Addition and metathesis reactions of zirconium and hafnium imido complexes.

The zirconium and hafnium imido metalloporphyrin complexes (TTP)M = NArtPr (TTP = meso-5,10,15,20-tetra-p-tolylporphyrinato dianion; M = Zr (1), Hf; AriPr = 2,6-diisopropylphenyl) were used to mediate addition reactions of carbonyl species and metathesis of nitroso compounds. The imido complexes react in a stepwise manner in the presence of 2 equiv of pinacolone to form the enediolate products (TTP)M[OC(tBu)CHC(tBu)(Me)O] (M = Zr (2), Hf (3)), with elimination of H2NAriPr. The bis(mu-oxo) complex [(TTP)ZrO]2 (4) is formed upon reaction of (TTP)Zr = NAriPr with PhNO. Treatment of compound 4 with water or treatment of compound 2 with acetone produced the (mu-oxo)bis(mu-hydroxo)-bridged dimer [(TTP)Zr]2(mu-O)(mu-OH)2 (5). Compounds 2, 4, and 5 were structurally characterized by single-crystal X-ray diffraction.