Compound characterization data

Yang Liu, Jan C. Kruse, Andreas A. Lang, Gábor Balázs, Robert Wolf. “Iron-digermanium cluster: synthesis, Lewis-base-induced isomerization, dihydrogen activation, and alkene cycloaddition.” ChemRxiv (2026). https://doi.org/10.26434/chemrxiv.15004317/v3

Lone terminal reaction-conversion outcomes were not retained

[Fe(GeAr’)2]
Identifier	1
¹H NMR (500 MHz, C₆D₆, 298 K)	δ (ppm) 0.44 (d, J = 6.9 Hz, 6H, −CH(CH3)2 of η6-Dipp), 0.95 (d, J = 6.9 Hz, 6H, −CH(CH3)2), 1.05 (d, J = 6.8 Hz, 6H, −CH(CH3)2 of η6-Dipp), 1.12 (d, J = 6.8 Hz, 12H, −CH(CH3)2), 1.21 (d, J = 6.9 Hz, 6H, −CH(CH3)2), 1.27 (d, J = 7.0 Hz, 12H, −CH(CH3)2), 2.27 (sept, J = 7.0 Hz, 2H, −CH(CH3)2 of η6-Dipp), 2.96 (sept, J = 7.0 Hz, 2H, −CH(CH3)2), 3.01 (sept, J = 7.0 Hz, 4H, −CH(CH3)2), 4.56 (d, J = 6.5 Hz, 2H, m-CH-η6-Dipp), 5.32 (t, J = 6.5 Hz, 1H, p-CH-η6-Dipp), 7.02–7.06 (m, 3H), 7.10–7.13 (m, 1H), 7.14 (d, J = 7.5 Hz, 2H), 7.23 (d, J = 8.0 Hz, 2H), 7.26 (t, J = 7.5 Hz, 1H), 7.32 (t, J = 7.0 Hz, 1H), 7.36 (t, J = 7.5 Hz, 1H), 7.40 (dd, J = 7.5, 1.5 Hz, 1H), 7.78 (dd, J = 7.5, 1.5 Hz, 1H)
¹³C{¹H} NMR (125 MHz, C₆D₆, 298 K)	δ (ppm) 169.6 (Cipso–Ge), 158.0 (Cipso–Ge), 147.3 (o-C-Dipp), 146.6 (o-C-Dipp), 145.8 (o-C-Dipp), 144.7 (o-C-Dipp), 143.4 (o-C-Dipp), 142.2 (Dipp-C-Ar), 138.4 (Dipp-C-Ar), 129.4, 129.3, 129.2, 129.0, 128.5, 128.0, 126.5, 123.5 (m-C-Dipp), 122.6 (m-C-Dipp), 115.8 (η6-Dipp-C-Ar), 111.4 (o-C-η6-Dipp), 84.2 (p-C-η6-Dipp), 78.6 (m-C-η6-Dipp), 31.4 (−CH(CH3)2), 31.1 (−CH(CH3)2), 28.6 (−CH(CH3)2), 25.8 (−CH(CH3)2), 25.7 (−CH(CH3)2), 24.8 (−CH(CH3)2), 24.7 (−CH(CH3)2), 24.5 (−CH(CH3)2), 23.8 (−CH(CH3)2)
NMR observations	Due to overlapping signals in the aromatic region, the full assignment of the signals of the aryl rings was not possible. Signals of two H atoms on aryl rings overlap with the residual solvent peak of C₆D₆
Elemental analysis	Calcd. for C₆₀H₇₄Ge₂Fe·0.5C₆H₆: C 73.08, H 7.50; Found: C 73.03, H 7.62
UV–vis (toluene, 298 K)	λmax, nm (ε, M⁻¹ cm⁻¹) 380 (10700), 500 (shoulder, 1780), 600 (broad, 750), 780 (broad, 250)

[(tBuNC)Fe(GeAr’)2]
Identifier	2
¹H NMR (500 MHz, C₆D₆, 298 K)	δ (ppm) 0.44 (d, J = 6.9 Hz, 6H, −CH(CH3)2 of η6-Dipp), 0.89 (d, J = 6.7 Hz, 6H, −CH(CH3)2), 1.09 (d, J = 6.7 Hz, 6H, −CH(CH3)2 of η6-Dipp), 1.12 (d, J = 6.9 Hz, 6H, −CH(CH3)2), 1.17 (d, J = 6.8 Hz, 6H, −CH(CH3)2), 1.23 (d, J = 6.9 Hz, 6H, −CH(CH3)2), 1.27 (s, 9H, −C(CH3)3), 1.40 (d, J = 6.7 Hz, 6H, −CH(CH3)2), 1.51 (d, J = 6.7 Hz, 6H, −CH(CH3)2), 2.73 (sept, J = 7.0 Hz, 2H, −CH(CH3)2 of η6-Dipp), 2.85 (sept, J = 7.0 Hz, 2H, −CH(CH3)2), 2.98 (sept, J = 7.0 Hz, 2H, −CH(CH3)2), 3.55 (sept, J = 7.0 Hz, 2H, −CH(CH3)2), 4.35 (d, J = 6.5 Hz, 2H, m-CH-η6-Dipp), 4.76 (t, J = 6.5 Hz, 1H, p-CH-η6-Dipp), 6.91 (dd, J = 7.5, 1.5 Hz, 2H), 7.02–7.06 (m, 3H), 7.15 (dd, J = 7.5, 1.5 Hz, 2H), 7.21 (d, J = 8.0 Hz, 3H), 7.28 (dd, J = 7.5, 1.5 Hz, 1H), 7.36–7.44 (m, 3H)
¹³C{¹H} NMR (125 MHz, C₆D₆, 298 K)	δ (ppm) 169.0, 164.3, 153.6, 147.5, 146.8, 146.7, 145.5, 145.4, 141.5, 140.6, 140.1, 129.6, 129.3, 128.3, 128.0, 126.7, 125.9, 123.6, 123.4, 123.1, 109.9 (η6-Dipp-C-Ar), 107.9 (o-C-η6-Dipp), 89.2 (p-C-η6-Dipp), 85.6 (m-C-η6-Dipp), 57.1 (tBuNC), 31.4 (−C(CH3)3), 31.3 (−CH(CH3)2), 30.8 (−CH(CH3)2), 30.1 (−CH(CH3)2), 29.7 (−CH(CH3)2), 27.0 (−CH(CH3)2), 26.1 (−CH(CH3)2), 25.7 (−CH(CH3)2), 25.5 (−CH(CH3)2), 25.1 (−CH(CH3)2), 24.0 (−CH(CH3)2), 23.9 (−CH(CH3)2), 19.8 (−CH(CH3)2)
NMR observations	Due to overlapping signals in the aromatic region, the full assignment of the signals of the aryl rings was not possible. Signals of one H atom on aryl rings overlap with the residual solvent peak of C₆D₆
Elemental analysis	Calcd. for C₆₅H₈₃NGe₂Fe: C 72.32, H 7.75, N 1.30; Found: C 72.44, H 7.59, N 1.19
UV–vis (toluene, 298 K)	λmax, nm (ε, M⁻¹ cm⁻¹) 370 (shoulder, 19400), 420 (shoulder, 12460), 470 (shoulder, 6950), 590 (1460), 790 (2200)
ATR−IR (powder, cm⁻¹)	ν = 2025 (NC)

[(Ar’GeH2)Fe(GeAr’)]
Identifier	3
¹H NMR (500 MHz, C₆D₆, 298 K)	δ (ppm) 0.97 (d, J = 6.8 Hz, 6H, −CH(CH3)2 of η6-Dipp-Fe), 1.07 (d, J = 6.8 Hz, 12H, −CH(CH3)2), 1.13 (d, J = 6.9 Hz, 6H, −CH(CH3)2 of η6-Dipp-Fe), 1.18 (d, J = 6.8 Hz, 6H, −CH(CH3)2), 1.45 (d, J = 7.2 Hz, 12H, −CH(CH3)2), 1.46 (d, J = 7.5 Hz, 6H, −CH(CH3)2), 2.23 (sept, J = 7.0 Hz, 2H, −CH(CH3)2 of η6-Dipp-Fe), 2.81 (sept, J = 7.0 Hz, 4H, −CH(CH3)2), 2.88 (sept, J = 7.0 Hz, 2H, −CH(CH3)2), 3.14 (s, 2H, −GeH), 5.34–5.45 (m, 3H, m- and p-CH-η6-Dipp-Fe), 6.81 (d, J = 7.5 Hz, 2H, m-Ar’H), 7.18–7.23 (m, 6H), 7.38 (d, J = 7.5, 2H, m-Ar’H), 7.50 (t, J = 7.5 Hz, 1H)
¹³C{¹H} NMR (125 MHz, C₆D₆, 298 K)	δ (ppm) 163.0, 154.7, 147.9, 147.0, 146.9, 145.0, 142.8, 140.5, 136.1, 130.5, 128.9, 128.3, 128.1, 127.8, 127.2, 125.5, 124.1, 122.7, 115.6, 107.8, 78.3 (m-C-η6-Dipp), 76.7 (p-C-η6-Dipp), 31.2 (−CH(CH3)2), 31.1 (−CH(CH3)2), 28.9 (−CH(CH3)2), 25.9 (−CH(CH3)2 of η6-Dipp), 25.8 (−CH(CH3)2), 25.3 (−CH(CH3)2), 23.63 (−CH(CH3)2), 23.60 (−CH(CH3)2), 23.5 (−CH(CH3)2 of η6-Dipp)
NMR observations	Due to overlapping signals in the aromatic region, the full assignment of the signals of the aryl rings was not possible. Signals of four H atoms on aryl rings overlap with the residual solvent peak of C₆D₆
Elemental analysis	Calcd. for C₆₀H₇₆Ge₂Fe·C₆H₆: C 73.64, H 7.68; Found: C 73.34, H 7.33
UV–vis (toluene, 298 K)	λmax (nm) 420 (strong), 530, 630 (broad)
UV–vis observation	The poor solubility of 3 in toluene prevented accurate determination of its concentration; therefore, the absorption coefficient was not calculated
ATR−IR (powder, cm⁻¹)	ν = 2002 (GeH)

[(Ar’GeCH2(Ph)CHGeAr’)Fe]
Identifier	4a
¹H NMR (400 MHz, d₈-THF, 268 K)	δ (ppm) −0.60 (dd, J = 13.9, 8.2 Hz, 1H, PhCH), 0.00 (d, J = 6.7 Hz, 3H, −CH(CH3)2), 0.34 (d, J = 6.9 Hz, 3H, −CH(CH3)2), 0.38 (d, J = 14.0 Hz, 1H, −CH2CHPh), 0.59 (d, J = 6.7 Hz, 3H, −CH(CH3)2), 0.65 (d, J = 7.0 Hz, 3H, −CH(CH3)2), 0.77 (d, J = 6.7 Hz, 3H, −CH(CH3)2), 0.85 (d, J = 6.9 Hz, 3H, −CH(CH3)2), 0.88 (d, J = 6.9 Hz, 6H, −CH(CH3)2), 0.96 (d, J = 6.8 Hz, 6H, −CH(CH3)2), 1.10 (d, J = 6.7 Hz, 3H, −CH(CH3)2), 1.14 (d, J = 7.0 Hz, 3H, −CH(CH3)2), 1.16 (d, J = 7.0 Hz, 3H, −CH(CH3)2), 1.19 (d, J = 6.9 Hz, 3H, −CH(CH3)2), 1.35 (d, J = 6.9 Hz, 3H, −CH(CH3)2), 1.51 (d, J = 6.9 Hz, 3H, −CH(CH3)2), 1.82 (sept, J = 6.8 Hz, 1H, −CH(CH3)2), 2.19 (sept, J = 6.8 Hz, 1H, −CH(CH3)2), 2.30 (sept, J = 6.8 Hz, 1H, −CH(CH3)2), 2.58 (sept, J = 6.8 Hz, 1H, −CH(CH3)2), 2.64 (sept, J = 6.8 Hz, 1H, −CH(CH3)2), 2.95 (sept, J = 6.8 Hz, 1H, −CH(CH3)2), 3.35 (sept, J = 6.8 Hz, 1H, −CH(CH3)2), 3.48 (sept, J = 6.8 Hz, 1H, −CH(CH3)2), 3.58 (d, J = 13.9 Hz, 1H, −CH2CHPh), 3.64 (d, J = 5.9 Hz, 1H, m-CH-η6-Dipp), 4.56 (d, J = 5.8 Hz, 1H, m-CH-η6-Dipp), 4.97 (t, J = 5.9 Hz, 1H, p-CH-η6-Dipp), 6.18 (d, J = 7.2 Hz, 2H), 6.18 (d, J = 7.2 Hz, 2H), 6.60–6.66 (m, 1H), 6.66–6.74 (m, 3H), 6.78 (d, J = 7.6 Hz, 1H), 7.01–7.08 (m, 2H), 7.08–7.17 (m, 3H), 7.17–7.26 (m, 2H), 7.30 (d, J = 8.0 Hz, 1H) 7.33–7.40 (m, 2H), 7.46 (t, J = 7.5 Hz, 1H), 7.50 (d, J = 7.7 Hz, 1H), 7.55 (t, J = 7.5 Hz, 1H)
¹³C{¹H} NMR (100 MHz, d₈-THF, 268 K)	δ (ppm) 168.2, 161.0, 149.1, 148.2, 147.8, 147.5, 146.9, 146.8, 146.4, 145.6, 143.4, 142.4, 142.0, 141.6, 139.5, 131.5, 131.0, 129.2, 129.0, 128.8, 128.7, 127.9, 127.9, 127.5, 127.3, 124.2, 124.1, 123.5, 123.3, 123.2, 122.9, 122.8, 117.1, 117.0, 104.5, 82.9, 79.7, 75.7, 57.7, 37.1, 32.4, 31.9, 31.4, 31.3, 30.8, 30 .8, 30.8, 28.0, 27.1, 26.5, 25.8, 25.4, 25.6, 25.5, 25.4, 25.0, 24.9, 24.5, 24.3, 24.1, 23.8, 23.3, 22.8, 21.1
NMR observation	Due to overlapping signals in the aromatic region, the full assignment of the signals of the aryl rings was not possible
Elemental analysis	Calcd. for C₆₈H₈₂Ge₂Fe: C 74.22, H 7.51; Found: C 74.35, H 7.16
UV–vis (toluene, 298 K)	λmax, nm (ε, M⁻¹ cm⁻¹) 400 (shoulder, 8630), 450 (14700), 600 (broad, 1830)

[(Ar’GeCH2(CH3)CC(CH3)CH2GeAr’)Fe]
Identifier	5
¹H NMR (400 MHz, d₈-THF, 223 K)	δ (ppm) 0.69 (d, J = 6.8 Hz, 6H, −CH(CH3)2), 0.75 (d, J = 7.0 Hz, 3H, −CH(CH3)2), 0.85–1.01 (m, 15H), 1.03 (d, J = 6.6 Hz, 3H, −CH(CH3)2), 1.11 (d, J = 6.8 Hz, 3H, −CH(CH3)2), 1.13–1.23 (m, 15H), 1.24–1.29 (d+s, 6H, −CH(CH3)2 and -C(CH3)CH2Ge), 1.30–1.38 (m, 4H), 1.54 (d, J = 13.7 Hz, 1H, -C(CH3)CH2Ge), 1.58 (d, 6.9 Hz, 3H, −CH(CH3)2), 1.62–1.72 (m, H), 1.90 (d, J = 12.9 Hz, 1H, -C(CH3)CH2Ge), 2.07 (sept, J = 6.8 Hz, 1H, −CH(CH3)2), 2.67 (sept, J = 6.8 Hz, 1H, −CH(CH3)2), 2.79 (sept, J = 6.8 Hz, 2H, −CH(CH3)2), 3.00 (sept, J = 6.8 Hz, 1H, −CH(CH3)2), 3.15 (sept, J = 6.8 Hz, 1H, −CH(CH3)2), 3.66 (sept, J = 6.8 Hz, 1H, −CH(CH3)2), 3.82 (d, J = 5.9 Hz, 1H, m-CH-η6-Dipp-Fe), 4.41 (t, J = 5.8 Hz, 1H, p-CH-η6-Dipp-Fe), 5.04 (d, J = 5.9 Hz, 1H, m-CH-η6-Dipp-Fe), 6.98 (dd, J = 6.2, 2.9 Hz, 1H, m-CH of Ar’), 7.08 (d, J = 7.5 Hz, 1H, m-CH of Dipp), 7.15–7.31 (m, 7H), 7.31–7.37 (m, 1H), 7.37–7.48 (m, 3H), 7.50 (t, J = 6.9 Hz, 2H, p-CH of Dipp), 7.90 (d, J = 7.4 Hz, 1H, m-CH of Ar’)
¹³C{¹H} NMR (100 MHz, d₈-THF, 223 K)	δ (ppm) δ 169.3, 166.1, 148.6, 147.3, 147.2, 147.0, 146.8, 146.8, 144.2, 143.6, 143.1, 143.1, 142.5, 140.9, 139.4, 131.7, 130.9, 129.9, 129.9, 129.1, 128.7, 128.7, 127.3, 127.1, 126.6, 124.5, 123.6, 123.6, 123.4, 122.8, 120.9, 117.8, 116.4, 108.9, 82.5, 78.6, 75.3, 54.9, 41.5, 32.0, 31.9, 31.3, 31.2, 31.1, 31.0, 30.5, 29.9, 27.8, 26.8, 26.4, 26.3, 26.2, 26.0, 24.6, 24.5, 24.2, 23.9, 23.7, 23.5, 22.8, 21.9, 21.6
NMR observations	Residual n-pentane signals account for approximately three protons by integration overlap with the −CH(CH3)2 signals, resulting in an apparent proton count higher than expected for 5. Due to signal overlap in the aromatic and alkyl regions, full assignment of the resonances was not possible
Elemental analysis	Calcd. for C₆₆H₈₄Ge₂Fe: C 73.50, H 7.85; Found: C 73.47, H 7.87
UV–vis (toluene, 298 K)	λmax, nm (ε, M⁻¹ cm⁻¹) 330 (shoulder, 7860), 450 (11680), 600 (broad, 3900)

[(Ar’(CH2(CH3)CC(CH3)CH2)GeFe(GeAr’)]
Identifier	6
¹H NMR (500 MHz, C₆D₆, 298 K)	δ (ppm) 0.71 (d, J = 16 Hz, 2H, C(CH3)CH2)Ge), 1.057 (d, J = 7.0 Hz, 6H, −CH(CH3)2 of η6-Dipp), 1.063 (d, J = 7.0 Hz, 12H, −CH(CH3)2), 1.17 (d, J = 7.0 Hz, 6H, −CH(CH3)2), 1.40 (d, J = 7.0 Hz, 12H, −CH(CH3)2), 1.42 (d, J = 7.0 Hz, 6H, −CH(CH3)2), 1.53 (s, 6H, C(CH3)CH2)Ge), 2.04 (d, J = 15.5 Hz, 2H, C(CH3)CH2)Ge), 2.25 (sept, J = 7.0 Hz, 2H, −CH(CH3)2 of η6-Dipp), 2.97 (sept, J = 7.0 Hz, 4H, −CH(CH3)2), 3.00 (sept, J = 7.0 Hz, 2H, −CH(CH3)2), 5.02 (t, J = 6.0 Hz, 1H, p-CH-η6-Dipp), 5.44 (d, J = 6.1 Hz, 2H, m-CH-η6-Dipp), 6.76 (d, J = 7.5 Hz, 2H, m-CH of Ar’), 7.09 (t, J = 7.5 Hz, 1H, p-CH of Ar’), 7.12–7.15 (m, 3H), 7.21 (d, J = 7.8 Hz, 4H, m-CH of Dipp), 7.26 (d, J = 7.7 Hz, 2H, m-CH of Dipp), 7.30–7.37 (m, 3H)
¹³C{¹H} NMR (100 MHz, C₆D₆, 298 K)	δ (ppm) 166.5, 158.2, 147.6, 146.5, 144.4, 143.7, 142.2, 141.0, 138.3, 131.7, 131.6, 129.9, 129.7, 127.93, 127.91, 125.8, 125.7, 123.7, 122.7, 117.0, 108.2, 79.2 (p-C-η6-Dipp), 78.9 (m-C-η6-Dipp), 40.5 (C(CH3)CH2)Ge), 31.1 (−CH(CH3)2), 30.9 (−CH(CH3)2), 29.1 (−CH(CH3)2 of η6-Dipp), 26.3 (−CH(CH3)2), 26.1 (−CH(CH3)2), 24.8 (−CH(CH3)2 of η6-Dipp), 24.0 (−CH(CH3)2), 23.9 (−CH(CH3)2 and C(CH3)CH2)Ge, overlap), 20.3 (−CH(CH3)2)
Elemental analysis	Calcd. for C₆₆H₈₄Ge₂Fe·C₇H₈: C 74.90, H 7.92; Found: C 74.89, H 7.85
UV–vis (toluene, 298 K)	λmax, nm (ε, M⁻¹ cm⁻¹) 350 (13600), 430 (shoulder, 6360), 600 (broad, 700), 680 (broad, 550), 820 (shoulder, 320)

[(Ar’(CH2(CH3)CC(CH3)CH2)SnFe(SnAr’)]
Identifier	7
¹H NMR (500 MHz, C₆D₆, 298 K)	δ (ppm) 0.81 (d, J = 15.7 Hz, 2H, C(CH3)CH2)Sn), 0.99–1.12 (m, 30H, −CH(CH3)2), 1.31–1.44 (m, 18H, −CH(CH3)2), 1.65–1.76 (m, 8H, C(CH3)CH2)Sn + C(CH3)CH2)Sn), 2.27 (sept, J = 7.0 Hz, 2H, −CH(CH3)2 of η6-Dipp), 2.95 (sept, J = 7.0 Hz, 4H, −CH(CH3)2), 3.05 (sept, J = 7.0 Hz, 2H, −CH(CH3)2), 5.51 (d, J = 5.8 Hz, 2H, m-CH-η6-Dipp), 5.63 (t, J = 5.8 Hz, 1H, p-CH-η6-Dipp), 6.91 (d, J = 7.5 Hz, 2H, m-CH of Ar’), 7.18–7.30 (m, 10H), 7.33 (t, J = 7.7 Hz, 2H, p-CH of Dipp), 7.38 (t, J = 7.7 Hz, 1H, p-CH of Ar’)
¹³C{¹H} NMR (125 MHz, C₆D₆, 298 K)	δ (ppm) 179.2, 156.7, 147.7, 146.7, 146.5, 144.9, 142.7, 141.4, 137.9, 132.3, 130.2, 130.1, 129.9, 128.1, 127.4, 126.2, 125.8, 123.8, 122.6, 116.4, 107.2, 76.9 (p-C-η6-Dipp), 75.7 (m-C-η6-Dipp), 31.3 (C(CH3)CH2)Sn), 30.9 (−CH(CH3)2), 30.8 (−CH(CH3)2), 29.4 (−CH(CH3)2), 26.2 (−CH(CH3)2), 26.0 (−CH(CH3)2), 25.0 (−CH(CH3)2), 24.5 (−CH(CH3)2), 23.5 (−CH(CH3)2), 22.7 (C(CH3)CH2)Sn), 22.2 (−CH(CH3)2)
Elemental analysis	Calcd. for C₆₆H₈₄Sn₂Fe: C 67.72, H 7.23; Found: C 67.63, H 7.02
UV–vis (toluene, 298 K)	λmax, nm (ε, M⁻¹ cm⁻¹) 310 (shoulder, 20190), 380 (20540), 480 (9590), 590 (shoulder, 1520), 690 (shoulder, 960)

Crystalline material
Identifiers	4a, 4b
Composition by ¹H NMR	4a/4b = 100:7

[Fe(GeAr’)2]
Identifier	1
¹H NMR after heating (inert atmosphere, 80 °C, 24 h)	No significant changes observed in the ¹H NMR spectrum

[(Ar’GeH2)Fe(GeAr’)]
Identifier	3
Variable-temperature ¹H NMR (400 MHz, d₈-toluene, 213–298 K)	No obvious changes were observed in the ¹H NMR spectra at low temperatures (213–253 K) on the NMR timescale

Reaction of 1 with styrene
Identifiers	1, 4a, and 4b
¹H NMR monitoring (C₆D₆, within 8 h)	4a:4b approximate ratio 1:0.7

[(Ar’GeCH2(Ph)CHGeAr’)Fe]
Identifier	4a
Variable-temperature ¹H NMR (400/500 MHz, d₈-THF, 298 and 268 K)	Broad resonances corresponding to the Ar′ substituent not coordinated to the Fe center were observed at room temperature. At low temperature (268 K), these resonances became well resolved

[(Ar’GeCH2(CH3)CC(CH3)CH2GeAr’)Fe]
Identifier	5
Variable-temperature ¹H NMR (400 MHz, d₈-THF)	Broad signals were observed at 298 K. At low temperature (223 K), these resonances became well resolved

Reaction of B with DMB
Identifiers	B, DMB, and 7
¹H NMR monitoring (298 K, C₆D₆)	7 is the only new species detected. Upon dissolving single crystals of 7 in C₆D₆ (298 K), ¹H NMR signals corresponding to the starting material B and DMB gradually appear, and an equilibrium is established with a 7:B ratio of 2:1

[Fe(GeAr’)2] solid at 80 K
Identifier	1
Zero-field 57Fe Mössbauer (solid, 80 K)	δ = 0.51 mm s⁻¹, \|ΔEQ\| = 0.69 mm s⁻¹, Γ = 0.33 mm s⁻¹

[Fe(GeAr’)2] crystal
Identifier	1
Method	Single-crystal X-ray diffraction
Crystal refinement	Only half of the formula unit is present in the asymmetric unit, with the other half consisting of symmetry equivalent atoms. The Ge1, Ge2 and Fe1 atoms are disordered with respect to a crystallographic inversion center and each atom was refined at half-occupancy at the two disordered sites. SADI (Fe−Ge and Ge−C) restraints were applied
Empirical formula	C₆₀H₇₄FeGe₂
Formula weight	996.22
Temperature/K	123.00(10)
Crystal system	orthorhombic
Space group	Pccn
a/Å	15.61120(10)
b/Å	20.63320(10)
c/Å	16.20520(10)
α/°	90
β/°	90
γ/°	90
Volume/Å³	5219.84(5)
Z	4
ρcalc g/cm³	1.268
μ/mm⁻¹	3.818
F(000)	2096
Crystal size/mm³	0.152 × 0.124 × 0.085
Radiation	Cu Kα (λ = 1.54184)
2Θ range for data collection/°	7.1 to 150.424
Index ranges	-19 ≤ h ≤ 18, -25 ≤ k ≤ 25, -20 ≤ l ≤ 19
Reflections collected	30464
Independent reflections	5319 [Rint = 0.0177, Rsigma = 0.0130]
Data/restraints/parameters	5319/2/306
Goodness-of-fit on F2	1.105
Final R indexes [I>=2σ (I)]	R1 = 0.0406, wR2 = 0.1051
Final R indexes [all data]	R1 = 0.0432, wR2 = 0.1065
Largest diff. peak/hole / e Å⁻³	0.40/−0.62

[(tBuNC)Fe(GeAr’)2]
Identifier	2
Method	Single-crystal X-ray diffraction
Empirical formula	C₆₅H₈₃FeGe₂N
Formula weight	1079.35
Temperature/K	123.00(10)
Crystal system	monoclinic
Space group	P21/n
a/Å	12.91080(10)
b/Å	22.8398(2)
c/Å	19.6786(2)
α/°	90
β/°	103.2760(10)
γ/°	90
Volume/Å³	5647.75(9)
Z	4
ρcalc g/cm³	1.269
μ/mm⁻¹	3.573
F(000)	2280
Crystal size/mm³	0.079 × 0.054 × 0.037
Radiation	Cu Kα (λ = 1.54184)
2Θ range for data collection/°	6.022 to 150.2
Index ranges	-16 ≤ h ≤ 16, -26 ≤ k ≤ 28, -24 ≤ l ≤ 24
Reflections collected	63719
Independent reflections	11447 [Rint = 0.0439, Rsigma = 0.0234]
Data/restraints/parameters	11447/0/641
Goodness-of-fit on F2	1.089
Final R indexes [I>=2σ (I)]	R1 = 0.0461, wR2 = 0.1410
Final R indexes [all data]	R1 = 0.0496, wR2 = 0.1438
Largest diff. peak/hole / e Å⁻³	1.26/−0.78

[(Ar’GeH2)Fe(GeAr’)]
Identifier	3
Method	Single-crystal X-ray diffraction
Crystal refinement	Only half of the formula unit is present in the asymmetric unit, with the other half consisting of symmetry equivalent atoms. The Ge1, Ge2 and Fe1 atoms are disordered with respect to a crystallographic inversion center and each atom was refined at half-occupancy at the two disordered sites. DFIX (Ge−H 1.5 Å) restraints were applied
Empirical formula	C₆₀H₇₆FeGe₂
Formula weight	998.23
Temperature/K	123.00(10)
Crystal system	orthorhombic
Space group	Pccn
a/Å	15.6429(2)
b/Å	20.6078(3)
c/Å	16.2435(2)
α/°	90
β/°	90
γ/°	90
Volume/Å³	5236.35(12)
Z	4
ρcalc g/cm³	1.266
μ/mm⁻¹	1.45
F(000)	2104
Crystal size/mm³	0.13 × 0.11 × 0.06
Radiation	Mo Kα (λ = 0.71073)
2Θ range for data collection/°	5.016 to 74.016
Index ranges	-20 ≤ h ≤ 26, -33 ≤ k ≤ 33, -27 ≤ l ≤ 27
Reflections collected	85627
Independent reflections	12703 [Rint = 0.0395, Rsigma = 0.0293]
Data/restraints/parameters	12703/3/314
Goodness-of-fit on F2	1.218
Final R indexes [I>=2σ (I)]	R1 = 0.0634, wR2 = 0.1443
Final R indexes [all data]	R1 = 0.0860, wR2 = 0.1514
Largest diff. peak/hole / e Å⁻³	0.99/−0.56

[(Ar’GeCH2(Ph)CHGeAr’)Fe]
Identifier	4a
Method	Single-crystal X-ray diffraction
Crystal refinement	Two independent molecules with similar conformations, bond distances and angles are in one asymmetric unit
Empirical formula	C₆₈H₈₂FeGe₂
Formula weight	1100.36
Temperature/K	123.00(10)
Crystal system	monoclinic
Space group	P21
a/Å	12.43830(10)
b/Å	19.30080(10)
c/Å	24.21560(10)
α/°	90
β/°	99.8760(10)
γ/°	90
Volume/Å³	5727.27(6)
Z	4
ρcalc g/cm³	1.276
μ/mm⁻¹	3.53
F(000)	2320
Crystal size/mm³	0.17 × 0.16 × 0.07
Radiation	Cu Kα (λ = 1.54184)
2Θ range for data collection/°	5.89 to 150.428
Index ranges	-15 ≤ h ≤ 13, -24 ≤ k ≤ 24, -30 ≤ l ≤ 30
Reflections collected	157500
Independent reflections	23022 [Rint = 0.0258, Rsigma = 0.0201]
Data/restraints/parameters	23022/1/1311
Goodness-of-fit on F2	1.035
Final R indexes [I>=2σ (I)]	R1 = 0.0213, wR2 = 0.0541
Final R indexes [all data]	R1 = 0.0241, wR2 = 0.0551
Largest diff. peak/hole / e Å⁻³	0.43/−0.34

[(Ar’GeCH2(Ph)CHGeAr’)Fe]
Identifier	4b
Method	Single-crystal X-ray diffraction
Crystal refinement	The structure was refined with a twin law of [-1 0 0 0 -1 0 0 0 -1 2] identified by using Olex2, resulting in a BASF twin fraction of 0.453. Three independent molecules with similar conformations, bond distances and angles are in one asymmetric unit. In one molecule, one iPr group was found to be disordered over two positions (occupancy factors: 0.39/0.61). It was refined with SADI (C−C) restraints. In another molecule, one Dipp group was found to be disordered over two positions (occupancy factors: 0.58/0.42). It was refined with SADI (C−C), SIMU, RIGU and ISOR restraints
Empirical formula	C₆₈H₈₂FeGe₂
Formula weight	1100.36
Temperature/K	123.00(10)
Crystal system	monoclinic
Space group	Cc
a/Å	57.3332(3)
b/Å	13.08435(6)
c/Å	23.35776(10)
α/°	90
β/°	94.1503(4)
γ/°	90
Volume/Å³	17476.30(14)
Z	12
ρcalc g/cm³	1.255
μ/mm⁻¹	3.471
F(000)	6960
Crystal size/mm³	0.123 × 0.104 × 0.046
Radiation	Cu Kα (λ = 1.54184)
2Θ range for data collection/°	6.182 to 151.558
Index ranges	-71 ≤ h ≤ 70, -15 ≤ k ≤ 16, -24 ≤ l ≤ 29
Reflections collected	183253
Independent reflections	32225 [Rint = 0.0282, Rsigma = 0.0258]
Data/restraints/parameters	32225/219/2110
Goodness-of-fit on F2	1.028
Final R indexes [I>=2σ (I)]	R1 = 0.0317, wR2 = 0.0799
Final R indexes [all data]	R1 = 0.0351, wR2 = 0.0831
Largest diff. peak/hole / e Å⁻³	0.55/−0.37

[(Ar’GeCH2(CH3)CC(CH3)CH2GeAr’)Fe]
Identifier	5
Method	Single-crystal X-ray diffraction
Empirical formula	C₆₆H₈₄FeGe₂
Formula weight	1078.36
Temperature/K	123.00(10)
Crystal system	monoclinic
Space group	Cc
a/Å	18.5683(2)
b/Å	17.5342(2)
c/Å	18.1352(2)
α/°	90
β/°	106.0490(10)
γ/°	90
Volume/Å³	5674.34(11)
Z	4
ρcalc g/cm³	1.262
μ/mm⁻¹	3.551
F(000)	2280
Crystal size/mm³	0.104 × 0.076 × 0.038
Radiation	Cu Kα (λ = 1.54184)
2Θ range for data collection/°	7.068 to 150.478
Index ranges	-23 ≤ h ≤ 22, -21 ≤ k ≤ 21, -20 ≤ l ≤ 22
Reflections collected	69674
Independent reflections	10167 [Rint = 0.0272, Rsigma = 0.0203]
Data/restraints/parameters	10167/2/640
Goodness-of-fit on F2	1.02
Final R indexes [I>=2σ (I)]	R1 = 0.0220, wR2 = 0.0561
Final R indexes [all data]	R1 = 0.0234, wR2 = 0.0568
Largest diff. peak/hole / e Å⁻³	0.54/−0.30

[(Ar’(CH2(CH3)CC(CH3)CH2)GeFe(GeAr’)]
Identifier	6
Method	Single-crystal X-ray diffraction
Crystal refinement	One iPr group was found to be disordered over two positions (occupancy factors: 0.68/0.32). one n-pentane molecules per asymmetric unit are severely disordered. They were refined by using a solvent mask which was calculated by Olex2, and 166 electrons were found in a volume of 808 Å³ in one void per unit cell. This is consistent with the presence of 4 n-pentane molecules which account for 168 electrons per unit cell. Although these solvent atoms were not included in the refinement model they are included in the formula and in the calculation of the formula weight, density, μ, F(000), etc. As 6 was crystallized from n-pentane this serves as evidence for the presence of n-pentane in these positions, though they proved to be severely disordered
Empirical formula	C₆₆H₈₄FeGe₂‧C₅H₁₂
Formula weight	1150.5
Temperature/K	123.00(10)
Crystal system	monoclinic
Space group	P21/n
a/Å	11.18347(4)
b/Å	28.28000(9)
c/Å	20.03699(7)
α/°	90
β/°	96.6501(3)
γ/°	90
Volume/Å³	6294.43(4)
Z	4
ρcalc g/cm³	1.214
μ/mm⁻¹	3.23
F(000)	2448
Crystal size/mm³	0.166 × 0.116 × 0.061
Radiation	Cu Kα (λ = 1.54184)
2Θ range for data collection/°	5.43 to 150.522
Index ranges	-13 ≤ h ≤ 13, -35 ≤ k ≤ 35, -24 ≤ l ≤ 24
Reflections collected	162449
Independent reflections	12841 [Rint = 0.0226, Rsigma = 0.0099]
Data/restraints/parameters	12841/0/661
Goodness-of-fit on F2	1.028
Final R indexes [I>=2σ (I)]	R1 = 0.0229, wR2 = 0.0609
Final R indexes [all data]	R1 = 0.0238, wR2 = 0.0613
Largest diff. peak/hole / e Å⁻³	0.85/−0.54

[(Ar’(CH2(CH3)CC(CH3)CH2)SnFe(SnAr’)]
Identifier	7
Method	Single-crystal X-ray diffraction
Crystal refinement	One n-pentane was found disordered around a special position and was refined at half-occupancy. It was refined with SADI, DANG (C−C 2.54 Å), DFIX (C−C 1.52 Å), SIMU and RIGU restraints
Empirical formula	C₆₆H₈₄FeSn₂‧0.5C₅H₁₂
Formula weight	1206.63
Temperature/K	123.00(10)
Crystal system	triclinic
Space group	P-1
a/Å	12.3021(3)
b/Å	14.0812(2)
c/Å	19.1595(3)
α/°	76.9690(10)
β/°	83.9530(10)
γ/°	74.000(2)
Volume/Å³	3104.93(11)
Z	2
ρcalc g/cm³	1.291
μ/mm⁻¹	8.465
F(000)	1254
Crystal size/mm³	0.239 × 0.163 × 0.104
Radiation	Cu Kα (λ = 1.54184)
2Θ range for data collection/°	4.74 to 150.634
Index ranges	-15 ≤ h ≤ 15, -17 ≤ k ≤ 17, -23 ≤ l ≤ 24
Reflections collected	63492
Independent reflections	12613 [Rint = 0.0266, Rsigma = 0.0162]
Data/restraints/parameters	12613/61/687
Goodness-of-fit on F2	1.055
Final R indexes [I>=2σ (I)]	R1 = 0.0218, wR2 = 0.0577
Final R indexes [all data]	R1 = 0.0224, wR2 = 0.0580
Largest diff. peak/hole / e Å⁻³	0.62/−0.65

[Fe(GeAr’)2]
Identifier	1
Selected X-ray bond lengths [Å] and angles [°]	Fe1−Ge1 2.1061(9), Fe1−Ge2 2.4194(9), Ge1−C1 1.928(2), Ge2−C1’ 2.084(2), Ge1···Ge2 2.8738(9), Ge1−Fe1−Ge2 78.51(3), Fe1−Ge1−C1 176.86(7), Fe1−Ge2−C1’ 95.77(6)

[(tBuNC)Fe(GeAr’)2]
Identifier	2
Selected X-ray bond lengths [Å] and angles [°]	Fe1−Ge1 2.2916(5), Fe1−Ge2 2.9513(6), Fe1−C3 1.831(3), Ge1−C1 1.993(3), Ge2−C2 2.018(3), Ge1−Ge2 2.3787(5), Ge1−Fe1−Ge2 52.14(1), Fe1−Ge1−C1 121.39(8), Fe1−Ge2−C2 91.03(8), C1−Ge1−Ge2 68.82(1), C2−Ge2−Ge1 113.66(8)

[(tBuNC)Fe(GeAr’)2]
Identifier	2
Experimental X-ray bond lengths [Å] and angles [°]	Fe1–Ge1/Ge2 2.2916(5)/ 2.9513(6), Ge1/Ge2–Cipso 1.993(3)/ 2.018(3), Ge1–Ge2 2.3787(5), Fe1–C3 1.831(3), Fe1–Ge1/Ge2–Cipso 121.39(8)/ 91.03(8), C1−Ge1−Ge2 119.09(8), C2−Ge2−Ge1 113.66(8)

[(Ar’GeH2)Fe(GeAr’)]
Identifier	3
Selected X-ray bond lengths [Å] and angles [°]	Fe1−Ge1 2.0994(6), Fe1−Ge2 2.3968(7), Ge1−C1 1.930(2), Ge2−C1’ 2.006(2), Ge1···Ge2 3.0161(6), Ge1−Fe1−Ge2 83.98(2), Fe1−Ge1−C1 176.03(6), Fe1−Ge2−C1’ 101.32(5)

[(Ar’GeH2)Fe(GeAr’)]
Identifier	3
Experimental X-ray bond lengths [Å] and angles [°]	Fe1–Ge1/Ge2 2.091(2)/ 2.408(2), Ge1/Ge2–Cipso 1.928(4)/ 2.003(2), Ge1···Ge2 3.013(2), Ge2–H 1.59(2)/1.59(2), Fe1–Ge1/Ge2–Cipso 176.18(14)/ 100.70(12)

[(Ar’GeCH2(Ph)CHGeAr’)Fe]
Identifier	4a
Selected X-ray bond lengths [Å] and angles [°]	Fe1−Ge1 2.2441(4), Fe1−Ge2 2.1857(4), Ge1−C1 2.020(2), Ge1−C4 2.074(2), Ge2−C2 1.955(2), Ge2−C3 1.970(2), C3−C4 1.534(3), Ge1···Ge2 2.8442(3), Ge1−Fe1−Ge2 79.88(1), C1−Ge1−C4 102.54(8), C2−Ge2−C3 128.02(9)

[(Ar’GeCH2(Ph)CHGeAr’)Fe]
Identifier	4b
Selected X-ray bond lengths [Å] and angles [°]	Fe1−Ge1 2.2171(8), Fe1−Ge2 2.1833(7), Ge1−C1 2.001(4), Ge1−C3 2.026(4), Ge2−C2 1.976(4), Ge2−C4 2.000(4), C3−C4 1.533(5), Ge1···Ge2 2.8497(6), Ge1−Fe1−Ge2 80.72(3), C1−Ge1−C3 100.42(16), C2−Ge2−C4 129.25(16)

[(Ar’GeCH2(CH3)CC(CH3)CH2GeAr’)Fe]
Identifier	5
Selected X-ray bond lengths [Å] and angles [°]	Fe1−Ge1 2.2260(5), Fe1−Ge2 2.2150(5), Ge1−C1 2.030(3), Ge1−C6 2.012(3), Ge2−C2 1.990(3), Ge2−C3 1.987(3), C4−C5 1.344(4), Ge1···Ge2 3.0663(6), Ge1−Fe1−Ge2 87.33(2), C1−Ge1−C6 96.05(11), C2−Ge2−C3 116.60(12)

[(Ar’(CH2(CH3)CC(CH3)CH2)GeFe(GeAr’)]
Identifier	6
Selected X-ray bond lengths [Å] and angles [°]	Fe1−Ge1 2.1069(2), Fe1−Ge2 2.4021(2), Ge1−C1 1.956(1), Ge2−C2 2.010(1), Ge2−C3 1.982(1), Ge2−C6 1.993(1), C4−C5 1.337(2), Ge1···Ge2 3.2368(8), Fe1−Ge1−C1 168.39(4), Ge1−Fe1−Ge2 91.514(8), Fe1−Ge2−C2 101.03(3) C3−Ge2−C6 90.70(5)

[(Ar’(CH2(CH3)CC(CH3)CH2)SnFe(SnAr’)]
Identifier	7
Selected X-ray bond lengths [Å] and angles [°]	Fe1−Sn1 2.2904(3), Fe1−Sn2 2.5778(3), Sn1−C1 2.1428(16), Sn2−C2 2.2016(15), Sn2−C3 2.1849(17), Sn2−C6 2.1648(16), C4−C5 1.342(2), Sn1···Sn2 3.4730(4), Fe1−Sn1−C1 170.97(4), Sn1−Fe1−Sn2 90.829(9), Fe1−Sn2−C2 95.72(4) C3−Sn2−C6 84.72(6)