Robert Wilfred Matthews Wardle

Structure of bis(tetraphenylphosphonium) pentaselenide

P(C6Hs)4)2(Ses), Mr= 1073.6, monoclinic, P2~ (C2), a=9.573 (7), b= 16.945 (12), c= 13.563(10)A, fl=105.29(2) ° , V=2122(3)A 3, z = 2, D x = 1.68 g cm -3, Mo Ko., 2(Kay) = 0.7093 A, /z= 43.8 cm -~, F(000)= 1054.6 including anomalous dispersion, T= 123K, R(F 2)=0.075 for 3681 reflections. The Se 2- chain has a trans con- formation with short terminal and long internal Se-Se bonds of average lengths 2.315 (2) and 2.361 (2)A, respectively. The internal and the average terminal Se-Se-Se angles are 110.59 (7) and 108.93 (6) °, respectively. The Se(1) and Se(5)atoms are twisted out of the Se(2), Se(3), Se(4) plane by torsion angles of 77.32 (8) and 89.16 (7) ° , respectively. Introduction. Soluble salts of transition-metal selenium anions (MxS%) 2- are rare. We recently showed that selenation of ammonium metavanadate with bis(di- methyloctylsilyl) selenide produced the V2Se23 ion (Chau, Wardle & Ibers, 1987). As a continuation of our efforts to discover new transition-metal selenium anions we have investigated the reaction of zirconium tetra- ethoxide with bis(dimethyloctylsilyl) selenide. In an attempt to crystallize the resulting product, we obtained the title compound, presumably as a result of air- oxidation of a zirconium selenide anion. Here, we report its molecular structure and compare it with that of other Se 2- anions. Experimental. Dark-brown crystals of the title com- pound were obtained by slow diffusion of ether into a DMF solution of the product that resulted from the selenation of zirconium tetraethoxide by bis(dimethyl- octylsilyl) se|enide. The red powdery product was prepared by combining 0.1 g zirconium, 0.5 g zir- conium tetraethoxide, 0.2 g selenium, and 0.9 g tetra- phenylphosphonium chloride in 25 mL DMF with 1.5 g bis(dimethyloctylsilyl) selenide. After stirring overnight at room temperature the dark red-brown solution was filtered. Addition of ether caused the precipitation of the red powder; it was filtered, washed twice with ether, and suction dried. This material has an infrared absorption at 270 cm-L When the material was recrystallized to give the title compound this absorption peak dis- appeared, possibly because of decomposition. A very

Effect of diesel injector tip deposits on transient spray behavior

The structural characteristics of high pressure diesel sprays have been investigated using two different complementary techniques, and the impact of injector fouling on the spray development has been assessed. In the first novel technique, fuel was injected into a reservoir of water, a liquid that offered high density ambient conditions. In a second technique, fuel was injected into a pressurised constant volume chamber.