FERROCENE-BASED TRIS(1-PYRAZOLYL)BORATES - A NEW APPROACH TO HETEROOLIGOMETALLIC COMPLEXES AND ORGANOMETALLIC POLYMERS CONTAINING TRANSITION-METAL ATOMS IN THE BACKBONE

Starting from mono- and bifunctional ferrocene-based tris(1-pyrazolyl) borates, a novel route to oligonuclear complexes is presented, which i ncorporates transition metal centers differing substantially in their chemical nature, Both binuclear organometallics FcB(pz)(3)MLn (Fc: fer rocenyl. pz: 1-pyrazolyl, MLn: T1, 1-Tl; Mo(CO)(3)Li, 1-MoLi; Mo(CO)(2 )(eta(3)-methylallyl), 1-Mo; ZrCl3, 1-Zr) and trinuclear complexes 1,1 '-fc[B(pz)(3)MLn](2) (fc: ferrocenylene. MLn: T1, 2-Tl; Mo(CO)(3)Li, 2 -MoLi; Mo(CO)(2)(eta(3)-methylallyl), 2-Mo) have been prepared. The tr inuclear compound [FcB(4-SiMe(3)pz)(3)](2)Fe, 1-FeSi, has been investi gated as a model system for organometallic coordination polymers, cons isting of the bifunctional linker 1,1'-fc[B(Pz)(3)](2)(2-) and transit ion metal ions Mn+. X-ray crystallography shows 1-Tl to establish a po lymeric structure in the solid state, while 1-Mo features the usual tr identate coordination mode of the scorpionate ligand (C25H25BFeMoN6O2; a = 8.756(1) Angstrom, b = 12.154(1) Angstrom, c = 12.927(1) Angstrom , alpha = 105.26(1)degrees, beta = 102.29(1)degrees, gamma = 1.05.09(1 )degrees; triclinic space group <P(1)over bar>; Z = 2), With the excep tion of 1,2-Tl, the anodic oxidation of the ferrocene moiety is genera lly reversible; cyclic voltammetry measurements indicate the two Mo ce nters in 2-Mo and the two Fc moieties in 1-FeSi to be noncommunicating .