New Classes of Functionalized Polyoxometalates: Organo-Nitrogen Derivatives of Lindqvist Systems

Synthesis, spectroscopic studies and crystal structure of a polyoxoanion cluster incorporating para-bromophenylimido ligand, (Bu4N)2[Mo6O18(NC6H4Br-p)]

“…À218 (17) 5688 (13) 1501 (11) 121(8) C (4) À753 (13) 6129 (11) 1702 (11) 84(6) C (5) À1255 (13) 5826 (12) 2037(11) 100(7) C(6) À1268 (13) 5071 (14) 2149(11) 108(7) Br À788 (2) 7159 (1) 1525 (2) 177 (2) U esq is defined as one-third of the trace of the orthogonalized U ij tensor. Table 3 Selected bond lengths (Å ) and angles (°) for 1 shifts, indicating the much weaker shielding nature of the [Mo 5 O 18 (Mo"N-)] 2À than the amino group NH 2 À .…”

“…Mo (1) À585 (1) 2859 (1) 2156 (1) 68 (1) Mo (2) À1081 (1) 1530 (1) 3057 (1) 49 (1) Mo (3) À1272 (1) 1266 (1) 1303 (1) 57 (1) Mo (4) 691 (1) 1746 (1) 1808 (1) 51 (1) Mo (5) 876 (1) 2023 (1) 3561 (1) 56 (1) Mo (6) 209 (1) 395 (1) 2726 (1) 50 (1) O (1) À194 (5) 1659 (4) 2437 (4) 37 (2) O (2) À1694 (6) 1453 (6) 3513 (6) 75 (3) O(3) À2030 (6) 961 (8) 503 (6) 94 (4) O (4) 1322 (6) 1803 (6) 1360 (6) 73(3) O(5) 1670 (6) 2289 (7) 4374 (5) 86 (4) O(6) 480 (7) À502 (6) 2927 (6) 82 …”

“…Up to date, a number of organoimido derivatives of Lindqvist type polyoxometalates [4] such as the hexamolybdate ion, [Mo 6 O 19 ] 2À and hexatungstate ion, [W 6 O 19 ] 2À , have been directly or indirectly synthesized via three types of reactions, which include reactions with phosphinimines [5], isocyanates [6] and aromatic amines [7] or aromatic amines plus N,N 0 -dicyclohexylcarbodiimide [8]. However, such donor-acceptor systems usually require that their ligands must be charge donors.…”

“…The organoimido derivatives of polyoxometalates have gained tremendous interest in the last decade owing to their unusual structure, electrochemical, magnetic, catalytic, anti-microbial and anti-tumor properties [1][2][3][4]. Up to date, a number of organoimido derivatives of Lindqvist type polyoxometalates [4] such as the hexamolybdate ion, [Mo 6 O 19 ] 2À and hexatungstate ion, [W 6 O 19 ] 2À , have been directly or indirectly synthesized via three types of reactions, which include reactions with phosphinimines [5], isocyanates [6] and aromatic amines [7] or aromatic amines plus N,N 0 -dicyclohexylcarbodiimide [8].…”

A new class of functionalized polyoxometalates: synthesis, structure and preliminary antitumor activity studies of three arylimido substituted hexamolybdates bearing a strong electron-withdrawing nitro group, (Bu4N)2[Mo6O18(NAr)] (Ar = 3-NO2-C6H4, 2-CH3-4-NO2-C6H3, 2-CH3-5-NO2-C6H3)

“…16 The surface modification of POMs with organic species 17 has attracted considerable attention in recent years, because it affords a convenient and effective way to generate novel organic/inorganic hybrid materials with their fascinating properties, resulting from synergistic effects between the organic and inorganic segments. 9, 18 In this respect, the field of organoimido derivatives of POMs has gained more and more interest 19 after the outstanding reports of Maatta, 20 Errington, 21 and Proust, 22 inasmuch as in such compounds, the organic p electrons may extend their conjugation to the inorganic framework, remarkably modifying the electronic structure and redox properties of the parent POM clusters. 18a,20c, 23 Organoimido derivatives of POMs are usually obtained through three types of reaction with phosphinimines, 20a, 22 isocyanates, 20b,21a and aromatic amines 21b, 23,24 as imido-releasing reagents, respectively.…”