The title compound, [Co(C(27)H(25)O(2)P(2))I(C(3)H(9)P)], was synthesized by the addition of 1-iodo-butane to a solution of the parent cobalt complex {1,3-bis-[(diphenyl-phosphan-yl)-oxy]prop-2-yl}bis-(trimethyl-phosphane)cobalt(II). Two five-membered cobaltocycles with considerable ring bending (sum of inter-nal angles = 516.4 and 517.7°) are formed through two P atoms of the PPh(2) groups and a metallated Csp(3) atom. The Co(II) atom is centered in a trigonal-bipyramidal configuration.