Synthesis and Characterization of Bulky 1,3-Diamidopropane Complexes of Group 2 Metals (Be-Sr).

Reaction of lithium 1,3-diamidopropane Li 2 ( Trip NCN) ( Trip NCN=[{(Trip)NCH 2 } 2 CH 2 ] 2- , Trip=2,4,6-triisopropylphenyl) with BeBr 2 (OEt 2 ) 2 gave the diamido beryllium complex, [( Trip NCN)Be(OEt 2 )]. Deprotonation reactions between the bulkier 1,3-diaminopropane ( TCHP NCN)H 2 ( TCHP NCN=[{(TCHP)NCH 2 } 2 CH 2 ] 2- , TCHP=2,4,6-tricyclohexylphenyl) and magnesium alkyls afforded the adduct complexes [( TCHP NCN)Mg(OEt 2 )] and [( TCHP NCN)Mg(THF) 2 ], depending on the reaction conditions employed. Treating [( TCHP NCN)Mg(THF) 2 ] with the N-heterocyclic carbene :C{(MeNCMe) 2 } (TMC) gave [( TCHP NCN)Mg(TMC) 2 ] via substitution of the THF ligands. Reactions of ( Ar NCN)H 2 (Ar=Trip or TCHP) with Mg{CH 2 (SiMe 3 )} 2 , in the absence of Lewis bases, yielded the N-bridged dimers [{( Ar NCN)Mg} 2 ]. Salt metathesis reactions between alkali metal salts M 2 ( TCHP NCN) (M=Li or K) and CaI 2 or SrI 2 led to the THF adduct compounds [( TCHP NCN)Ca(THF) 3 ] and [( TCHP NCN)Sr(THF) 4 ], the differing number of THF ligands in which is a result of the different sizes of the metals involved. The described complexes hold potential as precursors to kinetically protected, low oxidation state group 2 metal species.