Mononuclear hydridocarbonyl ruthenium complexes incorporating N2O2 bis-chelating ligands

Article abstract of DOI:10.1016/j.jorganchem.2003.12.004

The reactions of [RuH(CO)Cl(PPh₃)₃] with N,N′-bis(salicylidine)-hydrazine (H₂bsh) and N,N′-bis(salicylidine)-p-phenylene diammine (H₂bsp) in presence of KOH in methanol led in the formation of neutral mononuclea

Full text of DOI:10.1016/j.jorganchem.2003.12.004

Journal of Organometallic Chemistry 689 (2004) 879–882
www.elsevier.com/locate/jorganchem
Mononuclear hydridocarbonyl ruthenium complexes
incorporating N2O2 bis-chelating ligands
a
a
a,
b
Manoj Trivedi , Manish Chandra , Daya Shankar Pandey *, M. Carmen Puerta ,
b
Pedro Valerga
a
Department of Chemistry Awadhesh Pratap Singh University, Rewa 486 003, MP, India
Departamento de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorgꢀanica, Facultad de Ciencias,
b
Universidad de Cꢀadiz, 11510 Puerto Real, Cꢀadiz, Spain
Received 18 October 2003; accepted 9 December 2003
Abstract
The reactions of [RuH(CO)Cl(PPh3)3] with N; N0-bis(salicylidine)-hydrazine (H2bsh) and N; N0-bis(salicylidine)-p-phenylene
diammine (H2bsp) in presence of KOH in methanol led in the formation of neutral mononuclear complexes with the formulations
[RuH(CO)(PPh3)2(L)] (L@Hbsh or Hbsp). These present the first examples where the ligands H2bsh or H2bsp provide only two of
its available donor sites for interaction with the metal centre. The complexes have been characterized by elemental analyses, FAB-
MS, IR, 1H, 13C, 31P NMR and electronic spectral studies. Molecular structure of the representative complex [RuH-
(CO)(PPh3)2(Hbsh)] have been determined by single crystal X-ray analysis.
Ó 2003 Published by Elsevier B.V.
Keywords: Ruthenium; N,N0-bis(salicylidine)-hydrazine(H2bsh); N; N0-bis(salicylidine)-p-phenylene diammine (H2bsp); Mononuclear
1. Introduction
SchiffÕs base ligand N; N0-bis(salicylidine)-hydrazine
wherein, the flexibility of N–N may offer several modes
for interaction with the metal ions and their complexes.
At the same time structurally characterized complexes of
H2bsh are rare, and in the known complexes it adopted
trans configuration [4]. As the ligand possesses four
donor sites in the form of two oxygen and nitrogen
donor atoms, it can act as mono, bi, tri and tetradentate
ligand. In general, it interacts with the metal center
through both of its bis-chelating O, N donor sites
leading to the formation of binuclear complexes. There
are no reports dealing with the complexes of H2bsh in
which, it interacts through only one of its O, N donor
sites to form mononuclear complexes. We have suc-
cessfully isolated and structurally characterized mono-
nuclear complex of the second category from the
interaction of the hydrido carbonyl complex
[RuH(CO)Cl(PPh3)3] with H2bsh. Also, we have iso-
lated mononuclear complex resulting from interaction
of [RuH(CO)Cl(PPh3)3] with closely related ligand
H2bsp under analogous reaction conditions.
During past couple of decades much attention has
been paid towards synthesis and characterization of
ruthenium (II) poly-pyridyl complexes because of their
interesting photo-physical and photochemical properties
and their potential use in various fields [1]. In this re-
gard, ligands that can serve as molecular bridges be-
tween metal centers and that also contain delocalized p
electron system have drawn special attention [2]. Be-
cause of our interests in this area we have examined
reactivity of pyridyl azine ligands with metal complexes
under varying conditions and have shown that the N2
diazine linkage in pyridine-2-carbaldehyde azine offers
several possible mononucleating and binucleating
modes due to flexibility of the N–N single bond [3].
Literature survey further revealed that there are only a
few reports dealing with the closely related N2O2 donor
* Corresponding author. Tel./fax: +91-7662-230684.
E-mail address: dsprewa@yahoo.com (D.S. Pandey).
0022-328X/$ - see front matter Ó 2003 Published by Elsevier B.V.
doi:10.1016/j.jorganchem.2003.12.004

880
M. Trivedi et al. / Journal of Organometallic Chemistry 689 (2004) 879–882
2. Results and discussion
We report herein, formation of new mononuclear
complexes [RuH(CO)(PPh3)2(L)] (Complex 1: L ¼
Hbsh; Complex 2: L ¼ Hbsp) which were obtained in
quantitative yield by reaction of the [RuH(CO)
Cl(PPh3)3] with respective ligand in methanol in pres-
ence of KOH as shown in Scheme 1.
The complexes 1 [RuH(CO)(PPh3)2(Hbsh)] and 2
[RuH(CO)(PPh3)2(Hbsp)] were synthesized in excellent
yields and characterized by satisfactory elemental anal-
yses and spectral data [5]. The FAB MS, analytical and
NMR (1H, 1H–1H COSY and 31P) of the complexes
corresponded to their respective formulations. In the
electronic absorption spectrum of the complex 1 and 2
the MLCT transitions appeared in the visible region at
478 (15950), 450 (12300) nm while ligand-centered
transitions were observed at 338 (27550) and 355 (46220)
nm, respectively.
Fig. 1. Molecular structure of the complex 1.
Analytical and spectral data of the complexes 1 and 2
corresponded to mononuclear complexes in which the
ligand H2bsh or H2bsp interacted with the metal centre
through only one of the O, N donor sites of the re-
spective ligand. Further, its authentication was achieved
by single crystal X-ray diffraction analysis of the repre-
sentative complex [RuH(CO)(PPh3)2(Hbsh)] [6]. The
molecular structure of the complex 1 (Fig. 1) shows that
the coordination geometry about the metal centre ru-
thenium is distorted octahedral and is completed by
N(1) and O(1) from Hbsh, P(1) and P(2) from the tri-
phenyl phosphine, C(15) from carbonyl group and H(1).
The N(1)–Ru(1)–O(1) angle is 83.89(11)° which sug-
gested inward bending of the salicylidine moiety and
smaller value of this angle as compared to that of ideal
value of 90° is probably the source of observed distor-
tion. The triphenylphosphine ligands are trans disposed
as indicated by the P(1)–Ru(1)–P(2) angle of 167.47(4)°.
The Ru(1)–P(1) and Ru(1)–P(2) distances are 2.3697(11)
The ligand Hbsh is essentially planar and the C(7)–
N(1)–N(2)–C(8) torsion angle is )166.1(4)°. The Ru(1)
to N(1) bond length is 2.219(4) A. It is comparable to
other Ru(II) ammine complexes and closely related
polypyridyl complex [RuH(CO)(PPh3)2(g2-tptz)]BF4
ꢁ
[8a]. The Ru(1)–O(1) bond is 2.102(3) A and is compa-
rable to those in other Ru (II) complexes [10]. The N(1)–
ꢁ
ꢁ
N(2) bond distance is 1.409(5) A, it can be defined as
single bond and it is comparable with N–N bond length
ꢁ
in ligand H2bsh 1.386(9) A [11]. The C@N bond lengths
C(7)–N(1) and C(8)–N(2) are essentially equal and are
ꢁ
1.287(5) and 1.282(6) A, respectively and can be con-
sidered to have double bond character. The distance
between O(2) and N(2) which are intramolecularly hy-
ꢁ
drogen bonded, is 1.641(5) A and is comparable to those
observed in analogous ligands which are thermochromic
and photochromic in nature [12].
ꢁ
and 2.3499(11) A, respectively. These are essentially
equivalent and comparable to those in the other related
complexes [7]. The Ru(1)–C(15) bond length is 1.815(4)
3. Conclusion
ꢁ
A, which is normal for Ru(II) carbonyls [8]. The Ru(1)–
ꢁ
H(1) distance in the complex cation is 1.27(4) A and
The results reported herein are very promising with
regard to the synthesis of complexes having different co-
ordination modes of the ligand H2bsh. Further, it is well
documented that the phenolato oxygen atom can be easily
displaced by anionic species and coordinating solvents.
Solvolysis of the latter kind is crucial in alkyne insertion.
Due to presence of available reactive sites (Ru–O bonds)
the complexes have the potential of displaying rich in-
sertion chemistry. As N-salicylidine aniline and its de-
rivatives are known to show photochromism and
thermochromism, the complexes based on these ligands
could also find applications in this area. So far, we have
not looked into such possibilities. Follow up is in progress
to synthesize new complexes, to optimize conditions and
to look into reactivity and application of the resulting
is shorter than those found in the complex
[RuH(H2O)(CO)2(PPh3)2]þ (1.7 A) or [RuHCl(PPh3)3]
ꢁ
ꢁ
(1.7 A), and in other related complexes [9].
Scheme 1.

M. Trivedi et al. / Journal of Organometallic Chemistry 689 (2004) 879–882
881
complexes from interaction of N; N0-bis(salicylidine)-hy-
drazine and closely related ligands N; N0-bis(salicylidine)-
p-phenylene diammine and N; N0-bis(salicylidine)-p-bi-
phenylene diammine with metal complexes under varying
conditions.
[3] M. Chandra, A.N Sahay, S.M. Mobin, D.S. Pandey, J. Organo-
met. Chem. 658 (2002) 43.
[4] (a) J. Saroja, V. Manivannan, P. Chakraborty, S. Pal, Inorg.
Chem. 34 (1995) 3099;
(b) S. Gopinathan, S.A. Pardhy, C. Gopinathan, V.G. Puranik,
S.S. Tavale, T.N.G. Row, Inorg. Chim. Acta 111 (1986) 133;
(c) M. Mikuriya, M. Fukuya, Chem. Lett. (1998) 421;
(d) S. Pal, S. Pal, Inorg. Chem. 40 (2001) 4807.
[5] (a) Preparation of [RuH(CO)(PPh3)2(Hbsh)] 1. N; N0-bis(salicyli-
dine)-hydrazine, (H2bsh) (0.240 g, 1 mmol) in methanol (30 ml)
was treated with KOH (0.056 g, 1.0 mmol) and the resulting
suspension was stirred at room temperature for 1.0 h. Slowly the
suspension dissolved and bright orange yellow solution was
obtained. It was filtered through celite to remove any solid
impurities and to the filtrate [RuH(CO)Cl(PPh3)3] (0.953 g, 1.0
mmol) was added and stirred at room temperature for about 20 h.
Orange red compound separated. It was filtered and extracted
with diethyl ether. Upon slow evaporation it gave orange red
flakes in a couple of days quantitatively. The crystals were
separated by filtration dried in vaccuo (0.607 g, 68%). (Found: C,
68.50; H, 4.72; N, 3.27%, C51H42N2O3P2Ru requires C, 68.45; H,
4.70; N, 3.13%; m (cmꢀ1)(Ru–H) 2005, m(CO) 1954, (bands due to
Hbsh, PPh3, and counter anion BFꢀ4 ) 1625, 1593, 1475, 1434,
1394, 1087, 1055, 950.8, 848, 746, 696; dH(CDCl3) 8.127 (s), 7.61
(m), 7.256(m), 6.91 (d, 8.4 Hz), 6.74 (t, 7.2 Hz), 6.56 (d, 7.5 Hz),
6.23 (d, 9 Hz), 6.09 (d, 8.7 Hz), 6.91 (t, 7.2 Hz), (Ru–H) )10.6 (t);
dP(CDCl3) 18.90 (s); UV–VIS. (CHCl3, kmax nm): 478 (15950), 338
(27550), 292 (38400);
4. Supporting information available
Crystallographic data for the complex 1 have been
deposited with the Cambridge Crystallographic Data
Centre, CCDC No. 207465 in CIF format. 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.uk or www://ccdc.cam.ac.uk).
Acknowledgements
We acknowledge CSIR, New Delhi for financial as-
sistance [HRDG 01(1784)/EMR-II/2002], the Head
Department of Chemistry, A.P.S. University, Rewa for
providing laboratory facilities and Sophisticated Ana-
lytical Instrument Facility, Central Drug Research In-
stitute, Lucknow for providing analytical and spectral
facilities.
(b) Preparation of [RuH(CO)(PPh3)2(Hbsp)] 2. Complex 2 was
prepared by the same method as described for complex 1 except
that N; N0-bis(salicylidine)-p-phenylene diammine (H2bsp) was
used in place of N; N0-bis(salicylidine)-hydrazine (H2bsh),. The
complex separated as mustard yellow blocks. (0.590 g, 61%).
Found: C, 70.48; H, 4.72; N, 2.92%, Mþ 969. C57H46N2O3P2Ru
requires C, 70.51; H, 4.74; N, 2.88%, M (969); cmꢀ1 m (Ru–H)
2001, m(CO) 1953.8, (bands due to Hbsp, PPh3 and counter anion
PFꢀ6 ) 1625, 1591, 1477, 1434, 1305, 1091, 997, 840, 775, 746, 696,
516; dH(CDCl3) 9.338 (d, 4.9 Hz), 8.96 (t, 2.3 Hz), 8.791(s), 8.586
(d, 6.7 Hz), 7.983 (d, 3.5 Hz), 7.45 (m, 1H), (Ru–H) )10.9 (t,);
dP(CDCl3) 21.6 (s); UV–VIS. (CHCl3, kmax nm): 450(12300), 355
(46220), 273(48900).
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