Inorganic Chemistry, Vol.37, No.7, 1473-1482, 1998
Homo- and heterometallic mono-, di-, and trinuclear Co2+, Ni2+, Cu2+, and Zn2+ complexes of the "heteroscorpionate" ligand (2-hydroxyphenyl)bis(pyrazolyl)methane and its derivatives
H-1 NMR spectra on the paramagnetic Co-II and Ni-II, ML2 "sandwich" complexes of the "heteroscorpionate" ligands (2-hydroxyphenyl)bis (pyrazolyl)methane and its derivatives revealed the presence of isomeric, cis <----> trans equilibria of these complexes in solution. The presence of some of the cis isomer in solution at equilibrium has been exploited to synthesize new heterometallic trinuclear species of the type [M1(L1O)(2)M2(L1O)(2)M][BF4], where M1 (octahedral) and M2 (tetrahedral) are Zn2+, Cu2+, Ni2+, and Co2+. Rearrangements during the synthesis of some of these heterometallic species provided an interesting experimental confirmation of the site preferences (octahedral vs tetrahedral) for the first-row transition metals as predicted on the basis of crystal field stabilization energies. X-ray crystallographic characterization of many of the complexes reported in this study gives the following structural parameters : [Co-2(L2O)(2)Cl-2]. MeCN, C36H41N9Cl2Co2O2, monoclinic, a=10.742(1) Angstrom, b=21.387(2) Angstrom, c=16.890(2) Angstrom, beta = 95.506(8)degrees, space group P2(1)/c, Z = 4; [Co-3(L2O)(4)]Cl-2 . 5.2H(2)O, C68H76N16Cl2Co3O9.2, tetragonal, a=17.998(1) Angstrom, c=28.804(3) Angstrom, space group I4(1)/a, Z=4; [Co(C1O)(2)Na(L1O)(2)Co][BF4]. 0.5H(2)O . 0.5(1)Pr(2)O . 2MeCN, C59H44N18BCo2F4NaO5, monoclinic, a = 14.377(3) Angstrom, b = 18.712(2) Angstrom, c = 26.732(2) Angstrom, beta = 103.30(1)degrees, space group P2(1)/c, Z = 4; [Co-3(L2O)(4)][BF4](2) . 2H(2)O . 0.5(1)Pr(2)O, C35.5H41.5N8BCo1.5F4O3.25, orthorhombic, a = 19.076(2) Angstrom, b = 13.872(1) Angstrom, c=16.363(2) Angstrom, space group P2(1)2(1)2(1), Z = 4; [Co-3(L2O)(4)]- [BF4](2) . MeCN, C70H79N17B2CO3F8O4, monoclinic, a = 22.047(4) Angstrom, b = 16.155(2) Angstrom, c = 21.343(3) Angstrom, beta = 92.86(1)degrees, space group : C2/c, Z = 4; [Ni(L1O)(2)Co(L1O)(2)Ni][BF4](2) . 2MeCN, C56H50N18B2CoF8Ni2O4, monoclinic, a = 40.782(3) Angstrom, b = 16.511(2) Angstrom, c = 19.891(1) Angstrom, beta = 111.508(6)degrees, space group C2/c, Z = 8; [Ni(L1O)(2)Zn(L1O)(2)Ni][BF4](2) . MeCN, C54H44N8B2F8Ni2O4Zn, monoclinic, a=12.374(1) Angstrom, b = 26.481(4) Angstrom, c=18.651(4) Angstrom, beta = 103.69(1)degrees, space group C2/c, Z = 4; [Co(L1O)(2)Zn(L1O)(2)Co][BF4](2), C60H61N17B2Co2F8O5Zn, triclinic, a = 15.071(2) Angstrom, b = 15.331(2) Angstrom, c = 17.148(2) Angstrom, alpha = 65.120(7)degrees, beta = 68.905(8)degrees, gamma = 71.678(8)degrees, space group P (1) over bar, Z = 2.