Structural and mechanistic studies of co-ordination compounds. Part 29. Synthesis and characterization of some cis-macrocyclic secondary amine complexes of ruthenium

Abstract

Under suitably controlled conditions, the reaction between trioxalatoruthenate(III), [Ru(O4C2)3]3-, and 1,4,8,11-tetra-azacyclotetradecane (L1) in the presence of an acid HX leads to the formation of the corresponding cis-[RuL1X2]+ (X = Cl or Br) in ca. 50% yield. Other complexes of the type cis-[RuL1(X)Y]+ [(X)Y = I2, (NCS)2, (Br)Cl, or oxalate] have been obtained from either the dichloro- or the dibromo-complex by metathetical procedures. The ion cis-[RuL1(NCS)2]+ can easily be reduced and the product cis-[RuL1(NCS)2]·H2O has been isolated and characterized. The reaction of [Ru(O4C2)3]3- with 1,4,8,12-tetra-azacyclopentadecane (L2) in HBr yields cis-[RuL2Br2]+, but its reactions with open-chain tetramines, 3,7-diazanonane-1,9-diamine (L3) and 4,7-diazadecane-1,10-diamine (L4), in the presence of HX (X = Cl or Br) only resulted in the formation of the corresponding trans-dihalogeno-complexes. The assignment of a cis configuration to these complexes has been made on the basis of i.r. and electronic absorption spectroscopy. The 1H n.m.r. spectrum of cis-[RuL1(NCS)2]·H2O is consistent with a cis configuration.