CATIONIC BIS(ETA(2)-(PYRAZOL-1-YL)METHANE) AND TRIS(ETA(2)-(PYRAZOL-1-YL)METHANE) ACETYL COMPLEXES OF IRON(II) AND RUTHENIUM(II) - SYNTHESIS, CHARACTERIZATION, REACTIVITY, AND INTERIONIC SOLUTION STRUCTURE BY NOESY NMR-SPECTROSCOPY

The complexes trans,cis-M(PMe3)(2)(CO)(2)(Me)I (M = Fe and Ru, 1a,b) r eact with bis- and tris(pyrazol-1-yl)methane, in the presence of NaBPh 4, affording trans-[M(PMe3)(2)(CO)(COMe)-(pz(2)-CH2)]BPh4 (2a,b) and t rans-[M(PMe3)(2)(CO)(COMe)(eta(2)-pz(3)-CH)]BPh4 (3a,b), respectively (pz pyrazolyl ring). The reactions of 1b with 5,5'-Me-2-pz(2)-CH2 and 3,5'-Me-2-pz(2)-CH2 pro duce s-[Ru(PMe3)(2)(CO)(COMe)(5,5'-Me-2-pz(2)- CH2)]BPh4 (4) and s-[Ru(PMe3)(2)(CO)(COMe)(3,5'-Me-2-pz(2)-CH2)]BPh4 ( 5), respectively. A mixture of e3)(2)(CO)(2)(eta(1)-3,3'-Me-2-pz(2)-CH 2)(Me)]BPh4 (6) and s-[Ru(PMe3)(2)(CO)(COMe)(3,3'-Me-2-pz(2)-CH2)]BPh4 (7) is obtained from reaction of 1b and 3,3'-Me-2-pz(2)-CH2. The reac tions of 2-7 with nucleophiles either give back the starting complex ( Nu = I-) or analogous complexes (Nu Br- and Cl-) or produce decomposit ion products of the complexes (Nu = I-2, Br-2, Cl-2, and OMe-). The so lid state structures of 2b and 3b were obtained using single-crystal X -ray diffraction. For all complexes, 2-7 as well as complex 8 (analogu e to 2a, having a BF4- counterion instead of BPh4-), the ion-pair stru ctures and the localization of the counterion in solution with respect to the organometallic moiety were investigated by the detection of in terionic contacts in the H-1-NOESY and F-19{H-1}-HOESY NMR spectra.