RESUMO
Atom and group transfer reactions were found to occur between heterocumulenes and (TTP)Ti(eta 2-3-hexyne), 1 (TTP = meso-5,10,15,20-tetra-p-tolylporphyrinato dianion). The imido derivatives (TTP)Ti=NR (R = iPr, 2; tBu, 3) were produced upon treatment of complex 1 with iPrN=C=NiPr, iPrNCO, or tBuNCO. Reactions between complex 1 and CS2, tBuNCS, or tBuNCSe afforded the chalcogenido complexes, (TTP)Ti=Ch (Ch = Se, 4; S, 5). Treatment of complex 1 with 2 equiv of PEt3 yielded the bis(phosphine) complex, (TTP)Ti(PEt3)2, 6. Although (TTP)Ti(eta 2-3-hexyne) readily abstracts oxygen from epoxides and sulfoxides, the reaction between 1 and O=P(Oct)3 did not result in oxygen atom transfer. Instead, the paramagnetic titanium(II) derivative (TTP)Ti[O=P(Oct)3]2, 7, was formed. The molecular structure of complex 7 was determined by single-crystal X-ray diffraction: Ti-O distance 2.080(2) A and Ti-O-P angle of 138.43(10) degrees. Estimates of Ti=O, Ti=S, Ti=Se, and Ti=NR bond strengths are discussed.
RESUMO
Titanium porphyrin hydrazido complexes (TTP)Ti = NNR2 (TTP = meso-tetra-p-tolylporphyrinato dianion; R = Me (1), Ph (2)) were synthesized by treatment of (TTP)TiCl2 with 1,1-disubstituted hydrazines H2NNR2 (R = Me, Ph) in the presence of piperdine. The nucleophilic character of the hydrazido moiety was demonstrated in the reactions of complexes 1 and 2 with p-chlorobenzaldehyde, which yielded the titanium oxo complex (TTP)-Ti = O and the respective hydrazones. Protonation of complexes 1 and 2 with phenol or water produced the 1,1-disubstituted hydrazine along with (TTP)Ti(OPh)2 or (TTP)Ti = O, respectively. Similar reactivity of p-chlorobenzaldehyde and phenol with (TTP)Ti = NiPr, 3, was observed. The reaction of complex 3 with nitrosobenzene cleanly formed the azo compound iPrN = NPh and the terminal oxo product (TTP)Ti = O.
RESUMO
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.
