Organometallics 1995, 14, 2115-2118
2115
Synthesis and Structural Characterization of the Heterometallic Clusters CpCoFe&~-Se)2(C0)6 and CpCoFedp3-S)@a-Se)(CO)s Pradeep Mathur,*Ja P. Sekar,la and C. V. V. Satyanarayanalb Chemistry Department and Regional Sophisticated Instrumentation Center, Indian Institute of Technology, Powai, Bombay 400 076, India
Mary F . Mahon School of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K. Received November 17, 1994@ Summary: The heterometallic clusters CpCoFeZ(p3-Se)z(2) were pre(COh (1) and C~COF~Z(~~-S)(~~-S~)(CO)~ pared i n moderate yield from the room-temperature reaction of the mixed-chalcogenide compound (CO)$ez(p-SSe)with fieshly prepared C~CO(CO)S. Both clusters were characterized by elemental analysis, IR, and IH, 13C,and 77SeN M R as well as X-ray diffractionanalysis. Compound 1 crystallized i n the triclinic space group P i , with a = 6.638(1) A, b = 14.675(4) A, c = 17.844(7) A, a = 111.37(3)", ,6 = 100.80(2)0, y = 89.88(2)", V = 1585.9 A3, Z = 4, D, = 2.35 g ~ m -R~=, 3.85%, and R, = 3.12%. Compound 2 crystallized in the monoclinic s ace group C2Ic with a = 34.994(10) A, b = 6.599(2) c = 14.766(5) B = 111.95(3)", V = 3162.7A3, Z = 8, D, = 2.16g cm-:! R = 3.51%, and R, = 3.26%. Both clusters consist of square pyramidal cores of FezCoSez and FezCoSSe, respectively, and in each case the Co atom occupies the apical site of the square pyramid.
A:
A,
Introduction The use of single-atom ligands derived from the main groups of the periodic table for the synthesis of cluster compounds has met with considerable success.2 Of the group 16 elements, the sulfido ligand has been the most extensively used.3 In recent years, however the use of Se and Te in cluster synthesis has led to the isolation of several new cluster^.^ A convenient starting material for the synthesis of chalcogen-bridged clusters is the class of compounds Fez(C0)6@-&),where E = S, Se, or Te.5 A characteristic feature of these compounds is the presence of a reactive E-E bond across which addition of organic and inorganic moieties occur readily. Also, base-induced reductions generate anionic species to which electrophiles can add.6 In both types of reactions, Abstract published in Advance ACS Abstracts, March 1, 1995. (1)(a) Chemistry Department. (b) Regional Sophisticated Instrumentation Center. (2)(a)Whitmire, K. H. J. Coord. Chem. 1988,17,95.(b) Compton, N. A.; Errington, R. J.; Norman, N. C. Adu. Organomet. Chem. 1990, 31, 91. (c) Roof, L. C.; Kolis, J. W. Chem. Reu. 1993,93, 1037. (d) Wachter, J. Angew. Chem., Int. Ed. Engl. 1989,28,1613. (e) Muller, A. Polyhedron 1986,5,323.(0 Wachter, J. J. Cwrd. Chem. 1988,15, 219. (g) Ansari, M.A.; Ibers, J. A. Coord. Chem. Rev. 1990,100,223. (h) Tatsumi, K.; Kawaguchi, H.; Tani, K. Angew. Chem., Int. Ed. Engl. 1993,32,591. (3)(a) Adams, R. D. Polyhedron 1986,4,2003. (b) Adams, R. D.; Babin, J. E.; Mathur, P.; Natarajan, IC;Wang, J. W. Inorg. Chem. 1989, 28,1440. (c) Adams, R. D.; Babin, J. E.; Wang, J.-G.; Wu, W. Inorg. Chem. 1989,28,703.(d) Adams, R. D.; Wang, J.-G. Polyhedron 1989, 8, 1437. (e) Adams, R. D.; Babin, J. E.; Estrada, J. W.; Wang, J.-G.; Hall, M. B.; Low, A. A. Polyhedron 1989, 8, 1885. (0 Mathur, P.; Mavunkal, I. J.; Rugmini, V. J. Organomet. Chem. 1989,367, 243. Shaowu, D.; Nianyong, Z.; Pengcheng, C.; Xintao, W.; Jaixi, L. J. Chem. Soc., Dalton Trans. 1992,339. @
0276-733319512314-2115$09.00/0
the chalcogen atoms serve to bridge the Fez(C0)6 unit with the adding moiety. We have previously reported the synthesis of the mixed-chalcogenide compounds Fe2(CO)s@-SeTe)and Fez(CO)s(p-STe)and their reactions with coordinatively unsaturated metal carbonyl species to yield new mixed-metal, mixed-chalcogenide ~ l u s t e r s .Here, ~ we report on the synthesis of Fez(C0)6@-SSe),its reaction with CpCo(CO)a,and characterization of the two products isolated.
Experimental Section General Procedures. Reactions and manipulations were carried out under a n inert atmosphere of nitrogen by means of standard Schlenk techniques. Solvents were deoxygenated was prepared as deimmediately prior t o use. C~CO(CO)Z scribed in the literature.8 Infrared spectra were recorded on a Nicolet Impact 400 FT infrared spectrometer in NaCl cells of 0.1 mm path length as hexane solutions. NMR (lH, 13C, and %e) spectra were obtained on a Varian XI,-300 NMR spectrometer in CDC13 solutions using appropriate references NMR spectra were referenced to an external at 25 "C. The (4)(a)Flomer, W. A.; ONeal, S. C.; Kolis, J. W.; Jeter, D.; Cordes, A. W. Inorg. Chem. 1988,27,969. (b) O'Neal, S. C.; Pennington, W. T.; Kolis, J. W. Can. J. Chem. 1989, 67, 1980. (c) O'Neal, S. C.; Pennington, W. T.; Kolis, J. W. Inorg. Chem. 1990,29,3134.(d) Roof, L. C.; Pennington, W. T.; Kolis, J. W. J. Am. Chem. Soc. 1990,112, 8172. (e) Kolis, J. W. Coord. Chem. Rev. 1990,105,195. (0 Roof, L. C.; Pennington, W. T.; Kolis, J. W. Angew . Chem., Int. Ed. Engl. 1992, 31,913. (g) Huang, S.-P.; Kanatzidis, M. G. Inorg. Chem. 1993,32, 821. (h) Linford, L.;Raubenheimer, H. G. Adu. Organomet. Chem. 1991,32,1. (i) Mathur, P.; Chakrabarty, D.; Mavunkal, I. J. J.Cluster Sci. 1993,4,351. (i) Mathur, P.; Thimmappa, B. H. S.;Rheingold, A. L. Inorg. Chem. 1990,29, 4658. (k) Mathur, P.; Mavunkal, I. J.; Rugmini, V.; Mahon, M. F. Inorg. Chem. 1990,29,4838. (5)(a) Mathur, P.; Mavunkal, I. J.;Rheingold, A. L. J. Chem. SOC., Chem. Commun. 1989,382.(b) Mathur, P.; Mavunkal, I. J.; Rugmini, V. Inorg. Chem. 1989,28,3616.(c) Day, V.W.; Lesch, D. A.; Rauchfuss, T. B. J.Am. Chem. SOC.1982,104,1290.(d) Bogan, L. E.; Rauchfuss, T. B.; Rheingold, A. L. J.A m . Chem. Soc. 1986,107,3843. (e) Lesch, D. A.; Rauchfuss, T. B. Inorg. Chem. 1983,22,1854.(0 Bogan, L. E., Jr.; Lesch, D. A.; Rauchfuss, T. B. J. Organomet. Chem. 1983,250, 429. (6)(a)Seyferth, D.; Henderson, R. S.;Gallagher, M. K. J. Organomet. Chem. 1980,193,C75. (b) Seyferth, D.; Henderson, R. S.; Song, L.-C. J. Organomet. Chem. 1980,192,C1. (c) Seyferth, D.; Henderson, R. S.;Song, L.-C. Organometallics 1982, 1, 125. (d) Seyferth, D.; Womack, G. B.; Henderson, R. S.; Cowie, M.; Hames, B. W. Organometallics 1986,5, 1568. (e) Seyferth, D.; Womack, G. B. Organometallics 1986,5,2360. (0 Seyferth, D.; Womack, G. B.; Song, L.-C. Organometallics 1983, 2, 776. (g) Seyferth, D.; Womack, G. B.; Gallagher, M. K.; Cowie, M.; Hames, B. W.; Fackler, J. P., Jr.; Mazany, A. M. Organometallics 1987,6,283.(h) Seyferth, D.; Kiwan, A. M. J. Organomet. Chem. 1985,286,219.(i) Seyferth, D.; Henderson, R. S.; Song, L.-C. J. Organomet. Chem. 1985,292,9. (7)(a) Mathur, P.;Chakrabarty, D.; Hossain, Md. M. J. Organomet. Chem. 1991,401,167. (b) Chakrabarty, D.; Hossain, Md. M.; Kumar, R. K.; Mathur, P. J. Organomet. Chem. 1991,410, 143. (c) Mathur, P.; Chakrabarty, D.; Hossain, Md. M. J. Organomet. Chem. 1991,418, 415. (d) Mathur, P.; Chakrabarty, D.; Hossain, Md. M.; Rashid, R. S. J., Organomet. Chem. 1991,420,79. (8)Rausch, M. D.; Genetti, R. A. J. Org. Chem. 1970,35,3888.
0 1995 American Chemical Society
Notes
2116 Organometallics, Vol. 14,No. 4,1995
standard of MezSe (6 = O), and the spectra were obtained at the operating frequency of 57.23 MHz; 90" pulses were used with 1.0 s delay and 1.0 s acquisition time. Preparation of Fez(CO)&-sSe). A solution of NazSOs (1 g, 7.94 mmol) and NazSeO3 (1.5 g, 8.67 mmol) in 35 mL of HzO was added to a flask containing an ice-cooled solution prepared from 5 mL (17.11 mmol) of Fe(C0)5, 12 mL of 50% aqueous KOH, and 40 mL of CH30H. After being stirred for 0.5 h, the reaction mixture was cooled to 0 "C and acidified with 6 M HC1. The resulting black precipitate was filtered off in air, washed with distilled water, and dried in vacuo. The solid was then extracted with four 25 mL portions of CHzC12, and the combined extracts were filtered and evaporated to dryness. The solid residue containing the mixture of Fes(C0)g@a-S)@s-Se),FedC0)901s-S)2,and FedC0)9@3-Se)z(1.8g) was added to a solution of NaOMe (9 g of Na in 400 mL MeOH), and the mixture was stirred at room temperature until complete dissolution had taken place. The solution was diluted with hexane (150 mL) and water (100 mL) and acidified with 6 M HC1. After separation of the layers, the aqueous phase was further extracted with hexane and the combined organic extracts were washed with H2O and drieyl over anhydrous Na2S04. The organic fraction was concentrgted and subjected to chromatography on a silica column. sing hexane as eluant, in order of elution, the following compounds were obtained: Fez(C0)6@??)(12%); FeZ(CO)&-SSe) (15%) [IR (v(CO),cm-') 2081 (m), 2040 (vs), 2004 (vs)]; Fez(C0)6@-Sez) (13%). Preparation of C ~ C O F ~ Z @ ~ - S ~ )(1) Z (and C OCpCoFez)~ @s-S)@s-Se)(CO)6(2). A hexane solution (75 mL) of Fez(C0)6(0.6 mL) was (u-SSe) (0.25 g, 0.64 mmol) and C~CO(CO)Z stirred at room temperature under N2 for 10 h. The solvent was removed in vacuo, and the residue was chromatographed on a silica gel column using hexane as eluent. In order of elution the following compounds were isolated: dark red 1 [yield 0.09 g (25%);IR (v(CO),cm-') 2060 (m), 2036 (vs), 2030 (sh), 1994 (s), 1983 (vs), 1955 (w), 1947 (w); 'H NMR 5.85 ppm (5, C5H5);I3C NMR 207.4 ( 8 , CO), 82.4 ppm (s, C5H5); "Se NMR 796.4 ppm (s); mp 143-145 "C. Anal. Calcd for 1: C, 23.5; H, 0.89. Found: C, 23.6; H, 1.171; dark red 2 [yield 0.11 g (34%);IR (v(CO), cm-I) 2063 (m), 2039 (vs), 2032 (sh), 1997 (s), 1986 (vs), 1957 (w),1951 (w); 'H NMR 5.84 ppm (9, C5H5); I3C NMR 206.6 (6, CO), 83.4 ppm (9, C5H5); 77SeNMR 737.8 ppm (5); mp 148-150 "C. Anal. Calcd for 2: C, 25.7; H, 0.09. Found: C, 26.1; H, 1.171. Crystal Structure Determination of CpCoFez@s-Se)z(CO)e (1). Black crystals of 1 were grown from a hexane/ dichloromethane solution by slow evaporation of solvent at -5 "C. A crystal of approximate dimensions 0.3 x 0.3 x 0.15 mm3 was selected for the X-ray diffraction study. Crystallographic data are summarized in Table 1. The data were measured at room temperature on a CAD4 automatic four-circle diffractometer in the range 2" s 0 s 24";5460 reflections were collected of which 2888 were unique with I 2 2dn. Data were corrected for Lorentz and polarization effects, a linear crystal decay of 11.8%(based on the standard reflection intensities) during data collection, and a b s ~ r p t i o n .The ~ structure was solved by direct methods and refined using the SHEIX'O suite of programs. In the final least squares cycles all atoms were allowed t o vibrate anisotropically. Hydrogen atoms were included at calculated positions. Final residuals after 12 cycles of blocked-matrix least squares refinement were R = 0.0385 and R, = 0.0312, for a weighting scheme of w = 2.7018/[u2(F) 0.000190(F)2]. The maximum final shift/esd was 0.001. The maximum and minimum residual densities were 0.47 and -0.43 e A-3, respectively. Final fractional atomic coordinates
r
+
(9)Walker, N.; Stewart, D. Acta Crystallogr., Sect. A 1983,39,158. (10)(a) Sheldrick, G. M. SHELX86, a computer program for crystal structure determination, University of Qttingen, 1986. (b) Sheldrick, G. M. SHELX76, a computer program for crystal structure determination, University of Cambridge, 1976.
Table 1. Crystallographic Data for 1 and 2 compound 2
1
formula fW
cryst syst space group a, A
b, A c, A
a, deg
Z
D(calc), g p(Mo Ka), cm-l
no. of reflns collcd no. of obsd reflns weighting scheme final F indices, % he,,,, Aemin, e A-3 max, min abs cons
CiiHsCoFezSez06 561.7 triclinic P1 6.638( 1) 14.675(4) 17.844(7) 111.37(3) 100.80(2) 89.88(2) 1585.9 4 2.35 72.5 1064 48 298 5460 2888 w = 2.7018/[a2(F) 0.OOO 190(F)2] R = 3.85, R, = 3.12 0.47, -0.43 0.863, 0.600
+
CI1H5coFe~SSe06 514.8 monoclinic c2/c
34.994( 10) 6.599(2) 14.766(5) 111.95(3) 3162.7 8 2.16 52.7 1984 48 298 2776 1626 w = 2.7640//[u2(F) 0.000498(F)2] R = 3.51, R, = 3.26 0.27, -0.28 0.371, 0.914
+
Table 2. Selected Bond Distances and Angles for CpCoFez@~-Se)z(CO)6 (1) Fe( 1)-Se( 1) Fe( 1)-Se(2) Fe(2)-Se( 1) Fe(2)-Se(2) Se(2)-Se( 1) Fe(1)-Co(1)-Se(1) Fe(l)-Co(l)-Se(2) Fe(2)-Co(l)-Se(l) Fe(2)-Co(l)-Se(2) Fe(l)-Se(l)-Se(2) Fe(l)-Se(2)-Se(l) Fe(2)-Se(2)-Se(l) Fe(2)-Se(l)-Fe(l) Fe(2)-Se(2)-Fe(l) Fe(2)-Co( 1)-Fe( 1) Se(2)-Fe(l)-Se(l)
(a) Bond Distances (A) 2.364(3) Co( 1)-Fe( 1) 2.359(3) Co(1)-Fe( 2) 2.364(3) Co(1)-Se( 1) 2.365(3) Co( 1)-Se(2) 3.106(4) (b) Bond Angles (deg) 58.0(0) Co(l)-Fe(l)-Se~l) 57.8(0) Co(1)-Fe(1)-Se(2) 58.2(0) Co(l)-Fe(2)-Se(2) 58.2(0) Co(1)-Se(1)-Fe(1) 48.8(0) Co(1)-Se(1)-Fe(2) 49.0(0) Co(l)-Se(2)-Fe(l) 48.9(0) Co(l)-Se(2)-Fe(2) 97.2(0) Co(l)-Se(l)-Se(2) 97.3(0) Co(l)-Se(Z)-Se(l) 87.8(2) Se(2)-Co( 1)-Se( 1) 82.2(0) Se(2)-Fe(2)-Se(l)
2.565(5) 2.551(4) 2.284(4) 2.29 l(3)
55.0(0) 55.3(0) 55.4(0) 67.0(2) 66.5(0) 66.9(0) 66.4(0) 47.3(0) 47.2(0) 85.5(2) 82.1(0)
and isotropic thermal parameters are given in the supplementary material; bond distances and bond angles are given in Table 2. Crystal Structure Determination of CpCoFe&s-S)@sSe)(CO)s (2). Black crystals of 2 were grown from a hexane/ dichloromethane solution by slow evaporation of solvent at -5 "C. A crystal of approximate dimensions 0.15 x 0.15 x 0.2 mm3 was selected for the X-ray diffraction study. Crystallographic data are summarized in Table 1. The data were measured at room temperature on a CAD4 automatic fourcircle diffractometer in the range 2" s 0 s 24";2776 reflections were collected of which 1626 were unique with I 2 2 d n . Data were corrected for Lorentz and polarization and also absorpt i ~ n The . ~ structure was solved by direct methods and refined using the SHELX'O suite of programs. Early convergence revealed that the Se(1) and S(1) positions were disordered in the ratio of 67:33 with their primed analogues. This disorder is not depicted in the ORTEP plot, where only the position of the unprimed atoms is illustrated. The very proximate disordered moieties are indicated by bracketed labels. In the final least squares cycles all atoms except for the partial occupiers Se(1') and S(1') were allowed t o vibrate anisotropically. Hydrogen atoms were included at calculated positions. Final residuals after 10 cycles of least squares were R = 0.0351 and R, = 0.0326, for a weighting scheme of w = 2.7640/[u2(F) + 0.000498(F)21.The maximum final shift/esd was 0.001. The
Notes
Organometallics, Vol. 14,No. 4,1995 2117
Table 3. Selected Bond Distances and Angles for C P C O F ~ Z ~ ~ J - S ) ~ ~(2)~ - S ~ ) ( C ~ ) ~ (a) Bond Distances (A) 2.538(4) Se(1)-Fe( 1) 2.521(4) Se( 1)-Fe(2) 2.29 l(7) S(1)-Fe(1) 2.298( 16) S( 1)-Fe(2)
Fe( 1)-Co( 1) Fe(2)-Co( 1) Se(1)-Co( 1) S( 1)-Co( 1) Fe(2)-Co(l)-Fe(l) Fe(2)-S(l)-Fe(l) Fe(2)-Se(l)-Fe(l) S(l)-Fe(l)-Se(l) S(l)-Fe(2)-Se(l)
(b) Bond Angles (deg) 86.7(4) S(1)-Co(1)-Fe(1) 97.0(6) S(1)-Co( 1)-Fe(2) 95.8(3) S(l)-Co( 1)-Se(1) 83.2(4) Se(1)-Co(1)-Fe(1) 83.1(4) Se(l)-Co(l)-Fe(2)
Scheme 1. Formation of 1 and 2
2.345(7) 2.334(7) 2.3 11(11) 2.326( 13)
RT, 10 h
co oc"c0
Hexane
56.8(3) 57.5(4) 84.7(4) 57.8(2) 57.8(2)
maximum and minimum residual densities were 0.27 and -0.28 eA-3, respectively. Final fractional atomic coordinates and isotropic thermal parameters are given in the supplementary material; bond distances and bond angles are given in Table 3.
2
1
frequencies observed for 2. lH and 13C NMR spectra confirm the presence of Cp ligands in 1 and 2. The 77Se NMR spectra of 1 and 2 showed a single peak in each Synthesis of Fez(CO)s(p-SSe).The mixed-chalcocase. Comparison with the 77Se NMR spectra of genide Fez(CO)&SSe) was obtained by a method Fes(CO)g@s-Se)zand Fe3(CO)g@3-S)@3-Se)shows the similar to that used for the preparation of Fez(CO)&replacement of a Fe(C013 group by a CpCo group shifts Se2).11J2 An aqueous solution of a mixture of NazS03 the signal downfield by 18 and 59 ppm, re~pective1y.l~ and NazSeO3 was added to a methanol solution containMolecular Structures of 1 and 2. ORTEP drawing Fe(C0)5 and KOH. After room-temperature stirring ings of compounds l and 2 are shown in Figures l and and workup, Fez(CO)6@-SSe)was separated by column 2, respectively. Both molecules exhibit a heavy atom chromatography from the other products formed in the square pyramidal geometry with the Co atom occupying reaction, Fez(C0)6@-Sz)and Fez(cO)s(p-Sez). An optithe apical site. Overall, the core structure is similar to mum yield of 15%of Fez(CO)6@-SSe)was obtained when that of (q5-C5Me5)Co@3-S)zFeZ(C0)6.13The average Coa 8:9 molar ratio of NazS03 and NazSeO3 was used. Like Fe bond distances in 1 (2.558 A) and 2 (2.529 are Fez(CO)6@-Tez),Fez(CO)&-SSe) decomposes rapidly in similar to the average Co-Fe distance of 2.539 A in (q5the solid form, but in solution it can be stored at 0 "C CsMe5)Co@3-S)zFez(CO)6 but are shorter than the averfor several days. The IR spectrum of Fez(C0)6@-SSe) age Co-Fe bond distances reported for FeCoz(C0)9@3shows carbonyl stretching frequencies which are almost Se) (2.581 All5 and other Fe-Co mixed-metal clusters the exact mean of the corresponding frequencies obFezCo (C0)11@4-S)2(2.58 FezCoz(C0)11@4-PPh)z and Fez(CO)&served in the spectra of Fez(CO)6(pu-Sz) -G~~BU)~~ (2.62 and H ( C ~ ) M O C ~ F ~ ( C O ) ~ @ ~(2.684 Sed. A). In 1, the two Co-Se bond distances are almost Synthesis and Characterization of CpCoFez(p3identical (Co-Se(1) = 2.284(4) and Co-Se(2) = Se)z(CO)s (1) and CpCOFez(ps-S)(ps-Se)(CO)a(2). 2.291(4)A) which indicates that the Co atom lies on the When a hexane solution containing Fez(CO)6@-SSe)and perpendicular bisector of the Fe(lI-Fe(2) segment. CpCo(C0)zwas stirred for 10 h, after chromatographic Although in 2 the Co atom is bonded to different workup, two products were obtained and characterized chalcogen atoms, the almost equal bond distances of as CpCoFe&3-Se)z(CO)6 (1)and CpCoFe~@3-S)@3-Se)- Co-S (2.298(16) A) and Co-Se (2.291(7) indicate (CO)6 (2) (Scheme 1). Formation of 1 from an Fez(C0)6that, in 2 also, the disposition of the Co atom in the @-Sez)impurity is unlikely on account of the following. square pyramidal core is as symmetric as in compound FT-IR spectroscopy confirmed that Fez(CO)6@-SSe)did 1. The average Fe-Se bond distance in 1 (2.363 A) is not contain any Fez(CO),j(p-Sez)impurity. In solution, longer than the average Fe-Se bond distance in 2 (2.323 Fez(CO)6@-SSe)converts very slowly to Fez(CO)&-Sez) A) but comparable to the average Fe-Se bond distances (after 24 h, there is less than 5% conversion), and this in Fe3(CO)g@3-Se)218(2.35 A) and in FedC0)9@3-S)@3would not account for formation of 1 in 25% yield. Sell9 (2.351 A). It is shorter than the average Fe-Se Compound 1 has previously been prepared in 56% yield bond distance of 2.437 A reported for Fes(CO)g@s-Se)from the room-temperature reaction of Fez(CO)s(p-Sez) @3-Te).19 The Fe-Co-Fe angles in both 1 and 2 are and CpCo(C0)zin THF solvent and has been spectrosimilar (87.8(2)and 86.7(4)", respectively). scopically characterized.ll The related compound (q5Assuming that the S and Se atoms act as 4-electron C5Me5)Co(p3-S)zFez(co)6has been similarly obtained donors, both 1 and 2 are 50-electron clusters, and the and structurally characterized by X-ray analysis.l3 The formal application of the 18-electron rule would predict infrared spectra of 1and 2 display identical CO stretchtwo metal-metal bonds as observed. According to the ing pattern, with the stretching frequencies observed for 1 being 2-4 cm-' lower than the corresponding (14)Unpublished results for W e NMR data: Fes(CO)&s-Se)z, 6
Results and Discussion
A)
A
(11)Seyferth, D.; Henderson, R. S. J . Organomet. Chem. 1981,204, 333. (12)Mathur, P.; Chakrabarty, D.; Hossain, Md. M.; Rashid, R. S.; Rugmini, V.; Rheingold, A. L. Inorg. Chem. 1992, 31, 1106. (13)Cowie, M.; DeKock, R. L.; Wagenmaker, T. R.; Seyferth, D.; Henderson, R. S.;Gallagher, M. K. Organometallics 1989, 8, 119.
778.5;F ~ ~ ( C O ) B ( U & ~ ) ( U6~ 6-7S'9~.)7. , (15)Strouse, C. E.;Dahl, L. F. J . Am. Chem. Soc. 1971, 93, 6032. (16)Vahrenkamp, H.; Wucherer, E. J. Angew - Chem., Int. E d . Engl. 1981,20, 680. (17)Gusbeth, P.;Vahremkamp, H. Chem. Ber. 1985,118, 1770. (18)Dahl. L. F.: Sutton. P. W. Inorrr. Chem. 196s. 2. 1067. (19)Gervasio, G.J . Organomet. Chim. 1993, 445; 147
Notes
2118 Organometallics, Vol. 14, No. 4, 1995
C18
04
09
2
6
7
Figure 1. Molecular structure of 1 with the atom-labeling scheme. c9
06
Figure 2. Molecular structure of 2 with the atom-labeling scheme. PSEP theory, the presence of 7 skeletal electron pairs Supplementary Material Available: Tables of complete in each cluster correctly predicts the nido octahedral bond lengths and angles, nonbonded distances, fractional structure. atomic coordinates, and isotropic and anisotropic thermal parameters (23pages). Ordering information is given on any Acknowledgment. We thank the Department of current masthead page. Science & Technology, Government of India, for support of this work. OM9408775
