catalysis – Chemical Crystallography

Presented by: Dr. Andrew D. Schwarz & Liban M. A. Saleh
Research Leader: Prof. Philip Mountford & Prof. Simon Aldridge
Published: Journal of the American Chemical Society

Transition-metal boryl compounds (L)M(BX₂)_x, containing 2‑center, 2‑electron σ‑bonds have been a topic of outstanding interest due to pivotal roles in a variety of catalytic and stoichiometric transformations, e.g. hydroboration and diboration of C–C π-bonds, and functionalization of alkane and arene C‑H bonds. To date, virtually all boryl complexes have been prepared either by B‑X (X = H or halogen) or B‑B oxidative addition to a low oxidation state (L)M species, or by nucleophilic attack of a [(L)M]‑ anion on a XBR₂ or related source of the boryl moiety. However, utilisation of the nucleophilic Li{B(NArCH)₂}(THF)₂ (Ar = 2,6‑C₆H₃ⁱPr₂), allows access to rare earth metal boryl compounds. Data were collected on a small colourless crystal (0.05 × 0.05 × 0.05 mm) using the new Oxford Diffraction (Agilent) SuperNova diffractometers and copper radiation.

Structure of the Month – February 2011

Presented by: Dr. Adrian B. Chaplin
Research Leader: Prof. Andrew S. Weller
Published: Journal of the American Chemical Society

Making and breaking C–C bonds in the solid state: The structure of [Ir(BINOR‑S)(PiPr₃)][BAr^F₄] over the temperature range 100–250 K reveals a dynamic equilibrium between Ir(III) C–C agostic and Ir(V) bis-alkyl tautomers in the solid-state. The solid-state dynamic behaviour is shown in the reaction scheme (a), with populations determined using X-ray diffraction (b) and the Van’t Hoff plot for this process (c, R2(fit) = 0.999).The disordered model at 150 K containing (d) Ir(III) and (e) Ir(V). The combined model and thermal ellipsoid plot of the structure refined without cation disorder modelling are also shown (f & g respectively).

Structure of the Month – December 2010