title: Electrochemically directed synthesis of Cu2(I)(TCNQF4(II-))(MeCN)2 (TCNQF4 = 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane): voltammetry, simulations, bulk electrolysis, spectroscopy, photoactivity, and X-ray crystal structure of the Cu2(I)(TCNQF4(II-))(EtCN)2 analogue.
abstract: The new compound Cu2(I)(TCNQF4(II-))(MeCN)2 (TCNQF4(2-) = dianion of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane) has been synthesized by electrochemically directed synthesis involving reduction of TCNQF4 to TCNQF4(2-) in acetonitrile containing [Cu(MeCN)4](+)(MeCN) and 0.1 M Bu4NPF6. In one scenario, TCNQF4(2-) is quantitatively formed by reductive electrolysis of TCNQF4 followed by addition of [Cu(MeCN)4](+) to form the Cu2(I)(TCNQF4(II-))(MeCN)2 coordination polymer. In a second scenario, TCNQF4 is reduced in situ at the electrode surface to TCNQF4(2-), followed by reaction with the [Cu(MeCN)4](+) present in the solution, to electrocrystallize Cu2(I)(TCNQF4(II-))(MeCN)2. Two distinct phases of Cu2(I)(TCNQF4(II-))(MeCN)2 are formed in this scenario; the kinetically favored form being rapidly converted to the thermodynamically favored Cu2(I)(TCNQF4(II-))(MeCN)2. The postulated mechanism is supported by simulations. The known compound Cu(I)TCNQF4(I-) also has been isolated by one electron reduction of TCNQF4 and reaction with [Cu(MeCN)4](+). The solubility of both TCNQF4(2-)- and TCNQF4(•-)-derived solids indicates that the higher solubility of Cu(I)TCNQF4(I-) prevents its precipitation, and thus Cu2(I)(TCNQF4(II-))(MeCN)2 is formed. UV-visible and vibrational spectroscopies were used to characterize the materials. Cu2(I)(TCNQF4(II-))(MeCN)2 can be photochemically transformed to Cu(I)TCNQF4(I-) and Cu(0). Scanning electron microscopy images reveal that Cu(I)TCNQF4(I-) and Cu2(I)(TCNQF4(II-))(MeCN)2 are electrocrystallized with distinctly different morphologies. Thermogravimetric and elemental analysis data confirm the presence of CH3CN, and single-crystal X-ray diffraction data for the Cu2(I)(TCNQF4(II-))(EtCN)2 analogue shows that this compound is structurally related to Cu2(I)(TCNQF4(II-))(MeCN)2.
authors.affiliation: School of Chemistry, Monash University , Clayton, Victoria 3800, Australia.
authors.forename: Thanh H
authors.initials: TH
authors.lastname: Le
authors.forename: Ayman
authors.initials: A
authors.lastname: Nafady
authors.forename: Nguyen T
authors.initials: NT
authors.lastname: Vo
authors.forename: Robert W
authors.initials: RW
authors.lastname: Elliott
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Hudson
authors.forename: Richard
authors.initials: R
authors.lastname: Robson
authors.forename: Brendan F
authors.initials: BF
authors.lastname: Abrahams
authors.forename: Lisandra L
authors.initials: LL
authors.lastname: Martin
authors.forename: Alan M
authors.initials: AM
authors.lastname: Bond