Synthesis and Characterization of Rigid Ditopic N-Heterocyclic Benzobisgermylenes and -stannylenes

Abstract

A rigid ditopic benzobisgermylene, 4a, was prepared by the reaction of the 1,2,4,5-tetra(alkylamine)­benzene 3a and Ge­[N­(SiMe3)2]2. The analogous reaction of two 1,2,4,5-tetra(alkylamine)­­benzenes, 3b,c, with Sn­[N­(SiMe3)2]2 led to the oxidation of the tetramine ligand and formation of N-alkyl-2-(alkylamine)-N′-alkyl-5-(alkylamine)-1,4-benzoquinonediimines (5b,c) and tin(0). The p-benzoquinonediimines 5b,c subsequently react with remaining Sn­[N­(SiMe3)2]2 to yield distannylene complexes of type [N-alkyl-2-(alkylamino)-N′-alkyl-5-(alkylamino)-1,4-benzoquinonediimine]­di­[bis­(trimethylsilyl)­aminotin­(II)] (6b,c). The 2,5-di­(alkylamine)-1,4-benzoquinonediimines 5b,c can also be obtained directly by aerial oxidation of the 1,2,4,5-tetrakis­(alkylamine)­benzenes 3b,c. They react with two equivalents of Sn­[N­(SiMe3)2]2 also under transmetalation and formation of [N-alkyl-2-(alkylamino)-N′-alkyl-5-(alkylamino)-1,4-benzoquinonediimine]­di­[bis­(trimethylsilyl)­aminotin­(II)] (6b,c). The molecular structures of 3b, 4a, 6b, and 6c have been established by X-ray diffraction.

A Tin Analogue of Carbenoid: Isolation and Reactivity of a Lithium Bis(imidazolin‐2‐imino)stannylenoid

“…These values are significantly elongated in comparison to the reported adduct of 4-dimethylaminopyridinew ith (NIPr)SnN(SiMe 3 ) 2 (SnÀN imino = 2.0588(13) ), which represents an SnÀNs ingle bond. [14] Consequently,partial SnÀNdative bond character is ascribed to the tin-nitrogen interactions in 1,similar to the structurally related {(NIPr)SnN 3 } 2 which comprises ac yclic N 2 Sn 2 core (Sn À N = 2.194(3) a nd 2.178 (3) ). [14] Consequently,partial SnÀNdative bond character is ascribed to the tin-nitrogen interactions in 1,similar to the structurally related {(NIPr)SnN 3 } 2 which comprises ac yclic N 2 Sn 2 core (Sn À N = 2.194(3) a nd 2.178 (3) ).…”

“…[13] However,t he Sn À Na nd Li À Nb ond lengths in 1 and 5 differ only slightly and do not indicate that the structural deviation between the LiN 2 Sn cores (butterfly Figure 3. Hydrogen atoms are omitted for clarity.S elected bond lengths [] and bond angles [8 8]: Sn1ÀN1 2.183(6), Sn1ÀN4 2.194(6), Sn1ÀC55 2.15(3), Li1ÀN1 1.921(16), Li1À N4 1.920 (14), C1ÀN1 1.286(9), C1ÀN2 1.408(10), C1ÀN3 1.396(9), N4ÀC28 1.265(8), C28ÀN5 1.408(8), C28ÀN6 1.420(8);N1-Sn1-N4 81.1(3), N1-Li1-N4 95.5(6), Li1-N1-Sn19 1.1(4), Li1-N4-Sn190.8(5), N1-Sn1-C559 6.6(9), N4-Sn1-C559 6.4 (8). [13] Thermal ellipsoidsa re set at 40 %probability.Dip groups are depicted as stick models.…”

“…[11a] However, they are shorter than the Sn À N imino distance in three-coordinated benzobisstannylenes ( 2.2056-(14) , 2.206 (2) ) that mark an Sn À N imino dative bond. [14] Consequently,partial SnÀNdative bond character is ascribed to the tin-nitrogen interactions in 1,similar to the structurally related {(NIPr)SnN 3 } 2 which comprises ac yclic N 2 Sn 2 core (Sn À N = 2.194(3) a nd 2.178 (3) ). [11a] Notably,high dative bond character was attributed to the Sn À N imino interaction in stannyliumylidene VII and the respective bond length had been determined to be 2.197 (2) .…”

“…Its formation can be reasoned by oxidative addition of diiodine to the Sn II atom with subsequent extrusion of the chloro functionality to avoid an unfavorable high coordination number at the tin center. Hydrogen atoms are omitted for clarity.S elected bond lengths [] and bond angles [8 8]: Sn1ÀN1 2.143(5), Sn1ÀN4 2.179(4), Sn1ÀCl1 2.532(2), Li1ÀN1 2.004(9), Li1À N4 1.946(9), C1ÀN1 1.266 (6), C1ÀN2 1.409 (6), C1ÀN3 1.409 (6), N4À C28 1.263 (6), C28ÀN5 1.397 (7), C28ÀN6 1.410(6);N 1-Sn1-N4 80.68- (17), N1-Li1-N4 90.2(4), Li1-N1-Sn1 90.3(3), Li1-N4-Sn19 0.9(3), N1-Sn1-Cl1 87.29 (14), N4-Sn1-Cl18 7.75 (14). Synthesis of the bis(imino)stannylenoid 1.D ip = 2,6-diisopropylphenyl.…”

The role of the bis-trimethylsilylamido ligand, [N{SiMe3}2]−, in main group chemistry. Part 2: Structural chemistry of the metallic p-block elements

“…14) [115]. An attempt to synthesize benzo-bis(stannylenes), analogous to the -bis(germylenes), afforded instead the 1,4-benzoquinonediimines (141 and 142) due to oxidation of the1,2,4,5-tetra(alkylamine)benzene ligand [116].…”