x(1) refers to only the first element in some variable x, and similarly, x(2) refers to only the second element. So you can't assign two values to x(1) as you've tried to do with
x(1) = (-5.3185, -2.302585);
One way to do it is to assign x and y values separately:
x = [-5.3185 -10.0332 -14.6496 -19.2959];
y = [-2.302585 -4.6052 -6.9078 -9.2103];
plot(x,y, '*-')
