A series of pyrazole-based potential ligands bearing thioether substituents in 3-and 5-positions of the heterocycle was synthesized [3,5- complex [ (lb)2Cu2](BF4)2 (4) was synthesized. According to an X-ray crystal structure analysis it consists of dinuclear molecules with two bridging pyrazolates, distorted square planar N2S2 coordination spheres for Cu" and an axially bridging tetrafluoroborate. Magnetic susceptibility data reveal an antiferromagnetic exchange ( J = -206 cm-l) that is among the highest found for doubly pyrazolate bridged dicopper(I1) complexes, which is rationalized on the basis of the rather symmetric dinuclear core of 4. The irreversibility of the electrochemical reduction and oxidation processes for the CuII and CuI compounds, respectively, is explained by the inability of the respective coordination framework to adapt to different geometric preferences.

Carbonylmetalate dianions react in thf with the group 13 chlorides X m ECl3 - m (E = Al, Ga; X = Cl, Me, Et, iBu; m = 0, 1) to yield the monoanionic species [(CO) n M−EX m Cl2 - m ]- (M = Fe, Cr, Mo, W; n = 4, 5) as the primary products which could be isolated as solvent free salts after exchange with a non coordinating cation. After addition of a chelating Lewis base, e.g., tmeda, dme, and solvent exchange with dichloromethane 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; L2 = tmeda, dme, bipy, tBu-dab, thf2) (1−14) and (CO)5M-Al[X(L)2] (M = Cr, Mo, W; X = Cl, Et, iBu; L2 = tmeda, tmpda) (15−20, 23, 24). The chloro derivatives can be converted to the corresponding hydrido 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 exchange reaction, generating GaR3, occurs, before the second salt elimination takes place. The new intermetallic systems were characterized by means of elemental analysis and IR, Raman, NMR, and mass spectroscopy. The complexes (CO)5Cr−Ga[Cl(tmeda)] (2), (CO)5W−Al[Et(tmeda)] (20), and (CO)5W−Al[Cl(tmpda)] (23) are also characterized by single-crystal X-ray diffraction. Compounds 2 and 20 crystallize in the monoclinic space group P21/n, Z = 4. 2:  a = 9.059(4) Å, b = 16.084(7) Å, c = 11.835(6) Å, β = 80.6(1)°, V = 1701(1) Å3, and R = 0.037 (R w = 0.118). 20:  a = 8.606(2) Å, b = 16.463(6) Å, c = 12.469(4) Å, β = 93.88(2)°, V = 1762(6) Å3, and R = 0.027 (R w = 0.065). Complex 23 crystallizes in the orthorhombic space group Pccn, a = 23.990(6) Å, b = 9.044(3) Å, c = 15.871(4) Å, V = 3445(1) Å3, and R = 0.044 (R w = 0.088). Ab initio quantum chemical calculations at the MP2 level of theory of the model complexes (CO)5W−E[Cl(NH3)2] (E = B, Al, Ga, In, Tl), (CO)5W−Al[H(NH3)2], (CO)5W−AlH, and (CO)5W−AlCl are reported. The group-13 fragments E(R)L2 behave as strong σ-donors with significant acceptor capabilities. The W−E bonds are strong semipolar covalent bonds with large ionic contributions (D e(calc) between 70 and 120 kcal/mol). Only the W−Tl bond is comparatively weak (D e(calc) = 48 kcal/mol).

Reaction of tripod cobalt(r1) templates [{CH,C(CH,PAr,),}Co"] with potentially bridging ligands L generates the dinuclear compounds (1) is formed. while with L = C,H,O:-, the dianion derived from 2,5-dihydroxy-I ,4-benzoquinone (anilic acid), two-electron transfer within the dimetallic unit occurs and a biscobalt(i1i) charge distribution results (2a), as shown by X-ray structural analyses of 1 and 2 a, N M R spectroscopy, and theoretical investigations by the INDO method. Complex 2 a exhibits an

Mesitylcopper reacts with flavonol (flaH) in the presence of 1,3-bis(2-pyridylimino)isoindoline (indH) to yield the diamagnetic complex CuI(fla)(indH), which on reaction with molecular oxygen undergoes oxidative splitting of the C2-C3 bond of the pyranone ring of the flavonolate ligand to give CuI(indH)(O-bs) (O-bs = O-benzoylsalicylate) (orthorhombic, P1, a = 8.048(7) A, b = 8.969(9) A, c = 19.240(2) A, alpha = 85.69 degrees, beta = 80.24(7) degrees, gamma = 77.87(7) degrees, V = 1337(2) A3, Z = 2) and carbon monoxide. The reaction of [CuI(CH3CN)4]ClO4, flaH, and indH with dioxygen at room temperature affords the paramagnetic complex [CuII(fla)(indH)]ClO4 (mu = 2.10 mu B), and after elimination of HClO4, CuII(fla)(ind) (orthorhombic, Pbca, a = 8.888(2) A, b = 19.169(7) A, c = 33.614(10) A, alpha = beta = gamma = 90 degrees, V = 5727(3) A3, Z = 8) with mu = 1.86 mu B is formed. The latter undergoes cleavage of the pyranone ring on oxygenation at 80 degrees C to give CuII(ind)(O-bs) (mu = 1.87 mu B, nu(CO) = 1742 cm-1, and nu(CO2) = 1581, 1387 cm-1) and carbon monoxide. CuII(fla)(ind) and [CuII(fla)(indH)]ClO4 serve as good catalysts for the oxygenation of flavonol to O-benzoylsalicyclic acid.