Reactivity of Tris(1‐pyrazolyl)methane Towards Ru⁰ Complexes

Abstract

By treating tris(1-pyrazolyl)methane (tpm) with suitably activated [Ru(cod)(cot)] and [Ru(cod)(nap)] (cod = η4-cycloocta-1,5-diene, cot = η6-cycloocta-1,3,5-triene, nap = η6-naphthalene) the (hydrido)RuII species [Ru(N2,N2',C5''-tpm)(cod)H] with cyclometalated tpm was obtained. This complex reacted with chloroform at room temperature to give\ud\ud [Ru(N2,N2',C5''-tpm)(cod)Cl] and dichloromethane. The coordination and symmetry of the novel complexes were elucidated by 1H and 13C NMR spectroscopy

C–H Activation of Pyrazolyl Ligands by Ru(II)

“…For example, phosphine ligands are often susceptible to cyclometalation. − Bidentate 2,2′-bipyridines have been reported to undergo “rollover” cyclometalation including reactions of Ir­(III), Rh­(III), Pd­(II), Pt­(II), and Au­(II) complexes. − The rollover cyclometalation occurs via rotation of the C–C bond to allow activation of the C(3)–H bond. Poly­(pyrazolyl)­alkane and poly­(pyrazolyl)­borate ligands with ≥ three pyrazolyl rings often coordinate to metals in a κ 3 - N , N , N mode; however, examples of intramolecular C–H activation at the 5-position of the pyrazolyl ring have been reported. − …”