Octabutyl-1k2C,2k2C,3k2C,4k2C-di-µ3-oxo-1:2:3k3O;2:3:4k2O-di-µ2-phenoxy-1:2k2O;3:4k2O-diphenyoxy-1kO,4kO-tetratin(IV)

The dimeric title compound, tetrabutyldiphenoxydistannoxane, [Sn₄(C₄H₉)₈(C₆H₅O)₄O₂], adopts a ladder-type structure, featuring an almost planar inorganic framework with three four-membered Sn₂O₂ rings and four coplanar phenoxy groups.

A dimeric tellurastannoxane carbonate cluster, tetra-tert-butyl-di-µ3-carbonato-tetrakis-[4-(N,N-dimethylamino)phenyl]di-µ-oxo-ditelluriumditin chloroform tetrasolvate

The title compound, [Sn₂Te₂(C₄H₉)₄(CO₃)₂O₂(C₈H₁₀N)₄]·4CHCl₃ or [(p-Me₂NC₆H₄)₂TeOSn^tBu₂CO₃]₂·4CHCl₃, contains an almost planar centrosymmetric inorganic Sn₂Te₂O₈C₂ core and hypercoordinated Sn and Te atoms. The structure features four secondary intramolecular Te...O contacts.

Soluble poly-3-alkylpyrrole polymers on films and fabrics

Conductive textiles with specific properties can be produced by the chemical polymerisation of a range of 3-alkylpyrroles in the presence of textiles. The morphologies of these coatings are altered from the traditional conductive coatings. Comparison using a SEM reveals substantial differences.

Synthesis and structure of bis(para-methoxyphenyl)selenoxide and its monohydrate. theoretical considerations of the hydration of diorganoselenium oxides

The title compound was prepared by base hydrolysis of (p-MeOC₆H₄)₂SeCl₂ in water and isolated as the crystalline monohydrate, (p-MeOC₆H₄)₂SeO·H₂O, in which the water molecule is associated via hydrogen-bonding. Water-free (p-MeOC₆H₄)₂SeO was obtained crystalline after drying and recrystallisation from toluene. Both crystal phases were investigated by single crystal X-ray diffraction. Preliminary DFT calculations at the B3LYP/LANL2DZdp level of theory suggest that the hydrogen bonded complexes R₂SeO·H₂O (R = H, Me, Ph) are by 2.79, 3.36 and 11.10 kcal mol^-1 more stable than the corresponding elusive diorganoselenium dihydroxides R₂Se(OH)₂. The hydrogen bond energies of R₂SeO·H₂O (R = H, Me, Ph) are 5.98, 7.18 and 5.89 kcal mol^-1.

Incorporation of group 14 elements into siloxane-bridged paracyclophanes cyclo-[p,p´-Me2SiC6H4EMe2C6H4SiMe2O]2 (E = C, Si, Ge, Sn)§

The bis(arylene silanes) p,p'-HMe₂SiC₆H₄EMe₂C₆H₄SiMe₂H (E = C (10), Si (11), Ge (12), Sn(13)) were prepared by the in situ Grignard reaction of p,p'-BrC₆H₄CMe₂C₆H₄Br, Mg turnings, and HSiMe₂Cl (for 10) and the Grignard reaction using p-HMe₂SiC₆H₄Br, Mg turnings, and Me₂ECl₂ (E = Si for 11, Ge for 12, Sn for 13). The oxidation of 10-13 using Pearlman's catalyst, Pd(OH)₂/C, in aqueous THF provided the bis(arylene silanols) p,p'-HOMe₂SiC₆H₄EMe₂C₆H₄SiMe₂OH (E = C (14), Si (15), Ge (16), Sn(17)). The HCl-catalyzed condensation of 14-17 in highly diluted solutions of acetone/water afforded the siloxane-bridged paracyclophanes cyclo-[p,p'-Me₂SiC₆H₄EMe₂C₆H₄SiMe₂O]₂ (6-9) that incorporate the group 14 elements E = C, Si, Ge, and Sn. Compounds 6-17 were investigated by multinuclear solution and solid-state NMR spectroscopy and 6 and 9 also by X-ray crystallography.

Understanding ring strain and ring flexibility in six - and eight-membered cyclic organometallic group 14 oxides

A simple model was developed for the approximation of ring strain energies of homo- and heterometallic, six- and eight-membered cyclic organometallic group 14 oxides and the degree of puckering of their ring conformations. The conformational energy of a ring is modelled as the sum of its angular strain components. The bending potential energy functions for the various endocyclic M–O–M′ and O–M–O linkages (M, M′=Si, Ge, Sn) were calculated at the B3LYP/(v)TZ level of theory using H3MOM′H3 and H2M(OH)2 as model compounds. For the six-membered rings, the minimum total angular contribution to ring strain, ERSGmin was calculated to decrease in the order: cyclo-(H2SiO)3 (13.0 kJ mol−1)>cyclo-H2Sn(OSiH2)2O (7.0 kJ mol−1)>cyclo-H2Ge(OSiH2)2O (4.9 kJ mol−1)>cyclo-H2Si(OSnH2)2O (3.4 kJ mol−1)>cyclo-(H2SnO)3 (1.7 kJ mol−1)>cyclo-H2Si(OGeH2)2O (0.8 kJ mol−1)≈cyclo-H2Ge(OSnH2)2O (0.7 kJ mol−1)>cyclo-H2Sn(OGeH2)2O (0.1 kJ mol−1)≈cyclo-(H2GeO)3 (0 kJ mol−1). All of the six-membered rings were predicted to adopt (nearly) planar conformations (a=0.996<a<1). By contrast, all eight-membered rings were predicted to adopt strainless, but puckered conformations. The degree of puckering was predicted to increase in the order: cyclo-(H2SiO)4 (a=0.983)<cyclo-H2Sn(OSiH2O)2SiH2 (a=0.959)<cyclo-(H2SiO)2(H2SnO)2 (a=0.942)< cyclo-H2Si(OSnH2O)2SiH2 (a=0.935)<cyclo-(H2SnO)4 (a=0.916)<cyclo-(H2GeO)4 (a=0.885). The differences in ring strain and the degree of puckering were linked to the different electronegativities of Si, Ge and Sn. The results obtained are consistent with experimental ring strain energies; reactivities towards ring opening polymerizations or ring expansion reactions and observed ring conformations of cyclic organometallic group 14 oxides.

The origin of ring strain and conformational flexibility in Tri- and Tetrasiloxane Rings and their heavier group 14 congeners

Never change a winning team. Since the appearance of the first volume in 1994 this series has become a well respected forum, and like its highly successful predecessors, this sixth volume again brings together leading experts from academia and industry to provide a comprehensive and critical survey of the frontiers of current industrial and university research. - Synthesis and characterization of new organosilicon compounds - Applications in polymer and materials science - Summary of the latest research results The result is a unique compendium with two volumes of first-hand information, vital for all experts working in this field.

Comparison of the flexibility of eight-membered tetrasiloxane and stannasiloxane rings: a crystallographic and computational study

The syntheses and crystal structures of the eight-membered cyclo-stannasiloxanes cyclo-[t-Bu(OH)Si(OSnt-Bu₂O)₂Si(OH)t-Bu] (1) and cyclo-{t-Bu₂Si[OSn(CH₂SiMe₃)₂O]₂Sit-Bu₂} (2) as well as the synthesis of the six-membered cyclo-stannasiloxane cyclo-{t-Bu₂Si[OSn(CH₂SiMe₃)₂]₂O} (3) are reported. Compound 1 crystallizes as its trans isomer, but the cis isomer dominates in solution. In agreement with the experimentally obtained results, ab initio and DFT calculations on the model compounds cyclo-(H₂SiO)₄ (4), cyclo-[H₂Si(OSnH₂)OSiH₂] (5), cyclo-O(H₂SiOSnH₂)₂O (6), and cyclo-[H₂Si(OSiH₂)OSnH₂] (7) indicate that the energetic preference to adopt puckered structures increases and the ring flexibility decreases with an increasing number of tin atoms in the ring. The rich diversity of puckered conformations is attributed to the steric demand of the different organic substituents.

New insights in asymmetric tetraorganodistannoxane ladder formation. A NMR-spectroscopic and crystallographic study

The syntheses of the asymmetrically substituted tetraorganodistannoxanes [t-Bu₂(X)SnOSn(Y)(CH₂SiMe₃)₂1₂ (1, X = Y = OH; 2, X = Cl, Y = OH; 3, X = Y = Cl) are reported and their structures in solution and in the solid state are characterized by multinuclear NMR spectroscopy and single crystal X-ray analyses. In toluene, the tetrahydroxy-substituted derivative 1 is in equilibrium with the organotin oxides cyclo-[t-Bu₂Sn{OSn(CH₂SiMe₃)₂}₂O] (4), cyclo[(Me₃SiCH₂)₂Sn(OSnt-Bu₂)₂O] (5), and cyclo-(t-Bu₂SnO)₃, and some additional, undefined species containing pentacoordinated tin atoms. In contrast, the dihydroxydichloro-substituted derivative 2 is inert in solution.

Hydrolysis of bis((trimethylsilyl)methyl)tin dihalides. Crystallographic and spectroscopic study of the hydrolysis pathway

The synthesis and characterization by multinuclear NMR spectroscopy of the diorganotin dihalides (Me₃SiCH₂)₂SnX₂ (1, X = Cl; 2, X = Br), the diorganotin dichloride water adduct (Me₃SiCH₂)₂SnCl₂·H₂O (1a), the dimeric tetraorganodistannoxanes [(Me₃SiCH₂)₂(X)SnOSn(Y)(CH₂SiMe₃)₂]₂ (3, X = Y = Cl; 4, X = Br, Y = OH; 5, X = Br, Y = F; 6, X = Y = OH; 8, X = Cl, Y = OH), and the molecular diorganotin oxide cyclo-[(Me₃SiCH₂)₂SnO]₃ (7) are reported. The structures in the solid state of compounds 1a, 3, 6, and 7 were determined by single-crystal X-ray analysis. In toluene solution, the hydroxy-substituted tetraorganodistannoxane 6 is in equilibrium with the diorganotin oxide 7 and water. The eight-membered diorganotin oxide cyclo-[(Me₃SiCH₂)₂SnO]₄ (7a) is proposed to be involved in this equilibrium. On the basis of the results of this and previous works, a general hydrolysis pathway is developed for diorganotin dichlorides containing reasonably bulky substituents.

Synthesis and reactivity of para-substituted benzoylmethyltellurium(II and IV) compounds: observation of intermolecular C-H-O hydrogen bonding in the crystal structure of (p-MeOC6H4COCH2)2TeBr2

Bis(p-substituted benzoylmethyl)tellurium dibromides, (p-YC₆H₄COCH₂)₂TeBr₂, (y=H (1a), Me (1b), MeO (1c)) can be prepared
either by direct insertion of elemental Te across CRf-Br bonds (where C_Rf refers to α-carbon of a functionalized organic moiety) or by the oxidative addition of bromine to (p-YC₆H₄COCH₂)₂Te (y = H (2a), Me (2b), MeO (2c)). Bis(p-substituted benzoylmethyl)tellurium dichlorides, (p-YC₆H₄COCH₂)₂TeCh (y = H (3a), Me (3b), MeO (3c)), are prepared by the reaction of the bis(p-substituted benzoylmethyl)tellurides 2a--c with S0₂Cl₂, whereas the corresponding diiodides (p-YC₆H₄COCH₂)₂Teh (y = H
(4a), Me (4b), MeO (4c)) can be obtained by the metathetical reaction of la--c with KI, or alternatively, by the oxidative addition of
iodine to 2a--c. The reaction of 2a--c with allyl bromide affords the diorganotellurium dibrornides la--c, rather than the expected
triorganotelluronium bromides. Compounds 1-4 were characterized by elemental analyses, IR spectroscopy, ¹H, ^l3C and ¹²⁵Te
NMR spectroscopy (solution and solid-state) and in case of Ie also by X-ray crystallography. (p-MeOC₆H₄COCH₂)₂TeBr₂ (1c) provides, a rare example, among organotellurium compounds, of a supramolecular architecture, where C-H-O hydrogen bonds appear to be the non-covalent intermolecular associative force that dominates the crystal packing.