Synthesis, structures and properties of bis(carbodiimido) complexes of Ni(ii), Pd(ii) and Pt(ii)

Azide Chemistry – An Inorganic Perspective, Part II[‡][3+2]‐Cycloaddition Reactions of Metal Azides and Related Systems

“…Table 7). [49] This compares well with cis-[M{CN 4 Ph} 2 (CNPh)PPh 3 ], a product from our early experiments with M(N 3 ) 2 (PPh 3 ) 2 (M = Pd, Pt) and phenylisocyanide which shows no sign of turning into a carbodiimido complex.…”

“…Certainly, the role of the ancillary ligands also needed to be considered; so a series of particularly spacefilling phosphines and diphosphines was tested in support of the steric bulk of the 2,6-dimethylphenyl substituent on the tetrazole ring, which was suspected to exert an influence facilitating N 2 elimination from the tetrazolato ligand forcing the formation of the space-saving carbodiimide group. [49,50,505] The exact opposite happened, however. All azido palladium and platinum complexes containing the bulky chelating bis(phosphine) co-ligands 1,1'-bis(diphenylphos-phanyl)ferrocene (dppf) or 1,8-bis(diphenylphosphanyl)-naphthalene (dppn) underwent [3+2]-cycloaddition with both, alkyl (CNR, R = Cy, Bu t ) and arylisocyanides (CN-2,6-Me 2 C 6 H 3 ) converting the azido ligands into five-membered, C-coordinated tetrazolate rings exclusively, in spite of the steric congestion in the ligand sphere ("that might suppress cycloaddition reactivity").…”

“…[49,51] In those asymmetric mixed-ligand complexes of which structure 97 represents a rather spectacular example, the electronic requirements of the various bonding participants seem to be best balanced out. [54] Repeated attempts to explain the observed reactivities by steric effects caused confusion and eventually proved untenable.…”

“…Kim and co-workers in a series of papers dealing with group 10 transition metals and, in particular, with palladium. [46,47,[49][50][51]53,54,57,[60][61][62]64] The chemical reaction finally arriving at carbodiimide type products has usually been monitored by the disappearance of the antisymmetric stretching band of the N 3 group at ca. [46,47,[49][50][51]53,54,57,[60][61][62]64] All along the line this novel ligand appears as the result of a consecutive (stepwise) reaction -forced or spontaneous -of the primary C-heterocycle which proceeds with loss of N 2 and CǞN-migration of the metal (Scheme 22).…”

Synthesis and structure of novel benzisothiazole-tetrazolyl derivatives for potential application as nitrogen ligands

“…Indeed, it has been shown that the tetrazole ligand is able to participate in at least seven distinct types of coordination modes with metal ions, in the construction of novel metal-organic frameworks. Furthermore, numerous tetrazolyl ligands, coordinated with different metal centres, such as nickel, ruthenium, palladium or platinum, have been tested in catalyzed reactions [18][19][20].…”