Cyclooctatetraene poly(azolyl)borate complexes of zirconium:: [Zr(κ2-L)Cl(η-C8H8)] (L = H2B(pz)2, HB(pzMe2)3, H2B(mt)2; pz = pyrazolyl, mt = methimazolyl)

The reactions of [ZrCl2(thf)(eta-C8H8)] with K[H2B(pz)(2)], K[HB(pzMe(2))(3)], and Na[H2B(mt)(2)] (pz = pyrazolyl, mt = methimazolyl) provide the complexes [Zr(kappa(2)-L)Cl(eta-C8H8)] (L = H2B(pz)(2), HB(pzMe(2))(3), H2B(mt)(2)). In each case the metal is electronically unsaturated (16 electrons), despite the capability, in principle, of each of the ligands L to increase the metal coordination number. The only product isolated so far from the corresponding reaction with K[H2B(pzMe(2))(2)] is, however, the organometallic oxide cluster [Zr-4(mu-O)(4)(mu-Cl)(2)Cl-2(eta-C8H8)(4)].