Homo- and Heteropolynuclear Clusters of Phosphine Triphenolates

The synthesis and structural characterization of a series of homo- and heteropolynudear clusters constructed with a potentially tetradentate phosphine triphenolate ligand are presented. Treatment of tris(3,5-di-tert-butyl-2-hydroxyphenyl)phosphine (H-3[O3P) with 3 equiv of nBuLi in diethyl ether at -35 degrees C affords hexanuclear Li-6[O3P](2)(OEt2)(2) (1) as colorless crystals. In situ lithiation of H-3[O3P] with 3 equiv of nBuLi in THF at -35 degrees C followed by metathetical reactions with MnCl2 or NiCl2(DME) gives crystals of forest green pentanuclear MnLi4[O3P](2)(THF)(3) (2) or dark brown tetranuclear Ni2Li2[O3P](2)(THF)(2) (3), respectively. Alkane elimination of ZnR2 (R = Me, Et) with H3[O3P] in THF at 25 degrees C generates high yields of colorless crystalline trinuclear Zn-3[O3P](2)(THF)(2) (4). The cluster structures of 1-4 were all determined by single crystal X-ray diffraction studies. These molecules represent the first examples of metal complexes supported by phosphine triphenolate derivatives. The cluster 2 contains a paramagnetic core of high spin Mn(II) (S = 5/2) as indicated by solution and solid state magnetic susceptibility measurements.