The intermolecular interaction between NH3 and F-2 was investigated systematically with the aid of several electron correlation methods ranging from MP2 to the CCSD(T) level applying extended basis sets. Despite the weak charge transfer character of the NH3-F-2 complex, electron correlation contributions beyond MP2 do have a significant influence on the properties of the complex. Moreover, structure optimization with explicit inclusion of the counterpoise correction leads to a substantial lengthening of the computed intermolecular distance. Convergence with respect to basis set extension is considerably slower and sensitivity to the correlation method applied is much greater than in related hydrogen-bonded complexes.