The salt elimination reactions of [NEt4][Mo(CSe)(CO)2(Tp*)] ([NEt4][2], Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate) with a range of metal halide complexes (ClMLn) have been investigated as a possible route to isoselenocarbonyl complexes [Mo(CSeMLn)(CO)2(Tp*)]. Thus the reactions of [NEt4][2] with [RuCl(L)2(η-C5R5)] provide molybdenum-ruthenium derivatives [Mo{CSeRu(L)2(η-C5R5)}(CO)2(Tp*)] (L = PPh3, R = H 4, L = CO, R = Me 5), both of which were structurally characterised. The molybdenum-iron derivative [Mo{CSeFe(CO)2(η-C5H5)}(CO)2(Tp*)] (6) was obtained from [NEt4][2] and [FeCl(CO)2(η-C5H5)] however its formulation currently rests on spectroscopic and microanalytical data. The reaction of [NEt4][2] with [RuH(NCMe)(CO)2(PPh3)2]PF6 affords the structurally characterised hydrido-isoselenocarbonyl complex [Mo{CSeRuH(CO)2(PPh3)2}(CO)2(Tp*)] (7) with no indication of coupling of the hydride and selenocarbonyl ligand.