Organometallics 1991,10,2743-2751
2743
Reactions of Tertiary Amines with Trinuclear Clusters. 3.+ Reactions of N-Methyipyrrolidine with Ru3(CO),2 and Os3(co)10(CH3CN)2 Michael W. Day, Sharad Hajela, Shariff E. Kabir, Mark Irving, Timothy McPhiilips, Erich Wolf, Kenneth I . Hardcastle, and Edward Rosenberg' Depertment of Chemistry, Callfornia Stare University, Northridge, California 9 1330
Lucian0 Milone, Roberto Gobetto, and Domenico Osella Dipartimento di Chimica Inorpnica, Chimica Fisica e Chimica dei Materlell, Universl di Torino, Via Giuria 7-9, I- 10 125 Torino, Ita& Received November 16, 1990
The reaction of N-methylpyrrolidine with R u ~ ( C O in ) ~the ~ presence of the three reaction promoters
Fe2(CO),(p-SCHzCH3)2(P(C6Hs)3)2 (iron dimer), (CH3I3NO,and (C6H6)&= O-Na+ was studied in the
temperature range 65-80 OC. In the presence of the iron dimer catalyst, in hexane at 68 OC, one major trinuclear product isolated in 15-20% yield proved to be (p-H)2R~3(CO)90C3-~z-CH-N=CCHzCH2CHz) (I). In the presence of trimethylamine N-oxide or sodium benzophenone ketyl in benzene at 80 "C a different I I trinuclear product isolated in 30% yield, OC-H)RU~(CO).&~-~-N=CCH~CH~CH~) (21, is a structural analogue of the major product obtained from the reaction of triethylamine with R u ~ ( C Oin ) ~the ~ presence of the above mentioned diiron reaction promoter. A minor product isolated in the reaction of R U ~ ( C Owith )~~ N-methylpyrrolidine in the presence of (CH3)3N0is the tetranuclear vl-carbene species ( M - H ) ~ R U ~ I (CO)11(~'-C=N(CH3)CHzCH2CHz) (3). Thermolysis of 1 in heptane at 100 "C gave moderate yields of I the compound (p-H)Ru3(CO)~(p3-s3-CH3N-CH=CHCHZCHz) (4),in which two hydrogens have been transferred to the methyne carbon and further rearrangement of the ligand has occurred. The lightly stabilized cluster O S ~ ( C O ) ~ ~ ( C H was ~ C Nreacted )~ with N-methylpyrrolidine in refluxing benzene to give I (p-H)Os3(CO)IO(p-t12-CH3N=CC(H)CH2CH2) (5) and (p-H)Os3(CO)lo(p-~1-CH3N=C(H)CCHzCH2) (6). Compounds 1-5 were characterized by X-ray diffraction methods in the solid state, and 1-6,by 'H NMR and infrared s ectroscopy in solution. Compound 1 crystallizes in the monoclinic space group R l / n , with a = 9.015 (2) b = 16.759 (4)A, c = 13.266 (3)A, and j3 = 95.98 (2)O. Least-squares refinement of 3822 observed reflections gave a final agreement factor of R = 0.048 (R, = 0.055). Compound 2 crystallizes in the monoclinic space group P2,/m, with a = 7.657 (1)A, b = 14.910 (3)A, c = 8.172 (2)A, and 0 = 106.32 (2)O. Least-squares refinement of 1938 observed reflections gave a final agreement factor of R = 0.026 (R, = 0.031). Compound 3 crystallizes in the monoclinic space group P2,/c, with a = 10.198 (1)A, b = 14.229 (2)A,c = 16.512 (3)A, and 0 = 102.34 (1)O.Least-squares refinement of 2033 observed reflections gave a final R = 0.025 (R, = 0.036). Compound 4 crystallizes in the monoclinic space group RJc, with a = 8.858 (2)A, b = 13.455 (5)A, c = 18.400(4)A, and j3 = 118.70 (2)O. Least-squares refinement of 2254 observed reflections gave a final R = 0.043 (R, = 0.045). Compound 5 crystallizes in the orthorhombic space group P212121, with a = 11.567 (2)A, b = 17.653 (6)A, and c = 9.900 (2)A. Leasbsquares refinement of 2600 observed reflections gave a final R = 0.074 (R, = 0.065). I
i
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i
b
i
1,
Introduction In our recent reports of the reactions of tertiary amines with R U ~ ( C Oin) ~the ~ presence of the substitution promoter Fez(CO),(p-SCHzCH3)z(P(C~H~)3)2 we found that products resulting from alkyl cleavage as well as alkyl coupling to the amine are formed (eq l).la We and others formulated the hypothesis that initial carbon-nitrogen bond cleavage proceeds via amine coordination, carbonhydrogen bond activation followed by H-N reductive elimination, and homolytic rupture of the C-N bond to form a carbene-secondary amine ~ o m p l e x . ~The . ~ subsequent formation of alkyl cleavage products could then arise via carbene dissociation, while the coupling products could result via secondary amine dissociation followed by coordination of a second molecule of tertiary amine. In order to test this hypothesis we decided to study the reaction of a cyclic amine with R u ~ ( C O reasoning )~~ that carbon-nitrogen cleavage of an endocyclic C-N bond could 'Parte 1 and 2: See refs 1 and 2.
result in a chelate-stabilized carbeneamine complex. We report here the results of our studies on the reaction of N-methylpyrrolidine with R U ~ ( C O )and ' ~ with Os3(CO)l&CH3CN)2. Although we did not observe a chelatestabilized carbene-amine complex, we did observe the formation of trinuclear complexes with the amine, prior to and after C-N bond cleavage. Even more interesting we observed a marked shift in the product distribution depending on the type of the reaction promoter used (i.e. iron dimer, trimethylamine N-oxide or sodium benzophenone ketyl). Other workers have studied the reactions of cyclic unsaturated amines such as quinolines: phenanthridine: pyrrole,b indolesFband imidazolesk with the lightly stabilized clusters M3(CO),o(CH3CN)2(M = Ru, (1) Aime, S.;Gobetto, R.; Padovan, F.; Botta. M.; Rosenberg, E.; Gellert, R. Organometallics 1987, 6, 2074. (2) Day, M. W.; Hajela, S.;Hardcastle, K.I.; McPhillips, T.; Rosenberg, E.; Botta, M.; Gobetto, R.; Milone, L.; Osella, D.; Gellert, R. W. Organometallics 1990, 9, 913. (3) Laine, R. M. Ann. NY Acad. Sci. 1981, 271. (4) Fish, R. H.; Kim,T. J.; Stewart, J. L.; Busherweller, J. H.; Rosen, R. K.; Dupon, J. W. Organometallics 1986,5,2193 and references therein.
0276-7333/91/2310-2743$02.50/00 1991 American Chemical Society
Day et al.
2744 Organometallics, Vol. 10, No. 8, 1991
alkyl cleavage isomers
H H ,
C,.,NE,t
\
I
\
Figure 1. Solid-state structure of compound 1. All hydrogen positions shown are calculated.
Os); however, only C-H activation of the sp2 carbons was observed. More recently Adams et al. have reported facile
product band from hexane gave analytically pure (p-
H)2R~3(CO)9(p3-a2-CHN=CCH2CH2CH2) ( l ) , whose
structure was subsequently elucidated by single-crystal X-ray diffraction methods and is entirely consistent with the solution 'H NMR data given above. The solid-state structure of 1 is shown in Figure 1, the crystal data are given in Table I, and selected distances and bond angles are given in Table 11. The structure consists of a trimetallic core with two almost e uivalent metal-metal bonds (Ru(l)-Ru(2) = 2.806 (1) and Ru(l)-Ru(3) = Results and Discussion 2.796 (1) A) and one elongated metal-metal bond (Ru(2)-Ru(3) = 3.000 (1)A). The locations of the two hydrides A. Reaction of R U ~ ( C Oand ) ~ ~N-Methylpyrrolidine in the Presence of Fe2(CO)l(r-SCH2CH3)2(P(c6H5)3)2. were calculated by using the potential energy minimum program Hydex.' The location of H(23) as almost in the When N-methylpyrrolidine is refluxed with R u ~ ( C Ofor )~~ plane of the ruthenium triangle is consistent with the long 12 h in hexane in the presence of a catalytic amount of Ru(2)-Ru(3) distance and i h location trans to CO(33) and Fe2(CO)l(p-SCH2CH3)2(P(C6H5)3)2, only one band conCO(22) to fill out the approximately octahedral geometry taining trinuclear ruthenium products is obtained. The around Ru(2) and Ru(3). Similarly, the location of H(13) 'H NMR spectrum in CDC13 of this band showed it to is tucked down below the ruthenium triangle, placing it contain one major product (90% of the total 15-20% obtrans to CO(31) and C0(12), and is Consistent with the tained) with two slightly broadened singlet hydride resoshorter Ru(l)-Ru(3) distance expected for a hydride nances a t -12.16 (1)and -16.44 (1)ppm, a series of three sharing the same edge as another single atom bridge.*V8 multiplets at 2.92 (2, t, Jm = 7.7 Hz), 1.76 (2, t, J H H = 7.7 The organic ligand must donate four electrons to the metal Hz), and 0.96 ppm (2, quintuplet), and a singlet at 5.94 (1) core in order to make 1 a saturated 48e- cluster. The ppm. There were two impurities in the band, as evidenced bridging methyne carbon, C(l), donates two electrons via by the presence of two singlet hydrides a t -14.89 and two fairly symmetric metal-carbon u bonds to Ru(1) and -18.36 ppm, each integrating about 1:20 with one of the Ru(3) (Ru(l)-C(l)= 2.13 (1)A and Ru(3)-C(l) = 2.12 (1) two hydride signals of the major product. The -18.36 ppm A). Two additional electrons are donated by the quatersignal is due to the compound (p-H)Ru3(C0),(p3-a2nary zwitterionic carbon, C(2), to Ru(2) (Ru(2)-C(2)= 2.07 C=NCH2CH2CH2) (2) (vide infra). The other peak at (1)A). The long nitrogen to metal distances (N(l)-Ru(l) -14.89 ppm belongs to an as yet unidentified hydride = 3.04 A, N(WRu(2) = 2.90 A, N(l)-Ru(3) = 3.04 A) seem product. Repeated attempts to separate these two imto preclude any direct nitrogen-ruthenium bonding. purities from the major product by chromatographic Similarly, the short carbon-nitrogen double bond (C(2)methods failed. However recrystallization of the major N(1) = 1.31 (1) A) seems to preclude any significant K bonding interaction between this bond and the metal triangle. Overall this bonding scheme, with the non(5) (a) Deeming, A. J.; Day, M. W.; Hardcastle, K. I.; Arce, A. J.; bonding heteroatom suspended over the face of a metal DeSanctie, Y. Organometallics 1990,9,6. Day, M. W.; Deeming, A. J.; triangle, is unique in cluster chemistry but is reminiscent Arce, A. J.; Hardcastle,K. I.; DeSanctb, Y. Organometallics 1989,8,1408. carbon-nitrogen bond cleavage in the reactions of bis(dimethy1amino)methane with a variety of osmium clustem6 The C-N bond activation process observed for ordinary tertiary aliphatic amines under relatively mild reaction conditions seems unique to ruthenium so far, as the results reported previously and here illustrate.
I
x
1
(b) Deeming, A. J.; Hardcastle, K. I.; Minmian, H.; Arce, A. J.; De Sanctis, Y. J. Organomet. Chem. 1989, 368, 119. (c) Shapley, J. R.; Samkoff,D. E.; Bueno, C.; Churchill, M. R. Inorg. Chem. 1982,21,634. (6)Adams, R. D.; Babin, J. E. Organometallics 1988, 7,963 and references therein.
~
(7) Orpen, A. G. J . Chem. SOC.,Dalton Trans. 1980, 2509. (8)Catti, M.; Gervasio,G.; Mason, S.A. J. Chem. SOC.,Dalton Trans. 1977, 2260.
Organometallics, Vol. 10, No. 8, 1991 2745
Reactions of Tertiary Amines with Clusters
Table I. Crystal D a t a a n d Collection a n d Refinement Parameters 1
compd formula fw cryst system space group a,
C14H9NO&uS 638.44 monoclinic mlln 9.015 (2) 16.759 (4) 13.266 (3) 90 95.98 (2)
A
b, A
c, A a,deg 8, deg Y # deg
90
V,As
z
D d ,g/cm3
abs coeff p , cm-' data collect temp, OC radiation scan mode scan limits, deg scan speed, degfmin scan range, deg no. of data no. of data obsd no. of variables
Ra RWb
largest shiftlead weighting scheme highest peak in final diff map, e A-3 re1 transm coeff
"R= E W O l - l
1993 4 2.13 22.5 25 f 1 Mo K a w-2e 2
