Atom transfer reactions of (TTP)Ti(eta 2-3-hexyne): synthesis and molecular structure of trans-(TTP)Ti[OP(Oct)3]2.
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.
Thorman
J L
JL
Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111, USA.
Young
V G
VG
Boyd
P D
PD
Guzei
I A
IA
Woo
L K
LK