~ Pergamon 0277-5387(95)00237-5

Polyhedron Vol. 15, No. 1, pp. 4348, 1996 Copyright © 1995 Elsevier Science Ltd

Printed in Great Britain. All rights reserved 0277 5387/96 $9.50+0.00

SYNTHESIS AND REDUCTION REACTION OF [SFeCoMo(CO)s(RCp)] [R = HCO (2), CHACO (3),

CzHsOCO (4)] CHIRAL CLUSTERS AND X-RAY CRYSTAL STRUCTURE OF [SFeCoMo(CO)s(C2HsOCOCp)] CLUSTER

WU HEPING and YIN YUANQI*

Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, P.R.C.

and

YANG QINGCHUAN

Chemistry Department of Beijing University, Beijing 100871, P.R.C.

(Received 22 November 1994 ; accepted 17 May 1995)

Abstract--The reaction of the [SFeCo2(CO)9 ] cluster 1 with [NaMo(CO)3(RCp)](2, R = HCO; 3, R = CH3CO ; 4, R = CzH5OCO) in THF gave [SFeCoMo(CO)8(RCp)] chiral clusters by a modification of the literature method. The clusters 2 and 3 were reduced to [SFeCoMo(CO)8(R'Cp)] [5, R' = H2C(OH) ; 6, R' = CHaCH(OH)] clusters by NaBH4 in methanol. The cluster 4 could not be reduced by NaBH4 and decomposed under the action of LiAIH4/A1C13. All clusters were characterized by C/H analysis, IR, IH NMR and a two-dimensional chemical shift correlated lH-13C NMR spectrum for cluster 3. The results showed that the metal fragment Co(CO)3 in SFeCo2(CO)9 could be exchanged by Mo(CO)2(RCp). An X-ray single crystal structure determination was made for the cluster 4.

Sodium salts of qS-cyclopentadienyl with or without substituent tricarbonyl derivatives of chromium, molybdenum and tungsten are important carbonyl transition metal compounds. A large number of carbonyl metal complexes have been derived from them. 1'2 Recently, considerable research has been focused on their basic reactions and photo- chemistry. 3

We have carried out the study on the metal ex- change reaction of the PhCCo3(CO)9 cluster with functionally substituted cyclopentadienyl tricar- bonyl derivatives of molybdenum and tungsten, using them as metal exchange reagents. In this paper, we report the preparation of [SFeCoMo (CO)s(RCp)] (2, R = HCO; 3, R = CH3CO; 4, R = C2H5OCO ) chiral clusters by the reaction of

* Author to whom correspondence should be addressed.

SFeCo2(CO)9 cluster with [NaMo(CO)3(RCp)] complexes and reductions of the clusters 2, 3 and 4.

RESULTS AND DISCUSSION

The cluster 1 was prepared by the reaction of $2Fe2(CO)6 with Co2(CO)8 in THF at room tem- perature using a modification of the method reported by Khattab and Marko. 6'v Refluxing a solution of [NaMo(CO)3(RCp)] with the cluster 1 in THF gave the black titled clusters 2 (30%), 3 (56%) and 4 (55%). Reduction of the clusters 2 and 3 by NaBH4 in methanol gave the clusters 5 (89%) and 6 (85%). However, we found that the cluster 4 could not be reduced by NaBH4 and was decomposed by LiAIH4/A1C13 in diethyl ether. This result shows that stronger reduction agent LiA1- H3/AIC13 can decompose the tetrahedral skeleton of the cluster SFeCoMo.

43

44 WU HEPING et al.

SFeCo2 (CO)9 + NaMo(CO)3 (RCp) , SFeC~oMo(CO)8 (RCp)

NaBH4/CHjOH

SFeCoMo(CO)8(R'Cp) R = HCO (2), CH3CO (3), C2H5OCO (4) ;

R' = H2C(OH) (5), CH~CH(OH) (6).

The C/H analyses, IR and ~H NMR spectra of all the clusters were consistent with the expected structure which is presented in Fig. 1. The IR spec- tra of all clusters exhibited a large number of CO absorption peaks between 2079 and 1876 cm-~ and the spectra of the clusters 5 and 6 revealed OH absorption peaks at 3383 and 3433 cm ~. These results are consistent with the reduction of the C-----O groups in the clusters 2 and 3 by the action of NaBH4. For IH NMR assignment of the clusters, chemical shifts of the substituted cyclopentadienyl in the clusters 2, 3 and 4 appeared at lower fields than in unsubstituted cyclopentadienyl, since ester and acetyl carbonyls are well known electron-with- drawing groups. However, it is curious that IH NMR spectra of 2 and 3 appeared as four asym- metric singlets at 5.570-5.599 ppm instead of two group triplets (A2B2 type). Four singlets should be two group symmetric doublets if the four singlets exhibited the existence of one pair of enantiomers of the chiral clusters. So we considered that the four singlets on the cyclopentadienyl should be con- tributed to differences of the chemical small environment of every proton on the cyclo- pentadienyl ring when Co(CO)3 in clusters 2 and 3 was displaced by Mo(CO)2(RCp). This deduction was confirmed by a IHJ3C-shift correlated NMR spectra of the cluster 3 (see Fig. 2), which indicated that every proton on the cyclopentadienyl is directly correlated to its carbon. Proton chemical shifts on the cyclopentadienyl in clusters 5 and 6 appeared

at higher field than that in the clusters 2 and 3. This is because shielding of substituent - - C H ( O H ) - - on the protons of cyclopentadienyl is larger than ~ O . Chemical shifts appearing at 2.150 and 2.113 were assigned to the protons of OH in the clusters 5 and 6, respectively. This result also demonstrates that ~ O on the cyclopentadienyl in the clusters 2 and 3 were transformed to OH by the action of NaBH4.

Tables 1 and 2 list the selected bond lengths and angles for the cluster 4. A diagram of the crystal structure is presented in Fig. 1. As seen in Fig. 1, the structure 4 (I) and (II) are two independent molecules that appear in the asymmeric unit. The cluster 4 has the tetrahedral skeleton composed of S, Fe, Co and Mo atoms. The Fe and Co atoms were coordinated by three two-electron carbonyl ligands. The Mo atom was coordinated by two two- electron carbonyl ligands and one five-electron car- bonylcyclopentadienyl ligand. The S atom is bonded to Co, Fe and Mo with S--Fe, S--Co and S--Mo bond lengths of 2.188, 2.200 and 2.37 ~, respectively. For the structure 4 (I) and (II), rel- evant bond angles among ligands and skeletal atoms are basically equal to each other. According to the literature, 8 the cluster SFeCoMo(CO)8Cp is monoclinic with space group P2~/n. There is one molecule in the asymmetric unit. However, for clus- ter 4, two molecules appear in the asymmetric unit. This result may be caused by the reduced symmetry of cluster 4 containing the C2H502C group, since the C2H502C group linked to cyclopentadienyl through

1~O(17) / ~ 1~:::~ O(8)

C ( 3 2 ) ~ O(12) O( 1~1 ) ~C(23) C(15)/ (~ C(16) O(2)~--~0~C(8) , Ct3D'~'/ ")8 O(19) ~ (/,'~ O(18) ~(, | O(10) "T

' I ~ ~ 0(20~ iff'~J,~) C(18) (~ [~C, ~ . ~ ) ' ~ ' ~ ' ~ ' ~ O(9)/'h /.~/~(~'~ __C(I) y Co(I)fq~ . . . . . W ~'~'1 ~C(17) f" |t', ° 'z )C(22)O(16){ "~ ~ Mo{ 1 )~ " / ' ~ :

c(25)fGc(29) . . . . 2 C(26, ~ ~ ~ O(14) C(10)~ ~'e"~C(12)S(I'~)

"N~.~ Fe(2) C(20) ~ _ k/~l

C(28) ~ C ( 9 ) C(II)

~ O ( 1 3 ) I II

Fig. 1. The molecular structure of the cluster 4.

~ 0(6)

)C(6)

to(5) C(5) C(4)

~ 0(4) Fe(I) ~

C(3)

~0(31

[SFeCoMo(CO)s(RCp)] chiral clusters

0 ppm

Fig. 2. 1H-~3C-shift correlated NMR spectrum of the cluster 3.

~6

I5.6

-5.7

-5.8 ~

-5.9

-6.0

45

Table 1. Selected bond angles (°)

4 (I) 4 (II) Co~Mo--Fe 54.6(1) 54.8(1) Co~Mo--S 49.7(1) 49.7(1) Fe--Mo--S 50.0(1) 50.1(1) Mo--Co--Fe 61.9(1) 61.8(1) Mo--Co---S 55.3(1) 55.1 (1) Fe--Co----S 54.4(1) 54.4(1) Mo---Fe---Co 63.5(1) 63.5(1) Mo----Fe--S 56.1(1) 55.9(1) Co---Fe--S 54.9(1) 54.8(1) Mo--S--Co 75.0(1) 75.1(1) Mo--S--Fe 73.9(1) 74.00) Co---S--Fe 70.0(1) 70.8(1)

O~C- -Mo ~ - - F e O---C--Co Ccp--Ccp--Ccp

168.6(6), 177.7(6) 178.3(7)-179.0(7) 178.4(6)-179.5(8) 106.6(6)-108.5(7)

C(13)--C(9)--C(14) 127.9(6) C(10)--C(9)---C(14) 123.5(6) C(9)--C(14)--O(9) 123.6(8) C(9)--C(14)---O(10) 110.6(7) O(9)--C(14)--O(10) 125.8(8)

169.7(5), 177.0(6) 177.9(7)-178.2(7) 178.2(6)-179.3(7) 107.0(6)-108.6(7)

C(29)--C(25)--C(30) C(26)--C(25)~C(30) C(25)--C(30)~O(9) C(25)--C(30)--O(20) O(19)---C(30)--O(20)

123.9(6) 128.3(6)

1123.8(8) 110.0(7) 126.2(8)

C - - C single bonds is located outside of the molec- ular skeleton and has a large degree of freedom.

From Table 2 the bond lengths of O(9)--C(14)

(1.188 .~), O(10)--C(14) (1.305 •) and O(10)--C(15) (1.428/~) in cluster 4 (I) exhibited successively the trend of the increase. This is also

46 WU HEPING et al.

Table 2. Selected bond lengths (/~)

4 (I) 4 (II)

Mo--Co 2.787(1) 2.785(1) Mo---Fe 2.745(1) 2.743(1) Co--Fe 2.538(1) 2.542(1)

Mo--C(CO) 1.999av 1.992av Fe--C(CO) 1.798av 1.800av Co--C(CO) 1.796av 1.801av

4 (1) 4 (II)

Mo--S 2.371(2) 2.363(2) Co--S 2.200(2) 2.199(2) Fe--S 2.187(2) 2.188(2)

( C - - O ) M o 1.126av 1.141av (C---O)Fe 1.130av 1.127av (C--O)co 1.130av 1.127av

Mo--Ccp 2.277(7)-2.375(6) 2.277(6) 2.386(7) Ccv--Ccv 1.389(10)-1.444(10) 1.385(10)-1.446(9)

1.483(17) O(9)--C(14) 1.188(10) 1.490(19) O(19)--C(30) 1.192(1) 1.428(11) 1.326(11)

C(9)--C(14) 1 .503 (11 ) C(15)--C(16) C(25)--C(30) 1 .492(11) C(31)--C(32) O(10)--C(14) 1 .305(11) O(10)--C(15) O(20)--C(30) 1 .326(11) O(20)--C(31)

the case for cluster 4 (II). This is due to the z-system of O(9)--C(15) and the large K-conjugate system composed of the lone-pair electrons of the O(10) atom and re-systems of O(9)--C(14) and cyclo- pentadienyl.

E X P E R I M E N T A L

All operations were carried out under nitrogen using standard Schlenk and vacuum techniques. N- Hexane and benzene were dried over sodium wire and distilled from sodium benzophenone under nitrogen. Tetrahydrofuran (THF) was dried over anhydrous P205 and distilled under nitrogen. Col- umn chromatography was carried out by using 160- 200 mesh silica gel.

Sodium formylcyclopentadienide, sodium ace- tylcyclopentadienide and sodium ethyl carbonyl- cyclopentadienide were prepared by literature methods.~'9 $2Fe2(CO)6 was prepared according to a literature procedure.~°

C/H analyses determination was performed using a 1106-type analyser ; 1R spectra were recorded on a Nicolet FT-IR 10DX IR spectrophotometer; ~H N MR and IH-13C N M R spectra were recorded on Bruker Am-400MHz spectrometer.

Synthesis

Preparation of SFeC02(CO)9 In a 50 cm 3 three- neck flask equipped with a condenser and nitrogen inlet and outlet valves were placed 82Fe2(CO)6 (1.00 g, 2.91 mmol), Co2(CO)8 (2.00 g, 5.85 mmol) and T H F (25 cm3). The mixture was stirred for 12 h at room temperature and T H F removed under

reduced pressure. The resulting residue was extracted with benzene and chromatographed on a 2.5 x 20 cm silica gel column. Elution of the column with benzene gave a brown band from which was obtained cluster 1 as a black solid (2.4 g, 90%). IR (KBr) : v2106m, 2065vs, 2034vs, 2023vs, 1977s and 1964s cm t.

Preparation of the clusters [SFeCoMo(CO)s (RCp)] [R = HCO (2), CH3CO (3), C2H5OCO (4)]. To a solution of sodium formylcyclopenta- dienide, NaCp(COH) (0.12 g, 0.90 mmol), in T H F (20 cm 3) was added Mo(CO)6 (0.24 g, 0.90 mmol). The mixture was refluxed for 16 h and cooled to room temperature. To this was added cluster I (0.33 g, 0.72 mmol). The mixture was refluxed for 2 h and T H F removed in vaeuo. The resulting residue was extracted by benzene (5 cm 3) and chro- matographed on a 2.5 x 20 cm silica gel column using benzene: hexane = 1 : 1. Chromatographic work-up gave three red fractions. Two fractions were the cluster SFeCoMo(CO)8Cp(trace) and the starting cluster 1. The third fraction was cluster 2. Product 2 was recrystallized in hexane/benzene at - 2 0 c ' C and gave a black compound (0.12 g, 30%). Found: C, 30.5; H 0.76. Calc. for C~4H5Co FeMoO9S: C, 30.0; H, 0.89%. IR (KBr disks): v1686m (C=O) , v2079s, 2031vs, 2008s, 1983s, 1950s, 1915m, 1881 m cm- ~ (terminal CO). ~HNMR (CDC13) :59.688 (s, 1H, HCO), 5.570-5.994 (q, 4H, C5H4).

Mo(CO)6 (0.19 g, 0.84 mmol) was added to a solution of sodium acetylcyclopentadienide (0.11 g, 0.84 mmol) NaCp(COCH3). After the mixture was refluxed for 14 h, to this was added SFeCo2(CO)9 (0.26 g, 0.56 mmol). Later operations were the same

[SFeCoMo(CO)8(RCp)] chiral clusters

as the above-mentioned. The column chro- matographic separation with hexane : ben- zene = 1:1 gave two red fractions. The first fraction is the cluster 1 and the second fraction is the cluster 3. Product 3 was recrystallized in hex- ane/benzene at - 20°C and gave black crystals (0.18 g, 56%). Found : C, 31.5 ; H, 1.3. Calc for C~sH7Co- FeMoO9S: C, 31.4; H, 1.2%. IR (KBr disks): v1688m (C~--~-O), v2076s, 2035vs, 2022s, 1998s, 1973s, 1954s, 1979m, 1876m cm -~ (terminal CO). ~H N M R (CDCI3): 62.426 (s, 3H, CH3), 5.584- 5.993 (q, 4H, C5H4).

Mo(CO)6 (0.27 g, 1.0 mmol) was added to a solution of sodium ethyl carbonylcyclopenta- dienide, NaCp(COzC2Hs) (0.19 g, 1.20 mmol), in DME (15 cm3). The mixture was refluxed for 5 h and removed DME in vacuo. The remaining residue was taken up in T H F (20 cm3). To this was added the starting cluster 1. Later operations were the same as the above-mentioned. Three red frac- tions were obtained by the column chro- matographic separation (benzene:hexane = 1:1). They are the starting material 1, by-product SFe CoMo(CO)sCp(trace) and the cluster 4. Cluster 4 was recrystallized in hexane/benzene at - 2Y~C and gave black crystalline (0.19 g, 43%). Found: C, 32.0; H, 1.4. Calc. for C~6H9CoFeMoO~0S : C, 31.8 ; H, 1.5%. IR (KBr disks) : v1723m ( ~ O ) , v2077vs, 2037vs, 2021vs, 2012vs, 1993vs, 1962s, 1904s cm -~ (terminal CO). ~H N M R (CDCI3) : 61.329 (t, 3H, CH3), 4.317 ( q, 2H, CHz), 5.427 5.981 (t, 4H, C51~4). 13C NMR(CDC13): 614.15 (s, CH3), 61.87 (s, CH2), 91.75-95.09 (m, C5H4), 162.79 (s, C~-----O), 210.42 (s, terminal CO).

The reduction of the clusters [SFeCoMo (CO)8(RCp)] ( R = H C O C H 3 C O ) by NaBH4. NaBH4 (15 mg, 0.4 mmol) was added to a solution of cluster 2 (400 rag, 0.7 mmol) in 95% CH3OH (9 cm3). The mixture was stirred for 5 h at room temperature. To this was added 10% HC1 (5 cm3), stirred and extracted twice with diethyl ether (40 cm3). The extracted solution was dried over anhy- drous MgSO4, filtered and the diethyl ether removed in vacuo. The crude product was extracted with benzene (5 cm 3) and chromatographed by a 10 × 2.5 cm silica gel column using elutuant (ben- zene : hexane = 1 : 3) to give one red fraction, from which was obtained [SFeCoMo(CO)8(CH2 (OH)Cp)] (0.36 g, 89%). Found: C, 29.6; H, 1.5. Calc. for CI4HTCoFeMoO98: C, 29.9; H, 1.2%. IR (KBr disks): v3383w (OH), v2074vs, 2025vs, 1977vs, 1885s cm -~ (terminal CO). ~H NMR(CDC13) : 62.150 (s, 1H, OH), 4.470 (s, 2H, C H 2 ) , 5.424 (s, 4H, C5H4).

NaBH4 (13 mg, 0.35 mmol) was added to a solu- tion of cluster 3 (380 mg, 0.66 mmol) in 95% meth-

47

anol (6 cm3). After the mixture was stirred for 5 h at room temperature, to this was added 10% HC1 (5 cm 3) and extracted twice with diethyl ether (40 cm3). The extracted solution was dried over anhy- drous MgSO4 overnight, filtered and solvent removed in vacuo. The remaining residue was extracted by benzene (5 cm 3) and chromatographed on a 10 × 2.5 cm silica gel column using elutuant (benzene : hexane = 1 : 3) giving one red fraction. This yielded the cluster [SFeCoMo(CO)8(CH3 CH(OH)Cp)] (6) as a black crystalline complex (0.33 g, 85%). Found: C, 31.7; H, 1.3%. Calc. for CIsH9CoFeMoO9S: C, 31.2; H, 1.6%. IR (KBr disks): v3433w (OH), v2074vs, 2023vs, 1985vs, 1888w cm ~ (terminal CO). ~H N M R (CDC13): 61.433 (s, 3H, CH3), 2.113 (s, IH, OH), 4.644 (s, 1H, CH), 5.265-5.474 (t, 4H, C5H4).

Crystallography of cluster 4

A black crystal was obtained from ben- zene/hexane at -20'~C. A crystal of ca 0.25 × 0.30 z 0.38 mm 3 was used for the structure determination. Data collection was performed at 23°C with Mo-K~ radiation (2 = 0.71073 ~) on a Siemens R3m/V diffractometer equipped with a graphite monochromator. A total of 7806 reflec- tions was collected in 3.0 ° ~< 20 >~ 48.0" by the co scan type, of which 5111 reflections with F > 4.0a(F) were considered to be observed.

The crystal is triclinic with space group Pi , empirical formula Cl6H9CoFeMoO10S, Mr = 604.0, a=8 .973(2) , b=10.120(3) , c=22.797(7) /~, c~ = 92.65(2), /~ = 90.00(2), 7 = 90-10(2) '~, V = 2067.8(10) ]k 3, Z = 4, Dc = 1.940 Mg m 3, /~ = 2.214 mm -~, F(000) = 1184, final R = 0.0385, Rw = 0.045.

The structure was solved by direct methods. Fourier and difference Fourier methods revealed all non-hydrogen atoms in chemically acceptable positions. All non-hydrogen atoms were refined with full-matrix least-squares and anisotropic ther- mal parameters.

From the structure analysis, it was difficult to distinguish Fe from Co atoms and these were found first by X-ray energy dispersive analysis. Co and Fe atoms in cluster 4 were located only by distance to the Mo atom, longer for Co and shorter for Fe atom. However, it is not certain that the positioning of the two atoms is unique and they may exchange with each other since their coordination and chemi- cal bond lengths are very similar.

Acknowledgement--This work was supported by State Key Laboratory of Coordination Chemistry, Nanjing University.

48 WU HEPING et al.

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