The authors' review compiles the literature in the field of polyoxomolybdates, POMo, and polyoxomolybdovanadates, POMoV, over the past two decades. The main achievements in the field of synthesis, ...crystal and molecular structure determinations and applications are presented. The first section describes polyoxomolybdates; their structure starting with a smaller number of building units to the formation of new structural shapes of polyoxomolybdate clusters of supramolecular arhitecture. Polyoxomolybdates include the compounds with various organic ligands, functionalized polyoxomolybdates and a number of organo-inorganic clusters. Recent synthetic methods such as functionalization and hydrothermal/solvothermal synthesis with a possibility to control the size and shape of the resulting structure are reviewed. The design and synthesis of inorganic-organic hybrid compounds in which POMo anions are combined with organic molecular cations appears as the most successful approach for preparing novel types of molecular based materials with functional properties. The second section covers the polyoxomolybdovanadate compounds from structure to synthesis. Interesting compounds with the molybdenum-rich region or vanadium rich-region, mixed vanadium-molybdenum polyoxoanions with various oxidation states of the metal atoms and the organic-inorganic hybrid materials are described. The last section reviews the application of the before mentioned compounds. Due to the functionalization of the complexes potential utility in biology and medicine, catalysis and material science is significantly increased. Finally, the importance of large polyoxometalate clusters as target nanosized molecular materials, which present a challenge for the future complex chemistry, is discussed. PUBLICATION ABSTRACT
Polynuclear MoO
2{SalTSC-4-Me}
n
, MoO
2{VanTSC-4-Me}
n
and mononuclear MoO
2{SalTSC-4-Me}(CH
3OH), MoO
2{VanTSC-4-Me}(CH
3OH) and MoO
2{VanTSC-4-Me}(H
2O)
·
CH
3CN complexes have been prepared by ...the reaction of MoO
2(acac)
2 with salicylaldehyde 4-methylthiosemicarbazone or 3-methoxy-salicylaldehyde 4-methylthiosemicarbazone in acetonitrile or in dry methanol.
Polynuclear MoO
2{SalTSC-4-Me}
n
(
I), MoO
2{VanTSC-4-Me}
n
(
II) and mononuclear MoO
2{SalTSC-4-Me}(CH
3OH) (
1a), MoO
2{VanTSC-4-Me}(CH
3OH) (
2a) and MoO
2{VanTSC-4-Me}(H
2O)
·
CH
3CN (
2b) complexes have been prepared by the reaction of the MoO
2(acac)
2 (acetylacetonate ligand, acac
−, C
5H
7O
2
−) with
1 (salicylaldehyde 4-methylthiosemicarbazone ligand, C
6H
4(OH)CH:NNC(SH)NHCH
3H
2SalTSC-4-Me) or
2 (3-methoxy-salicylaldehyde 4-methylthiosemicarbazone, CH
3OC
6H
3(OH)CH:NNC(SH)NHCH
3, H
2VanTSC-4-Me) in acetonitrile or in dry methanol. All complexes have been characterized by means of chemical analyses, thermogravimetric analyses, IR spectroscopy and some of them by
1H,
13C NMR spectroscopy and X-ray crystallography. In all mononuclear complexes molybdenum atom is coordinated by two terminal oxo-oxygen atoms, by ONS atoms from the ligand molecule and by an oxygen atom from methanol (in
1a and
2a) or water (in
2b) molecules. Ligands
1 and
2 have been characterized by means of
1H,
13C NMR spectroscopy and X-ray crystallography. Molecules of both ligands are found to be in the thioketo tautomeric form.
Mononuclear MoO
2{C
6H
4(O)CH:NNC(S)NH
2}(D) and MoO
2{C
6H
4(O)CH:NNHC(S)NH}(CH
3OH)
·
CH
3OH
·
1/2D and dinuclear MoO
2{C
6H
4(O)CH:NNC(S)NH
2}(D)
2 molybdenum(VI) complexes have been prepared by ...the reaction of MoO
2(C
5H
7O
2)
2 C
5H
7O
2
=
acetylacetonate ion with salicylaldehyde thiosemicarbazone (C
6H
4(OH)CH:NNC(SH)NH
2) and Lewis base (D) e.g., pyridine, γ-picoline or 4,4′-bipyridine in dry methanol. All complexes have been characterized by means of chemical analyses, IR spectroscopy, thermogravimetric analyses and some of them by X-ray crystallography.
Mononuclear molybdenum(VI) complexes of the type MoO
2{C
6H
4(O)CH:NNC(S)NH
2}(D) D
=
pyridine (
1d), γ-picoline (
1c) and MoO
2{C
6H
4(O)CH:NNHC(S)NH} (CH
3OH)
·
CH
3OH
·
1/2bpy (
1e) have been prepared by the reaction of MoO
2(C
5H
7O
2)
2 (C
5H
7O
2
=
acetylacetonate ion) with salicylaldehyde thiosemicarbazone C
6H
4(OH)CH:NNC(SH)NH
2 and Lewis base in dry methanol. The dinuclear complex MoO
2{C
6H
4(O)CH:NNC(S)NH
2}
2 (
1b) has been prepared by the reaction of MoO
2(C
5H
7O
2)
2 with salicylaldehyde thiosemicarbazone C
6H
4(OH)CH:NNC(SH)NH
2 in dry dichloromethane. In all complexes, except in the case of complex
1e, molybdenum is coordinated by two terminal oxo-oxygen atoms, (O
t), by ONS atoms from the salicylaldehyde thiosemicarbazone ligand and by an oxygen atom from the methanol molecule in
1a, and either by a nitrogen atom from γ-picoline in
1c or pyridine in
1d. In MoO
2{C
6H
4(O)CH:NNHC(S)NH}(CH
3OH)
·
CH
3OH
·
1/2bipy (
1e), salicylaldehyde thiosemicarbazone is coordinated to molybdenum through ONN atoms, while the sixth coordination site around the molybdenum atom is completed by the methanol molecule.
All complexes have been characterized by means of chemical and thermogravimetric analyses and IR spectroscopy. The molecular structures of complexes
1b,
1c and
1e have been determined by a single crystal X-ray diffraction method.
The crystal structures of γ-type octamolybdates Na
4Mo
8O
26(alaO)
2
·
18H
2O (
I), Na
4Mo
8O
26(glyglyO)
2
·
15H
2O (
II) and Na
4Mo
8O
26(glyglyO)
2
·
12H
2O (
III) have been determined by X-ray ...structure analysis. These compounds are tested against different carcinoma cells in vitro. All tested compounds showed a differential cell-growth inhibition in a dose-dependent manner selectively on HepG2 and MCF-7 cell lines.
γ-Type octamolybdates of the formulae, Na
4Mo
8O
26(alaO)
2
·
18H
2O (
I), Na
4Mo
8O
26(glyglyO)
2
·
15H
2O (
II) and Na
4Mo
8O
26(glyglyO)
2
·
12H
2O (
III) have been prepared from sodium molybdate in aqueous solution by adding
dl-alanine or glycylglycine. Their crystal structures have been determined by X-ray structure analysis.
dl-alanine and glycylglycine coordinate molybdenum atom in γ-octamolybdate Mo
8O
26
4− anions via monodentate carboxylate-oxygen atom. The prepared octamolybdates were screened for the possible antiproliferative activity on a panel of five tumor cell lines and on a normal cell line. All tested compounds showed a differential cell-growth inhibition in a dose-dependent manner selectively on hepatocellular carcinoma cell line (HepG2) and breast cancer cell line (MCF-7).
Mononuclear MoO2LD, and dinuclear MoO2L2 or MoO2L2 · D dixomolybdenum(VI) complexes have been prepared by the reaction of tridentate Schiff‐base ligands L with MoO2(acac)2. The Schiff‐base ligands ...have been synthesized from salicylaldehyde (1, 1a, 1c, 1d), 2‐hydroxy‐1‐naphthaldehyde (2, 2c) and 2‐hydroxy‐3‐methoxybenzaldehyde (3a, 3b, 3c, 3d, 3e) with 2‐amino‐p‐cresol. All prepared complexes consist of cis‐MoO22+core coordinated by Schiff‐base ligand through two deprotonated hydroxyl groups and one imino nitrogen atom. The usual octahedral coordination around the molybdenum atoms is completed by the neutral ligand D (methanol, ethanol, dimethyl sulfoxide, imidazole or 4, 4′‐bipyridine). All compounds were characterized by elemental analyses, IR spectroscopy and some of them by X‐ray crystallography (1a, 2c, 3a, 3b, 3c and 3e).
Synthese, Charakterisierung und Kristallstrukturen von ein‐ und zweikernigen Dioxomolybdän‐Komplexen mit dreizähnigen Schiff‐Basen‐Liganden, Teil 2
Einkernige und zweikernige Typen von Dioxomolybdän(VI)‐Komplexen MoO2LD, MoO2L2 und MoO2L2 · D wurden durch Reaktion dreizähniger Schiff‐Basen‐Liganden L mit MoO2(acac)2 hergestellt. Die Schiff‐Basen‐Liganden wurden aus Salicylaldehyd (1, 1a, 1c, 1d), 2‐Hydroxy‐1‐naphthaldehyd (2, 2c) und 2‐Hydroxy‐3‐methoxybenzaldehyd (3a, 3b, 3c, 3d, 3e) mit 2‐Amino‐p‐Kresol synthetisiert. Alle Komplexe enthalten die cis‐MoO22+‐Gruppe, die durch zwei deprotonierte Hydroxylgruppen und ein Imino‐Stickstoffatom der Schiff‐Base‐Liganden koordiniert ist. Die oktaedrische Koordination der Molybdänatome wird durch die Neutralliganden D (Methanol, Ethanol, Dimethylsulfoxid, Imidazol oder 4, 4′‐Bipyridin) vervollständigt. Die Komplexe werden durch Elementaranalysen, IR‐Spektroskopie und einige von ihnen durch Kristallstrukturanalysen (1a, 2c, 3a, 3b, 3c und 3e) charakterisiert.
Mononuclear and polynuclear dioxomolybdenum(VI) complexes with Schiff base ligands have been prepared by the reaction of MoO2(acac)2 with salicylaldehyde (1 and 4), 2‐hydroxy‐1‐naphthaldehyde (2 and ...5) and 2‐hydroxy‐3‐methoxybenzaldehyde (3 and 6) with addition of appropriate amine. All prepared complexes of the general formulae MoO2LD and MoO2Ln consist of cis‐MoO22+ core coordinated by Schiff‐base ligand (L) in a tridentate manner through two deprotonated hydroxyl groups and one imino nitrogen. The usual octahedral coordination around molybdenum atom is completed by monodentate solvent molecules D (methanol, ethanol or dimethylsulphoxide). All compounds were characterized by means of chemical analysis, IR spectroscopy, thermogravimetric analysis and some of them by X‐ray crystallography (1a, 2c, 3a, 4c and 6c).
Eine Reihe von Molybdän(VI)‐Komplexen mit dreizähnigen Schiff‐Basen‐Liganden
Ein‐ und vielkernige Dioxomolybdän(VI)‐Komplexe mit Schiff‐Basen‐Liganden wurden durch Reaktion von MoO2(acac)2 mit Salicylaldehyd (1 und 4), 2‐Hydroxy‐1‐naphthaldehyd (2 und 5) und 2‐Hydroxy‐3‐methoxybenzaldehyd (3 und 6) durch Zugabe von Amin hergestellt. Alle Komplexe der allgemeinen Formeln MoO2LD und MoO2Ln enthalten die cis‐MoO22+‐Einheit, die durch die Schiff‐Basen‐Liganden dreifach durch zwei deprotonierte Hydroxyl‐Gruppen und durch ein Imino‐Stickstoffatom koordiniert ist. Die übliche oktaedrische Koordination am Molybdänatom wird durch einzähnige Solvens‐Moleküle D (Methanol, Ethanol oder Dimethylsulfoxid) ergänzt. Alle Verbindungen werden durch Elementaranalysen, IR‐Spektren, thermogravimetrische Analysen und einige von ihnen durch Kristallstrukturanalysen (1a, 2c, 3a, 4c und 6c) charakterisiert.
Two enaminones ethyl 4-(4-hydroxy-6-methyl-2
H-pyran-2-on-3-yl)-2-(tryptamino)-4-oxo-2-butenoate (
HL
1
) and 3-(1-tryptaminoetylidene)-6-methyl-2
H-pyran-2,4(3H)-dione (
HL
2
) have been prepared by ...the reactions of tryptamine with 2-hydroxy-4-(4-hydroxy)-6-methyl)-2
Hbb-pyrane-2-on-3-yl)-4-oxo-2-butenoate (ehmpb) or with dehydroacetic acid (dha). The NMR spectroscopy confirmed that both tautomeric forms of
HL
1
:
endo-enol (tautomer A with hydroxyl group at position 4) and
exo-enol form (tautomer B with hydroxyl group at position 7) are present in the DMSO-
d
6 solution. The molecular and crystal structure as well as the NMR data of
HL
2
showed that the condensation of dha and tryptamine occurs at acetyl-carbonyl and not at the pyrone-carbonyl group. Also new dinuclear Mo
2O
4(L
1)
2(CH
3OH)
2 (
1) and hexanuclear molybdenum(V) complexes (C
10H
12NH)Mo
6O
12(OCH
3)
4(acac)
3 (
2) have been prepared by the reactions of Mo
2O
3(acac)
4 (acac=acetilacetonate ion) with
HL
1
or with tryptamine. All compounds have been characterized also by means of elemental analyses, IR spectroscopy as well as by thermal analyses.
The reaction of molybdenum(VI) oxide with oxalic acid or alkali oxalate and alkali halides results in the formation of two series of molybdenum(VI) oxalate complexes: one of the general formula M
2Mo
...2O
5(C
2O
4)
2(H
2O)
2 containing the Mo
2O
5 core and the other of the formula M
2MoO
3(C
2O
4) with a MoO
3 core (M=Na, K, Rb, Cs). Both series were characterized by chemical analysis, ESR, UV and IR spectroscopy, thermogravimetry, differential scanning calorimetry, X-ray powder method and some of them by single-crystal X-ray structure analysis. Complexes of the first series adopt dimeric structures, the second series infinite polymeric structures. In both types of structures molybdenum ions are six-coordinated being surrounded by terminal oxo-oxygens, bridging oxygens and bidentate bonded oxalate ligands. When exposed to UV light all these complexes in the solid state exhibit photochromic behavior changing color from colorless to green–brown. These changes are remarkably more pronounced in the complexes with dimeric structures. There is definite correlation between their coloration and the UV induced ESR signal indicative for molybdenum(V). Such behavior is explained by the partial reduction of Mo(VI) to Mo(V) only at the crystal surfaces. This is also the explanation why K
2Mo
2O
5(C
2O
4)
2(H
2O)
2 was so far described as being red or pale reddish tan. All attempts to prepare the corresponding lithium complexes were unsuccessful. They are most probably very unstable because of the small radius of the lithium ion.
