Complexes of Cobalt(II) Chloride with the Tripodal Trisphosphane triphos: Solution Dynamics, Spin-Crossover, Reactivity, and Redox Activity

Depending on the reaction conditions, different products are
obtained from the reaction of CoCl2 with
CH3C(CH2PPh2)3 (triphos), including the low-spin
complexes
[(triphos)Co(μ-Cl)2Co(triphos)]2+
(12+) and
[(triphos)CoCl2]
(3), their solid-state structures being determined by X-ray
methods. In solution, additionally, a four-coordinate
high-spin complex [(η2-triphos)CoCl2]
(2) is present, its concentration relative to that of
3 depending on the
solvent and the temperature. The reactivity of these species
toward Lewis acids is investigated leading to the
novel heterodinuclear complexes
[(triphos)Co(μ-Cl)2MCl2] (M =
Fe (5), Co (6)). Reactions with Lewis bases
L
yield complexes of the rare type
[(triphos)CoCl(L)]+ (L = CO
(7+), PMe3
(8+), NH3
(9+), CH3CN
(10+)). One-electron reduction of 3 leads to the previously prepared
pseudotetrahedral [(triphos)CoICl] complex
11, and one-electron oxidation to the novel trigonal-bipyramidal low-spin complex
[(triphos)CoIIICl2]+
(12+).