REACTION OF ISOTHIOCYANATES AND ISONITRIL ES WITH R(2)AL-ALR(2) [R=CH(SIME(3))(2)] - SINGLE AND DOUBLE INSERTION OF ISONITRILE INTO THE AL-AL BOND

Tetrakis[bis(trimethylsilyl)methyl]dialuminium(4) 1 reacts with phenyl or tert-butyl isothiocyanate with cleavage of the C=S double bond. Tw o compounds are formed: R(2)Al-S-AlR(2) [R=CH(SiMe(3))(2)] 3 and R(2)A l-C(NR')-AlR(2) (4 R'=C6H5; 5 R'=CMe(3)) with a sulfur atom or an ison itrile group inserted between the aluminium atoms. Compounds 4 and 5 w ere isolated in high yield by the reaction of 1 with the appropriate i sonitriles. By using an excess of phenyl isonitrile a dark red compoun d 6 is obtained with two isonitrile units inserted into the Al-Al bond and formation of a C-C single bond. According to crystal structure de terminations of 4 and 6 a three-membered heterocycle is formed by the interaction of the nitrogen lone-pair to one of the Al atoms in 4, whi le in 6 both Al atoms are four-coordinated by bonding to a nitrogen an d a carbon atom with formation of two across the C-C bond anellated fo ur-membered heterocycles. As shown by NMR spectroscopy the molecular s tructure of 4 with one stereochemically saturated and one unsaturated Al atom is unchanged in solution even upon heating to 100 degrees C.