LOSS OF SEPARATION BTWN CLBING LJ25 AND A C210 AT FL180.

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ACFT #1; AN LJ25; DEPARTING NORFOLK CLBING TO 16000 FT. ACFT #2; A C210 AT FL180; TFC SBY TO CVI. TOOK A POINTOUT ON THE C210 FROM ORF TWR. LIMITED DATA BLOCK AT FL180. THE LEARJET DEPARTING ORF WAS CLBING TO 16000 FT; WHEN I INADVERTENTLY ISSUED CLB TO FL230. AT THE TIME I WAS WORKING THE ROCKY MOUNT SECTOR AND THE FRANKLIN SECTOR COMBINED AND WAS SATURATED WITH TFC IN BOTH SECTORS. ATTN WAS DIVERTED TO A VFR ACFT WHICH DEPARTED PGU LOOKING FOR AN IFR CLRNC. WAS UNABLE DUE TO TFC IN THE VICINITY OF THE REQUESTING ACFT. PLT OF VFR CALLED 3 ADDITIONAL TIMES FOR CLRNC WHICH WAS STILL ABLE TO MAINTAIN VFR; THEN LOOKED UP AT FKN VOR AND SAW THE LJ25 PASSING THROUGH 16400 FT FOR FL230. TRIED TO STOP THE LEAR AT 17000 FT BUT PLT SAID HE HAD JUST GONE THROUGH IT. THEN EXPEDITED THE DSCNT BACK DOWN TO 17000 FT. I FEEL THAT MY ATTN HAD BEEN DIVERTED BY TRYING TO EXPLAIN TO THE VFR WHY I WAS UNABLE TO GIVE AN IFR CLRNC WHEN I ISSUED THE CLB TO THE LEARJET. IN THE FUTURE I FEEL STARTING A TRACK ON THE LIMITED DATA BLOCK AT FL180; OR CALLING THE ACFT 'RADAR CONTACT;' INSTEAD OF APPROVING A POINTOUT WILL ALLEVIATE THIS PARTICULAR SIT.