Single-component molecular metals with extended-TTF dithiolate ligands.

Optical properties of small inorganic and organic metal particles

The structures of three linear-chain platinum(II) diimine complexes have been determined [Pt···Pt, A]:  Pt(bpm)Cl_2·0.5(nmp) (3) [3.411(1), 3.371(1)], Pt(phen)(CN)_2 (6) [3.338(1), 3.332(1)], and Pt(bpy)(NCS)_2 (7) [3.299(2)] (bpm = 2,2‘-bipyrimidine, phen = 1,10-phenanthroline, bpy = 2,2‘-bipyridine, nmp = 1-methyl-2-pyrrolidinone). The Pt···Pt distances in these and in seven related compounds range from 3.24 to 3.49 A. While we find evidence of interligand interactions influencing these structures, the Pt···Pt bonds are the most important of the stacking forces. The metal−metal distances are generally consistent with an electronic structural model in which σ-donor/π-acceptor ligands strengthen Pt···Pt bonding interactions (for example, the Pt···Pt distances in 3 are 0.04 and 0.08 A shorter than in the bpy analogue). We have also found that the yellow form of Pt(dmbpy)(NCO)_2 (1b) (4,4‘-dimethyl-2,2‘-bipyridine) has a columnar structure; however, in contrast to the linear-chain form (1), which is orange, the Pt atoms are well separated (>4.9 A). Interestingly, the yellow form is 7% denser than the orange form; this result is consistent with the concept that directed intermolecular interactions give rise to lower density polymorphs. Crystal data:  (3) monoclinic, C2/m (No. 12), a = 12.668(4) A, b = 15.618(6) A, c = 6.704(3) A, β = 93.43(3)°, Z = 4; (6) orthorhombic, Pbca (No. 61), a = 38.731(13) A, b = 18.569(3) A, c = 6.628(1) A, Z = 16; (7) orthorhombic, Pbcm (No. 57), a = 10.349(3) A, b = 19.927(5) A, c = 6.572(3) A, Z = 4; (1b) monoclinic, C2/c (No. 15), a = 17.313(4) A, b = 12.263(3) A, c = 14.291(4) A, β = 114.00(2)°, Z = 8.

Linear-Chain Structures of Platinum(II) Diimine Complexes

Theoretical studies in palladium and platinum molecular chemistry.

The design, synthesis, and study of electrically conductive molecular and polymeric substances constitute a new scientific endeavor involving the interaction of chemists, physicists, and materials scientists. The strategies, developments, and challenges in these two closely related fields are analyzed via a class of materials that bridges both: assemblies of electrically conductive metallomacrocycles. It is seen that efforts to rationally synthesize tailored, "metal-like" molecular arrays lead logically to structure-enforced polymeric assemblies of linked molecular subunits such as metallophthalocyanines. The properties of these assemblies and fragments thereof provide information on the relationship between atomic-level local architecture, electronic structure, and macroscopic transport properties. Electrcally conductive, processable polymeric materals also follow from these results.

https://science.sciencemag.org/content/sci/227/4689/881.full.pdf

Electrically Conductive Metallomacrocyclic Assemblies

Planar complexes, and particularly those of platinum, can form structures containing linear chains of heavy metal atoms with metal-metal distances as short as 3.1 A. The bonding in these chains can be strengthened by partial oxidation, and the bond lengths can be reduced to 2.8 A in this way. Model structures for the novel nonstoichiometric products, such as K2[Pt(CN)4]Cl0·32 · 2.6 H2O, are considered. The bonding is also discussed on the basis of a one-dimensional band model.

K. Krogmann

Papers

Planar Complexes Containing Metal‐Metal Bonds