New insights into the chemistry of oxomolybdenum(VI) complexes with N-salicylidene-2-aminoethanol

Oxomolybdenum(VI) complexes with tridentate Schiff base, N-salicylidene-2-aminoethanol (H2sae), has been synthesised by the reaction of Mo(O)2(sal)2 (where Hsal=salicylic aldehyde) with 2-aminoethanol. This reaction leads to dimeric [MoO(μ-O)(sae)]2 and new monomeric [Mo(O)2(sae){1,2-O(−)C6H4C(H)N(+)(H)C2H4OH}] (1) compounds. Also substitution of acetylacetonate ligand in Mo(O)2(acac)2 by H2sae in EtOH leads to the same complexes (vide infra), but in MeOH monomeric compound Mo(O)2(sae)(MeOH) (2) was formed. The molecular structure of complexes 1 and 2 have been determined by X-ray studies, which confirm that one of the H2sae co-ordinates as η3-tridentate O,N,O′ ligand, while in complex 1 this ligand exists also in zwitterionic form with intramolecular hydrogen bonding, O⋯HN, 2.584(3) Å, of phenolic oxygen bonded to the molybdenum atom. The crystals of 1 are triclinic, space group , a=8.483(2) Å, b=10.187(3) Å, c=11.034(3) Å, α=105.26(2)°, β=95.29(2)°, γ=95.10(2)°, and Dcalcd=1.666(1) g cm−3 for Z=2. The crystals of 2 are monoclinic, space group P21/c, a=6.697(2) Å, b=7.375(2) Å, c=24.100(3) Å, β=92.76(5)°, and Dcalcd=1.805(1) g cm−3 for Z=4.