0 Copyright 1995
Volume 14, Number 6,June 1995
Amencan Chemical Society
Communications (q6-Polyarene)Mn(CO)3+ Complexes as Manganese Tricarbonyl Transfer Reagents. A Convenient and General Synthetic Route to (Arene)Mn(CO)3+Complexes Shouheng Sun, Lee K. Yeung, and Dwight A. Sweigart" Department of Chemistry, Brown University, Providence, Rhode Island 02912
Tae-Young Lee, Su Seong Lee, and Young K. Chung* Department of Chemistry, Seoul National University, Seoul 151-742, Korea
Susan R. Switzer and Robert D. Pike* Department of Chemistry, College of William and Mary, Williamsburg, Virginia 23187 Received March 22, 1995@ Summary: (Polyarene)Mn(C0)3+ complexes containing naphthalene-type ligands can be readily synthesized in high yield. These complexes function as efficient manganese tricarbonyl transfer (MTT) reagents by rapidly and cleanly transferring the Mn(CO)3+ moiety to other arenes upon warming in dichloromethane. The activation of arenes by coordination to transition metals provides a useful synthetic route to functionalized arenes and cyclohexadienes. The manganesemediated functionalization of arenes is particularly attractive in this regard because the relevant complexes, (arene)Mn(CO)s+, are known to undergo high-yield regio- and stereoselective attack by a very wide range of nuc1eophiles.l The resultant cyclohexadienyl com~~
@Abstractpublished in Advance ACS Abstracts, May 1, 1995. (1)(a)Pauson, P. L.; Segal, J. A. J. Chem. Soc., Dalton Trans. 1976, 1677, 1683. (b) &ne-Maguire, L. A. P.; Honig, E. D.; Sweigart, D. A. Chem. Rev. 1984,84,525. ( c ) Chung, Y. K.; Williard, P. G.; Sweigart, D. A. Organometallics 1982,I , 1053. (d) Pike, R. D.; Sweigart, D. A. Synlett 1990,563. (e) Krow, G. R.; Miles, W. H.; Smiley, P. M.; Lester, W. S.; Kim, Y. J. J. Org. Chem. 1992,57, 4040. (0 Pearson, A. J.; Shin, H. Tetrahedron 1992,48,7527. (g) Chung, T.-M.; Chung, Y. K. Organometallics 1992, 11, 2822. (h) Lee, S.; Chung, Y. K.; Yoon, T.S.; Shin, W. Organometallics 1993,12,2873. (i) Woo, K.; Carpenter, G. B.; Sweigart, D. A. Inorg. Chim. Acta 1994,220,297.
plexes readily liberate the functionalized arene upon oxidative removal of the metal, as shown in eq 1. Alternatively, cyclohexadienes can be generated by reactivation of the cyclohexadienylcomplexes with NO+, followed by a second nucleophilic addition.1d!2
B Three synthetic methods have been reported for the coordination of arenes t o the Mn(C0)3+ moiety: (1) heating Mn(C0)sBr and the arene in the presence of AICl3, (2) treating a CHzClz solution of Mn(C0)sBr with ~~
(2) (a) Chung, Y. K.; Sweigart, D. A.; Connelly, N. G.; Sheridan, J. B. J. Am. Chem. Soc. 1986,107, 2388. (b) Pike, R. D.; Ryan, W. J.; Carpenter, G. B.; Sweigart, D. A. J.A m . Chem. Soc. 1989,lI I, 8535. (c) Miles, W. H.; Brinkman, H. R. Tetrahedron Lett. 1992,33,589. (d) Lee, T.-Y.; Kang, Y. K.; Chung, Y. K.; Pike, R. D.; Sweigart, D. A. Inorg. Chim. Acta 1993,214,125.
0276-733319512314-2613$09.00/0 0 1995 American Chemical Society
2614 Organometallics, Vol. 14, No. 6, 1995 a Ag(1) salt and then adding the arene and warming, and (3) heating Mnz(C0)lo and the arene in trifluoroacetic anhydride (TFAA) and strong acide3 A rather large number of monocyclic arenes have been coordinated by these methods. However, attempts to coordinate polycyclic arenes such as naphthalene produced at best a trace of the desired complex, along with varying amounts of partially hydrogenated p r ~ d u c t . For ~~~ example, attempted synthesis of (naphtha1ene)Mn(C0)3+ by method 1 gave instead (tetralin)Mn(C0)3+. Herein we report that method 2 is, in fact, capable of giving good yields with polycyclic arenes, provided all reagents are thoroughly dried and contact with donor solvents is avoided (vide infra). Thus, compounds 1-6 were readily prepared in good yield and found t o be stable in the solid state.5 They were also found t o provide an excellent vehicle for polyarene functionalization by nucleophilic addition to the coordinated ring; these reactions as well as the chemistry of the monoanions of 1-5, obtained by two-electron reduction, will be reported in a future communication. The naphthalenetype ligands in 1-6 as well as the $-heterocyclic ligands in 7-93>6were observed to undergo ready displacement by donor solvents. Equation 2 shows the reaction with
+
(polyarene)Mn(CO)g
+
3 MeCN
+
(MeCN)sMn(CO)3
+
:&, 10
(2)
acetonitrile; some half-lives in CHzClz containing 1.0 M MeCN are given in Table 1. It can be seen that the naphthalene-type complexes in particular are extremely reactive. It is possible to compare this reactivity to that previously reported' for the analogous reaction of (toluene)Mn(C0)3+ (10) with MeCN. In sharp contrast t o the behavior of the polyarene complexes 1-9, the toluene complex is calculated t o have a half-life of ca. 4 (3) Jackson, J. D.; Villa, S. J.; Bacon, D. S.; Pike, R. D. Organometallics 1994, 13, 3972 and references therein. (4) Stobart, S. R.; Zaworotko, M. J. J . Chem. Soc., Chem. Commun. 1984, 1700. (5) For the synthesis of 1-9, it is important that all glassware, solvents, and chemicals be carefully dried. Complexes 1-7 were made typically as follows: Mn(C0)sBr (1.0 g) and AgBF4 (1.1equiv) were dissolved in 50 mL of CHzCl2 and refluxed for 1 h under Nz in the dark. The polyarene (2-4 equiv) in 10 mL of CHzClz was then added and the reaction mixture refluxed overnight. After it was cooled to room temperature, the solution was filtered through Celite and concentrated to ca. 20 mL in uucuo and the product precipitated with diethyl ether. The yellow [(arene)Mn(CO)31BF4salts were washed repeatedly with ether and dried in uacuo. Complex 9 was synthesized by the TFAA method, as previously described for 8.3 The new polyarene complexes were thoroughly characterized by IR (YCO 2073 + 7,.2017 k 5 cm-') and 'H NMR, which showed the absence of any free polyarene. The coordination of the metal to a terminal ring in 1 was confirmed by X-ray crystal1ography.ll 'H NMR (CDzClz): 1 , 6 8.76 (d, J = 9 Hz, H5), 8.25 (d, J = 9, HE), 8.18-7.96 (m, H637s9J0),7.72 (d, J = 9, H4), 7.29 (d, J = 6, H1), 6.80 (m, H2s3);2,6 8.06 (s, H 5 9 , 7.507.35 (m, H1s4),6.80-6.65 (m, H2s3);3,6 8.11-7.41 (m, H 4 9 6.76 (m, H3), 6.55 (d, J = 5 Hz, H2),2.97 (s, Me); 4, 6 8.25-8.10 (m, H5-9, 6.22 (s, H'43), 2.95 (s, Me1,4);5, 6 7.81 (d, J = 9 Hz,H5), 7.44 (d, J = 9, H6), 7.37-7.26 (m, H4f9, 7.08 (s, HI), 6.02 (d, J = 6, H3), 4.15 ( 6 , OMe2), 4.04 (s, OMe7); 6,6 8.07 (m, H6), 7.90-7.75 (m, H5,?, 7.17 (d, J = 7 Hz, H4), 6.75 (m, H3), 6.58 (d, J = 6, HZ), 3.90-3.60 (m, H9J0);9, d (in CD3COCD3)8.53 (2, J = 7.8 Hz, Ha), 8.17 (d, J = 6.6, HI), 7.93 (m, H53), 7.70 (t, J = 6.9, H7), 7.68 (d, J = 7.0, H4), 7.09 (t, J = 6.6, H3), 6.66 (t, J = 6.4, H2). Complexes 7 and 8 have been previously reported.316 Satisfactory elemental analysis was obtained for the new complexes 1-6 and 9. (6) Lee, S. S.;Chung, Y. K.; Lee, S. W. J . Organomet. Chem., submitted for publication. (7) Kane-Maguire, L. A. P.; Sweigart, D. A. Inorg. Chem. 1979, 18, 700.
&
,@@
2
6
Mn(CO)3+
Mn(C0)3+
Mn(C0)3+
1
3
2 9
5
4
~
1
0
6
@ OJQ OJQ:
Mn(CO)3+
Mn(C0)3+
Mn(C0)3+
I
8
9
Figure 1. Manganese complexes investigated (the counterion was BF4- in all cases). Table 1. Yield and Reactivity Data for Complexes 1-9
%yield 69 half-life for 50 eq 2, minb polyarene
Communications
86 -1
9W
89" 77 16
87 2.2
87 55
89 250
76 260
Product consists of a mixture with the metal coordinated to either the methylated or unsubstituted ring (ratio 1 : l for 3 and 4:l for 4). At 25 "C in dichloromethane containing 1.0 M MeCN.
*
-
years! This reactivity difference most likely is due to easier v6 q4 ring slippage for 1-9, which accompanies associative attack by MeCN a t the metal. A similar interpretation has been presented to explain the rate of arene displacement by P-donor nucleophiles from (arene)Cr(CO)s complexes, which also follows the reactivity order arene = naphthalene > phenanthrene > > > benzene.8 The important reactivity factor is the change q4 ring in resonance energy (ARE) upon the q6 slippage. ARE follows the order benzene (84 kJ) > phenanthrene (59 kJ) > naphthalene (44kJh8 With the rough assumption that changes in ARE alone determine the relative reactivity of 1,2, and 10, the half-life order is predicted to be 10 > 1 > 2 (20 000:1:0.0025). This approximates the data in Table 1 (400OO:l:-0.02). The ease with which complexes 1-9 undergo arene displacement by donor solvents suggested to us that they may be effective at transferring the Mn(C0)3+ moiety to other arenes; i.e., they may function as manganese tricarbonyl transfer (MTT) reagents? Indeed, it was found that simply heating complexes 1-9 in dichloromethane containing a modest excess of any of a number of arenes led to clean substitution, as illustrated by eq 3 for complex 6. The time of heating and reaction yields are given in Table 2.1° Not surprisingly, the ease of manganese tricarbonyl transfer from 1-9 to an arene correlates with the rate of reaction with MeCN (Table 1). Thus, MTT from 8 and 9 generally required more than 10 h (at 70 "C), while 2 reacted within 1 h (at 40 "C). With respect t o yield and time of
-
(8)Zhang, S.;Shen, J. K.; Basolo, F.; Ju, T. D.; Lang, R. F.; Kiss, G.; Hoff, C. D. Organometallics 1994, 13, 3692. (9) In analogy, (naphthalene)Cr(CO)3and (N-methylpyrrole)Cr(CO)s are known to function as chromium tricarbonyl transfer reagents.I2,l3
Communications
Organometallics, Vol. 14, No. 6, 1995 2615
Table 2. Percent Yields for Manganese Tricarbonyl Transfer from Complexes 1-9 to Various Arenes in Analogy to eq 30 1
arene
3
2
5
4
7
6
8
9
60 (17) 88 ( l O Y
80 (10) 90 (8) 57 (10Y 47 (16)
44(6)
56 (21)* 71 (20) 69 (17)
42 (17)* 66 (18) 73 (17)
77 (17) 86 (15)
66 (18)
75 (10) 62 (10) 31 69(3)
(lor
91 (1) 94 (1) 70 (10) 98 (lOY
a The reaction times (h) are given in parentheses. All yields refer to isolated products. Unless noted otherwise, the reaction temperature was 70 "C for complexes 1, 4-6, 8, and 9 and 40 "C for 2, 3, and 7. The number of equivalents of free arene used in the exchange reactions was as follows for each complex: 1,4-6 (1.5 equiv); 2 , 3 (2 equiv); 8 , 9 (5 equiv); 7 (10 equiv). Reaction conditions were 70 "C and 1.5 equiv of free arene. Five equivalents of free arene used.
@
Mn(C0)3+
+
arene
n
(arene)Mn(CO)3+
+
@@
(3)
reaction, any of the naphthalene-type complexes are excellent transfer reagents. However, when the cost of the precursor polyarene and the ease of complexation to Mn(C0)3+ are considered, the a-methylnaphthalene and acenaphthene complexes (3 and 6) are perhaps the preferred MTT reagents. The important point to note is that the synthesis of (arene)Mn(C0)3+complexes via Ml" reagents constitutes an exceptionally mild procedure and can be utilized to coordinate arenes that fail (10) The arene exchange reactions, as in eq 3,were performed as follows: under N2, the complex (1-9 0.2 g) was dissolved in ca. 25 mL of CHzClz and the arene added in modest excess (Table 2). At this stage the reaction solution was either refluxed (40 "C) or sealed in a pressure bottle and heated to 70 "C for the times indicated in Table 2. In order to determine appropriate reaction times, initial synthetic runs were followed by IR. The product and reactant have similar IR spectra in the vco region, but the differences are sufficient so that the reactant is easily distinguished as a shoulder (or separate peak) on the product IR bands. After IR spectra showed no trace of the starting complex 1-9, the reaction mixture was cooled, concentrated, and filtered through Celite (if necessary). Diethyl ether was used to precipitate the product, which was washed with ether and dried in uacuo. 'H NMR (and IR) indicated that the products were very pure. Satisfactory elemental analyses were obtained for all previously unreported [(arene)Mn(CO)slBFdcomplexes obtained by this procedure.
to react satisfactorily by the other available methods (vide supra) due to the presence of sensitive functional groups or other reasons. In summary, we have shown that (po1yarene)Mn(CO)s+ complexes can be synthesized in good yield and that they are effective general reagents for the transfer of the Mn(C0)3+ moiety to arenes. Indeed, it is even possible to transfer Mn(C0)3+ to naphthalene-type complexes to obtain naphthalenes with a manganese carbonyl unit attached to each ring on the same side.l' Acknowledgment. This work was supported by grants from the National Science Foundation (CHE9400800 and INT-93127091, the Korea Science and Engineering Foundation (No. 93-0500-02-01-3and the Korean-USA Cooperative Science Program), the Thomas F. and Kate Miller Jeffress Memorial Trust, and the donors of the Petroleum Research Fund, administered by the American Chemical Society (PRF No. 26521GB1). Supplementary Material Available: Text a n d a table giving characterization d a t a for the compounds prepared i n t h i s paper (4 pages). Ordering information is given on a n y current masthead page. OM950213A ~
~
~~
~
~~
~~
(11)Sun,8.; Dullaghan, C. A.; Carpenter, G. B.; Sweigart, D. A. To be submitted for publication. (12) Kiindig, E. P.; Perret, C.; Spichiger, S.; Bernardinelli, G. J. Orgunomet. Chem. 1986,286, 183. (13)Goti, A.;Semmelhack, M. F. J. Orgunomet. Chem. 1994, 470, c4.
