Syntheses, Fluxional Behavior and Crystal Structures of the endo and exo η^3-Allyl Monocarbonyl Dithiocarbonate and Dithiocarbamate Molybdenum Complexes: Crystal Structures of exo-[Mo(η^3-allyl)(η^2-S2COC2H5)(CO)(η^2-dppm)] and endo-[Mo(η^3-allyl)(η^2-S2C

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Com mu ni ca tion

Syn the ses, Flux ion al Be hav ior and Crys tal Struc tures of the endo and exo

3

_{-Allyl Monocarbonyl Dithiocarbonate and Dithiocarbamate Mo lyb de num}

Com plexes: Crys tal Struc tures of

exo-[Mo(

3

-allyl)(

2

-S2COC2H5)(CO)(

2

-dppm)] and

endo-[Mo(

3

-allyl)(

2

-S2CNC4H8)(CO)(

2

-dppe)]

Kuang-Hway Yiha* ( ), Gene-Hsiang Leeb ( ) and Yu Wangc ( ) a_{De part ment of Ap plied Cos me tol ogy, Hung Kuang In sti tute of Tech nol ogy,}

Shalu, Taichung, Tai wan 433, R.O.C.

b_{In stru men ta tion Cen ter, Col lege of Sci ence, Na tional Tai wan Uni ver sity, Tai pei, Tai wan, R.O.C.} c_{De part ment of Chem is try, Na tional Tai wan Uni ver sity, Tai pei, Tai wan 106, R.O.C.}

The novel endo and exo com plexes [Mo( 3-C3H5)( 2-L2)(CO)( 2-dppm)] are ac ces si ble by the re ac tions of the com plexes [Mo( 3-C3H5)(CO)2( 2-L2)(X)] (L2, X = S2COEt, CH3CN; S2CNC4H8; S2CNEt2) with dppm. X-ray crys tal struc tures of exo-2 and endo-5 have been em ployed to elu ci date the two ori en ta tions.

Fluxionality in the com plexes [Mo( 3- allyl)(CO)2(L1)- (L2)X]1 (L1,L2: pyrazolylborate, diketonate, dithio, X: neu -tral monodentate ligand; L1,L2: diphos, pyridylphosphane, X: ha lide) is at trib uted to an intramolecular trigonal twist, in which the ro ta tion of the tri an gu lar face formed by the L1L2X groups is rel a tive to the face formed by the allyl and the two car bonyl groups. A novel piv oted dou ble switch2 and a pyridyl -exchange mech a nism have been re ported when the L1L2 lig ands were re placed by pyridylphosphane or their ox ide lig -ands. X-ray crys tal lo graphic stud ies of the above-mentioned com plexes have so far re vealed three dif fer ent solid-state struc tures as de picted in Fig. 1 (A-C).

The rigid and nonrigid cyclopentadienyl com plexes endo-, exo-cis-syn-[CpMo(NO)(CO){ 3

-CH(Ph)CHCH2}] [BF4]3 and endo, exo-[( 5-C5H4-COPhe-OMe)Mo( 3- allyl) (CO)2]4 have be come known re cently. On the other hand, con for ma tions and flux ion al be hav ior of com plexes in clud -ing Mo( 3-C3H5)( 2-SS)(CO) moi ety have not been very

well stud ied.

Treat ment of [Mo(CH3CN)( 3-C3H5)(CO)2( 2- S2COEt)] (1a) with dppm in acetonitrile at room tem per a ture yields mix tures of the air-stable and or ange-yellow com plexes [Mo( 3-C3H5)( 2-S2COEt)(CO)( 2-dppm)] (endo, exo-2) with ca. 88% yield (Scheme I). In the endo and exo ori en ta tions, the open faces of the allyl group point to ward the car bonyl group and away from it, re spec tively. The spec tro -scopic5 and an a lyt i cal data of endo, exo-2 are ob tained. In the FAB mass spec tra, base peaks with the typ i cal Mo iso tope dis tri bu tion are in good agree ment with the [M]+ mo lec u lar masses of endo, exo-2. The IR spec tra of endo, exo-2 shows one ter mi nal car bonyl-stretching band at 1801 cm-1. In the 1H NMR spec trum of exo-2 the meth y lene pro tons of the dppm ligand and allyl pro tons ex hibit res o nances at 2.41, 3.86 and at 2.24, 2.55 (Hanti), 3.78, 4.21 (Hsyn), 4.92 (Hcen ter), re -spec tively. The cor re spond ing 13C{1H} NMR sig nals are at 41.5, and 54.5, 58.4, and 68.9. The 31P{1H} spec tra of Jour nal of the Chi nese Chem i cal So ci ety, 2002, 49, 479-482 479

* Cor re sponding au thor. Tel: +886-4-26318652 ext. 5308; Fax: +886-4-26321046; E-mail: khyih@sun rise.hkc.edu.tw

L X C Mo O C L O X L C Mo O C L O C L X Mo L C O O A B C

Fig. 1. Three pos si ble struc tures A, B and C for [Mo( 3_-C 3H5)(CO)2(L1)(L2)X]. N C C Ph2P PPh2 C Ph2P PPh2 C Mo i O O O Mo O Mo + 1a endo-2 (1:5) exo-2 S S EtOC S S EtOC S S EtOC C C H3

Scheme I Re agents and con di tions: i, dppm, CH3CN, r.t., 5 min, 88%

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endo-, exo-2 show res o nances at 6.9, 32.8 (2_J

P-P = 52.7) and 3.4, 27.4 (2JP-P = 63.1) with a 1:5 ra tio.

Sim i lar endo-3,4 and exo-3,4 com plexes are pre pared by us ing the 16 elec tron com plexes 1b,c with dppm in refluxing acetonitrile (Scheme II). Ra tios of 1:4 and 1:9 of com plexes endo, exo3 and endo, exo4 are ob tained by in te -grat ing from 31_P{1_{H} NMR spec tra. To in ves ti gate the re la} -tion be tween ori en ta -tions and diphos ligand, we car ried out the re ac tions of 1b-c with dppe yield ing com plexes [Mo( 3 C3H5)( 2-L2)(CO)( 2-dppe)]5 (L2 = S2CNC4H8, endo, exo-5; L2 = S2CNEt2, endo, exo6) with ra tios of 6:1 and 5:1, re spec tively (Scheme II). On the ba sis of the abovementioned ex -per i ments, we can con clude: (1) the dppm ligand im proves the for ma tion of exoprod ucts, whereas the dppe ligand im -proves endo-prod ucts, and (2) exo-com plexes show larger JP-P cou pling con stants than the endo-com plexes.

The afore men tioned con for ma tions of exo-2 and

endo-5 have been per formed by X-ray dif frac tion stud ies at 1endo-50 K.6 ORTEP plots of exo-2 and endo-5 are shown in Figs. 2 and 3, re spec tively. Clearly, the open face of the allyl group is to -ward the car bonyl group in endo-5 and away in exo-2. The two struc tures con firm unequivalent allyl groups. One of the sul fur at oms of dithioligand is trans to the diphos: S(1)- P(2), 141.77(4) in exo-2 and S(1)-Mo-P(1), 156.16(2) in endo-5, while the other is trans to car bonyl: S(2)-Mo-C(1), 167.89(10) in exo-2 and S(2)-Mo-C(1), 170.65(6) in endo-5. The Mo-S and Mo-allyl bond dis tances in exo-2 and endo-5 are con sis tent with the val ues re ported for MoII

-S and nu mer ous Mo-allyl sys tems. The dif fer ence be tween the bond dis tances and intercarbon an gle of allyl group in exo-2 (1.371(7), 1.365(7) Å and 121.5(5) ) and endo-5 (1.399(3), 1.423(3) Å and 116.8(2) ) is not very sig nif i cant and is in the re gion of re lated MoII-al lyl ic com pounds (1.31-1.42 Å,

125 ).7

To test the gen er al ity of these re ac tions, we have stud -ied other Mo-allyl sys tems. In ter est ingly, the re ac tions of [Mo( 3-C3H5)( 2-L2)(CO)2(X)] (L2, X = H2BPz2’;

pentane-480 J. Chin. Chem. Soc., Vol. 49, No. 4, 2002 Yih et al.

L C L C Ph2P L PPh2 L C Ph2P L PPh2 L C Ph2P L PPh2 L C Mo C4H8NCS2 -Et2NCS2 -O O i O Mo O Mo + Mo O 1b-c 3 4 34 5 6 (1:4) (1:9) L Ph2P L PPh2 L C Mo O + 5 6 (6:1) (5:1) c: b: L ii endo- exo- endo- exo-Yields(%) 80 85 Yields(%) 82 87

Scheme II Re agents and con di tions: i, dppm, CH3CN, re flux, 1 h; ii, dppe, CH3CN, re flux, 1 h

Fig. 2. ORTEP draw ing for [Mo( 3_{- C} 3H5)( 2

S2COC2H5)(CO)( 2-dppm)] (exo-2). Se lected

bond dis tances (Å) and an gles ( ) are as fol -lows: Mo-C(2) 2.357(4), Mo-C(3) 2.328(4), C(4) 2.341(4), S(1) 2.5157(6), S(2) 2.6102(9), C(2)-C(3) 1.371(7), C(3)- C(4) 1.365(4); S(2)-Mo-C(1) 167.89(10), Mo-P(2) 141.77(4), C(2)-C(3)-C(4) 121.5(5), P(1)-Mo-P(2) 67.44(3), S(1)-Mo- S(2) 68.53(3).

Fig. 3. ORTEP draw ing for [Mo( 3_{- C} 3H5)( 2

S2CNC4H8)(CO)( 2-dppe)] (endo-5). Se lected

bond dis tances (Å) and an gles ( ) are as fol -lows: Mo-C(2) 2.349(2), Mo-C(3) 2.230(2), C(4) 2.305(2), S(1) 2.5588(8), S(2) 2.6248(5), C(2)-C(3) 1.399(3), C(3)-C(4) 1.423(3); S(2)-Mo-C(1) 170.65(6), P(2) 156.160(19), C(2)-C(3)-C(4) 116.8(2), P(1)-Mo-P(2) 78.858(18), S(1)-Mo-S(2) 68.071(17).

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2,4-dionate, CH3CN) with dppm gave Mo(CO)2(dppm)2 by the re place ment of an ionic bidentate lig ands. This may be due to elec tronic fac tors since H2BPz2 and pentane- dionate ligand are weaker do nors than dithiocarbamato and dithiocarbonato lig ands.

In or der to in ves ti gate the fluxionality be tween endo, exo-3 and endo, exo-5 com plexes, the vari able-temperature 1

H and 31P{1H} NMR spec tra were re corded in the range of 210 K-333 K. In the range of 210 K-273 K, none of 1H and 31

P{1H} NMR spec tra changed and the ra tio was re tained. As de picted in Fig. 4, the vari able-temperature 31P{1H} NMR spec tra show interconversion of endo-5 to exo-5 at 318 K and four dou blets of dif fer ent in ten sity at 278 K. The line shapes cal cu lated from vari able-temperature 1H NMR spec tra8 of endo, exo-3 at 318 K yield val ues of 15.6 ± 0.2 kcal mol-1

for G‡_{and 14.8 0.2 kcal mol}-1_for_{endo, exo-5 at 298 K. The} large ac ti va tion en ergy of endo, exo-3 com pared with endo, exo-5 is due to the bite an gles and that dppm in creases the bar rier most ef fec tively. Ad di tion of free dppe and C4H8NCS2 -ligand had no ef fect on these vari able- tem per ature spec tra of endo, exo-3,5 and there fore a re ar range ment in volv ing a - - pro cess or dis so ci a tion of the dppe or dithiocarbamato ligand seems un likely. No tice ably, the orig i nal ra tios of endo and exo were re tained when the vari abletemperature ex per i -ments were fin ished. Compared with other intramolecular trigonal twist re ar range ment com plexes, the ac ti va tion en

-ergy of endo, exo-3,5 is larger than those of com plexes [M( 3- C3H5)(CO)2(diphos)I]10 (M = Mo, W; diphos = dppm, dppe) (10.0-11.9 kcal mol-1), [Mo(CO)( 3- allyl){ 2 S2P(OEt)2}(X)]11 (X = CH3CN, 11.6; C5H10NH, 12.6 kcal mol-1) but sim i lar to the allyl ro ta tion com plex [Mo( 5 C5H4- COPhe-OMe)( 3-allyl)(CO)2] (15.0 kcal mol-1).4 Ro ta -tion of the allyl group has been re ported in com plexes [CpMo( 3-allyl)(CO)2]12 and [Pd( 3-allyl)( 2-LL)]9 but no ex am ple in a Mo( 3-allyl)(CO)( 2-SS) sys tem. The spec tral ob ser va tions on the dy namic spe cies and the data of ac ti va -tion en ergy13 of com plexes endo, exo3,5 re veal that the iso -mers un dergo mu tual ex change by the ro ta tion of the allyl bond. The de ter mi na tion of other con for ma tions of com -plexes with [Mo( 3-allyl)(CO)(L1L1)(L2L2)]+ type (LL: neu -tral bidentate lig ands) and con trol ling the regiochemistry of nucleophilic at tack on the endo, exo-com plexes are cur rently un der in ves ti ga tion.

AC KNOWL EDGE MENT

We thank the Na tional Sci ence Coun cil of Tai wan, the Re pub lic of China and Hung Kuang In sti tute of Tech nol ogy for sup port.

Re ceived May 28, 2002.

Key Words

Flux ion al be hav ior; Struc tures; endo exo 3-allyl stereoisomer; Dithiocarbonate; Dithiocarbamate.

REF ER ENCES

1. (a) Cot ton, F. A.; Frenz, B. A.; Stanislowski, A. G. Inorg.

Chim. Acta 1973, 7, 503. (b) Cot ton, F. A.; Stanislowski, A.

G. J. Am. Chem. Soc. 1974, 96, 5074. (c) Brisdon, B. J.; Grif -fin, G. F. J. Chem. Soc. Dal ton Trans. 1975, 1999. (d) Brisdon, B. J.; Woolf, A. A. J. Chem. Soc. Dal ton Trans. 1978, 291. (e) Brisdon, B. J.; Den nis, E. A.; Kathleen, E. P. J.

Chem. Soc. Dal ton Trans. 1980, 1317.

2. Espinet, P.; Hernando, R.; Iturbe, G.; VillafaeÑ, F.; Orpen, A. G.; Pascual, I. Eur. J. Inorg. Chem. 2000, 1031.

3. Faller, J. W.; Lam bert, C.; Mazzieri, M. R. J. Organomet.

Chem. 1990, 383, 161.

4. van Staveren, D. R.; Weyhemüller, T.; Metzler-Nolte, N.

Organometallics 2000, 19, 3730 and ref er ences cited

therein.

5. Se lected spec tro scopic data: 1H (300 MHz) and 13C{1H} (75

endo and exo 3

-Allyl Mo lyb de num Com plexes J. Chin. Chem. Soc., Vol. 49, No. 4, 2002 481

Fig. 4. Vari able-temperature 31_{P {}1_{H} NMR ob ser va}

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MHz) NMR (CDCl3, rel a tive to SiMe4, mul ti plic ity, as sign

-ment, J in Hz) 31P{1H} (121.5 MHz) NMR (H3PO4 ex ter nal

stan dard). 1a: IR (KBr, CO/cm-1): 1935 (vs), 1860 (vs). 1H

NMR: 1.35 (m, 2H, Hanti), 1.33, (t, 3H, OCH2CH3, JH-H =

11.6), 2.05 (br, 3H, CH3CN), 3.29 (d, 2H, Hsyn, JH-H = 10.8),

4.22 (m, 1H, Hcen tre), 4.46 (q, 2H, OCH2, JH-H = 11.6). 13

C{1H} NMR: 0.9 (s, CH3CN), 13.1 (s, OCH2CH3), 56.4

(br, ter mi nal C of allyl), 67.7 (s, OCH2), 73.2 (br, cen tre C of

allyl), 116.2 (s, CH3CN), 227.2 (s, CO). MS (FAB, NBA,

m/z): 355.9 (M+

). Endo, exo-2: IR (KBr, CO/cm-1): 1801

(vs). MS (FAB, NBA, m/z): 672 (M+), 644 (M+ - CO).

31 P{1H} NMR: endo-2: 6.9, 32.8 (d, 2JP-P = 52.7), exo-2: 3.4, 27.4 (d, 2JP-P = 63.1), 1H NMR: 1.10 (t, 3H, OCH2CH3, JH-H = 11.7), 2.24, 2.55 (d, 2H, Hanti, JH-H = 13.3), 2.41, 3.86 (m, 2H, PCH2), 3.78, 4.21 (m, 2H, Hsyn), 4.00 (m, 2H, OCH2CH3), 4.92 (m, 1H, Hcen tre). 13C{1H} NMR: 13.7 (s, CH3CN), 41.5 (t, PCH2, JP-C = 20.5), 54.5, 58.4 (s, ter mi nal C

of allyl), 66.7 (s, OCH2), 68.9 (s, cen tre C of allyl), 222.6 (s,

CS2), 227.1 (s, CO).

Endo, exo-3: IR (KBr, CO/cm-1): 1781 (vs). MS (FAB,

NBA, m/z): 685 (M+ - CO). 31P{1H} NMR: endo-3: 4.7, 32.4 (d, 2JP-P = 48.1), exo-3: 1.8, 26.9 (d, 2JP-P = 61.6). 13

C{1H} NMR: 204.0 (d, CS2, 3JP-C = 3.5), 227.6, 227.7 (s,

CO). MS (FAB, NBA, m/z): 697 (M+

), 669 (M+ - CO). endo, exo-4: IR (KBr, CO/cm

-1

): 1806 (vs). MS (FAB, NBA, m/z):

671 (M+ - CO). 31P{1H} NMR: endo-4: 4.0, 32.6 (d, 2JP-P =

51.1), exo-4: 0.5, 27.7 (d, 2JP-P = 64.2). endo, exo-5: IR

(KBr, CO/cm-1): 1791 (vs). MS (FAB, NBA, m/z): 711 (M+),

683 (M+ - CO). 31P{1H} NMR: endo-5: 54.5, 82.3 (d, 2JP-P =

26.1), exo-5: 62.9, 86.0 (d, 2JP-P = 39.1). endo, exo-6: IR

(KBr, CO/cm-1): 1791(vs). 31P{1H} NMR: endo-6: 53.3,

82.7 (d, 2JP-P = 26.1), exo-6: 62.3, 86.6 (d, 2JP-P = 39.3).

6. Crys tal data for exo-2: C32H32MoO2P2S2, space group P21, a

= 10.2519(2) Å, b = 12.8528(2) Å, c = 11.7698(2) Å, = 103.0812(9) , V = 1510.61(5) Å3, Z = 2, Dcalcd = 1.474 gcm-3,

= 0.707 mm-l, in de pend ent re flec tions 6668, range =

1.78-27.50 . To tal num ber of pa ram e ters: 353. R = 0.036, Rw

= 0.076; GOF = 1.039, Mo K ra di a tion; = 0.71073 Å; T = 150(1) K; F = 0.946, -0.654e Å3_{. endo}_-5·CH

2Cl2:

C36H39Cl2MoNOP2S2, space group P21/n, a = 11.3200(1) Å,

b = 15.8152(2) Å, c = 19.6732(2) Å, = 90.3932(4) , V = 3521.97(7) Å3_{, Z = 4,}_D

calcd = 1.499 gcm-3, = 0.764 mm-l,

in de pend ent re flec tions 8065, range = 1.65-27.50 . To tal

num ber of pa ram e ters: 407. R = 0.029, Rw = 0.074; GOF =

1.118, Mo K ra di a tion; = 0.71073 Å; T = 150(1) K; F = 0.634, -0.517e Å3. Ab sorp tion cor rec tions of exo-2 and

endo-5 have been car ried out. The two struc tures were solved

by Patterson syn the sis and then re fined via stan dard squares and dif fer ence Fou rier tech niques. Nonhydrogen at -oms were re fined by us ing anisotropic ther mal pa ram e ters. 7. (a) Gra ham, A. J.; Fenn, R. H. J. Organomet. Chem. 1969,

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Stults, B. R. Inorg. Chim. Acta 1977, 7, 503. (g) Brisdon, B. J.; Ewards, D. A.; Paddick, K. E.; Drew, M. G. B. J. Chem.

Soc. Dal ton Trans. 1980, 1317. (h) Faller, J. W.; Chodosh, D.

F.; Katahira, D. J. Organomet. Chem. 1980, 187, 227. (i) Lush, S. F.; Wang, S. H.; Lee, G. H.; Peng, S. M.; Wang, S. L.; Liu, R. S. Organometallics 1990, 9, 1862.

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9. (a) Chowdhury, S. K.; Nandi, M.; Joshi, V. S.; Sarkar, A.

Organometallics 1997, 16, 1806 and ref er ences cited

therein. (b) Kollmar, M.; Goldfuss, B.; Reggelin, M.; Rominger, F.; Helmchen, G. Chem. Eur. J. 2001, 7, 4913. 10. Faller, J. W.; Haitko, D. A.; Ad ams, R. D.; Chodosh, D. F. J.

Am. Chem. Soc. 1979, 101, 865.

11. Yih, K. H.; Lee, G. H.; Wang, Y. J. Organomet. Chem. 1999,

588, 125.

12. (a) King, R. B. Inorg. Chem. 1966, 5, 2242. (b) Davison, A.; Rode, W. C. Inorg. Chem. 1967, 6, 2124.

13. Curtis, M. D.; Eisenstein, O. Organometallics 1984, 3, 887.