Monoanionic molybdenum and tungsten tris(dithiolene) complexes: A multifrequency EPR study

Stephen Sproules; Priyabrata Banerjee; Thomas Weyhermüller; Yong Yan; James P. Donahue; Karl Wieghardt

doi:10.1021/ic2006265

Monoanionic molybdenum and tungsten tris(dithiolene) complexes: A multifrequency EPR study

Stephen Sproules
, Priyabrata Banerjee
, Thomas Weyhermüller
, Yong Yan
, James P. Donahue
, Karl Wieghardt

Research output: Contribution to journal › Article › peer-review

58 Scopus citations

Abstract

Numerous Mo and W tris(dithiolene) complexes in varying redox states have been prepared and representative examples characterized crystallographically: [M(S ₂C ₂R ₂) ₃] ^z [M = Mo, R = Ph, z = 0 (1) or 1- (2); M = W, R = Ph, z = 0 (4) or 1- (5); R = CN, z = 2-, M = Mo (3) or W (6)]. Changes in dithiolene C-S and C-C bond lengths for 1 versus 2 and 4 versus 5 are indicative of ligand reduction. Trigonal twist angles (Θ) and dithiolene fold angles (α) increase and decrease, respectively, for 2 versus 1, 5 versus 4. Cyclic voltammetry reveals generally two reversible couples corresponding to 0/1- and 1-/2- reductions. The electronic structures of monoanionic molybdenum tris(dithiolene) complexes have been analyzed by multifrequency (S-, X-, Q-band) EPR spectroscopy. Spin-Hamiltonian parameters afforded by spectral simulation for each complex demonstrate the existence of two distinctive electronic structure types. The first is [Mo ^IV( ^AL ₃ ^5-•)] ^1- ( ^AL = olefinic dithiolene, type A), which has the unpaired electron restricted to the tris(dithiolene) unit and is characterized by isotropic g-values and small molybdenum superhyperfine coupling. The second is formulated as [Mo ^V( ^BL ₃ ^6-)] ^1- ( ^BL = aromatic dithiolene, type B) with spectra distinguished by a prominent g-anisotropy and hyperfine coupling consistent with the (dz ²) ¹ paramagnet. The electronic structure disparity is also manifested in their electronic absorption spectra. The compound [W(bdt) ₃] ^1- exhibits spin-Hamiltonian parameters similar to those of [Mo(bdt) ₃] ^1- and thus is formulated as [W ^V( ^BL ₃ ^6-)] ^1-. The EPR spectra of [W( ^AL ₃)] ^1- display spin-Hamiltonian parameters that suggest their electronic structure is best represented by two resonance forms {[W ^IV( ^AL ₃ ^5-•)] ^1- ↔ [W ^V( ^AL ₃ ^6-)] ^1-}. The contrast with the corresponding [Mo ^IV( ^AL ₃ ^5-•)] ^1- complexes highlights tungsten's preference for higher oxidation states.

Original language	English (US)
Pages (from-to)	7106-7122
Number of pages	17
Journal	Inorganic Chemistry
Volume	50
Issue number	15
DOIs	https://doi.org/10.1021/ic2006265
State	Published - Aug 1 2011
Externally published	Yes

All Science Journal Classification (ASJC) codes

Physical and Theoretical Chemistry
Inorganic Chemistry

Access to Document

10.1021/ic2006265

Cite this

@article{8280822dec934ab398289654e1d9d74a,

title = "Monoanionic molybdenum and tungsten tris(dithiolene) complexes: A multifrequency EPR study",

abstract = "Numerous Mo and W tris(dithiolene) complexes in varying redox states have been prepared and representative examples characterized crystallographically: [M(S 2C 2R 2) 3] z [M = Mo, R = Ph, z = 0 (1) or 1- (2); M = W, R = Ph, z = 0 (4) or 1- (5); R = CN, z = 2-, M = Mo (3) or W (6)]. Changes in dithiolene C-S and C-C bond lengths for 1 versus 2 and 4 versus 5 are indicative of ligand reduction. Trigonal twist angles (Θ) and dithiolene fold angles (α) increase and decrease, respectively, for 2 versus 1, 5 versus 4. Cyclic voltammetry reveals generally two reversible couples corresponding to 0/1- and 1-/2- reductions. The electronic structures of monoanionic molybdenum tris(dithiolene) complexes have been analyzed by multifrequency (S-, X-, Q-band) EPR spectroscopy. Spin-Hamiltonian parameters afforded by spectral simulation for each complex demonstrate the existence of two distinctive electronic structure types. The first is [Mo IV( AL 3 5-•)] 1- ( AL = olefinic dithiolene, type A), which has the unpaired electron restricted to the tris(dithiolene) unit and is characterized by isotropic g-values and small molybdenum superhyperfine coupling. The second is formulated as [Mo V( BL 3 6-)] 1- ( BL = aromatic dithiolene, type B) with spectra distinguished by a prominent g-anisotropy and hyperfine coupling consistent with the (dz 2) 1 paramagnet. The electronic structure disparity is also manifested in their electronic absorption spectra. The compound [W(bdt) 3] 1- exhibits spin-Hamiltonian parameters similar to those of [Mo(bdt) 3] 1- and thus is formulated as [W V( BL 3 6-)] 1-. The EPR spectra of [W( AL 3)] 1- display spin-Hamiltonian parameters that suggest their electronic structure is best represented by two resonance forms \{[W IV( AL 3 5-•)] 1- ↔ [W V( AL 3 6-)] 1-\}. The contrast with the corresponding [Mo IV( AL 3 5-•)] 1- complexes highlights tungsten's preference for higher oxidation states.",

author = "Stephen Sproules and Priyabrata Banerjee and Thomas Weyherm{\"u}ller and Yong Yan and Donahue, \{James P.\} and Karl Wieghardt",

year = "2011",

month = aug,

day = "1",

doi = "10.1021/ic2006265",

language = "English (US)",

volume = "50",

pages = "7106--7122",

journal = "Inorganic Chemistry",

issn = "0020-1669",

publisher = "American Chemical Society",

number = "15",

}

TY - JOUR

T1 - Monoanionic molybdenum and tungsten tris(dithiolene) complexes

T2 - A multifrequency EPR study

AU - Sproules, Stephen

AU - Banerjee, Priyabrata

AU - Weyhermüller, Thomas

AU - Yan, Yong

AU - Donahue, James P.

AU - Wieghardt, Karl

PY - 2011/8/1

Y1 - 2011/8/1

N2 - Numerous Mo and W tris(dithiolene) complexes in varying redox states have been prepared and representative examples characterized crystallographically: [M(S 2C 2R 2) 3] z [M = Mo, R = Ph, z = 0 (1) or 1- (2); M = W, R = Ph, z = 0 (4) or 1- (5); R = CN, z = 2-, M = Mo (3) or W (6)]. Changes in dithiolene C-S and C-C bond lengths for 1 versus 2 and 4 versus 5 are indicative of ligand reduction. Trigonal twist angles (Θ) and dithiolene fold angles (α) increase and decrease, respectively, for 2 versus 1, 5 versus 4. Cyclic voltammetry reveals generally two reversible couples corresponding to 0/1- and 1-/2- reductions. The electronic structures of monoanionic molybdenum tris(dithiolene) complexes have been analyzed by multifrequency (S-, X-, Q-band) EPR spectroscopy. Spin-Hamiltonian parameters afforded by spectral simulation for each complex demonstrate the existence of two distinctive electronic structure types. The first is [Mo IV( AL 3 5-•)] 1- ( AL = olefinic dithiolene, type A), which has the unpaired electron restricted to the tris(dithiolene) unit and is characterized by isotropic g-values and small molybdenum superhyperfine coupling. The second is formulated as [Mo V( BL 3 6-)] 1- ( BL = aromatic dithiolene, type B) with spectra distinguished by a prominent g-anisotropy and hyperfine coupling consistent with the (dz 2) 1 paramagnet. The electronic structure disparity is also manifested in their electronic absorption spectra. The compound [W(bdt) 3] 1- exhibits spin-Hamiltonian parameters similar to those of [Mo(bdt) 3] 1- and thus is formulated as [W V( BL 3 6-)] 1-. The EPR spectra of [W( AL 3)] 1- display spin-Hamiltonian parameters that suggest their electronic structure is best represented by two resonance forms {[W IV( AL 3 5-•)] 1- ↔ [W V( AL 3 6-)] 1-}. The contrast with the corresponding [Mo IV( AL 3 5-•)] 1- complexes highlights tungsten's preference for higher oxidation states.

AB - Numerous Mo and W tris(dithiolene) complexes in varying redox states have been prepared and representative examples characterized crystallographically: [M(S 2C 2R 2) 3] z [M = Mo, R = Ph, z = 0 (1) or 1- (2); M = W, R = Ph, z = 0 (4) or 1- (5); R = CN, z = 2-, M = Mo (3) or W (6)]. Changes in dithiolene C-S and C-C bond lengths for 1 versus 2 and 4 versus 5 are indicative of ligand reduction. Trigonal twist angles (Θ) and dithiolene fold angles (α) increase and decrease, respectively, for 2 versus 1, 5 versus 4. Cyclic voltammetry reveals generally two reversible couples corresponding to 0/1- and 1-/2- reductions. The electronic structures of monoanionic molybdenum tris(dithiolene) complexes have been analyzed by multifrequency (S-, X-, Q-band) EPR spectroscopy. Spin-Hamiltonian parameters afforded by spectral simulation for each complex demonstrate the existence of two distinctive electronic structure types. The first is [Mo IV( AL 3 5-•)] 1- ( AL = olefinic dithiolene, type A), which has the unpaired electron restricted to the tris(dithiolene) unit and is characterized by isotropic g-values and small molybdenum superhyperfine coupling. The second is formulated as [Mo V( BL 3 6-)] 1- ( BL = aromatic dithiolene, type B) with spectra distinguished by a prominent g-anisotropy and hyperfine coupling consistent with the (dz 2) 1 paramagnet. The electronic structure disparity is also manifested in their electronic absorption spectra. The compound [W(bdt) 3] 1- exhibits spin-Hamiltonian parameters similar to those of [Mo(bdt) 3] 1- and thus is formulated as [W V( BL 3 6-)] 1-. The EPR spectra of [W( AL 3)] 1- display spin-Hamiltonian parameters that suggest their electronic structure is best represented by two resonance forms {[W IV( AL 3 5-•)] 1- ↔ [W V( AL 3 6-)] 1-}. The contrast with the corresponding [Mo IV( AL 3 5-•)] 1- complexes highlights tungsten's preference for higher oxidation states.

UR - https://www.scopus.com/pages/publications/79960775643

UR - https://www.scopus.com/pages/publications/79960775643#tab=citedBy

U2 - 10.1021/ic2006265

DO - 10.1021/ic2006265

M3 - Article

C2 - 21699192

AN - SCOPUS:79960775643

SN - 0020-1669

VL - 50

SP - 7106

EP - 7122

JO - Inorganic Chemistry

JF - Inorganic Chemistry

IS - 15

ER -

Monoanionic molybdenum and tungsten tris(dithiolene) complexes: A multifrequency EPR study

Abstract

All Science Journal Classification (ASJC) codes

Access to Document

Other files and links

Fingerprint

Cite this