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Dinuclear Oxomolybdate(V) Species with Oxalato and Pyridine Ligands Revisited: cis/trans Isomerization of [Mo2O4(η2‐C2O4)2(R‐Py)2]2– (R‐Py = Pyridine, Alkyl‐Substituted Pyridine) in Water Evidenced by NMR Spectroscopy

“…Both molybdenum starting materials possess labile sites (aqua and halo ligands), which in the mixtures of pyridine and methanol undergo a facile substitution chemistry with the formation of the {Mo 2 O 4 } 2+ structural unit or discrete clusters, as demonstrated before. [3] With a sufficient amount of oxalate, i.e. a ligand to metal ratio greater than 1, the formation of…”

“…[14] The pyridinium salt of this anion has also been reported, but with a different composition, H(PyH) 3 [14] and cis-NaCs 3 …”

“…Both reactions were exploited in the preparation of trans-(PyH) 2 ligands, the metal centers attain coordinative saturation through further assembly of {Mo 2 O 4 } 2+ units which share their originally μ 2 -bridging oxo groups to form discrete oligonuclear clusters. [3] For instance, the association of four {Mo 2 O 4 } 2+ units through the agency of methoxide ions has been shown to produce two different types of octanuclear metal oxide cores: (i) a ring-like {Mo 8 O 8 (μ 2 -O) 8 (μ 2 -OCH 3 ) 8 }, [4,5] and (ii) a more compact {Mo 8 O 8 (μ 3 -O) 4 (μ 2 -O) 4 (μ 3 -OCH 3 ) 2 (μ 2 -OCH 3 ) 4 } 2+ core. [6] In the presence of suitable ligands, their ligation to the {Mo 2 O 4 } 2+ core normally precedes the self-assembly of dinuclear subunits.…”

En route to {Mo2O2(μ2-O)2}2+ species: Isolation and structural characterization of a novel methoxide-bridged Mo(V) complex

“…The formation of the Mo(V) clusters may be envisioned as a stepwise condensation of dinuclear {Mo 2 O 2 (l 2 -O) 2 } 2+ fragments, enabled by the ability of oxygen donor atoms to participate in bridging interactions with two, three or even four metal atoms. In contrast to others, we have been focused on the preparation of the Mo(V) clusters directly from the Mo(V) precursors [6]. Compared to the commonly adopted synthetic procedure, i.e.…”

pH Dependent formations of dinuclear molybdenum(V) and incomplete cubane molybdenum(IV) complexes with nitrilotriacetate

“…The two reactions proceed as follow: The formations of 1 and 2 show a pH dependent reaction pattern. As the [Mo 2 O 4 ] 2+ core is a dominant fragment in +5 oxidation state of molybdenum(V) complexes [9,10], no other form of species are isolated like monomer of molybdenum(VI) complex K 3 [MoO 3 (nta)] AE H 2 O [11]. In acidic solutions of pH 4.0-5.0, the mixture of nitrilotriacetic acid and molybdate(VI) salt can be reduced by the addition of hydrazine hydrochloride.…”