The photophysical properties of naphthalene bridged disilanes.

Structural isomers of naphthalene-bridged disilanes were prepared via catalytic intramolecular dehydrocoupling of disilyl precursors using Wilkinson's catalyst. Interestingly, it was observed that interchanging the side groups on the silicon atoms altered the photophysical properties of the bridged disilanes. Herein, we report the first example of naphthalene bridged disilanes forming excimers in non-polar solvents. Cyclic voltammetry experiments and DFT calculations were performed to analyse the band gaps of the compounds and σ-π mixing in the bridged disilanes.

Catalytic Synthesis of Oligosiloxanes Mediated by an Air Stable Catalyst, (C6F5)3B(OH2).

The utility of (C6F5)3B(OH2) as catalyst for the simple and environmentally benign synthesis of oligosiloxanes directly from hydrosilanes, is reported. This protocol offers several advantages compared to other methods of synthesizing siloxanes, such as mild reaction conditions, low catalyst loading, and a short reaction time with high yields and purity. The considerable H2O-tolerance of (C6F5)3B(OH2) promoted a catalytic route to disiloxanes which showed >99% conversion of three tertiary silanes, Et3SiH, PhMe2SiH, and Ph3SiH. Preliminary data on the synthesis of unsymmetrical disiloxanes (Si-O-Si') suggests that by modifying the reaction conditions and/or using a 1:1 combination of silane to silanol the cross-product can be favored. Intramolecular reactions of disilyl compounds with catalytic (C6F5)3B(OH2) led to the formation of novel bridged siloxanes, containing a Si-O-Si linkage within a cyclic structure, as the major product. Moreover, the reaction conditions enabled recovery and recycling of the catalyst. The catalyst was re-used 5 times and demonstrated excellent conversion for each substrate at 1.0 mol% catalyst loading. This seemingly simple reaction has a rather complicated mechanism. With the hydrosilane (R3SiH) as the sole starting material, the fate of the reaction largely depends on the creation of silanol (R3SiOH) from R3SiH as these two undergo dehydrocoupling to yield a disiloxane product. Generation of the silanol is based on a modified Piers-Rubinsztajn reaction. Once the silanol has been produced, the mechanism involves a series of competitive reactions with multiple catalytically relevant species involving water, silane, and silanol interacting with the Lewis acid and the favored reaction cycle depends on the concentration of various species in solution.

Structural analysis of 2-iodo-benzamide and 2-iodo-N-phenyl-benzamide.

The title compounds, 2-iodo-benzamide, C7H6INO (I), and 2-iodo-N-phenyl-benzamide, C13H10INO (II), were both synthesized from 2-iodo-benzoic acid. In the crystal structure of (I), N-H⋯O and hydrogen bonds form two sets of closed rings, generating dimers and tetra-mers. These combine with C-I⋯π(ring) halogen bonds to form sheets of mol-ecules in the bc plane. For (II), N-H⋯O hydrogen bonds form chains along the a-axis direction, while inversion-related C-I⋯π(ring) contacts supported by C-H⋯π(ring) interactions generate sheets of mol-ecules along the ab diagonal.