You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Biological activity of Pd(II) complexes with mono- and disubstituted pyridines-Experimental and theoretical studies. Due to the similarity between Pd and Pt, the complexes of palladium(II) can be considered as potential anticancer agents. Activity of six PdCl2(X2Py)2 complexes (Py=pyridine, and X=CH3 or Cl) was measured by MTT test using MCF7, CCRF-SB, PC3 and human B-lymphoblastoid cell lines. We found that the effect of PdCl2(XnPy)2 was cell-specific and time-dependent. Obtained results were discussed and compared with the activation parameters calculated for the hydrolysis of PdCl2(XnPy)2, indicating a correlation between viability of MCF7 and CCRF-SB cells and rates of hydrolysis of the Pd(II) complexes.
{"Chemical": ["Pd(II)", "pyridine", "PdCl2(XnPy)2", "mono- and disubstituted pyridines", "Pd", "palladium(II)", "Cl", "PdCl2(X2Py)2", "MTT", "CH3", "Pt", "Py"]}