Bis(pyrazol-1-yl)acetates as tripodal “scorpionate” ligands in transition metal carbonyl chemistry: syntheses, structures and reactivity of manganese and rhenium carbonyl complexes of the type [LM(CO)3] (L=bpza, bdmpza)

The coordination of the ligands bis(3,5-dimethylpyrazol-1-yl)acetate (bdmpza) and bis(pyrazol-1-yl)acetate (bpza) to Group VII metal carbonyls has been investigated. The compounds [LM(CO)3], where M=Mn, Re and L=bpza, bdmpza (2a–3b), have been synthesised. The new complexes [(bdmpza)Mn(CO)3] (2b), [(bpza)Re(CO)3] (3a) and [(bdmpza)Re(CO)3] (3b), and bis(pyrazol-1-yl)acetic acid (1a) have been characterised by single-crystal X-ray analyses. Based on IR-spectroscopic and structural data the electronic properties of these ligands are compared with those of Tp, TpMe2, Cp and Cp*. The reaction of [(bdmpza)Re(CO)3] (3b) with NOBF4 afforded [(bdmpza)Re(CO)2(NO)]BF4 (4).