Reactivity of the TpRu(HN=CPh2)(PPh3)−Azido complex and Insertion of Methylene into the Tp B−H Bond

Abstract

• We report [3+2] cycloaddition reactions of alkyne with the ruthenium azido complex. • The stable triazolato and tetrazolato products obtained in all cases were N (2)-bound. • We report that during protonation of ruthenium azido complex, methylene insertion accidentally took place, to yield unusual boron-methylated product. • Their structures are elucidated by IR, NMR and X-ray crystallography. Herein, we report on the reactivity of an Ru(II) azido complex allowing the facile synthesis of further interesting complexes. Starting from the parent chlorido complex (HN=CPh 2 )[Ru]−Cl { 1 , [Ru] = Tp(PPh 3 )Ru; Tp = HB(pz) 3 , pz = pyrazolyl)} the title complex (HN=CPh 2 )[Ru]−N 3 ( 2 ) was obtained upon reaction with NaN 3 . The N (2)-bound 4,5-bis-(methoxycarbonyl)-1,2,3-triazolato complex (HN=CPh 2 )[Ru]−{N 3 C 2 (CO 2 Me) 2 } ( 3 ) was obtained from reaction of 2 with dimethyl acetylene dicarboxylate (DMAD). Protonation of 3 with HCl afforded the N -coordinated triazolato complex {HN 3 C 2 (CO 2 Me) 2 }[Ru]−Cl ( 4 ). Reaction of CS 2 with 2 produced the thiocyanato complex (HN=CPh 2 )[Ru]−NCS ( 5 ). The Ru tetrazolato complex (HN=CPh 2 )[Ru]−N 4 C[C(CN)=C(CN) 2 ] ( 6 ) was prepared from 2 and tetracyanoethylene (TCNE). The reaction of 2 with HX gave the 17-electron Ru(III) complexes (Cl)[Ru]−X ( 7a , X = Cl ; 7b , X = Br) and the Ru(II) complexes containing the methyl tris(pyrazolyl)borate ligand Me Tp(PPh 3 )(HN=CPh 2 )Ru−X ( 8a , X = Cl ; 8b , X = Br), as a result of an unusual methylene insertion into the B−H bond of the Tp ligand with the CH 2 Cl 2 solvent as the assumed source for the methylene. The structures of 4, 5, 7a, 7b and 8b had been determined by X-ray diffraction analysis.