ARTICLE

DOI: 10.1002/zaac.201100163

Syntheses and Molecular Structure of Dinuclear Transition MetalComplexes Bridged by Dipyridylamine Derivative Ligands

Gajendra Gupta,[a] Sunhong Park,[b] Shim Sung Lee,[b] and Jinkwon Kim*[a]

Keywords: Dipyridylamine ligands; Ruthenium; Rhodium; Iridium; Structure eludcidation

Abstract. Stable dinuclear transition metal complexes,[(η6-C6H6)2Ru2(L1)Cl2]2+ (1), [(η6-p-iPrC6H4Me)2Ru2(L1)Cl2]2+ (2),[(η6-C6Me6)2Ru2(L1)Cl2]2+ (3), [(η6-C6H6)2Ru2(L2)Cl2]2+ (4),[(η6-p-iPrC6H4Me)2Ru2(L2)Cl2]2+ (5), [(η6-C6Me6)2Ru2(L2)Cl2]2+ (6),[(η5-C5Me5)2Rh2(L1)Cl2]2+ (7), [(η5-C5Me5)2Ir2(L1)Cl2]2+ (8),[(η5-C5Me5)2Rh2(L2)Cl2]2+ (9), and [(η5-C5Me5)2Rh2(L2)Cl2]2+ (10),with the bis-bidentate ligands 1,3-bis(di-2-pyridylaminomethyl)ben-

1 Introduction

The synthesis of metal complexes with multiple coordinationdomains is an area of significant current interest in organome-tallic chemistry. Such complexes were prepared as part of stud-ies in diverse areas such as intermetallic communication,[1]

bioinorganic enzyme active site modeling,[2] supramolecularapproaches to chiral materials,[3] and functional devices.[4] Theorganometallic chemistry of half-sandwich complexes werebroadly developed in the past few decades, due to their widerange of potential applications as catalyst precursors for hydro-gen transfer,[5,6] ring opening metathesis polymerization,[7,8]

and olefin oxidation.[9] The coordination chemistry of 2,2-di-pyridylamine (dpa) and its derivatives was in the focus ofa considerable number of investigations. For example, mono-,di- and tri-dpa derivatives were reported, in which the second-ary nitrogen atom of each dpa is directly bound to an aryl corewith such species being employed in studies that range frommetal coordination to supramolecular chemistry[10,11] and thesynthesis of new luminescent materials.[12–14] Supramolecularmaterials containing silver(I) ions have received increasingattention, partly due to the coordination flexibility of this d10ion and its strong tendency to form metal complexes throughnitrogen donor ligands. It is well established that upon coordi-nation with the metal atoms pyridyl rings of dpa adopt eithernearly co-planar or inclined pyridyl ring planes. On the other

* Prof. Dr. J. KimE-Mail: jkim@kongju.ac.kr

[a] Department Of ChemistryKongju National University182 ShinkwanKongju-Chungnam 314-701, Republic of Korea

[b] Department of Chemistry and Research Institute of NaturalScienceGyeongsang National UniversityJinju 660-701, Republic of Korea

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zene (L1) and 1,4-bis(di-2-pyridylaminomethyl)benzene (L2), whichcontain two chelating dipyridylamine units connected by an aromaticspacer, were synthesized. The cationic dinuclear complexes were iso-lated as their hexafluorophosphate salts and characterized by using acombination of NMR, IR, and UV/Vis spectroscopic methods and massspectrometry. The solid-state structure of complex 8 as a representativewas determined by X-ray structure analysis.

hand ruthenium compounds with arene ligands were alsoextensively investigated for their persuasive antibacterial andanticancer activity.[15,16] The arene group confers great stabilityto ruthenium in the +2 oxidation state and the characteristic“piano stool” structure offers the possibility to vary the addi-tional donors via substitution of halide(s) with a variety of σdonors ranging from tertiary phosphines,[17] to β-diketones,[18]

and to aliphatic as well as aromatic amines.[19–21]

In recent years, we carried out reactions of arene ruthenium,rhodium, and iridium dimers with a variety of nitrogendonors,[22–30] such as pyridyl-pyridazine and pyrazolyl-pyrida-zine ligands. Arene metal complexes of these types of nitro-gen-donor ligands have the capacity to function as catalystsfor the oxidation of water to dioxygen.[31,32] Herein wedescribe the syntheses of ten stable dinuclear η5- and η6- cyclicΠ-perimeter hydrocarbons platinum group metal compoundsbearing dipyridylamine derivative ligands 1,3-bis(di-2-pyridyl-aminomethyl)benzene (L1) and 1,4-bis(di-2-pyridylamino-methyl)benzene (L2). All these compounds are completelycharacterized by IR and NMR spectroscopy as well as massspectrometry. Some of the representative compounds are alsocharacterized by single-crystal X-ray diffraction and UV/Visspectroscopy. Ligands used in this study are shown below:

Dinuclear Transition Metal Complexes with Dipyridylamine

2 Results and Discussion

2.1 Dinuclear Arene Ruthenium Complexes 1–6

The dinuclear arene ruthenium complexes [(η6-arene)Ru(μ-Cl)Cl]2 react with the tetradentate bis(dipyridylamino-methyl)benzene ligands in methanol to afford the cationic di-nuclear complexes [(η6-C6H6)2Ru2(L1)Cl2]2+ (1),[(η6-p-iPrC6H4Me)2Ru2(L1)Cl2]2+ (2),[(η6-C6Me6)2Ru2(L1)Cl2]2+ (3), [(η6-C6H6)2Ru2(L2)Cl2]2+ (4),[(η6-p-iPrC6H4Me)2Ru2(L2)Cl2]2+ (5), and[(η6-C6Me6)2Ru2(L2)Cl2]2+ (6), isolated as their hexafluoro-phosphate salts (Scheme 1 and Scheme 2). Compounds 1 and4 are brown, whereas compounds 2, 3, 5, and 6 are yellow.These salts are non-hygroscopic and stable in air as well asin solution. They are sparingly soluble in polar solvents likedichloromethane, chloroform, acetone, and acetonitrile but in-soluble in non-polar solvents. All compounds are characterizedby 1H NMR and IR spectroscopy, as well as mass spectrometryand representative complexes are also characterized by UV/Visspectroscopy. The analytical data of these compounds are inagreement with the formulations. In the mass spectra, theyshow the expected molecular ion peaks m/z at 915.2, 1027.4,1083.6, 915.5, 1028, and 1083.1 corresponding to compounds1 to 6. All these halogenated complexes also display prominentpeaks corresponding to the loss of both chloride ions from themolecular ion peak [M – (PF6)2]+, but the loss of the arenegroup is not observed indicating the stronger bond of metal tothe arene group. The IR spectra of these complexes exhibit asharp band due to chelated tetradentate ligands between 1625and 1616, and 1481 and 1437 cm–1 corresponding to the differ-ent νC=C and νC=N of these complexes (see Experimental Sec-tion). In addition, the infrared spectra contain a strong band inthe range 842–844 cm–1 due to the νP–F vibration of the coun-terions for complexes 1 to 6. The 1H NMR spectra of thesecomplexes were recorded in CDCl3 and spectroscopic data aresummarized in the Experimental Section. The protons of theligand in these complexes 1–6 show downfield shifts with re-spect to the protons of the free ligand. The NMR spectra of theuncoordinated ligands display signals between 7.79–5.11 ppm,whereas in the case of the metal complexes these signals areshifted to the downfield region between 8.54–5.32 ppm. In ad-dition to the aromatic protons from the ligand skeleton, com-plexes 1 and 4 show singlet signals at 6.07 and 5.11 ppm,which correspond to the protons of the benzene groups of thesecomplexes. The 1H NMR spectra of complexes 2 and 5 exhibittwo doublet signals in the range of 5.27–5.13 ppm, which cor-respond to the aromatic p-cymene ring of the CH protons.Complexes 2 and 5 also exhibit singlet signals at 2.31 and2.27 ppm, doublet signals at 0.95 and 0.93 ppm, and septetsignals at 2.39 and 2.66 ppm for the protons of the methyl andisopropyl groups of the p-cymene ligands. However, com-plexes 3 and 6 exhibit sharp singlet signals at 1.92 and1.95 ppm for the hexamethlybenzene ligands, which areshifted towards high field compared to 2.04 ppm of the startingcomplex [(η6-C6Me6)Ru(μ-Cl)Cl]2.

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Scheme 1.

Scheme 2.

2.2 Pentamethylcyclopentadienyl Dinuclear Rhodium andIridium Complexes 7–10

The dinuclear complexes [(η5-C5Me5)M(μ-Cl)Cl]2 (M = Rhor Ir) undergo a bridge cleavage reaction with the tetradentatenitrogen base ligands in methanol at room temperature, whichlead to the formation of chloride-displaced complexes 7–10,respectively (Scheme 1 and Scheme 2).These complexes were also isolated as their hexafluorophos-phate salts. The orange-yellow complexes are air stable andsoluble in polar solvents. The infrared spectra of all these com-plexes exhibit broad bands of chelating tetradentate ligands inthe regions 1651–1635 cm–1 for C=C stretching modes and1445–1437 cm–1 for C=N stretching modes. The νP–F stretch-ing vibration of the counterion of these complexes was alsoobserved at 843 and 844 cm–1. The m/z values of all thesecomplexes and their stable ion peaks obtained from the ESImass spectra are listed in the Experimental Section and are ingood agreement with the theoretically expected values. Thesehalogenated complexes display prominent peaks correspondingto the loss of chloride ion from the molecular ion peak, but theloss of Cp* group is not observed, which indicates that thestronger bond between the metal ion and this group remainsintact. In the 1H NMR spectra of complexes 7–10 the ligandsignals are spread to the downfield region as compared to thatof the free ligand. The proton signals of the bridging ligandsare shifted downfield in the range 8.59–5.16 ppm. The down-field shift of the proton signals might result from a change inthe electron density on the metal atom due to the chelation ofthe ligand through two nitrogen atoms. The 1H NMR spectra

G. Gupta, S. Park, S. S. Lee, J. KimARTICLE

of complexes 7–10 show singlet signals at 2.17, 2.54, 1.57,and 1.63 ppm, respectively, which correspond to the protons ofthe pentamethylcyclopentadienyl groups of these complexes.

2.3 Molecular Structure of 8·(PF6)2·3CH3CN·(CH3)2CO

The molecular structure of compound 8 was established bysingle-crystal X-ray analysis of its hexafluorophosphate salt.The complex crystallizes in the orthorhombic space group withthree acetonitrile molecules and an acetone molecule locatedin the cavities of the crystal. The molecular structure of com-pound 8 is displayed in Figure 1. Selected bond lengths andbond angles are summarized in Table 1 and crystallographicdetails are summarized in Table 2. The overall arrangement ofthis structure corresponds to the characteristic three legged pi-ano-stool. This complex contains two metal atoms bonded toη5-C5Me5 ligands, which are bridged by a dipyridylamine li-gand. The aromatic ring occupies three coordination sites inthis complex to complete the octahedral arrangement aroundthe metal atoms. The distance between the iridium atom andthe center of the η5-C5Me5 ring is 1.784 Å, which is similar tothose observed in the related complexes. The Ir1–N1 and Ir1–Cl1 bond lengths are 2.090(4) and 2.391(1) Å respectively,which are also closely similar to reported polypyridyl metalcomplexes.[25,27] The N1–Ir1–N2 bond angle is around

Figure 1. ORTEP diagram of complex 8 at 50 % probability level.Hydrogen atoms, acetonitrile, acetone, and hexafluorophosphate anionare omitted for clarity (symmetry code: x, –y + 1/2, z).

Table 1. Selected bond lengths /Åand angles /° for complex 8.

Interatomic distances

Ir1–N1 2.090(4)Ir1–N2 2.084(4)Ir1–Cl1 2.391(1)Ir1–centroida) 1.784Ir1···Ir1 9.284

Angles

N1–Ir1–N2 82.1(2)N1–Ir1–Cl1 87.8(1)N2–Ir1–Cl1 87.6(1)Symmetry code x, –y + 1/2, z.

a) Calculated centroid-to-metal distances (η5-C5Me5 coordinated aro-matic ring).

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Table 2. Crystallographic and structure refinement parameters forcomplex 8·(PF6)2·3CH3CN·(CH3)2CO.

Chemical formula C57H69Cl2F12Ir2N9OP2Formula weight 1641.46Crystal system OrthorhombicSpace group PnmaCrystal size 0.27 × 0.13 × 0.12a /Å 15.8285(4)b /Å 31.7318(9)c /Å 12.3448(3)V /Å3 6200.4(3)Z 4T /K 296(2)Dc /g·cm–3 1.758μ /mm–1 4.509Scan range /° 1.77 < θ < 27.00Unique reflections 59688Reflections used [I > 2σ(I)] 6899Rint 0.0756Final R indices [I > 2σ(I)]a) 0.0344, wR2 0.0753R indices (all data) 0.0534, wR2 0.0879Goodness-of-fit 1.082Max, min Δρ /e·Å–3 1.298, –1.285

a) Structures were refined on Fo2: wR2 = [Σ [ w (Fo2 – Fc2)2] /Σw(Fo2)2]1/2, where w – 1 = [Σ(Fo2) + (aP)2 + bP] and P = [max (Fo2,0) + 2Fc2]/3.

82.1(2)°. There are no significant differences in the C–C bondlengths in the pentamethylcyclopentadienyl ring.

2.4 UV/Vis Spectroscopy

UV/Vis spectra of the complexes 2, 3, 4, 8, 9, and 10 wereacquired in acetonitrile and spectroscopic data are summarizedin Table 3. Electronic spectra of representative complexes aredepicted in Figure 2. The low spin d6 configuration of thesedinuclear complexes provides filled orbitals of proper symme-try at RuII atoms, which can interact with the low lying π*orbital of the ligands. One should therefore expect a band at-tributable to the metal-to-ligand charge transfer (MLCT)t2g→π* transition in their electronic spectra.[33–38] The elec-tronic spectra of these complexes display a medium intensityband in the UV/Vis region. The lowest energy absorptionbands in the electronic spectra of these complexes in the visi-ble region ≈ 409–401 and ≈ 399–346 nm are tentatively as-signed on the basis of their intensity and position to t2g→π*MLCT transitions. The bands on the high energy side at ≈306–232 nm for the complexes 2, 3, 4, 8, 9, and 10, are as-signed to ligand-centered π→π*/n→π* transitions.[39,40] Ingeneral, these complexes follow the normal trends observed inthe electronic spectra of the nitrogen-bonded metal complexes,which display a ligand-based π→π* transition for dipyridylam-ine ligands in the UV region and metal-to-ligand charge trans-fer transitions in the visible region.

3 ConclusionsA series of ten stable dinuclear η5- and η6-cyclic hydrocar-

bon transition metal complexes with nitrogen based deriva-

Dinuclear Transition Metal Complexes with Dipyridylamine

Table 3. UV/Vis absorption data in acetonitrile at 298 K.

λmax /nm (ε /10–4 M–1·cm–1)

2 232 298 (1.03) 400 (0.06)(0.68)

3 235263 (1.00) 306 (0.94) 394 (0.06)(0.99)

4 232248 (0.58) 280 (0.42) 388 (0.06)(0.56)

8 248281 (0.694) 304 (0.419) 410 (0.03)(0.83)

9 250288 (0.58) 346 (0.10) 405 (0.02)(0.53)

10 253281 (0.64) 301 (0.47) 402(0.03)(0.78)

Figure 2. UV/Vis absorption spectra of dinuclear complexes 2, 3, 4,8, 9, and 10 in acetonitrile at 298 K.

tives, which contain two chelating dipyridylamine units con-nected by an aromatic spacer, were synthesized. The cationicdinuclear complexes are isolated as their hexafluorophosphatesalts and fully characterized by use of a combination of NMR,IR, and UV/Vis spectroscopic methods and by mass spectrom-etry.

4 Experimental Section4.1 Physical Measurements

Infrared spectra were recorded with a Perkin–Elmer Model 983 spec-trophotometer with the sample prepared as KBr pellets. The NMRspectra were obtained with a Bruker Advance II 400 spectrometer inCDCl3 for complexes using TMS as an internal standard. Mass spectrawere obtained with a Waters ZQ-4000 mass spectrometer by the ESImethod. All chemicals used were of reagent grade. Elemental analysesof the complexes were performed with a Perkin–Elmer 2400 CHN/Sanalyzer. All reactions were carried out in distilled and dried solvents.The ligands L1 and L2 were prepared by following a reportedprocedure.[41] The precursor complexes [(η6-arene)Ru(μ-Cl)Cl]2 (ar-ene = C6H6, p-iPrC6H4Me and C6Me6) and [(η6-C5Me5)M(μ-Cl)Cl]2(M = Rh, Ir) were prepared by following the literature methods,[42–46]

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4.2 Single-crystal X-ray Structure Analyses

A crystal of complex 8·(PF6)2·(CH3)2CO·(CH3CN)2 was mounted on aStoe Image Plate Diffraction system equipped with a f circle goniome-ter, using Mo-Kα graphite monochromated radiation (λ = 0.71073 Å)in the range 0–200°. The structure was solved by direct methods usingthe program SHELXS-97.[47] Refinement and all further calculationswere carried out using SHELXL-97.[47] The hydrogen atoms were in-cluded in calculated positions and treated as riding atoms using theSHELXL default parameters. The non-hydrogen atoms were refinedanisotropically, using weighted full-matrix least-square on F2. Crystal-lographic details are summarized in Table 2 and selected bond lengthsand angles are presented in Table 1. Figure 1 was drawn with ORTEP-32.[48]

4.3 Preparation of [(η6-C6H6)2Ru2(L1)Cl2]2+ (1),[(η6-p-iPrC6H4Me)2Ru2(L1)Cl2]2+ (2),[(η6-C6Me6)2Ru2(L1)Cl2]2+ (3), [(η6-C6H6)2Ru2(L2)Cl2]2+ (4),[(η6-p-iPrC6H4Me)2Ru2(L2)Cl2]2+ (5),[(η6-C6Me6)2Ru2(L2)Cl2]2+(6)

A mixture of [(η6-arene)Ru(μ-Cl)Cl]2 (0.09 mmol), L1/L2 (40 mg,0.09 mmol) and an excess of NH4PF6 was stirred in dry methanol(20 mL) for 4 h at room temperature. The yellow compound was fil-tered, washed with ethanol, diethyl ether, and dried in a vacuum.

Compound 1·(PF6)2: Yield: 145 mg, 62 %. Elemental anal. forC40H36Cl2F12N6P2Ru2: calcd. C 41.30; H 3.12; N 7.20 %; found: C41.60; H 3.59; N 6.97 %. IR (KBr): ν̃ = 1625 (νC=C); 1439 (νC=N); 843(νP–F)cm–1. 1H NMR (400 MHz, CDCl3): δ = 8.33 (d, J = 6 Hz, 4 H),7.68 (t, J = 6.8 Hz, 4 H), 7.25 (t, J = 7.2 Hz, 5 H), 7.05 (d, J = 6 Hz,5 H), 6.85 (d, J = 6.8 Hz, 2 H), 6.07 (s, 12 H, C6H6), 5.32 (s, 4 H,CH2). ESI-MS (m/z): 915.2 [M – (PF6)2]+, 844.2 [M – (PF6)2 – Cl2]+,842.1 [M – (PF6)2 – Cl2 – H]+, 841.1 [M – (PF6)2 – Cl2 – 3H]+.

Compound 2·(PF6)2: Yield: 138 mg, 66 %. Elemental anal. forC48H52Cl2F12N6P2Ru2: calcd. C 45.20; H 4.12; N 6.58 %; found: C45.44; H 4.61; N 6.79 %. IR (KBr): ν̃ = 1624 (νC=C); 1481 (νC=N); 843(νP–F) cm–1. 1H NMR (400 MHz, CDCl3): δ = 8.41 (d, J = 7.6 Hz, 4H), 7.72 (dt, J = 7.2 Hz, 4 H), 7.18 (t, J = 6.8 Hz, 5 H), 7.01 (d, J =6 Hz, 5 H), 6.73 (d, J = 7.2 Hz, 2 H), 5.42 (s, 4 H, CH2), 5.27 (d, J =6 Hz, 4 H, Arp–cy), 5.18 (d, J = 6 Hz, 4 H, Arp–cy), 2.39 (sept. 2 H),2.31 (s, 6 H), 0.95 (d, J = 6.8 Hz, 12 H). ESI-MS (m/z): 1027.4 [M –(PF6)2]+, 956.3 [M – (PF6)2 – Cl2]+, 953.2 [M – (PF6)2 – Cl2 – 3H]+.

Compound 3·(PF6)2: Yield: 147 mg, 74 %. Elemental anal. forC52H60Cl2F12N6P2Ru2: calcd. C 46.86; H 4.58; N 6.31 %; found: C

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47.07; H 4.90; N 6.04 %. IR (KBr): ν̃ = 1599 (νC=C); 1437 (νC=N); 844(νP–F) cm–1. 1H NMR (400 MHz, CDCl3): δ = 8.50 (dd, J = 7.6 Hz, 4H), 7.75 (dt, J = 7.2 Hz, 4 H), 7.33 (t, J = 6.8 Hz, 5 H), 7.18 (d, J =6 Hz, 5 H), 6.91 (d, J = 6 Hz, 2 H), 5.57 (s, 4 H, CH2), 1.92 (s, 36H, C6Me6). ESI-MS (m/z): 1083.6 [M – (PF6)2]+, 1012.6 [M – (PF6)2 –Cl2]+, 1011.5 [M – (PF6)2 – Cl2 – H]+.

Compound 4·(PF6)2: Yield: 141 mg, 61 %. Elemental anal. forC40H36Cl2F12N6P2Ru2: calcd. C 41.30; H 3.12; N 7.20 %; found: C41.58; H 3.49; N 7.11 %. IR (KBr): ν̃ = 1622 (νC=C); 1475 (νC=N); 844(νP–F) cm–1. 1H NMR (400 MHz, CDCl3): δ = 8.29 (d, J = 6 Hz, 4H), 7.63 (t, J = 6.8 Hz, 4 H), 7.01 (d, J = 7.2 Hz, 4 H), 6.87 (t, J =6.8 Hz, 4 H), 6.79 (d, J = 6 Hz, 4 H), 5.51 (s, 4 H, CH2), 5.11 (s, 12H, C6H6). ESI-MS (m/z): 915.5 [M – (PF6)2]+, 844.4 [M – (PF6)2 –Cl2]+, 841.3 [M – (PF6)2 – Cl2 – 3H]+.

Compound 5·(PF6)2: Yield: 140 mg, 67 %. Elemental anal. forC48H52Cl2F12N6P2Ru2: calcd. C 45.20; H 4.12; N 6.58 %; found: C45.48; H 4.60; N 6.83 %. IR (KBr): ν̃ = 1617 (νC=C); 1451 (νC=N); 843(νP–F) cm–1. 1H NMR (400 MHz, CDCl3): δ = 8.24 (d, J = 1.6 Hz, 4H), 7.54 (t, J = 1.6 Hz, 4 H), 6.96 (d, J = 8.4 Hz, 4 H), 6.85 (t, J =6.4 Hz, 4 H), 6.82 (d, J = 1.2 Hz, 4 H), 5.57 (s, 4 H, CH2), 5.21 (d,J = 6.4 Hz, 4 H, Arp–cy), 5.13 (d, J = 6.4 Hz, 4 H, Arp–cy), 2.66 (sept.2 H), 2.27 (s, 3 H), 2.26 (s, 3 H), 0.93 (d, J = 6.8 Hz, 12 H). ESI-MS(m/z): 1028 [M – (PF6)2]+, 957.1 [M – (PF6)2 – Cl2]+, 956.2 [M –(PF6)2 – Cl2 – H]+.

Compound 6·(PF6)2: Yield: 139 mg, 70 %. Elemental anal. forC52H60Cl2F12N6P2Ru2: calcd. C 46.86; H 4.58; N 6.31 %; found: C47.09; H 4.88; N 6.10 %. IR (KBr): ν̃ = 1616 (νC=C); 1440 (νC=N); 842(νP–F) cm–1. 1H NMR (400 MHz, CDCl3): δ = 8.54 (d, J = 6 Hz, 4H), 7.83 (t, J = 6.4 Hz, 4 H, Py), 7.31 (d, J = 7.2 Hz, 4 H), 7.08 (t,J = 6.4 Hz, 4 H), 6.87 (d, J = 6 Hz, 4 H), 5.62 (s, 4 H, CH2), 1.95 (s,36 H, C6Me6). ESI-MS (m/z): 1083.1 [M – (PF6)2]+, 1012.2 [M –(PF6)2 – Cl2]+.

4.4 Preparation of [(η5-C5Me5)2Rh2(L1)Cl2]2+ (7),[(η5-C5Me5)2Ir2(L1)Cl2]2+ (8), [(η5-C5Me5)2Rh2(L2)Cl2]2+ (9),and [(η5-C5Me5)2Ir2(L2)Cl2]2+ (10)

A mixture of [(η5-C5Me5)M(μ-Cl)Cl]2 (M = Rh, Ir) (0.09 mmol), L1/L2 (40 mg, 0.09 mmol) and an excess of NH4PF6 was stirred in drymethanol (20 mL) for 4 h at room temperature. The yellow compoundwas filtered, washed with ethanol and diethyl ether, and dried in avacuum.

Compound 7·(PF6)2: Yield: 155 mg, 75 %. Elemental anal. forC48H54Cl2F12N6P2Rh2: calcd. C 45.01; H 4.27; N 6.55 %; found: C45.38; H 4.51; N 6.27 %. IR (KBr): ν̃ = 1642 (νC=C); 1445 (νC=N); 843(νP–F) cm–1. 1H NMR (400 MHz, CDCl3): δ = 8.23 (d, J = 7.6 Hz, 4H), 7.61 (dt, J = 8.4 Hz, 4 H), 7.00 (t, J = 6.8 Hz, 5 H), 6.92 (d, J =8.4 Hz, 5 H), 6.76 (d, J = 7.2 Hz, 2 H), 5.16 (s, 4 H, CH2), 2.17 (s,30 H, C5Me5). ESI-MS (m/z): 991.3 [M – (PF6)2]+, 920.2 [M – (PF6)2 –Cl2]+, 919.2 [M – (PF6)2 – Cl2 – H]+.

Compound 8·(PF6)2: Yield: 115 mg, 61 %. Elemental anal. forC48H54Cl2F12N6P2Ir2: calcd. C 39.48; H 3.75; N 5.75 %; found: C40.06; H 3.99; N 5.43 %. IR (KBr): ν̃ = 1639 (νC=C); 1439 (νC=N); 844(νP–F) cm–1. 1H NMR (400 MHz, CDCl3): δ = 8.59 (d, J = 5.2 Hz, 4H), 7.94 (dt, J = 6.8 Hz, 4 H), 7.42 (t, J = 5.6 Hz, 5 H), 7.24 (d, J =8.4 Hz, 5 H), 7.16 (d, J = 7.6 Hz, 2 H), 5.46 (s, 4 H, CH2), 2.54 (s,30 H, C5Me5). ESI-MS (m/z): 1169.7 [M – (PF6)2]+, 1098.4 [M –(PF6)2 – Cl2]+.

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Compound 9·(PF6)2: Yield: 152 mg, 73 %. Elemental anal. forC48H54Cl2F12N6P2Rh2: calcd. C 45.01; H 4.27; N 6.55 %; found: C45.35; H 4.42; N 6.29 %. IR (KBr): ν̃ = 1635 (νC=C); 1437 (νC=N); 843(νP–F) cm–1. 1H NMR (400 MHz, CDCl3): δ = 8.34 (d, J = 4 Hz, 4H), 7.97 (d, J = 7.6 Hz, 4 H), 7.80 (t, J = 6.4 Hz, 4 H), 7.16 (t, J =1.2 Hz, 4 H), 7.13 (d, J = 1.2 Hz, 4 H), 5.17 (s, 4 H, CH2), 1.57 (s,30 H, C5Me5). ESI-MS (m/z): 991.6 [M – (PF6)2]+, 920.6 [M – (PF6)2 –Cl2]+, 919.5 [M – (PF6)2 – Cl2 – H]+.

Compound 10·(PF6)2: Yield: 117 mg, 62 %. Elemental anal. forC48H54Cl2F12N6P2Ir2: calcd. C 39.48; H 3.75; N 5.75 %; found: C40.05; H 3.97; N 5.43 %. IR (KBr): ν̃ = 1651 (νC=C); 1438 (νC=N); 843(νP–F) cm–1. 1H NMR (400 MHz, CDCl3): δ = 8.39 (d, J = 6.4 Hz, 4H), 8.12 (d, J = 6 Hz, 4 H), 7.86 (t, J = 7.2 Hz, 4 H), 7.19 (t, J =6.8 Hz, 4 H), 7.23 (d, J = 6 Hz, 4 H), 5.19 (s, 4 H, CH2), 1.63 (s, 30H, C5Me5). ESI-MS (m/z): 1169.8 [M – (PF6)2]+, 1098.2 [M – (PF6)2 –Cl2]+.

CCDC-813065 contains the supplementary crystallographic datafor complex 8. These data can be obtained free of charge viahttp://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cam-bridge Crystallographic Data Centre, CCDC, 12 Union Road,Cambridge CB2 1EZ, UK (Fax: 44-1223-336-033; or E-Mail:deposit@ccdc.cam.ac.uk).

AcknowledgementThe authors gratefully acknowledge financial support from the PriorityResearch Center Program (2009-0093825) and the Regional CoreCenter Program/ZEGVTRC (H369EB) through the National ResearchFoundation of Korea.

References[1] V. Balzani, A. Juris, M. Venturi, S. Campagna, S. Serroni, Chem.

Rev. 1996, 73, 759.[2] R. H. Holm, P. Kennepohl, E. I. Solomon, Chem. Rev. 1996, 73,

2239.[3] M. Albrecht, Chem. Rev. 2001, 78, 3457; C. Piguet, G. Bernardin-

elli, G. Hopfgartner, Chem. Rev. 1997, 74, 2005.[4] J.-C. G. Bünzli, C. Piguet, Chem. Rev. 2002, 79, 1897.[5] J. Canivet, L. Karmazin-Brelot, G. Süss-Fink, J. Organomet.

Chem. 2005, 690, 3202.[6] S. Ogo, T. Abura, Y. Watanabe, Organometallics 2002, 21, 2964.[7] S. Ogo, K. Uehara, T. Abura, Y. Watanabe, S. Fukuzumi, Organo-

metallics 2004, 23, 3047.[8] A. W. Stumpf, E. Saive, A. Demonceau, F. A. Noels, J. Chem.

Soc. Chem. Commun. 1995, 1127.[9] M. K. Tse, C. Döbler, S. Bhor, M. Klawonn, W. Mägerlein, H.

Hugl, M. Beller, Angew. Chem. Int. Ed. 2004, 43, 5255.[10] P. Gamez, P. de Hoog, O. Roubeau, M. Lutz, W. L. Driessen,

A. L. Spek, J. Reedijk, Chem. Commun. 2002, 1488.[11] W.-L. Jia, D.-R. Bai, T. McCormick, Q.-D. Liu, M. Motala, R.-

Y. Wang, C. Seward, Y. Tao, S. Wang, Chem. Eur. J. 2004, 10,994.

[12] C. Seward, J. Pang, S. Wang, Eur. J. Inorg. Chem. 2002, 1390.[13] Y. Kang, C. Seward, D. Song, S. Wang, Inorg. Chem. 2003, 42,

2789.[14] C. Seward, W.-L. Jia, R.-Y. Wang, G. D. Enright, S. Wang,

Angew. Chem. Int. Ed. 2004, 43, 2933.[15] Y. K. Yan, M. Melchart, A. Habtemariam, P. J. Sadler, Chem.

Commun. 2005, 4764, and references therein.[16] W. H. Ang, P. J. Dyson, Eur. J. Inorg. Chem. 2006, 4003, and

references therein.[17] B. Therrien, Coord. Chem. Rev. 2009, 253, 493.

Dinuclear Transition Metal Complexes with Dipyridylamine

[18] F. Marchetti, C. Pettinari, R. Pettinari, A. Cerquetella, A. Cingol-ani, E. J. Chan, K. Kozawa, B. W. Skelton, A. H. White, R.Wanke, M. L. Kuznetsov, L. M. D. R. S. Martins, A. J. L. Pom-beiro, Inorg. Chem. 2007, 46, 8245, and references therein.

[19] R. J. Restivo, G. Ferguson, J. Chem. Soc. Chem. Commun. 1973,847.

[20] C. J. Jones, J. A. McCleverty, A. S. Rothin, J. Chem. Soc. DaltonTrans. 1986, 109.

[21] S. Bhambri, A. Bishop, N. Kaltsoyannis, D. A. Tocher, J. Chem.Soc. Dalton Trans. 1998, 3379.

[22] G. Gupta, K. T. Prasad, B. Das, G. P. A. Yap, K. M. Rao, J. Or-ganomet. Chem. 2009, 694, 2618.

[23] K. T. Prasad, G. Gupta, A. K. Chandra, M. P. Pavan, K. M. Rao,J. Organomet. Chem. 2010, 695, 707.

[24] G. Gupta, B. Therrien, K. M. Rao, J. Organomet. Chem . 2010,695, 753.

[25] G. Gupta, G. P. A. Yap, B. Therrien, K. M. Rao, Polyhedron2009, 28, 844.

[26] G. Gupta, K. T. Prasad, B. Das, K. M. Rao, Polyhedron 2010, 29,904.

[27] G. Gupta, C. Zheng, P. Wang, K. M. Rao, Z. Anorg. Allg. Chem.2010, 636, 758.

[28] K. T. Prasad, G. Gupta, A. V. Rao, B. Das, K. M. Rao, Polyhe-dron 2009, 28, 2649.

[29] G. Gupta, K. T. Prasad, A. V. Rao, S. J. Geib, B. Das, K. M. Rao,Inorg. Chim. Acta 2010, 363, 2287.

[30] G. Gupta, S. Gloria, B. Das, K. M. Rao, J. Mol. Struct . 2010,979, 205.

[31] J. K. Hurst, Coord. Chem. Rev. 2005, 249, 313.[32] C. Sens, I. Romero, M. Rodriguez, A. Llobet, T. Parella, J. B.

Buchholz, J. Am. Chem. Soc. 2004, 126, 7798.[33] N. Goswami, R. Alberto, C. L. Barnes, S. Jurisson, Inorg. Chem.

1996, 35, 7546.

Z. Anorg. Allg. Chem. 2011, 1516–1521 © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.zaac.wiley-vch.de 1521

[34] R. Samanta, P. Munshi, B. K. Santra, N. K. Lokanath, M. A.Sridhar, J. S. Prasad, G. K. Lahiri, J. Organomet. Chem. 1999,579, 311.

[35] P. K. Santra, C. Sinha, W.-J. Sheen, F.-L. Liao, T.-H. Lu, Polyhe-dron 2001, 20, 599.

[36] A. K. Ghosh, K. K. Kamar, P. Paul, S.-M. Peng, G.-H. Lee, S.Goswami, Inorg. Chem. 2002, 41, 6343.

[37] C. Das, A. K. Ghosh, C.-H. Hung, G.-H. Lee, S.-M. Peng, S.Goswami, Inorg. Chem. 2002, 41, 7125.

[38] S. Jasimuddin, T. Mathur, C. Sinha, Inorg. Chim. Acta 2005, 358,3601.

[39] P. Didier, I. Ortmans, A. K. D. Mesmacker, R. J. Watts, Inorg.Chem. 1993, 32, 5239.

[40] B. P. Sulliran, D. J. Salmon, T. J. Meyer, Inorg. Chem. 1978, 17,3334.

[41] B. Antonioli, D. J. Bray, J. K. Clegg, K. Gloe, K. Gloe, O. Ka-taeva, L. F. Lindoy, J. C. Mc Murtrie, P. J. Steel, C. J. Sumby,M. Wenzel, Dalton Trans. 2006, 4783.

[42] M. A. Bennett, T. N. Huang, T. W. Matheson, A. K. Smith, Inorg.Synth. 1982, 21, 74.

[43] M. A. Bennett, T. W. Matheson, G. B. Robertson, A. K. Smith,P. A. Tucker, Inorg. Chem. 1980, 19, 1014.

[44] M. A. Bennett, A. K. Smith, J. Chem. Soc. Dalton Trans. 1974,233.

[45] J. W. Kang, K. Moseley, P. M. Maitlis, J. Am. Chem. Soc. 1969,91, 5970.

[46] C. White, A. Yates, P. M. Maitlis, Inorg. Synth. 1992, 29, 228.[47] G. M. Sheldrick, Acta Crystallogr. Sect. A 2008, 64, 112.[48] L. J. Farrugia, J. Appl. Crystallogr. 1997, 30, 565.

Received: April 5, 2011Published Online: June 28, 2011