The synthesis of iron(II), cobalt(II) and nickel(II) complexes supported by chelating borate ligands containing one pyrazole and two thioethers, phenyl(pyrazolyl)bis((alkylthio)methyl)borates, [Ph(pz)Bt R ], is described. The six-coordinate complexes [Ph(pz)Bt] 2 M, M=Fe (1Fe), Co (1Co) and Ni (1Ni), form exclusively the cis isomers as confirmed by X-ray diffraction analyses. Whereas 1Co and 1Ni are high spin, 1Fe exhibits a room temperature magnetic moment, μ eff =4.1μ B , consistent with spin-crossover behavior. Quantitative analysis of the electronic spectrum of 2Ni leads to a value of D q =1086cm −1 , reflective of a ligand field strength somewhat weaker than those imposed by the related tridentate borate ligands Tp or PhTt. Replacement of the methylthioether substituent with the sterically more demanding tert-butylthioether leads to the isolation of [Ph(pz)Bt tBu ]MX, M=Co, X=Cl (2Co); M=Ni, X=Cl (2Ni) or acac (3). The solid state structures of 2Co and 2Ni are chloride-bridged dimers. Additional high-spin cobalt(II) complexes, accessible under distinct preparative conditions, [κ 2 -Ph(pzH)Bt tBu ] CoCl 2 ·THF (4) and [κ 2 -Ph(pz)Bt tBu ] 2 Co (5), have been fully characterized.