synthesis, characterization, and x-ray structures of ru 3 (co) 9 (dotpm)(l) complexes [l = pph 3 ,...

Job/Unit: Z14164 /KAP1 Date: 28-07-14 10:45:12 Pages: 7

ARTICLE

DOI: 10.1002/zaac.201400164

Synthesis, Characterization, and X-ray Structures of Ru3(CO)9(dotpm)(L)Complexes [L = PPh3, P(C6H4Cl-p)3, and PPh2(C6H4Br-p)]

Siti Syaida Sirat,[a] Imthyaz Ahmed Khan,[b] Omar Bin Shawkataly,*[a] andMohd Mustaqim Rosli[c]

Keywords: Triruthenium cluster; Crystal structure; Phosphine ligands; dotpm; NMR spectroscopy; X-ray diffraction

Abstract. The reaction of Ru3(CO)10(dotpm) (1) [dotpm = (bis(di-ortho-tolylphosphanyl)methane)] and one equivalent of L [L = PPh3,P(C6H4Cl-p)3 and PPh2(C6H4Br-p)] in refluxing n-hexane afforded aseries of derivatives [Ru3(CO)9(dotpm)L] (2–4), respectively, in ca.67–70% yield. Complexes 2–4 were characterized by elemental analy-sis (CHN), IR, 1H NMR, 13C{1H} NMR and 31P{1H} NMR spec-

Introduction

The formation and reactivity of Ru3(CO)12 containing group15 ligands has led to development of the trinuclear clustercarbonyl chemistry.[1–3] It has long been thought that the stericand electronic effects of group 15 ligand contribute to thechanges in the metal-metal framework.[4] For example,Ru3(CO)9(dppm)(L) [L = monodentate group 15 ligands] havebeen studied in great detail.[5–10] It was reported that variationsin the Ru–Ru bond adjacent to the phosphine ligand enhancedthe reactivity of Ru3(CO)10(dppm) over its parent compoundRu3(CO)12 because Ru3(CO)10(dppm) is unable to effectivelyrelieve steric congestion imposed by the dppm ligand.[6] Thebridging small bite angle of dppm ligand activated the clusterto further substitutions and also maintain the stability and in-tegrity of the triruthenium metal cluster framework.[11] On theother hand, the bis(di-ortho-tolylphosphanyl)methane (dotpm)is a bidentate ligand, which has similar structure to bis(diphen-ylphosphanyl)methane (dppm), but consists of one ortho-methyl group on each benzene ring resulting in greater stericcrowding as compared to dppm. Similar to dppm, the stabilityof dotpm is also conferred via the formation of stable five-membered ring resulting in the tendency to bridge two metalatoms.[12] Besides, the dotpm ligand also function as an excel-

* Prof. Dr. O. B. ShawkatalyFax: +604-6576000E-Mail: [email protected]

[a] Chemical Sciences ProgrammeSchool of Distance EducationUniversiti Sains Malaysia11800 USM, Penang, Malaysia

[b] Department of ChemistryGokhale Centenary CollegeAnkola 581314, NK, Karnataka, India

[c] X-ray Crystallography UnitSchool of Physics, Universiti Sains Malaysia11800 USM, Penang, Malaysia

Z. Anorg. Allg. Chem. 0000, �,(�), 0–0 © 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1

troscopy. The molecular structures of 2, 3, and 4 were established bysingle-crystal X-ray diffraction. The bidentate dotpm and monodentatephosphine ligands occupy equatorial positions with respect to the Rutriangle. The effect of substitution resulted in significant differences inthe Ru–Ru and Ru–P bond lengths.

lent chelating ligand for low-valent mononuclear com-plexes.[13] Previously, the structure of Ru3(CO)10(dotpm)[12]

and its derivatives with PPh2(CH2SPh) (7),[14] P(OC6H5)3

(6),[15] and P(OCH2CH2Cl)3 (5)[16] have been reported.Thus, it is clear that Ru3(CO)10(dotpm) could overcome its

steric crowding without the breaking of the metal–metal bondsand favorable to carbonyl loss. In order to confer similar sta-bility onto a trinuclear core of Ru3(CO)10(dotpm), the PPh3,P(C6H4Cl-p)3, and PPh2(C6H4Br-p) were chosen as ligand tocover a pattern of substitutions and of electronic and stericproperties. Furthermore, the PR3 ligands were chosen as sub-stituents in this area of study because the steric and electronicproperties are controlled by the nature of the R group bondedto the phosphorus atom.[17,18] In this report, a similar route wasused to synthesize three new trisubstituted clusters and theirstructures were compared with previous reported structures.Besides, the study also focuses on the effect of different group15 ligands toward Ru–Ru and Ru–P bond lengths. In continua-tion of the research on substituted triruthenium clusters, thesynthesis, characterization, and crystal structures ofRu3(CO)9(dotpm)PPh3 (2), Ru3(CO)9(dotpm)P(C6H4Cl-p)3

(3), and Ru3(CO)9(dotpm)PPh2(C6H4Br-p) (4) are reportedherein.

Results and Discussion

Synthesis and Characterization

The IR spectrum in the carbonyl region is similar to that ofother previously reported trisubstituted derivatives of the typeRu3(CO)9(LL)PR3 [LL = bidentate ligand], indicating that theyare isostructural.[6,8] The multiplet signal observed between δ= 7.59–7.01 ppm in the 1H NMR spectrum of compounds 2,3, and 4 is characteristic of phenyl groups. The triplet signalsat δ = 4.45 (2) and 4.42 ppm (3 and 4) can be assigned to the


O. B. Shawkataly et al.ARTICLEmethylene proton of the dotpm ligand, while the singlet signalof the methyl proton was observed at δ = 1.8 ppm. The13C{1H} NMR spectra for compounds 2, 3, and 4 are showedsignals for CO around δ = 212.7, 212.2, and 212.5 ppm,respectively. The signals of the carbon atoms of the phenylrings are observed in the range of δ = 136.5–126.4 ppm.

The signal of the methylene carbon of dotpm ligands is ob-served at δ = 41.7 (2) and 31.6 (3) ppm, and the signal of themethyl carbon at δ = 21.6 (2), 22.7 (3), and 21.7 (4) ppm. The31P{1H} NMR spectrum of the dotpm ligand showed a broadsinglet signal at δ = 12.8 (2), 12.7 (3), and 12.8 ppm (4), whichis slightly shifted downfield to that of the dotpm ligand in theparent compound 1 (δ = 11.0 ppm). The broad singlet signalof the 31P{1H} NMR spectrum for the dotpm ligand can beobserved probably because of a fluxional process by inter-changing two P atoms of the dotpm ligand. The 31P{1H} NMRsignals for PPh3, P(C6H4Cl-p)3, and PPh2(C6H4Br-p) are ob-served at δ = 33.9, 34.3, and 35.1 ppm, respectively.

X-ray Crystal Structure Analysis

The crystal structures of 2, 3, and 4 were determined. Crys-tal data and experimental details of the structure determi-nations are listed in Table 1. The selected bond lengths of com-pounds 2, 3, and 4 are shown in Table 2, whereas selectedbond angles and torsion angles are shown in Table 3. Thestructures of compounds 2, 3, and 4 show the common triangu-lar arrangement of the three Ru atoms. Each Ru atom carriesone equatorial and two axial terminal carbonyl ligands. TheORTEP diagrams of 2, 3, and 4 are shown in Figure 1, Fig-ure 2, and Figure 3, respectively. The Ru–Ru separations in 2,

Table 1. Crystal data and structure refinement for compounds 2, 3, and 4.

2 3 4

Empirical formula C57H47O9P3Ru3,CH2Cl2 4(C56H42Cl3O9P3Ru3),(C6H14) C56H44BrO9P3Ru3,CHCl3Formula weight 1357.00 5531.65 1456.15Temperature /K 100 100 100λ /Å 0.71073 0.71073 0.71073Crystal system monoclinic orthorhombic triclinicSpace group C2/c Fdd2 P1̄Unit cell dimensionsa /Å 45.3256(14) 35.1947(17) 11.9924(7)b /Å 11.5258(3) 62.462(3) 14.7716(9)c /Å 22.9933(7) 11.3094(6) 18.3722(11)α /° 90 90 104.308(1)β /° 108.317(1) 90 108.540(1)γ /° 90 90 95.038(1)V /Å3 11403.4(6) 24862(2) 2940.5(3)Z 8 4 2Dcalc /Mg·m–3 1.581 1.478 1.645F(000) 5440 11048 1444Absorption coefficient /mm–1 1.017 0.976 1.711Crystal size /mm 0.15�0.19�0.43 0.06� 0.53�0.63 0.10�0.12�0.55θ Range /° 2.3–30.0 2.3–30.0 1.8–30.1Reflections collected / unique 97369/ 16550 45382/17264 45886/17136Rint 0.037 0.032 0.027Data/restrains/parameters 16550/0/683 17264/1/698 17136/189/717Goodness-of fit on F2 1.05 1.05 1.02R 0.0238 0.0313 0.0326Rw 0.0575 0.0842 0.0941Largest difference in peak and hole /e·Å–3 –0.43 and 0.92 –0.97 and 0.85 –1.76 and 2.50

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3, and 4 are in the range of 2.8345(2)–2.8803(2) (for 2),2.8547(3)–2.8750(3) (for 3) and 2.8533(3)–2.8948(3) Å (for4). These values are similar to those found for other analogouscomplexes and the values are also comparable to the Ru–Ruseparations in Ru3(CO)10(dotpm) [2.8280(3)–2.8420(3) (mole-cule A), 2.8442(3)–2.8554(3) Å (molecule B)],[12] andRu3(CO)12 [2.8512(4)–2.8595(4) Å].[19] The position of thelongest Ru–Ru bond for clusters 2, 3, and 4 is cis to the mono-dentate phosphine ligand as a result of steric interactions be-tween group 15 ligands and the CO group cis to it on theadjacent metal atom.[4] The series of studies on the effect ofgroup 15 ligands towards transition metal clusters have shownthat there is some lengthening of the metal–metal bond cis tothe substituents.[20–22] Similar observations were also seen inRu3(CO)9(dppm)(PR3) where R = Ph, Cy, iPr, Et.[6] The dotpmligand bridges Ru1 and Ru2 both in equatorial positions. TheRu1–P1/Ru2–P2 distances for 2, 3, and 4 are between2.3397(4) and 2.3581(7) Å. As expected, the monodentatephosphine ligands PPh3, P(C6H4Cl-p)3, and PPh2(C6H4Br-p)are also coordinated at equatorial positions. The Ru3–P3 bondlength for compounds 2 [2.3308(5) Å], 3 [2.3418(8) Å] and 4[2.3399(7) Å] is slightly similar and significantly differentfrom those in 5 [2.2543(5) Å] and 6 [2.2488(5) Å]. Apparently,this bond length is controlled by the cone angle and donicityof the ligands.[4,6,23] According to the QALE analysis[24] of thephosphorus ligands used in this study, P(C6H4Cl-p)3 possessesbetter σ-donors (donicity value = 16.8) than PPh3 (donicityvalue = 13.25) with a similar size of cone angle but in thesecomplexes the Ru3–P3 bonds are only slightly affected(0.011 Å).


Ru3(CO)9(dotpm)(L) Complexes [L = PPh3, P(C6H4Cl-p)3, PPh2(C6H4Br-p)]

Table 2. Selected bond lengths /Å in Ru3(CO)9(dotpm)(L) complexes.

L Com- P1P2 Cone Ru–Ru Ru1–P1 Ru2–P2 Ru3–P3 Ru–COaxa) Ru–COeq

b) Ref.pound angle/ ° a b c

CO f) 1 dotpm 90 2.8350(2) 2.8280(3) 2.8420(3) 2.4351(7) 2.3422(7) 1.906(3) 1.9372 1.9045 c) [12]2.8429(3) 2.8442(3) 2.8554(3) 2.3450(7) 2.3459(7) 1.909(3) 1.9372 1.9053 c)

PPh3 2 dotpm 145 2.8345(2) 2.8457(2) 2.8803(2) 2.3397(4) 2.3519(4) 2.3308(5) 1.9329 1.8901 e)

P(C6H4Cl-p)3 3 dotpm 145 2.8547(3) 2.8634(3) 2.8750(3) 2.3520(8) 2.3560(8) 2.3418(8) 1.9338 1.8927 e)

PPh2(C6H4Br-p) d) 4 dotpm 2.8621(3) 2.8948(3) 2.8533(3) 2.3484(6) 2.3581(7) 2.3399(7) 1.9352 1.8927 e)

P(OCH2CH2Cl)3d) 5 dotpm 110 2.8492(2) 2.8614(2) 2.8415(2) 2.3483(5) 2.3462(5) 2.2543(5) 1.9340 1.8883 [16]

P(OC6H5)3d) 6 dotpm 128 2.8557(2) 2.8510(2) 2.8473(2) 2.3476(5) 2.3538(5) 2.2488(5) 1.9354 1.8931 [15]

PPh2(CH2SPh) 7 dotpm 2.8449(7) 2.8352(6) 2.8744(6) 2.3594(11) 2.3476(11) 2.3289(12) 1.9292 1.8863 [14]

a) Average of six. b) Average of three, except for: c) Average of four. d) Read P3 at Ru3 as COeq. e) This work. f) Values for two independentmolecules.

Table 3. Selected bond angles /° and torsion angles /° for complexes2, 3, and 4.

2 3 4

Bond anglesRu2–Ru1–Ru3 59.72(1) 59.97(1) 60.86(1)Ru1–Ru2–Ru3 60.94(1) 60.37(1) 59.42(1)Ru1–Ru3–Ru2 59.34(1) 59.67(1) 59.72(1)Ru1–Ru2–P2 95.73(1) 92.18(2) 92.00(2)Ru2–Ru1–P1 90.95(1) 92.06(2) 91.87(2)Ru1–Ru3–P3 109.78(1) 102.41(2) 164.46(2)Ru3–Ru2–P2 154.69(1) 151.08(2) 150.50(2)Ru1–C30–O1 172.62(15) 173.9(3) 179.1(2)Ru1–C32–O3 171.68(15) 172.2(3) 173.5(2)Ru2–C33–O4 175.00(17) 172.9(3) 179.0(2)Ru2–C35–O6 172.07(16) 171.9(3) 173.8(2)Ru3–C36–O7 174.38(15) 171.4(3) 177.3(3)Ru3–C38–O9 172.89(16) 172.5(3) 173.0(2)Ru1–C31–O2 176.01(16) 178.9(3) 173.5(2)Ru2–C34–O5 176.23(16) 178.9(3) 171.5(2)Ru3–C37–O8 176.67(17) 177.0(3) 173.3(2)C30–Ru1–C32 175.92(7) 172.31(13) 173.54(11) a)

C33–Ru2–C35 174.12(8) 174.65(13) 171.79(11) b)

C36–Ru3–C38 171.69(7) 176.31(17) 177.95(11) c)

Torsion anglesP3–Ru3–Ru1–P1 –161.16(2) 153.23(4) 64.50(8)P3–Ru3–Ru2–P2 32.79(7) –25.11(9) –155.15(4)P1–Ru1–Ru2–P2 19.04(1) –22.03(2) 22.71(2)P3–Ru3–Ru2–C34 –156.36(8) 168.9(1) 12.69(8) d)

C37–Ru3–Ru2–C34 20.40(8) –15.4(1) 103.4(1) d)

Ru2 –Ru1–P1–C13 –32.12(6) 22.0(1) –29.29(2)Ru1–Ru2 –P2–C13 –3.97(6) 22.2(1) –15.90(9)

a) Read C30 as C31. b) Read C33 as C34. c) Read C36 as C37.d) Read C34 as C33.

This is probably due to a slight distraction of the covalentradius of the phosphorus as the pendent groups on the phos-

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Figure 1. ORTEP diagram of Ru3(CO)9(dotpm)PPh3 (2) with 50%probability of ellipsoids for non-H atoms. The solvent is omitted forclarity.

phorus become more electronegative. The corresponding don-icity value of P(OCH2CH2Cl)3 (20.4) and P(OC6H5)3 (23.6) incompounds 5 and 6, respectively are better than the donicityvalue of PPh3 (13.25).[24] The Ru3–P3 bonds in compounds 5and 6 are slightly lower as compared with the Ru3–P3 bondin 2, which can be a consequence of the smaller cone anglesof P(OCH2CH2Cl)3 (110°) and P(OC6H5)3 (128°). To the bestof our knowledge, there is no reported cone angle and σ-donorability for PPh2(C6H4Br-p), but based on Ru3–P3 bond lengthin 4, the cone angle probably is almost similar withP(C6H4Cl-p)3 and PPh3. The Ru–CO axial bonds are longer


O. B. Shawkataly et al.ARTICLE

Figure 2. ORTEP diagram of Ru3(CO)9(dotpm)P(C6H4Cl-p)3 (3) with50% probability of ellipsoids for non-H atoms. The solvent is omittedfor clarity.

Figure 3. ORTEP diagram of Ru3(CO)9(dotpm)PPh2(C6H4Br-p) (4)with 50% probability of ellipsoids for non-H atoms. The solvent isomitted for clarity.

than those of the Ru–CO equatorial bonds and the trend issimilar in 2–4 and also Ru3(CO)10(dotpm).[12] The angles ofeach C–Ru–C at the axial position of compound 4 are in therange [171.79(11)–177.95(11)°] as compared to compounds 3[172.31(13)–176.31(17)°] and 2 [171.69(7)–175.92(7)°]. Asexpected, the equatorial Ru–C–O bond angles for these com-plexes are almost linear [176.01(16)–176.67(17) (2), 177.0(3)–178.9(3) (3), and 177.3(3)–179.1(2)° (4)] compared to the ax-ial Ru–C–O bond angles [171.68(15)–175.0(17) (2), 171.4(3)–173.9(3) (3), and 171.5–173.8(2)° (4)].

The distortion of axial Ru–C–O bond angles is due to thevan der Waals repulsions between the axial oxygen atom, asseen in Ru3(CO)12.[19] The strength of the chelated ring be-tween dotpm [Ru3(CO)9(dotpm)PPh3 (2)] and dppm[Ru3(CO)9(dppm)PPh3] is shown in the intracyclic metal–metal–ligand angles. The Ru2–Ru1–P1 [90.95(1)°] and Ru1–Ru2–P2 [95.73(1)°] angles of Ru3(CO)9(dotpm)PPh3 are al-


most similar to Ru2–Ru1–P1 [90.93(5)°] and Ru1–Ru2–P2[94.97(5)°] of Ru3(CO)9(dppm)PPh3.[6] Thus, this results inthe bidentate ligand bridging the shortest Ru–Ru bond. Theshortest Ru–Ru bond length in Ru3(CO)9(dotpm)PPh3

[2.8345(2) Å] is almost similar to corresponding bonds inRu3(CO)9(dppm)PPh3 [2.835(1) Å][6] and Ru3(CO)9(dppm)-AsPh3 [2.8461(7) Å].[25] As reported, the strength ofthe chelated ring in dppm ligands is also shown inRu3(CO)10(dppm).[26] Obviously, the strength of a chelatedring in dotpm ligand is almost similar to dppm ligand in con-sideration with similar ligand substitution. A different observa-tion is seen in compounds 3 and 4, in which the intracyclicmetal–metal–ligand angles are smaller than the correspondingvalues in Ru3(CO)9(dotpm)PPh3. This is expected because ofthe effect of different substitution on the Ru3 atom. The corre-lation between intracyclic Ru–Ru–L angles and the corre-sponding Ru–Ru bond lengths are well explained by Bonnetand co-workers.[26] The torsion angles [P1–Ru1–Ru2–P2] ofcompounds 2, 3, and 4 are 19.04(1), –22.03(2), and 22.70(2)°,respectively. Thus, two P atoms in dotpm are slightly out ofthe triruthenium plane, forcing one below and the other abovethe plane.

Figure 4, Figure 5, and Figure 6 represent the crystal pack-ing for compounds 2, 3, and 4, respectively. Table 4 representthe hydrogen bond arrangement. The intermolecular interac-tion of C16–H16A···O6 in compound 2 are linked together twoset of molecules to form a dimer, while in compound 3, themolecules are link together by intermolecular interactions ofC5–H5A···O3, to form an infinite one-dimensional chain alongthe [0 1 –1] direction. In compound 4, intermolecular interac-tions of C5–H5A···O6 form a dimer. The set of moleculesformed by this dimer is further connected into infinite chainsalong [1 0 0] direction.

Figure 4. Crystal packing for compound 2.



Table 4. Hydrogen-bond arrangement /Å,° for 2, 3, and 4.

Atoms, D–H···A Distance D–H Distance H···A Distance H···A Angle D–H···A

2 C16–H16A···O6I 0.93 2.50 3.222(3) 1353 C5–H5A···O3II 0.93 2.56 3.420(4) 1544 C5–H5A···O6III 0.95 2.54 3.400(3) 151

C53–H53A···O3IV 0.95 2.45 3.188(4) 135

Symmetry codes: I = –x, y, –z+1/2; II = x+1/4, –y+3/4, z–1/4; III = –x+2, –y, –z; IV = x–1, y, z.



Conclusions

Ru3(CO)9(dotpm)PPh3 (2), Ru3(CO)9(dotpm)P(C6H4Cl-p)3

(3), and Ru3(CO)9(dotpm)PPh2(C6H4Br-p) (4) were synthe-sized and structurally characterized. The dotpm ligand servesto maintain the integrity of the trinuclear framework. TheRu–Ru and Ru–P bond lengths of compound 2, 3, and 4 wereanalyzed and the results compared with those reported forthe clusters Ru3(CO)9(dotpm)(L) [L = P(OCH2CH2Cl)3,P(OC6H5)3, PPh2(CH2SPh)] and its parent compound,Ru3(CO)10(dotpm). The Ru–Ru bonds that are cis to the mono-dentate phosphine ligands are longer than the other Ru–Ru dis-tances in triruthenium clusters [except when L = P(OC6H5)3]


while the Ru3–P3 bond lengths are increasing in the order ofP(OC6H5)3 � P(OCH2CH2Cl)3 � PPh2(CH2SPh) � PPh3 �PPh2(C6H4Br-p) � P(C6H4Cl-p)3. Indeed, the Ru3–P3 bondlengths are governed by both steric and electronic (donicity)of the P-donor ligand and usually it is the combination of bothof these effects.

Experimental Section

The reactions were conducted in high purity nitrogen atmospheresusing standard Schlenk technique. Hydrocarbon solvents were driedwith sodium metal. Commercial Ru3(CO)12, PPh3, P(C6H4Cl-p)3, andPPh2(C6H4Br-p) were used without further purification, while dotpmwas prepared by lithiation method.[13] Ru3(CO)10(dotpm) was preparedusing the sodium benzophenone ketyl radical.[27] Elemental analysiswas performed with a Perkin-Elmer model 2400 LS Series II C, H,N analyzer, USA. The 1H, 13C{1H} and 31P{1H} NMR spectra wereperformed with a Bruker Ascend 500 MHz spectrometer. The 1H and13C{1H} NMR shifts were referenced to TMS and 31P{1H} NMR shiftswere referenced to 85% H3PO4. Solution infrared spectra wereacquired with a Perkin-Elmer System 2000 FTIR spectrometer. Prepar-ative Thin Layer Chromatography (TLC) was performed on glassplates (20�20 cm) coated (0.5 mm) with Silica Gel (Merck, 60GF254).The melting points of the compounds were recorded in open capillariesusing an SMP1 UK melting point apparatus.

Synthesis of Ru3(CO)9(dotpm)PPh3 (2): A mixture ofRu3(CO)10(dotpm) (100 mg, 0.976 mmol) and PPh3 (25.6 mg,0.976 mmol) was refluxed in n-hexane (25 mL) for 1 h. Completionof the reaction was monitored by TLC. The solvent was removed underreduced pressure and was separated by preparative TLC. PreparativeTLC (2:3 dichloromethane:n-hexane) afforded three bands. The firstband (Rf = 0.80) gave the starting material Ru3(CO)10(dotpm) and thesecond band (Rf = 0.76) gave the major product characterized asRu3(CO)9(dotpm)PPh3, and the third band was too small for furthercharacterization. Yield: 86.3 mg (70.21%). Melting point: 175 °C.C58H49Cl2O9P3Ru3: calcd. C 51.33; H 3.64%; found: C 51.25; H3.50%. IR (cyclohexane): ν(CO): 2059 s, 2042 w, 2017 w, 1989br·cm–1. 1H NMR (CDCl3): δ = 7.48–7.03 (m, 31 H, Ph), 4.45 (t, 2 H,2JPH = 8.75 Hz, PCH2P), 1.8 (s, 12 H, CH3). 13C{1H} NMR (CDCl3): δ= 212.7 (CO), 134.1–126.4 (Ph), 41.7 (CH2), 21.6 (CH3). 31P{1H}NMR (CDCl3): δ = 33.9 (s, PPh3), 12.8 (br., dotpm). Single crystalssuitable for X-ray crystallography were grown by solvent/solvent dif-fusion of methanol/dichloromethane at 10 °C.

Synthesis of Ru3(CO)9(dotpm)P(C6H4Cl-p)3 (3): A mixture ofRu3(CO)10(dotpm) (100 mg, 0.976 mmol) and P(C6H4Cl-p)3 (35.7 mg,0.976 mmol) was refluxed in n-hexane (25 mL) for 1 h. Completionof the reaction was monitored by TLC. The solvent was removed underreduced pressure and was separated by preparative TLC. PreparativeTLC (2:3 dichloromethane:n-hexane) afforded three bands. The firstband (Rf = 0.80) gave the starting material Ru3(CO)10(dotpm) and thesecond band (Rf = 0.70) gave the major product characterized asRu3(CO)9(dotpm)P(C6H4Cl-p)3, and the third band was too small for


O. B. Shawkataly et al.ARTICLEfurther characterization. Yield: 94.2 mg (70.89%). Melting point:170 °C. C58H46Cl3O9P3Ru3: calcd. C 49.93; H 3.35%; found: C 49.86;H 3.56 %. IR (cyclohexane): ν(CO): 2059 s, 2042 w, 2018 w, 1989 brcm–1. 1H NMR (CDCl3): δ = 7.59–7.01 (m, 28 H, Ph), 4.42 (t, 2 H,2JPH = 9.2 Hz, PCH2P), 1.8 (s, 12 H, CH3). 13C{1H} NMR (CDCl3):δ = 212.2 (CO), 136.5–128.7 (Ph), 31.6 (CH2), 22.7 (CH3). 31P{1H}NMR (CDCl3): 34.3 [s, P(C6H4Cl-p)3], 12.7 (br., dotpm). Single crys-tals suitable for X-ray crystallography were grown by solvent/solventdiffusion of chloroform/n-hexane at 10 °C.

Synthesis of Ru3(CO)9(dotpm)PPh2(C6H4Br-p) (4): A mixture ofRu3(CO)10(dotpm) (100 mg, 0.976 mmol) and PPh2(C6H4Br-p)(33.2 mg, 0.976 mmol) was refluxed in n-hexane (25 mL) for 1 h.Completion of the reaction was monitored by TLC. The solvent wasremoved under reduced pressure and was separated by preparativeTLC. Preparative TLC (2:3 dichloromethane:n-hexane) afforded threebands. The first band (Rf = 0.80) gave the starting materialRu3(CO)10(dotpm) and the second band (Rf = 0.75) gave the majorproduct characterized as Ru3(CO)9(dotpm)PPh2(C6H4Br-p) and thethird band was too small for further characterization. Yield: 88.5 mg(67.82%). Melting point: 165 °C. C57H45BrCl3O9P3Ru3: calcd. C47.01; H 3.11%; found: C 47.47; H 3.59%. IR (cyclohexane): ν(CO):2058 s, 2042 w, 2030 w, 1999 m, 1982 br·cm–1. 1H NMR (CDCl3): δ= 7.48–7.02 (m, 30 H, Ph), 4.42 (t, 2 H, 2JPH = 9.0 Hz, PCH2P).13C{1H} NMR (CDCl3): δ = 212.5 (CO), 135.7–128.3 (Ph), 21.7(CH3). The broad singlet of 31P{1H} NMR spectrum for the dotpmligand probably because fluxional process by interchanging two Patoms of dotpm. 31P{1H} NMR (CDCl3): 35.1 [t, 3JPP = 9.8 Hz,PPh2(C6H4Br-p], 12.8 (br., dotpm). Single crystals suitable for X-raycrystallography were grown by solvent/solvent diffusion of methanol/dichloromethane at 10 °C.

X-ray Structural Determination: Data collection and determinationof cell parameters was carried out at 100.0(1) K with the OxfordCryosystem Cobra low-temperature attachment with Mo-Kα radiation(λ = 0.71073 Å) with a Bruker SMART APEX-II CCD area-detectordiffractometer equipped with a graphite monochromator. The data wasreduced using SAINT.[28] A semi-empirical absorption correction wasapplied to the data using SADABS.[28] The structure was solved bydirect methods and refined against F2 by full-matrix least-squaresusing SHELXTL.[29] For compound 2 and 4, a region of disorderedelectron density, most probably disordered dichloromethane solventmolecules, was treated with the SQUEEZE routine in PLATON.[30] Incompound 4, the bromophenyl and phenyl groups are disordered overtwo positions with the final refine occupancy of 0.9395(11):0.0605(11). The phenyl ring for the minor part was refined with rigidgroup restraints. Similar and rigid bond restraints were also used fordisordered component.

Crystallographic data (excluding structure factors) for the structures inthis paper have been deposited with the Cambridge CrystallographicData Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK. Copiesof the data can be obtained free of charge on quoting the depositorynumbers CCDC-974596 for Ru3(CO)9(dotpm)PPh3 (2), CCDC-974594, for Ru3(CO)9(dotpm)P(C6H4Cl-p)3 (3), and CCDC-974595for Ru3(CO)9(dotpm)PPh2(C6H4Br-p) (4) (Fax: +44-1223-336-033;E-Mail: [email protected], http://www.ccdc.cam.ac.uk).

AcknowledgementsOBS would like to thank Universiti Sains Malaysia (USM) for theResearch University Grant 1001/PJJAUH/811188. IAK thanks USMfor a Visiting Researcher position. SSS thanks USM for the ResearchAssistant position.


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Received: April 11, 2014Published Online: �



S. S. Sirat, I. A. Khan, O. B. Shawkataly,*M. M. Rosli ....................................................................... 1–7

Synthesis, Characterization, and X-ray Structures ofRu3(CO)9(dotpm)(L) Complexes [L = PPh3, P(C6H4Cl-p)3,and PPh2(C6H4Br-p)]


synthesis, characterization, and x-ray structures of ru 3 (co) 9 (dotpm)(l) complexes [l = pph 3 ,...

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