3152 Organometallics zyxwvu 1995, 14, 3152-3153 Ruthenium(I1)IMediated Reaction 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@ Summary: The Ru(II) fragment [(PNP)RuCld assists the reaction of phenylacetylene with zyxwvut a variety of primary amines, including optically pure amines, to give Ru(I0- isonitrile complexes (PNP zyxwvutsr = CH3CHzCHzN(CHzCHz- PPhdd. The reaction is initiated by 1-alkyne to vinyl- idene 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 com- pounds thermally convert to the corresponding isonitrile complexes fac,cis-[~PNP)RuCl~CNR)/, while toluene is eliminated via C-C bond cleavage (R = CHzCHzCH3, cyclo- I, (R)-(f)-CH(Me)(Ph), (R14-J- CH(Me)(Et), zyxwvu (S) - (-) - CH(Me)(l-naphthyl)/. In a previous article,' we reported that the Ru(I1) complex zyxwvuts mer,trans-[(PNP)RuC12(PPh3)l2 (1) assists the coupling of phenylacetylene with H2S to give the ql-2- phenylethanethial ligand (PNP = CH~CHZCH~N(CH~- CH2PPh2)2). In this communication, we show that 1 mediates the addition of primary amines to pheny- lacetylene to yield isonitrile ligands. More importantly, the use of optically pure primary amines in the Ru(I1)- assisted reaction herein described provides unprec- edented access to optically pure Ru(I1)-isonitrile com- plexes. Isonitriles are important substrates in organic and organometallic syntheses but are generally difficult to prepare by standard synthetic methods, owing to their propensity for spontaneous polymerization. Thus, alternative metal-assisted reactions have been devel- oped which involve the attack of primary amines on thio- and dithiocarbene ~omplexes.~ Heating 1 in tetrahydrofuran (THF) with pheny- lacetylene at reflux gives the vinylidene complex fac,cis- [(PNP)RuC12{C=C(H)Ph}1(2).l Complex 2 can be iso- ~ ~ ~ ~ ~~~ @Abstract published 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, zyxwvutsrqp 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. Stein- metz, 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. 0276-733319512314-3152$09.00/0 lated as pale orange crystals. However, without isola- tion, 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 aminocar- bene derivatives fac,cis-[(PNP)RuC12{=C(NHR)(CH2- Ph)}] 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 temper- ature but quantitatively transform into the isonitrile complexes fac,cis-[(PNP)RuC12(CNR)] via elimination of toluene ('H NMR, GC-MS) by stirring overnight at reflux temperature in THF (only for the 1-naphthyl complex 7 is a higher boiling solvent, such as monogly- me, required for a complete conversion to 12) (R = CH2- CH2CH3 (81, cyclo-CBH11 (9), (R)-(+)-CH(Me)(Ph) (lo), (R)-( - )-CH(Me)(Et) (1 11, (SI-( - )-CH(Me)( 1-naphthyl) (12)). All isonitrile complexes can be isolated as cream- colored crystals which are air-stable in both the solid state and solution and were characterized by spectro- scopic techniques (IR (Nujol mull) v(CzN) 2117-2085 cm-l (vs); 13C{lH}NMR BR"-c=N 162.1-158.9).677 (4) Dotz, K. H.; Fischer, H.; Hoffmann, P.; Kreissl, F. R.; Schubert, U.; Weiss, K. Transition Metal Carbene Complexes; Verlag Chemie: Weinheim, Germany, 1983. (5) All spectroscopic and analytical data for the aminocarbene complexes 3-7 have been provided as supporting information. As an example, we report here analytical data and selected spectroscopic details for complex 5. Anal. Calcd for C ~ ~ H ~ ~ N Z C ~ ~ P ~ R U : C, 64.23; H, 5.96; N, 3.19; C1,8.07. Found: C, 64.08; H, 5.89; N, 3.11; C1, 7.90. IR: v~NH) 3460 cm-' (br, w). 31P{1H} NMR (22 "C, CDZC12, 81.01 MHz), AB system: h~ 50.32, OB 48.04, J(PAPB) = 29.7 Hz. 'H NMR (22 "C, CDzC12, 200.13 MHz): ONH 11.13 Ibr d, J(HH) = 9.6 Hzl, hCHpPh 4.80, 4.48 [AB system, J(HH) = 16.8 Hz, 2H1. 13C{ lH} NMR (22 "C, CD2- Clz, 75.42 MHz): ~R"-c 255.3 [t, 'J(CP) = 11.3 Hzl, hcH2ph 58.6 [t, 3J(CP) = 4.6 Hzl. (6) See for example: Singleton, E.; Oosthuizen, M. E. Adu. Orga- nomet. Chem. 1983,22, 209. (7) All spectroscopic and analytical data for the isonitrile complexes 8- 12 have been provided as supporting information. As an example, we report here analytical data and selected spectroscopic details for complex 10. Anal. Calcd for C ~ O H ~ ~ N ~ C ~ Z P ~ R U : C, 61.07; H, 5.64; N, 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(PA~B) = 26.1 Hz. 13C{ lH} NMR (20 "C, CDZC12, 75.42 MHz): Or" 160.9 It, %J(CP) = 15.2 Hzl. = -5.93 (C = 1.2, CHCld. 0 1995 American Chemical Society