TRANSITION-METAL COORDINATED AL(X)L-2 AND GA(X)L-2 FRAGMENTS

Carbonylmetalate dianions react in thf with the group 13 chlorides XmE Cl3-m, (E = Al, Ga; X = Cl, Me, Et, Bu-i; m = 0, 1) to yield the monoa nionic species [(CO)(n)M-EXmCl2-m](-) (M = Fe, Cr, Mo, W; n = 4, 5) as the primary products which could be isolated as solvent free salts af ter exchange with a non coordinating cation. After addition of a chela ting Lewis base, e.g., tmeda, dme, and solvent exchange with dichlorom ethane the primary products undergo a second salt elimination reaction , yielding the neutral intermetallic systems (CO)(n)M-Ga[X(L)(2)] (M = Cr, Mo, W, Fe; n = 4, 5; X = Cl, Me, Et; L-2 = tmeda, dme, bipy, Bu-t -dab, thf(2)) (1-14) and (CO)(5)M-Al[X(L)(2)] (M = Cr, Mo, W; X = Cl, Et, Bu-i; L-2 = tmeda, tmpda) (15-20, 23, 24). The chloro derivatives can be converted to the corresponding hydride or tetrahydridoboranato species which is exemplarily shown by compounds 21 and 22. In the case of R2GaCl (R = Me, Et; 2 equiv) as starting compounds a ligand exchan ge reaction, generating GaR3, occurs, before the second salt eliminati on takes place. The new intermetallic systems were characterized by me ans of elemental analysis and IR, Raman, NMR, and mass spectroscopy. T he complexes (CO)(5)Cr-Ga[Cl(tmeda)] (2), (CO)(5)W-Al[Et(tmeda)] (20), and (CO)(5)W-Al[Cl(tmpda)] (23) are also characterized by single-crys tal X-ray diffraction. Compounds 2 and 20 crystallize in the monoclini c space group P2(1)/n, Z = 4. 2: a = 9.059(4) Angstrom, b = 16.084(7) Angstrom, c = 11.835(6) Angstrom, beta = 80.6(1)degrees, V = 1701(1) A ngstrom(3), and R = 0.037 (R-w = 0.118). 20: a = 8.606(2) Angstrom, b = 16.463(6) Angstrom, c = 12.469(4) Angstrom, beta = 93.88(2)degrees, V = 1762(6) Angstrom(3), and R = 0.027 (R-w = 0.065). Complex 23 cryst allizes in the orthorhombic space group Pccn, a = 23.990(6) Angstrom, b = 9.044(3) Angstrom, c = 15.871(4) Angstrom, V = 3445(1) Angstrom(3) , and R = 0.044 (R-w = 0.088). Ab initio quantum chemical calculations at the MP2 level of theory of the model complexes (CO)(5)W-E[Cl(NH3)( 2)] (E = B, Al, Ga, In, Tl), (CO)(5)W-Al[H(NH3)(2)], (CO)(5)W-AlH, and (CO)(5)W-AlCl are reported. The group-13 fragments E(R)L-2 behave as strong sigma-donors with significant acceptor capabilities. The W-E bo nds are strong semipolar covalent bends with large ionic contributions (D-e(calc) between 70 and 120 kcal/mol). Only the W-Tl bond is compar atively weak (D-e(calc) = 48 kcal/mol).