The structures of four MoO2Y complexes where Y2− is a linear tetradentate ligand containing N and S donor atoms are reported. The reaction of Mo(VI) starting materials with stoichiometric amounts of the appropriate YH2 ligand produced the MoO2Y complexes in good yield. The relevant crystallographic parameters for the title complexes are presented in Table I and summarized herein. [MoO2(SCH2CH2N(CH3)CH2CH2N(CH3)CH2CH2S)], [MoO2L], crystallized in the triclinic space group P1̄ with unit cell dimensions a = 7.169 (2) Å, b = 14.369 (4) Å, and c = 13.572 (4) Å and α = 95.72 (3)°, β = 97.12 (2)°, and γ = 111.80 (2)°, with Z = 4, to give a calculated density of 1.75 g/cm3 (observed density of 1.74 g/cm3). The structure was solved on the basis of 2609 reflections with Fo ≥ 6σ(Fo) and refined to final R values of 0.080 and 0.084. [MoO2(SCH2CH2N(CH3)CH2CH2CH2N(CH3)CH2CH2S)], [MoO2L′], crystallizes as yellow prisms in the monoclinic space group C2/c with unit cell dimensions a = 8.992 (3) Å, b = 12.468 (3) Å, and c = 12.204 (2) Å and β = 104.7 (1)°. The measured density of 1.72 g/cm3 was in good agreement with the value of 1.75 g/cm3 calculated on the basis of 4 molecules in the unit cell. The structure has been solved and refined to R values of 0.040 and 0.067 based on 1335 reflections with Fo ≥ 6σ(Fo). [MoO2(SC6H4NHCH2CH2NHC6H4S)], [MoO2L″], crystallizes in the monoclinic crystal system, space group P21/n, with unit cell dimensions a = 11.202 (3) Å, b = 11.468 (4) Å, and c = 16.033 (3) Å with β = 105.83 (2)° and Z = 4 to give a calculated density of 1.58 g/cm3 (observed density of 1.55 g/cm3). Structure solution and refinement were based on 4325 reflections with Fo ≥ 6σ(Ro) to give final R values of 0.051 and 0.044. The complex [MoO2(SCH2CH2NHCH2CH2SCH2CH2S)], [MoO2(SNSS)], crystallizes in the orthorhombic space group Pbca, with unit cell dimensions a = 13.787 (2) Å, b = 14.920 (2) Å, and c = 10.665 (2) Å, with Z = 8 and a calculated density of 1.84 g/cm3 (observed density of 1.85 g/cm3). Structure refinement based on 1870 unique reflections with Fo ≥ 6.σ(Fo) converged to R values of 0.028 and 0.023. The structural studies reveal that the molecules possess the usual cis-dioxo MoO22+ core and that the ligands are present as tetradentate donors coordinating through thiolate sulfur and amine nitrogen groups and, in the case of [MoO2(SNSS)], through thioether sulfur also. The structure of [MoO2L] reveals two crystallographically independent molecules in the asymmetric unit with nonequivalent Mo-S or Mo-N bond distances, in contrast to other structures with the MoO22+ core. On the other hand, [MoO2L′] displays crystallographically equivalent Mo-S distances, but an unusually long Mo-N bond length of 2.486 (5) Å. Comparison of the above two structures to that of the related species [MoO2″] suggests that minor ligand variations cause significant differences in the static structural behavior of the Mo(VI) complexes. The effects of drastic changes in the nature of the ligand donor groups are revealed in the structure of [MoO2(SNSS)], where an amine nitrogen donor has been replaced by a thioether sulfur. The most notable feature of the structure is the Mo-S(thioether) bond distance of 2.708 (1) Å. The geometries of the title complexes are compared to those previously reported for species containing the MoO22+ core.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry