research papers
Ruthenium complexes containing pyridine and phenan-
throline ligands have been widely explored during the last two
decades with regard to the hydrogen-transfer reaction (Moya
et al., 2012, Bhaskar et al., 2016; Khusnutdinova & Milstein;
EtOAc (6:1 v/v). After the solvent had been removed, the
desired product was obtained as a white solid.
Analytical data for L : white solid; yield: 724 mg,
A
1
3.07 mmol, 75%; m.p. 430 K. H NMR (200 MHz, CDCl ): ꢂ
3
2015; Frank & Katritzky, 1976; Fujita et al., 2014).
We have investigated the synthesis of ruthenium(II)
9.10 (dd, H , J = 4.1, 1.9 Hz, 1H), 8.23 (d, Ph, J = 8.5 Hz, 2H),
7
8.15 (d, H , J = 8.4 Hz, 1H), 8.12 (dd, H , J = 8,1, 1.7 Hz, 1H),
4
5
complexes containing polypyridine ligands and their applica-
tion as potential homogeneous catalysts. We found that these
compounds are active in transfer hydrogenation. The active
species has been described as being a ruthenium hydride
complex containing 2,2-bipyridine, phenanthroline and 1,8-
naphthyridine ligands (Aguirre et al., 2001, 2003; Gajardo et
al., 2006; Oyama et al., 2009; Moya et al., 2012, 2013).
7.90 (d, H , J = 8.0 Hz, 1H), 7.41 (m, H , 1H), 7.05 (d, Ph, J =
3 6
13
9.0, 2H), 3.90 (s, p-OMe, 3H). C NMR (75 MHz, CD Cl ): ꢂ
2
2
161.43 (C -Ph, 1C), 159.80 (C , 1C), 156.20 (C , 1C), 153.62
4
2
9
(C , 1C), 137.44 (C , 1C), 136.59 (C , 1C), 129.33 (C - Ph, 1C),
4
7
5
1
126.30 (C -Ph, C -Ph, 2C), 121.32 (C , C , 2C), 114.14 (C ,
10
3
5
6
3
1C), 111.10 (C -Ph, C -Ph, 2C) 55.35 (o-OMe, 1C).
6
2
Analytical data for L : yellow solid; yield: 782 mg,
B
1
In the present article, we report the syntheses of two new
ligands, namely 2-(4-methoxyphenyl)-1,8-naphthyridine, LA,
and 2-(2-methoxyphenyl)-1,8-naphthyridine, L (see Scheme2),
3.31 mmol, 81%. H NMR (200 MHz, CDCl ): ꢂ 9.01 (dd, H ,
3
7
J = 4.0, 2.0 Hz, 1H), 8.19 (d, H , J = 5.0 Hz, 1H), 8.17 (d, H , J =
5
4
4,2 Hz, 1H), 8.14 (dd, H , J = 4.5, 1.9 Hz, 1H), 8.10 (dd, Ph, J =
3
B
and their respective dichloridodicarbonylruthenium(II) com-
plexes cis-dicarbonyldichloridobis[2-(4-methoxyphenyl)-1,8-
8.1, 1.3 Hz, 1H), 7.43 (m, H , 1H), 7.40 (d, Ph, J = 8.5 Hz, 1H),
6
7.13 (dd, Ph, J = 7.5, 0.9 Hz, 1H), 7.03 (d, Ph, J = 8.4 Hz, 1H),
3.89 (s, o-OMe, 3H).
8
naphthyridine-ꢀN ]ruthenium(II), [RuCl (L ) (CO) ] (Ru-A),
2
A 2
2
and cis-dicarbonyldichloridobis[2-(2-methoxyphenyl)-1,8-
8
naphthyridine-ꢀN ]ruthenium(II), [RuCl (L ) (CO) ] (Ru-B).
2
B 2
2
The structures of the complexes and their activity in hydrogen
transfer is discussed.
2.1.2. Synthesis of the complexes. Ligand LA or LB
(1.316 mmol) and [RuCl (CO) ] (0.658 mmol) were mixed in
ethanol–H O (9:1 v/v, 50 ml). The mixture was refluxed for
2
2 n
2
24 h under a nitrogen atmosphere. The precipitate was sepa-
rated by filtration and the solid was washed with ethanol,
acetone, chloroform and diethyl ether. X-ray diffraction
quality crystals were grown from an ethanol–water (10:1 v/v)
mixture.
1
Analytical data for Ru-A: yield 68%; m.p. 610 K. H NMR
(200 MHz, CDCl ): ꢂ 10.54 (dd, H , J = 5.5, 2.2 Hz, 1H), 9.03
3 7
(
J = 8.8 Hz, 1H), 8.68 (d, H4
dd, H7
0
, J = 5.7, 1.8 Hz, 1H), 8.93 (m, H , Ph, 3H), 8.71 (d, H ,
5
4
0
, J = 8.6 Hz, 1H), 8.59 (d, H3
0
, J =
, J = 8.1, 1.8 Hz, 1H), 8.21 (d, H , J =
8
8
4
.6 Hz, 1H), 8.42 (dd, H5
.8 Hz, 1H), 8.1 (dd, H , J = 8.2, 5.5 Hz, 1H), 7.50 (m, Ph , Ph,
6
0
3
0
0
H), 7.21 (dd, H6
0
, J = 8.1, 5.7 Hz, 1H), 6.58 (m, Ph , 2H), 4.14
2
. Experimental
.1. Synthesis and crystallization
.1.1. Synthesis of the ligands. A suspension of 2-amino-
ꢀ1
(
2
s, OMe, 3H), 3.91 (s, OMe, 3H). IR (KBr, cm ) M—CO
050.0, 1988.2. Analysis calculated (%) for C H Cl N O Ru:
C 54.86, H 3.45, N 8.00; found: C 54.09, H 3.95, N 7.98.
2
32
24
2
4
4
2
1
nicotinaldehyde (500 mg, 4.09 mmol), 2- or 4-methoxy-sub-
stituted acetophenone (4.09 mmol) and NaOH (200 mg,
Analytical data for Ru-B: yield 50%; m.p. 560 K. H NMR
(200 MHz, CDCl ): ꢂ 10.54 (dd, H , J = 5.5, 2.0 Hz, 1H), 9.05
, J = 5.5, 1,8 Hz, 1H), 8.93 (m, H , Ph, 3H), 8.68 (d, H
3
7
(dd, H 0
J = 8.6 Hz, 1H), 8.71 (d, H
8.6 Hz, 1H), 8.42 (dd, H 0
8.8 Hz, 1H), 8.10 (dd, H
0
,
4
5
mmol) in EtOH (40 ml) was refluxed under argon for 4 h, as
7
5
, J = 8.8 Hz, 1H), 8.59 (d, H , J =
0
4 3
depicted in Scheme 3. After this period, the solvent was
removed under reduced pressure. The residue was extracted
with CH Cl from an aqueous mixture and the organic layer
, J = 8.1, 1.8 Hz, 1H), 8.21 (d, H , J =
5
3
0
, J = 8.2, 5.5 Hz, 1H), 7.50 (m, Ph, Ph ,
2
2
6
0
4H), 7.21 (dd, H 0
(s, o-OMe, 3H), 3.91 (s, o-OMe, 3H). IR (KBr, cm ) M—CO;
, J = 8.1, 5.7 Hz, 1H), 7.03 (m, Ph , 2H), 4.14
was dried over magnesium sulfate. The product was purified
by column chromatography on silica gel, eluting with CH Cl –
6
ꢀ1
2
2
ꢁ
1
548 Guajardo et al.
Ruthenium(II) carbonyl complexes of 1,8-naphthyridine
Acta Cryst. (2018). C74, 1547–1552