Modify real part and leaves imaginary part unchanged

-Conjugate[list]

(* {{0.282095 + 0.282095 I, 0.27254 + 0.291336 I, 
     0.262018 + 0.300835 I, 0.250437 + 0.310542 I}} *)

list /. Complex[x_, y_] :> Complex[-x, y]

{{0.282095 + 0.282095 I, 0.27254 + 0.291336 I, 0.262018 + 0.300835 I, 0.250437 + 0.310542 I, 2, 3 I}}

f[z_] = -Re[z] + I Im[z]
f[list]

(* {{0.282095 + 0.282095 I, 0.27254 + 0.291336 I, 0.262018 + 0.300835 I, 0.250437 + 0.310542 I}} *)