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

The reactions of Mo2(O2CCH3)4 with different equivalents of N,N′-bis(pyrimidine-2-yl)formamidine (HL1) and N-(2-pyrimidinyl)formamide (HL2) afforded dimolybdenum complexes of the types Mo2(O2CCH3)(L1)2(L2) (1) trans-Mo2(L1)2(L2)2 (2) cis-Mo2(L1)2(L2)2 (3) and Mo2(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.

Graphical abstractThe reactions of Mo2(O2CCH3) with different equivalents of N,N′-bis(pyrimidine-2-yl)formamidine (HL1) and N-(2-pyrimidnyl)formamide (HL2) afforded complexes of the types Mo2(O2CCH3)(L1)2 (L2) (1) trans-Mo2(L1)2 (L2)2 (2) cis-Mo2(L1)2 (L2)2 (3) and Mo2(L2)4 (4). Complexes 2 and 3 establish the first pair of cis and trans forms of dimolybdenum complexes containing formamidinate ligands. The Mo–Mo distances of complexes 1–3, which contain both Mo⋯N and Mo⋯O axial interactions, are slightly longer than those of complex 4 which has only Mo⋯O interactions.Figure optionsDownload full-size imageDownload as PowerPoint slide