Another Surprise from Pyrazolate Ligands

Abstract

The unexpected versatility of pyrazolate ligands R2pz is demonstrated by the synthesis of the homoleptic titanium complexes of the type [Ti(η2‐R2pz)4] (1, R = Me, Ph) by Winter et al. Hitherto, pyrazolate ions were commonly bridging (µ2) or more rarely unidentate ligands for d‐block transition metals.

Structural, spectroscopic and computational studies of the HgL2Cl2 complex (L = 3,5-dimethyl-1-thiocarboxamide pyrazole) and the crystal structure of L

“…5 In recent years, metal complexes with pyrazole type ligands have been introduced as precursors in metal organic vapour deposition (MOCVD) processes. [6][7][8] The chemistry and the reactions of pyrazole type complexes have been described in detail in several review articles. [9][10][11][12] Our systematic studies of transition metal complexes with pyrazole derivatives [13][14][15][16] have the aim to synthesise new compounds with structural properties that fulfil the specific stereochemical requirements of a particular metal-binding site and to determine the conditions of complex formation in order to understand the factors governing reaction pathways.…”

Transition metal complexes with pyrazole-derived ligands. X. [Zn(CH3COO)2L2].2MeOH (L= 3-amino-5-phenylpyrazole)

“…Pyrazole derivatives and their metal complexes have recently attracted the attention of numerous researchers, which is evident from the publication of a large number of research papers and several reviews (Trofimenko, 1972(Trofimenko, , 1986(Trofimenko, , 1993Cosgriff & Deacon, 1998). This class of ligand is characterized by a diversity of coordination The zinc ion is coordinated with two O atoms from the carboxylate groups and two pyridine-N atoms from 3-amino-5-phenylpyrazole ligands in a distorted tetrahedral arrangement.…”

Divalent metal complexes (Ca, Sr, Ba, Yb) of the unsymmetrical 3-(2′-thienyl)-5-(trifluoromethyl)pyrazolate ligand

“…1, 29 Outcomes, in particular for 3,5-disubstituted pyrazolates, include mono-, 7,8,17,23 di-9,11-16,20-22 and oligonuclear 15,20 as well as polymeric 5,9,10 and cluster-like structures 2,3,18, 19 with the pyrazolate ligand exhibiting many coordination modes. h 2 -Bonding was for many years the sole domain of f-elements, 30 but now has become widespread. 1 Some examples of exclusively h 2 -bound pyrazolate species of trivalent metals include [Ln(Ph 2 pz) 3 (dme) 2 ](dme) (Ln = Nd, Eu; Ph 2 pz = 3,5-diphenylpyrazolate), 4 [Ln(tBu 2 pz) 3 (thf) 2 ] (Ln = Nd, 7 Er; 8 tBu 2 pz = 3,5-di-tert-butylpyrazolate) and complexes with various transition [31][32][33][34][35] and main group metals.…”