para-Ethynyl aniline as a building block for fully π-conjugated ligands and acetylide complexes: crystal structures of trans-[Pt(PPh3)2(CCC6H4NH2)2] and [(μ-H)Ru3(CO)9(μ3-CCC6H4NH2)]

para-Ethynyl aniline has been prepared, structurally characterised and investigated as a building block towards fully π-conjugated multifunctional ligands and complexes. Palladium–copper catalysed coupling with aryl halides affords a number of new amino-substituted aryl acetylenes, while using [Ni(CO)2(PPh3)2] as a catalyst, cyclotrimerisation and dimerisation to give an ene-yne were competitive. Reaction of para-ethynyl aniline with low-valent metal centres affords acetylide complexes trans-[Pt(PR3)2(CCC6H4NH2)2] (R=Ph, Bun), cis-[Pt(η2-dppe)(CCC6H4NH2)2], all trans-[Ru(CO)2(PEt3)2(CCC6H4NH2)2] and [(μ-H)Ru3(CO)9(μ3-CCC6H4NH2)]. The bis(acetylide) trans-[Pt(PPh3)2(CCC6H4NH2)2] has been used to prepare extended chain complexes with amide, imine, imino-phosphorane and ferrocenyl imine units being generated. Attempts to prepare polymers via reaction with terephthaloyl chloride lead only to the formation of oligomers with an average of four monomer units.