Selvarajan Nagendran

Organotin assemblies containing SnO bonds

Abstract This review deals with the recent progress in the area of organotin assemblies that contain Snue5f8O bonds. Various kinds of tri-, di- and monoorganotin compounds are described in terms of their preparation by methods such as hydrolysis of organotin halides, reactions of suitable oragnotin compounds with various kinds of substrates such as carboxylic acids, sulfonic acids, oxide transfer reagents etc. The structural characterization of these compounds by the use of 119 Sn-NMR, 119 Sn Mossbauer and X-ray crystallography is presented in considerable detail. The amazing structural diversity present in this family of compounds is discussed.

Phosphazenes as scaffolds for the construction of multi-site coordination ligands

Chlorocyclophosphazenes containing a reactive periphery and a robust framework offer an ideal platform for the construction of a large variety of multi-site coordination ligands. Various types of neutral or (multi)anionic multi-site coordinating ligands can be assembled containing different numbers, type and stereochemical orientations of coordination sites reflecting the ease of modulation of these ligand types. Also it is possible to construct new types of macrocyclic ligands using cyclophosphazenes as scaffolds. The interaction of these ligands with transition and main group metals leads to a number of different complex types showing the rich diversity that is present in this family of compounds. A study of these ligands in principle also allows the assembly of the corresponding polymeric ligands.

Tridentate N3 capping coordination behaviour of potentially multi-site coordinating cyclotriphosphazenes: synthesis and spectroscopic studies of 2,2-spiro(1,3-propanediamino)-4,4,6,6-tetrakis(3,5-dimethylpyrazolyl)cyclotriphosphazene, 2,2-diamino-4,4,6,6-tetrakis(3,5-dimethylpyrazolyl)-cyclotriphosphazene and their mononuclear complexes; X-ray structure of ATPCTP·CoCl2

Abstract Two new potentially multi-site coordinating cyclophosphazenes, gem-N3P3[HN(CH2)3NH](3,5-Me2Pz)4 (STPCTP) and gem-N3P3(NH2)2(3,5-Me2Pz)4 (ATPCTP) have been synthesised and characterised. These form mononuclear complexes with Cu(II), Co(II) and Ni(II) halides which have been studied by optical spectroscopy. An X-ray analysis of ATPCTP·CoCl2 shows the Co(II) atom to exist in a distorted trigonal bipyramidal geometry in which the two chloride atoms and a nitrogen atom of the cyclophosphazene ring form the equatorial plane; the axial positions are occupied by nitrogen atoms derived from the two non-geminal pyrazolyl substituents. The amino substituents on the cyclophosphazene ring do not take part in coordination.

Cycloalkylaminocyclo- and Polyphosphazenes: X-ray Crystal Structures of gem-Tetrakis(cyclohexylamino)dichlorocyclotriphosphazene and Octakis(cyclopropylamino)cyclotetraphosphazene

The reactions of chlorocyclophosphazenes N3P3Cl6 (1) and N4P4Cl8 (2) and polydichlorophosphazene (3) with cyclohexylamine, cyclopentylamine, and cyclopropylamine have been studied. The major product with 1 is the geminal tetrakis derivative N3P3Cl2(NHR)4, while 2 gives the completely substituted derivative, N4P4(NHR)8. X-ray crystal structure determinations of N3P3Cl2(NHC6H11)4 (1a) and N4P4(NHC3H5)8 (2c) have been carried out. 1a crystallizes in a triclinic space group, P1, with a = 11.2330(13) A, b = 11.4269(16) A, c = 13.4055(12) A, α = 72.211(10)°, β = 72.150(9)°, γ = 81.777(11)°, V = 1557.3(3) A3, and Z = 2. 2c crystallizes in a monclinic space group, P21/n, with a = 12.433(3) A, b = 20.484(4) A, c = 12.645(3) A, β = 92.81(2)°, V = 1557.3(3) A3, and Z = 4. The cycloalkylamino-substituted polyphosphazenes contain a small amount of residual chlorine atoms. These have high glass transition temperatures.

New approach for the assembly of a multi-site coordinating polymeric ligand: Synthesis of a pendant pyrazolyl cyclotriphosphazene containing polymer

Abstract A new mult-site coordinating polymeric ligand, 6 , containing a pendant cyclotriphosphazene moiety has been synthesised in high yield by a simple synthetic procedure

Si-O and P-O motifs in inorganic rings and clusters

This article presents a brief overview of different kinds of silanols and the important reactions of N-bonded silanetriols. The synthesis and characterization of silanediols containing Si-N and Si-C bonds, (2,4,6-Me3C6H2)N(SiMe3)Si(Me)(OH)2 (1e) is described. 1e shows a polymeric crinkled tape type of structure due to extensive intermolecular hydrogen bonding. We also describe the formation of a neutral copper(II) complex derived from the reaction of CuCl2 with (O)P(3,5-Me2Pz)3 where the ligand undergoes a facile P-N bond cleavage and functions as an N2O type of tridentate ligand.

ORGANOSTANNOXANE MOTIFS IN CAGES AND SUPRAMOLECULAR ARCHITECTURES

The reactions of n-butyl stannonic acid with(PhO) 2 P(O)H leads to the formation of a hexameric tin cage [{(n-BuSn) 3 (PhO) 3 O} 2 {HPO 3 } 4 ].This reaction involves an in situ P─O bond cleavage and the generation of a [HPO 3 ] 2− ion. A direct reaction of six equivalents of n-BuSnO(OH) acid with six equivalents of C 6 H 5 OH and four equivalents of H 3 PO 3 also leads to the formation of same cage structure. A tetranuclear organooxotin cage[(PhCH 2 ) 2 Sn 2 O(O 2 P(OH)-t-Bu) 4 ] 2 has been assembled by debenzylation involving the reaction of (PhCH 2 ) 2 SnCl 2 ,(PhCH 2 ) 2 SnO·H 2 O or (PhCH 2 ) 3 SnCl with two equivalents of t-BuP(O)OH 2 . A half-cage intermediate [(PhCH 2 ) 2 Sn 2 O(O 2 P(OH)-t-Bu) 4 ] has been detected. New organotin cations of the type [n-Bu 2 Sn(H 2 O) 4 ] 2+[2,5-Me 2 -C 6 H 3 SO 3 ]− 2 and {[n-Bu 2 Sn(H 2 O) 3 LSn(H 2 O) 3 (n-Bu) 2 ] 2+[1,5-(SO 3 ) 2 -C 10 H 6 ] 2−} have been obtained in the reactions of n-Bu 2 SnO or (n-Bu 3 Sn) 3 O with 2,5-dimethyl sulfonic acid and 1,5-naphthalene disulfonic acid respectively. These organotin cations form interesting supramolecular structures in the solid state as a result of O─H─···O hydrogen bonding.

First characterisation of weak hydrogen bonds in organoantimony compounds: C–H⋯Cl–Sb-mediated, zig-zag, supramolecular polymeric architecture in [Ph2Sb(Cl){S2C2(CN)2}]

The design and solid-state structure of an organoantimony compound containing several weak secondary interactions is described.

Hypervalent tris(catecholato)silicate derived from rice husk ash

Abstract Rice husk ash with a particle size distribution between 2 and 7 μm reacts with catechol and sodium methoxide in methanol to afford the tris(catecholato)silicate, Na2[Si(o-C6H4O2)3] 1.

First example of a Sn–C bond cleaved product in the reaction of Ph3SnOSnPh3 with carboxylic acids. 3D-Supramolecular network formation in the X-ray crystal structure of [Ph2Sn(OH)OC(O)(Rf)]2, Rf= 2,4,6-(CF3)3C6H2

A 1:2 reaction of Ph3SnOSnPh3 1 with RfCOOH 2 leads to the formation of [Ph2Sn(OH)OC(O)(Rf)]2 3, by means of a facile Sn-C bond cleavage process.