Transition‐Metal Complexes Featuring Z‐Type Ligands: Agreement or Discrepancy between Geometry and dⁿ Configuration?

Abstract

The seminal formalism ML l X x (M = transition metal, L = 2e-donor ligand, X = 1e-donor ligand) provides a unified description for transition-metal complexes. Besides the wellknown L-and X-type ligands, the ability of Lewis acids to act as zero-electron donors/two-electron acceptors was recognized early on, [1] and these ligands were referred to as Z-type ligands in ML l

Toward a comprehensive definition of oxidation state (IUPAC Technical Report)

“…1; Au populates the Au-B bonding MO) and including in d n all antibonding, nonbonding, and weakly bonding orbitals of Au (its bond to B). Bourissou's [149] Mössbauer spectrum of the exactly these n electrons (d 10 ) and OS Au = +1 is suggested in compliance with eq. 6, even though the squareplanar coordination implies Au +3 with d 8 since the donated Au pair became the Au-B bond itself (Fig.…”

“…A telling example is the Au-B bond in the [Au{B(PC 6 H 4 ) 2 (C 6 H 5 )}Cl] complex synthesized by Bourissou's group [149], featuring B as the LA ligand of higher Allen EN. In Fig.…”

“…Left: supported, with octahedrally coordinated Ru [321]. Right: supported, with square-planar Au [149].…”

“…6 and n − 2 = 6 complies with the square-pyramidal coordination geometry. Similarly, in the square planar [{κ 3 -(o-(iPr 2 P)C 6 H 4 ) 2 B(C 6 H 5 )}AuCl] [149], gold would be denoted as Au(I, n = 10 in d n−2 ) where n = 10 corresponds to the generic OS Au = +1, also seen by Mössbauer spectroscopy, whereas n − 2 = 8 to the square-planar Au coordination. Braunschweig [331].…”

Coordination Chemistry of Neutral (Ln)–Z Amphoteric and Ambiphilic Ligands

“…Compound 15, synthesized from precursor AuCl(SMe 2 ), has a square-planar geometry, which is confirmed by the fact that the sum of the angles around Au is approximately 360°(ΣAu α = 362.2°for R = iPr and 364.2°for R = Ph). [30] In addition to the coordination of two phosphanes from the ambiphilic ligand to the metal centre, one AuǞB dative interaction is observed [Au-B = 2.309(8) Å for R = iPr and 2.335(5) Å for R = Ph]. A more detailed analysis on the nature of the MǞB interaction in this complex will be discussed in a further section.…”