Some highlights from the development and use of bulky monodentate ligands

Synthesis and characterization of new, modified terphenyl ligands: Increasing the rotational barrier for flanking rings

“…The product was analyzed by 1 H and 13 C NMR. 1 According to the general procedure described in Section 5, 1 was obtained as a white, microcrystalline powder. Large, colorless crystals, suitable for X-ray crystallography, were isolated after the initial microcrystalline material was dissolved in ether and stored for 3 days in a ca.…”

“…Yield 55%. 1 To a solution of 2.62 g (5 mmol) of 3 in 40 mL hexane, 3.2 mL 1.6 M Bu n Li solution was added slowly via syringe at 0°C. After ca.…”

“…Sterically crowding ligands have been used with remarkable success in inorganic and organometallic chemistry over the past three decades [1]. They have allowed the first syntheses of molecules featuring previously unknown bonding types, geometries, electron configurations or oxidation states.…”

On the Borderline between cis and trans in Organometallic(Phosphane)platinum(II) Complexes

“…[2,[7][8][9] Besides their numerous applications in organometallic catalysis, they have been found to be ideally suited for the determination of their configurations or configurational equilibria since the 31 P- 195 Pt coupling constants are very sensitive to the trans and cis influence of further co-ligands. [10,11] Aryl ligands can be used to probe the subtle interplay of steric and electronic factors of the configuration since they are (i) strongly donating ligands; (ii) their electronic properties can be tuned by various substituents and the observed changes can be easily rationalised in terms of inductive or mesomeric influences; (iii) they can be easily introduced by established metathesis reactions; [9] (iv) their steric demand can be varied almost deliberately; [12] and (v) since their ring planes are usually oriented almost perpendicular with respect to the binding plane they allow discrimination of the two hemispheres above and below the binding plane, for example by unsymmetrical aryl ligands like 2-R,6-RЈ-C 6 H 4 that give rise to further isomerism. [13] We therefore decided to prepare a series of (triethylphosphane)platinum complexes [Pt(Ar) 2 (PEt 3 ) 2 ] [Ar = 2,4,6-trimethylphenyl (Mes), 2,6-dimethylphenyl (Xyl), 2-methylphenyl (2-Tol), 3-methylphenyl (3-Tol), 4-methylphenyl (4-Tol) and phenyl (Ph)] with various alkyl substitution patterns on the aryl ligands.…”

Ligand Association/Dissociation Paths and Ill‐Defined Coordination Numbers

“…[9] The appreciation of the role that such secondary interactions may have led a group of researchers to say that a family of dithiolene copper complexes is "blessed with secondary coordination ability." [8] Other ways of referring to imprecise coordination numbers in transition-metal chemistry include the naming of some copper(I) complexes as "quasi-two-coordinate" to allude to the weak bonding of additional ligands, [10] or the use of the expression "semi-coordinating interaction," [11] not to mention the widely recognized "agostic interactions" or secondary coordination of ancillary groups [12] that may help, for example, stabilize low coordination numbers [13] or less common coordination geometries, such as a T-shaped tricoordination [14] or a seesaw tetracoordination. [15] Among the variety of examples that can be found in the literature, we choose to mention in more detail here only some illustrative ones.…”