Reduction of TiCl4 with 1 equiv of HSnBu(3) followed by addition of [PPh(4)]Cl and then PR(3) leads to two new dinuclear titanium(III) compounds, [PPh(4)] [Ti-2(mu-Cl)(3)Cl-4(PR(3))(2)] (R = Et and R(3) = Me(2)Ph), both of which contain an anion with the face-sharing bioctahedral type structure. Their crystal structures are reported. [PPh(4)][Ti-2(mu-Cl)(3)Cl-4(PEt(3))(2)]. 2CH(2)Cl(2) crystallized in the triclinic space group P (1) over bar. Cell dimensions : a = 12.461(1) Angstrom, b = 20.301(8) Angstrom, c = 11.507(5) Angstrom alpha = 91.44 degrees, beta = 113.27(1)degrees, gamma = 104.27(2)degrees, and Z = 2. The distance between titanium atoms is 3.03(2) Angstrom. [PPh(4)][Ti-2(mu-Cl)(3)Cl-4(PMe(2)Ph)(2)]. CH2Cl2 also crystallized in the triclinic space group P (1) over bar with cell dimensitions a = 11.635(4) Angstrom, b = 19.544(3) Angstrom, c = 11.480(3) Angstrom, alpha = 100.69(2)degrees, beta = 109.70(1)degrees, gamma = 95.08(2)degrees, and Z = 2. The distance between titanium atoms in this compound is 2.942(1) Angstrom. Variable temperature magnetic susceptibilities were measured for [PPh(4)][Ti-2(mu-Cl)(3)Cl-4(PEt(3))(2)]. Electronic structure calculations were carried out for a model ion, [Ti-2(mu-Cl)(3)Cl-4(PH3)(2)](-), and another well-known anion, [Ti-2(mu-Cl)(3)Cl-6](3-), by employing an nb initio configuration interaction method. The results of the calculations reveal that the metal-metal interaction in these Ti(III) face-sharing compounds can be best described by strong antiferromagnetic coulping that leads to a singlet ground state and a thermally accessible triplet first excited state. Accordingly the measured magnetic data were satisfactorily fitted to a spin-only formula.