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 (la) 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, Tp(Me2), Cp and Cp*. The reaction of [(bdmpza)Re(CO)(3)] (3b) with NOBF4 afforded [(bdmpza)Re(CO)(2)(NO)]BF4 (4). (C) 2001 Elsevier Science B.V. All rights reserved.