Synthesis and characterization of ruthenium(II) pyrazole tertiary phosphine complexes

The product of the reaction of [RuCl2(PPh3)(3)] with two equivalents of pyr azole (Hpz) in toluene, when precipitated from a toluene/hexane mixture was characterised as [RuCl2(Hpz)(2)(PPh3)(2)] . 1/2C(6)H(14) (1); the same rea ction, effected in acetone, produced the acetone coordinated species [RuCl2 (Hpz)(Me2CO)(PPh3)(2)] (2). When the reaction was carried out using 3,5-dim ethylpyrazole (HDMpz), in either acetone or toluene as solvent, the yellow five-coordinate complex [RUCl2(HDMpz)(PPh3)(2)] (3) was produced. The bromo compounds [RuBr2(Hpz)(2)(PPh3)(2)] . 1/2C(6)H(14) (4) and [RuBr2(HDMpz)(PP h3)(2)] (5) have also been prepared using [RuBr2(PPh3)(3)] as precursor. At tempts to make the iodo analogues from [RuI2(PPh3)(2)](n), resulted in a sp ecies identified as [RuI2(HDMpz)(PPh3)(2)] on the basis of NMR and infrared measurements. The novel derivatives (1)-(5) have been characterised using microanalyses and infrared, H-1 and P-31 NMR spectroscopy. Reaction of (1) with CO resulted in displacement of Hpz to eventually produ ce cis-[RuCl2(CO)(2)(PPh3)(2)]. The reaction appeared to proceed through th e a monosubstituted product [RuCl2(CO)(Hpz)(PPh3)(2)], distinguished from s pectroscopic measurements. The reaction of (1) with oxygen is discussed.