Crystal structure of the dimeric bis(p-fluoro- and pentafluorophenylacetato)tetra-n-butyldistannoxanes

A Novel Macrocyclic Dimeric Dicarboxylato Distannoxane Assembled from a Flexible Dicarboxylic Acid

The novel macrocyclic complex [(Bu2Sn)2OL]2•CH3CN (2) has been prepared from the flexible dicarboxylic acid, LH2, (1). Single crystal X-ray diffraction shows that complex 2 has a centrosymmetric structure, with a central rhomboid cyclic Bu4Sn2O2 unit, linked at the oxygen atoms to two exocyclic tin atoms. The dicarboxylate ligands bridge exocylic and endocyclic tin atoms, completing two rings each of 22 atoms, and two of the four carbonyl oxygen atoms coordinate to the exocyclic tin atoms, to raise their coordination state to five and complete two more six-membered, rings.

Tetrakis(mu2-4-aminobenzoato)di-mu3-oxido-tetrakis[dibutyltin(IV)]

The molecule of the title compound, [Sn(4)(C(4)H(9))(8)(C(7)H(6)NO(2))(4)O(2)], lies about an inversion centre and is a tetranuclear bis(tetrabutyldicarboxylatodistannoxane) complex containing a planar Sn(4)O(2) core in which two mu(3)-oxide O atoms connect an Sn(2)O(2) ring to two exocyclic Sn atoms. Each Sn atom has a highly distorted octahedral coordination. In the molecule, the carboxylate groups of two aminobenzoate ligands bridge the central and exocyclic Sn atoms, while two further aminobenzoate ligands have highly asymmetric bidentate chelation to the exocyclic Sn atoms plus long O...Sn interactions with the central Sn atoms. Each Sn atom is also coordinated by two pendant n-butyl ligands, which extend roughly perpendicular to the plane of the Sn(4)O(10) core. Only one of the four unique hydrogen-bond donor sites is involved in a classic N-H...O hydrogen bond, and the resulting supramolecular hydrogen-bonded structure is an extended two-dimensional network which lies parallel to the (100) plane and consists of a checkerboard pattern of four-connected molecular cores acting as nodes. The amine groups not involved in the hydrogen-bonding interactions have significant N-H...pi interactions with neighbouring aminobenzene rings.

Insertion reaction of carbon dioxide into Sn–OR bond. Synthesis, structure and DFT calculations of di- and tetranuclear isopropylcarbonato tin(iv) complexes

The reaction of carbon dioxide with the stannane nBu2Sn(OiPr)2 and distannoxane [nBu2(iPrO)Sn]2O leads to the selective insertion into one Sn-OiPr bond generating the corresponding nBu2Sn(OiPr)(OCO2(i)Pr) and nBu2(iPrO)SnOSn(OCO2(i)Pr)nBu2 species. Both compounds are characterised by multinuclear NMR, FT-IR and single-crystal X-ray crystallography. In the solid state, they adopt a dimeric arrangement with bridging isopropoxy and terminal isopropylcarbonato ligands. The X-ray crystal structure of the dinuclear stannane shows that the Sn2O2 ring and the two Sn-OCO2C fragments are nearby coplanar. The same holds for the ladder-type tetranuclear distannoxane. The dimeric structures are also evidenced by solution NMR in non-coordinating solvents. Interestingly, the assignment of the exo and endo tin resonances of the dimeric distannoxane is unambiguous using a labeled 13CO2 experiment. The stability of the dimeric association has been probed in the stannane series on the basis of DFT calculations.