title: Structural classification of metal complexes with three-coordinate centres.
abstract: Attempts to describe the geometry about three-coordinate silver(i) complexes have proven difficult because interatomic angles generally vary wildly and there is no adequate or readily available classification system found in the literature. A search of the Cambridge Structural Database shows that complexes formed between any metal centre and three non-metal donors (18 001 examples) usually adopt geometries that are quite different than ideal 'textbook' extremes of either trigonal planar (~4% with α = β = γ = 120 ± 2°), T-shaped (~0.05% with α = 180 ± 2°, β = γ = 90 ± 2°), or trigonal pyramidal (~0.3% with α = β = γ = 110 ± 2°). Moreover, there are multiple variations of "Y-type" and "other" shapes that require elaboration. Thus, to assist in future structural descriptions, we developed a classification system that spans all known and yet-to-be-discovered three-coordinate geometries. A spreadsheet has also been constructed that utilizes the "shape-space" approach to extract the structural description from a user input of three angles about a tri-coordinate centre and the number of atoms in a plane. The structures of two silver(i) complexes of new N-donor ligands p-NH2C6H4C6H4CH(pz = pyrazol-1-yl)2, L1, and 2-ferrocenyl-4,5-di(2-pyridyl)imidazole, L2, illustrate the utility of this classification system.
authors.affiliation: Department of Chemistry, Winston-Salem State University, Winston-Salem, NC 27110-0003, USA. brownkj@wssu.edu.
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Davis
authors.forename: Joshua L
authors.initials: JL
authors.lastname: Watts
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Brown
authors.forename: Jeewantha S
authors.initials: JS
authors.lastname: Hewage
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Treleven
authors.forename: Sergey V
authors.initials: SV
authors.lastname: Lindeman
authors.forename: James R
authors.initials: JR
authors.lastname: Gardinier