NMR studies of ammoniated NaA"2C"6"0 superconductors

^1^3C-NMR studies of new class of C"6"0 superconductors, (NH"3)"xNaA"2C"6"0 with A=K or Rb, are reported. The results are compared with the other classes of A"3C"6"0 superconductors. In fee A"3C"6"0, an examination of the modified Korringa relation, T"1TK^2~@bS showed existence of weak but substantial antiferromagnetic spin fluctuation in A"3C"6"0; @b=0.40~0.58 with an error of +/-20 %. Stoner enhancement factor was also determined as 1~1.5. The temperature dependent T"1TK^2, which becomes significant at high temperature (>~100 K), is suggested to be explained by an enhancement effect related to short mean free path in the present materials. In (NH"3)"xNaA"2C"6"0, a gap-like behavior in temperature dependence of ^1^3C-spin lattice relaxation rate was observed. C"6"0 and NH"3 molecular dynamics are also discussed.