Synthesis and crystal structures of nickel(II) and palladium(II) complexes with o-carboranyl amidine ligands

A number of new nido-carboranyl amidines 10-R(CH2)(n)NHC(Et)=HN-7,8-C2B9H11 (n = 2, R = OH, OMe, and NMe2; n = 3, R = OH) were synthesized by the nucleophilic addition of amino alcohols and N,N-dimethylethylenediamine to the highly activated -C N+- triple bond of the 10-propionitrilium derivative of nido-carborane. A similar reaction of 10-EtCuN-7,8-C2B9H11 with ethylenediamine unexpectedly resulted in the cleavage of the C N bond to form the ammonium derivative 10-H3N-7,8-C2B9H11. The complexation of the synthesized carboranyl amidines 10-MeO(CH2)(2)NHC(Et)vHN-7,8-C2B9H11 and 10-Me2N(CH2)(2)NHC(Et)vHN-7,8-C2B9H11 with nickel and palladium phosphine complexes [(Ph3P)(2)MCl2] (M = Ni, Pd) was studied. The reactions with 10-MeO(CH2)(2)NHC(Et)vHN-7,8-C2B9H11 result in half-sandwiched metallacarborane complexes with the retention of one triphenylphosphine ligand [3-Ph3P-3-(8MeOCH(2)CH(2)N=C(E t)NH)-3,1,2-MC2B9H10], while the reactions with 10-Me2N(CH2)(2)NHC(Et)vHN-7,8-C2B9H11 proceed with the complete loss of the phosphine ligands and lead to the formation of complexes with the eta(5):kappa(2)(N,N')-coordinated carboranyl amidine ligand [3,3-(8-Me2NCH2CH2N=C(Et)NH)-3,1,2-MC2B9H10]. The crystal molecular structures of the synthesized complexes were determined by single crystal X-ray diffraction.

Automated summary

A series of new nido-carboranyl amidines were synthesized and their reactions with nickel and palladium phosphine complexes were studied. The results showed that the reaction products of different carboranyl amidines exhibited different coordination modes with the metal centers.