Dimolybdenum complexes containing anions of N, N′-bis(pyrimidine-2-yl)formamidine and N-(2-pyrimidinyl)formamide

Abstract

The reactions of Mo 2(O 2CCH 3) 4 with different equivalents of N, N′-bis(pyrimidine-2-yl)formamidine (H L1) and N-(2-pyrimidinyl)formamide (H L2) afforded dimolybdenum complexes of the types Mo 2(O 2CCH 3)( L1) 2( L2) ( 1) trans-Mo 2( L1) 2( L2) 2 ( 2) cis-Mo 2( L1) 2( L2) 2 ( 3) and Mo 2( L2) 4 ( 4). Their UV–Vis and NMR spectra have been recorded and their structures determined by X-ray crystallography. Complexes 2 and 3 establish the first pair of trans and cis forms of dimolybdenum complexes containing formamidinate ligands. The L1 ligands in 1– 3 are bridged to the metal centers through two central amine nitrogen atoms, while the L2 ligands in 1– 4 are bridged to the metal centers via one pyrimidyl nitrogen atom and the amine nitrogen atom. The Mo–Mo distances of complexes 1 [2.0951(17) Å], 2 [2.103(1) Å] and 3 [2.1017(3) Å], which contain both Mo⋯N and Mo⋯O axial interactions, are slightly longer than those of complex 4 [2.0826(12)–2.0866(10) Å] which has only Mo⋯O interactions.