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 heterocumulen es and (TTP)Ti(eta (2)-3-hexyne), 1 (TTP = meso-5,10,15,20-tetra-p-(olylpor phyrina dianion). The imido derivatives (TTP)Ti=NR (R = Pr-i, 2; Bu-i, 3) w ere produced upon treatment of complex 1 with (PrN)-Pr-i=C=(NPr)-Pr-i, (PrN CO)-Pr-i, or (BuNCO)-Bu-i. Reactions between complex 1 and CS2,(BuNCS)-Bu-i , or (BuNCSe)-Bu-i afforded the chalcogenido complexes, (TTP)Ti=Ch (Ch = Se , 4; S, 5). Treatment of complex 1 with 2 equiv of PEt3 yielded the bis(pho sphine) complex, (TTP)Ti(PEt3)2, 6. Although (TTP)Ti(eta (2)-3-hexyne) read ily abstracts oxygen from epoxides and sulfoxides, the reaction between 1 a nd O=P(Oct)(3) did not result in oxygen atom transfer. Instead, the paramag netic titanium(n) derivative (TTP)Ti[O=P(Oct)(3)](2), 7, was formed. The mo lecular structure of complex 7 was determined by single-crystal X-ray diffr action: Ti-O distance 2.080(2) Angstrom and Ti-O-P angle of 138.43(10)degre es. Estimates of Ti=O, Ti=S, Ti=Se, and Ti=NR bond strengths are discussed.