Reactivity of ruthenium(II) complexes with 1-hydroxymethyl- or 1-benzyl-3,5-dimethylpyrazole and similar functionalized bipyrazoles. X-Ray crystal structure of carbonylchlorohydrido(3,5-dimethylpyrazole-N2)-bis(triphenylphosphine)ruthenium(II)

Abstract

The complexes [RuCl₂(PPh₃)₃], [RuClH(PPh₃)₃], and [Ru(CO)ClH(PPh₃)₃] react with 1-hydroxymethyl-3,5-dimethylpyrazole to give in all cases carbonylchlorohydrido(3,5-dimethylpyrazole-N²)bis(triphenylphosphine)ruthenium(II)(1a) as product. The substitution of the 1-hydroxymethyl group by hydrogen in the pyrazole ring is characteristic of these reactions. Similar reactions take place with 1,1′-di( hydroxymethyl)-3,3′,5,5′-tetramethyl-4,4′-bipyrazole and -methylenedipyrazole to give binuclear bipyrazole-bridged complexes [{Ru(CO)ClH(PPh₃)₂}₂(µ-L′)][L′= 3,3′,5,5′-tetramethyl-4,4′-bipyrazole or -methylenedipyrazole respectively]. No reaction occurs with 1 -benzyl-3,5-dimethylpyrazole nor with the corresponding 1,l′-dibenzylbipyrazole. We have determined the crystal structure of [Ru(CO)ClH(Hdmpz)(PPh₃)₂](Hdmpz = 3,5-dimethylpyrazole). It crystallizes in the space group P2₁n with a= 9.687(3), b= 16.244(6), c= 24.022(6)Å, β= 94.19(2)°, and Z= 4. Standard anisotropic least-squares refinement gave R= 0.060 for 3 920 observed reflections. The ruthenium atom is six-co-ordinated in a distorted octahedral geometry with the atom pairs (P,P), (Cl,H), and (C,N) in trans positions.