The gas-phase structure and some reactions of the bulky primary silane (Me(3)Si)(3)CSiH(3) and the solid-state structure of the bulky dialkyl disilane [(Me(3)Si)(3)CSiH(2)](2).

The molecular structure of the bulky primary silane, (Me(3)Si)(3)CSiH(3), in the gas phase has been determined by electron diffraction. Photolysis of (Me(3)Si)(3)CSiH(3) affords a convenient route to the bulky dialkyl disilane, [(Me(3)Si)(3)CSiH(2)](2), which is the first 1,2-dialkyldisilane to be structurally characterised by single-crystal X-ray diffraction. The disilane has an unusually large Si-Si-C angle of 120.

trans-Bis(1,1,1,5,5,5-hexa-fluoro-pentane-2,4-dionato-κO,O')bis-(4-methyl-1,2,3-selenadiazole-κN)copper(II).

In the title compound, [Cu(C(5)HF(6)O(2))(2)(C(3)H(4)N(2)Se)(2)], the Cu(II) atom (site symmetry ) is coordinated by two O,O'-bidentate 1,1,1,5,5,5-hexa-fluoro-2,4-penta-nedione (hp) ligands and two 4-methyl-1,2,3-selenadiazole mol-ecules, resulting in a slightly distorted trans-CuN(2)O(4) octa-hedral geometry in which the cis angles deviate by less than 3° from 90°. The selenadiazole plane is canted at 73.13 (17)° to the square plane defined by the penta-nedionate O atoms.