Organometallics 1995, 14, 3152-3153
3152
Ruthenium(I1)IMediatedReaction of Phenylacetylene with Primary Amines To Give Ruthenium(I1)-Isonitrile Complexes Claudio Bianchini," Maurizio Peruzzini, Antonio Romerosa, and Fabrizio Zanobini Istituto per lo Studio della Stereochimica ed Energetica dei Composti di Coordinazione, CNR, Via J . Nardi 39, 50132 Firenze, Italy Received April 18, 1995@ lated as pale orange crystals. However, without isolation, the following reaction step, which involves the addition of a slight excess of one of the primary amines listed in Scheme 1 at room temperature, can be also carried out. As a result, the corresponding aminocarbene derivatives fac,cis-[(PNP)RuC12{=C(NHR)(CH2Ph)}] are quantitatively obtained (R = CH2CH2CH3 (31, cyclo-C6H11(4), (R)-(+)-CH(Me)(Ph)(51, (R)-(-)-CH(Me)(Et) (61, (5')-(-)-CH(Me)(l-naphthyl) (7)). The presence of the aminocarbene ligands in 3-7 is unambiguously demonstrated by both lH (BNH 10.62-11.46) and 13C{'H} NMR spectroscopy (BRU-C 251.2-255.8; BCHzPh 56.5-59.5).4,5 The aminocarbene complexes, which can be isolated as yellow crystals, are stable in THF at room temperIn a previous article,' we reported that the Ru(I1) ature but quantitatively transform into the isonitrile complex mer,trans-[(PNP)RuC12(PPh3)l2 (1) assists the fac,cis-[(PNP)RuC12(CNR)] via elimination of complexes coupling of phenylacetylene with H2S to give the ql-2toluene ('H NMR, GC-MS) by stirring overnight at phenylethanethial ligand (PNP = CH~CHZCH~N(CH~reflux temperature in THF (only for the 1-naphthyl CH2PPh2)2). In this communication, we show that 1 complex 7 is a higher boiling solvent, such as monoglymediates the addition of primary amines to phenyme, required for a complete conversion to 12)(R = CH2lacetylene to yield isonitrile ligands. More importantly, CH2CH3 (81, cyclo-CBH11 (9), (R)-(+)-CH(Me)(Ph)(lo), the use of optically pure primary amines in the Ru(I1)(R)-(-)-CH(Me)(Et) (111, (SI-(-)-CH(Me)(1-naphthyl) assisted reaction herein described provides unprec(12)). All isonitrile complexes can be isolated as creamedented access to optically pure Ru(I1)-isonitrile comcolored crystals which are air-stable in both the solid plexes. Isonitriles are important substrates in organic state and solution and were characterized by spectroand organometallic syntheses but are generally difficult scopic techniques (IR (Nujol mull) v(CzN) 2117-2085 t o prepare by standard synthetic methods, owing to cm-l (vs); 13C{lH}NMR BR"-c=N 162.1-158.9).677 their propensity for spontaneous polymerization. Thus, alternative metal-assisted reactions have been devel(4)Dotz, K.H.; Fischer, H.; Hoffmann, P.; Kreissl, F. R.; Schubert, U.;Weiss, K. Transition Metal Carbene Complexes; Verlag Chemie: oped which involve the attack of primary amines on Weinheim, Germany, 1983. thio- and dithiocarbene ~omplexes.~ (5)All spectroscopic and analytical data for the aminocarbene complexes 3-7 have been provided a s supporting information. As a n Heating 1 in tetrahydrofuran (THF) with phenyexample, we report here analytical data and selected spectroscopic ~ ~64.23; P ~ RH,U : details for complex 5. Anal. Calcd for C ~ ~ H ~ ~ N Z C C, lacetylene at reflux gives the vinylidene complex fac,cis5.96;N, 3.19;C1,8.07. Found: C, 64.08;H, 5.89;N, 3.11;C1, 7.90.IR: [(PNP)RuC12{C=C(H)Ph}1(2).lComplex 2 can be isov ~ N H3460 ) cm-' (br, w). 31P{1H}NMR (22"C, CDZC12, 81.01 MHz),
Summary: The Ru(II) fragment [(PNP)RuCld assists the reaction of phenylacetylene with a variety of primary amines, including optically pure amines, to give Ru(I0isonitrile complexes (PNP = CH3CHzCHzN(CHzCHzPPhdd. The reaction is initiated by 1-alkyne to vinylidene tautomerization at the ruthenium center, followed by attack of the primary amine on the vinylidene ligand to give Ru(II) aminocarbenes of the formula fac,cis[(PNP)RuClz{=C(NHR)(CH~Ph)}/.The latter compounds thermally convert to the corresponding isonitrile complexes fac,cis-[~PNP)RuCl~CNR)/, while toluene is eliminated via C-C bond cleavage (R = CHzCHzCH3, cycloI, (R)-(f)-CH(Me)(Ph),(R14-J- CH(Me)(Et), (S)- (-) - CH(Me)(l -naphthyl)/.
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@Abstractpublished in Advance ACS Abstracts, July 1, 1995. (1)Bianchini, C.; Glendenning, L.; Peruzzini, M.; Romerosa, A,; Zanobini. F. J . Chem. Soc.. Chem. Commun. 1994.2219. (2)Bianchini, C.; InnoceGi, P.; Masi, D.; Peruzzini, M.; Zanobini, F. Gazr. Chim. Ital. 1992,122, 461. (3)McCormick, F. B.;Angelici, R. J. Inorg. Chem. 1979,18, 1231. McCormick, F. B.; Angelici, R. J . Inorg. Chem. 1981, 20, 1118. Pickering, R. A.; Angelici, R. J . Inorg. Chem. 1981,20, 2877. Steinmetz, A. L.; Hershberger, s. A.; Angelici, R. J. Organometallic 1984, 3,461. Albano, V. G.; Bordoni, S.; Braga, D.; Busetto, C.; Palazzi, A,; Zanotti, V. Angew. Chem., Int. Ed. Engl. 1991,30,847.Faraone, F.; Piraino, P.; Marsala, V.; Sergi, S. J. Chem. SOC.,Dalton Trans. 1977, 859.
= 29.7 Hz. 'H NMR (22 "C, AB system: h~ 50.32,OB 48.04,J(PAPB) CDzC12, 200.13 MHz): ONH 11.13 Ibr d, J ( H H ) = 9.6 Hzl, hCHpPh 4.80, 4.48 [ABsystem, J ( H H ) = 16.8 Hz, 2H1. 13C{lH} NMR (22"C, CD2Clz, 75.42MHz): ~ R " - c 255.3[t, 'J(CP) = 11.3Hzl, hcH2ph 58.6 [t, 3J(CP) = 4.6 Hzl. (6) See for example: Singleton, E.; Oosthuizen, M. E. Adu. Organomet. Chem. 1983,22,209. (7)All spectroscopic and analytical data for the isonitrile complexes 8- 12 have been provided a s supporting information. As an example, we report here analytical data and selected spectroscopic details for P~RU H,: 5.64;N, complex 10. Anal. Calcd for C ~ O H ~ ~ N ~ C ~C,Z 61.07; 3.56. Found: C, 60.94;H, 5.70;N, 3.38. IR v(C=N) 2100 cm-I (vs). 31P{1H)NMR (22 "C, CDC13, 81.01 MHz), AB system: OA 58.02,f)B 57.76,J ( P A ~=B26.1 ) Hz. 13C{lH} NMR (20"C, CDZC12, 75.42 MHz): = -5.93 ( C = 1.2,CHCld. Or" 160.9It, %J(CP) = 15.2Hzl.
0276-733319512314-3152$09.00/00 1995 American Chemical Society
Organometallics, Vol. 14, No. 7, 1995 3153
Communications
Scheme 1
r. t.
Me
I
8-12
CH3
The isonitrile ligands in complexes 8-12 are so strongly bound to ruthenium that their removal is not achieved either upon heating to 120 "C in monoglyme or upon pressurization under 15 atm of CO at 80 "C in THF solution. Current investigations center upon finding a method for the removal of the isonitriles from the Ru(I1) complexes. Preliminary results suggest that electrochemical oxidation may be successful.
3-7
Acknowledgment. This work was supported by Progetto Strategic0 "Tecnologie Chimiche Innovative", CNR, Rome, Italy, and the EC, Contract No. CHRX CT93-0147. A.R. thanks the Spanish Ministerio de Educacidn y Ciencia for a postdoctoral grant. Supporting InformationAvailable: Text giving experimental details of the synthesis and physicochemical characterization of the new complexes described in this paper (6 pages). Ordering information is given on any current masthead page.
OM950281X
