LONG-CHAIN SECONDARY DITHIOOXAMIDES AS LIGANDS FOR THE SYNTHESIS OF PLATINUM(II) METALLOMESOGENS

In the search for platinum complexes of secondary dithiooxamides (RNHC S)(2) (termed as R2H2DTO), showing metallomesogens properties, several [Pt(R2HDTO)(2)] were synthesised starting from cis-[Pt(Me2SO)(2)Cl-2] . The paper is mainly devoted to the co-ordination chemistry of long c hain dithiooxamides which in some cases show a different behaviour wit h respect to R2H2DTO bearing small substituents on nitrogen atoms. The observed reactivity appears related only in part to the lower basicit y of amide nitrogen atoms in diaryl- with respect to dialkyl-dithiooxa mides, and differently populated conformations of the complexes seem t o play an important role. Mesophase formation far [Pt(R2HDTO)(2)] with R=3,4-[CH3(CH2)(9)O](2)C6H3 and 3,4-[CH3(CH2)(11)O](2)C6H3 is suggest ed by polarising optical microscopy and differential scanning calorime try. The synthesis of analogous bis-chelates, but with two different d ithiooxamide ligands, is also described.