Synthesis and Structure of a Heptacoordinate Trichlorostannane Bearing a Triarylmethyl-Type Tetradentate Ligand

Abstract

Trichloro[tris(3-tert-butyl-6-methoxyphenyl)methyl]-stannane (1), containing a tetradentate ligand with three methoxy groups as coordinating sites, was synthesized by the reaction of the corresponding (triarylmethyl)lithium species with tin tetrachloride. In contrast to the cases of the previously reported silicon and germanium analogues, 1 decomposed during column chromatography on silica gel and was slightly unstable against moisture. X-ray crystallographic analysis of 1 showed a heptacoordinate structure with interatomic distances between the oxygen atom and the central tin atom shorter than the sum of van der Waals radii.

Metal Complexes Bearing Dianionic Trityl/Aryloxide Ligands: Rational Synthesis, Structural Diversity, and Redox Properties

“…The widest bond angle around Sn(1) is C(7)–Sn(1)–C(34) (144.95(11)°), possibly as a result of the steric repulsion between two triarylmethyl groups. The Sn–C bond lengths in 5a (Sn(1)–C(7) 2.182(3) Å, Sn(1)–C(34) 2.180(3) Å) are much shorter in comparison with those observed for trichloro[tris(3‐ tert ‐butyl‐6‐methoxyphenyl)methyl]stannane (2.215(3) Å), (tris(2,6‐dimethoxyphenyl)methyl)tin trihalides (2.22(1) to 2.312(5) Å) and a series of tris(9‐triptycyl)stannane derivatives (2.289(9) to 2.329(5) Å) . The central carbon atoms of triarylmethyl carbanions in 5a are sp 3 hybridized and display pyramidalized geometry (sums of intraligand bond angles equal to 341.3° (C(7)) and 340.5° (C(34))), similar to the case of zinc complexes 4a and 4b .…”

Can One σ*-Antibonding Orbital Interact with Six Electrons of Lewis Bases? Analysis of a Multiply Interacting σ* Orbital

“…In addition, heptacoordinate silane, germane, and stannane compounds with different types of chelating ligands, such as tetradentate XL 3 -type ligands (type II in Scheme ), have been reported. In this structure, the L→E dative bonds are formed at the position trans to the three E–X covalent bonds. − In this case also, one lone pair orbital interacts with one σ*-antibonding orbital of the E–X bond in this type II compound.…”

“…In general, one donor orbital interacts with one acceptor orbital to form one donor–acceptor bond. Compounds of heavier group 14 elements described as EX 4 (E = Si, Ge, Sn) are known to serve as Lewis acids because its σ*(E–X) orbital can interact with a lone pair of Lewis bases. − In such a compound, one σ*(E–X) orbital interacts with one lone pair of L to form one L→E dative bond, as mentioned above. For instance, silane and germane compounds containing three bidentate LX-type ligands have a heptacoordinate structure, as shown in type I in Scheme .…”

Synthesis and Characterization of ortho‐Thio‐Functionalized Triarylmethyl Palladium Complexes

“…For the main group elements 3–5, heptacoordinated metal complexes (M = Si, Sn, Ge)11 and complexes for which triarylmethyl = triptycenyl have been described; they are kinetically stabilized by the bulky substituent 12,13. Early (M = Ti, Zr, Nb)14,15 as well as late (M = Ir, Pt)16,17 transition‐metal complexes are known.…”