Copper(II) Complexes with 4-Amino-N-[4,6-dimethyl-2-pyrimidinyl]benzenesulfonamide. Synthesis, Crystal Structure, Magnetic Properties, EPR, and Theoretical Studies of a Novel Mixed μ-Carboxylato, NCN-Bridged Dinuclear Copper Compound

Abstract

New Cu(II) complexes of sulfamethazine (4-amino-N-[4,6-dimethyl-2-pyrimidinyl]benzenesulfonamide, HL) [Cu(2)(CH(3)COO)(2)(L)(2)].2dmf (1) and ([Cu(L)(2)].2H(2)O)(infinity) (2) were prepared and structurally characterized. Compound 1 crystallizes in the monoclinic system, space group P2(1)/n, with a = 8.9486(9) A, b = 15.0956(12) A, c = 16.542(3) A, beta = 105.584(15) degrees, and Z = 2. Compound 2 crystallizes in the monoclinic system, space group P2(1)/c, with a = 13.8097(8) A, b = 14.5765(4) A, c = 13.7853(15) A, beta = 96.033(9) degrees, and Z = 1. In compound 1 two copper ions are linked by two syn-syn acetates and two nonlinear NCN bridging groups pertaining to the deprotonated sulfamethazine ligands. Each copper center presents a nearly square planar geometry. Magnetic susceptibility data for 1 show a strong antiferromagnetic coupling with 2J = -216.7 cm(-)(1). The EPR spectra at the X- and Q-band frequencies present the signals corresponding to the dinuclear entity, being the zero-field splitting parameter, D = 0.265 cm(-)(1). The antiferromagnetic exchange coupling is discussed using DFT calculations on some model compounds with NCN bridging ligands and also on model structures with mixed mu-acetato and NCN bridges. The copper in the polymeric compound 2 is five coordinate. The CuN(5) chromophore has a highly distorted square pyramidal geometry with small axial N-Cu-N angles of 65.53(14) and 59.90(13) degrees. In the structure a sulfamethazinate anion binds to one copper through the sulfonamido and pyrimidine N atoms and to an adjacent copper via the amino N atom.

Paramagnetic Properties of the Halide‐Bound Derivatives of Oxidised Tyrosinase Investigated by 1H NMR Spectroscopy

“…[16] The dipolar interaction in a Cu 2 pair with the coppers 2.5 apart contributes 0.1 cm À1 to the zero-field splitting parameter D in Cu 2 model compounds. [44] The spin-orbit coupling is not expected to contribute appreciably either. In agreement with this, common values for D are in the range of 0.2-2 cm À1 (e.g.…”

“…refs. [44]- [48]), which is small relative to the Zeeman energy in a 14 T field and small relative to k B T. Thus, the contribution to d pc is predicted to be negligible. [16] [28] From NMR and kinetic experiments on halide binding to Ty met , it has been found that halide-free Ty met and halide-bound Ty met are in slow exchange on the NMR time scale (the measured k off of the Cu 2 bridging F À amounts to 14 s À1 at pH 6.8 [19] ).…”

Development of novel copper(II) complexes of benzothiazole-N-sulfonamides as protective agents against superoxide anion. Crystal structures of [Cu(N–2-(4-methylbenzothiazole)benzenesulfonamidate)2(py)2] and [Cu(N–2-(6-nitrobenzothiazole)naphthalenesulfonamidate)2(py)2]

“…To this end, we have synthesized a variety of mono-and dinuclear compounds and studied them extensively [24,25,26,27,28,29,30,31,32,33]. Recently we have also become interested in ternary sulfonamide complexes with SODlike activity.…”

Spectroscopic, magnetic, and electrochemical studies of a dimeric N-substituted-sulfanilamide copper(II) complex. X-ray and molecular structure of the Cu2(N-(pyridin-2-yl)biphenyl-4-sulfonamidate)4 complex

“…The fitting result for the complex was R = 1.7 Â 10 À3 . In previous papers [21,22,34] we have reported the J values of different copper dimer complexes with NCN bridges. We have shown that in spite the fact that the CuÁÁÁCu distance in the copper sulfathiazolato is lower than in other copper dimers with NCN bridges such as adenine copper complexes [5,11,12], the value of J is significantly lower than the value observed for these adenine complexes.…”

“…It shows an interesting magnetic and EPR behavior characteristic of an antiferromagnetic compound, but its antiferromagnetism is lower than that of the copper(II) adenine complexes. Recently, we have reported the crystal structure and properties of a copper(II) dimer with the metallic centers bridged by a NCN group and by a carboxylato anion [22]. Latest, we have described a copper(II) complex with the two adeninate anions that behave as NCN type bridging ligands between two copper(II) ions [23].…”