The versatility of the dihydrogenobis(1-pyrazolyl)borate ligand, H2B(pz)2–: novel anionic complexes with chromium(II), chromium(III), and manganese(II). X-Ray structure of [AsPh4][MnCl{H2B(pz)2}2]
Abstract
New five-co-ordinate chromium(II) and manganese(II) complexes with the ligand dihydrogenobis(1-pyrazolyl)borate, H2B(pz)2, have been prepared and characterized. The complexes have the general formula A[MX{H2B(pz)2}2](M = CrII or MnII; A = NEt4, PPh4, or AsPh4; X = halides or pseudohalides). All of the complexes are high spin. The structure of [AsPh4][MnCl-{H2B(pz)2}2] has been determined by single-crystal X-ray diffraction methods. The compound crystallizes in the space group P21/n with a= 16.952(4), b= 13.039(3), c= 17.331(4)Å, β= 105.53(2)°, and Z= 4. The structure was solved by heavy-atom methods and refined to R= 0.058. The co-ordination geometry about manganese(II) is square pyramidal with the four donor N atoms of the two H2B(pz)2 ligands forming the basal plane and the Cl atom occupying the apical position. The Mn atom is displaced by 0.52 Å from the base of the pyramid toward the Cl atom. Slow oxidation of [NEt4][Cr{H2B(pz)2}2(NCS)] in solution yields the chromium(III) complex [NEt4][Cr2(EtO)3{H2B(pz)2}2(NCS)2] with co-ordinated ethoxo groups.