A 2,2'-bipyridyl calcium complex: synthesis, structure and reactivity studies.

A 2,2'-bipyridyl calcium complex based on a tridentate ligand [CH 3 C(N-2,6- i Pr 2 C 6 H 3 )CHC(CH 3 )NCH 2 CH 2 N(CH 3 ) 2 ]Ca(bipy)(THF) (1) was prepared by the reduction of {[CH 3 C(N-2,6- i Pr 2 C 6 H 3 )CHC(CH 3 )NCH 2 CH 2 N(CH 3 ) 2 ]CaI(THF)} 2 with potassium graphite in the presence of 2,2'-bipyridine (bipy). Complex 1 is a good Ca(I)synthon, as shown by its reactivity with I 2 , PhCH 2 SSCH 2 Ph, PhCH 2 SeSeCH 2 Ph and 9-fluorenone, yielding the calcium iodide complex [CH 3 C(N-2,6- i Pr 2 C 6 H 3 )CHC(CH 3 )NCH 2 CH 2 N(CH 3 ) 2 ]CaI(bipy) (2), calcium thiolate [CH 3 C(N-2,6- i Pr 2 C 6 H 3 )CHC(CH 3 )NCH 2 CH 2 N(CH 3 ) 2 ]Ca(SCH 2 Ph)(bipy) (3), calcium selenolate [CH 3 C(N-2,6- i Pr 2 C 6 H 3 )CHC(CH 3 )NCH 2 CH 2 N(CH 3 ) 2 ]Ca(SeCH 2 Ph)(bipy) (4), and calcium ketyl complex [CH 3 C(N-2,6- i Pr 2 C 6 H 3 )CHC(CH 3 )NCH 2 CH 2 N(CH 3 ) 2 ]Ca[O-(9-C 13 H 8 ˙)](bipy)·2THF (5·2THF), respectively. In addition, reactions of complex 5 with CS 2 , CH 2 CHCH 2 Br and PhCH 2 Br give the corresponding dimeric bis(thiolate) complex {[S 2 CC(CMe(NAr))C(Me)NCH 2 CH 2 NMe 2 ]Ca(DME)} 2 (6), dimeric calcium bromide complex {[(9-CH 2 CHCH 2 -C 13 H 8 -9)-O]CaBr(THF)(bipy)} 2 (7) and {[(9-C 6 H 5 CH 2 -C 13 H 8 -9)-O]CaBr[O-(9-C 13 H 8 )](bipy)} 2 (8). These results demonstrated that the calcium ketyl complex 5 can also be employed as a single-electron transfer reagent. All the new compounds were characterized by various spectroscopic methods, and their solid-state structures were further confirmed by single-crystal X-ray diffraction analyses.