3 CLASSES OF 7-COORDINATE TUNGSTEN(II) CHELATES WITH BOTH HARD AND SOFT DONORS

Three types of mixed-ligand tungsten(II) chelates have been isolated with simultaneous coordination of hard phenolato oxygen, borderline heterocyclic nitrogen, and soft carbonyl and phosphine donors. The complexes are W(CO)2(PPh3)(dcq)2, W(CO)3(PPh3)(dcq)Cl, and W(CO)2(PPh3)2(dcq)Cl, where Ph=C6H5 and dcq-=5,7-dichloro-8-quinolinolato. A strong base (e.g., proton sponge) is necessary to prepare the bis-dcq- chelate from W(CO)3(PPh3)2Cl2 and Hdcq. The physical and chemical properties of the diamagnetic chelates are consistent with seven-coordinate geometries. © 1979, American Chemical Society. All rights reserved.