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Novel Rh(III) pentamethylcyclopentadienyl and Ru(II) cyclopentadienyl complexes containing 1,3,5-triazine-2,4,6-trithiol in trinucleating mode
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Inorganic Chemistry Communications 11 (2008) 526–530 www.elsevier.com/locate/inoche
Novel Rh(III) pentamethylcyclopentadienyl and Ru(II) cyclopentadienyl complexes containing 1,3,5-triazine-2,4,6-trithiol in trinucleating mode Manoj Trivedi a, Daya Shankar Pandey a,*, Ru-Qiang Zou b, Qiang Xu b,* b
a Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221 005, Uttar Pradesh, India National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan
Received 19 November 2007; accepted 26 December 2007 Available online 8 January 2008
Abstract Two homo-trinuclear complexes [{(g5-C5Me5)RhCl}3(l3-L)] (1) and [{(g5-C5H5)Ru(PPh3)}3(l3-L)] (2) (H3L = 2,4,6-trimercapto1,3,5-triazine) are reported. Both the complexes have been fully characterized by elemental analyses, FAB-MS, IR, NMR, electronic and emission spectral techniques. Molecular structure of 1 has been authenticated by single crystal X-ray diffraction analyses. Complex 1 revealed the strong intra- and inter-molecular C–H X (X = Cl, p) and p–p stacking interactions, which play important roles to stabilize crystal space packing. Furthermore, the p–p interactions in 1 lead to a double-helical motif. Ó 2008 Elsevier B.V. All rights reserved. Keywords: Rhodium–Cp*; Ruthenium–Cp; Trithiocyanuric acid; X-ray; Emission; Weak interactions
Enormous current attention has been paid towards synthesis and characterisation of bi- and polynuclear transition metal complexes. In this regard polyazine ligands viz., triazine, tetraazine and their derivatives have drawn special attention [1]. 1,3,5-Triazine-2,4,6-trithiol (H3L or TMT) is an effective analytical reagent and find potential applications in the removal of univalent and divalent heavy metal ions from waste water [2]. As far as coordination of TMT with metal ions is concerned, it has been established that TMT acts as a versatile ambidentate ligand in a variety of coordination modes viz., monodentate N or S donor [3], bidentate chelating [N,S] [4] or bridging two metal ions through two of the bis-chelating [N,S] donor sets [5]. The trinucleating coordination mode of 2,4,6-trimercapto-1,3,5-triazinide ðC3 N3 S3 3 Þ derived from TMT using all the three available [N,S] donor sites is limited to only a few complexes * Corresponding authors. Tel.: +91 (0) 9450960400 (D.S. Pandey), +81 72 751 9652 (Q. Xu). E-mail addresses: [email protected] (D.S. Pandey), q.xu@aist. go.jp (Q. Xu).
1387-7003/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2007.12.039
[{(g5-CH3C5H4)2TiIII}3(l3-L)] [6], [Os3H(CO)10]3 (TMT) [7], [{(bpy)2/(phen)2RuII}3(l3-L)](ClO4)3 (bpy = 2,20 -bipyridine, phen = 1,10-phenanthroline) [8] and [{(L0 )2RuII}3(l3-L)](ClO4)3, [L = 1,3,5-triazine-2,4,6-trithiolato, L0 = arylazopyridine] [9], [Cu3(C9H23N3)3(C3N3S3)] (ClO4)3 [10a], [Zn3(C9H23N3)3(C3N3S3)](ClO4)3 [10b]. Furthermore, structurally characterized complexes involving trinucleating mode of TMT are rare [9]. On the other hand, the chemistry and photo-physical properties of Rh(III) and Ru(II) derived from [{(g5C5Me5)Rh(l-Cl)Cl}2] and [(g5-C5H5)Ru(PPh3)2Cl] are well documented [11]. The complexes undergo rich variety of chemistry resulting in the formation of interesting neutral and cationic complexes [12]. Despite extensive studies on the complexes derived from [{(g5-C5Me5)Rh(l-Cl)Cl}2] and [(g5-C5H5)Ru(PPh3)2Cl], its reactivity with TMT has yet to be explored. In this regard, we have examined the reactivity of the chloro-bridged rhodium complex [{(g5-C5Me5)Rh(l-Cl)Cl}2] and ruthenium complex [(g5C5H5)Ru(PPh3)2Cl] with TMT in presence of a base, and successfully isolated two novel trinuclear complexes
M. Trivedi et al. / Inorganic Chemistry Communications 11 (2008) 526–530
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879 cm1. It suggested that TMT moiety in both the complexes 1 and 2 exists in aromatic form with covalent metal– sulphur bonds. Bands associated with m(C@N) vibration in 1 and 2 appeared at 1631–1637 cm1 [4,16]. 1H NMR spectral data in d6-DMSO exhibits a distinct singlet associated with g5-Cp* protons at d 1.56 ppm in 1 and g5-Cp protons at 4.70 ppm in 2. The aromatic protons in 2 associated with PPh3, resonated as a broad multiplet in the expected region (7.32–7.82 ppm). The position and integrated intensity of the various resonances corroborated well to the formulation of 1 and 2. Absorption spectra of 1 and 2 in dimethylsulphoxide (see F-3 supporting material) displayed transitions in
[{(g5-C5Me5)RhCl}3(l3-L)] (1) and [{(g5-C5H5)Ru(PPh3)}3(l3-L)] (2) containing TMT in its relatively rare coordination mode. In this paper, we describe reproducible synthesis and spectral properties of both of the homo-trinuclear complexes as well as the crystal structure and the inter-molecular weak interactions in 1. Reaction of the chloro-bridged dimeric rhodium complex [{(g5-C5Me5)Rh(l-Cl)Cl}2] [13] with 1,3,5-triazine2,4,6-trithiol in 1.5:1 stoichiometric ratio in a mixture of dichloromethane and methanol (1:1 v/v) in presence of triethylamine under stirring conditions at RT afforded homo-trinuclear complex [{(g5-C5Me5)RhCl}3(l3-L)] (1). The ruthenium complex [{(g5-C5H5)Ru (PPh3)}3(l3-L)] (2) was synthesized from reaction of [(g5-C5H5)Ru(PPh3)2Cl] [14] with TMT in 3:1 stoichiometric ratio in absolute ethanol under refluxing conditions in reasonably good yield. The Rh and Ru centre in these complexes is a stereogenic centre, it may lead to several stereoisomers, but we have isolated the major product and our studies mainly deal with the major product. A scheme showing the syntheses of 1 and 2 is shown in Scheme 1 [15]. The complexes were isolated as air-stable, non-hygroscopic solids. Complex 1 is soluble in common organic solvents viz., methanol, dichloromethane, chloroform, dimethylformamide and dimethylsulphoxide but insoluble in petroleum ether and diethyl ether. Complex 2 is soluble in dimethylformamide and dimethylsuphoxide, partially soluble in halogenated solvents like dichloromethane, chloroform but insoluble in petroleum ether and diethyl ether. Both the complexes were fully characterised by IR, 1 H NMR, UV–Vis, FAB-MS, electronic and emission spectral studies. Analytical data of the complexes corroborated well to their respective formulations [15]. FAB-MS spectra of both the complexes corresponded well to their formulations (see F-1 and F-2, supporting material). It has been shown that TMT moiety present in aromatic form with covalent metal–sulphur bond displays bands at 1490, 1232 and 879 cm1 [16]. Infrared spectrum of 1 in nujol displayed bands at 1443, 1244 and 888 cm1 whereas corresponding bands in 2 were observed at 1460, 1232,
Fig. 1. ORTEP diagram of 1 (ellipsoids with 50% probability; hydrogen ˚ ) and bond angles atoms are omitted for clarity). Selected bond lengths (A (°) for 1; Rh(1)–N(3) 2.117(5), Rh(1)–Cl(1) 2.4030(17), Rh(1)–S(1) 2.4388(17), Rh(2)–N(1) 2.125(5), Rh(2)–S(2) 2.4581(17), Rh(2)–Cl(2) 2.3915(16), Rh(3)–N(2) 2.123(6), Rh(3)–S(3) 2.4417(18), Rh(3)–Cl(3) 2.391(2), S(1)–C(1) 1.719(6), S(2)–C(2) 1.710(6), S(3)–C(3) 1.695(7), Rh(1)–Cct 1.764, Rh(1)–Cav 2.145, Rh(2)–Cct 1.773, Rh(2)–Cav 2.146, Rh(3)–Cct 1.769, Rh(3)–Cav 2.146, N(3)–Rh(1)–S(1) 67.29(15), N(1)– Rh(2)–S(2) 67.02(14), N(3)–Rh(3)–S(3) 67.28(14), N(3)–Rh(1)–Cl(1) 82.30(15), N(1)–Rh(2)–Cl(2) 86.91(14), N(2)–Rh(3)–Cl(3) 91.39(15), Cl(1)–Rh(1)–S(1) 90.31(6), Cl(2)–Rh(2)–S(2) 90.47(6), Cl(3)–Rh(3)–S(3) 92.98(7).
S Rh
S N
Rh Cl
S
Cl
N N
N
(i)
S
HS
Ru
N N
(ii)
Ph3 P
[1]
(i) [{( η5-C 5Me5 )Rh(μ-Cl)Cl} 2] /Et3N CH 2 Cl2+CH 3 OH(1:1) (ii) [( η 5-C 5H 5)Ru(PPh3 )2Cl] /KOH Absolute Ethanol
Scheme 1.
S
N
N
PPh 3 S
N
SH
Rh Cl
Ru
SH
Ru Ph3P
[2]
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Table 1 Hydrogen bond parameters for 1 D–H A–X a
C(13)–H(13A) Cl(2) C(19)–H(19C) Cl(1)b C(21)–H(21B) Cl(3)c C(29)–H(29C) Cl(2)d C(31)–H(31C) Cl(1)e C(11)–H(11c) C(3) C(11)–H(11A) C(21) C(21)–H(21C) C(7) C(21)–H(21C) C(6) a b c d e
˚) d(H A) (A
˚) D(D A) (A
h(D–H A) (°)
2.78 2.81 2.81 2.73 2.82 2.75 2.85 2.68 2.65
3.692(8) 3.718(9) 3.725(9) 3.680(14) 3.651(8) 3.368 3.555 3.000 3.423
159 157 161 171 146 122 130 158 137
1 x, y, z. x, y, z, 1 x. 1/2 + y, 1/2 z. 1 + x, y, z. x, 1/2 y, 1/2 + z.
the low energy side at 428 nm and 398 nm, respectively. It have been assigned to Mdp!Lp metal to ligand charge transfer transitions (MLCT), while the transitions in the higher energy side at ca. 302–313 nm have been assigned to the intra-ligand p–p* transitions [4,8]. Complexes 1 and 2 were found to be luminescent at ambient temperature in DMSO (see F-4, supporting material). Upon excitation at 313 nm, complex 1 shows weak emission at 380 nm, however excitation at 428 nm (lowest energy MLCT band), emits strongly at 600 nm, this may be attributed to metal to ligand (Rh–L) charge transfer. Similarly, complex 2 upon excitation at 302 nm exhibits broad emission band at 414 nm, but excitation at 398 nm (lowest energy MLCT band), results in emission at 530 nm, which may be attributed to triplet metal-to-ligand charge transfer state (3MLCT) [8,17]. Since,
H3L exhibits emission around 439 nm at room temperature, the observed emissions at 380–414 nm may probably originate from TMT moiety. Crystals of the [{(g5-C5Me5)RhCl}3(l3-L)] (1) suitable for single crystal X-ray diffraction were obtained from CHCl3/diethyl ether by slow diffusion techniques at room temperature [18]. ORTEP depiction of 1 with atom-labels is shown in Fig. 1 and hydrogen bond parameters are listed in Table 1. The TMT ligand in triazenide form is bonded to three rhodium centres using all the three available bis-chelating [N,S] donor sites. Each of the rhodium is coordinated through nitrogen and sulphur atoms of TMT, chloride and Cp* in g5-coordination mode. Considering Cp* as a single coordination site, overall coordination geometry about each rhodium centre is pseudo-tetrahedral or typical piano stool geometry. Average Rh1–Ccp , Rh2–Ccp , Rh3–Ccp distances ˚ ; Rh1–Cct 1.764 A ˚ ), are 2.145 (range 2.133(6)–2.154(7) A ˚ ˚ 2.146 (range 2.125(6)–2.165(7) A; Rh2–Cct 1.773 A) and ˚ (range 2.134(8)–2.157(8) A ˚ ; Rh3–Cct 1.769 A ˚ ), 2.146 A * respectively [19]. The C–C bond lengths within the Cp ring and C–CH3 bond lengths are normal and comparable with those in other Rh–Cp* complexes [20]. The Rh–Cl distance in 1 is normal [Rh(1)–Cl(1) = 2.403(17), Rh(2)–Cl(2) = 2.391(16), Rh(3)–Cl(3) = 2.391(2)] [19]. as the Rh–N bond distances [Rh(1)–N(3) = 2.117(5), Rh(2)–N(1) = 2.125(5), Rh(3)–N(2) = 2.123(6)], which are comparable to Rh–Cl and Rh–N bond distances reported in the literature [19,20]. The angles N–Rh–Cl [N(3)–Rh(1)–Cl(1) = 82.30(15), N(1)–Rh(2)–Cl(2) = 86.91, N(2)–Rh(3)–Cl(3) = 91.39(15)] are normal. The N–Rh–S bite angles are in the range of 67.02(14)–67.29(15)°, which indicates that the bridging
Fig. 2. Double-helical structure in 1 resulting from p–p interaction: (a) wire-frame model and (b) space-filled model.
M. Trivedi et al. / Inorganic Chemistry Communications 11 (2008) 526–530
TMT ligand suffer from a considerable strain [9]. The ˚ [Rh(1)–S(1)], 2.458 A ˚ Rh(III)–S distances are 2.438(17) A ˚ [Rh(2)–S(2)] and 2.441(18) A [Rh(3)–S(3)]. These bond distances are comparable to the one reported in other Rh(III) complexes [21]. Crystal packing in 1 is stabilised by inter- and intramolecular C–H X (X = Cl, p) and p–p interactions. An interesting feature of the crystal packing in 1 is a doublehelical motif (Fig. 2) resulting from p–p interactions. Con˚ tact distances for p–p interactions are 3.36–3.39 A [22a,22b]. C–H Cl type inter- and intra-molecular hydrogen bonds are also present. The C–H Cl contact dis˚ and associated tances are in the range of 2.73–2.82 A angles are in the range 146–159° (see F-5, supporting material). These distances are within the range reported in the literature [22b]. The inter-molecular C–H p weak interactions in 1 results in parallel chain-like structure, in which pentamethylcyclopentadienyl rings are arranged in alternate manner as shown in Fig. 2. Contact distances for ˚ (see C–H p interactions are in the range of 2.66–2.82 A F-6, supporting material). In conclusion, in this work we have presented novel neutral homo-trinuclear rhodium complex [{(g5-C5Me5) RhCl}3(l3-L)] (1) and ruthenium complex [{(g5-C5H5) Ru(PPh3)}3(l3-L)] (2). Coordination of the bridging ligand 2,4,6-trimercapto-1,3,5-triazine in rather rare coordination mode have been established by analytical, spectral and structural studies. To our knowledge complex 1 represents the first example of a structurally characterized trinuclear rhodium complex incorporating 2,4,6-trimercapto-1,3,5triazine as a bridging ligand. Acknowledgements We gratefully acknowledge financial support from council of Scientific and Industrial Research, New Delhi (Senior Research Fellowship to M.T.). We also thank the Head, SAIF, Central Drug Research Institute, Lucknow for analytical and spectral facilities, the Head, Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi and National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka, Japan for extending facilities. Appendix A. Supplementary material CCDC 662727 contains 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. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.inoche.2007.12.039. References [1] (a) P. Gamez, J. Reedijk, Eur. J. Inorg. Chem. (2006) 29; (b) A.M. Churakov, V.A. Tartakovsky, Chem. Rev. 104 (2004) 2601; (c) N. Gimeno, R. Vilar, Coord. Chem. Rev. 250 (2006) 3161.
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M. Trivedi et al. / Inorganic Chemistry Communications 11 (2008) 526–530
(1:1 v/v) (50 ml), chloro-bridged dimeric rhodium complex [{(g5C5Me5) Rh(l-Cl)Cl}2] (0.231 g, 0.37 mmol) and 0.5 ml triethylamine were added. The suspension was stirred at room temperature overnight. Slowly, it gave a clear red solution and finally a dark red coloured compound separated. The red compound thus obtained was filtered, washed with H2O, ethanol, diethyl ether and dried under vacuo. Dark red; Yield: (0.257 g, 70%). Anal. Calc. for C33H45N3S3Cl3Rh3: C, 39.83; H, 4.53; N, 4.23. Found: C, 39.86; H, 4.56; N, 4.03%. IR (cm1, nujol): m = 3450, 2920, 1702, 1637, 1443, 1244, 1154, 1025, 888, 536, 432. 1H NMR (d ppm, 300 MHz, d6DMSO, 298 K): 1.56 (Cp*, s, 45H). FAB-MS: m/z obs. (calcd.), rel. int., assignments: 988 (993), 5 [M+], 958 (957), 60 [MCl]+, 650 (651), 50 [M2Cp*2Cl]+. UV/Vis (nm): kmax (e (dm3 mol1 cm1)) = 428 (36,680), 313 (32,150), 289 (33,110). [{(g5C5H5)Ru(PPh3)}3(l3-L)] (2):To a suspension of 2,4,6-trimercapto1,3,5-triazine (0.044 g, 0.25 mmol) in absolute ethanol (30 ml), KOH (0.042 g, 0.75 mmol) was added and stirred at room temperature for 30.0 min. Slowly it dissolved and gave a clear solution. This solution was treated with [(g5-C5H5)Ru(PPh3)2Cl] (0.546 g, 0.75 mmol) and refluxed overnight under nitrogen atmosphere. The resulting orange red compound was filtered, washed with H2O, ethanol and diethyl ether. Orange red; Yield: (0.765 g, 70%). Anal. Calc. for C72H60N3S3P3Ru3: C, 59.26; H, 4.11; N, 2.88. Found: C, 59.32; H, 4.18; N, 2.86. IR (cm1, nujol): m = 3076, 2950, 1631, 1460, 1232, 1150, 1010, 879, 416. FAB-MS: m/z: obs. (calcd.), rel. int., assignments: 1460 (1458), 40 [M+]; 1195 (1196), 40 [MPPh3]+, 934 (934), 30 [M(PPh3)2]+.1H NMR (d ppm, 300 MHz, CDCl3, 298 K): 7.56 (multiplet, 45H, due to PPh3), 4.70 (s, 15H). UV/Vis (nm): kmax (e (dm3 mol1 cm1)) = 398 (33,570), 302 (34,890). [16] J.R. Bailey, M.J. Hatfield, K.R. Henke, M.K. Krepps, J.L. Otieno, K.D. Simonetti, E.A. Wall, D.A. Atwood, J. Organomet. Chem. 623 (2001) 185. [17] (a) C.-K. Chan, K.-K. Cheung, C.-M. Che, Chem. Commun. (1996) 227; (b) B.K. Santra, M. Menon, C.K. Pal, G.K. Lahiri, J. Chem. Soc., Dalton Trans. (1997) 1387;
[18]
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[22]
(c) S.K. Singh, M. Chandra, S.K. Dubey, D.S. Pandey, Eur. J. Inorg. Chem. (2006) 3954. X-ray data for 1 was collected on Bruker SMART APEX CCD diffractometer using graphite-monochromated Mo Ka radiation ˚ ) at 293(2) K. The structure was solved by direct (k = 0.71073 A methods and refined by using MAXUS-99 and SHELX-97. Nonhydrogen atoms were refined anisotropically. All the hydrogen atoms were geometrically fixed and allowed to refine using a riding model. Non-hydrogen atoms were refined with anisotropic displacement parameters. [{(g5-C5Me5)RhCl}3(l3-L)], C33H45Cl3N3Rh3S3, M = ˚ , b = 24.2357(15) A ˚, 994.98, Monoclinic, P21/c, a = 12.4740(8) A ˚ , b = 106.2500(10)°, V = 3929.5(4) A ˚ 3, Z = 4, Dc = c = 13.5389(9) A 1.682 g cm3, F(0 0 0) = 1992, T = 293(2) K, R1 = 0.0755, wR2 = 0.2173, GOF = 1.552. A total of 25,070 reflections were collected, 9630 unique (Rint = 0.0280). (a) H. Amouri, C. Guyard-Duhayon, J. Vaissermann, Inorg. Chem. 41 (2002) 1397; (b) T. Scheiring, J. Fiedler, W. Kaim, Organometallics 20 (2001) 1437; (c) H. Aneetha, P.S. Zacharias, B. Srinivas, G.H. Lee, Y. Wong, Polyhedron 18 (1999) 299. P. Paul, B. Tyagi, A.K. Bilakhia, D. Parthsarthi, M.M. Bhadbhade, E. Suresh, G. Ramchandraiah, Inorg. Chem. 37 (1998) 5733. (a) A. Abbasi, M. Habibian, M. Sandstro¨m, Acta Cryst. E 63 (2007) 1904; (b) M.Y. Chavan, X.Q. Lin, M.Q. Ahsan, I. Bernal, J.L. Bear, K.M. Kadish, Inorg. Chem. 25 (1986) 1281; (c) E. Fooladi, T. Graham, M.L. Turner, B. Dalhus, P.M. Maitlis, M. Tilset, Dalton Trans. (2002) 975; (d) J.A. Camerano, M.A. Casado, M.A. Ciriano, C. Tejel, L.A. Oro, Dalton Trans. (2005) 3092; (e) M. Doux, N. Me´zailles, L. Ricard, P. Le Floch, P. Adkine, T. Berclaz, M. Geoffroy, Inorg. Chem. 44 (2005) 1147. (a) G.R. Desiraju, Angew. Chem. Int. Ed. Engl. 34 (1995) 2311; (b) G.R. Desiraju, T. Steiner, The Weak Hydrogen Bond in Structural Chemistry and Biology, Oxford University Press, Oxford, 1999.
Inorganic Chemistry Communications 11 (2008) 526–530 www.elsevier.com/locate/inoche
Novel Rh(III) pentamethylcyclopentadienyl and Ru(II) cyclopentadienyl complexes containing 1,3,5-triazine-2,4,6-trithiol in trinucleating mode Manoj Trivedi a, Daya Shankar Pandey a,*, Ru-Qiang Zou b, Qiang Xu b,* b
a Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221 005, Uttar Pradesh, India National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan
Received 19 November 2007; accepted 26 December 2007 Available online 8 January 2008
Abstract Two homo-trinuclear complexes [{(g5-C5Me5)RhCl}3(l3-L)] (1) and [{(g5-C5H5)Ru(PPh3)}3(l3-L)] (2) (H3L = 2,4,6-trimercapto1,3,5-triazine) are reported. Both the complexes have been fully characterized by elemental analyses, FAB-MS, IR, NMR, electronic and emission spectral techniques. Molecular structure of 1 has been authenticated by single crystal X-ray diffraction analyses. Complex 1 revealed the strong intra- and inter-molecular C–H X (X = Cl, p) and p–p stacking interactions, which play important roles to stabilize crystal space packing. Furthermore, the p–p interactions in 1 lead to a double-helical motif. Ó 2008 Elsevier B.V. All rights reserved. Keywords: Rhodium–Cp*; Ruthenium–Cp; Trithiocyanuric acid; X-ray; Emission; Weak interactions
Enormous current attention has been paid towards synthesis and characterisation of bi- and polynuclear transition metal complexes. In this regard polyazine ligands viz., triazine, tetraazine and their derivatives have drawn special attention [1]. 1,3,5-Triazine-2,4,6-trithiol (H3L or TMT) is an effective analytical reagent and find potential applications in the removal of univalent and divalent heavy metal ions from waste water [2]. As far as coordination of TMT with metal ions is concerned, it has been established that TMT acts as a versatile ambidentate ligand in a variety of coordination modes viz., monodentate N or S donor [3], bidentate chelating [N,S] [4] or bridging two metal ions through two of the bis-chelating [N,S] donor sets [5]. The trinucleating coordination mode of 2,4,6-trimercapto-1,3,5-triazinide ðC3 N3 S3 3 Þ derived from TMT using all the three available [N,S] donor sites is limited to only a few complexes * Corresponding authors. Tel.: +91 (0) 9450960400 (D.S. Pandey), +81 72 751 9652 (Q. Xu). E-mail addresses: [email protected] (D.S. Pandey), q.xu@aist. go.jp (Q. Xu).
1387-7003/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2007.12.039
[{(g5-CH3C5H4)2TiIII}3(l3-L)] [6], [Os3H(CO)10]3 (TMT) [7], [{(bpy)2/(phen)2RuII}3(l3-L)](ClO4)3 (bpy = 2,20 -bipyridine, phen = 1,10-phenanthroline) [8] and [{(L0 )2RuII}3(l3-L)](ClO4)3, [L = 1,3,5-triazine-2,4,6-trithiolato, L0 = arylazopyridine] [9], [Cu3(C9H23N3)3(C3N3S3)] (ClO4)3 [10a], [Zn3(C9H23N3)3(C3N3S3)](ClO4)3 [10b]. Furthermore, structurally characterized complexes involving trinucleating mode of TMT are rare [9]. On the other hand, the chemistry and photo-physical properties of Rh(III) and Ru(II) derived from [{(g5C5Me5)Rh(l-Cl)Cl}2] and [(g5-C5H5)Ru(PPh3)2Cl] are well documented [11]. The complexes undergo rich variety of chemistry resulting in the formation of interesting neutral and cationic complexes [12]. Despite extensive studies on the complexes derived from [{(g5-C5Me5)Rh(l-Cl)Cl}2] and [(g5-C5H5)Ru(PPh3)2Cl], its reactivity with TMT has yet to be explored. In this regard, we have examined the reactivity of the chloro-bridged rhodium complex [{(g5-C5Me5)Rh(l-Cl)Cl}2] and ruthenium complex [(g5C5H5)Ru(PPh3)2Cl] with TMT in presence of a base, and successfully isolated two novel trinuclear complexes
M. Trivedi et al. / Inorganic Chemistry Communications 11 (2008) 526–530
527
879 cm1. It suggested that TMT moiety in both the complexes 1 and 2 exists in aromatic form with covalent metal– sulphur bonds. Bands associated with m(C@N) vibration in 1 and 2 appeared at 1631–1637 cm1 [4,16]. 1H NMR spectral data in d6-DMSO exhibits a distinct singlet associated with g5-Cp* protons at d 1.56 ppm in 1 and g5-Cp protons at 4.70 ppm in 2. The aromatic protons in 2 associated with PPh3, resonated as a broad multiplet in the expected region (7.32–7.82 ppm). The position and integrated intensity of the various resonances corroborated well to the formulation of 1 and 2. Absorption spectra of 1 and 2 in dimethylsulphoxide (see F-3 supporting material) displayed transitions in
[{(g5-C5Me5)RhCl}3(l3-L)] (1) and [{(g5-C5H5)Ru(PPh3)}3(l3-L)] (2) containing TMT in its relatively rare coordination mode. In this paper, we describe reproducible synthesis and spectral properties of both of the homo-trinuclear complexes as well as the crystal structure and the inter-molecular weak interactions in 1. Reaction of the chloro-bridged dimeric rhodium complex [{(g5-C5Me5)Rh(l-Cl)Cl}2] [13] with 1,3,5-triazine2,4,6-trithiol in 1.5:1 stoichiometric ratio in a mixture of dichloromethane and methanol (1:1 v/v) in presence of triethylamine under stirring conditions at RT afforded homo-trinuclear complex [{(g5-C5Me5)RhCl}3(l3-L)] (1). The ruthenium complex [{(g5-C5H5)Ru (PPh3)}3(l3-L)] (2) was synthesized from reaction of [(g5-C5H5)Ru(PPh3)2Cl] [14] with TMT in 3:1 stoichiometric ratio in absolute ethanol under refluxing conditions in reasonably good yield. The Rh and Ru centre in these complexes is a stereogenic centre, it may lead to several stereoisomers, but we have isolated the major product and our studies mainly deal with the major product. A scheme showing the syntheses of 1 and 2 is shown in Scheme 1 [15]. The complexes were isolated as air-stable, non-hygroscopic solids. Complex 1 is soluble in common organic solvents viz., methanol, dichloromethane, chloroform, dimethylformamide and dimethylsulphoxide but insoluble in petroleum ether and diethyl ether. Complex 2 is soluble in dimethylformamide and dimethylsuphoxide, partially soluble in halogenated solvents like dichloromethane, chloroform but insoluble in petroleum ether and diethyl ether. Both the complexes were fully characterised by IR, 1 H NMR, UV–Vis, FAB-MS, electronic and emission spectral studies. Analytical data of the complexes corroborated well to their respective formulations [15]. FAB-MS spectra of both the complexes corresponded well to their formulations (see F-1 and F-2, supporting material). It has been shown that TMT moiety present in aromatic form with covalent metal–sulphur bond displays bands at 1490, 1232 and 879 cm1 [16]. Infrared spectrum of 1 in nujol displayed bands at 1443, 1244 and 888 cm1 whereas corresponding bands in 2 were observed at 1460, 1232,
Fig. 1. ORTEP diagram of 1 (ellipsoids with 50% probability; hydrogen ˚ ) and bond angles atoms are omitted for clarity). Selected bond lengths (A (°) for 1; Rh(1)–N(3) 2.117(5), Rh(1)–Cl(1) 2.4030(17), Rh(1)–S(1) 2.4388(17), Rh(2)–N(1) 2.125(5), Rh(2)–S(2) 2.4581(17), Rh(2)–Cl(2) 2.3915(16), Rh(3)–N(2) 2.123(6), Rh(3)–S(3) 2.4417(18), Rh(3)–Cl(3) 2.391(2), S(1)–C(1) 1.719(6), S(2)–C(2) 1.710(6), S(3)–C(3) 1.695(7), Rh(1)–Cct 1.764, Rh(1)–Cav 2.145, Rh(2)–Cct 1.773, Rh(2)–Cav 2.146, Rh(3)–Cct 1.769, Rh(3)–Cav 2.146, N(3)–Rh(1)–S(1) 67.29(15), N(1)– Rh(2)–S(2) 67.02(14), N(3)–Rh(3)–S(3) 67.28(14), N(3)–Rh(1)–Cl(1) 82.30(15), N(1)–Rh(2)–Cl(2) 86.91(14), N(2)–Rh(3)–Cl(3) 91.39(15), Cl(1)–Rh(1)–S(1) 90.31(6), Cl(2)–Rh(2)–S(2) 90.47(6), Cl(3)–Rh(3)–S(3) 92.98(7).
S Rh
S N
Rh Cl
S
Cl
N N
N
(i)
S
HS
Ru
N N
(ii)
Ph3 P
[1]
(i) [{( η5-C 5Me5 )Rh(μ-Cl)Cl} 2] /Et3N CH 2 Cl2+CH 3 OH(1:1) (ii) [( η 5-C 5H 5)Ru(PPh3 )2Cl] /KOH Absolute Ethanol
Scheme 1.
S
N
N
PPh 3 S
N
SH
Rh Cl
Ru
SH
Ru Ph3P
[2]
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M. Trivedi et al. / Inorganic Chemistry Communications 11 (2008) 526–530
Table 1 Hydrogen bond parameters for 1 D–H A–X a
C(13)–H(13A) Cl(2) C(19)–H(19C) Cl(1)b C(21)–H(21B) Cl(3)c C(29)–H(29C) Cl(2)d C(31)–H(31C) Cl(1)e C(11)–H(11c) C(3) C(11)–H(11A) C(21) C(21)–H(21C) C(7) C(21)–H(21C) C(6) a b c d e
˚) d(H A) (A
˚) D(D A) (A
h(D–H A) (°)
2.78 2.81 2.81 2.73 2.82 2.75 2.85 2.68 2.65
3.692(8) 3.718(9) 3.725(9) 3.680(14) 3.651(8) 3.368 3.555 3.000 3.423
159 157 161 171 146 122 130 158 137
1 x, y, z. x, y, z, 1 x. 1/2 + y, 1/2 z. 1 + x, y, z. x, 1/2 y, 1/2 + z.
the low energy side at 428 nm and 398 nm, respectively. It have been assigned to Mdp!Lp metal to ligand charge transfer transitions (MLCT), while the transitions in the higher energy side at ca. 302–313 nm have been assigned to the intra-ligand p–p* transitions [4,8]. Complexes 1 and 2 were found to be luminescent at ambient temperature in DMSO (see F-4, supporting material). Upon excitation at 313 nm, complex 1 shows weak emission at 380 nm, however excitation at 428 nm (lowest energy MLCT band), emits strongly at 600 nm, this may be attributed to metal to ligand (Rh–L) charge transfer. Similarly, complex 2 upon excitation at 302 nm exhibits broad emission band at 414 nm, but excitation at 398 nm (lowest energy MLCT band), results in emission at 530 nm, which may be attributed to triplet metal-to-ligand charge transfer state (3MLCT) [8,17]. Since,
H3L exhibits emission around 439 nm at room temperature, the observed emissions at 380–414 nm may probably originate from TMT moiety. Crystals of the [{(g5-C5Me5)RhCl}3(l3-L)] (1) suitable for single crystal X-ray diffraction were obtained from CHCl3/diethyl ether by slow diffusion techniques at room temperature [18]. ORTEP depiction of 1 with atom-labels is shown in Fig. 1 and hydrogen bond parameters are listed in Table 1. The TMT ligand in triazenide form is bonded to three rhodium centres using all the three available bis-chelating [N,S] donor sites. Each of the rhodium is coordinated through nitrogen and sulphur atoms of TMT, chloride and Cp* in g5-coordination mode. Considering Cp* as a single coordination site, overall coordination geometry about each rhodium centre is pseudo-tetrahedral or typical piano stool geometry. Average Rh1–Ccp , Rh2–Ccp , Rh3–Ccp distances ˚ ; Rh1–Cct 1.764 A ˚ ), are 2.145 (range 2.133(6)–2.154(7) A ˚ ˚ 2.146 (range 2.125(6)–2.165(7) A; Rh2–Cct 1.773 A) and ˚ (range 2.134(8)–2.157(8) A ˚ ; Rh3–Cct 1.769 A ˚ ), 2.146 A * respectively [19]. The C–C bond lengths within the Cp ring and C–CH3 bond lengths are normal and comparable with those in other Rh–Cp* complexes [20]. The Rh–Cl distance in 1 is normal [Rh(1)–Cl(1) = 2.403(17), Rh(2)–Cl(2) = 2.391(16), Rh(3)–Cl(3) = 2.391(2)] [19]. as the Rh–N bond distances [Rh(1)–N(3) = 2.117(5), Rh(2)–N(1) = 2.125(5), Rh(3)–N(2) = 2.123(6)], which are comparable to Rh–Cl and Rh–N bond distances reported in the literature [19,20]. The angles N–Rh–Cl [N(3)–Rh(1)–Cl(1) = 82.30(15), N(1)–Rh(2)–Cl(2) = 86.91, N(2)–Rh(3)–Cl(3) = 91.39(15)] are normal. The N–Rh–S bite angles are in the range of 67.02(14)–67.29(15)°, which indicates that the bridging
Fig. 2. Double-helical structure in 1 resulting from p–p interaction: (a) wire-frame model and (b) space-filled model.
M. Trivedi et al. / Inorganic Chemistry Communications 11 (2008) 526–530
TMT ligand suffer from a considerable strain [9]. The ˚ [Rh(1)–S(1)], 2.458 A ˚ Rh(III)–S distances are 2.438(17) A ˚ [Rh(2)–S(2)] and 2.441(18) A [Rh(3)–S(3)]. These bond distances are comparable to the one reported in other Rh(III) complexes [21]. Crystal packing in 1 is stabilised by inter- and intramolecular C–H X (X = Cl, p) and p–p interactions. An interesting feature of the crystal packing in 1 is a doublehelical motif (Fig. 2) resulting from p–p interactions. Con˚ tact distances for p–p interactions are 3.36–3.39 A [22a,22b]. C–H Cl type inter- and intra-molecular hydrogen bonds are also present. The C–H Cl contact dis˚ and associated tances are in the range of 2.73–2.82 A angles are in the range 146–159° (see F-5, supporting material). These distances are within the range reported in the literature [22b]. The inter-molecular C–H p weak interactions in 1 results in parallel chain-like structure, in which pentamethylcyclopentadienyl rings are arranged in alternate manner as shown in Fig. 2. Contact distances for ˚ (see C–H p interactions are in the range of 2.66–2.82 A F-6, supporting material). In conclusion, in this work we have presented novel neutral homo-trinuclear rhodium complex [{(g5-C5Me5) RhCl}3(l3-L)] (1) and ruthenium complex [{(g5-C5H5) Ru(PPh3)}3(l3-L)] (2). Coordination of the bridging ligand 2,4,6-trimercapto-1,3,5-triazine in rather rare coordination mode have been established by analytical, spectral and structural studies. To our knowledge complex 1 represents the first example of a structurally characterized trinuclear rhodium complex incorporating 2,4,6-trimercapto-1,3,5triazine as a bridging ligand. Acknowledgements We gratefully acknowledge financial support from council of Scientific and Industrial Research, New Delhi (Senior Research Fellowship to M.T.). We also thank the Head, SAIF, Central Drug Research Institute, Lucknow for analytical and spectral facilities, the Head, Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi and National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka, Japan for extending facilities. Appendix A. Supplementary material CCDC 662727 contains 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. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.inoche.2007.12.039. References [1] (a) P. Gamez, J. Reedijk, Eur. J. Inorg. Chem. (2006) 29; (b) A.M. Churakov, V.A. Tartakovsky, Chem. Rev. 104 (2004) 2601; (c) N. Gimeno, R. Vilar, Coord. Chem. Rev. 250 (2006) 3161.
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(1:1 v/v) (50 ml), chloro-bridged dimeric rhodium complex [{(g5C5Me5) Rh(l-Cl)Cl}2] (0.231 g, 0.37 mmol) and 0.5 ml triethylamine were added. The suspension was stirred at room temperature overnight. Slowly, it gave a clear red solution and finally a dark red coloured compound separated. The red compound thus obtained was filtered, washed with H2O, ethanol, diethyl ether and dried under vacuo. Dark red; Yield: (0.257 g, 70%). Anal. Calc. for C33H45N3S3Cl3Rh3: C, 39.83; H, 4.53; N, 4.23. Found: C, 39.86; H, 4.56; N, 4.03%. IR (cm1, nujol): m = 3450, 2920, 1702, 1637, 1443, 1244, 1154, 1025, 888, 536, 432. 1H NMR (d ppm, 300 MHz, d6DMSO, 298 K): 1.56 (Cp*, s, 45H). FAB-MS: m/z obs. (calcd.), rel. int., assignments: 988 (993), 5 [M+], 958 (957), 60 [MCl]+, 650 (651), 50 [M2Cp*2Cl]+. UV/Vis (nm): kmax (e (dm3 mol1 cm1)) = 428 (36,680), 313 (32,150), 289 (33,110). [{(g5C5H5)Ru(PPh3)}3(l3-L)] (2):To a suspension of 2,4,6-trimercapto1,3,5-triazine (0.044 g, 0.25 mmol) in absolute ethanol (30 ml), KOH (0.042 g, 0.75 mmol) was added and stirred at room temperature for 30.0 min. Slowly it dissolved and gave a clear solution. This solution was treated with [(g5-C5H5)Ru(PPh3)2Cl] (0.546 g, 0.75 mmol) and refluxed overnight under nitrogen atmosphere. The resulting orange red compound was filtered, washed with H2O, ethanol and diethyl ether. Orange red; Yield: (0.765 g, 70%). Anal. Calc. for C72H60N3S3P3Ru3: C, 59.26; H, 4.11; N, 2.88. Found: C, 59.32; H, 4.18; N, 2.86. IR (cm1, nujol): m = 3076, 2950, 1631, 1460, 1232, 1150, 1010, 879, 416. FAB-MS: m/z: obs. (calcd.), rel. int., assignments: 1460 (1458), 40 [M+]; 1195 (1196), 40 [MPPh3]+, 934 (934), 30 [M(PPh3)2]+.1H NMR (d ppm, 300 MHz, CDCl3, 298 K): 7.56 (multiplet, 45H, due to PPh3), 4.70 (s, 15H). UV/Vis (nm): kmax (e (dm3 mol1 cm1)) = 398 (33,570), 302 (34,890). [16] J.R. Bailey, M.J. Hatfield, K.R. Henke, M.K. Krepps, J.L. Otieno, K.D. Simonetti, E.A. Wall, D.A. Atwood, J. Organomet. Chem. 623 (2001) 185. [17] (a) C.-K. Chan, K.-K. Cheung, C.-M. Che, Chem. Commun. (1996) 227; (b) B.K. Santra, M. Menon, C.K. Pal, G.K. Lahiri, J. Chem. Soc., Dalton Trans. (1997) 1387;
[18]
[19]
[20] [21]
[22]
(c) S.K. Singh, M. Chandra, S.K. Dubey, D.S. Pandey, Eur. J. Inorg. Chem. (2006) 3954. X-ray data for 1 was collected on Bruker SMART APEX CCD diffractometer using graphite-monochromated Mo Ka radiation ˚ ) at 293(2) K. The structure was solved by direct (k = 0.71073 A methods and refined by using MAXUS-99 and SHELX-97. Nonhydrogen atoms were refined anisotropically. All the hydrogen atoms were geometrically fixed and allowed to refine using a riding model. Non-hydrogen atoms were refined with anisotropic displacement parameters. [{(g5-C5Me5)RhCl}3(l3-L)], C33H45Cl3N3Rh3S3, M = ˚ , b = 24.2357(15) A ˚, 994.98, Monoclinic, P21/c, a = 12.4740(8) A ˚ , b = 106.2500(10)°, V = 3929.5(4) A ˚ 3, Z = 4, Dc = c = 13.5389(9) A 1.682 g cm3, F(0 0 0) = 1992, T = 293(2) K, R1 = 0.0755, wR2 = 0.2173, GOF = 1.552. A total of 25,070 reflections were collected, 9630 unique (Rint = 0.0280). (a) H. Amouri, C. Guyard-Duhayon, J. Vaissermann, Inorg. Chem. 41 (2002) 1397; (b) T. Scheiring, J. Fiedler, W. Kaim, Organometallics 20 (2001) 1437; (c) H. Aneetha, P.S. Zacharias, B. Srinivas, G.H. Lee, Y. Wong, Polyhedron 18 (1999) 299. P. Paul, B. Tyagi, A.K. Bilakhia, D. Parthsarthi, M.M. Bhadbhade, E. Suresh, G. Ramchandraiah, Inorg. Chem. 37 (1998) 5733. (a) A. Abbasi, M. Habibian, M. Sandstro¨m, Acta Cryst. E 63 (2007) 1904; (b) M.Y. Chavan, X.Q. Lin, M.Q. Ahsan, I. Bernal, J.L. Bear, K.M. Kadish, Inorg. Chem. 25 (1986) 1281; (c) E. Fooladi, T. Graham, M.L. Turner, B. Dalhus, P.M. Maitlis, M. Tilset, Dalton Trans. (2002) 975; (d) J.A. Camerano, M.A. Casado, M.A. Ciriano, C. Tejel, L.A. Oro, Dalton Trans. (2005) 3092; (e) M. Doux, N. Me´zailles, L. Ricard, P. Le Floch, P. Adkine, T. Berclaz, M. Geoffroy, Inorg. Chem. 44 (2005) 1147. (a) G.R. Desiraju, Angew. Chem. Int. Ed. Engl. 34 (1995) 2311; (b) G.R. Desiraju, T. Steiner, The Weak Hydrogen Bond in Structural Chemistry and Biology, Oxford University Press, Oxford, 1999.