Table 3.

UV-Vis properties of 2•O₂X, 3•O₂X and 3′•O₂X in CH₂Cl₂.

O2X	λmax (nm), [ε] (M−1 cm−1)
	2•O2X	3•O2X	3′•O2X
O2AsMe2	632 [2100]	-- a	-- b
O2PMe2	674 [1800]	-- a	616 [2400]
O2PPh2	678 [2100]	621 [1800]	592 [2600]
O2P(OPh)2	680 [2800]	576 [3100]	594 [3600]
O2CCPh3	708 [2500]	630 [2200]	595 [3300]
O2CCMe3	706 [--] c	580 [3100]	577 [3800]
O2CPh	704 [--]c	588 [1500]d	592 [2300]
O2CC6H2-3,4,5-(OMe)3	707 [2600]	590 [3200]	592 [4300]
O2CC6H3-3,4-(OMe)2	704 [--]c	578 [6200]	590 [5300]
O2CC6H3-3,5-(OMe)2	706 [--]c	588 [5400]	592 [5600]
O2CC6H4-4-OMe	705 [--]c	580 [3000]	590 [4000]

^aConversion to 3•O₂X did not take place at any temperature.

^bConversion to 3′•O₂X did not take place at any temperature even with addition of 100 equivalents of OPPh₃.

^cConversion of 2•O₂X to 3•O₂X began before complete formation of 2•O₂X, so ε was not determined.

^dValues from reference 42.