Synthesis,characterization, and structures of New Titanocene Isoselenocyanato Complexes

The complexes [Ti(η⁵-C₅H₄R)₂(NCSe)₂] [R = Me ( 1 ), SiMe₃ ( 2 ), or SiEt₃ ( 3 )] were prepared from the corresponding dichlorides with KSeCN in acetone; the oxygen-bridged complex [Ti(η⁵-C₅H₄Me)₂(NCSe)]₂O ( 4 ) was formed by air oxidation of ( 1 ). All complexes were characterized by elemental microanalysis and by IR, ¹H NMR, and mass spectroscopies. An X-ray analysis of ( 1 ) and ( 4 ) confirms the results of IR studies that these complexes contain N-bonded selenocyanate ligands. In molecules ( 1 ) and ( 4 ) there is a pseudotetrahedral arrangement about each titanium. The N? C? Se chains are linear with normal N? C and C? Se bond distances. The dimer ( 4 ) contains an approximately linear Ti? O? Ti bridge (angle 173.4º) with a Ti? O bond distance of 1.838 Å. The structural results are compared with those in related compounds.