“…Complexes with chalcogenide ligands include divanadium and polyvanadium clusters as well as oxovanadium complexes having monochalcogen and dichalcogen ligands. Structures 06 , 07 , and 08 (Herberhold et al, Bolinger et al) have long V–V distances (3.11 to 3.29 Å) which may not indicate metal–metal covalent interactions. Complexes 09 to 14 have significantly shorter R MM values of 2.510 to 2.74 Å, which are more typical of V–V covalent bonds (Bolinger et al, Rheingold, , Bose et al , ).…”
This survey of metal–metal
(MM) bond distances in binuclear
complexes of the first row 3d-block elements reviews experimental
and computational research on a wide range of such systems. The metals
surveyed are titanium, vanadium, chromium, manganese, iron, cobalt,
nickel, copper, and zinc, representing the only comprehensive presentation
of such results to date. Factors impacting MM bond lengths that are
discussed here include (a) the formal MM bond order, (b) size of the
metal ion present in the bimetallic core (M2)
n+, (c) the metal oxidation state, (d) effects of
ligand basicity, coordination mode and number, and (e) steric effects
of bulky ligands. Correlations between experimental and computational
findings are examined wherever possible, often yielding good agreement
for MM bond lengths. The formal bond order provides a key basis for
assessing experimental and computationally derived MM bond lengths.
The effects of change in the metal upon MM bond length ranges in binuclear
complexes suggest trends for single, double, triple, and quadruple
MM bonds which are related to the available information on metal atomic
radii. It emerges that while specific factors for a limited range
of complexes are found to have their expected impact in many cases,
the assessment of the net effect of these factors is challenging.
The combination of experimental and computational results leads us
to propose for the first time the ranges and “best”
estimates for MM bond distances of all types (Ti–Ti through
Zn–Zn, single through quintuple).
“…Complexes with chalcogenide ligands include divanadium and polyvanadium clusters as well as oxovanadium complexes having monochalcogen and dichalcogen ligands. Structures 06 , 07 , and 08 (Herberhold et al, Bolinger et al) have long V–V distances (3.11 to 3.29 Å) which may not indicate metal–metal covalent interactions. Complexes 09 to 14 have significantly shorter R MM values of 2.510 to 2.74 Å, which are more typical of V–V covalent bonds (Bolinger et al, Rheingold, , Bose et al , ).…”
This survey of metal–metal
(MM) bond distances in binuclear
complexes of the first row 3d-block elements reviews experimental
and computational research on a wide range of such systems. The metals
surveyed are titanium, vanadium, chromium, manganese, iron, cobalt,
nickel, copper, and zinc, representing the only comprehensive presentation
of such results to date. Factors impacting MM bond lengths that are
discussed here include (a) the formal MM bond order, (b) size of the
metal ion present in the bimetallic core (M2)
n+, (c) the metal oxidation state, (d) effects of
ligand basicity, coordination mode and number, and (e) steric effects
of bulky ligands. Correlations between experimental and computational
findings are examined wherever possible, often yielding good agreement
for MM bond lengths. The formal bond order provides a key basis for
assessing experimental and computationally derived MM bond lengths.
The effects of change in the metal upon MM bond length ranges in binuclear
complexes suggest trends for single, double, triple, and quadruple
MM bonds which are related to the available information on metal atomic
radii. It emerges that while specific factors for a limited range
of complexes are found to have their expected impact in many cases,
the assessment of the net effect of these factors is challenging.
The combination of experimental and computational results leads us
to propose for the first time the ranges and “best”
estimates for MM bond distances of all types (Ti–Ti through
Zn–Zn, single through quintuple).
“…The properties of TCNQ-based molecular materials (TCNQ = 7,7,8,8-tetracyanoquinodimethane, structure 1) such as charge-transfer salts, organometallic compounds, and coordination polymers have generated a great deal of interest over the past four decades, − particularly with respect to their use in storage and light emitting devices, catalysis, and sensing applications. − …”
The chemically reversible solid−solid phase transformation of a TCNQ-modified glassy carbon, indium
tin oxide, or metal electrode into Co[TCNQ]2(H2O)2 material in the presence of Co2+
(aq) containing
electrolytes has been induced and monitored electrochemically. Voltammetric data reveal that the TCNQ/Co[TCNQ]2(H2O)2 interconversion process is independent of electrode material and identity of cobalt
electrolyte anion. However, a marked dependence on electrolyte concentration, scan rate, and method of
electrode modification (drop casting or mechanical attachment) is found. Cyclic voltammetric and double
potential step chronoamperometric measurements confirm that formation of Co[TCNQ]2(H2O)2 occurs
through a rate-determining nucleation and growth process that initially involves incorporation of Co2+
(aq)
ions into the reduced TCNQ crystal lattice at the TCNQ|electrode|electrolyte interface. Similarly, the
reverse (oxidation) process, which involves transformation of solid Co[TCNQ]2(H2O)2 back to parent
TCNQ crystals, also is controlled by nucleation−growth kinetics. The overall chemically reversible process
that represents this transformation is described by the reaction: 2TCNQ0
(s) + 2e- + Co2+
(aq) + 2H2O ⇌
[Co(TCNQ)2(H2O)2](s). Ex situ SEM images illustrated that this reversible TCNQ/Co[TCNQ]2(H2O)2
conversion process is accompanied by drastic size and morphology changes in the parent solid TCNQ.
In addition, different sizes of needle-shaped nanorod/nanowire crystals of Co[TCNQ]2(H2O)2 are formed
depending on the method of surface immobilization.
“…13 Moreover, the N1s orbital appeared as a single feature at 398.7 eV, indicating one type of TCNQ in the nal products. 18,19 TGA data of the products suggested that the compound lost its $7% mass at temperatures below 225 C, which corresponded to the molecular weight of two water molecules. When the temperature was over 225 C, a large mass loss occurred due to the decomposition of the products via the loss of TCNQ.…”
Metal-organic charge-transfer complexes based on 7,7,8,8-tetracyanoquinodimethane (TCNQ) have received considerable attention because of their unique solid-state physical properties for potential applications in nanoscale opto-electronic devices. To address the challenge in preparing novel metal-TCNQ (MTCNQ) nanostructures, here we introduce a facile and efficient way for synthesizing MTCNQ, taking Ni[TCNQ]2(H2O)2 as an example. By finely tuning the amount of water added into TCNQ solution, well-ordered and large-scale patterns of Ni[TCNQ]2(H2O)2 were successfully obtained in a controllable manner. This facile method will not only be beneficial for the tailored preparation of nanoscale MTCNQ complexes, but also enrich the chemistry of TCNQ.
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