Metal-Assisted Aldol-Type Condensation of Two Acetimino Ligands To Give a 4-Imino-2-methylpentan-2-amino Rhodium(III) Complex Jose ´ Vicente,* Marı ´a-Teresa Chicote, † Rita Guerrero, Inmaculada Vicente-Herna ´ ndez, and Miguel M. Alvarez-Falco ´n Grupo de Quı ´mica Organometa ´ lica, Departamento de Quı ´mica Inorga ´ nica, Facultad de Quı ´mica, Universidad de Murcia, Apartado 4021, E-30071 Murcia, Spain Peter G. Jones ‡ Institut fu ¨ r Anorganische und Analytische Chemie der Technischen Universita ¨ t, Postfach 3329, 38023 Braunschweig, Germany Delia Bautista Universidad de Murcia, SACE, Apartado 4021, E-30071 Murcia, Spain Received July 1, 2005 Summary: The intramolecular aldol-like condensation of two acetimino ligands has been observed for the first time to occur in [Rh(Cp*)Cl(NHdCMe 2 ) 2 ]ClO 4 (1‚ClO 4 ), under catalytic or stoichiometric reaction conditions, to give [Rh(Cp*)Cl{N,N-NHdC(Me)CH 2 C(Me) 2 NH 2 }]X (2‚ X, X ) Cl, ClO 4 ). The crystal structures of 1‚ClO 4 and 2‚Cl have been determined. Acetimine is among the products resulting from the condensation of acetone and ammonia. 1 However, as it decomposes after short periods of storage 2 and it is difficult to isolate 3 and handle, few complexes with this ligand have been reported; none of them were prepared using acetimine itself or a general method. 4,5 We have prepared [Ag(NHdCMe 2 ) 2 ]ClO 4 and are exploring its potential application as a general reagent for the synthesis of acetimino metal complexes. 6 Thus, its reaction with [Rh(Cp*)Cl(μ-Cl)] 2 (2:1; Cp* ) η 5 -C 5 Me 5 ) gave the first acetimino Rh(III) complex, [Rh(Cp*)Cl- (NHdCMe 2 ) 2 ]ClO 4 (1‚ClO 4 ) (Scheme 1). An attempt to prepare [Rh(Cp*)Cl 2 (NHdCMe 2 )] by reacting 1‚ClO 4 with PPNCl (1:1) unexpectedly produced the complex [Rh(Cp*)Cl(imam)]Cl (2‚Cl; imam ) κ 2 -N,N-4-imino-2- methylpentan-2-amino) (Scheme 1). The homologous perchlorate salt [Rh(Cp*)Cl(imam)]ClO 4 (2‚ClO 4 ) was obtained in almost quantitative yield from 2‚Cl and AgClO 4 (1:1, acetone, 30 min) or, more surprisingly, by stirring 1‚ClO 4 under a CO atmosphere (1.8 bar, ac- etone, room temperature, 24 h), or by treating it with a catalytic amount of Ph 2 CdNH (1:0.1, acetone, 24 h). The complex 2‚ClO 4 is the major product in the reactions of 1‚ClO 4 with AsPh 3 (1:1, acetone, 24 h) and with a catalytic amount of SMe 2 (1:0.1, acetone, 24 h) or on heating it to 70 °C in solution (CH 2 Cl 2 or acetone, in a Carius tube) for 24 h (Scheme 1). However, no conden- sation of the acetimine ligands takes place when 1‚ClO 4 is stirred in acetone for 24 h at room temperature or reacted with PPh 3 , XyNC, or [Ag(NHdCMe 2 ) 2 ]ClO 4 (1:1). Metal complexes of the imam ligand are very scarce indeed, and only nine of them (including the Br - , NO 3 - , and ClO 4 - salts of the [Ni(imam) 2 ] 2+ cation) have been fully characterized by their X-ray crystal structures. 7 They were obtained by reacting various ammine com- plexes of Co(III) 8 or Ni(II) with acetone, 9,10 by treating Cu(NO 3 ) 2 10 or Pd(II) complexes 5 with acetone and am- monia, or by reacting Ru(III) complexes 11 with am- monium thiobenzoate and acetone or with ammonia and * To whom correspondence should be addressed. E-mail: jvs1@um.es. WWW: http://www.um.es/gqo. † E-mail: mch@um.es. ‡ E-mail: p.jones@tu-bs.de. (1) Bradbury, R. B.; Hancox, N. C.; Hatt, H. H. J. Chem. Soc. 1947, 1394. Murayama, K.; Morimura, S.; Amakasu, O.; Toda, T.; Yamao, E. Chem. Abstr. 1969, 70, 324. Murayama, K.; Morimura, S.; Amakasu, O.; Toda, T.; Yamao, E. Nippon Kagaku Zasshi 1969, 90, 296. (2) Findeisen, K.; Heitzer, H.; Dehnicke, K. Synthesis 1981, 702. 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