... Addition- al hyperfine splitting occurs when a phenyl group is bonded to N-1 (but not N-4) in urazole radicals. ... 0022-326317811943-0808$01.00/0 1978 American Chemical Society Page 2. ... e: R = Ph, R' = Et f: R = Ph, R' = Me g: R = PhCMe,, R' = Et h: R = PhCMe,, R' = Me ...