TY - JOUR
T1 - Derivatized polyoxomolybdates. Synthesis and characterization of oxomolybdate clusters containing coordinatively bound diazenido units. Crystal and molecular structure of the octanuclear oxomolybdate (NHEt3)2(n-Bu4N)2[Mo 8O20(NNPh)6] and comparison to the structures of the parent ...
AU - Hsieh, Tze Chen
AU - Shaikh, Shahid N.
AU - Zubieta, Jon
PY - 1987
Y1 - 1987
N2 - Full title: Derivatized polyoxomolybdates. Synthesis and characterization of oxomolybdate clusters containing coordinatively bound diazenido units. Crystal and molecular structure of the octanuclear oxomolybdate (NHEt3)2(n-Bu4N)2[Mo 8O20(NNPh)6] and comparison to the structures of the parent oxomolybdate α-(n-Bu4N)4[Mo8O26] and the tetranuclear (diazenido)oxomolybdates (n-Bu4N)2[Mo4O10(OMe) 2(NNPh)2] and (n-Bu4N)2[Mo4O8(OMe) 2(NNC6H4NO2)4]. Reactions of α-(n-Bu4N)4[Mo8O26] with phenylhydrazine yield a variety of derivatized polyoxomolybdates containing the cis-bis(diazenido)molybdenum core [Mo(NNPh)2]2+. When the reaction is carried out in methanol with excess (p-nitrophenyl)-hydrazine, (n-Bu4N)2[Mo4O8(OMe) 2(NNAr)4] is the major product. The tetranuclear polyoxomolybdate unit consists of the [Mo2(μ-OMe)2(NNAr)4]2+ core, bridged by two doubly bridging bidentate [MoO4]2- moieties. On the other hand, when the molybdate is present in excess, the unsymmetrically substituted tetranuclear cluster (n-Bu4N)2[Mo4O10(OMe) 2(NNPh)2] is isolated. This species is structurally analogous to [Mo4O8(OMe)2(NNPh)4]2-, presenting the [Mo2O2(μ-OMe)2(NNPh)2] 2+ core, and is characterized by a cis-[MoO2]2+ unit and a single cis-[Mo(NNPh)2]2+ unit, bridged by two methoxy groups. The tetranuclear unit is completed by the doubly bridging [MoO4]2- units. In contrast, reactions of phenylhydrazine and NEt3 with α-(n-Bu4N)4[Mo8O26] in acetonitrile yield the octanuclear polyoxomolybdate (NHEt3)2(n-Bu4N)2[Mo 8O20(NNPh)6]. The structure is related to that of the α-[Mo8O26]4- parent polyoxomolybdate, by substitution of the two terminal oxo groups on each of three alternate molybdenum centers in the Mo6O6 crown and rotation of the pole-capping [MoO4]2- units by ca 45°, so as to engage three doubly bridging Mo2O interactions per unit rather than three triply bridging Mo3O interactions. The 17O NMR spectra of the derivatized species are consistent with the solid-state structures, exhibiting resonances in the regions assigned to doubly bridging Mo2O groups (400-520 ppm) and to terminal MoO groups (700-950 ppm) Crystal data are as follows. α-(n-Bu4N)4[Mo8O26]: monoclinic space group P21/n, with a = 15.093 (3) Å, b = 16.011 (3) Å, c = 18.519(4) Å, β = 91.36 (1)°, V = 4473.9 (3) Å3 and Z = 2. Structure solution based on 3274 reflections converged at R = 0.039. (n-Bu4N)2[Mo4O8-(OMe) 2(NNC6H4-p-NO2)4]: monoclinic space group P21/n, with a = 15.723 (2) Å, b = 14.058 (2) Å, c = 16.607 (3) Å, β = 95.28 (1)°, V = 3655.1 (2) Å3 and Z = 2. Structure solution and refinement based on 2988 reflections converged at R = 0.063. (n-Bu4N)2[Mo4O10(OMe) 2(NNPh)2]: monoclinic space group C2/c, with a = 15.472 (2) Å, b = 20.516 (3) Å, c = 19.077 (2) Å, β = 91.23 (1)° V = 6054.1 (2) and Z = 4. Structure solution and refinement based on 1670 reflections converged at R = 0.066. (NHEt3)2(n-Bu4N)2[Mo 8O20(NNPh)6]: P21/c with a = 18.495 (3) Å, b = 26.783 (5) Å, c = 21.470 (4) Å, β = 95.57 (1)°, V = 10585.0 (9) Å3, and Z = 4; 6525 reflections, R = 0.051.
AB - Full title: Derivatized polyoxomolybdates. Synthesis and characterization of oxomolybdate clusters containing coordinatively bound diazenido units. Crystal and molecular structure of the octanuclear oxomolybdate (NHEt3)2(n-Bu4N)2[Mo 8O20(NNPh)6] and comparison to the structures of the parent oxomolybdate α-(n-Bu4N)4[Mo8O26] and the tetranuclear (diazenido)oxomolybdates (n-Bu4N)2[Mo4O10(OMe) 2(NNPh)2] and (n-Bu4N)2[Mo4O8(OMe) 2(NNC6H4NO2)4]. Reactions of α-(n-Bu4N)4[Mo8O26] with phenylhydrazine yield a variety of derivatized polyoxomolybdates containing the cis-bis(diazenido)molybdenum core [Mo(NNPh)2]2+. When the reaction is carried out in methanol with excess (p-nitrophenyl)-hydrazine, (n-Bu4N)2[Mo4O8(OMe) 2(NNAr)4] is the major product. The tetranuclear polyoxomolybdate unit consists of the [Mo2(μ-OMe)2(NNAr)4]2+ core, bridged by two doubly bridging bidentate [MoO4]2- moieties. On the other hand, when the molybdate is present in excess, the unsymmetrically substituted tetranuclear cluster (n-Bu4N)2[Mo4O10(OMe) 2(NNPh)2] is isolated. This species is structurally analogous to [Mo4O8(OMe)2(NNPh)4]2-, presenting the [Mo2O2(μ-OMe)2(NNPh)2] 2+ core, and is characterized by a cis-[MoO2]2+ unit and a single cis-[Mo(NNPh)2]2+ unit, bridged by two methoxy groups. The tetranuclear unit is completed by the doubly bridging [MoO4]2- units. In contrast, reactions of phenylhydrazine and NEt3 with α-(n-Bu4N)4[Mo8O26] in acetonitrile yield the octanuclear polyoxomolybdate (NHEt3)2(n-Bu4N)2[Mo 8O20(NNPh)6]. The structure is related to that of the α-[Mo8O26]4- parent polyoxomolybdate, by substitution of the two terminal oxo groups on each of three alternate molybdenum centers in the Mo6O6 crown and rotation of the pole-capping [MoO4]2- units by ca 45°, so as to engage three doubly bridging Mo2O interactions per unit rather than three triply bridging Mo3O interactions. The 17O NMR spectra of the derivatized species are consistent with the solid-state structures, exhibiting resonances in the regions assigned to doubly bridging Mo2O groups (400-520 ppm) and to terminal MoO groups (700-950 ppm) Crystal data are as follows. α-(n-Bu4N)4[Mo8O26]: monoclinic space group P21/n, with a = 15.093 (3) Å, b = 16.011 (3) Å, c = 18.519(4) Å, β = 91.36 (1)°, V = 4473.9 (3) Å3 and Z = 2. Structure solution based on 3274 reflections converged at R = 0.039. (n-Bu4N)2[Mo4O8-(OMe) 2(NNC6H4-p-NO2)4]: monoclinic space group P21/n, with a = 15.723 (2) Å, b = 14.058 (2) Å, c = 16.607 (3) Å, β = 95.28 (1)°, V = 3655.1 (2) Å3 and Z = 2. Structure solution and refinement based on 2988 reflections converged at R = 0.063. (n-Bu4N)2[Mo4O10(OMe) 2(NNPh)2]: monoclinic space group C2/c, with a = 15.472 (2) Å, b = 20.516 (3) Å, c = 19.077 (2) Å, β = 91.23 (1)° V = 6054.1 (2) and Z = 4. Structure solution and refinement based on 1670 reflections converged at R = 0.066. (NHEt3)2(n-Bu4N)2[Mo 8O20(NNPh)6]: P21/c with a = 18.495 (3) Å, b = 26.783 (5) Å, c = 21.470 (4) Å, β = 95.57 (1)°, V = 10585.0 (9) Å3, and Z = 4; 6525 reflections, R = 0.051.
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M3 - Article
AN - SCOPUS:0001186741
SN - 0020-1669
VL - 26
SP - 4079
EP - 4089
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 24
ER -