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organometallics 1990, 9, 1113-1119
Synthesis, Characterization, and Reaction Chemistry of a Family of 1- Iridacyclohexa-2,4-diene Complexes' John R. Bleeke,' Wei-Jun Peng, Yun-Feng Xie, and Michael Y. Chiang Department of Chemistry, Washington University, St. Louis, Missouri 63 130 Received August 29, 1989
The reaction of (C1)Ir(PEt3), with potassium 2,4-dimethylpentadienide produces the l-iridacyclo, (1) via an iridium-centered activation hexa-2,4-diene complex (IrCH=C(Me)CH=C(Me)CH,)(PEt,),(H) of a pentadienyl C-H bond. The kinetic product of this reaction is the fuc isomer (la),which slowly isomerizes to the thermodynamically preferred mer isomer (lb). Treatment of l b with methyl trifluoromethanesulfonate results in hydride abstraction and production of [ (IrCH=C(Me)CH=C(Me)CH2)(PEtJ3]+O3SCF 3 u ( 4 Mo Kol linear abs coeff, cm-' abs cor applied data:param ratio R"
R,b
Refinement Summary 6107 4027 43.661 $ scans/empirical 14.5 0.050
0.067
" R = CllFol- I~cII/CI~oI. bRw= = 1/U2(Fo).
[D(lF0I- l~c1)2/C4~0121"2; w
K a radiation. Three standard reflections were measured every 100 events as check reflections for crystal deterioration and/or misalignment. Data reduction and refinement were done by using the Enraf-Nonius SDPVAX structure determination package (modified by B. A. Frenz and Associates, Inc., College Station, TX) on a VAX 11/780 computer. Crystal data and details of data collection and structure analysis are summarized in Table III." The iridium atom position in 8 was calculated from a Patterson map; the remaining non-hydrogen atoms were found by successive full-matrix least-squares refinement and difference Fourier map calculations. Non-hydrogen atoms in the cation were refined anisotropically, while those in the anion exhibited relatively large thermal parameters and were refined isotropically. Hydrogen atoms were placed at idealized positions with use of the program HYDRO and included in the structure factor calculations but not refined.
Summary A new s y n t h e t i c a p p r o a c h to 1-metallacyclohexa-2,4diene complexes has been developed. This method utilizes p e n t a d i e n i d e as the source of the ring carbon a t o m s and involves a metal-centered C-H b o n d activation step. In the prototypical reaction, (IrCH=C(Me)CH=C(Me)CH,)(PEt,),(H) (1) is p r o d u c e d in high yield f r o m the rea c t i o n of ( C l ) I r ( P E t 3 ) 3 w i t h p o t a s s i u m 2,4-dimethylpentadienide. The hydride ligand i n 1 is readily removed u p o n treatm e n t w i t h m e t h y l trifluoromethanesulfonate, producing t
I
(2). In (IrCH=C( Me)CH=C (Me)CH,) (PEt3),+03SCF3.. . L
solution at 25 "C, 2 is u n s t a b l e with respect t o decomposition t o [(~5-1,3-Me2cp)Ir(PEt3)2(H)]+03SCF3(3). T h i s ~~~~
(15) Atomic scattering factors were obtained from: International Tables for X - R a y Crystallography; Kynoch Birmingham, England, 1974; Vol. IV.
Organometallics 1990, 9, 1119-1123 process may involve an a-hydride elimination step. Compound 2 reacts with a series of 2e ligands (L) at low temperature to produce a family of adducts having the
. (IrCH=C(Me)CH=C(Me)CH,)1 I
formula [ (PEt3l3L1+O,SCF,- (L = I-, CO, NCMe, and CNCMe,; compounds 4-7, respectively). Reaction of 2 with PMe, also leads to adduct formation but is accompanied by phosphine ex, change. The product in this case is [(IrCH=C(Me)I
CH=C(Me)CHz)(PEt3)(PMe,)3]+03SCFf (8). Treatment of 2 with lithium diisopropylamide (LDA) in acetone results in proton abstraction and production of the stable metallabenzene complex (Ir=CH=C(Me)=CH=C(Me)=CH) (PEt,), (9). The chemistry of metallacyclohexadienes and metallabenzenes continues to be investigated in our laboratories 1
I
1119
and will be described in future reports.
Acknowledgment. Support from the National Science Foundation (Grant CHE-8520680) and a loan of IrCl3-3Hz0 from Johnson Matthey, Inc., are gratefully acknowledged. Washington University’s X-Ray Crystallography Facility was funded by the National Science Foundation’s Chemical Instrumentation Program (Grant CHE-8811456). Washington University’s High Resolution NMR Service Facility was funded in part by National Institutes of Health Biomedical Research Support Instrument Grant 1 S10 RR02004 and by a gift from Monsanto Co. Supplementary Material Available: Listings of final atomic coordinates,thermal parameters, bond lengths, and bond angles for compound 8 (7 pages); a listing of observed and calculated structure factor amplitudes (16 pages). Ordering information is given on any current masthead page.
Thermal and Photolytic Substitution of Dimanganese Decacarbony1 with Trif luorophosphine Casey C. Grimm, Paul E. Brotman, and Ronald J. Clark” Department of Chemistry, The Florida State University, Tallahassee, Florida 32306 Received August 29, 7989
Under thermal conditions, the PF3 substitution of Mnz(CO)loproduces five different compounds: 1Mnz(CO)g(PF3),1,1’-Mnz(CO)&PF3)2, 1,2-Mnz(C0)8(PF3)2,1,1’,2-Mn2(C0)7(PF3)3, and 1,1’,2,2’-Mn2(CO),(PF3),. Photolytic excitation results in the formation of four additional compounds. Substitution is rigorously limited to the replacement of four carbon monoxides, but that replacement is fairly readily achieved. Compounds are identified by using a combination of GC-MS, 19FNMR, and IR. Back reaction of 1,1’,2,2’-Mnz(C0)6(PF3)4 with 13C0produces only the previously observed PF,-substituted compounds having extensive label. Side products produced include the monometallic hydride series HMn(CO),,(PF,), (x = 1-5), the hydrogen-bridgedseries Mnz(p-H)(p-PFz)(CO),(PF,), (x = 2-5), and the bisphosphido-bridged series Mnz(p-PFz)z(CO),~,(PF,),( x = 2-7).
Introduction With monometallic carbonyl complexes such as MO(CO)~ and Fe(C0)5, PF, can sequentially replace CO and ultimately yield the compounds Mo(PF3), and Fe(PF3),.’r2 Trifluorophosphine has been shown to form cr and T bonds to metals with bonding characteristics similar to those of CO., Numerous PF, analogues of mononuclear metal carbonyls have been prepared, and their intermediate species have been extensively ~ t u d i e d . ~However, little is known about the substitution reactions of PF, with simple polynuclear complexes such as Mnz(CO)lo5Fe2(CO)g, and C O ~ ( C O ) ~The . substitution chemistry of dimanganese decacarbonyl has been studied under both thermal and photolytic conditions by using various ligands.&1° With bulkier ligands, substitution stops with the replacement of two carbonyls, while with smaller ligands up to four ligands may be replaced. The mechanism of substitution was controversial for many years. It is now generally assumed that under thermal conditions, the substitution occurs through the dissociative loss of a CO to form an unsaturated enneacarbonyl complex with the metal-metal bond intact.” Under photolytic conditions, dissociative loss of a CO is observed, as well as a second mechanism involving the homolytic cleavage of the met-
* To whom correspondence should
be sent.
al/metal b ~ n d . ~ JThe ~ J relative ~ rates of the two mechanisms have been shown to be wavelength dependent with the ratio of the homolytic cleavage route to the dissociative CO loss increasing with increasing wavelengths. The clear separation of a potentially large number of physically similar compounds and their definitive characterization are among the problems that stand in the way of an extensive study of PF, substitution into polynuclear (1)Clark, R.J.; Hoberman, P. I. Inorg. Chem. 1965,4 , 1771. (2)Clark, R.J. Inorg. Chem. 1964,3, 1395. (3)Kruck, T. Angeco. Chem., Int. Ed. Engl. 1967,6,53.Nixon, J. F. Adv. Inorg. Chem. Radiochem. 1985,29,41. (4) Clark, R. J.; Busch, M. A. Acc. Chem. Res. 1973,6 , 246. (5)Clark, R.J.;Hargaden, J. P.; Haas, H.; Sheline, R. K. Inorg. Chem. 1968, 7,673. (6)Treichel, P.M. Comprehensive Organometallic Chemistry; Wilkinson, G.; Stone, F. G. A.; Abel, E. W., Eds.; Pergamon: Oxford, 1982; Vol 4, Chapter 1, p 9,and references therein. (7) Herrick, R. S.; Brown, T. L. Inorg. Chem. 1984,23,4550.Jackson, R. A,; Poe, A. Inorg. Chem. 1979, 18, 3331. (8)Harris, G.W.; Coville, N. J.; Organometallics 1984,4, 908. (9)Herrick, R.S.Rev. Inorg. Chem. 1986,8, 1. Seder, T.; Ouderkirk, A.; Church, S.;Weitz, E. ACS Symp. Ser. 1987,333,81,and references ~~
within.
(10)Hepp, A. F.;Wrighton, M. S. J. Am. Chem. SOC.1983,105, 5934. (11)Coville, N. J.;Stolzenberg, A. M.; Mutterties, E. L. J.Am. Chem. SOC.1983,105, 2499. (12)Kobayashi, T.;Ohtani, H.; Noda, H.; Teratani, S.; Yamazaki, H.; Yasufuku, H. Organometallics 1986,5, 110. (13)Kobayashi, T.; Yasufuku, K.; Iwai, J.; Yesaka, H.; Noda, H.; Ohtani, H. Coord. Chem. Rev. 1985,64, 1.
0276-7333/90/2309-ll19$02.50/0 0 1990 American Chemical Society
