REACTIONS OF TRANSITION-METAL CARBONYL DIANIONS WITH (ORGANO)GALLIUM CHLORIDES - ANIONIC GALLIUM COMPLEXES OF CHROMIUM, IRON, AND MANGANESE- STRUCTURE OF [PPN](2)([(CO)(4)FE-GA(CH3)-FE(CO)(4)])

Salt elimination reactions between the divalent transition carbonyl me talates [L(CO)(n)M](2-) (M = Cr, Mn, Fe; L = CO, NO; n = 3, 4) and the (organo)gallium halides ClaGaR3-a (R = CH3, CH2CH3; a = 1, 2, 3) as w ell as the intramolecularly donor stabilized species ClGa[(CH2)(3)NMe2 ](R) (R = Cl, Me, Bu-t) have been studied in some detail. Novel stable anionic (organo)gallium and chlorogallium metal complexes of the type s {[L(CO)(n)M]Ga[(CH2)(3)NMe2](R)}(-) (1-6), {[L(CO)(n)M]GaCl2}(-) (7, 8), {[L(CO)(n)M]Ga(Cl)(R)}(-) (9, 10), and {[L(Co)(n)M](2)Ga(CH3)}(2- ) (11-13) have been prepared in high yields and were fully characteriz ed by means of elemental analysis, infrared nu(CO) data, and NMR spect roscopy. The effect of substituents at the Ga center on the Lewis acid ity was studied by temperature-dependent NMR (inversion at the N atom of the alkylamine ligand) using the compounds 1-6. The compounds 7-10 are supposed to be dimeric. The dianionic complex [PPN](2){[(CO)(4)Fe- Ga(CH3)-Fe(CO)(4)]} (11a) was also characterized by single-crystal X-r ay diffraction: monoclinic, C2/c, a = 2699.1(3) pm, b = 1411.2(2) pm, c = 2392.8(3) pm, beta = 127.45(1)degrees, V = 7236 x 10(6) pm(3), Z = 4, and R = 0.038 (R-w = 0.097). The diminished Lewis acidity of the c ompounds 1-13 is explained by an electrostatic effect, which also stab ilizes low-coordinate Ga centers without steric shielding.