J. Am. Chem. SOC.1992, 114, 4594-4601
4594
The Synthesis and Structure of (p-q2,q3-Pentadienyl)(p-alkanethiolato)pentacarbonyldiiron (Fe-Fe) Complexes. An Unusual Bonding Mode for the Pentadienyl Group Dietmar Seyferth,* Lea L. Anderson, Fernando Villafafie, and William M. Davis Contribution from the Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139. Received November 7, 1991
Abstract: The reaction of 5-bromopenta-l,3-diene with [Et3NH][(p-Co)(p-Rs)Fe2(Co)6](R = t-Bu, Et, Ph) complexes gave products of type (p-q2,q3-CH2=CHCHCHCH2)(p-RS)Fe2(C0)5 as well as the respective (p-RS)2Fe~(C0)6.Similar reactions with l-bromohexa-2,4-diene resulted in formation of (p-q2,q3-CH2=CHCHCHCHCH3)(p-RS)Fe2(C0)5, which suggests that the reaction of the [(p-CO)(p-RS)Fe2(CO)6]- anions with the halides is an SN2' process. The structure of (p-q2,q3-CH2=CHCHCHCH2)(p-PhS)Fe2(CO)5 has been determined by X-ray diffraction. This compound crystallizes in the triclinicspacegroupPT (no.2) with a = 9.763 (6) A, b = 11.132 (4) A, c = 9.346 (4) A, a = 111.71 (3)O, j3 = 111.57 (4)O, y = 92.03 (5)O, V = 860.2 (8) A, and Z = 2. Refinement has converged at R = 0.035 and R, = 0.040 on the basis of 217 parameters varied and 1799 unique observations.
Introduction The pentadienyl ligand is known to coordinate to transition metal atoms in a number of ways. The most common pentadienyl complexes are those in which this ligand is bonded to the metal in an q5 or q 3 fashion. Examples of neutral complexes in which the former type of bonding is operative include compounds 1,l 2a: and 2b.3 Compounds 3: 4,5 5,5and 66 are examples of the q3 bonding mode. One compound which provides an example of
the rare q 1 bonding mode, 7, undergoes isomerization upon UV irradiation to q5 and q3 complexes (eq I).' Compounds 1 and
a I
en&
ex0
2 are representatives of a large class of q5-pentadienyl complexes in which the ligand has the "U" geometry. The "S"geometry also is possible, and 88and g9 are examples. The pentadienyl group
I
Cl- Mo(C0)2
PhzPf
\
WPPh2
2
c; A"
a
R ~ = H .R ~ = H R'=H, R2-Me
I CC-Mo, R'
~1
r__._.
H
4
8
J7 *.-.
Br-Mo(CO)2 Ph2P 'PPh2 \
AA I Fe(PMe3)2 I
/
U
I
.a:
>,/
=MC,R~ = H
W-PEI3
-
- -..- -...
$A
R2
P
also may be q1 bonded to the metal atom via the central carbon atom, as in 1O.Io More exotic types of bonding are known. The
\
4 IQ
(1) Ernst, R. D. Chem. Rev. 1988, 88, 1255 (a useful review on q5-open pentadienyl compounds). (2) Seyferth, D.; Goldman, E. W.; Pornet, J. J. Organomet. Chem. 1981, 208, 189. ( 3 ) Paz-Sandoval, M.A.; Powell, P. J. Organomet. Chem. 1981,219,81. (4) Paz-Sandoval, M.A.; Powell, P.; Drew, M.G. B.; Perutz, R.N. Organometallics 1984, 3, 1026. ( 5 ) Lee, G.-H.; Peng, S.-M.; Liu, F.-C.; Mu,D.; Liu, R . 4 . Organometallics 1989, 8, 402. ( 6 ) Bleeke, J . R.; Hays, M.K. Organometallics 1984, 3, 506.
reaction of a,*-allylheptacarbonyldiiron (Fe-Fe) with simple acetylenes gives products in which the substituted pentadienyl (7) Lush, S.-F.; Liu, R.-S.Organometallics 1986, 5 , 1908. (8) Lee, T.-W.; Liu, R . 4 . Organometallics 1988, 7, 878.
(9) Stahl, L.; Hutchinson, J. P.; Wilson, D. R.;Emst, R.D. J . Am. Chem. Soc. 1985, 107, 5016. (10) Bleeke, J. R.; Earl, P. L. Organometallics 1989, 8, 2735.
0002-7863 I921 15 14-4594%03.00/0 0 1992 American Chemical Societv
(p-~2,~3-CH~(CH)3CHr)(p-RsJFe2(CO)5 ( R = t-Bu, Et, Ph)
J. Am. Chem. Soc., Vol. 114, No. 12, 1992 4595
ligand is bonded to the iron atoms in q l , q2, and v3 fashion, 11 (eq 2)." A related bonding mode of a 1,s-dimethylpentadienyl ligand was found in the cluster complexes (F-1 ,5-Me2C5H5)(p-
o,?r-allyl complexes.18a W e wrote these (incorrectly) as 15;the correct description is that shown as 18a,b.In view of this finding, it was of interest to establish how the pentadienyl ligand, intro-
R
H
ll
R=H.Me
H ) ( F ~ - S ) R U S ( C Oand ) ~ ~(P-1 ,~-M~~CSH,)(~-H)(~~-~)RU~(C~)IS in which the organic ligand was bonded to two adjacent Ru atoms in an q2,q3manner, 12.12 A hexacarbonyldiiron complex has been 188
m
duced by reaction of the [(p~-Co)(p-Rs)Fe,(Co)~]anions with 5-bromo-l,3-pentadiene, would be bonded to the Fe2(CO)6unit. In any case, the pentadienyl ligand would have to be a threeelectron donor, and one likely possibility seemed to be 19.
Ru-RU
reportedI3 in which the pentadienyl ligand is bonded as shown in 13: the central carbon atom is a bridging carbene carbon, while the other four carbon atoms are olefinic and $-bonded to the two E2
Results end Discussion
12
iron atoms. The pentadienyl ligand also may be. of the q l , type, ~ ~ as in 1414and of the $,q4 type, as in 15.Is Related to 11 in that
II 14 the pentadienyl is a t the same time V I , v2,and v3 bonded to metal atoms is complex 16 (eq 3).16 Finally, among these exotica, there is complex 17."
* Ni
Ni
&+++ 12
During the last eight years we have been investigating the rich chemistry of the [(p-CO)(p-RS)Fez(CO)6]- anions.'* In earlier studies we found that they reacted with allyl chloride to give (1 1) Sumner, C. E. Jr.; Collier, J. A,; Pettit, R. Organometallics 1982, 1 , 1350. (12) Adams, R. D.; Babin, J. E.; Tasi, M.; Wolfe, T. A. J . Am. Chem. Soc. 1988, 110, 7093. (13) Navarre, D.; Pariier, A,; Rudler, H.; Daran, J. C. J . Organomet. Chem. 1987. 322. 103. (14) Melendez, E.; Arif, A. M.; Rheingold, A. L.; Ernst, R. D. J . Am. Chem. Soc. 1988, 110, 8703. (15) Lehmann, R. E.; Bockman, T. M.; Kochi, J. K. J . Am. Chem. SOC.
-1990 - - -, -112 .-, 458 . - -. (16) Deeming, A. J.; Arce, A. J.; De Sanctis, Y. D.; Bates, P. A.; Hursthouse, M. B. J . Chem. SOC.,Dalton Trans. 1987, 2935. (17) (a) Rienicker, R.; Yoshiura, H. Angew. Chem., Znt. Ed. Engl. 1969, 8, 677. (b) Kriiger, C. Angew. Chem., Znr. Ed. Engl. 1969, 8, 678. (18) (a) Seyferth, D.; Womack, G. B.; Archer, C. M.; Dewan, J. C. Organometallics 1989,8,430. (b) Seyferth, D.; Womack, G. B.; Archer, C. M.; Fackler, J. P. Jr.; Marler, D. 0. Organomerallics 1989, 8, 443.
The reaction of the triethylammonium salts of the [(p-C0)(p-RS)Fe,(cO),]- anions ( R = t-Bu, Et, Ph) (prepared by addition of triethylamine to Fe3(C0)12and the respective thiol in THF a t room temperaturelga) with 5-bromopenta-l,3-dkne, CH2=CHCH=CHCH2Br, occurred during 1-1.5 h a t room temperature. A color change from dark brown-red to red v w noted, and a white solid ([Et3NH]Br) precipitated. In each reaction two products were formed: the pentadienyl product, (p-~2,~3-CH~=CHCHCHCHz)(~-RS)F~(C0)5, 2h ( R = t-Ru), b ( R = Et), and c ( R = Ph), and the respective (p-RS)zFe2(C0)6 complex, 21/22 (Table I). The latter is an often encountered byproduct of reactions of the [(p-CO)(p-RS)Fe2(C0)6]- anions and usually is formed as a mixture of the a,e and e,e isomers (21 and 22, respectively). In the present reactions such isomer mixtures also were formed, and the yield of 21/22 was greater than usually observed.
21,a.e
22,e,e
Elemental analysis and mass spectrometry established that a product of type (CSH7)(p-RS)Fe2(CO)shad been formed. The fact that the product had a n Fe2(CO)5 framework (rather than the usual Fe2(CO),) indicated that the pentadienyl ligand was functioning as a five-electron donor, Le., that both C-C bonds were involved in bonding to the two iron atoms. An unambiguous structure determination was provided by a single crystal X-ray diffraction study of 2Oc ( R = Ph). An ORTEP p!ot of the molecule is shown in Figure 1, an inspection of which shows the pentadienyl group to be bonded to the Fe2(CO)S unit by v2 (a-olefinic) and q3 (a-allyl) type bonding (as in compounds of type 12), Le., the ligand is solely a-bonded to the Fe2(CO)Sunit. Hence in the complexes 20 we have another example of an unusual mode of bonding of the pentadienyl group. In contrast to the formation of the ruthenium cluster complexes that contain a p-q2,q3-pentadienyl ligand, the present synthesis is straightforward and proceeds in high yield. It should be more generally applicable to the preparation of pentadienyl-metal complexes. A closer inspection of Figure 1 and the bond distances is of interest. C(7) and C(8) are the olefinic carbon atoms which ere coordinated to Fe(2) in an qz manner. The remaining carbon atoms of the CSH7ligand comprise the allylic moiety which is
4596 J. Am. Chem. SOC.,Vol. 114, No. 12, 1992
Seyferth et al.
H
Table I. Yields of (u-RS),Fe,(CO)A,21/22 and
(~-v~,v~-CH~=CHCHCH~H~)(~-RS)F~~(CO)~, 20 R 21 1 2 7 (%) t-Bu 43 Et 51 Ph 60 'Based on S. bBased on Fe. C8
206 (%) 53 48 31 Figure 2. Line drawing of (p-q2,q3-CH2=CHCHCHCH2)(p-RS)Fe2(CO),, 20.
c7
3
Cll
Table 11. Relevant 'H and "C NMR Spectral Data for
(p-$,$-CH,=CHCHCHCH,)(p-EtS)Fe,(CO),, 2Ob
d (ppm)
~~~
I
I
W
c5
' J (Hz) 2J (Hz) assignment 'H NMR Spectral Data (in CDCI, Solution) 0.34 dd 13.04 2.78 syn-CH2CHCHCH=CH2 0.78 dd 10.54 2.09 syn-CH2CHCHCH=CH2 0.95 dt 13.01 7.60 CH2CHCHCHeCH2 1.92 d 6.95 anti-CH2CHCHCH=CH2 2.22 dd 7.34 2.40 anti-CH2CHCHCH=CH2 3.30 dd 7.68 5.02 CH2CHCHCH=CH2 5.96 m CH?CHCHCH=CH, 8 (ppm) JCH (Hz) assignment "C NMR Spectral Data (in CDCI, Solution) 27.45 t 156.6 CHZCHCHCH=CH, 37.25 t 160.4 CH2CHCHCH=CH2 54.33 d 159.1 CH2CHCHCH=CH2 63.84 d 168.6 CH2CHCHCH=CH2 89.27 d 166.8 CH2CHCHCH=CH2 ~~
Figure 1. ORTEP plot of (p-q2,$-CH2=CHCHCHCH2)(p-PhS)Fe2(CO),, 20. Important bond distances (A) and angles are as follows: Fe(1)-Fe(2). 2.780 (2); Fe(l)C(9), 2.088 (6); Fe(l)C(lO), 2.046 (6); sets of resonances, each integrating for one proton, which corFe(1)-C(l l), 2.128 (7); Fe(2)-C(7), 2.132 (6); Fe(2)-C(8), 2.281 (6); responds to the seven protons of the pentadienyl ligand. The two C(7)C(8), 1.371 (8); C(8)2.00(I)), 2.85 (3.61). ([(BME-DACO)Ni],Ni)Br,: 7.144 (2), 10.931 (2), 17.296 (3) A; 91.72 (2)O, P2,/c, 4, 4.O0/SO.O0, 2053 (I > 2.0a(I)), 4.46 (4.84). The pseudo-square-planar NiN2S2complex 2 has cis sulfur donor atoms and a tetrahedral twist of 18.4'. The Ni-SSulfinato distance of 2.140 ( I ) A is significantly shorter than the Ni-Sthiolatedistance, 2.163 (1) A. The trimetallic 4 contains a staircaselike structure where two molecules of 1 serve as metallothiolate ligands to the central Ni2+ creating an NiS4 square plane (dihedral angle between best square planes = 103.4O).
Introduction The synthetically vexing air sensitivity of anionic transitionmetal thiolate complexes generally reflects ill-understood chemical reactions which, if controlled, might prove useful in the preparation of organic disulfides, sulfoxides, and sulfinic acids. In addition, such reactions are of import to loss of activity of both industrial and enzymatic catalysts which contain sulfided metal centers. The slow reaction of solutions of the complex [N,N'-bis(mercapt0-
ethyl)-1 ,S-diazacyclooctane]nickel(II), (BME-DACO)Ni" (l),' with O2provided opportunity to isolate and characterize products that result from both electron transfer and oxygenation a t sulfur, eq 1. This paper reports those results as well as an isotopic labeling ( 1 ) (a) Mills, D. K.; Reibenspies, J. H.; Darensbourg, M. Y. Inorg. Chem. 1990, 29, 4364. (b) Mills, D. K.; Hsiao, Y.M.; Farmer, P. J.; Atnip, E. V.; Reibenspies, J. H.; Darensbourg, M. Y. J. Am. Chem. SOC.1991, 113, 1421.
0002-7863192115 14-4601%03.00/0 0 1992 American Chemical Society
