# Diorganotin(IV) Complexes of Organoselenolato Ligands with Pyrazole Moieties—Synthesis, Structure and Properties

## TL;DR

This paper describes the synthesis and structural analysis of diorganotin(IV) complexes with organoselenolato ligands containing pyrazole moieties.

## Contribution

The study introduces new diorganotin(IV) complexes and reveals their structural behavior in solution and solid state.

## Key findings

- NMR spectra confirmed the presence of Se–Sn bonds in solution.
- Compounds 4 and 5 formed selenium-bridged dimeric species in chlorinated solvents.
- Solid-state structures showed N→Sn intramolecular coordination in some compounds.

## Abstract

Diorganotin(IV) compounds of types RR′Sn(SeCH2CH2pz)2 [R = R′ = nBu (2), Ph (3); R = 2-(Me2NCH2)C6H4, R′ = Me (4), nBu (5), Ph (6)], and RR′SnX(SeCH2CH2pz) [R = 2-(Me2NCH2)C6H4, R′ = nBu, X = Cl (7), R′ = Me, X = SCN (9)], as well as [2-(Me2NCH2)C6H4](Me)Sn(NCS)2 (8), and the tin(II) Sn(SeCH2CH2pz)2 (10) (pz = pyrazole), were prepared by salt metathesis reactions between the appropriate diorganotin(IV) dichloride or dipseudohalide and Na[SeCH2CH2pz], with the latter freshly prepared from (pzCH2CH2)2Se2 (1). The solution behaviour of these compounds was investigated by multinuclear NMR (1H, 13C, 77Se, 119Sn), and the NMR spectra showed the existence of the Se–Sn bonds in solution. Compounds 4 and 5 showed decomposition in a solution of chlorinated solvents with the formation of selenium bridged dimeric species of type {[2-(Me2NCH2)C6H4](R’)Se}2 [R′ = Me (4-a), nBu (5-a)], as the single-crystal X-ray diffraction studies revealed, in contrast with compound 9, for which a monomeric structure was observed with the desired composition. The solid state structures of 4-a, 5-a, 8, and 9 revealed N→Sn intramolecular coordination of the nitrogen atom in the pendant CH2NMe2 arm. The NMR spectra suggested such a coordination at room temperature only for compound 7.