Syntheses of Cationic Lead(II) and Tin(II) Complexes Containing Tris(pyrazolyl)methane Ligands. Control of Stereochemistry by Variation in Ligand Substitution

Abstract

The addition of 2 equiv of HBF4·Et2O to a THF suspension of Pb(acac)2 (acac = acetylacetonate) followed by addition of 1 molar equiv of the tris(pyrazolyl)methane ligand HC(3,5-Me2pz)3 (pz = pyrazolyl ring) results in the immediate precipitation of {[HC(3,5-Me2pz)3]Pb}(BF4)2 (1). The complex {[HC(3,5-Me2pz)3]2Pb}(BF4)2 (2) was prepared by precipitation from an acetone solution of 1 containing an excess of HC(3,5-Me2pz)3. Both {[HC(pz)3]2Pb}(BF4)2 (3) and {[HC(pz)3]Pb}(BF4)2 (4) are prepared by the addition of the respective equivalent amounts of HC(pz)3 to the HBF4·Et2O−Pb(acac)2 THF solution. The lead ion in 1 is three coordinate with normal Pb−N distances ranging from 2.379(14) to 2.434(16) A (average = 2.41 A). The six-coordinate lead ion in 2 is in a trigonally distorted octahedral environment with equivalent Pb−N bond distances (2.635(7) A). The lone pair on lead is stereochemically inactive and does not appear to influence the structure. The lead ion in 3 is in an asymmetric six-coordinate environme...