stituted cis,trans-cyclodeca-1,5-dienes (or cis,cis,trans-cyclodeca-1,4,7-trienes) [3]. These ten-membered cyclic compounds, like ( I ) , show no tendency to thermal polymerization such as that exhibited by cis,truns-cycloocta-1,5-diene [2] or cis,tuans-cyclonona-l,5-diene [4] ; instead, like ( I ) , they are converted by heat, via a four-center arrangement [5] to mono-or di-substituted cis-1,2-divinylcyclohexanes (or cis-
1,2-divinylcyclohexenes), e.g. ( 3 ) gives (Sa), while (4) gives (4a) and (4b). Unsubstituted (3) is converted to unsubstituted
biAcidic hydrolysis of phosphides, arsenides, nitrides, and germanides of magnesium and calcium yields phosphines, arsines, ammonia, and germane. Mixed hydrides are formed on hydrolysis of the corresponding solid solutions [l](magnesium phosphide/magnesium arsenide, magnesium phosphide/magnesium nitride, or magnesium arsenide/ magnesium nitride). Since the reaction has a radical mechanism, the formation of mixed hydrides of phosphorus, arsenic, nitrogen, and germanium also occurs in good yields even when compressed or tempered m i x t u r e s of the finely crystalline salts are hydrolysed. The phosphides, arsenides, and germanides of calcium and magnesium were obtained from magnesium powder 199.85 % purity from Messrs. Schuchardt, Munchen (Germany)] or