Novel polypyrazolylborate ligands: coordination control through 3-substituents of the pyrazole ring

Molybdenum–tin and molybdenum–copper complexes derived from the molybdenum tricarbonyl anions, LMo(CO)3− (where L = HBpz3 or HBpz″3; pz = pyrazolyl, N2C3H3; and pz″ = 3,5-dimethylpyrazolyl, N2C5H7)

“…With the incorporation of the much more sterically demanding ligand HBpzU3-(cone angle -225" (7,9)) in the molybdenum tricarbonyl anion, ( H B p~"~) M o ( c o )~-, it was anticipated that a crowded Mo centre might lead to different reactivity patterns. Precedents in the literature include the extensive chemistry of the (HBpzU3) Mo(N0) (X)Z (X = halogen), complexes (1 2), the 0x0-molybdenum(V) complexes (HBpzU3) MoO(X) (Y), (X, Y = C1-, NCS-, OR-, SR-, etc.)…”

Structure of hydridotris[3-(p-tolyl)pyrazolyl]boratothallium(I)

“…Recent work from these and other laboratories has demonstrated amply that the chemical and structural properties of poly(1-pyrazolyl)borato complexes are remarkably sensitive to changes in the nature of the substituent at the 3-position of the pyrazolyl groups (Desmond, Lalor, Ferguson, Ruhl & Parvez, 1983;Trofimenko, Calabrese, Domaille & Thompson, 1989;Trofimenko, Calabrese & Thompson, 1987). In connection with a study of Group VI transition metal complexes containing sterically crowded poly(1-pyrazolyl)borate ligands, we had occasion to prepare hydridotris [3-(p-tolyl)pyrazolyl]boratothallium(I), HB(p-MeC6Ha-C3H2N2)3T1 (1).…”

“…Complex (1) was prepared essentially as described by Trofimenko et al (1987) for the 3-phenyl analogue. * Colourless prisms of (1) were grown from dichloromethane/petrol by slow diffusion.…”

Chemistry of the p-block elements with anionic scorpionate ligands

“…It seems likely therefore that [Al(Tp * )Me2] is 5-coordinate. The difference in coordination numbers can be rationalised in terms of the cone angles, which for Tp 3-tBu is somewhat larger than Tp * [20].…”