ACCEPTED MANUSCRIPT
42.7 and 42.5 (C(CH3)2Ph), 33.0, 32.7, 31.6, 31.6, 31.5, 31.5, 26.1 and 26.0 (C(CH3)2Ph), 25.9 and 25.8
(CH(CH3)2). 51V NMR (79 MHz, C6D6, ppm): δ -563.4. FT-IR (KBr, cm−1): ν(V=O) 801. EA calcd. for
C55H65N2O4V 0.6(CH2Cl2): C, 72.59; H, 7.25; N, 3.04. Found: C, 72.54; H, 7.44; N, 3.10. ESI-MS (CH3CN): m/z =
809.53 [VVO(L1)]+, ca. 70%; 849.86 (M+), 100%; 1636.13 {[VVO(L1)]2O}+, ca. 20%.
Synthesis of [VO(L1)Cl], 2
1 (0.608 g, 0.7 mmol) was suspended in 10 mL of CH2Cl2 and three equivalents of SiMe3Cl (0.179 g, 2.1 mmol)
were added dropwise at room temperature. The mixture was stirred for 18 h to give a dark violet solution. The
solvent was evaporated to dryness under vacuum to give a dark violet powder that was recrystallized from n-
hexane at -20 °C (0.355 g, 60 % yield. 1H NMR (300 MHz, C6D6, ppm): δ 7.61 (s, 1H, CH-Ar), 7.46-7.31 (m, 7H,
CH-Ar), 7.25-7.17 (m, 6H, CH-Ar), 7.10-7.04 (m, 2H, CH-Ar), 6.97-6.89 (m, 2H, CH-Ar), 6.87-6.64 (m, 5H, CH-
Ar), 6.58-6.53 (m, 1H, CH-Ar), 4.92 (d, 2JHH = 14.1 Hz, 1H, NCH2Ar), 4.52 (d, 2JHH = 13.7 Hz, 1H, NCH2Ar), 3.08
2
2
(d, JHH = 14.5 Hz, 1H, NCH2Ar), 2.84 (d, JHH = 14.5 Hz, 1H, NCH2Ar), 2.10 (s, 3H, C(CH3)2Ph), 2.05 (s, 3H,
C(CH3)2Ph), 1.79 (s, 3H, C(CH3)2Ph), 1.77 (s, 3H, C(CH3)2Ph), 1.70 (s, 3H, C(CH3)2Ph), 1.68 (s, 3H, C(CH3)2Ph),
1.49 (s, 3H, C(CH3)2Ph), 1.36 (m, 1H, N(CH2)2N), 1.36 (s, 3H, C(CH3)2Ph), 1.32 (m, 2H, N(CH2)2N), 1.18 (m, 1H,
N(CH2)2N). 13C-{1H} NMR (101 MHz, C6D6, ppm): δ 162.1, 159.0, 154.4, 153.8, 150.9, 146.0, 141.8, 137.5 and
136.3 (Cipso-Ar), 128.6, 128.5, 127.2, 127.1, 126.7, 126.5, 126.3, 126.2, 126.1, 124.4, 124.1, 123.8 and 123.3
(CH-Ar), 119.2 (Cipso-Ar), 57.8 and 52.0 (NCH2Ar), 47.1 and 44.3 (N(CH2)2N), 43.2, 43.0, 42.8 and 42.6
(C(CH3)2Ph), 32.7, 32.6, 31.6, 31.3, 26.6 and 26.1 (C(CH3)2Ph). 51V NMR (79 MHz, C6D6, ppm): δ -413. FT-IR
(KBr, cm−1): ν(V=O) 802. EA calcd. for C52H58ClN2O3V 2.8(CH2Cl2): C, 60.76; H, 5.92; N, 2.59. Found: C, 60.61;
H, 6.33; N, 2.56. ESI-MS (CH3CN): m/z = 843.01 (M–), 100%; 878.58 {[VVO(L1)(Cl)]Cl}–, ca. 45%; 905.65
{[VVO2(H2L1)Cl]CH3CN}–, ca. 40%.
Reaction of H2L2 with VO(OiPr)3
A THF solution of VO(OiPr)3 (0.122 g, 0.5 mmol) was added dropwise to a solution of H2L2 (0.318 g, 0.5 mmol) in
the same solvent, at room temperature. The initially colorless solution turned to dark blue and, after being stirred
for 18 h, it was evaporated to dryness to give a blue crystalline powder. A THF solution of the powder at -20 ºC
gave green crystals of 4 suitable for X-ray diffraction. The NMR analysis of the remaining solid revealed the
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presence of H2L2 and [VO(L2)(OiPr)], 3, in 1:4 ratio. Data for 3: H NMR (300 MHz, CDCl3, ppm): δ 8.29 (s, 1H,
N=CH), 8.14 (s, 1H, N=CH), 7.56 (s, 2H, CH-Ar), 7.40-7.14 (m, 4H, CH-Ph), 7.07 (2H, CH-Ar), 7.04-6.93 (m, 4H
CH-Ph), 6.57 (m, 2H, CH-Ph), 6.35 (d, J = 6.0 Hz, 1H, NCH), 6.20 (sept, 3JHH = 6.0 Hz, 1H, OCH(CH3)2), 5.03 (d,
3JHH = 6.0 Hz, 1H, NCH), 1.61 (s, 9H, C(CH3)3), 1.48 (s, 9H, C(CH3)3), 1.44 (d, 3H, CH(CH3)2), 1.30 (s, 9H,
C(CH3)3), 1.26 (s, 9H, C(CH3)3), 1.24 (d, 3H, CH(CH3)2). 13C-{1H} NMR (101 MHz, C6D6, ppm): δ 167.0 (N=CH),
166.8 (Cipso-Ar), 160.7 (N=CH), 158.1, 141.3, 139.4, 138.9, 138.4 and 132.3 (Cipso-Ar), 132.1 (CH-Ph), 130.44
(CH-Ar), 129.6 (CH-Ph), 129.2, 129.0 and 128.9 (CH-Ar), 128.54, 128.45, 128.4, 128.3, 128.2 and 125.7 (CH-
Ph), 122.3 and 121.8 (Cipso-Ph), 89.6 (CH(CH3)2), 76.1 and 75.4 (NCH), 35.69, 35.68, 34.4 and 34.3 (C(CH3)3),
31.6, 31.5, 30.5 and 30.2 (C(CH3)3), 26.6 and 26.4 (CH(CH3)2). 51V NMR (79 MHz, C6D6, ppm): δ –480. ESI-MS
(CH3CN): m/z = 709.70 [VVO(L1)]+, 100%.
Synthesis of [VO(L2)], 4
H2L2 (0.432 g, 0.67 mmol) in EtOH was added to an aqueous solution 50 % (w/v) of VOCl2·2H2O (0.18 mL, 0.67
mmol) and the mixture was stirred for 0.5 h at room temperature leading to a green/grey solution. Addition of a
solution of NaOH 1M in water till pH ~ 8 led to the formation of a light green precipitate that was separated by
filtration and dried in vacuum (0.290 g, 61%). EPR (DMF, 77 K): gz= 1.949, Az= 160.6 × 10-4 cm-1. Elemental
analysis: Calcd. for C44H54N2O3V 0.8(H2O); C, 72.97; H, 7.74; N, 3.87; Found: C, 72.96; H, 7.24; N, 3.82.
Reaction of H2L3 with VO(OiPr)3
A THF solution of VO(OiPr)3 (0.122 g, 0.5 mmol) was added dropwise to a solution of H2L3 (0.406 g, 0.5 mmol) in
the same solvent, at room temperature. The initially colorless solution turned to dark blue and, after 18 h, it was
evaporated to dryness to give a blue crystalline powder. The NMR analysis of the powder revealed the presence
of several species including H2L3, [VO(L3)(OiPr)] and (µ-O){[VO(OiPr)(µ-O)(L3)VO]}2,5. An Et2O solution of the
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mixture at -20 ºC gave blue crystals of 5 in 30% yield, suitable for X-ray diffraction. Data for 5: H NMR (300
MHz, C6D6, ppm): δ 9.25 (d, J = 8.5 Hz, 1H, CH-Ar), 8.48 (d, J = 8.4 Hz, 1H, CH-Ar), 8.34 (d, J = 8.5 Hz, 1H, CH-
Ar), 7.88 (s, 1H, N=CH), 7.76 (s, 1H, CH-Ar), 7.69 (s, 1H, N=CH), 7.58 (s, 2H, CH-Ar), 7.36-7.18 (m, 4H, CH-Ar),
3
7.04-6.86 (m, 3H CH-Ar), 6.81 (d, J = 8.5 Hz, 2H, CH-Ar), 6.62 (s, 1H, CH-Ar), 4.41 (sept, JHH = 6.1 Hz, 2H,
OCH(CH3)2), 2.19 (s, 18H, C(CH3)3), 1.72 (s, 9H, C(CH3)3), 1.29 (s, 9H, C(CH3)3), 1.04 (s, 9H, C(CH3)3), 0.88 (d,
6H, CH(CH3)2), 0.39 (d, 6H, CH(CH3)2). 13C-{1H} NMR (101 MHz, C6D6, ppm): δ 168.0 and 166.2 (Cipso-Ar), 165.7