Novel stable and volatile organoindium transition metal complexes of the type [L(CO)(n)M]a[InR3-a(D)] (1-12 : M = Mo, W, Mn, Re, Fe, Co, Ni; L = eta5-C5H5, CO; R = CH2SiMe3, (CH2)3NMe2; D = O-, N-donor; n = 1-4; a = 1, 2) have been prepared in high yields by the reaction of the alkali metalates [L(CO)(n)M](Na/K) with organoindium halides InR2X (X=Cl, Br), and have been fully characterized by elemental analysis, IR, NMR, and mass spectrometry. The (3-dimethylamino) propyl-substituted alkylindium transition metal complexes are unusually stable toward ligand redistribution equilibria. Depending on the nature of the transition metal fragment, e.g. steric bulk and radical stability, compounds with transition metal to indium ratios of 1:1 and 2:1 are thermodynamically preferred. The transition metal indium bonds in these compounds were shown to be easily cleaved by electrophilic and nucleophilic attack, oxidation and photolysis. Single-crystal data are as follows. [(CO)4Co]2In[CH2Si(CH3)3](C4H8O), 1 : triclinic, P1BAR with a = 932.1(2) pm, b = 1054.2(2) pm, c = 1257.7(3) pm, alpha = 80.19(2)-degrees, beta = 80.55(2)-degrees, gamma = 85.05(2)-degrees, V = 1199 X 10(6) pm3, Z = 2, and R = 0.039 (R(w) = 0.025). [(eta5-C5H5)(CO)n]M-In[(CH2)3N(CH3)2]2 (4, M = Fe, n = 2; 5, Ni; n = 1) : 4, monoclinic, P2(1)/c, with a = 1329.1(3) pm, b = 978.4(2) pm, c = 1524.8(3) pm, beta = 95.53(1)-degrees, V = 1974 X 10(6) pM3, Z = 4, and R = 0.032 (R(w) = 0.039); 5a (T = -80-degrees-C), monoclinic, P2(1)/n with a = 967.4(5) pm, b = 1507.0(2) pm, c = 1332.0(5) pm, beta = 103.69(2)-degrees, V = 1887 X 10(6), pm3 Z = 4, and R = 0.048 (R(w) = 0.030). (mu-CO){mu-In[(CH2)3N(CH3)2]}[(eta5-C5H5)(CO)Fe]2, 12 : orthorhombic, Pnma with a = 1533.0(2) pm, b = 1253.7(1) pm, c = 1007.2(1) pm, V = 1936 X 10(6) pM3, Z = 4, and R = 0.041 (R(w) = 0.025).