B(C₆F₅)₃ Adducts of TCNE− and TCNQ−Vanadium Complexes as New Building Blocks for Molecule-Based Magnets

Abstract

The TCNX ligands TCNE and TCNQ reacted in toluene with Cp2V in the presence of B(C6F5)3 to yield, depending on the stoichiometry, the divanadium(III) complexes [(Cp2V)2{(C6F5)3B·(μ4-TCNX)·B(C6F5)3}] (X = Q (3), E (4)) or the vanadium(IV) dimers [Cp2V{(C6F5)3B·(μ4-TCNX)·B(C6F5)3}]2 (X = E (5), Q (6)), all containing [TCNX]2- ligands σ-bonded to vanadium through a nitrile nitrogen, as revealed by crystallographic (for 3−5) and magnetic studies (for 3−6).

Increasing the oxidation power of TCNQ by coordination of the fluorinated Lewis acid B(C6F5)3

“…Due to the 4:1 stoichiometry, all cyano groups are coordinated to the Lewis acidic boron centers. Consequently, no potential nitrogen donor sites are present, 29 resulting in a new, large weaklycoordinating monoanion with 60 fluorine atoms involved. To estimate the reduction potential that is needed to reduce the radical monoanions to diamagnetic dianions, we successfully used two equivalents of ferrocene per TCNQ.…”

Magnetic Coupling between Metal Spins through the 7,7,8,8‐Tetracyanoquinodimethane (TCNQ) Dianion

“…This series of compounds represent a third type of 3D [(M II ) 2 (TCNQ IIÀ ) 3 ] 2À coordination network that differs from the previously reported one, namely (Ph 3 PMe) 2 [Cd II 2 (TCNQ IIÀ ) 3 ] [6d] which crystallizes in the R-3 space group with one cation situated in the cavity, and the 3D [M II 2 -(TCNQ IIÀ ) 3 ] 2À (M = Mn, Zn, or Cd) coordination network with hexagonal channels. [6a] Several other compounds of the TCNQ 2À dianion have been previously reported and structurally characterized including a discrete complex with a syn-m 2 coordination binding mode to vanadocene, [11] a Mn(salen)-based 1D chain [12] and a 3D [Zn II (TCNQ IIÀ )bpy] framework. [7c] Thermogravimetric analyses indicate thermal stability up to approximately 250 8C, above which rapid decomposition occurs ( Figure S20 in the Supporting Information).…”

“…As was established by the structural and infrared data, the new family of compounds consist of 3D anionic frameworks of TCNQ dianions bridging divalent transition metal ions with large cavities filled with two (Ph 3 PMe) + cations resulting in an overall neutral compound of general formula (Ph 2 -(TCNQ IIÀ ) 3 ] 2À (M = Mn, Zn, or Cd) coordination network with hexagonal channels. [6a] Several other compounds of the TCNQ 2À dianion have been previously reported and structurally characterized including a discrete complex with a syn-m 2 coordination binding mode to vanadocene, [11] a Mn(salen)-based 1D chain [12] and a 3D [Zn II (TCNQ IIÀ )bpy] framework. [7c] Thermogravimetric analyses indicate thermal stability up to approximately 250 8C, above which rapid decomposition occurs (Figure S20 in the Supporting Information).…”

Boron, aluminium, gallium, indium and thallium

“…69 The tetracyano molecules ligands TCNE (tetracyanoethylene) and TCNQ (7,7,8,8-tetracyano-p-quinodimethane) reacted in toluene with Cp 2 V in the presence of B(C 6 F 5 ) 3 to yield the di-vanadium(III) complexes [(Cp 2 V) 2 {(C 6 F 5 ) 3 B Á (m 4 -TCNX) Á B(C 6 F 5 ) 3 }] (X = Q or E) or the vanadium(IV) dimers [Cp 2 -V{(C 6 F 5 ) 3 B Á (m 4 -TCNX) Á B(C 6 F 5 ) 3 }] 2 (X = E or Q), depending on the stoichiometry. 70 Green et al have described the synthesis of B(C 6 F 5 ) 3 -metal acyl adducts. The transition metal acyl compounds Co(L)(CO) 3 (COMe) (L = PMe 3 , PPhMe 2 , P(4-MeC 6 H 4 ) 3 , PPh 3 , and P(4-FC 6 H 4 ) 3 ), Mn(CO) 5 (COMe) and Mn(Z 5 -C 5 H 5 )(CO) 2 -(COMe) react with B(C 6 F 5 ) 3 to form the corresponding acyl coordinated adducts.…”