Synthesis and Structure of [η<sup>5</sup>-1,2,4-(Me<sub>3</sub>Si)<sub>3</sub>C<sub>5</sub>H<sub>2</sub>]<sub>2</sub>Th(bipy) and Its Reactivity toward Small Molecules
Shichun Wang, Dongwei Wang, Yi Heng, Tongyu Li, Wanjian Ding, Guofu Zi, Marc D. Walter
Abstract
Halide exchange of (Cp 3tms ) 2 ThCl 2 ( 1; Cp 3tms = η 5 -1,2,4-(Me 3 Si) 3 C 5 H 2 ) with Me 3 SiI furnishes (Cp 3tms ) 2 ThI 2 ( 2 ), which is then reduced with potassium graphite (KC 8 ) in the presence of 2,2′-bipyridine to give the thorium bipyridyl metallocene (Cp 3tms ) 2 Th(bipy) ( 3 ) in good yield. Complex 3 was fully characterized and readily reacted with various small molecules. For example, 3 may serve as a synthetic equivalent for the (Cp 3tms ) 2 Th(II) fragment when exposed to CuI, Ph 2 S 2, organic azides, and CS 2 . Moreover, upon the addition of thiobenzophenone Ph 2 CS, p -methylbenzaldehyde ( p -MeC 6 H 4 )CHO, benzophenone Ph 2 CO, amidate PhCONH( p -tolyl), seleno-ketone ( p, p ′-dimethoxy), selenobenzophenone ( p -MeOPh) 2 CSe, di( p -tolyl)methanimine ( p -tolyl) 2 C═NH, 1,2-di(benzylidene)hydrazine (PhCH═N) 2, and nitriles PhCN, PhCH 2 CN, and Ph 2 CHCN C–C coupling results to give (Cp 3tms ) 2 Th[(bipy)(Ph 2 CS)] ( 8 ), (Cp 3tms ) 2 Th[(bipy)( p -MePhCHO)] ( 9 ), (Cp 3tms ) 2 Th[(bipy)(Ph 2 CO)] ( 10 ), (Cp 3tms ) 2 Th[(bipy){( p -tolylNH)(Ph)CO}] ( 11 ), (Cp 3tms ) 2 Th[(bipy){( p -MeOPh) 2 CSe}] ( 12 ), (Cp 3tms ) 2 Th[(bipy){( p -tolyl) 2 CNH}] ( 13 ), (Cp 3tms ) 2 Th[(bipy)(PhCHNN═CHPh)] ( 14 ), (Cp 3tms ) 2 Th[(bipy)(PhCN)] ( 16 ), (Cp 3tms ) 2 Th[(bipy)(PhCH 2 CN)] ( 17 ), and (Cp 3tms ) 2 Th[(bipy)(Ph 2 CHCN)] ( 18 ), respectively. However, when thiazole is added to 3, the dimeric sulfido complex [(Cp 3tms ) 2 Th] 2 [μ-(bipy)CH 2 NCHCHS] 2 ( 15 ) can be isolated. Moreover, the addition of isonitriles such as Me 3 CNC and PhCH 2 NC to 3 results in C–N bond cleavage and C–C coupling processes to form the thorium isocyanido amido complexes (Cp 3tms ) 2 Th[4-(Me 3 C)bipy](NC) ( 19 ) and (Cp 3tms ) 2 Th[4-(PhCH 2 )bipy](NC) ( 20 ), respectively. Nevertheless, upon exposure of 3 to (trimethylsilyl)diazomethane Me 3 SiCHN 2, the bis-amido complex (Cp 3tms ) 2 Th[5,6-(Me 3 SiCH)bipy] ( 21 ), concomitant with N 2 release, is isolated.