The significance of organometallic chemistry has constantly increased during the second half of this century. The Gmelin Institute recognizes this fact in publishing an entire series on organometallic compounds. This series has now started with the description of the organorhenium compounds. This volume is the second of a series of volumes dealing with organorhenium compounds. It continues the description of mononuclear organorhenium carbonyls with five and six CO groups, followed by the description of isonitrile compounds. Compounds containing CO groups and isonitrile ligands are covered in the section on isonitrile compounds. The volume continues with the description of mononuclear organorhenium compounds containing 2L, 3L, and 4L ligands (nL is an organic ligand bonded by n C atoms to rhenium). Compounds containing both a CO group or an isonitrile ligand and an nL ligand are described in the section concerning the nL ligand. The volume covers the literature completely up to the end of 1987. An empirical formula index and a ligand formula index provide ready access to the compounds covered.