Allan,
Your example points out why the Real Color Wheel can be of benefit to all of us. It is a wheel in which actual artists colors are noted. Thus we can instantly see if a tube color is fully saturated or grayed somewhat. It also helps us decide which tube colors we can us to help us create a true neutral or even a high quality black. In most cases we won't have a true complimentary tube color available to neutralize a color we have. The real color wheel can then help us choose some split complimetary tube colors to do the same job. Check out this interesting color wheel at:
http://realcolorwheel.com/colorwheel.htm.