A 2,2′-bipyridyl calcium complex: synthesis, structure and reactivity studies?

Dalton Transactions Pub Date: 2023-04-25 DOI: 10.1039/D3DT00301A

Abstract

A 2,2′-bipyridyl calcium complex based on a tridentate ligand [CH3C(N-2,6-iPr2C6H3)CHC(CH3)NCH2CH2N(CH3)2]Ca(bipy)(THF) (1) was prepared by the reduction of {[CH3C(N-2,6-iPr2C6H3)CHC(CH3)NCH2CH2N(CH3)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 I2, PhCH2SSCH2Ph, PhCH2SeSeCH2Ph and 9-fluorenone, yielding the calcium iodide complex [CH3C(N-2,6-iPr2C6H3)CHC(CH3)NCH2CH2N(CH3)2]CaI(bipy) (2), calcium thiolate [CH3C(N-2,6-iPr2C6H3)CHC(CH3)NCH2CH2N(CH3)2]Ca(SCH2Ph)(bipy) (3), calcium selenolate [CH3C(N-2,6-iPr2C6H3)CHC(CH3)NCH2CH2N(CH3)2]Ca(SeCH2Ph)(bipy) (4), and calcium ketyl complex [CH3C(N-2,6-iPr2C6H3)CHC(CH3)NCH2CH2N(CH3)2]Ca[O-(9-C13H8˙)](bipy)·2THF (5·2THF), respectively. In addition, reactions of complex 5 with CS2, CH2[double bond, length as m-dash]CHCH2Br and PhCH2Br give the corresponding dimeric bis(thiolate) complex {[S2CC(CMe(NAr))C(Me)NCH2CH2NMe2]Ca(DME)}2 (6), dimeric calcium bromide complex {[(9-CH2[double bond, length as m-dash]CHCH2-C13H8-9)-O]CaBr(THF)(bipy)}2 (7) and {[(9-C6H5CH2-C13H8-9)-O]CaBr[O-(9-C13H8)](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.

Graphical abstract: A 2,2′-bipyridyl calcium complex: synthesis, structure and reactivity studies
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