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Ruthenium(VI) and osmium(VI) nitrido complexes with halogenated phenoxide and thiophenoxide ligands
Inorganica Chimica Acta 362 (2009) 5190–5194
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Ruthenium(VI) and osmium(VI) nitrido complexes with halogenated phenoxide and thiophenoxide ligands Ngai-Man Lam a, Xiao-Yi Yi a, Chun-Sing Lai a, Wai-Man Cheung a, Qian-Feng Zhang b, Ian D. Williams a, Wa-Hung Leung a,* a b
Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR China Department of Applied Chemistry, Anhui University of Technology, Ma’anshan, Anhui 243002, PR China
a r t i c l e
i n f o
Article history: Received 12 May 2009 Received in revised form 27 August 2009 Accepted 11 September 2009 Available online 16 September 2009 Keywords: Ruthenium Osmium Nitrido Phenoxide Thiophenoxide
a b s t r a c t Treatment of [Bun4N][Ru(N)Cl4] with Na(OR) afforded [Bun4N][Ru(N)(OR)4] (R = C6F5 (1), C6F4H (2), C6Br5 (3)), whereas that with [Bun4N][Os(N)Cl4] gave [Bun4N][Os(N)(OR)3Cl] (R = C6F5 (4), C6F4H (5), C6Br5 (6)). Treatment of [Bun4N][M(N)Cl4] with Na(SC6F4H) and Na(Sxyl) (xyl = 2,6-dimethylphenyl) afforded [Bun4N][M(N)(SC6F4H)4] (M = Ru (7), Os (8)) and [Bun4N][M(N)(Sxyl)4] (M = Ru (9), Os (10)), respectively. The crystal structures of compounds 1, 6 and 9 have been determined. Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction Transition-metal nitrido compounds have attracted much attention due to their possible involvements in metal-mediated nitrogen atom transfer reactions and nitrogen fixation [1–4]. There is an increasing interest in nitrido compounds of late transitionmetals that are known to exhibit electrophilic behavior [5–18]. In particular, reactions of electrophilic Os(VI) nitrido complexes containing N-donor ligands such as polypyridyl and hydridotris(pyrazolyl)borate with nucleophiles, including amine N-oxides, secondary amines, azide, cyanide, BPh3, and thiols have been studied extensively [11–14]. Recently, Lau and coworkers demonstrated that Ru(VI) nitrido compounds with salen ligands are considerably more reactive than the Os(VI) congeners [15]. In donor solvents or in the presence of Lewis bases, [Ru(salen)(N)]+ complexes undergo facile bimolecular N N coupling to give Ru(III) species and N2 [16]. In the presence of pyridine, Ru(VI) nitrido complexes reacted with alkenes to give Ru(IV) complexes with deprotonated aziridine ligands [17]. This prompted us to explore the chemistry of Ru(VI) nitrido complexes containing electronwithdrawing halogenated phenoxide and thiophenoxide ligands. The most common Ru(VI) nitrido complexes are those containing halide, nitrogen, carbon and sulfur donor ligands [19]. Although Ru(VI) nitrido complexes with chelating alkoxide and phenoxide li* Corresponding author. Tel.: +852 2358 7360; fax: +852 2358 1594. E-mail address: [email protected] (W.-H. Leung). 0020-1693/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.ica.2009.09.029
gands are well documented [20–23], to our knowledge, Ru(VI) complexes with simple phenoxide ligands have not been isolated. Our interest in high-valent Ru halogenated phenoxide complexes is also stimulated by a report that Ru(IV) alkylidene pentafluorophenoxide complexes are active catalysts for alkene metathesis [24]. Herein, we describe the synthesis and structures of Ru(VI) and Os(VI) nitrido compounds with halogenated phenoxide and thiophenoxide ligands.
2. Experimental 2.1. General All manipulations were carried out under nitrogen by standard Schlenk techniques. Solvents were purified by standard procedures and distilled prior to use. NMR spectra were recorded on a Varian Mercury 300 spectrometer operating at 300, 282.5 and 121.5 MHz for 1H, 19F and 31P, respectively. Chemical shifts (d, ppm) were reported with reference to SiMe4 (1H), CF3C6H5 (19F) and H3PO4 (31P). Infrared spectra (KBr) were recorded on a Perkin–Elmer 16 PC FTIR spectrophotometer. Elemental analyses were performed by Medac Ltd., Surrey, UK. The compounds [Bun4N][M(N)Cl4] (M = Ru, Os) were prepared according to literature methods [25,26]. Pentafluorophenol, pentabromophenol, 2,3,5,6-tetrafluorophenol, 2,3,5,6-tetrafluorothiophenol, and 2,6-dimethylthiophenol were purchased from
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Aldrich Ltd. and used as received. Sodium salts of halogenated phenols and thiophenols were prepared by reaction of sodium hydride with halogenated phenols and thiophenols, respectively, in tetrahydrofuran (THF). 2.2. Synthesis of complexes 2.2.1. [Bun4N][Ru(N)(OR)4] (R = C6F5 (1), C6F4H (2), C6Br5 (3)) A mixture of [Bun4N][Ru(N)Cl4] (100 mg, 0.2 mmol) and Na(OR) (0.8 mmol) in THF (25 mL) was stirred at room temperature overnight. The solvent of filtrate was removed in vacuo and the residue was washed with hexane and Et2O. The solid crude product was recrystallized from THF–Et2O–hexane to afford crystals or crystalline solid. Compound 1: Orange-yellow crystals. Yield: 80 mg (37%). 1H NMR (CDCl3): d 3.45 (m, 8H, CH3CH2CH2CH2), 1.84 (m, 8H, CH3CH2CH2CH2), 1.46 (m, 8H, CH3CH2CH2CH2), 1.02 (t, 12H, CH3CH2CH2CH2). 19F {1H} NMR (CDCl3): d 157.4, 168.1, 170.2. Anal. Calc. for C40H36F20N2O4Ru: C, 44.1; H, 3.33; N, 2.57. Found: C, 44.6; H, 3.51; N, 2.71%. Compound 2: Orange crystalline solid. Yield: 79 mg (39%). 1H NMR (CDCl3): d 6.79 (m, 4H, OC6F4H), 3.32 (m, 8H, CH3CH2CH2CH2), 1.84 (m, 8H, CH3CH2CH2CH2), 1.44 (m, 8H, CH3CH2CH2CH2), 0.99 (t, 12H, CH3CH2CH2CH2). 19F {1H} NMR (CDCl3): d 145.8, 157.8 ppm. Anal. Calc. for C40H40F16N2O4Ru: C, 47.2; H, 3.96; N, 2.75. Found: C, 47.0; H, 4.66; N, 2.71%. Compound 3: Orange-red crystalline solid. Yield: 166 mg (36%). 1 H NMR (CDCl3): d 3.60 (m, 8H, CH3CH2CH2CH2), 1.43 (m, 8H, CH3CH2CH2CH2), 1.10 (m, 8H, CH3CH2CH2CH2), 1.05 (t, 12H, CH3CH2CH2CH2). Anal. Calcd. for C40H36Br20N2O4Ru: C, 20.8; H, 1.57; N, 1.21. Found: C, 20.2; H, 1.90; N, 1.20%. 2.2.2. [Bun4N][Os(N)(OR)3Cl] (R = C6F5 (4), C6F4H (5), C6Br5 (6)) A mixture of [Bun4N][Os(N)Cl4] (100 mg, 0.17 mmol) and Na(OR) (0.51 mmol) in THF (25 mL) was stirred at room temperature overnight. The solvent of filtrate was removed in vacuo and the residue was washed with hexane and Et2O. The crude product was recrystallized from THF–Et2O–hexane to afford crystals or crystalline solid. Compound 4: Yellow solid. Yield: 75 mg (43%). 1H NMR (CDCl3): d 3.15 (m, 8H, CH3CH2CH2CH2), 1.60 (m, 8H, CH3CH2CH2CH2), 1.41 (m, 8H, CH3CH2CH2CH2), 0.99 (t, 12H, CH3CH2CH2CH2). 19F {1H} NMR (CDCl3): d 157.8, 158.1, 158.6, 164.6, 167.7, 168.2. Anal. Calc. for C34H36ClF15N2O3Os: C, 35.60; H, 3.52; N, 2.72. Found: C, 36.20; H, 3.45; N, 2.83%. Compound 5: Yellow solid. Yield: 75 mg (45%). 1H NMR (CDCl3): d 6.61 (m, 3H, OC6F4H), 3.45 (m, 8H, CH3CH2CH2CH2), 1.88 (m, 8H, CH3CH2CH2CH2), 2.98 (m, 8H, CH3CH2CH2CH2), 0.98 (t, 12H, CH3CH2CH2CH2). 19F {1H} NMR (CDCl3): d 142.4, 144.4, 156.8, 157.9, 162.9. Anal. Calc. for C34H39ClF12N2O3Os: C, 41.8; H, 4.02; N, 2.87. Found: C, 41.7; H, 4.10; N, 3.00%. Compound 6: Red crystals. Yield: 76 mg (23%). 1H NMR (CDCl3): d 3.32 (m, 8H, CH3CH2CH2CH2), 1.84 (m, 8H, CH3CH2CH2CH2), 1.44 (m, 8H, CH3CH2CH2CH2), 0.99 (t, 12H, CH3CH2CH2CH2). Anal. Calc. for C34H36Br15ClN2O3Os: C, 21.0; H, 1.87; N, 1.44. Found: C, 21.8; H, 2.00; N, 1.40%. 2.2.3. [Bun4N][M(N)(SC6F4H)4] (M = Ru (7), Os (8)) A mixture of [Bun4N][M(N)Cl4] (100 mg; M = Ru (0.2 mmol), Os (0.17 mmol)) and Na(SC6F4H) in THF (25 mL) was stirred at room temperature overnight. The solvent of filtrate was removed in vacuo and the residue was washed with hexane and Et2O. The solid crude product was recrystallized from CH2Cl2–hexane or THF– Et2O–hexane to afford crystalline solid. Compound 7: Orange-yellow solid. Yield: 82 mg (38%). 1H NMR (CDCl3): d 7.24 (m, 4H, SC6F4H), 3.67 (m, 8H, CH3CH2CH2CH2), 1.82
(m, 8H, CH3CH2CH2CH2), 1.43 (m, 8H, CH3CH2CH2CH2), 0.98 (t, 12H, CH3CH2CH2CH2). 19F {1H} NMR (CDCl3): d 131.3, 142.6. Anal. Calc. for C40H40F16N2S4Ru: C, 44.4; H, 3.73; N, 2.59. Found: C, 43.0; H, 4.60; N, 2.80%. Compound 8: Yellow solid. Yield: 70 mg (35%). 1H NMR (CDCl3): d 7.34 (m, 4H, SC6F4H), 3.16 (m, 8H, CH3CH2CH2CH2), 1.85 (m, 8H, CH3CH2CH2CH2), 1.44 (m, 8H, CH3CH2CH2CH2), 0.99 (t, 12H, CH3CH2CH2CH2). 19F {1H} NMR (CDCl3): d 132.1, 142.6. Anal. Calc. for C40H40F16N2OsS4?2CH2Cl2: C, 37.6; H, 3.31; N, 2.09. Found: C, 37.7; H, 3.21; N, 1.97%. 2.2.4. [Bun4N][M(N)(Sxyl)4] (xyl = 2,6-dimethylphenyl; M = Ru (9), Os(10)) A mixture of [Bun4N][M(N)Cl4] (M = Ru; 100 mg, 0.2 mmol, M = Os; 100 mg, 0.17 mmol) and Na(Sxyl) in THF (25 mL) was stirred at room temperature overnight. The solvent of filtrate was removed in vacuo and the residue was washed with hexane and Et2O. The solid crude product was recrystallized from CH2Cl2–hexane or THF–Et2O–hexane to afford crystals or crystalline solid. Compound 9: Orange crystals. Yield: 85 mg (47%). 1H NMR (CDCl3): d 6.85 (m, 12H, phenyl), 3.46 (m, 8H, CH3CH2CH2CH2), 2.71 (s, 24H, Me), 1.85 (m, 8H, CH3CH2CH2CH2), 1.60 (m, 8H, CH3CH2CH2CH2), 0.98 (t, 12H, CH3CH2CH2CH2) ppm. Anal. Calc. for C48H72N2RuS4?CH2Cl2: C, 59.4; H, 7.52; N, 2.83. Found: C, 59.5; H, 7.70; N, 2.70%. Compound 10: Yellow solid. Yield: 83 mg (49%). 1H NMR (CDCl3): d 6.83 (m, 12H, phenyl), 3.62 (m, 8H, CH3CH2CH2CH2), 2.82 (s, 24H, Me), 1.81 (m, 8H, CH3CH2CH2CH2), 1.43 (m, 8H, CH3CH2CH2CH2), 0.99 (t, 12H, CH3CH2CH2CH2). Anal. Calc. for C48H72N2OsS4?CH2Cl2: C, 54.5; H, 6.90; N, 2.59. Found: C, 54.1; H, 7.02; N, 2.50%. 2.3. X-ray crystallography Complexes 1, 6, and 9THF have been characterized by X-ray diffraction studies. Intensity data were collected on a Bruker SMART
Table 1 Crystallographic data and experimental details for [Bun4N][Ru(N)(OC6F5)4] (1), [Bun4N][Os(N)(OC6Br5)3Cl] (6), and [Bun4N][Ru(N)(Sxyl)4] THF (9THF).
Formula Formula weight a (Å) b (Å) c (Å) a (o) b (o) c (o) V (Å3) Z Crystal system Space group Dcalc (g cm3) T (K) l (mm1) F(0 0 0) Number of reflections Number of independent reflections Rint R1, wR2 (I > 2r(I)) R1, wR2 (all data) Goodness-of-fit (GOF)a a
1
6
9THF
C40H36F20N2O4Ru 1089.78 10.0983(7) 23.3803(17) 18.5893(14) 90 90.9850(10) 90 4388.3(6) 4 monoclinic C2/c 1.649 173(2) 0.485 2184 13 987
C33H34Br15ClN2O3Os 1930.92 16.5100(11) 18.4444(13) 19.0686(13) 90 111.7590(10 90 5393.0(6) 4 monoclinic P21/n 2.378 173(2) 13.559 3552 38 629
C52H80N2ORuS4 978.49 11.7144(13) 15.1225(16) 15.2081(16) 89.812(2) 83.824(2) 74.508(2) 2580.3(5) 2 triclinic P1 1.259 100(2) 0.503 1044 12 806
3733
11 619
8723
0.0246 0.0356, 0.0876
0.0426 0.0454, 0.1025
0.0504 0.0551, 0.0898
0.042, 0.090
0.0869, 0.1127
0.1061, 0.1008
1.033
0.951
0.974
GoF = [(Rw|Fo| |Fc|)2/(Nobs Nparam)]½.
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Table 2 Selected bond lengths (Å) and angles (o) for 1. Ru(1A)–N(1) Ru(1A)–O(1)#1 Ru(1A)–O(1)
1.568(4) 1.980(2) 1.980(2)
Ru(1A)–O(2)#1 Ru(1A)–O(2)
1.980(2) 1.980(2)
N(1)–Ru(1A)–O(1)#1 N(1)–Ru(1A)–O(1) O(1)#1–Ru(1A)–O(1) N(1)–Ru(1A)–O(2)#1 O(1)#1–Ru(1A)–O(2)#1
106.69(6) 106.69(6) 146.62(12) 108.98(6) 84.82(7)
O(1)–Ru(1A)–O(2)#1 N(1)–Ru(1A)–O(2) O(1)#1–Ru(1A)–O(2) O(1)–Ru(1A)–O(2) O(2)#1–Ru(1A)–O(2)
84.46(7) 108.98(6) 84.46(7) 84.82(7) 142.05(12)
Symmetry transformations used to generate equivalent atoms: #1 x + 1, y, z + 3/ 2.
Table 3 Selected bond lengths (Å) and angles (o) for 6. Os(1)–N(1) Os(1)–O(1) Os(1)–O(3)
1.611(6) 1.974(4) 1.976(4)
Os(1)–O(2) Os(1)–Cl(1)
1.987(4) 2.2901(16)
N(1)–Os(1)–O(1) N(1)–Os(1)–O(3) O(1)–Os(1)–O(3) N(1)–Os(1)–O(2) O(1)–Os(1)–O(2)
106.6(2) 106.2(2) 146.50(18) 106.1(2) 84.74(17)
O(3)–Os(1)–O(2) N(1)–Os(1)–Cl(1) O(1)–Os(1)–Cl(1) O(3)–Os(1)–Cl(1) O(2)–Os(1)–Cl(1)
79.69(17) 102.3(2) 90.41(13) 89.34(12) 151.37(13)
APEX 1000 CCD diffractometer using graphite-monochromated Mo Ka radiation (k = 0.71073 Å). The collected frames were processed with the software SAINT [27]. Structures were solved by the direct methods and refined by full-matrix least-squares on F2 using the SHELXTL software package [28]. Atomic positions of non-hydrogen atoms were refined with anisotropic parameters and with suitable restraints except the co-crystallized THF molecule in 9. Hydrogen atoms were generated geometrically and allowed to ride on their respective parent carbon atoms before the final cycle of leastsquares refinement. Crystallographic data and experimental details for compounds 1, 6, and 9THF are listed in Table 1. Selected bond distances and angles of these compounds are listed in Table 2–4 and their structures are shown in Figs. 2–4, respectively. In complex 1, the disordered ruthenium atom was split into two sites, Ru1A and Ru1B, with occupancy of 0.98 and 0.02, respectively. In complex 6, the bromine atoms Br13, Br14, Br15 in the C11–C12–C13–C14–C15–C16 phenyl rings and Br33 and Br34 in the C31–C32–C33–C34–C35–C36 phenyl ring were found to be disorder. Each of these bromine atoms were split into two sites with occupancy of 0.5 each. In complex 9, the disordered Ru and N atoms were split into two sites (Ru1 and Ru1A and N1 and N1A) with occupancies of 0.9 and 0.1, respectively. Also, the co-crystallized THF molecule was 50:50 disordered.
3. Results and discussion Table 4 Selected bond lengths (Å) and angles (o) for 9THF.
3.1. Halogenated phenoxide compounds
Ru(1)–N(1) Ru(1)–S(2) Ru(1)–S(4)
1.615(4) 2.3547(11) 2.3571(12)
Ru(1)–S(1) Ru(1)–S(3)
2.3641(11) 2.3672(12)
N(1)–Ru(1)–S(2) N(1)–Ru(1)–S(4) S(2)–Ru(1)–S(4) N(1)–Ru(1)–S(1) S(2)–Ru(1)–S(1)
108.52(13) 107.49(13) 143.97(5) 106.24(13) 84.23(4)
S(4)–Ru(1)–S(1) N(1)–Ru(1)–S(3) S(2)–Ru(1)–S(3) S(4)–Ru(1)–S(3) S(1)–Ru(1)–S(3)
84.89(4) 106.37(13) 85.72(4) 85.23(4) 147.38(5)
The syntheses of Ru(VI) and Os(VI) nitrido complexes with halogenated phenoxide ligands are summarized in Scheme 1. Treatment of [Bun4N][Ru(N)Cl4] with Na(OR) afforded the tetraphenoxide complexes [Bun4N][Ru(N)(OR)4] (R = C6F5 (1), C6F4H (2), C6Br5 (3)), which could be isolated as air-stable orange crystals in 36–39% yield. Although NMR spectroscopy indicated that the reaction between [Bun4N][Ru(N)Cl4] with Na(OR) is clean,
Fig. 1. 1H NMR spectrum (300 MHz, 298 K) of 2 in CD3CN solution.
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complexes 1–3 are not isolated in high yields mainly because of difficulty in crystallization. To our knowledge, these are the first isolated Ru(VI) nitrido complexes with halogenated phenoxide ligands. Compounds 1–3 are soluble in CH2Cl2 and polar solvents such as acetone, but insoluble in Et2O and hexane. It should be noted that the halogen substituents of the phenoxide ligands is essential for the isolation of Ru(VI) nitrido phenoxide complexes. Reaction of [Bun4N][Ru(N)Cl4] with non-halogenated phenoxides, e.g. sodium phenoxide and sodium 2,6-dimethylphenoxide, resulted in intractable materials that did not crystallize. In the 1H NMR spectrum of 2, the phenyl protons (C6F4H) appeared as a multiplet at d 6.79 ppm in CDCl3 and d 7.25 ppm in CD3CN (Fig. 1). The 19 F NMR spectrum of 1 displayed three resonances at d 157.4, 168.1 and 170.2 ppm, whereas two doublets at d 145.8 and 157.8 ppm were observed for 2. Unlike the Ru(salen) nitrido complexes [16], complexes 1–3 are stable in donor solvents such as acetonitrile. No bimolecular N N coupling reaction was found. They reacted readily with PPh3 to give Ph3P = N = PPh3+ characterized by 31P NMR spectroscopy (d 22 ppm) along with paramagnetic species, possibly Ru(III) complexes, which have yet been characterized. A similar reaction involving an Os(VI) nitrido complex, [Os(tpy)Cl2(N)]+ (tpy = 2,20 :60 ,200 -terpyridine), has been reported [29]. Treatment of [Bun4N][Os(N)Cl4] with four equivalents of Na(OR) led to isolation of the triphenoxide complexes [Bun4N][Os(N)(OR)3Cl] (R = C6F5 (4), C6F4H (5), C6Br5 (6)) along with uncharacterized side-products, possibly the tetraphenoxide complex. The yields of the triphenoxide complexes were optimized when 3 equivalents of the phenoxide were employed. Complexes 4–6 are air stable in both the solid state and solutions. In the 1H NMR spectrum of 5 in CDCl3, the phenyl protons of the tetrafluorophenoxide ligands of appeared as an unresolved multiplet at d 6.61 ppm.
Fig. 2. Thermal ellipsoid plot (50% probability level) of the complex anion in 1.
M = Ru
[Bun4N]
Ru
[Bun4N][M(N)Cl4]
OR OR
RO
R = C6F5 (1) = C6F4H (2) = C6Br5 (3)
Na(OR)
3.2. Thiophenoxide compounds Treatment of [Bun4N][M(N)Cl4] with NaSC6F4H led to isolation of air-stable red solids characterized as [Bun4N][M(N)(SC6F4H)4] (M = Ru (7), Os (8)) (Scheme 2). Unlike the phenoxide analogues, Ru(VI) and Os(VI) nitrido complexes with non-halogenated thiophenoxide ligands could also be synthesized. Thus, treatment of [Bun4N][M(N)Cl4] with NaSxyl (xyl = 2,6-dimethylphenyl) afforded [Bun4N][M(N)(Sxyl)4] (M = Ru (9), Os (10)). The resonances of the phenyl proton in 7 and 8 were observed as multiplets at d 7.24 and 7.34 ppm, respectively, which are more downfield than those of the phenoxide analogues 2 and 5. The 1H NMR spectra of 9 and 10 displayed a singlet at d 2.71 and 2.82 ppm, respectively, which are attributable to the magnetically equivalent methyl protons.
N RO
M = Os
[Bun4N]
N RO RO
Os
Cl OR
R = C6F5 (4) = C6F4H (5) = C6Br5 (6) Scheme 1.
3.3. Crystal structures Compounds 1, 6, and 9THF have been characterized by X-ray diffraction studies. Fig. 2 shows the structure of the complex anion in 1. The geometry around Ru atom is pseudo square pyramidal with the nitrido group at the apical position. The Ru is displaced above the mean O4 plane by ca. 0.606 Å that is comparable to that in [Ru(N)(cat)2] (cat2 = catecholate) (0.62 Å) [22]. The Ru–N distance of 1.568(4) Å is typical for Ru(VI) nitrido compounds and compares well with that in [AsPh4][Ru(N)Br4] (1.578 Å) [30] but is slightly shorter than that for [Bun4N][Ru(N)(cat)2] (1.603(4) Å) [22]. The Ru–O distances (1.980(2) Å) are longer than those in [Bun4N][Ru(N)(cat)2] (1.954(3)–1.962(2) Å) [22]. The rather large Ru–O–C angles (120.8(2)–125.6(2)o) are indicative of Ru–O p interactions. The structure of complex 6 is similar to that of 1 with the nitrido group at the apical position (Fig. 3). The Os is displaced above the O3Cl plane by ca. 0.540 Å. The Os–N distance of 1.611(6) Å is slightly shorter than that in [Bun4N][Os(N)(cat)2] (1.641(8) Å), whereas the Os–O distances (av. 1.976 Å) are comparable to those
Fig. 3. Thermal ellipsoid plot (50% probability level) of the complex anion in 6.
in [Bun4N][Os(N)(cat)2] (av. 1.971 Å) [22]. The Os–O–C angles in the range of 124.6(3)–127.9(3)o are slightly larger than those in 1. The
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Council (Project No.: 602104) is gratefully acknowledged. Q.-F. Zhang thanks the Program for New Century Excellent Talents in University of China (NCET-06-0556) for support. Appendix A. Supplementary material CCDC 724305, 724306, and 724307 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. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.ica.2009.09.029. References
Fig. 4. Thermal ellipsoid plot (50% probability level) of the complex anion in 9. All hydrogen atoms are omitted for clarity.
[Bun4N][M(N)Cl4]
Na(SR)
[Bun4N]
N RS RS
M
SR SR
R = C6F4H, M = Ru (7) R = C6F4H, M = Os (8) R = 2,6-Me2C6H3, M = Ru (9) R = 2,6-Me2C6H3, M = Os (10) Scheme 2.
Os-Cl distance of 2.290(2) Å is comparable to that in [Ph4P][OsNCl4] (2.3099 (4) Å) [31]. In complex 9THF, the geometry around Ru is pseudo square planar with the nitrido group at the apical position (Fig. 4). The Ru is displaced above the mean S4 plane by ca. 0.696 Å that is comparable to that in [Ru(N)(bdt)2] (bdt2 = benzene-1,2-dithiolate) (0.69 Å). The Ru–N distance of 1.615(4) Å is slightly longer than that in 1, but compares well with that of [Ru(N)(bdt)2] (1.613(5) Å). The Ru–S distances (2.355(1)–2.367(1) Å) in 9 are similar to that in [Ru(N)(bdt)2] (2.317(2)–2.330(2) Å) [32]. The Ru–S–C angles (111.7(1)–112.1(1)o) are smaller than the Ru–O–C angles in 1. 4. Conclusions We have synthesized and structurally characterized Ru(VI) and Os(VI) nitrido complexes with halogenated phenoxide ligands. It was found that the halogen substituents of the phenoxide ligands are important for the synthesis of Ru(VI) nitrido phenoxide complexes. We have also synthesized Ru(VI) and Os(VI) nitrido complexes with tetrafluorothiophenoxide and 2,6-dimethylthiophenoxide ligands. Acknowledgements We thank Dr. Herman H.Y. Sung for solving the crystal structures. The financial support from the Hong Kong Research Grants
[1] J.T. Groves, T. Takahashi, J. Am. Chem. Soc. 105 (1983) 2073. [2] J.D. Bois, C.S. Tomooka, J. Hong, E.M. Carreira, Acc. Chem. Res. 30 (1997) 364. and references cited therein. [3] S.K.-Y. Leung, J.-S. Huang, J.-L. Liang, C.-M. Che, Z.-Y. Zhou, Angew. Chem., Int. Ed. 42 (2003) 340. [4] R.R. Schrock, Angew. Chem., Int. Ed. 47 (2008) 5512. [5] W.A. Nugent, J.M. Mayer, Metal-Ligand Multiple Bonds, John Wiley and Sons, Now York, 1988. [6] J.F. Berry, Comment Inorg. Chem. 30 (2009) 28. [7] T.J. Meyer, M.H.V. Huynh, Inorg. Chem. 42 (2003) 8140. and references cited therein. [8] M.H.V. Huynh, E.-S. El-Samanody, P.S. White, T.J. Meyer, Inorg. Chem. 38 (1999) 3760. [9] M.H.V. Huynh, E.-S. El-Samanody, K.D. Demadis, P.S. White, T.J. Meyer, Inorg. Chem. 39 (2000) 3075. [10] M.H.V. Huynh, R.T. Baker, D.E. Morris, P.S. White, T.J. Meyer, Angew. Chem., Int. Ed. 41 (2002) 3870. [11] T.J. Crevier, B.K. Bennett, J.D. Soper, J.A. Bowman, A. Dehestani, D.A. Hrovat, S. Lovell, W. Kaminsky, J.M. Mayer, J. Am. Chem. Soc. 123 (2001) 1059. [12] T.J. Crevier, J.M. Mayer, Angew. Chem., Int. Ed. 37 (1998) 1891. [13] T.J. Crevier, J.M. Mayer, J. Am. Chem. Soc. 120 (1998) 5595. [14] T.J. Crevier, S. Lovell, J.M. Mayer, A.L. Rheingold, I.A. Guzei, J. Am. Chem. Soc. 120 (1998) 6607. [15] T.-W. Wong, T.-C. Lau, W.-T. Wong, Inorg. Chem. 38 (1999) 6181. [16] W.-L. Man, T.-M. Tang, T.-W. Wong, T.-C. Lau, S.-M. Peng, W.-T. Wong, J. Am. Chem. Soc. 126 (2004) 478. [17] W.-L. Man, W.W.Y. Lam, S.-M. Yiu, T.-C. Lau, S.-M. Peng, J. Am. Chem. Soc. 126 (2004) 15336. [18] X.-Y. Yi, T.C.H. Lam, Y.-K. Sau, Q.-F. Zhang, I.D. Williams, W.-H. Leung, Inorg. Chem. 46 (2007) 7193. [19] C.-M. Che, T.-C. Lau, in: J.A. McCleverty, T.J. Meyer (Eds.), Comprehensive Coordination Chemistry II, vol. 5, Elsevier Pergamon, Amsterdam, p. 733. [20] K.-L. Yip, W.-Y. Yu, P.-M. Chan, N.-Y. Zhu, C.-M. Che, Dalton Trans. (2003) 3556. [21] P.-M. Chan, W.-Y. Yu, C.-M. Che, K.-K. Cheung, J. Chem. Soc., Dalton Trans. (1998) 3183. [22] G.-S. Fang, J.-S. Huang, N.-Y. Zhu, C.-M. Che, Eur. J. Inorg. Chem. (2004) 1341. [23] J.J. Schwab, E.C. Wilkinson, S.R. Wilson, P.A. Shapley, J. Am. Chem. Soc. 113 (1991) 6124. [24] J.C. Conrad, H.H. Parnas, J.L. Snelgrove, D.E. Fogg, J. Am. Chem. Soc. 127 (2005) 11882. [25] W.P. Griffith, D. Pawson, J. Chem. Soc., Dalton Trans. (1973) 1315. [26] W.P. Griffith, D. Pawson, J. Chem. Soc., Dalton Trans. (1975) 417. [27] Bruker SMART and SAINT+, Version 6.02a, Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA, 1998. [28] G.M. Sheldrick, SHELXTL-Plus V5.1 Software Reference Manual, Bruker AXS Inc., Madison, Wisconsin, USA, 1997. [29] K.D. Demadis, M. Bakir, B.G. Klesczewski, D.S. Williams, P.S. White, T.J. Meyer, Inorg. Chim. Acta 270 (1998) 511. [30] D. Collison, D.D. Garner, F.E. Mabbs, T.J. Kong, J. Chem. Soc., Dalton Trans. (1981) 1820. [31] F.L. Phillips, A.C. Skapski, J. Cryst. Mol. Struct. 5 (1975) 83. [32] D. Sellmann, M.W. Wemple, W. Donaubauer, F.W. Heinemann, Inorg. Chem. 36 (1997) 1397.
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Inorganica Chimica Acta journal homepage: www.elsevier.com/locate/ica
Ruthenium(VI) and osmium(VI) nitrido complexes with halogenated phenoxide and thiophenoxide ligands Ngai-Man Lam a, Xiao-Yi Yi a, Chun-Sing Lai a, Wai-Man Cheung a, Qian-Feng Zhang b, Ian D. Williams a, Wa-Hung Leung a,* a b
Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR China Department of Applied Chemistry, Anhui University of Technology, Ma’anshan, Anhui 243002, PR China
a r t i c l e
i n f o
Article history: Received 12 May 2009 Received in revised form 27 August 2009 Accepted 11 September 2009 Available online 16 September 2009 Keywords: Ruthenium Osmium Nitrido Phenoxide Thiophenoxide
a b s t r a c t Treatment of [Bun4N][Ru(N)Cl4] with Na(OR) afforded [Bun4N][Ru(N)(OR)4] (R = C6F5 (1), C6F4H (2), C6Br5 (3)), whereas that with [Bun4N][Os(N)Cl4] gave [Bun4N][Os(N)(OR)3Cl] (R = C6F5 (4), C6F4H (5), C6Br5 (6)). Treatment of [Bun4N][M(N)Cl4] with Na(SC6F4H) and Na(Sxyl) (xyl = 2,6-dimethylphenyl) afforded [Bun4N][M(N)(SC6F4H)4] (M = Ru (7), Os (8)) and [Bun4N][M(N)(Sxyl)4] (M = Ru (9), Os (10)), respectively. The crystal structures of compounds 1, 6 and 9 have been determined. Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction Transition-metal nitrido compounds have attracted much attention due to their possible involvements in metal-mediated nitrogen atom transfer reactions and nitrogen fixation [1–4]. There is an increasing interest in nitrido compounds of late transitionmetals that are known to exhibit electrophilic behavior [5–18]. In particular, reactions of electrophilic Os(VI) nitrido complexes containing N-donor ligands such as polypyridyl and hydridotris(pyrazolyl)borate with nucleophiles, including amine N-oxides, secondary amines, azide, cyanide, BPh3, and thiols have been studied extensively [11–14]. Recently, Lau and coworkers demonstrated that Ru(VI) nitrido compounds with salen ligands are considerably more reactive than the Os(VI) congeners [15]. In donor solvents or in the presence of Lewis bases, [Ru(salen)(N)]+ complexes undergo facile bimolecular N N coupling to give Ru(III) species and N2 [16]. In the presence of pyridine, Ru(VI) nitrido complexes reacted with alkenes to give Ru(IV) complexes with deprotonated aziridine ligands [17]. This prompted us to explore the chemistry of Ru(VI) nitrido complexes containing electronwithdrawing halogenated phenoxide and thiophenoxide ligands. The most common Ru(VI) nitrido complexes are those containing halide, nitrogen, carbon and sulfur donor ligands [19]. Although Ru(VI) nitrido complexes with chelating alkoxide and phenoxide li* Corresponding author. Tel.: +852 2358 7360; fax: +852 2358 1594. E-mail address: [email protected] (W.-H. Leung). 0020-1693/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.ica.2009.09.029
gands are well documented [20–23], to our knowledge, Ru(VI) complexes with simple phenoxide ligands have not been isolated. Our interest in high-valent Ru halogenated phenoxide complexes is also stimulated by a report that Ru(IV) alkylidene pentafluorophenoxide complexes are active catalysts for alkene metathesis [24]. Herein, we describe the synthesis and structures of Ru(VI) and Os(VI) nitrido compounds with halogenated phenoxide and thiophenoxide ligands.
2. Experimental 2.1. General All manipulations were carried out under nitrogen by standard Schlenk techniques. Solvents were purified by standard procedures and distilled prior to use. NMR spectra were recorded on a Varian Mercury 300 spectrometer operating at 300, 282.5 and 121.5 MHz for 1H, 19F and 31P, respectively. Chemical shifts (d, ppm) were reported with reference to SiMe4 (1H), CF3C6H5 (19F) and H3PO4 (31P). Infrared spectra (KBr) were recorded on a Perkin–Elmer 16 PC FTIR spectrophotometer. Elemental analyses were performed by Medac Ltd., Surrey, UK. The compounds [Bun4N][M(N)Cl4] (M = Ru, Os) were prepared according to literature methods [25,26]. Pentafluorophenol, pentabromophenol, 2,3,5,6-tetrafluorophenol, 2,3,5,6-tetrafluorothiophenol, and 2,6-dimethylthiophenol were purchased from
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Aldrich Ltd. and used as received. Sodium salts of halogenated phenols and thiophenols were prepared by reaction of sodium hydride with halogenated phenols and thiophenols, respectively, in tetrahydrofuran (THF). 2.2. Synthesis of complexes 2.2.1. [Bun4N][Ru(N)(OR)4] (R = C6F5 (1), C6F4H (2), C6Br5 (3)) A mixture of [Bun4N][Ru(N)Cl4] (100 mg, 0.2 mmol) and Na(OR) (0.8 mmol) in THF (25 mL) was stirred at room temperature overnight. The solvent of filtrate was removed in vacuo and the residue was washed with hexane and Et2O. The solid crude product was recrystallized from THF–Et2O–hexane to afford crystals or crystalline solid. Compound 1: Orange-yellow crystals. Yield: 80 mg (37%). 1H NMR (CDCl3): d 3.45 (m, 8H, CH3CH2CH2CH2), 1.84 (m, 8H, CH3CH2CH2CH2), 1.46 (m, 8H, CH3CH2CH2CH2), 1.02 (t, 12H, CH3CH2CH2CH2). 19F {1H} NMR (CDCl3): d 157.4, 168.1, 170.2. Anal. Calc. for C40H36F20N2O4Ru: C, 44.1; H, 3.33; N, 2.57. Found: C, 44.6; H, 3.51; N, 2.71%. Compound 2: Orange crystalline solid. Yield: 79 mg (39%). 1H NMR (CDCl3): d 6.79 (m, 4H, OC6F4H), 3.32 (m, 8H, CH3CH2CH2CH2), 1.84 (m, 8H, CH3CH2CH2CH2), 1.44 (m, 8H, CH3CH2CH2CH2), 0.99 (t, 12H, CH3CH2CH2CH2). 19F {1H} NMR (CDCl3): d 145.8, 157.8 ppm. Anal. Calc. for C40H40F16N2O4Ru: C, 47.2; H, 3.96; N, 2.75. Found: C, 47.0; H, 4.66; N, 2.71%. Compound 3: Orange-red crystalline solid. Yield: 166 mg (36%). 1 H NMR (CDCl3): d 3.60 (m, 8H, CH3CH2CH2CH2), 1.43 (m, 8H, CH3CH2CH2CH2), 1.10 (m, 8H, CH3CH2CH2CH2), 1.05 (t, 12H, CH3CH2CH2CH2). Anal. Calcd. for C40H36Br20N2O4Ru: C, 20.8; H, 1.57; N, 1.21. Found: C, 20.2; H, 1.90; N, 1.20%. 2.2.2. [Bun4N][Os(N)(OR)3Cl] (R = C6F5 (4), C6F4H (5), C6Br5 (6)) A mixture of [Bun4N][Os(N)Cl4] (100 mg, 0.17 mmol) and Na(OR) (0.51 mmol) in THF (25 mL) was stirred at room temperature overnight. The solvent of filtrate was removed in vacuo and the residue was washed with hexane and Et2O. The crude product was recrystallized from THF–Et2O–hexane to afford crystals or crystalline solid. Compound 4: Yellow solid. Yield: 75 mg (43%). 1H NMR (CDCl3): d 3.15 (m, 8H, CH3CH2CH2CH2), 1.60 (m, 8H, CH3CH2CH2CH2), 1.41 (m, 8H, CH3CH2CH2CH2), 0.99 (t, 12H, CH3CH2CH2CH2). 19F {1H} NMR (CDCl3): d 157.8, 158.1, 158.6, 164.6, 167.7, 168.2. Anal. Calc. for C34H36ClF15N2O3Os: C, 35.60; H, 3.52; N, 2.72. Found: C, 36.20; H, 3.45; N, 2.83%. Compound 5: Yellow solid. Yield: 75 mg (45%). 1H NMR (CDCl3): d 6.61 (m, 3H, OC6F4H), 3.45 (m, 8H, CH3CH2CH2CH2), 1.88 (m, 8H, CH3CH2CH2CH2), 2.98 (m, 8H, CH3CH2CH2CH2), 0.98 (t, 12H, CH3CH2CH2CH2). 19F {1H} NMR (CDCl3): d 142.4, 144.4, 156.8, 157.9, 162.9. Anal. Calc. for C34H39ClF12N2O3Os: C, 41.8; H, 4.02; N, 2.87. Found: C, 41.7; H, 4.10; N, 3.00%. Compound 6: Red crystals. Yield: 76 mg (23%). 1H NMR (CDCl3): d 3.32 (m, 8H, CH3CH2CH2CH2), 1.84 (m, 8H, CH3CH2CH2CH2), 1.44 (m, 8H, CH3CH2CH2CH2), 0.99 (t, 12H, CH3CH2CH2CH2). Anal. Calc. for C34H36Br15ClN2O3Os: C, 21.0; H, 1.87; N, 1.44. Found: C, 21.8; H, 2.00; N, 1.40%. 2.2.3. [Bun4N][M(N)(SC6F4H)4] (M = Ru (7), Os (8)) A mixture of [Bun4N][M(N)Cl4] (100 mg; M = Ru (0.2 mmol), Os (0.17 mmol)) and Na(SC6F4H) in THF (25 mL) was stirred at room temperature overnight. The solvent of filtrate was removed in vacuo and the residue was washed with hexane and Et2O. The solid crude product was recrystallized from CH2Cl2–hexane or THF– Et2O–hexane to afford crystalline solid. Compound 7: Orange-yellow solid. Yield: 82 mg (38%). 1H NMR (CDCl3): d 7.24 (m, 4H, SC6F4H), 3.67 (m, 8H, CH3CH2CH2CH2), 1.82
(m, 8H, CH3CH2CH2CH2), 1.43 (m, 8H, CH3CH2CH2CH2), 0.98 (t, 12H, CH3CH2CH2CH2). 19F {1H} NMR (CDCl3): d 131.3, 142.6. Anal. Calc. for C40H40F16N2S4Ru: C, 44.4; H, 3.73; N, 2.59. Found: C, 43.0; H, 4.60; N, 2.80%. Compound 8: Yellow solid. Yield: 70 mg (35%). 1H NMR (CDCl3): d 7.34 (m, 4H, SC6F4H), 3.16 (m, 8H, CH3CH2CH2CH2), 1.85 (m, 8H, CH3CH2CH2CH2), 1.44 (m, 8H, CH3CH2CH2CH2), 0.99 (t, 12H, CH3CH2CH2CH2). 19F {1H} NMR (CDCl3): d 132.1, 142.6. Anal. Calc. for C40H40F16N2OsS4?2CH2Cl2: C, 37.6; H, 3.31; N, 2.09. Found: C, 37.7; H, 3.21; N, 1.97%. 2.2.4. [Bun4N][M(N)(Sxyl)4] (xyl = 2,6-dimethylphenyl; M = Ru (9), Os(10)) A mixture of [Bun4N][M(N)Cl4] (M = Ru; 100 mg, 0.2 mmol, M = Os; 100 mg, 0.17 mmol) and Na(Sxyl) in THF (25 mL) was stirred at room temperature overnight. The solvent of filtrate was removed in vacuo and the residue was washed with hexane and Et2O. The solid crude product was recrystallized from CH2Cl2–hexane or THF–Et2O–hexane to afford crystals or crystalline solid. Compound 9: Orange crystals. Yield: 85 mg (47%). 1H NMR (CDCl3): d 6.85 (m, 12H, phenyl), 3.46 (m, 8H, CH3CH2CH2CH2), 2.71 (s, 24H, Me), 1.85 (m, 8H, CH3CH2CH2CH2), 1.60 (m, 8H, CH3CH2CH2CH2), 0.98 (t, 12H, CH3CH2CH2CH2) ppm. Anal. Calc. for C48H72N2RuS4?CH2Cl2: C, 59.4; H, 7.52; N, 2.83. Found: C, 59.5; H, 7.70; N, 2.70%. Compound 10: Yellow solid. Yield: 83 mg (49%). 1H NMR (CDCl3): d 6.83 (m, 12H, phenyl), 3.62 (m, 8H, CH3CH2CH2CH2), 2.82 (s, 24H, Me), 1.81 (m, 8H, CH3CH2CH2CH2), 1.43 (m, 8H, CH3CH2CH2CH2), 0.99 (t, 12H, CH3CH2CH2CH2). Anal. Calc. for C48H72N2OsS4?CH2Cl2: C, 54.5; H, 6.90; N, 2.59. Found: C, 54.1; H, 7.02; N, 2.50%. 2.3. X-ray crystallography Complexes 1, 6, and 9THF have been characterized by X-ray diffraction studies. Intensity data were collected on a Bruker SMART
Table 1 Crystallographic data and experimental details for [Bun4N][Ru(N)(OC6F5)4] (1), [Bun4N][Os(N)(OC6Br5)3Cl] (6), and [Bun4N][Ru(N)(Sxyl)4] THF (9THF).
Formula Formula weight a (Å) b (Å) c (Å) a (o) b (o) c (o) V (Å3) Z Crystal system Space group Dcalc (g cm3) T (K) l (mm1) F(0 0 0) Number of reflections Number of independent reflections Rint R1, wR2 (I > 2r(I)) R1, wR2 (all data) Goodness-of-fit (GOF)a a
1
6
9THF
C40H36F20N2O4Ru 1089.78 10.0983(7) 23.3803(17) 18.5893(14) 90 90.9850(10) 90 4388.3(6) 4 monoclinic C2/c 1.649 173(2) 0.485 2184 13 987
C33H34Br15ClN2O3Os 1930.92 16.5100(11) 18.4444(13) 19.0686(13) 90 111.7590(10 90 5393.0(6) 4 monoclinic P21/n 2.378 173(2) 13.559 3552 38 629
C52H80N2ORuS4 978.49 11.7144(13) 15.1225(16) 15.2081(16) 89.812(2) 83.824(2) 74.508(2) 2580.3(5) 2 triclinic P1 1.259 100(2) 0.503 1044 12 806
3733
11 619
8723
0.0246 0.0356, 0.0876
0.0426 0.0454, 0.1025
0.0504 0.0551, 0.0898
0.042, 0.090
0.0869, 0.1127
0.1061, 0.1008
1.033
0.951
0.974
GoF = [(Rw|Fo| |Fc|)2/(Nobs Nparam)]½.
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Table 2 Selected bond lengths (Å) and angles (o) for 1. Ru(1A)–N(1) Ru(1A)–O(1)#1 Ru(1A)–O(1)
1.568(4) 1.980(2) 1.980(2)
Ru(1A)–O(2)#1 Ru(1A)–O(2)
1.980(2) 1.980(2)
N(1)–Ru(1A)–O(1)#1 N(1)–Ru(1A)–O(1) O(1)#1–Ru(1A)–O(1) N(1)–Ru(1A)–O(2)#1 O(1)#1–Ru(1A)–O(2)#1
106.69(6) 106.69(6) 146.62(12) 108.98(6) 84.82(7)
O(1)–Ru(1A)–O(2)#1 N(1)–Ru(1A)–O(2) O(1)#1–Ru(1A)–O(2) O(1)–Ru(1A)–O(2) O(2)#1–Ru(1A)–O(2)
84.46(7) 108.98(6) 84.46(7) 84.82(7) 142.05(12)
Symmetry transformations used to generate equivalent atoms: #1 x + 1, y, z + 3/ 2.
Table 3 Selected bond lengths (Å) and angles (o) for 6. Os(1)–N(1) Os(1)–O(1) Os(1)–O(3)
1.611(6) 1.974(4) 1.976(4)
Os(1)–O(2) Os(1)–Cl(1)
1.987(4) 2.2901(16)
N(1)–Os(1)–O(1) N(1)–Os(1)–O(3) O(1)–Os(1)–O(3) N(1)–Os(1)–O(2) O(1)–Os(1)–O(2)
106.6(2) 106.2(2) 146.50(18) 106.1(2) 84.74(17)
O(3)–Os(1)–O(2) N(1)–Os(1)–Cl(1) O(1)–Os(1)–Cl(1) O(3)–Os(1)–Cl(1) O(2)–Os(1)–Cl(1)
79.69(17) 102.3(2) 90.41(13) 89.34(12) 151.37(13)
APEX 1000 CCD diffractometer using graphite-monochromated Mo Ka radiation (k = 0.71073 Å). The collected frames were processed with the software SAINT [27]. Structures were solved by the direct methods and refined by full-matrix least-squares on F2 using the SHELXTL software package [28]. Atomic positions of non-hydrogen atoms were refined with anisotropic parameters and with suitable restraints except the co-crystallized THF molecule in 9. Hydrogen atoms were generated geometrically and allowed to ride on their respective parent carbon atoms before the final cycle of leastsquares refinement. Crystallographic data and experimental details for compounds 1, 6, and 9THF are listed in Table 1. Selected bond distances and angles of these compounds are listed in Table 2–4 and their structures are shown in Figs. 2–4, respectively. In complex 1, the disordered ruthenium atom was split into two sites, Ru1A and Ru1B, with occupancy of 0.98 and 0.02, respectively. In complex 6, the bromine atoms Br13, Br14, Br15 in the C11–C12–C13–C14–C15–C16 phenyl rings and Br33 and Br34 in the C31–C32–C33–C34–C35–C36 phenyl ring were found to be disorder. Each of these bromine atoms were split into two sites with occupancy of 0.5 each. In complex 9, the disordered Ru and N atoms were split into two sites (Ru1 and Ru1A and N1 and N1A) with occupancies of 0.9 and 0.1, respectively. Also, the co-crystallized THF molecule was 50:50 disordered.
3. Results and discussion Table 4 Selected bond lengths (Å) and angles (o) for 9THF.
3.1. Halogenated phenoxide compounds
Ru(1)–N(1) Ru(1)–S(2) Ru(1)–S(4)
1.615(4) 2.3547(11) 2.3571(12)
Ru(1)–S(1) Ru(1)–S(3)
2.3641(11) 2.3672(12)
N(1)–Ru(1)–S(2) N(1)–Ru(1)–S(4) S(2)–Ru(1)–S(4) N(1)–Ru(1)–S(1) S(2)–Ru(1)–S(1)
108.52(13) 107.49(13) 143.97(5) 106.24(13) 84.23(4)
S(4)–Ru(1)–S(1) N(1)–Ru(1)–S(3) S(2)–Ru(1)–S(3) S(4)–Ru(1)–S(3) S(1)–Ru(1)–S(3)
84.89(4) 106.37(13) 85.72(4) 85.23(4) 147.38(5)
The syntheses of Ru(VI) and Os(VI) nitrido complexes with halogenated phenoxide ligands are summarized in Scheme 1. Treatment of [Bun4N][Ru(N)Cl4] with Na(OR) afforded the tetraphenoxide complexes [Bun4N][Ru(N)(OR)4] (R = C6F5 (1), C6F4H (2), C6Br5 (3)), which could be isolated as air-stable orange crystals in 36–39% yield. Although NMR spectroscopy indicated that the reaction between [Bun4N][Ru(N)Cl4] with Na(OR) is clean,
Fig. 1. 1H NMR spectrum (300 MHz, 298 K) of 2 in CD3CN solution.
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complexes 1–3 are not isolated in high yields mainly because of difficulty in crystallization. To our knowledge, these are the first isolated Ru(VI) nitrido complexes with halogenated phenoxide ligands. Compounds 1–3 are soluble in CH2Cl2 and polar solvents such as acetone, but insoluble in Et2O and hexane. It should be noted that the halogen substituents of the phenoxide ligands is essential for the isolation of Ru(VI) nitrido phenoxide complexes. Reaction of [Bun4N][Ru(N)Cl4] with non-halogenated phenoxides, e.g. sodium phenoxide and sodium 2,6-dimethylphenoxide, resulted in intractable materials that did not crystallize. In the 1H NMR spectrum of 2, the phenyl protons (C6F4H) appeared as a multiplet at d 6.79 ppm in CDCl3 and d 7.25 ppm in CD3CN (Fig. 1). The 19 F NMR spectrum of 1 displayed three resonances at d 157.4, 168.1 and 170.2 ppm, whereas two doublets at d 145.8 and 157.8 ppm were observed for 2. Unlike the Ru(salen) nitrido complexes [16], complexes 1–3 are stable in donor solvents such as acetonitrile. No bimolecular N N coupling reaction was found. They reacted readily with PPh3 to give Ph3P = N = PPh3+ characterized by 31P NMR spectroscopy (d 22 ppm) along with paramagnetic species, possibly Ru(III) complexes, which have yet been characterized. A similar reaction involving an Os(VI) nitrido complex, [Os(tpy)Cl2(N)]+ (tpy = 2,20 :60 ,200 -terpyridine), has been reported [29]. Treatment of [Bun4N][Os(N)Cl4] with four equivalents of Na(OR) led to isolation of the triphenoxide complexes [Bun4N][Os(N)(OR)3Cl] (R = C6F5 (4), C6F4H (5), C6Br5 (6)) along with uncharacterized side-products, possibly the tetraphenoxide complex. The yields of the triphenoxide complexes were optimized when 3 equivalents of the phenoxide were employed. Complexes 4–6 are air stable in both the solid state and solutions. In the 1H NMR spectrum of 5 in CDCl3, the phenyl protons of the tetrafluorophenoxide ligands of appeared as an unresolved multiplet at d 6.61 ppm.
Fig. 2. Thermal ellipsoid plot (50% probability level) of the complex anion in 1.
M = Ru
[Bun4N]
Ru
[Bun4N][M(N)Cl4]
OR OR
RO
R = C6F5 (1) = C6F4H (2) = C6Br5 (3)
Na(OR)
3.2. Thiophenoxide compounds Treatment of [Bun4N][M(N)Cl4] with NaSC6F4H led to isolation of air-stable red solids characterized as [Bun4N][M(N)(SC6F4H)4] (M = Ru (7), Os (8)) (Scheme 2). Unlike the phenoxide analogues, Ru(VI) and Os(VI) nitrido complexes with non-halogenated thiophenoxide ligands could also be synthesized. Thus, treatment of [Bun4N][M(N)Cl4] with NaSxyl (xyl = 2,6-dimethylphenyl) afforded [Bun4N][M(N)(Sxyl)4] (M = Ru (9), Os (10)). The resonances of the phenyl proton in 7 and 8 were observed as multiplets at d 7.24 and 7.34 ppm, respectively, which are more downfield than those of the phenoxide analogues 2 and 5. The 1H NMR spectra of 9 and 10 displayed a singlet at d 2.71 and 2.82 ppm, respectively, which are attributable to the magnetically equivalent methyl protons.
N RO
M = Os
[Bun4N]
N RO RO
Os
Cl OR
R = C6F5 (4) = C6F4H (5) = C6Br5 (6) Scheme 1.
3.3. Crystal structures Compounds 1, 6, and 9THF have been characterized by X-ray diffraction studies. Fig. 2 shows the structure of the complex anion in 1. The geometry around Ru atom is pseudo square pyramidal with the nitrido group at the apical position. The Ru is displaced above the mean O4 plane by ca. 0.606 Å that is comparable to that in [Ru(N)(cat)2] (cat2 = catecholate) (0.62 Å) [22]. The Ru–N distance of 1.568(4) Å is typical for Ru(VI) nitrido compounds and compares well with that in [AsPh4][Ru(N)Br4] (1.578 Å) [30] but is slightly shorter than that for [Bun4N][Ru(N)(cat)2] (1.603(4) Å) [22]. The Ru–O distances (1.980(2) Å) are longer than those in [Bun4N][Ru(N)(cat)2] (1.954(3)–1.962(2) Å) [22]. The rather large Ru–O–C angles (120.8(2)–125.6(2)o) are indicative of Ru–O p interactions. The structure of complex 6 is similar to that of 1 with the nitrido group at the apical position (Fig. 3). The Os is displaced above the O3Cl plane by ca. 0.540 Å. The Os–N distance of 1.611(6) Å is slightly shorter than that in [Bun4N][Os(N)(cat)2] (1.641(8) Å), whereas the Os–O distances (av. 1.976 Å) are comparable to those
Fig. 3. Thermal ellipsoid plot (50% probability level) of the complex anion in 6.
in [Bun4N][Os(N)(cat)2] (av. 1.971 Å) [22]. The Os–O–C angles in the range of 124.6(3)–127.9(3)o are slightly larger than those in 1. The
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Council (Project No.: 602104) is gratefully acknowledged. Q.-F. Zhang thanks the Program for New Century Excellent Talents in University of China (NCET-06-0556) for support. Appendix A. Supplementary material CCDC 724305, 724306, and 724307 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. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.ica.2009.09.029. References
Fig. 4. Thermal ellipsoid plot (50% probability level) of the complex anion in 9. All hydrogen atoms are omitted for clarity.
[Bun4N][M(N)Cl4]
Na(SR)
[Bun4N]
N RS RS
M
SR SR
R = C6F4H, M = Ru (7) R = C6F4H, M = Os (8) R = 2,6-Me2C6H3, M = Ru (9) R = 2,6-Me2C6H3, M = Os (10) Scheme 2.
Os-Cl distance of 2.290(2) Å is comparable to that in [Ph4P][OsNCl4] (2.3099 (4) Å) [31]. In complex 9THF, the geometry around Ru is pseudo square planar with the nitrido group at the apical position (Fig. 4). The Ru is displaced above the mean S4 plane by ca. 0.696 Å that is comparable to that in [Ru(N)(bdt)2] (bdt2 = benzene-1,2-dithiolate) (0.69 Å). The Ru–N distance of 1.615(4) Å is slightly longer than that in 1, but compares well with that of [Ru(N)(bdt)2] (1.613(5) Å). The Ru–S distances (2.355(1)–2.367(1) Å) in 9 are similar to that in [Ru(N)(bdt)2] (2.317(2)–2.330(2) Å) [32]. The Ru–S–C angles (111.7(1)–112.1(1)o) are smaller than the Ru–O–C angles in 1. 4. Conclusions We have synthesized and structurally characterized Ru(VI) and Os(VI) nitrido complexes with halogenated phenoxide ligands. It was found that the halogen substituents of the phenoxide ligands are important for the synthesis of Ru(VI) nitrido phenoxide complexes. We have also synthesized Ru(VI) and Os(VI) nitrido complexes with tetrafluorothiophenoxide and 2,6-dimethylthiophenoxide ligands. Acknowledgements We thank Dr. Herman H.Y. Sung for solving the crystal structures. The financial support from the Hong Kong Research Grants
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