The Effect of Stereochemistry on Sodium Ion Complexation in Nucleoside-Metallacarborane Conjugates

Table 2

The main peaks in the ESI mass spectra recorded for negative ions and relative intensity of signals for metallacarborane-2^′-deoxyguanosine conjugates 1–3, and metallacarborane-thymidine conjugates 4–6, at various cone voltages.

		m/z
No	Molecular formula	Cone voltage (cv) [V]
	MW∗	30	50	70	90
1	C18H41N5O6B18Co; MW 677	486 (22%); (M-C)− 552 (100%); (M-A)− 678 (22%); M−	552 (100%); (M-A)− 678 (18%); M−	486 (20%); (M-C)− 552 (20%); (M-A)− 678 (100%); M−	486 (100%); (M-C)^- 552 (20%); (M-A)− 678 (22%); M−
2	C18H41N5O6B18Co; MW 677	678; M−	561 (20%); (M-B)− 678 (100%); M−	561 (40%); (M-B)− 678 (100%); M−	561 (80%); (M-B)− 678 (100%); M−
3	C18H41N5O6B18Co; MW 677	561 (100%); (M-B)− 678 (trace); M−	561; (M-B)− 677 (trace); M−	561; (M-B)− 678 (trace); M−	561; (M-B)− 678 (trace); M−
4	C18H42N2O7B18Co,; MW 652	653; M−	536 (100%); (M-E)− 653 (25%); M−	410 (15%); (M-D)− 536 (80%); (M-E)− 653 (100%); M−	410 (30%); (M-D)− 536 (100%); (M-E)− 653 (25%); M−
5	C18H42N2O7B18Co; MW 652	653; M−	536 (10%); (M-E)− 653 (100%); M−	410 (10%), (M-D)− 536 (60%); (M-E)− 653 (100%); M−	536 (90%); (M-E)− 653 (100%); M−
6	C18H42N2O7B18Co; MW 652	653; M−	410 (10%); (M-D)− 536 (100%); (M-E)− 653 (20%); M−	410 (10%); (M-D)− 536 (20%); (M-E)− 653 (100%); M−	410 (10%); (M-D)− 536 (100%); (M-E)− 653 (20%); M−

∗Calculation of the theoretical molecular mass for compounds 1–6 was performed using option “Analyze Structure” in ChemDraw Program. The calculated masses provided in the manuscript correspond to molecular weight (MW) based on the average mass of the elements consisting natural isotopes.
Where (for 1–3): M⁻𝑚/𝑧=678 (B₁₈C₁₈CoH₄₁N₅O₆), (M-A)⁻𝑚/𝑧=552 (B₁₇C₁₃CoH₃₃N₅O₃), (M-B)⁻𝑚/𝑧=561 (B₁₈C₁₃CoH₃₃N₅O₃), (M-C)⁻𝑚/𝑧=486 (B₉C₁₆H₃₀N₅O₆).
Where (for 4–6): M⁻𝑚/𝑧=653 (B₁₈C₁₈CoH₄₂N₂O₇), (M-D)− 𝑚/𝑧=410 (B₁₈C₈CoH₂₉O₂), (M-E)⁻𝑚/𝑧=536 (B₁₈C₁₃CoH₃₄N₂O₄).