metal-organic compounds
Di-μ-oxido-bis[bis(diisopropylacetamidinato)-κN;κ2N,N′-germanium(IV)]
aChemisches Institut, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, D-39106 Magdeburg, Germany, bInstitut für Mikro- und Sensorsysteme, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, D-39106 Magdeburg, Germany, and cInstitut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany
*Correspondence e-mail: frank.edelmann@ovgu.de
The title compound, [Ge2(C8H17N2)4O2], crystallizes with imposed twofold symmetry, which allows the monodentate amidinate ligands to be arranged in a cisoid fashion. The independent Ge—O distances within the central Ge2O2 ring, which is essentially planar (r.m.s. deviation = 0.039 Å), are 1.7797 (8) and 1.8568 (8) Å. The germanium centres adopt a distorted trigonal–bipyramidal geometry, being coordinated by the two O atoms and by one bidentate and one monodentate amidinate ligand (three N atoms). One N-isopropyl group is disordered over two positions; these are mutually exclusive because of `collisions' between symmetry-equivalent methyl groups and thus each has 0.5 occupancy.
CCDC reference: 973636
Related literature
For comprehensive reviews on metal amidinates and guanidinates, see: Edelmann (2008, 2013). For information on germanium precursors for CVD or ALD production of GST thin layers, see: Chen et al. (2007, 2009, 2010); Lee et al. (2007). For previous literature on related germanium amidinates, see: Brück et al. (2012); Cabeza et al. (2013); Foley et al. (1997, 2000); Jones et al. (2008); Jutzi et al. (1999); Karsch et al. (1998); Kühl (2004); Matioszek et al. (2012); Yeong et al. (2012); Zhang & So (2011).
Experimental
Crystal data
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Data collection: CrysAlis PRO (Agilent, 2012); cell CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP (Siemens, 1994); software used to prepare material for publication: publCIF (Westrip, 2010).
Supporting information
CCDC reference: 973636
10.1107/S1600536813032133/zl2570sup1.cif
contains datablocks I, New_Global_Publ_Block. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536813032133/zl2570Isup2.hkl
The bis(chelated) germylene derivative [MeC(NiPr)2]2Ge was prepared according to the published procedure by treatment of GeCl2(dioxane) with two equivalents of (THF)Li[MeC(NiPr)2] (Karsch et al., 1998). Subsequent recrystallization from n-pentane afforded a small amount of well formed, colorless, plate-like single crystals, which were shown by X-ray diffraction to be the title compound. Its formation can only be explained by oxygen contamination during the recrystallization process.
Ordered methyls were refined as idealized rigid groups (C—H 0.98 Å, H—C—H 109.5°) allowed to rotate but not tip; starting positions for the hydrogen sites were taken from a difference synthesis. The methyl group at C2 is rotationally disordered and was refined as above, but with an idealized hexagon of partially occupied alternative hydrogen sites. Other hydrogen atoms were placed in calculated positions and refined using a riding model with C—Hmethine 1.00 Å; the hydrogen U values were fixed at 1.5 × U(eq) of the parent atom for methyl H and 1.2 × U(eq) of the parent atom for other H.
The N-isopropyl group N4, C14–16 is disordered over two positions. These are mutually exclusive because of "collisions" between symmetry-equivalent C16 methyl groups and thus each have occupancies of 0.5. Appropriate similarity restraints were employed to improve stability of
Methyl groups of disordered atoms (C15, C16) were refined using a riding model starting from ideally staggered positions.Data collection: CrysAlis PRO (Agilent, 2012); cell
CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis PRO (Agilent, 2012); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP (Siemens, 1994); software used to prepare material for publication: publCIF (Westrip, 2010).Fig. 1. The molecular structure of the title compound in the crystal. Thermal ellipsoids represent 50% probability levels. Only one component of the disordered group N4, C14–16 is shown. |
[Ge2(C8H17N2)4O2] | F(000) = 1584 |
Mr = 742.12 | Dx = 1.224 Mg m−3 |
Monoclinic, C2/c | Cu Kα radiation, λ = 1.54184 Å |
a = 20.1934 (2) Å | Cell parameters from 28247 reflections |
b = 12.7424 (1) Å | θ = 4.1–75.7° |
c = 15.9008 (1) Å | µ = 2.11 mm−1 |
β = 100.038 (1)° | T = 100 K |
V = 4028.84 (6) Å3 | Plate, colourless |
Z = 4 | 0.08 × 0.08 × 0.04 mm |
Oxford Diffraction Xcalibur (Atlas, Nova) diffractometer | 4173 independent reflections |
Radiation source: Nova (Cu) X-ray Source | 4014 reflections with I > 2σ(I) |
Mirror monochromator | Rint = 0.021 |
Detector resolution: 10.3543 pixels mm-1 | θmax = 75.9°, θmin = 4.1° |
ω scan | h = −24→25 |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012) | k = −16→15 |
Tmin = 0.837, Tmax = 1.000 | l = −19→19 |
35712 measured reflections |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.020 | H-atom parameters constrained |
wR(F2) = 0.057 | w = 1/[σ2(Fo2) + (0.0296P)2 + 2.8972P] where P = (Fo2 + 2Fc2)/3 |
S = 1.08 | (Δ/σ)max = 0.002 |
4173 reflections | Δρmax = 0.27 e Å−3 |
245 parameters | Δρmin = −0.29 e Å−3 |
28 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.000087 (13) |
[Ge2(C8H17N2)4O2] | V = 4028.84 (6) Å3 |
Mr = 742.12 | Z = 4 |
Monoclinic, C2/c | Cu Kα radiation |
a = 20.1934 (2) Å | µ = 2.11 mm−1 |
b = 12.7424 (1) Å | T = 100 K |
c = 15.9008 (1) Å | 0.08 × 0.08 × 0.04 mm |
β = 100.038 (1)° |
Oxford Diffraction Xcalibur (Atlas, Nova) diffractometer | 4173 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012) | 4014 reflections with I > 2σ(I) |
Tmin = 0.837, Tmax = 1.000 | Rint = 0.021 |
35712 measured reflections |
R[F2 > 2σ(F2)] = 0.020 | 28 restraints |
wR(F2) = 0.057 | H-atom parameters constrained |
S = 1.08 | Δρmax = 0.27 e Å−3 |
4173 reflections | Δρmin = −0.29 e Å−3 |
245 parameters |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Ge1 | 0.439398 (6) | 0.244195 (9) | 0.200846 (8) | 0.01509 (6) | |
O1 | 0.52408 (4) | 0.25038 (5) | 0.18371 (5) | 0.01763 (17) | |
N1 | 0.37824 (5) | 0.35942 (7) | 0.19850 (6) | 0.01908 (19) | |
N2 | 0.39972 (5) | 0.30266 (8) | 0.07745 (6) | 0.01980 (19) | |
N3 | 0.39391 (5) | 0.11656 (7) | 0.19497 (6) | 0.01919 (19) | |
C1 | 0.36719 (5) | 0.37371 (9) | 0.11299 (7) | 0.0202 (2) | |
C2 | 0.32297 (7) | 0.45872 (10) | 0.06893 (8) | 0.0308 (3) | |
H2A | 0.3174 | 0.4490 | 0.0070 | 0.046* | 0.680 (18) |
H2B | 0.3437 | 0.5272 | 0.0843 | 0.046* | 0.680 (18) |
H2C | 0.2789 | 0.4556 | 0.0867 | 0.046* | 0.680 (18) |
H2D | 0.3093 | 0.5055 | 0.1117 | 0.046* | 0.320 (18) |
H2E | 0.2830 | 0.4273 | 0.0343 | 0.046* | 0.320 (18) |
H2F | 0.3477 | 0.4989 | 0.0320 | 0.046* | 0.320 (18) |
C3 | 0.36233 (6) | 0.43549 (9) | 0.26152 (7) | 0.0231 (2) | |
H3 | 0.3236 | 0.4791 | 0.2331 | 0.028* | |
C4 | 0.42119 (7) | 0.50889 (11) | 0.29111 (9) | 0.0340 (3) | |
H4A | 0.4595 | 0.4684 | 0.3208 | 0.051* | |
H4B | 0.4081 | 0.5615 | 0.3301 | 0.051* | |
H4C | 0.4339 | 0.5441 | 0.2415 | 0.051* | |
C5 | 0.34071 (7) | 0.37987 (11) | 0.33699 (8) | 0.0321 (3) | |
H5A | 0.3003 | 0.3380 | 0.3169 | 0.048* | |
H5B | 0.3309 | 0.4320 | 0.3784 | 0.048* | |
H5C | 0.3770 | 0.3337 | 0.3643 | 0.048* | |
C6 | 0.39731 (7) | 0.28663 (11) | −0.01370 (8) | 0.0301 (3) | |
H6 | 0.3740 | 0.3482 | −0.0448 | 0.036* | |
C7 | 0.46850 (10) | 0.28230 (19) | −0.03182 (10) | 0.0619 (6) | |
H7A | 0.4911 | 0.3492 | −0.0157 | 0.093* | |
H7B | 0.4673 | 0.2695 | −0.0928 | 0.093* | |
H7C | 0.4931 | 0.2254 | 0.0014 | 0.093* | |
C8 | 0.35668 (12) | 0.18830 (13) | −0.04264 (10) | 0.0604 (6) | |
H8A | 0.3792 | 0.1269 | −0.0135 | 0.091* | |
H8B | 0.3532 | 0.1799 | −0.1045 | 0.091* | |
H8C | 0.3115 | 0.1949 | −0.0285 | 0.091* | |
C9 | 0.40646 (6) | 0.02753 (9) | 0.15071 (7) | 0.0216 (2) | |
C10 | 0.47448 (6) | 0.02267 (9) | 0.12292 (8) | 0.0266 (3) | |
H10A | 0.5042 | −0.0244 | 0.1610 | 0.040* | |
H10B | 0.4942 | 0.0931 | 0.1255 | 0.040* | |
H10C | 0.4690 | −0.0039 | 0.0643 | 0.040* | |
C11 | 0.33400 (6) | 0.12089 (9) | 0.23715 (8) | 0.0236 (2) | |
H11 | 0.3388 | 0.1868 | 0.2718 | 0.028* | |
C12 | 0.33045 (7) | 0.03191 (13) | 0.30052 (9) | 0.0370 (3) | |
H12A | 0.3182 | −0.0335 | 0.2692 | 0.055* | |
H12B | 0.2965 | 0.0485 | 0.3356 | 0.055* | |
H12C | 0.3744 | 0.0236 | 0.3374 | 0.055* | |
C13 | 0.26852 (6) | 0.13273 (11) | 0.17384 (9) | 0.0320 (3) | |
H13A | 0.2720 | 0.1928 | 0.1364 | 0.048* | |
H13B | 0.2314 | 0.1442 | 0.2050 | 0.048* | |
H13C | 0.2601 | 0.0688 | 0.1394 | 0.048* | |
N4 | 0.3607 (6) | −0.0436 (7) | 0.1284 (5) | 0.0219 (13) | 0.50 |
C14 | 0.3734 (4) | −0.1437 (6) | 0.0885 (4) | 0.0274 (15) | 0.50 |
H14 | 0.4104 | −0.1343 | 0.0548 | 0.033* | 0.50 |
C15 | 0.3947 (3) | −0.2241 (3) | 0.1584 (3) | 0.0514 (9) | 0.50 |
H15A | 0.4348 | −0.1987 | 0.1969 | 0.077* | 0.50 |
H15B | 0.4051 | −0.2907 | 0.1327 | 0.077* | 0.50 |
H15C | 0.3581 | −0.2347 | 0.1906 | 0.077* | 0.50 |
C16 | 0.30970 (18) | −0.1764 (3) | 0.0291 (2) | 0.0430 (8) | 0.50 |
H16A | 0.2969 | −0.1219 | −0.0142 | 0.064* | 0.50 |
H16B | 0.2734 | −0.1860 | 0.0620 | 0.064* | 0.50 |
H16C | 0.3176 | −0.2426 | 0.0009 | 0.064* | 0.50 |
N4' | 0.3645 (7) | −0.0479 (7) | 0.1505 (5) | 0.0255 (15) | 0.50 |
C14' | 0.3827 (5) | −0.1470 (7) | 0.1139 (5) | 0.0335 (16) | 0.50 |
H14' | 0.4326 | −0.1515 | 0.1188 | 0.040* | 0.50 |
C15' | 0.3495 (3) | −0.1540 (3) | 0.0203 (3) | 0.0619 (11) | 0.50 |
H15D | 0.3689 | −0.1008 | −0.0126 | 0.093* | 0.50 |
H15E | 0.3011 | −0.1419 | 0.0153 | 0.093* | 0.50 |
H15F | 0.3573 | −0.2239 | −0.0018 | 0.093* | 0.50 |
C16' | 0.3578 (3) | −0.2357 (3) | 0.1644 (3) | 0.0570 (12) | 0.50 |
H16D | 0.3818 | −0.2337 | 0.2236 | 0.086* | 0.50 |
H16E | 0.3660 | −0.3032 | 0.1386 | 0.086* | 0.50 |
H16F | 0.3094 | −0.2273 | 0.1638 | 0.086* | 0.50 |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ge1 | 0.01334 (8) | 0.01533 (8) | 0.01667 (8) | 0.00042 (4) | 0.00282 (5) | −0.00043 (4) |
O1 | 0.0150 (4) | 0.0206 (4) | 0.0175 (4) | −0.0007 (3) | 0.0031 (3) | 0.0003 (3) |
N1 | 0.0190 (4) | 0.0190 (4) | 0.0191 (4) | 0.0041 (4) | 0.0028 (3) | −0.0008 (4) |
N2 | 0.0208 (5) | 0.0214 (5) | 0.0169 (4) | 0.0033 (4) | 0.0023 (3) | 0.0011 (3) |
N3 | 0.0160 (4) | 0.0183 (4) | 0.0241 (5) | −0.0020 (3) | 0.0058 (3) | −0.0019 (4) |
C1 | 0.0183 (5) | 0.0196 (5) | 0.0220 (5) | 0.0004 (4) | 0.0020 (4) | 0.0006 (4) |
C2 | 0.0372 (7) | 0.0278 (6) | 0.0257 (6) | 0.0132 (5) | 0.0012 (5) | 0.0028 (5) |
C3 | 0.0237 (6) | 0.0218 (5) | 0.0242 (6) | 0.0063 (4) | 0.0058 (4) | −0.0031 (4) |
C4 | 0.0377 (7) | 0.0273 (6) | 0.0374 (7) | −0.0013 (5) | 0.0074 (6) | −0.0128 (5) |
C5 | 0.0388 (7) | 0.0322 (7) | 0.0292 (6) | 0.0091 (6) | 0.0164 (5) | −0.0014 (5) |
C6 | 0.0408 (7) | 0.0322 (7) | 0.0171 (6) | 0.0140 (6) | 0.0041 (5) | 0.0013 (5) |
C7 | 0.0561 (11) | 0.1062 (15) | 0.0287 (8) | 0.0446 (11) | 0.0226 (7) | 0.0206 (9) |
C8 | 0.1093 (16) | 0.0335 (8) | 0.0285 (7) | 0.0050 (9) | −0.0156 (9) | −0.0068 (6) |
C9 | 0.0202 (5) | 0.0178 (5) | 0.0275 (6) | 0.0012 (4) | 0.0060 (4) | 0.0006 (4) |
C10 | 0.0236 (6) | 0.0221 (6) | 0.0362 (7) | −0.0009 (5) | 0.0115 (5) | −0.0049 (5) |
C11 | 0.0190 (5) | 0.0241 (6) | 0.0295 (6) | −0.0041 (4) | 0.0092 (4) | −0.0043 (5) |
C12 | 0.0257 (6) | 0.0545 (9) | 0.0320 (7) | −0.0064 (6) | 0.0087 (5) | 0.0118 (6) |
C13 | 0.0184 (6) | 0.0322 (7) | 0.0458 (8) | 0.0016 (5) | 0.0067 (5) | 0.0079 (6) |
N4 | 0.0254 (19) | 0.0206 (16) | 0.023 (3) | −0.0030 (12) | 0.012 (3) | −0.005 (2) |
C14 | 0.032 (3) | 0.0166 (16) | 0.037 (4) | −0.0058 (15) | 0.015 (3) | −0.012 (2) |
C15 | 0.066 (3) | 0.0216 (16) | 0.069 (3) | 0.0049 (18) | 0.021 (2) | −0.0015 (16) |
C16 | 0.0405 (18) | 0.0405 (18) | 0.0509 (18) | −0.0121 (14) | 0.0162 (15) | −0.0264 (14) |
N4' | 0.034 (2) | 0.0169 (16) | 0.029 (4) | −0.0040 (12) | 0.014 (3) | −0.006 (2) |
C14' | 0.035 (3) | 0.028 (2) | 0.040 (4) | −0.0088 (17) | 0.013 (3) | −0.016 (2) |
C15' | 0.072 (3) | 0.045 (2) | 0.064 (3) | −0.003 (2) | 0.002 (2) | −0.0315 (19) |
C16' | 0.074 (3) | 0.0186 (15) | 0.088 (3) | −0.0006 (18) | 0.041 (3) | −0.0027 (15) |
Ge1—O1 | 1.7797 (8) | C8—H8C | 0.9800 |
Ge1—O1i | 1.8568 (8) | C9—N4' | 1.281 (12) |
Ge1—N3 | 1.8621 (9) | C9—N4 | 1.299 (12) |
Ge1—N1 | 1.9148 (9) | C9—C10 | 1.5157 (15) |
Ge1—N2 | 2.1211 (9) | C10—H10A | 0.9800 |
O1—Ge1i | 1.8568 (8) | C10—H10B | 0.9800 |
N1—C1 | 1.3512 (14) | C10—H10C | 0.9800 |
N1—C3 | 1.4694 (14) | C11—C13 | 1.5234 (17) |
N2—C1 | 1.3038 (15) | C11—C12 | 1.5268 (18) |
N2—C6 | 1.4560 (14) | C11—H11 | 1.0000 |
N3—C9 | 1.3816 (14) | C12—H12A | 0.9800 |
N3—C11 | 1.4831 (14) | C12—H12B | 0.9800 |
C1—C2 | 1.4978 (16) | C12—H12C | 0.9800 |
C2—H2A | 0.9800 | C13—H13A | 0.9800 |
C2—H2B | 0.9800 | C13—H13B | 0.9800 |
C2—H2C | 0.9800 | C13—H13C | 0.9800 |
C2—H2D | 0.9800 | N4—C14 | 1.467 (9) |
C2—H2E | 0.9800 | C14—C16 | 1.516 (7) |
C2—H2F | 0.9800 | C14—C15 | 1.517 (7) |
C3—C4 | 1.5211 (17) | C14—H14 | 1.0000 |
C3—C5 | 1.5218 (17) | C15—H15A | 0.9800 |
C3—H3 | 1.0000 | C15—H15B | 0.9800 |
C4—H4A | 0.9800 | C15—H15C | 0.9800 |
C4—H4B | 0.9800 | C16—H16A | 0.9800 |
C4—H4C | 0.9800 | C16—H16B | 0.9800 |
C5—H5A | 0.9800 | C16—H16C | 0.9800 |
C5—H5B | 0.9800 | N4'—C14' | 1.463 (9) |
C5—H5C | 0.9800 | C14'—C16' | 1.522 (9) |
C6—C7 | 1.516 (2) | C14'—C15' | 1.524 (7) |
C6—C8 | 1.524 (2) | C14'—H14' | 1.0000 |
C6—H6 | 1.0000 | C15'—H15D | 0.9800 |
C7—H7A | 0.9800 | C15'—H15E | 0.9800 |
C7—H7B | 0.9800 | C15'—H15F | 0.9800 |
C7—H7C | 0.9800 | C16'—H16D | 0.9800 |
C8—H8A | 0.9800 | C16'—H16E | 0.9800 |
C8—H8B | 0.9800 | C16'—H16F | 0.9800 |
O1—Ge1—O1i | 85.57 (4) | H7A—C7—H7C | 109.5 |
O1—Ge1—N3 | 120.65 (4) | H7B—C7—H7C | 109.5 |
O1i—Ge1—N3 | 101.19 (4) | C6—C8—H8A | 109.5 |
O1—Ge1—N1 | 126.64 (4) | C6—C8—H8B | 109.5 |
O1i—Ge1—N1 | 97.49 (4) | H8A—C8—H8B | 109.5 |
N3—Ge1—N1 | 110.97 (4) | C6—C8—H8C | 109.5 |
O1—Ge1—N2 | 93.50 (4) | H8A—C8—H8C | 109.5 |
O1i—Ge1—N2 | 157.00 (3) | H8B—C8—H8C | 109.5 |
N3—Ge1—N2 | 99.02 (4) | N4'—C9—N3 | 116.0 (5) |
N1—Ge1—N2 | 64.80 (4) | N4—C9—N3 | 121.8 (5) |
Ge1—O1—Ge1i | 94.21 (4) | N4'—C9—C10 | 126.9 (5) |
C1—N1—C3 | 125.44 (9) | N4—C9—C10 | 122.0 (5) |
C1—N1—Ge1 | 96.65 (7) | N3—C9—C10 | 115.98 (10) |
C3—N1—Ge1 | 135.19 (7) | C9—C10—H10A | 109.5 |
C1—N2—C6 | 126.65 (10) | C9—C10—H10B | 109.5 |
C1—N2—Ge1 | 88.89 (7) | H10A—C10—H10B | 109.5 |
C6—N2—Ge1 | 144.41 (8) | C9—C10—H10C | 109.5 |
C9—N3—C11 | 119.83 (9) | H10A—C10—H10C | 109.5 |
C9—N3—Ge1 | 127.60 (8) | H10B—C10—H10C | 109.5 |
C11—N3—Ge1 | 112.27 (7) | N3—C11—C13 | 112.79 (10) |
N2—C1—N1 | 109.59 (10) | N3—C11—C12 | 114.00 (10) |
N2—C1—C2 | 127.14 (11) | C13—C11—C12 | 112.00 (10) |
N1—C1—C2 | 123.27 (10) | N3—C11—H11 | 105.7 |
N2—C1—Ge1 | 59.23 (6) | C13—C11—H11 | 105.7 |
N1—C1—Ge1 | 50.41 (5) | C12—C11—H11 | 105.7 |
C2—C1—Ge1 | 173.51 (9) | C11—C12—H12A | 109.5 |
C1—C2—H2A | 109.5 | C11—C12—H12B | 109.5 |
C1—C2—H2B | 109.5 | H12A—C12—H12B | 109.5 |
H2A—C2—H2B | 109.5 | C11—C12—H12C | 109.5 |
C1—C2—H2C | 109.5 | H12A—C12—H12C | 109.5 |
H2A—C2—H2C | 109.5 | H12B—C12—H12C | 109.5 |
H2B—C2—H2C | 109.5 | C11—C13—H13A | 109.5 |
C1—C2—H2D | 109.5 | C11—C13—H13B | 109.5 |
H2A—C2—H2D | 141.1 | H13A—C13—H13B | 109.5 |
H2B—C2—H2D | 56.3 | C11—C13—H13C | 109.5 |
H2C—C2—H2D | 56.3 | H13A—C13—H13C | 109.5 |
C1—C2—H2E | 109.5 | H13B—C13—H13C | 109.5 |
H2A—C2—H2E | 56.3 | C9—N4—C14 | 123.7 (9) |
H2B—C2—H2E | 141.1 | N4—C14—C16 | 108.3 (7) |
H2C—C2—H2E | 56.3 | N4—C14—C15 | 108.6 (6) |
H2D—C2—H2E | 109.5 | C16—C14—C15 | 111.9 (6) |
C1—C2—H2F | 109.5 | N4—C14—H14 | 109.3 |
H2A—C2—H2F | 56.3 | C16—C14—H14 | 109.3 |
H2B—C2—H2F | 56.3 | C15—C14—H14 | 109.3 |
H2C—C2—H2F | 141.1 | C14—C15—H15A | 109.5 |
H2D—C2—H2F | 109.5 | C14—C15—H15B | 109.5 |
H2E—C2—H2F | 109.5 | H15A—C15—H15B | 109.5 |
N1—C3—C4 | 111.39 (10) | C14—C15—H15C | 109.5 |
N1—C3—C5 | 110.94 (10) | H15A—C15—H15C | 109.5 |
C4—C3—C5 | 111.01 (11) | H15B—C15—H15C | 109.5 |
N1—C3—H3 | 107.8 | C14—C16—H16A | 109.5 |
C4—C3—H3 | 107.8 | C14—C16—H16B | 109.5 |
C5—C3—H3 | 107.8 | H16A—C16—H16B | 109.5 |
C3—C4—H4A | 109.5 | C14—C16—H16C | 109.5 |
C3—C4—H4B | 109.5 | H16A—C16—H16C | 109.5 |
H4A—C4—H4B | 109.5 | H16B—C16—H16C | 109.5 |
C3—C4—H4C | 109.5 | C9—N4'—C14' | 115.9 (10) |
H4A—C4—H4C | 109.5 | N4'—C14'—C16' | 107.6 (7) |
H4B—C4—H4C | 109.5 | N4'—C14'—C15' | 109.9 (6) |
C3—C5—H5A | 109.5 | C16'—C14'—C15' | 110.0 (6) |
C3—C5—H5B | 109.5 | N4'—C14'—H14' | 109.8 |
H5A—C5—H5B | 109.5 | C16'—C14'—H14' | 109.8 |
C3—C5—H5C | 109.5 | C15'—C14'—H14' | 109.8 |
H5A—C5—H5C | 109.5 | C14'—C15'—H15D | 109.5 |
H5B—C5—H5C | 109.5 | C14'—C15'—H15E | 109.5 |
N2—C6—C7 | 109.03 (11) | H15D—C15'—H15E | 109.5 |
N2—C6—C8 | 109.80 (12) | C14'—C15'—H15F | 109.5 |
C7—C6—C8 | 113.02 (15) | H15D—C15'—H15F | 109.5 |
N2—C6—H6 | 108.3 | H15E—C15'—H15F | 109.5 |
C7—C6—H6 | 108.3 | C14'—C16'—H16D | 109.5 |
C8—C6—H6 | 108.3 | C14'—C16'—H16E | 109.5 |
C6—C7—H7A | 109.5 | H16D—C16'—H16E | 109.5 |
C6—C7—H7B | 109.5 | C14'—C16'—H16F | 109.5 |
H7A—C7—H7B | 109.5 | H16D—C16'—H16F | 109.5 |
C6—C7—H7C | 109.5 | H16E—C16'—H16F | 109.5 |
O1i—Ge1—O1—Ge1i | 4.88 (4) | C3—N1—C1—Ge1 | 163.67 (13) |
N3—Ge1—O1—Ge1i | −95.52 (4) | O1—Ge1—C1—N2 | 58.62 (7) |
N1—Ge1—O1—Ge1i | 100.93 (4) | O1i—Ge1—C1—N2 | 161.01 (6) |
N2—Ge1—O1—Ge1i | 161.84 (3) | N3—Ge1—C1—N2 | −76.93 (7) |
O1—Ge1—N1—C1 | 72.88 (8) | N1—Ge1—C1—N2 | −177.09 (11) |
O1i—Ge1—N1—C1 | 162.93 (7) | O1—Ge1—C1—N1 | −124.28 (7) |
N3—Ge1—N1—C1 | −92.00 (7) | O1i—Ge1—C1—N1 | −21.89 (9) |
N2—Ge1—N1—C1 | −1.70 (6) | N3—Ge1—C1—N1 | 100.16 (7) |
O1—Ge1—N1—C3 | −88.15 (11) | N2—Ge1—C1—N1 | 177.09 (11) |
O1i—Ge1—N1—C3 | 1.89 (11) | C1—N1—C3—C4 | −89.99 (14) |
N3—Ge1—N1—C3 | 106.97 (11) | Ge1—N1—C3—C4 | 66.67 (14) |
N2—Ge1—N1—C3 | −162.73 (12) | C1—N1—C3—C5 | 145.80 (11) |
O1—Ge1—N2—C1 | −127.45 (7) | Ge1—N1—C3—C5 | −57.54 (14) |
O1i—Ge1—N2—C1 | −40.55 (12) | C1—N2—C6—C7 | 129.19 (15) |
N3—Ge1—N2—C1 | 110.76 (7) | Ge1—N2—C6—C7 | −54.4 (2) |
N1—Ge1—N2—C1 | 1.75 (7) | C1—N2—C6—C8 | −106.49 (15) |
O1—Ge1—N2—C6 | 55.45 (15) | Ge1—N2—C6—C8 | 69.89 (19) |
O1i—Ge1—N2—C6 | 142.36 (14) | C11—N3—C9—N4' | −1.0 (5) |
N3—Ge1—N2—C6 | −66.34 (15) | Ge1—N3—C9—N4' | −174.2 (5) |
N1—Ge1—N2—C6 | −175.35 (16) | C11—N3—C9—N4 | 15.5 (5) |
O1—Ge1—N3—C9 | −24.75 (11) | Ge1—N3—C9—N4 | −157.6 (4) |
O1i—Ge1—N3—C9 | −116.23 (10) | C11—N3—C9—C10 | −169.85 (10) |
N1—Ge1—N3—C9 | 141.17 (9) | Ge1—N3—C9—C10 | 17.01 (15) |
N2—Ge1—N3—C9 | 74.80 (10) | C9—N3—C11—C13 | −73.08 (14) |
O1—Ge1—N3—C11 | 161.68 (7) | Ge1—N3—C11—C13 | 101.05 (10) |
O1i—Ge1—N3—C11 | 70.20 (8) | C9—N3—C11—C12 | 56.10 (15) |
N1—Ge1—N3—C11 | −32.40 (9) | Ge1—N3—C11—C12 | −129.76 (9) |
N2—Ge1—N3—C11 | −98.78 (8) | N4'—C9—N4—C14 | −102 (4) |
C6—N2—C1—N1 | 175.52 (11) | N3—C9—N4—C14 | −174.1 (5) |
Ge1—N2—C1—N1 | −2.38 (9) | C10—C9—N4—C14 | 11.6 (9) |
C6—N2—C1—C2 | −3.6 (2) | C9—N4—C14—C16 | −148.6 (7) |
Ge1—N2—C1—C2 | 178.47 (12) | C9—N4—C14—C15 | 89.7 (9) |
C6—N2—C1—Ge1 | 177.89 (13) | N4—C9—N4'—C14' | 72 (3) |
C3—N1—C1—N2 | 166.32 (10) | N3—C9—N4'—C14' | −171.9 (5) |
Ge1—N1—C1—N2 | 2.65 (10) | C10—C9—N4'—C14' | −4.5 (9) |
C3—N1—C1—C2 | −14.48 (18) | C9—N4'—C14'—C16' | 145.1 (7) |
Ge1—N1—C1—C2 | −178.16 (10) | C9—N4'—C14'—C15' | −95.1 (9) |
Symmetry code: (i) −x+1, y, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | [Ge2(C8H17N2)4O2] |
Mr | 742.12 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 100 |
a, b, c (Å) | 20.1934 (2), 12.7424 (1), 15.9008 (1) |
β (°) | 100.038 (1) |
V (Å3) | 4028.84 (6) |
Z | 4 |
Radiation type | Cu Kα |
µ (mm−1) | 2.11 |
Crystal size (mm) | 0.08 × 0.08 × 0.04 |
Data collection | |
Diffractometer | Oxford Diffraction Xcalibur (Atlas, Nova) diffractometer |
Absorption correction | Multi-scan (CrysAlis PRO; Agilent, 2012) |
Tmin, Tmax | 0.837, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 35712, 4173, 4014 |
Rint | 0.021 |
(sin θ/λ)max (Å−1) | 0.629 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.020, 0.057, 1.08 |
No. of reflections | 4173 |
No. of parameters | 245 |
No. of restraints | 28 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.27, −0.29 |
Computer programs: CrysAlis PRO (Agilent, 2012), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), XP (Siemens, 1994), publCIF (Westrip, 2010).
Acknowledgements
Financial support of this work by the Deutsche Forschungsgemeinschaft (DFG), grants Nos. ED 29/22–1 and BU 978/50–1, is gratefully acknowledged.
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Amidinate and guanidinate anions have been widely employed as versatile chelating ligands that form complexes with virtually every metallic element across the Periodic Table (Edelmann 2008, 2013). Among these, germanium compounds comprising amidinate or guanidinate ligands are currently under active investigation as precursors for the deposition of Ge—Sb—Te (= GST) chalcogenide alloys via CVD and ALD processes to be used in next generation non-volatile Phase Change Random Access Memory (PRAM) devices (Chen et al., 2007, 2009, 2010; Lee et al., 2007). The first fully characterized amidinate complexes of germanium were [MeC(NCy)2]2Ge and [tBuC(NCy)2]2Ge, which were both prepared by metathetical reactions between GeCl2(dioxane) and the respective lithium amidinates, Li[MeC(NCy)2] and Li[tBuC(NCy)2]. The coordination geometry around germanium was found to be distorted tetrahedral, with one of the vertices being occupied by a lone pair of electrons. Both molecules exhibit one chelating and one monodentate ("dangling") amidinate ligand. Mixed amidinato-amido analogues such as [MeC(NCy)2]GeN(SiMe3)2 (R = Me, tBu) were prepared in a similar manner (Kühl, 2004; Foley et al., 1997, 2000). In contrast, a bis(chelate) structure was found for the closely related germylene [MeC(NPri)2]2Ge, which was also made from GeCl2(dioxane) and two equivalents of the corresponding lithium amidinate (colorless crystals, 81%). The same synthetic approach was used to make bis(amidinato) germanium(IV) dichlorides in high yields (83–95%) (Karsch et al., 1998).
In recent years, amidinate- and guanidinate-stabilized germylenes have become versatile building blocks for novel inorganic ring systems (Cabeza et al., 2013; Matioszek et al., 2012; Yeong et al., 2012), coordination compounds (Jones et al., 2008; Brück et al., 2012), and MOCVD precursors for GST thin-layer deposition (Chen et al., 2007, 2009, 2010). Different reaction products have been isolated from germanium amidinates and chalcogens or chalcogen atom sources. For example, rapid oxidative addition of styrene sulfide or elemental selenium to the germylene derivatives resulted in a series of rare terminal chalcogenido complexes with the formulas [RC(NCy)2]2Ge═E (R = Me, tBu; E = S, Se). In a similar manner the amidinato-amido analogues [RC(NCy)2][N(SiMe3)2]Ge═Se (R = Me, But) have been obtained. An X-ray structure determination of the acetamidinate derivative [MeC(NCy)2][N(SiMe3)2]Ge═Se confirmed the presence of a terminal Ge═Se bond (Foley et al., 1997, 2000). More recently the synthesis and characterization of the amidinate-stabilized bis(germylene) oxide and sulfide LGe—E—GeL (E = O, S; L = tBuC(NAr)2, Ar = 2,6-iPr2C6H3) have been described. The bis(germylene) oxide was prepared by the reaction of 2 equiv. of LGeCl with Me3NO and 2 equiv. of KC8 in THF. It has been proposed that the reaction proceeds through an LGeI intermediate, which then reacts with Me3NO to form LGe—O—GeL. Similarly, the reaction of two equivalents of LGeCl with elemental sulfur and two equivalents of KC8 in THF afforded LGe—S—GeL (Zhang et al., 2011).
To the best of our knowledge, dimeric bis(amidinato)germanium(IV) oxides have not yet been reported in the literature. Such a compound has now been serendipitously obtained in the course of our ongoing investigation of the use of germanium amidinates and guanidinates as new precursors for GST thin-layer deposition. The X-ray crystal structure determination revealed the presence of a C2-symmetric dimer of the composition [(µ-O)Ge{k1N-N,N'-MeC(NiPr)(=NiPr)}{k2N,N'-N,N' –MeC(NiPr)2}]2 comprising an almost planar (r.m.s.d. 0.039 Å) central four-membered Ge2O2 ring (Fig. 1). The independent Ge—O distances are 1.7797 (8) and 1.8568 (8) Å, with an average of 1.8183 Å lying between the Ge—O bond lengths of 1.733 (4) and 1.766 (5) Å in LGe—O—GeL (L = tBuC(NAr)2, Ar = 2,6-iPr2C6H3) (Zhang et al., 2011) and that in (Mamx)GeOiPr (Mamx = methylaminomethyl-m-xylyl) of 1.856 (2) Å (Jutzi et al., 1999). In contrast to the germylene precursor [MeC(NiPr)2]2Ge, in which both amidinate ligands are N,N'-chelating, each Ge atom in the title compound contains one N,N'-chelating and one k1-coordinated ("dangling") amidinate ligand. The overall C2 symmetry of the dimeric molecule allows the monodentate amidinate ligands to be arranged in a cisoid fashion. The germanium centres adopt a distorted trigonal-bipyramidal geometry, with a bridging oxygen and one N atom of the chelating amidinate arranged in the axial positions (N2—Ge1—O1i 157.00 (3)°). The angle sum around Ge in the equatorial plane (O1, N1, N3) is 358.2 (5)°. The chelating amidinate shows a small bite angle N1—Ge—N2 of 64.80 (4)°, which is typical of this type of heteroallylic ligand (Edelmann 2008, 2013). The C—N bond lengths in the chelating amidinate (C1—N2 1.3038 (15) Å, C1—N1 1.3512 (14) Å) lie approximately between the values for C═N double bonds and C—N(sp2) single bonds. In the monodentate amidinate ligand, the difference between the formal C═N double bond (N4 disordered: C9—N4 1.281 (12), 1.299 (12) Å) and the C—N(sp2) single bond (C9—N3 1.3816 (14) Å) is more significant.