Zero-valent, oxidized, and mixed oxidation state chromium, molybdenum, and tungsten aryldiisocyanide polymers

Self-Assembled Mono- and Multilayers on Gold from 1,4-Diisocyanobenzene and Ruthenium Phthalocyanine

“…The isocyanide stretching band at 2122 cm -1 was attributed to the “free” isocyanide group pointing out from the surface. Upon axial complexation of RuPc by some of those free isocyanide groups, the stretching vibration of the isocyanide bond is expected to shift, as already observed with numerous organometallic complexes. − …”

“…Indeed, the effect of metal complexation on the stretching frequency of the isocyanide bond has already been well documented. The balance between σ-accepting and π-donating abilities of the metallic ions mainly accounts for the location of the νN⋮C stretching band: hypsochromic shifts from the pure 1,4-diisocyanobenzene spectrum have been reported when the σ-accepting character of the metallic ion is dominating the N⋮C to metal bonding, as in gold(I) complexes, but bathochromic shifts are more often observed since N⋮C to metal bonding is generally dominated by the π-back-bonding from the metallic ion to the isocyanide group, as in Rh(I), W(0), W(II) or Ru(II) complexes. ,,,, In the particular case of ruthenium phthalocyanines, a 35 to 40 cm -1 bathochromic shift has been reported upon axial complexation with 1,4-diisocyanobenzene, indicating that π-back-bonding from the ruthenium ion to the isocyanide group is strong …”

“…Very few examples of conjugated bis(isocyanide) molecules bound to two different metal centers can be found in the literature, all involving tungsten complexes. ,, The two latter references are devoted to 1,4-diisocyanobenzene-W(0) polymers, which are partially oxidized with iodine. The resulting mixed valence polymers exhibit both νN⋮C stretching bands arising from the tungsten(0) and the tungsten(II) complexes.…”

Coordinate Covalent Cobalt-Diisocyanide Multilayer Thin Films Grown One Molecular Layer at a Time

“…Isocyanides are known to bind a very wide range of metal centers − due to the ligand's ability to form stable sigma bonds with high-valent metal centers and to accept electrons into vacant π*-orbitals to form π-bonds with low-valent metal centers. ,,− Jaffe and co-workers have done extensive work on a number of two- and three-dimensional polymeric materials based on metal-isocyanide chemistry − including materials with Cr, Mo, W, Ir, Pt, Pd, Cu, and Rh-diisocyanides. These materials utilize the strong coordinate-covalent bonds of metal-isocyanides to build stable, easily prepared, bulk materials, demonstrating the feasibility of our approach to multilayered films using these components.…”

Crystalline Coordination Networks of Zero-Valent Metal Centers: Formation of a 3-Dimensional Ni(0) Framework with m-Terphenyl Diisocyanides

“…Permanently porous metal–organic materials have become prominent candidates for a number of targeted applications as a result of their high degree of synthetic flexibilty. , In particular, the ever-growing library of ligands and nodal geometries afforded by single-metal and higher nuclearity nodes presents a seemingly endless array of tunable multidimensional structures. − With regards to nodal types, molecular inorganic complexes have provided much of the inspiration for the preparation of numerous coordination polymers . However, despite the vast number of low-valent transition metal complexes that have been reported in the literature there are, to our knowledge, no such constructs that have been organized into a well-defined supramolecular network. − This has prevented an analysis of the properties that low-valent species, especially those in zero or negative formal oxidation states, may endow when used as the junction of framework materials. Accordingly, in an extension of our work on coordination frameworks derived from m -terphenyl diisocyanide ligands and four-coordinate Cu­(I) nodes, we now report the formation and physical properties of a valence isoelectronic network material incorporating four-coordinate Ni(0) centers as structural sites.…”