Two approaches towards the synthesis of phosphine ligated half-sandwich complexes [(η x -C x H x )M(PR 3) 2GaI 2] n containing diiodogallyl ligands have been investigated. Insertion of ‘GaI’ into the Mo–I bond of (η 7-C 7H 7)Mo(CO) 2I has been shown to yield the crystallographically characterized dimeric complex [(η 7-C 7H 7)Mo(CO) 2GaI 2] 2 ( 2). Attempts to substitute the carbonyl ligands by the phosphine ligand dppe [dppe = bis(diphenylphosphino)ethane] have been shown instead to yield the sparingly soluble complex [(η 7-C 7H 7)Mo(CO) 2GaI 2] 2(μ-dppe) ( 3) in which the phosphine bridges two [(η 7-C 7H 7)Mo(CO) 2GaI 2] units via a pair of P → Ga donor/acceptor bonds. By contrast, attempts to insert ‘GaI’ directly into the metal-halogen bond of phosphine ligated complexes such as (η 5-C 5H 5)Ru(PPh 3) 2Cl or (η 5-C 5H 5)Ru(dppe)Cl have been shown to result in the formation of the tetraiodogallate species(η 5-C 5H 5)Ru(PPh 3) 2(μ-I)GaI 3 ( 5) and [(η 5-C 5H 5)Ru(dppe)] +[GaI 4] − ( 7).