Synthesis and structural characterization of tris(2-mercapto-1-methylbenzimidazolyl)hydroborato cadmium halide complexes, {[Tm^MeBenz]Cd(μ-Cl)}₂and [Tm^MeBenz]CdI: a rare example of cadmium in a trigonal bipyramidal sulfur-rich coordination environment

Abstract

The tris(2-mercapto-1-methylbenzimidazolyl)hydroborato cadmium complexes, {[TmMeBenz]Cd(µ–Cl)}2 and [TmMeBenz]CdI, have been synthesized via the reactions of [TmMeBenz]K with CdCl2 and CdI2, respectively. While X-ray diffraction studies demonstrate that the iodide derivative, [TmMeBenz]CdI, is a monomer, the chloride derivative, {[TmMeBenz]Cd(µ–Cl)}2, exists as a dimer, which is unprecedented for Group 12 [TmR]MX (X = Cl, Br, I) compounds. Furthermore, the cadmium centers of {[TmMeBenz]Cd(µ–Cl)}2 are trigonal bipyramidal, which is an uncommon motif for cadmium complexes with a [S3Cl2] coordination sphere.

Influence of benzannulation on metal coordination geometries: Synthesis and structural characterization of tris(2-mercapto-1-methylbenzimidazolyl)hydroborato cadmium bromide, {[TmMeBenz]Cd(μ-Br)}2

“…Furthermore, the tendency to form the dimeric structure increases in the sequence I < Br < Cl. The latter trend is in accord with the experimental observation that {[Tm MeBenz ]Cd(μ–Br)} 2 and {[Tm MeBenz ]Cd(μ–Cl)} 2 12 exist as dimers in the solid state, but [Tm MeBenz ]CdI 12 is a monomer.…”

“…4,5,6 For example, we have used [Tm R ] ligands both to ( i ) model aspects of metalloenzymes that feature sulfur-rich active sites and ( ii ) mimic the interactions of toxic metals such as mercury, cadmium and lead with cysteine thiolate groups. 7–12 One reason for the widespread use of [Tm R ] ligands is the fact that the properties of the ligand can be readily tailored by variation of the R substituents, in a manner akin to that of the tris (pyrazolyl)hydroborato [ N 3 ] donor ligand system. 4,5 In this regard, while the most common variation pertains to the nature of the 1-R substituent, 13 we recently introduced tris (mercaptoimidazolyl)hydroborato ligands, namely [Tm MeBenz ] and [Tm Bu t Benz ], in which the imidazolyl groups are benzannulated.…”

Synthesis and Structures of Cadmium Carboxylate and Thiocarboxylate Compounds with a Sulfur-Rich Coordination Environment: Carboxylate Exchange Kinetics Involving Tris(2-mercapto-1-t-butylimidazolyl)hydroborato Cadmium Complexes, [TmBut]Cd(O2CR)

“…Although a variety of [Tm Bu t ]­CdX complexes are known, ,, there are no reports of structurally characterized carboxylate derivatives . A series of such compounds, namely, [Tm Bu t ]­Cd­(O 2 CR) [R = C 6 H 4 -4-Me, C 6 H 4 -4-F, C 6 H 3 -3,5-F 2 , C 6 H 3 -2,6-F 2 , 9-anthryl (9-An), n -C 13 H 37 , and C 3 H 6 Ph], may, nevertheless, be synthesized via the reactions of [Tm Bu t ]­CdMe with RCO 2 H (Scheme ).…”

Crystal structure of hexa-μ-chlorido-μ4-oxido-tetrakis{[1-(2-hydroxyethyl)-2-methyl-5-nitro-1H-imidazole-κN 3]copper(II)} containing short NO2...NO2 contacts

“…The 5 geometry index is a general descriptor of five-coordinate molecules and provides a way to determine the extent of distortion of a molecule from trigonal bipyramidal to square pyramidal (Addison et al, 1984). The 5 geometry index is calculated by using the equation: 5 = ( À )/60, where À is the difference between the two largest angles (Addison et al, 1984;Palmer & Parkin, 2014). The values for 5 are calculated to be 0.65 (Cu1), 0.74 (Cu2), 0.84 (Cu3) and 0.73 (Cu4) for the five-coordinate copper centers, giving an average 5 value of 0.74.…”