (H2SB) Schiff
bases react easily with dinuclear [Rh(µ-X)(η4-cod)]2
(X = Cl, OMe, O2CMe; cod = 1,5-cyclooctadiene)
to give mononuclear [Rh(SB)(η4-cod)] (SB = salicyl-
aldiminate) and dinuclear [{Rh(η4-cod)}2(SB)] (SB =
0932–0776 / 07 / 0600–0807 $ 06.00 © 2007 Verlag der Zeitschrift fu¨r Naturforschung, Tu¨bingen · http://znaturforsch.com
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808
M. Enamullah et al. · (R)-N-(1-Aryl-ethyl)salicylaldimines and their Rh(η4-cod) Complexes
Scheme 1. Synthetic route
to (R)-N-(1-aryl-ethyl)salic-
ylaldimines (HSB∗; 1 – 6).
Scheme 2. Synthetic route to
Rh(SB∗)(η4-cod) (7 – 11).
[Rh(µ-O2CMe)(η4-cod)]2 (cod
=
1,5-cycloocta- low). The upfield resonance at 3.6 – 3.7 ppm is as-
diene) with (R)-N-(1-aryl-ethyl)salicylaldimine in signed to protons ‘trans to O’, and the downfield reso-
toluene/MeOH affords the mononuclear complexes, nance at 4.5 – 4.6 ppm to protons ‘trans to N’ [20, 24 –
cyclooctadiene-{(R)-N-(1-aryl-ethyl)salicylaldimin-
28, 30– 35].
ato-κ2N,O}-rhodium(I), [Rh(SB∗)(η4-cod)] (SB∗
=
Complex [Rh(SB∗)(η4-cod)] (8) with SB∗
(R)-N-(1-(2-methoxyphenyl-ethyl)salicylaldiminate
=
deprotonated chiral Schiff base = salicylaldiminate)
(7 – 11), in Scheme 2.
shows four multiplets at 3.7, 4.3, 4.4 and 4.5 ppm.
1
The H/13C NMR spectra of the Schiff bases 1 – 6 The ortho-OCH3 substituent on the phenyl ligand
and their complexes 7 – 11 correspond well to those of leads to stronger steric interactions with the olefin
related compounds [2, 3, 9 – 11, 25 – 35]. The presence protons in comparison to meta/para-OCH3 and
of o/m/p-OCH3, p-Br and 2-naphthyl groups in 2 – 6 thereby creates sufficient differences in chemical
shifts the proton signals downfield by 0.1 – 0.5 ppm in shifts between ‘left’ and ‘right’ protons. Similar
contrast to those in 1 due to their electron donating in- olefin proton resonances are observed in [M(sal=N-
ductive effect.
o/p-toluene)(η4-cod)] (M = Rh, Ir) [20], showing
three multiplets for o-toluene and two multiplets for
p-toluene (see Table 1). Also, the dinuclear complexes
[(Rh(η4-cod))2(salophen)] [24] and [Rh(µ-hp/µ-mhp)
(η4-cod)]2 [27] show four multiplets.
In the 1H NMR spectra the signals for the exo- and
endo-methylene protons of the rhodium-coordinated
1,5-cyclooctadiene in [Rh(SB∗)(η4-cod)] (7 – 11) each
appear as multiplets at about 1.90 and 2.40 ppm, re-
spectively. The olefinic protons show two multiplets
In CDCl3 the proton signal for CH=N of the Schiff
at 3.6 – 3.7 and 4.5 – 4.6 ppm (except for 8, see be- bases at 8.2 – 8.4 ppm is shifted upon Rh complexa-
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M. Enamullah et al. · (R)-N-(1-Aryl-ethyl)salicylaldimines and their Rh(η4-cod) Complexes
809
Table 1. 13C NMR spectral data (δ in ppm) and J(103Rh–13C) (Hz) in the cod region in Rh(η4-cod) complexes in CDCl3
(unless noted otherwise).
complexes
methylene carbons
olefinic carbons (J(103Rh–13C) in parentheses)
trans to N
trans to O
‘left’
‘right’a
‘left’
‘right’a
[Rh(SB∗)(η4-cod)] (7)
32.5, 32.0, 29.6, 29.2
33.1, 31.7, 30.1, 28.9
32.5, 32.0, 29.6, 29.1
31.1, 30.7, 28.2, 27.9
32.6, 32.1, 29.6, 29.2
32.1, 31.9, 29.6, 29.5
31.7, 31.3, 29.3, 28.8
32.6, 30.3, 29.5, 27.9
32.5, 30.3, 29.5, 27.9
35.0, 33.0, 30.1, 29.0/33.4,
32.1, 30.5, 29.2
85.7 (12.1)
85.0 (12.6)
85.7 (12.2)
84.5 (11.8)
85.8 (11.6)
81.6
85.1 (12.5)
85.8 (11.7)
85.8 (12.5)
89.1/87.7
85.3 (12.3)
84.0 (12.0)
85.3 (12.2)
84.2 (12.2)
85.4 (12.3)
81.3
84.6 (12.5)
84.3 (11.8)
84.3 (12.5)
772/76.6
73.5 (14.2)
74.7 (13.4)
73.6 (14.0)
72.0 (14.6)
73.7 (14.3)
75.4
74 (17.5)
74.3 (14.6)
74.3 (15.0)
74.4/72.8
71.4 (14.6)
71.6 (14.5)
71.2 (14.6)
70.2 (14.1)
71.4 (14.2)
75.1
72.5 (15.0)
69.7 (14.4)
69.7 (15.0)
70.9/72.2
[Rh(SB∗)(η4-cod)] (8)
[Rh(SB∗)(η4-cod)] (9)
[Rh(SB∗)(η4-cod)] (10)
[Rh(SB∗)(η4-cod)] (11)
[Rh(N,O)(η4-cod)] [35]b
[Rh(sal=N-o-tol)(η4-cod)] [20]
[(Rh(η4-cod))2(salophen)] [24]
[(Rh(η4-cod))2(salophen)] [20]
[Rh(µ-hp/-mhp)(η4-cod)]2 [27]c
[Rh(sal=N-CH3/-Ph)(η4-cod)] [20]
[Rh(sal=N-p-tol)(η4-cod)] [20]
[Rh(o-O2NC6H4NH)(η4-cod)] [28]
[{Rh(η4-cod)}2(dcbi)](NHEt3) [29]
[{Rh(η4-cod)}2(salen)] [24]
a
32.1, 28.9/31.3, 29.0
31.4, 29.0
31.3, 29.4
31.2, 30.0
31.7, 28.8
85.3 (12.5)/84.7 (12.5)
84.6 (12.5)
72.8 (12.5)/73.0 (12.5)
72.9 (15)
84.4 (11)
82.7 (13)
85.5 (11.9)
71.8 (11)
71.7 (14)
71.2 (14.2)
b
c
‘left’ and ‘right’ is an arbitrary assignment for the olefinic carbons to either side of a plane bisecting the C=C bond; in C6D6; in
[D8]toluene.
tion to higher field (at 7.8 ppm) and splits into a sym- maxima at λmax = 234 – 244 nm (εmax = 23750–
metrical doublet by about 2.0 Hz (J) due to 103Rh–1H 59700 L·mol−1·cm−1), associated with the intra-ligand
coupling [17, 19]. In [D6]DMSO this signal remains a π → π∗ transition, and at λmax = 388– 394 nm
singlet at 8.0– 8.1 ppm for the complexes.
(εmax = 5000– 14700 L·mol−1·cm−1), associated with
the metal-to-ligand charge transfer (MLCT) transitions
of Rh→(η4-cod) and Rh→SB∗ [21 – 23]. The polari-
metric measurements in CH2Cl2 or CH3Cl exhibit ro-
tations to the left between −95◦ and −170◦ at 578 nm
and 20 ◦C for enantiopure R-Schiff bases, and rotations
to the right between +200◦ and +333◦ at 578 nm and
20 ◦C for the Rh(R-SB∗)-complexes.
The single-crystal structures of the enantiopure
Schiff bases 4 and 5 confirm the molecular composi-
tion and absolute configuration. The molecular struc-
tures are depicted in Figs. 1 and 2, respectively. Bond
In the 13C NMR spectra the cod methylene car-
bon atoms in 7 – 11 give four singlets of equal inten-
sity at δ = 29 – 31 ppm in contrast to only one singlet
in [Rh(O2CMe)(η4-cod)]2 [22] and [Rh(aminocarb-
oxylato)(η4-cod)] [22, 23]. Similarly, the four olefinic
carbon atoms of cod give four doublets due to 103Rh–
13C coupling, two at lower field (84– 86 ppm) which
are assigned to ‘C trans to N’, the other two at higher
field (70 – 75 ppm) assigned to ‘C trans to O’ (see
Table 1) [16, 20, 24, 26, 29, 30]. The observed 103Rh–
13C(olefin) spin-spin coupling constants for ‘C trans
to N’ (ca. J = 12 Hz) and ‘C trans to O’ (ca. J =
14 Hz) agree with data for related mononuclear Rh(η4-
cod) complexes [16, 20, 24, 27, 30, 35] (see Table 1).
The occurrence of four singlets and four doublets is
explained by steric and magnetic anisotropy effects in
addition to the trans influence of the coordinated N,O-
chelate on the carbon resonances [27]. The observed
chemical shift difference between the ‘left’ and ‘right’
carbon atoms trans to the same donor atom are larger
for ‘trans to O’ than for ‘trans to N’ in 7 – 11.
Fig. 1. Molecular structure of 4 with intramolecular hy-
drogen bond. Thermal ellipsoids with 50 % probability. Se-
Mass spectra of the Schiff bases 1 – 6 and the
[Rh(SB∗)(η4-cod)] complexes 7 – 11 show the parent
ion peaks. UV/vis Electronic spectra of the rhodium
complexes feature two broad bands with absorption
˚
lected bond lengths (A) and angles (deg): C13–O2 1.381(3),
C7–N 1.275(3), N–C8 1.481(3); C7–N–C8 119.1(2). Hy-
drogen bonding inter◦action (dashed line) as O–H, H···N,
˚
O···N, O–H···N (A, ): 1.00(3), 1.68(5), 2.580(2), 148(3).
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810
M. Enamullah et al. · (R)-N-(1-Aryl-ethyl)salicylaldimines and their Rh(η4-cod) Complexes
˚
Scheme 3. Bond lengths (A) for Rh–Ccod
and C=Ccod in the two symmetry-independent
molecules in 7.
Fig. 2. Molecular structure of 5 with intramolecular hydro-
gen bond. Thermal ellipsoids with 50 % probability. Selected
˚
bond lengths (A) and angles (deg): C13–Br 1.908(3), C7–N
1.275(3), N–C8 1.473(3); C7–N–C8 118.5(2). Hydrogen
bonding interaction (dashed line) as O–H, H···N, O···N,
˚
O–H···N (A, deg): 0.92(4), 1.72(4), 2.590(3), 156(4).
Fig. 3. Packing diagram of 5 to illustrate the C–H···π and C–
Br···π contacts as dashed lines to the salicyl ring centroid.
lengths are within the expected range. The expected
intramolecular hydrogen bond is observed between the
salicyl-OH group and the imine nitrogen atom [36].
The molecular packing of 4 does not show π-π
interactions [37 – 39] but only a C–H···π interaction
˚
C16–H···(C10–C15) with H···centroid 2.95 A and C–
H···π plane 60◦ [39 – 42]. The molecular packing in
the structure of 5 is influenced by a C–H···π interac-
˚
tion C12–H···(C1–C6) with H···centroid 2.71 A, C–
H···centroid 138◦ and C–H···π plane 52◦, and also
by C–Br···π contacts to the salicyl ring (C1–C6) with
◦
˚
Br···centroid 3.816(1) A, C–Br···centroid 166.0 and
C–Br···π plane 73.4◦ as illustrated in Fig. 3 [43].
The molecular structure of the rhodium complex
7 proves the suggested N,O-chelation of the depro-
tonated Schiff base salicylaldiminato ligand (Fig. 4).
Again bond lengths and their variations are as ex-
pected [12, 16, 23, 24, 26, 27]. Compound 7 is only
the second example of a Rh(η4-cod) complex with a
six-membered Rh-N,O-chelate ring. The other exam-
ple is the dinuclear compound [{Rh(η4-cod)}2(N,N’-
(1,2-phenylene)bis-(salicylaldiminato))] with an achi-
Fig. 4. Molecular structure of the two symmetry-related
˚
molecules of 7. Selected bond lengths (A) and angles (deg):
Rh1–O1 2.0268(13), Rh1–N1 2.085(2), Rh1–Ccod 2.118(3)–
2.161(3), Rh2–O2 2.0388(13), Rh2–N2 2.0840(19), Rh2–
Ccod 2.117(4)–2.168(4); O1–Rh1–N1 90.93(7), O2–Rh2–N2
90.28(6).
or oxygen donor atoms and the ‘left’ and ‘right’ dif-
ferentiation as mirrored in the four olefinic 13C NMR
resonances.
The unit cell in the crystal structure of 7 contains
ral tetradentate Schiff base ligand [15, 16, 44]. The two symmetry-independent molecules which superfi-
cod-ligand in 7 is bound slightly asymmetrically cially appear related by a pseudo two-fold axis. No
(Scheme 3) which reflects the different trans nitrogen classical hydrogen bonds, π-π interactions or C–H···π
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M. Enamullah et al. · (R)-N-(1-Aryl-ethyl)salicylaldimines and their Rh(η4-cod) Complexes
811
contacts are discernible in 7. Van der Waals interac-
tions between the molecules of 7 with their hydropho-
bic surface seem to control the packing.
Atom numbering for
NMR assignemts in
1 – 5 and 7 – 10.
Experimental Section
All reactions were carried out under an atmosphere of dry
1.1 Hz, 2H, H4,6-sal), 7.31 – 7.51 (m, 7H, sal+Ph), 8.70 (s,
1H, H7), 13.55 (br, 1H, OH). – 1H NMR (200 MHz, CDCl3):
δ = 1.46 (d, JHH = 6.7 Hz, 3H, H9), 4.37 (q, JHH = 6.7 Hz,
1H, H8), 6.69 (ddd, JHH = 7.7, 7.4 Hz, JHH = 1.0 Hz, 1H,
H4), 6.79 (d, JHH = 7.9 Hz, 1H, H6), 7.03 – 7.22 (m, 7H,
sal+Ph), 8.22 (s, 1H, H7), 13.43 (br, 1H, OH). – 13C NMR
(50 MHz, CDCl3): δ = 24.9 (C9), 68.5 (C8), 117.0 (C3),
118.6 (C5), 118.9 (C1), 126.4 (C11,15), 127.3 (C13), 128.7
(C12,14), 131.4 (C6), 132.3 (C4), 143.9 (C10), 161.1 (C2),
163.5 (C7). – MS (EI, 70 eV): m/z (%) = 225 (100) [M]+,
121 (65) [M – CH3CC6H5]+, 105 (100) [CH3CHC6H5]+, 77
(10) [C6H5]+. – C15H15NO (225.29): calcd. C 79.97, H 6.71,
N 6.22; found C 79.15, H 6.91, N 6.44.
nitrogen using standard Schlenk techniques. Solvents were
dried and distilled under nitrogen prior to use: toluene, di-
ethyl ether over Na metal; methanol over CaO; chloroform
over CaCl2. IR spectra were recorded on a Bruker Optik
IFS 25 spectrometer from KBr disks at ambient tempera-
ture. UV/vis Spectra were obtained with a Shimadzu UV
3150 spectrophotometer in CH2Cl2 at 20 ◦C. Elemental anal-
yses were carried out on a Vario EL instrument from Ele-
mentaranalysensysteme GmbH. NMR Spectra were run on a
Bruker Avance DPX 200 spectrometer operating at 200 MHz
◦
(1H) and 50 MHz (13C) at 25 C with calibration against
the residual protonated solvent signal (CDCl3: 7.26 (1H) and
77.0 (13C); [D6]DMSO: 2.52 (1H) and 39.5 (13C) ppm).
The NMR grade solvents CDCl3 and [D6]DMSO were de-
oxygenated prior to use. EI- and CI-MS: Thermo-Finnigan
TSQ 700, with NH3 as ionization gas for CI. Polarimet-
ric measurements were carried with a ◦Perkin-Elmer 241 in-
strument in CHCl3and CH2Cl2 at 20 C, and the values of
[α]20 were determined according to the literature [10]. The
starting dinuclear [Rh(O2CMe)(η4-cod)]2 complex was syn-
thesized from [RhCl(η4-cod)]2 [45] according to the liter-
ature [22, 46]. The enantiopure amines (R)-1-phenyl-ethyl-
amine, (R)-(2-methoxyphenyl)ethylamine, (R)-(3-methoxy-
phenyl)ethylamine, (R)-(4-methoxyphenyl)ethylamine, (R)-
(4-bromophenyl)ethylamine and (R)-(2-naphthyl)ethylamine
were used as received from BASF, Ludwigshafen, Germany.
Compounds 2 – 6 were prepared following the same
procedure as described for 1 using (R)-1-(2-methoxyphenyl)
ethylamine, (R)-1-(3-methoxyphenyl)ethylamine, (R)-1-(4-
methoxyphenyl)ethylamine, (R)-1-(4-bromophenyl)ethyl-
amine, and (R)-1-(2-naphthyl)ethylamine, respectively.
(R)-N-(1-(2-Methoxyphenyl)ethyl)salicylaldimine (2)
Yield: 18.0 g (90 %). – [α]20 (c = 0.49, CH2Cl2): −163◦
(578 nm), −255◦ (546 nm). – IR (KBr): ν = 3054 m (H-Ar),
1626 vs (C=N), 1578 vs (C=C) cm−1. – 1H NMR (200 MHz,
CDCl3): δ = 1.65 (d, JHH = 6.6 Hz, 3H, H9), 3.91 (s, 3H,
H16), 5.05 (q, JHH = 6.6 Hz, 1H, H8), 6.92 (ddd, JHH
8.4, 7.6 Hz, JHH = 1.0 Hz, 2H, H4,13), 6.98 (d, JHH
=
=
6.4 Hz, 1H, H6), 7.05 (dd, JHH = 6.5 Hz, JHH = 1.4 Hz,
1H, H3), 7.29 (d, JHH= 7.6 Hz, 2H, H12,14), 7.37 (ddd,
(R)-N-(1-Phenylethyl)salicylaldimine (1)
JHH= 8.0, 7.5 Hz, JHH= 1.6 Hz, 1H, H5), 7.49 (dd, JHH
=
Salicylaldehyde (8.35 mL, 78.36 mmol) was dissolved
into 20 mL of methanol with 2 – 3 drops of conc. H2SO4
added into the solution which was then stirred for 10 min
at r. t. An equimolar amount of (R)-1-phenyl-ethylamine
(10 mL, 78.39 mmol) was added to the solution. The colour
soon changed to bright yellow, and the mixture was refluxed
for 5 – 6 h. Then, the solvent was evaporated to a volume of
to 50 % in vacuo and the yellow solution was left standing at
r. t. for crystallization through slow solvent evaporation. Af-
ter 2 – 3 d, bright-yellow crystals suitable for X-ray measure-
ments were obtained. The crystals were washed three times
7.6 Hz, JHH = 1.6 Hz, 1H, H11), 8.46 (s, 1H, H7), 13.88
(br, 1H, OH). – 13C NMR (50 MHz, CDCl3): δ = 23.7 (C9),
55.8 (C16), 62.1 (C8), 111.0 (C12), 117.5 (C3), 118.8 (C14),
119.4 (C5), 121.3 (C1), 127.4 (C10), 128.6 (C13), 131.8
(C15), 132.3 (C6), 132.6 (C4), 156.7 (C2), 161.9 (C11),
163.9 (C7). – MS (EI, 70 eV): m/z (%) = 255 (35) [M]+,
135 (100) [CH3CHC6H4OMe]+, 105 (5) [CH3CHC6H5]+. –
C16H17NO2 (255.32): calcd. C 75.27, H 6.71, N 5.49; found
C 75.44, H 6.53, N 5.38.
(R)-N-(1-(3-Methoxyphenyl)ethyl)salicylaldimine (3)
Yield: 18.2 g (91 %). – [α]20 (c = 0.42, CH2Cl2): −169◦
◦
with MeOH (5 mL each) and dried in vacuo at 40 – 50 C
for 5 – 6 h to give a bright-yellow product. Yield: 16.60 g
(94 %) (based on salicylaldehyde). – [α]20 (c = 0.84, CHCl3): (578 nm). – IR (KBr): ν = 3053 m (H-Ar), 1624 vs (C=N),
−95◦ (578 nm). – IR (KBr): ν = 3063 m, 3034 m (H-Ar), 1576 vs (C=C) cm−1. – H NMR (200 MHz, CDCl3): δ =
1
1
1627 vs (C=N), 1578 (C=C) cm−1. – H NMR (200 MHz, 1.69 (d, JHH = 6.6 Hz, 3H, H9), 3.87 (s, 3H, H16), 4.58 (q,
[D6]DMSO): δ = 1.59 (d, JHH = 6.7/6.8a Hz, 3H, H9), 4.70 JHH= 6.6 Hz, 1H, H8), 6.89 (ddd, JHH = 7.2, 6.8 Hz, JHH
=
(q, JHH = 6.6 Hz, 1H, H8), 6.93 (dd, JHH = 7.7, 7.2 Hz, JHH
=
1.6 Hz, 2H, H4,12), 6.95 (d, JHH = 6.8 Hz, 2H, H6,13),
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812
M. Enamullah et al. · (R)-N-(1-Aryl-ethyl)salicylaldimines and their Rh(η4-cod) Complexes
7.03 (dd, JHH = 6.2 Hz, JHH = 2.2 Hz, 1H, H3), 7.31 (dd,
JHH = 7.8 Hz, JHH = 1.4 Hz, 1H, H11), 7.39 (ddd, JHH
=
6.8, 6.5 Hz, JHH = 1.4 Hz, 1H, H5), 8.45 (s, 1H, H7), 13.55
(br, 1H, OH). – 13C NMR (50 MHz, CDCl3): δ = 25.3 (C9),
55.6 (C16), 68.8 (C8), 112.7 (C13), 112.9 (C11), 117.4 (C3),
119.0 (C15), 119.2 (C5), 119.3 (C1), 130.1 (C14), 131.8
(C6), 132.7 (C4), 145.9 (C10), 160.3 (C2), 161.5 (C12),
163.9 (C7). – C16H17NO2 (255.32): calcd. C 75.27, H 6.71,
N 5.49; found C 74.89, H 6.47, N 5.36.
Atom numbering for
NMR assignemts in
6 and 11.
183 peaks, with masses given for the slightly more abundant
79Br-containing fragment), 121 (100) [M – CH3CC6H4Br]+,
104 (55) [CH3CHC6H4]+, 77 (10) [C6H5]+. – C15H14NOBr
(304.19): calcd. C 59.23, H 4.64, N 4.60; found C 59.36,
H 4.61, N 4.55.
(R)-N-(1-(4-Methoxyphenyl)ethyl)salicylaldimine (4)
Yield: 18.6 g (93 %). – [α]20 (c = 0.53, CHCl3): −170◦
(578 nm). – IR (KBr): ν = 3054 m (H-Ar), 1626 vs (C=N),
1609, 1578 vs (C=C) cm−1. – 1H NMR (200 MHz, CDCl3):
δ = 1.66 (d, JHH= 6.7 Hz, 3H, H9), 3.85 (s, 3H, H16), 4.57
(q, JHH = 6.7 Hz, 1H, H8), 6.87 – 7.01 (m, 4H, H3-6), 7.26 –
7.39 (m, 4H, H11,12,14,15), 8.43 (s, 1H, H7), 13.58 (br,
(R)-N-(1-(2-Naphthyl)ethyl)salicylaldimine (6)
Yield: 20.0 g (93 %). – [α]20 (c = 0.52, CH2Cl2): −154◦
(578 nm), −173◦ (546 nm). – IR (KBr): ν = 3048 s (H-Ar),
1628 vs (C=N), 1602 s, 1573 vs (C=C) cm−1. – 1H NMR
(200 MHz, [D6]DMSO): δ = 1.69 (d, JHH = 6.7 Hz, 3H,
H9), 4.88 (q, JHH = 6.6 Hz, 1H, H8), 6.94 (ddd, JHH = 7.7,
8.2 Hz, JHH = 1.0 Hz, 2H, H4,6), 7.36 (ddd, JHH = 7.6,
8.4 Hz, JHH = 1.7 Hz, 1H, H5), 7.52 (m, 3H, H3+nap), 7.60
(dd, JHH = 8.5 Hz, JHH = 1.7 Hz, 1H, nap), 7.91 – 7.97 (m,
4H, nap), 8.76 (s, 1H, H7), 13.55 (br, 1H, OH). – 13C NMR
(50 MHz, [D6]DMSO): δ = 24.5 (C9), 67.3 (C8), 116.8
(C3), 119.1 (C5), 119.2 (C1), 125.0 (C15), 125.3 (C16),
126.2 (C19), 126.6 (C12), 127.9 (C17), 128.2 (C14), 128.7
(C11), 132.2 (C6), 132.7 (C13), 132.8 (C4), 133.4 (C18),
141.9 (C10), 160.9 (C2), 164.9 (C7). – MS (EI, 70 eV): m/z
(%) = 275 (80) [M]+, 155 (100) [CH3CHC10H7]+, 121 (20)
[M – CH3CC10H7]+. – C19H17NO (275.35): calcd. C 82.88,
H 6.22, N 5.09; found C 82.54, H 6.10, N 4.96.
1
1H, OH). – H NMR (200 MHz, [D6]DMSO): δ = 1.56 (d,
JHH = 6.8 Hz, 3H, H9), 3.77 (s, 3H, H16), 4.65 (q, JHH
=
6.8 Hz, 1H, H8), 6.88 – 6.99 (m, 4H, H3-6), 7.33 – 7.47 (m,
4H, H11,12,14,15), 8.66 (s, 1H, H7), 13.53 (br, 1H, OH). –
13C NMR (50 MHz, [D6]DMSO): δ = 24.5 (C9), 55.5 (C16),
66.6 (C8), 114.4 (C12,14), 116.8 (C3), 118.9 (C5), 119.1
(C1), 127.8 (C11,15), 132.0 (C6), 132.6 (C4), 136.3 (C10),
158.8 (C2), 160.9 (C13), 164.3 (C7). – MS (EI, 70 eV): m/z
(%) = 255 (85) [M]+, 135 (100) [CH3CHC6H4OMe]+, 121
(20) [M – CH3CC6H4OMe]+, 105 (10) [CH3CHC6H5]+. –
C16H17NO2 (255.32): calcd. C 75.27, H 6.71, N 5.49; found
C 75.01, H 6.71, N 5.31.
(R)-N-(1-(4-Bromophenyl)ethyl)salicylaldimine (5)
Cyclooctadiene-{(R)-N-(1-phenylethyl)salicylaldiminato-
Yield: 22.0 g (92 %). – [α]20 (c = 0.61, CHCl3): −148◦
(578 nm). – IR (KBr): ν = 3049 m (H-Ar), 1616 vs (C=N),
κ2N,O}-rhodium(I) (7)
1
1575 vs (C=C) cm−1. – H NMR (200 MHz, CDCl3): δ =
Two equivalents of (R)-N-(1-phenylethyl)salicylaldimine
1.52 (d, JHH = 6.8 Hz, 3H, H9), 4.43 (q, JHH = 6.8 Hz, 1H, (80.4 mg, 0.36 mmol) and one equivalent of [Rh(O2CMe)
H8), 6.80 (ddd, JHH = 7.4, 6.4 Hz, JHH = 1.0 Hz, 1H, H4), (η4-cod)]2 (96.3 mg, 0.18 mmol) were dissolved in 10 mL of
6.89 (d, JHH = 8.2 Hz, 1H, H6), 7.16 (dd, JHH = 6.2 Hz, toluene/MeOH (5 : 1, v/v) and the solution stirred for 5 – 6 h
JHH = 1.8 Hz, 3H, H3,11,15), 7.24 (ddd, JHH = 6.8, 7.0 Hz, at r. t. The colour soon changed from red-orange to bright-
◦
JHH = 1.8 Hz, 1H, H5), 7.40 (dd, JHH = 4.8 Hz, JHH
=
yellow. Then the solvent was evaporated in vacuo at 50 C.
1.8 Hz, 2H, H12,14), 8.32 (s, 1H, H7), 13.22 (br, 1H, OH). – The product was again dissolved in 10 mL of toluene/MeOH
1H NMR (200 MHz, [D6]DMSO): δ = 1.56 (d, JHH = 6.7 Hz, (5 : 1, v/v), the solution stirred for 30 min and the sol-
3H, H9), 4.69 (q, JHH = 6.6 Hz, 1H, H8), 6.93 (ddd, JHH
7.8, 6.6 Hz, JHH = 1.0 Hz, 2H, H4,6), 7.38 (ddd, JHH
7.7, 6.4 Hz, JHH = 1.7 Hz, 3H, H3,11,15), 7.48 (dd, JHH
=
=
=
vent evaporated in vacuo. This procedure was repeated three
times, and finally the yellow the product was dried in vacuo
(0.1 – 0.2 mbar) at 60 C. Single crystals suitable for X-ray
◦
6.4 Hz, JHH = 1.7 Hz, 1H, H5), 7.57 (dd, JHH = 6.7 Hz, measurements were grown by slow diffusion of diethyl ether
JHH = 1.7 Hz, 2H, H12,14), 8.69 (s, 1H, H7), 13.28 (br, 1H, into a chloroform solution of complex 7 after one week at r. t.
OH). – 13C NMR (50 MHz, [D6]DMSO): δ = 24.5 (C9), 66.6 Yield: 0.130 g (81 %), based on [Rh(O2CMe)(η4-cod)]2. –
(C8), 116.8 (C3), 119.1 (C13), 120.5 (C5), 128.9 (C11,15), UV/vis (7.109 · 10−5 mol mL−1, CH2Cl2): λmax(lgεmax) =
129.4 (C1), 131.8 (C12,14), 132.1 (C6), 132.8 (C4), 143.8 392 nm (3.84), 234 nm (4.57). – [α]20 (c = 0.26, CH2Cl2):
(C10), 160.7 (C2), 165.0 (C7). – MS (EI, 70 eV): m/z (%) = +250◦ (578 nm), +308◦ (546 nm). – [α]20 (c = 0.44, CHCl3):
304 (84) [M]+, 183 (5) [CH3CHC6H4Br]+ 79/81Br isotopic +182◦ (578 nm). – IR (KBr): ν = 3060, 3030 w (H-Ar),
(
pattern clearly visible for patterns following the 304 and 1626 sh (C=N), 1579 vs (C=C) cm−1. – 1H NMR (200 MHz,
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M. Enamullah et al. · (R)-N-(1-Aryl-ethyl)salicylaldimines and their Rh(η4-cod) Complexes
813
[D6]DMSO): δ = 1.63 (d, JHH= 6.9 Hz, 3H, H9), 1.87 (m, 70 eV): m/z (%) = 465 (100) [M]+, 357 (95) [M – cod]+,
4H, CH2codexo), 2.40 (m, 4H, CH2codendo), 3.77 (m, 2H, 327 (12) [M – cod – HCHO]+, 255 (5) [HSB∗]+, 234 (12)
CHcod), 4.41 (m, 3H, H8+CHcod), 6.48 (t, JHH = 7.4/6.3 Hz, [SB – H2O – H2]+, 135 (12) [CH3CHC6H4OMe]+, 103 (5)
1H, H4), 6.64 (d, JHH = 8.8 Hz, 1H, H6), 7.23 (d, JHH
7.8 Hz, 2H, H3,5), 7.28 – 7.39 (m, 5H, H11-15), 8.13 (s, 1H, N 3.01; found C 62.85, H 6.12, N 2.45.
H7). – 1H NMR (200 MHz, CDCl3): δ = 1.58 (d, JHH
=
[Rh]+. – C24H28NO2Rh (465.40): calcd. C 61.94, H 6.06,
=
6.9 Hz, 3H, H9), 1.85 (m, 4H, CH2codexo), 2.43 (m, 4H,
CH2codendo), 3.72 (m, 2H, CHcod), 4.37 (q, JHH = 6.8 Hz,
1H, H8), 4.54 (m, 2H, CHcod), 6.41 (ddd, JHH = 6.8 Hz,
JHH = 1.0 Hz, 1H, H4), 6.77 (d, JHH = 8.5 Hz, 1H, H6), 6.89
(dd, JHH = 6.0 Hz, JHH = 1.8 Hz, 1H, H3), 7.15 – 7.29 (m,
6H, H5,11,12,13,14,15), 7.82 (d, JHH = 2.0 Hz, 1H, H7). –
13C NMR (50 MHz, CDCl3): δ = 22.5 (C9), 29.2, 29.6,
32.0, 32.5 (CH2cod), 60.2 (C8), 71.4 (d, JCRh = 14.6 Hz,
Cyclooctadiene-{(R)-N-(1-(4-methoxyphenyl)ethyl)salicyl-
aldiminato-κ2N,O}-rhodium(I) (9)
Yield: 0.130 g (75 %). – UV/vis (1.398 · 10−4 mol
mL−1, CH2Cl2): λmax(lgεmax) = 392 nm (3.70), 240 nm
(4.38). – [α]20 (c = 0.41, CH2Cl2): +207◦ (578 nm), +280◦
(546 nm). – [α]20 (c = 0.56, CHCl3): +241◦ (578 nm). – IR
(KBr): ν = 3062, 3030 w (H-Ar), 1624 s (C=N), 1577 vs
(C=C) cm−1. – 1H NMR (200 MHz, [D6]DMSO): δ =
1.59 (d, JHH = 6.5 Hz, 3H, H9), 1.88 (m, 4H, CH2codexo),
2.42 (m, 4H, CH2codendo), 3.74 (s, 3H, H16), 3.76 (m,
2H, CHcod), 4.34 (q, JHH = 6.8 Hz, 1H, H8), 4.43 (m,
2H, CHcod), 6.47 (t, JHH = 7.4/6.8 Hz, 1H, H4), 6.63 (d,
JHH = 8.4 Hz, 1H, H6), 6.94 (d, JHH = 8.8 Hz, 2H, H3,5),
7.25 (m, 4H, H11,12,14,15), 8.04 (s, 1H, H7). – 1H NMR
(200 MHz, CDCl3): δ = 1.55 (d, JHH = 6.8 Hz, 3H, H9),
1.88 (m, 4H, CH2codexo), 2.42 (m, 4H, CH2codendo), 3.70
(m, 2H, CHcod), 3.73 (s, 3H, H16), 4.53 (m, 2H, CHcod),
4.32 (q, JHH = 6.8 Hz, 1H, H8), 6.40 (ddd, JHH = 6.8 Hz,
JHH = 1.0 Hz, 1H, H4), 6.81 (m, 2H, H3,6), 6.89 (ddd,
JHH = 6.1 Hz, JHH = 1.8 Hz, 1H, H5), 7.15 – 7.22 (m,
4H, H11,12,14,15), 7.78 (d, JHH = 2.0 Hz, 1H, H7). –
13C NMR (50 MHz, CDCl3): δ = 22.7 (C9), 29.1, 29.6,
CHcod), 73.5 (d, JCRh = 14.2 Hz, CHcod), 85.3 (d, JCRh
=
12.3 Hz, CHcod), 85.7 (d, JCRh = 12.1 Hz, CHcod), 114.6
(C3), 119.7 (C5), 121.8 (C1), 127.7 (C13), 128.0 (C11,15),
129.0 (C12,14), 135.0 (C6), 135.5 (C4), 143.2 (C10), 165.4
(C2), 166.1 (C7). – MS (EI, 70 eV): m/z (%) = 435 (86)
[M]+, 327 (100) [M – cod]+, 225 (16) [HSB∗]+, 224 (12)
[SB]+, 208 (49) [HSB∗ – OH]+, 206 (35) [SB∗ – H2O]+, 105
(30) [CH3CHC6H5]+, 103 (15) [Rh]+, 77 (7) [C6H5]+. –
MS (CI, NH3): m/z (%) = 436 (100) [M + H]+, 327 (10)
[M – cod]+, 226 (85) [HSB∗ + H]+, 225 (10) [HSB∗]+. –
C23H26NORh (435.37): calcd. C 63.45, H 6.02, N 3.22;
found C 63.53, H 6.13, N 3.24.
The same procedure was followed for the synthesis of the
complexes 8 – 11 using the Schiff bases 2 – 6, respectively.
32.0, 32.5 (CH2cod), 55.7 (C16), 59.7 (C8), 71.2 (d, JCRh
=
Cyclooctadiene-{(R)-N-(1-(2-methoxyphenyl)ethyl)salicyl-
14.3 Hz, CHcod), 73.6 (d, JCRh = 14.0 Hz, CHcod), 85.3 (d,
JCRh = 12.2 Hz, CHcod), 85.7 (d, JCRh = 12.2 Hz, CHcod),
114.4 (C12,14), 114.6 (C3), 119.7 (C5), 121.8 (C1), 129.2
(C11,15), 134.9 (C6), 135.2 (C4), 135.5 (C10), 159.2 (C2),
165.2 (C13), 166.0 (C7). – MS (EI, 70 eV): m/z (%) =
465 (70) [M]+, 357 (100) [M – cod]+, 327 (13) [M – cod –
HCHO]+, 255 (21) [HSB∗]+, 238 (41) [HSB∗ – OH]+, 135
(100) [CH3CHC6H4OMe]+, 105 (23) [CH3CHC6H5]+, 103
(15) [Rh]+, 77 (10) [C6H5]+. – MS (CI, NH3): m/z (%) =
466 (85) [M + H]+, 256 (100) [HSB∗ + H]+, 135 (20)
[CH3CHC6H4OMe]+. – C24H28NO2Rh (465.40): calcd.
C 61.94, H 6.06, N 3.01; found C 61.51, H 6.07, N 2.89.
aldiminato-κ2N,O}-rhodium(I) (8)
Yield: 0.135 g (78 %). – UV/vis (8.526 · 10−5 mol
mL−1, CH2Cl2): λmax(lgεmax) = 388 nm (3.80), 236 nm
(4.53). – [α]20 (c = 0.25, CH2Cl2): +200◦ (578 nm), +220◦
(546 nm). – IR (KBr): ν = 3044 w (H-Ar), 1626 s (C=N),
1
1573 vs (C=C) cm−1. – H NMR (200 MHz, CDCl3): δ =
1.54 (d, JHH = 6.9 Hz, 3H, H9), 1.84 (m, 4H, CH2codexo),
2.43 (m, 4H, CH2codendo), 3.73 (m, 1H, CHcod), 3.78 (s,
3H, H16), 4.29 (m, 1H, CHcod), 4.42 (m, 1H, CHcod),
4.50 (m, 1H, CHcod), 4.63 (q, JHH = 6.8 Hz, 1H, H8),
6.38 (ddd, JHH = 6.8 Hz, JHH = 1.0 Hz, 1H, H4), 6.76
(t, JHH = 9.5 Hz, 2H, H3,6), 6.85 (dd, JHH = 6.2 Hz,
JHH = 1.7 Hz, 1H, H5), 6.93 (d, JHH = 7.4 Hz, 1H, H11),
7.15 (ddd, JHH = 6.8 Hz, JHH = 1.6 Hz, 1H, H13), 7.17 –
7.27 (m, 2H, H12,14), 7.73 (d, JHH = 2.0 Hz, 1H, H7). –
Cyclooctadiene-{(R)-N-(1-(4-bromophenyl)ethyl)salicylald-
iminato-κ2N,O}-rhodium(I) (10)
Yield: 0.150 g (79 %). – UV/vis (7.408· 10−5 mol mL−1
,
13C NMR (50 MHz, CDCl3): δ = 22.8 (C9), 28.9, 30.1, CH2Cl2): λmax(lgεmax) = 394 nm (4.09), 244 nm (4.66). –
31.7, 33.1 (CH2cod), 55.9 (C16), 56.9 (C8), 71.6 (d, JCRh
=
[α]20 (c = 0.24, CH2Cl2): +333◦ (578 nm), 479◦ (546 nm). –
14.5 Hz, CHcod), 74.7 (d, JCRh = 13.4 Hz, CHcod), 84.0 (d, [α]20 (c = 0.47, CHCl3): +308◦ (578 nm). – IR (KBr): ν =
JCRh = 12.0 Hz, CHcod), 85.0 (d, JCRh = 12.6 Hz, CHcod), 3045 w (H-Ar), 1620 sh (C=N), 1604 vs (C=C) cm−1. –
111.4 (C12), 114.3 (C3), 119.8 (C14), 120.6 (C5), 121.7 1H NMR (200 MHz, [D6]DMSO): δ = 1.62 (d, JHH
=
(C1), 128.4 (C10), 129.6 (C13), 130.2 (C15), 134.6 (C6), 6.3 Hz, 3H, H9), 1.88 (m, 4H, CH2codexo), 2.40 (m, 4H,
135.5 (C4), 157.1 (C2), 162.5 (C11), 165.9 (C7). – MS (EI, CH2codendo), 3.72 (m, 2H, CHcod), 4.37 (q, JHH = 6.8 Hz,
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814
M. Enamullah et al. · (R)-N-(1-Aryl-ethyl)salicylaldimines and their Rh(η4-cod) Complexes
Table 2. Crystal structure data for 4, 5 and 7.
4
5
7
Formula
Mr
C16H17NO2
C15H14BrNO
304.18
C23H26NORh
435.36
255.31
0.42×0.13×0.12
orthorhombic
P212121
5.724(2)
12.633(5)
19.237(7)
90
1391.1(9)
4
1.219
0.80
544
Cryst. size [mm3]
Crystal system
Space group
0.45×0.21×0.03
orthorhombic
P212121
5.8401(7)
7.6145(10)
31.146(4)
90
1385.0(3)
4
1.459
0.39×0.26×0.12
monoclinic
P21
12.9992(16)
10.2131(13)
14.6849(18)
102.961(2)
1899.9(4)
4
˚
a [A]
˚
b [A]
˚
c [A]
β [deg]
3
˚
V [A ]
Z
Dcalcd [g cm−3
]
1.522
9.10
896
µ(MoKα ) [cm−1
F(000) [e]
]
29.55
616
hkl range
((sinθ)/λ)max [A
Refl. measured
Refl. unique
Rint
7; 16; 25
0.675
12144
1979
0.0504
176
7; −9, 10; −42, 41
17; 13; 19
0.680
17341
8750
0.0182
−1
˚
]
0.677
12448
3358
0.0449
167
0.0587/0.0607
0.017(9)
0.844
0.393/−0.352
Param. refined
469
R(F)/wR(F2)a (all reflexions)
x(Flack)
0.0827/0.1116
0.0295/0.0465
−0.006(16)
0.936
0.388/−0.381
b
GoF (F2)a
1.037
−3
˚
∆ρfin (max/min) [e A
]
0.164/−0.197
a R(F) = [Σ(ꢀFo|−|Fcꢀ)/Σ|Fo|]; wR(F2) = [Σ[w(Fo −Fc2)2]/Σ[w(F02)2]]1/2. – Goodness-of-fit = [Σ[w(Fo −Fc2)2]/(n− p)]1/2. – Weighting
scheme w; a/b = 0.0601/0.0000 for 4, 0.0273/0.0000 for 5 and 0.0201/0.0000 for 7 with w = 1/[σ2(Fo2)+(aP)2 +bP] where P = (max(Fo2 or
0)+2Fc2)/3. – b Anomalous scattering power is too small in combination with the data quality at hand to give a meaningful Flack parameter;
Friedel opposites were therefore merged (MERG 4). The absolute configuration was established by the known absolute configuration of the
starting amine.
2
2
1H, H8), 4.42 (m, 2H, CHcod), 6.49 (t, JHH = 7.6/7.4 Hz, given for the slightly more abundant 79Br-containing frag-
1H, H4), 6.65 (d, JHH = 8.6 Hz, 1H, H6), 7.28 (m, 4H, ment). – C23H25BrNORh (514.27): calcd. C 53.72, H 4.90,
H3,5,11,15), 7.58 (d, JHH = 8.2 Hz, 2H, H12,14), 8.12 (s, N 2.72; found C 53.21, H 5.00, N 2.51.
1H, H7). – 1H NMR (200 MHz, CDCl3): δ = 1.56 (d, JHH
=
6.8 Hz, 3H, H9), 1.88 (m, 4H, CH2codexo), 2.42 (m, 4H,
CH2codendo), 3.66 (m, 2H, CHcod), 4.29 (q, JHH = 6.8 Hz,
1H, H8), 4.55 (m, 2H, CHcod), 6.42 (ddd, JHH = 6.8 Hz,
JHH = 1.0 Hz, 1H, H4), 6.77 (d, JHH = 8.5 Hz, 1H, H6),
6.90 (dd, JHH = 6.2 Hz, JHH = 1.8 Hz, 1H, H3), 7.14 (d,
Cyclooctadiene-{(R)-N-(1-(2-naphthyl)ethyl)salicylaldimin-
ato-κ2N,O}-rhodium(I) (11)
Yield: 0.145 g (81 %). – UV/vis (5.722 · 10−5 mol
mL−1, CH2Cl2): λmax(lgεmax) = 392 nm (4.17), 244 nm
(4.78). – [α]20 (c = 0.35, CH2Cl2): +329◦ (578 nm), +429◦
(546 nm). – IR (KBr): ν = 3053 w, 3040 w (H-Ar), 1622 vs
(C=N), 1577 vs (C=C) cm−1. – 1H NMR (200 MHz,
CDCl3): δ = 1.68 (d, JHH = 6.8 Hz, 3H, H9), 1.89 (m,
4H, CH2codexo), 2.44 (m, 4H, CH2codendo), 3.77 (m, 2H,
CHcod), 4.50 (q, JHH = 6.8 Hz, 1H, H8), 4.57 (m, 2H,
CHcod), 6.35 (ddd, JHH = 6.5, 6.1 Hz, JHH = 1.0 Hz, 1H,
H4), 6.79 (ddd, JHH = 7.8, 7.1 Hz, JHH = 1.5 Hz, 2H, H3,6),
7.16 (ddd, JHH = 6.9, 6.7 Hz, JHH = 1.5 Hz, 1H, H5), 7.38
(ddd, JHH = 8.9, 7.9 Hz, JHH = 1.3 Hz, 2H, nap), 7.42 (d,
JHH = 8.5 Hz, 2H, H11,15), 7.20 (ddd, JHH = 6.8Hz, JHH
=
1.8 Hz, 1H, H5), 7.41 (dd, JHH = 5.8 Hz, JHH = 1.8 Hz,
2H, H12,14), 7.75 (d, JHH = 2.0 Hz, 1H, H7). – 13C NMR
(50 MHz, CDCl3): δ = 21.1 (C9), 27.9, 28.2, 30.7, 31.1
(CH2cod), 58.3 (C8), 70.2 (d, JCRh = 14.1 Hz, CHcod),
72.0 (d, JCRh = 14.6 Hz, CHcod), 84.2 (d, JCRh = 12.2 Hz,
CHcod), 84.5 (d, JCRh = 11.8 Hz, CHcod), 113.4 (C3),
118.2 (C13), 120.5 (C5), 128.1 (C1), 128.3 (C11,15), 130.8
(C12,14), 133.9 (C6), 134.2 (C4), 141.1 (C10), 164.1 (C2),
164.9 (C7). – MS (EI, 70 eV): m/z (%) = 513 (81) [M]+,
405 (96) [M – cod]+, 332 (40) [M – CH3CHC6H4Br + H2]+,
303 (6) [HSB∗]+, 223 (14) [SB∗–Br], 211 (15) [Rhcod]+,
184 (25) [CH3CHC6H4Br + H]+, 104 (8) [CH3CHC6H4]+,
JHH = 6.8 Hz, 1H, nap), 7.72 (m, 4H, nap), 7.82 (d, JHH
=
2.0 Hz, 1H, H7). – 13C NMR (50 MHz, CDCl3): δ = 22.6
(C9), 29.2, 29.6, 32.1, 32.6 (CH2cod), 60.4 (C8), 71.4 (d,
JCRh = 14.2 Hz, CHcod), 73.7 (d, JCRh = 14.3 Hz, CHcod),
85.4 (d, JCRh = 12.3 Hz, CHcod), 85.8 (d, JCRh = 11.6 Hz,
103 (5) [Rh]+
(
79/81Br isotopic pattern clearly visible for
patterns following the 513, 405, and 184 peaks, with masses
Unauthenticated
Download Date | 1/20/17 3:39 PM

M. Enamullah et al. · (R)-N-(1-Aryl-ethyl)salicylaldimines and their Rh(η4-cod) Complexes
815
CHcod), 114.7 (C3), 119.7 (C5), 121.8 (C1), 126.1 (C15), CH3) were calculated with appropriate riding models (AFIX
126.6 (C16), 126.7 (C19), 126.8 (C12), 128.0 (C17), 128.5 43, 13, 23 and 33, respectively) and Ueq(H) = 1.2 Ueq(CH)
(C14), 129.0 (C11), 133.0 (C6), 133.5 (C13), 135.1 (C4), or Ueq(H) = 1.5 Ueq(CH3). Details of the X-ray structure de-
135.6 (C18), 140.7 (C10), 165.6 (C2), 166.1 (C7). – MS terminations and refinements are provided in Table 2. Graph-
(EI, 70 eV): m/z (%) = 485 (64) [M]+, 377 (100) [M – ics were drawn with DIAMOND (Version 3.1c) [50]. Compu-
cod]+, 275 (5) [HSB∗]+, 258 (13) [HSB∗ – OH]+, 155 (7) tations on the supramolecular interactions were carried out
[CH3CHC10H7]+. – C27H28NORh (485.43): calcd. C 66.81, with PLATON for Windows [15].
H 5.81, N 2.89; found C 66.71, H 6.45, N 2.38.
CCDC 636 583 for 4, 636 584 for 5, and 636 585
for 7 contain the supplementary crystallographic data for
this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data request/cif.
X-Ray structure determinations
Data Collection: Bruker AXS with CCD area detector,
temperature 203(2) K, MoKα radiation (λ = 0.71073 A),
˚
graphite monochromator, ω scans, data collection and cell
refinement with SMART [47], data reduction with SAINT [47],
experimental absorption correction with SADABS [48].
Acknowledgements
We thank the Alexander von Humboldt Foundation
Structure Analysis and Refinement: The structure was (AvH), Bonn, for offering a fellowship to M. Enamullah. Our
solved by Direct Methods (SHELXS-97) [49], refinement sincere thanks go to Dr. Klaus Ditrich (ChiPros) at BASF,
was carried out by full-matrix least-squares on F2 using the Ludwigshafen for providing the (R)-(X)ethylamines. We ac-
SHELXL-97 program suite [49]. All non-hydrogen positions knowledge the financial support from the Ministry of Science
were found and refined with anisotropic temperature factors. and Information & Communication Technology (MSICT),
Hydrogen atoms on oxygen (–OH) were found and fully re- Project 2004/05, Dhaka, Bangladesh and from DFG, grant
fined in 4 and 5. Hydrogen atoms on C (phenyl, CH, CH2 and Ja466/14-1.
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