Copper(I) complexes of the tridentate thioether ligands [PhB(CH(2)SCH(3))(3)] (abbreviated PhTt), [PhB(CH(2)SPh)(3)] (PhTt(Ph)), [PhB(CH(2)S(t)()Bu)(3)] (PhTt(t)()(Bu)), and [PhB(CH(2)S(p)()Tol)(3)] (PhTt(p)()(Tol)) and bidentate thioether ligands [Ph(2)B(CH(2)SCH(3))(2)] (Ph(2)Bt), [Et(2)B(CH(2)SCH(3))(2)] (Et(2)Bt), and [Ph(2)B(CH(2)SPh)(2)] (Ph(2)Bt(Ph)) have been prepared and characterized. The solution and solid state structures are highly sensitive to the identity of the borato ligand employed. Ligands possessing the smaller (methylthio)methyl donors, [PhTt] and [Ph(2)Bt], yielded tetrameric species, [(PhTt)Cu](4) and [(Ph(2)Bt)Cu](4), containing both terminal and bridging thioether ligation. The ligands containing the larger (arylthio)methyl groups, [PhTt(Ph)] and [PhTt(p)()(Tol)], form monomeric [PhTt(Ar)]Cu(NCCH(3)) in solution and one-dimensional extended structures in the solid state. Each complex type reacted cleanly with acetonitrile, pyridine, or triphenylphosphine generating the corresponding four-coordinate monomer, of which [PhTt(Ph)]Cu(PPh(3)), [PhTt(p)()(Tol)]Cu(PPh(3)), and [Et(2)Bt]Cu(PPh(3))(2) have been structurally characterized.

The synthesis and characterization of a series of [RTt]2M (RTt- = tetrakis((methylthio)methyl)borate; M = Fe, Co, Ni) complexes are reported. Isostructural derivatives of the newly synthesized phenyltris((methylthio)methyl)borate (PhTt-) also have been prepared and characterized. In each case, the ligand provides tridentate, face-capping coordination to the divalent metal ion. The Fe(II) complexes exhibit spin-crossover behavior both in solution and in the solid state. For [PhTt]2Fe, the temperature dependence of μeff has been mapped between 5 K (1.3 μB) and 400 K (3.2 μB). The low-spin Co(II) derivatives exhibit characteristic axial EPR spectra; for [PhTt]2Co, g ⊥ = 2.185, g ∥ = 2.035, A ⊥ = 55 G, and A ∥ = 42 G. Using O h Fe(II) and Co(II) derivatives as benchmarks, the ligand field strength imparted by these anions is significant and falls just below that of the neutral macrocycle 1,4,7-trithiacyclononane (ttcn). All complexes have been characterized by X-ray diffraction. X-ray data:  [PhTt]2Fe·0.6Et2O, monoclinic space group C2/c, with a = 22.293(4) Å, b = 12.842(8) Å, c = 15.326(2) Å, β = 130.28(6)°, V = 3347.4(5) Å3, and Z = 4; [RTt]2Co, triclinic space group P1̄, with a = 8.396(6) Å, b = 8.850(2) Å, c = 9.124(4) Å, α = 107.43(2)°, β = 92.20(4)°, γ = 94.50(4)°, V = 643.0(3) Å3, and Z = 1; [PhTt]2Co, monoclinic space group P21/c, with a = 8.821(1) Å, b = 14.127(8) Å, c = 12.055(3) Å, β = 103.93(2)°, V = 1458.0(5) Å3, and Z = 2; [RTt]2Ni, triclinic space group P1̄, with a = 8.607(3) Å, b = 8.876(3) Å, c = 9.173(3) Å, α = 107.44(2)°, β = 92.92(2)°, γ = 93.38(2)°, V = 665.70(3) Å3, and Z = 1; [PhTt]2Ni:  triclinic space group P1̄, with a = 8.627(7) Å, b = 8.862(4) Å, c = 10.559(6) Å, α = 75.08(4)°, β = 76.64(5)°, γ = 72.71(5)°, V = 734.3(8) Å3, and Z = 1.

A homoleptic copper(1) tetramer, [Cu(PhTt)14 1, is synthesized using phenyltris[(methylthio)methyl)]borate, PhTt-; X-ray analysis shows the four copper ions are nearly coplanar and each resides in an approximately tetrahedral environment; although 1 is stable towards 0 2 , H 2 0 and CO, it reacts with PPh3, pyridine, or [NEt4]SPh to yield the corresponding monomer, [Cu(PhTt)L] (L = PPh3 2, py 3, [NEt4]SPh 4).

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