Sterically overloaded supersilylated main group elements and main group element clusters

Abstract

Supersilyl tBu 3Si behaves as a very bulky, chemically inert group. In fact, it exists (i) as an anion tBu 3Si − in supersilyl alkaline metals tBu 3SiM; (ii) as a short-lived radical tBu 3Si • after thermolizing tBu 3Si-Si tBu 3 or photolizing tBu 3Si-Hg-Si tBu 3; and (iii) as a strongly polarized “cation” in compounds tBu 3Si δ+-X δ− with partners X of weak Lewis basicity. By chemical transfer of these supersilyl species, supersilyl derivatives of almost all main group elements have so far been obtained. These include simple supersilylated compounds ( tBu 3Si) m EX n ( m = 1, 2; X = halogen and/or hydrogen as well as organyl) of main group elements E which, among others, are characterized by long SiE bond distances and large SiESi and SiEX bond angles. Over and above that, supersilylated compounds of main group element clusters are preparable. These include (i) those of the sixth group like ( tBu 3Si) 2E n (E = S, Se, Te); (ii) those of the fifth group like ( tBu 3Si) 2N 3H, ( tBu 3Si) 2N 4H 2, ( tBu 3Si) m P n ( m/n = 2/2, 2/4, 4/6, 2/7, 3/9), ( tBu 3Si) m P n Na p ( m/n/p = 2/3/1, 3/4/1, 2/4/2, 3/5/2, 4/8/4), ( tBu 3Si) 4Sb 4; (iii) those of the fourth group like ( tBu 3Si) 4E 4 (E = Si, Ge); and (iv) those of the third group like ( tBu 3Si) 4Al 4, ( tBu 3Si) 4E 2 (E = Al, In, Tl), ( tBu 3Si) 3Ga 2. In general, substitutions of hydrogens in low-valent main group element hydrides by supersilyl lead to a stabilization of the compounds. As a consequence of this, not only the supersilylated clusters mentioned but also unsaturated compounds of the heavier main group elements like tBu 2Si = N-Si tBu 3 become isolable.