Hydrolysis of Methionine- and Histidine-Containing Peptides Promoted by Dinuclear Platinum(II) Complexes with Benzodiazines as Bridging Ligands: Influence of Ligand Structure on the Catalytic Ability of Platinum(II) Complexes

Table 1

NMR (¹H and ¹³C) chemical and coordination shifts (δ, ppm), alongside multiplicities and coupling constants (J_H-H, Hz), for the N-heterocyclic ligands and the corresponding dinuclear platinum(II) complexes 1–3 in D₂O as a solvent with TSP as the internal standard.

Atom position	^1H		^13C
	qx	1	qx	1
2,3	8.44, s	9.59, s (+1.15)	145.67	151.77 (+6.10)
5,8	7.51, m	9.73, dd, J = 6.7; 3.3 Hz (+2.22)	131.94	135.93 (+3.99)
6,7	7.51, m	8.41, dd, J = 6.7; 3.3 Hz (+0.90)	128.83	130.09 (+1.26)
4a,8a	—	—	141.85	145.26 (+3.41)
	qz	2	qz	2
2	9.09, s	10.12, d, J = 11.0 Hz (+1.03)	163.39	178.11 (+14.72)
4	8.84, s	9.52, d, J = 8.8 Hz (+0.68)	156.05	168.56 (+12.51)
5	7.80, m	8.51, m	129.07	130.14 (+1.07)
8		(+0.71)	131.53	132.81 (+1.28)
6	7.79, m	8.16, m	130.60	135.11 (+4.51)
7		(+0.37)	138.42	143.10 (+4.68)
4a	—	—	126.98	128.58 (+1.60)
8a	—	—	150.76	152.39 (+1.63)
	phtz	3	phtz	3
1,4	9.18, s	10.05, s (+0.87)	154.27	164.32 (+10.05)
6,7	7.88, m	8.40, m (+0.52)	136.61	140.50 (+3.89)
5,8	7.88, m	8.40, m (+0.52)	129.38	131.04 (+1.66)
4a,8a	—	—	129.04	130.96 (+1.92)

The aliphatic methylene protons of the bidentatedly coordinated en ligand in 1–3 give a singlet in the region 2.78–2.84 ppm, while the resonance for the corresponding carbon atoms is in the region 49.42–51.27 ppm. s = singlet; d = doublet; dd = doublet of doublets; m = multiplet.