HOW TO STEER THE COORDINATION OF ZINC-COM PLEXES - INVESTIGATIONS WITH HYDRIDOTRIS(3-PHENYLPYRAZOLYL)BORATE AS A LIGAND

The crystal structure analyses of the zinc complexes L(Ph)ZnCl (A) and Zn(LPh)2 (B) of the potentially tridentate nitrogen ligand L(Ph)- = H B(3-Phpz)3 (3-Phpz = 3-Phenylpyrazolyl) unexpectedly show tetrahedral coordination of the metal ion in both cases. The bisligand zinc comple x B is formed by decomposition of unstable hydroxy and alkoxy complexe s of the formula L(Ph)ZnOR. As a further product of that reaction a co mplex of the formula [eta3-HB(3-Phpz)3Zn(3-PhpzH)]+ClO4- could be iden tified, which is a first example for the cationic species [L(Ph)Zn(neu tral ligand)]+. A crystallizes in the trigonal system with lattice con stants of a = 11.449(2) and c = 11.365(2) angstrom, space group P3BAR, Z = 2, d(calc). 1.396 mg/mm3. B crystallizes in the orthorhombic syst em with a = 22.675(3), b = 10.797(2), and c = 19.699(3) angstrom, spac e group Pbcn; Z = 4, d(calc) = 1.306 Mg/MM3 . The crystal structures w ere determined from 1 687 (A) and 2 341 (B) observed X-ray data and re fined to R = 0.03 and 0.04, respectively. A was characterized as a chl orotripod complex with symmetry 3-C3 and a distorted tetrahedral coord ination of the Zn atom (angle Cl-ZN-N 122.9(1)-degrees and N-Zn-N' 93. 3(1)-degrees), while B was identified as a bisligand complex with symm etry 2-C2 and again a distorted tetrahedral coordination of the Zn ato m (angles N-Zn-N 101.5(1) up to 118.9(1)-degrees).