A functionalized R,ω-bis(phosphite-donor) ligand containing two amido groups, 8, has been prepared from tartaric acid. An in situ formed rhodium(I) metallacrown ether complex of 8 has been compared to an in situ formed rhodium(I) complex of (R,R)-Chiraphite for the hydroformylation of styrene. Both Rh(I) complexes are active catalysts, but the complex of (R,R)-Chiraphite exhibits a higher regioselectivity than does the metallacrown ether catalyst (iso/n of 10.1 versus 3.9) as expected. The additions of alkali metal salts to the hydroformylation reactions cause increases in the regioselectivities (approximately 2-fold for both LiBPh 4 • 3dme and NaBPh 4 for ligand 8; 3-fold for both LiBPh 4 • 3dme and NaBPh 4 for (R,R)-Chiraphite) with virtually no effect on the activity. The facts that (1) no change in the iso/n ratio is observed upon addition of the noncoordinating salt, TBA • BPh 4 , (2) LiBPh 4 • 3dme has little effect on the regioselectivity of an in situ formed rhodium(I) complex of diphos, and (3) the increase in regioselectivity levels out at high salt:Rh ratios suggest the increase in regioselectivity is due to coordination of the alkali metal salt to the oxygen of a carbonyl ligand and to the phosphite oxygens during the regioselectivity-determining step. This proposal is consistent with the observation of only weak 1:1 coordination of LiBPh 4 • 3dme with a model metallacrown ether, cis-Mo(CO) 4 (8) in acetonitrile-d 3 .

Phosphine-substituted oligothiophenes are interesting third-order nonlinear materials. Both their linear and nonlinear optical properties can be altered by varying the group attached to the nonbonding pair of electrons on the phosphorus atoms, the number of phosphine groups attached to the oligothiophene and the number of repeat units in the oligothiophene. In this article, we report the syntheses, multinuclear NMR spectroscopic characterizations and X-ray crystal structures for three derivatives of 5,5 0 -bis(diphenylphosphino)-2,2 0 -bithiophene, Ph 2 (X)P(C 4 H 2 S) 2 P(X)Ph 2 (X ¼ -, 1) in which X is O (2), S (3) and CH 3 þ Á I 7 (4). The X-ray crystal structures exhibit significantly different p-p stacking, suggesting that these compounds could have significantly different nonlinear optical properties in the solid state.

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