Strontium Chemistry with Silicone Grease

Abstract

Abstract Reaction of Sr(2‐Me 2 N‐α‐Me 3 Si‐benzyl) 2 · (THF) 2 with one equivalent of DIPP(H)N–BH–N(H)DIPP (NBN–H 2 , DIPP = 2,6‐ i Pr‐phenyl) gave the strontium bora‐amidinate complex Sr(NBN) · (THF) 4 . Traces of silicone grease, however, can change the course of the reaction completely and gave the product {Sr[(DIPP)NSiMe 2 O] · THF} 4 ( 1 ) in a ca. 25 % yield. Complex 1 is a S 4 symmetric cluster with a Sr 4 O 4 core and four chelating amide side arms. From the mother liquor a second product could be isolated: the dimeric cluster [Sr(NBN‐SiMe 2 OSiMe 2 O) · THF] 2 ( 2 ). Whereas the synthesis of complex 2 is not reproducible, complex 1 can be prepared by deliberate addition of silicone grease. Also, it was found that Sr[N(SiMe 3 ) 2 ] 2 , 2,6‐diisopropylphenyl and cyclic hexamethyltrisiloxane can be used as the reagents. For reactions with silicone grease, a mechanism, in which silicone precoordinates the central Sr atom followed by nucleophilic Si–O bond fission is proposed.