Electrochemical and Reactivity Studies of N→Sn Coordinated Distannynes

Synthesis and Reactivity of an Iron-Tin Complex with Adjacent Stannylidyne and Ferriostannylene Units

Heavier transition metal carbyne analogs hold significant potential for cooperative activation of small molecules. However, complexes containing more than one heavier tetrylidyne ligand RE (E = Si, Ge, Sn, Pb) are rare due to the high oligomerization tendency of RE ligands. In this study, we describe the complex [Fe(SnAr')2] (1; Ar' = 2,6-Dipp2-C6H3, Dipp = 2,6-iPr2-C6H3), which features adjacent Fe-Sn single and double bonds. Complex 1 exhibits versatile reactivity with transition metal and main group compounds. Treatment of complex 1 with Ni(COD)2 (COD = 1,5-cyclooctadiene) yields the tetranuclear complex [Fe(μ-SnAr')2Ni] (2), characterized by an unusual "push-pull" interaction between nickel(0) and the two coordinating Sn atoms, as revealed by quantum chemical studies. The reaction of complex 1 with AlBr3 results in Al-Br bond cleavage and Ar' migration to aluminum. CH3I adds oxidatively to the Sn atom that is singly bonded to Fe, while PMe3 coordinates to Fe, inducing reversible cleavage of the Fe═Sn double bond. In addition, complex 1 activates inorganic molecules. CO2 undergoes disproportionation to produce a carbonate-bridged Ar'Sn(μ-OCO2)SnAr' ligand, whereas CS2 is reductively coupled to form an ethylene tetrathiolate ligand ([C2S4]4-). The reaction with white phosphorus (P4) generates an unusual Ar'P4Sn2Ar' ligand. This multifaceted reactivity illustrates the behavior of the Fe and Sn sites in complex 1, suggesting that complexes of this type are promising reagents for small molecule activation.

One-Electron (2c/1e) Tin···Tin Bond Stabilized by ortho-Phenylenediamido Ligands

Odd-electron bonds, i.e., the two-center, three-electron (2c/3e), or one-electron (2c/1e) bonds, have attracted tremendous interest owing to their novel bonding nature and radical properties. Herein, complex [K(THF)6][LSn:···Sn:L] (1), featuring the first and unsupported 2c/1e Sn···Sn σ-bond with a long distance (3.2155(9) Å), was synthesized by reduction of stannylene [LSn:] (L = N,N-dpp-o-phenylene diamide) with KC8. The one-electron Sn-Sn bond in 1 was confirmed by the crystal structure, DFT calculations, EPR spectroscopy, and reactivity studies. This compound can be viewed as a stabilized radical by delocalizing to two metal centers and can readily mediate radical reactions such as C-C coupling of benzaldehyde.

Coordination of a Central Atom by Multiple Intramolecular Pnicogen Bonds

A central pnicogen Z atom (Z = Sb, As) is covalently attached to the O atom of three -O(CH₂)_nX chains where X represents either an aldehyde or amine group. The chain can fold around so that the basic X group can engage in a noncovalent pnicogen bond with the central Z. The formation of up to three pnicogen bonds is energetically favored. The amine appears to engage in stronger pnicogen bonds than does the aldehyde, and bonds to Sb are favored over As, but there is little dependence on the length of the chain. The formation of each successive pnicogen bond reduces the magnitude of the σ-holes surrounding the Z atom, which tends to weaken the attraction for the basic end of the chain.

Linear, mixed-valent homocatenated tri-tin complexes featuring Sn-Sn bonds

A series of tri-tin complexes (LPhSn)3X with triple-decker structures (LPh = 2,5-di(o-pyridyl)-3,4-diphenylpyrrolate; X = Cl, AlCl4, OTf, and PF6) was synthesized by reducing LPhSnCl with LiBsBu3H and subsequent reactions. Structural characterization of (LPhSn)3Cl revealed a Sn-Sn-Sn core, and DFT calculations suggest that its HOMO is primarily σ-bonding along the tri-tin framework. (LPhSn)3Cl reacts with W(CO)5THF to afford (LPhSn)2(W(CO)5)2 and LPhSnCl, implying that (LPhSn)3Cl may exhibit dynamic behavior in solution.

Investigating the structural chemistry of organotin(IV) compounds: recent advances

Organotin(IV) compounds have been considered for their outstanding industrial, medical and specific applications in the synthesis of various types of chemical compounds. In this review, we have focused on the structural chemistry of organotin(IV) compounds, including coordination chemistry, the effect of structure on reactions, bond formations from the perspective of structure and investigation of the structure of organotin(IV) compounds in different phases. The structural chemistry of organotin(IV) compounds is subject to interest due to their major impact on predicting the properties and drumming up support for pushing back the frontiers of synthesis of organotin(IV) compounds with advanced properties.