Table 2.

The ¹H-NMR chemical shifts of bridging protons in various isotopologs of homotrimers and heterotrimers of POOH-containing acids 1–4 in CDF₃/CDF₂Cl at 100 K. The corresponding spectra are shown in Figure 3, Figure 5, Figure 7, Figure 9 and Figure 10 and Figures S1, S3, S5, S8, and S9.

Complex	HHH	HHD	HDH	HDD	HHH	HDH	DDH
1-1-1a	-	-	-	-	14.45	14.28	14.11
2-2-2b	-	-	-	-	13.96	13.72	13.54
3-3-3c	-	-	-	-	n.d. d	n.d.	n.d.
4-4-4a	-	-	-	-	13.76	13.54	13.38
1-2-1	14.53	14.70	14.22	14.43	14.71	14.41	14.12
2-1-2	14.46	14.66	14.14	14.38	14.36	14.04	13.74
1-3-1	15.74	n.m. e	n.m.	n.m.	16.98	n.m.	n.m.
3-1-3	15.94	n.m.	n.m.	n.m.	15.98	n.m.	n.m.
1-4-1	14.70	15.44	14.67	15.75	16.83	16.97	16.78
4-1-4	14.43	15.07	14.46	15.48	16.76	16.94	16.74
2-3-2	14.98	15.02	14.64	14.75	14.29	13.97	13.62
3-2-3	14.72	14.75	14.40	14.48	15.39	n.d.	n.d.
2-4-2	14.80	n.m.	n.m.	n.m.	15.04	n.m.	n.m.
4-2-4	14.81	n.m.	n.m.	n.m.	14.88	n.m.	n.m.
3-4-3	14.50	n.d.	n.d.	n.d.	15.24	n.d.	n.d.
4-3-4	14.61	14.67	14.34	14.44	13.83	13.55	13.30

^a—chemical shifts coincide with those reported previously in reference [15]. ^b—chemical shifts coincide with those reported previously in reference [14]. ^c—the diphenylphosphinic acid 3 is poorly soluble in CDF₃/CDF₂Cl and does not form self-associates in a detectable amount. ^d—n.d.—not detected. ^e—n.m.—not measured.