From chromium-chromium quintuple bonds to molecular squares and porous coordination polymers.

Reaction of the quintuply bonded chromium(I) dimer [ApCrCrAp] (Ap = sterically demanding 2-aminopyridinate) with pyrazine yields a chromium(II) complex with a η(4):η(4) face-on coordinated pyrazine dianion. Reaction with 4,4'-bipyridine, on the other hand, completely cleaves the metal-metal bond, leading to a chromium(II)-based molecular square. XRD and magnetic measurements show ligand radical anions and a ferrimagnetic alignment of alternating metal and ligand magnetic moments.

Quintuple bond reactivity toward group 16 and 17 elements: addition vs insertion.

The low valent, coordinatively unsaturated, and formally quintuply bonded bimetallic aminopyridinato chromium complex 1 was investigated regarding its reactivity toward group 16 and 17 elements. Reaction of 1 with O(2) yielded a dimeric Cr oxo complex 2, a compound with a high formal oxidation state carrying both bridging and terminal oxo ligands. Reactions with the higher homologues of the group lead to the formation of dimeric Cr(II) complexes in which E(2)(2-) ligands were formed [E = S (3), Se (4), and Te (5)].