The solid-state reactions occurring during the moderation of recoiling Cl-38, produced by the Cl-37(n,gamma)Cl-38 nuclear reaction, were studied in mixed potassium hexa(chloro/fluoro)osmates(IV), K2OsClnF6-n (n = 1-5) with special attention to the cis/trans (n=2,4) and fac/mer (n=3) isomers. The results were discussed within the scope of the "Impact-Induced Multiple Ligand Abstraction" (IMULA) model, the central point of which is the production of transient ligand vacancy complex anions MCl-38(X,Y)n(square)5-n2- (X,Y = Cl, F; square = ligand vacancy) and which concerns the reactions of halide recoil atoms at the end of their trajectories. Contrary to the predictions of the model that no fac-(OsClCl2F32-)-Cl-38 should be produced from trans-K2OsCl2F4 and no trans-(OsClCl3F22-)-Cl-38 from fac-K2OSCl3F3, these species were found (7% and 4%, respectively). The unexpected result can be accounted for if it is postulated that the configurations of the ligand vacancy complex anions are labile and can turn into other ones before reacting with adjacent halide ions to complete (OsClX52-)-Cl-38 complex anions.