Journal of the American Chemical Society, , vol. 54, p. 4680 Journal of the American Chemical Society, , vol. 62, p. 2448 Bulletin de la Societe Chimique de France, , vol. <5>6, p. 1210 Journal of the American Chemical Society, , vol. 53, p. 1093 Journal of the American Chemical Society, , vol. 54, p. 4680