Enroute Controller described a loss of separation event; listing coordination distractions as a causal factor.

Narrative

A C680 was in level flight direct to the VOR level at 21;000 FT. I recognized the possible traffic situation and left an Air Carrier level at 22;000 FT for the C680. A Military aircraft was exiting a Restricted Area requesting an IFR [clearance]. I was taking that coordination from the D-Side around the time the A300 checked in. I descended the A300 to 20;000 FT. I knew that I needed to sequence the Air Carrier and the A300 and an overtake situation was underway. The Military checked in requesting an IFR and asking me to deactivate the Restricted Airspace. I took coordination from the D-Side about the Restricted Area. The military aircraft explained he wanted to go VFR; and then became unsure. He then asked if he could go VFR. His confusion took a lot of my attention. Once I sorted out the Military flight I recognized the situation with the A300 and the C680. I turned the A300 20 left and the C680 20 left and called traffic for both. D-Side training was underway at my sector. I was taking a lot of irrelevant coordination at times when I needed to be handling other situations. I allowed myself to focus on the aircraft that was requesting all of the attention. As controllers we know how to continually scan and not let a pilot keep your attention. In the future I need to continue to move through the sector and not let a D-Side or a confused pilot try and demand all of my attention when they don't need it.