Dithiolene dimetallic molybdenum(v) complexes displaying intraligand charge transfer (ILCT) emission

Abstract

Bifunctional dithiolene ligands have been coordinated to the Mo(V)(O)(μ-S2)Mo(V)(O) unit to afford [Mo2O2(μ-S)2(BPyDTS2)2](2-) (1(2-)) (BPyDTS2 (2-bis-(2-pyridyl)methylene-1,3-dithiolene) dianions. Reaction of the 1(2-) molybdenum dimer with pentacarbonylchlorothenium(i) affords a tetrametallic complex of formula [Mo2O2(μ-S)2(BPyDTS2)2{Re(CO)3Cl}2](2-) (2(2-)). The monomeric (CH3)2Sn(BPyDTS2) (3) tin complex has also been prepared for comparative purposes. In the structure of (Et4N)2[1], the two metal atoms are in a square pyramidal coordination environment defined by two bridging sulfur atoms, one terminal oxygen atom and the two sulfur atoms of the bifunctional dithiolene ligand. This arrangement leaves two nitrogen atoms on each side which coordinate to two Re atoms in the 2(2-) tetrametallic complex. Compound 3 has a distorted tetrahedral structure defined by two carbon atoms of the methyl groups and two sulfur atoms of the dithiolene ligand. The luminescence properties of all three complexes in acetonitrile have been investigated. Detailed studies supported on quantum mechanical calculations revealed that complex 1(2-) shows photoluminescence in the 600-800 nm region with a maximum wavelength of 628 nm and an emission quantum yield of 0.092, associated with an intraligand charge transfer (ILCT) transition. Coordination of two Re(CO)3Cl fragments to 1(2-) to afford 2(2-) does not affect the emission spectrum and shape although it decreases the quantum yield, approximately by a factor of 4.6. Compound 3 exhibits a similar emission spectrum to those of the complexes 1(2-) and 2(2-) in good agreement with the ILCT assignment. The quantum yield of 3 lies between that of the 1(2-) and 2(2-) complexes.

Synthesis and optical power limiting properties of heteroleptic Mo3S7 clusters

“…The UV-visible spectra of complexes 1-7 reveal intense bands at the highest energy (λ 1 , 304-342 nm), less intense bands at a lower energy (λ 2 , 335-427 nm), and weak bands at the lowest energy (λ 3 , 446-538 nm). The cluster (Et 4 N) 2 -[Mo 2 O 2 S 2 (BPyDTS 2 ) 2 ] is structurally distinct, 13 possessing an Mo 2 (µ 2 -S) 2 (O) 2 core, in contrast to the other heteroleptic complexes which possess Mo 3 (µ 3 -S)(µ 2 -S 2 ) 3 cores; its absorption maxima are at the lowest energy across the series of complexes presented in this work. For the latter, the lowest energy (λ 3 ) bands follow the wavelength order: complex 7 > complex 5 > complex 6 = complex 4 > complex 3 > complex 2 > complex 1, with the dmit (1,3-dithia-2-thione-4,5-dithiolate) ligated clusters 5-7 exhibiting the lowest energy maxima, and the chloroligated cluster 1 exhibiting the highest energy maximum.…”

“…The values of the excited-state cross-sections σ eff for the clusters are given in Table 1. With the exception of 13 and complexes 1-7…”

“…The optical power limiting properties of all these cluster complexes have been evaluated using the Z-scan technique. The NLO behavior of the previously reported dinuclear cluster ( 13 has also been investigated, with the aim of finding correlations between nuclearity and third-order optical functions.…”

“…[6][7][8][9][10][11][12][13][14][15][16][17][18] These trinuclear and tetranuclear complexes are all optical limiters (σeff > σ0) with threshold-limiting fluence decreasing on proceeding from tetranuclear to trinuclear, and from W-containing to Mo containing clusters. Power limiting has also been found in Mo3(µ3-S)(µ2-S)3 cluster sulfides derivatized with maleonitrile dithiolate, oxalate and thiocyanate ligands, although no clear tendencies could be drawn upon ligand substitution.…”

Heteroleptic Phenanthroline Complexes of Trinuclear Molybdenum Clusters with Luminescent Properties

“…We focused our attention on complexes 1 and 2, which are formed by the combination of molybdenum clusters and the ligand IPDOP. [36] Hence, the emission of the complexes is fully dominated by intraligand transitions. [14][15][16][24][25][26][27][28][29][30][31][32][33] Complexes 1 and 2 are the first reported combinations of an imidazophenanthroline ligand with a molybdenum cluster, and hence, they could open a new way of material design in any of the aforementioned areas.…”