With the most recent Open Babel version 2.4.1, xyz files containing heteroaromatics are not converted to mol files correctly in some cases. Taking triazine as an example, the following sequence of commands leads to different results in versions 2.3.2 and 2.4.1, respectively:
obabel -:"n1cncnc1" -O test.xyz --gen3d
obabel -ixyz test.xyz -omol
In version 2.3.2, the mol output is correct, whereas in version 2.4.1, a wrong radical structure is generated, ending in "M RAD 1 6 2
M END"