In the quasi-trigonal-bipyramidal environment of the five-coordinate FeII atom in the title compound, [FeCl2(C14H18N6O)(CH4O)], the methanol and one of the N-atom donors of the potentially tridentate ligand are disposed axially: Fe-N(axial) is 2.149 (2) Å, Fe-N(equatorial) is 2.108 (2) Å and N-Fe-O is 174.14 (7)°.
Supporting information
CCDC reference: 245850
A solution of (mim)3COMe (0.057 g, 0.20 mmol) in methanol (5 ml) was added to a stirred solution of iron(II) chloride (0.029 g, 0.23 mmol) in methanol (5 ml). Diethyl ether (65 ml) was allowed to diffuse into the pale-yellow solution. After 1 d, a small amount of a colourless precipitate formed; the yellow supernatant was cannula filtered and light petroleum (313–333 K, 70 ml) was added. After 2 d, a yellow crystalline material was obtained. This was cannula filtered and the yellow crystals of (I) were washed with diethyl ether (3 × 2 ml).
The hydroxyl H atom was refined freely. The remaining H atoms were located in difference Fourier maps and placed in idealized positions, with C—H = 0.95 Å, and with Uiso(H) = 1.25Ueq(C) for CH or 1.5Ueq(C) for CH3. The largest peak in the final difference map was located 0.71 Å from the Fe atom.
Data collection: SMART (Siemens, 1995); cell refinement: SAINT (Siemens, 1995); data reduction: SAINT; program(s) used to solve structure: Xtal3.5 (Hall et al., 1995); program(s) used to refine structure: CRYLSQ in Xtal3.5; molecular graphics: Xtal3.5; software used to prepare material for publication: BONDLA and CIFIO in Xtal3.5.
Dichloro(methanol-
κO)[(methoxy)tris(1-methyl-1
H-imidazol-2-yl)methane-
κ2N3]iron(II)
top
Crystal data top
[FeCl2(C14H18N6O)(CH4O)] | F(000) = 920 |
Mr = 445.13 | Dx = 1.53 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -p 2yn | Cell parameters from 8192 reflections |
a = 9.8803 (8) Å | θ = 2.5–37.3° |
b = 16.329 (1) Å | µ = 1.08 mm−1 |
c = 12.246 (1) Å | T = 150 K |
β = 101.953 (2)° | Prism, yellow |
V = 1932.9 (3) Å3 | 0.3 × 0.25 × 0.2 mm |
Z = 4 | |
Data collection top
Bruker SMART CCD area-detector diffractometer | 10108 independent reflections |
Radiation source: sealed tube | 6646 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.063 |
ω scans | θmax = 37.6°, θmin = 2.1° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −16→16 |
Tmin = 0.572, Tmax = 0.806 | k = −27→27 |
39725 measured reflections | l = −20→20 |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.054 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.157 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.27 | w = 1/[σ2(F2) + 2.6F2] |
6646 reflections | (Δ/σ)max = 0.01 |
239 parameters | Δρmax = 1.77 e Å−3 |
0 restraints | Δρmin = −0.78 e Å−3 |
0 constraints | |
Crystal data top
[FeCl2(C14H18N6O)(CH4O)] | V = 1932.9 (3) Å3 |
Mr = 445.13 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 9.8803 (8) Å | µ = 1.08 mm−1 |
b = 16.329 (1) Å | T = 150 K |
c = 12.246 (1) Å | 0.3 × 0.25 × 0.2 mm |
β = 101.953 (2)° | |
Data collection top
Bruker SMART CCD area-detector diffractometer | 10108 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 6646 reflections with I > 2σ(I) |
Tmin = 0.572, Tmax = 0.806 | Rint = 0.063 |
39725 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.054 | 0 restraints |
wR(F2) = 0.157 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.27 | Δρmax = 1.77 e Å−3 |
6646 reflections | Δρmin = −0.78 e Å−3 |
239 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
Fe | 0.22512 (3) | 0.113206 (19) | 0.20735 (3) | 0.01858 (12) | |
Cl1 | 0.35746 (6) | −0.00288 (3) | 0.26351 (5) | 0.0269 (2) | |
Cl2 | −0.01074 (6) | 0.11563 (4) | 0.12920 (5) | 0.0266 (2) | |
N11 | 0.2875 (2) | 0.12109 (12) | 0.04964 (17) | 0.0229 (7) | |
C12 | 0.3696 (2) | 0.17360 (12) | 0.01248 (17) | 0.0179 (7) | |
N13 | 0.4067 (2) | 0.14389 (12) | −0.08172 (17) | 0.0234 (8) | |
C131 | 0.4942 (3) | 0.17943 (18) | −0.1526 (3) | 0.0357 (12) | |
C14 | 0.3457 (3) | 0.06826 (16) | −0.1025 (2) | 0.0303 (10) | |
C15 | 0.2720 (3) | 0.05523 (16) | −0.0219 (2) | 0.0304 (10) | |
N21 | 0.3343 (2) | 0.22428 (11) | 0.24200 (15) | 0.0182 (6) | |
C22 | 0.3900 (2) | 0.27337 (12) | 0.17655 (16) | 0.0162 (6) | |
N23 | 0.4331 (2) | 0.34435 (11) | 0.23072 (15) | 0.0193 (6) | |
C231 | 0.4984 (3) | 0.41604 (15) | 0.1914 (2) | 0.0293 (10) | |
C24 | 0.4037 (3) | 0.33991 (15) | 0.33525 (18) | 0.0235 (8) | |
C25 | 0.3424 (2) | 0.26608 (14) | 0.34158 (17) | 0.0214 (8) | |
N31 | 0.39951 (19) | 0.35989 (12) | −0.09694 (14) | 0.0184 (6) | |
C32 | 0.3426 (2) | 0.32225 (12) | −0.02127 (15) | 0.0159 (6) | |
N33 | 0.20802 (18) | 0.34512 (11) | −0.03027 (15) | 0.0175 (6) | |
C331 | 0.1107 (2) | 0.32067 (16) | 0.0391 (2) | 0.0243 (9) | |
C34 | 0.1786 (2) | 0.40064 (14) | −0.11668 (18) | 0.0215 (8) | |
C35 | 0.2962 (2) | 0.40872 (14) | −0.15686 (18) | 0.0217 (8) | |
C1 | 0.4155 (2) | 0.25780 (12) | 0.05945 (16) | 0.0159 (6) | |
O11 | 0.55884 (15) | 0.26877 (10) | 0.06121 (14) | 0.0191 (6) | |
C11 | 0.6467 (2) | 0.21387 (17) | 0.1356 (2) | 0.0294 (10) | |
O10 | 0.16534 (18) | 0.11862 (12) | 0.37411 (15) | 0.0242 (7) | |
C10 | 0.2313 (3) | 0.0819 (2) | 0.4763 (2) | 0.0306 (11) | |
H131A | 0.49681 | 0.14438 | −0.21551 | 0.07000* | |
H131B | 0.45738 | 0.23124 | −0.17965 | 0.07000* | |
H131C | 0.58507 | 0.18638 | −0.11023 | 0.07000* | |
H14 | 0.35404 | 0.03207 | −0.16101 | 0.02900* | |
H15 | 0.21790 | 0.00803 | −0.01663 | 0.04400* | |
H231A | 0.50103 | 0.45964 | 0.24303 | 0.07200* | |
H231B | 0.59055 | 0.40284 | 0.18523 | 0.07200* | |
H231C | 0.44730 | 0.43302 | 0.12078 | 0.07200* | |
H24 | 0.42258 | 0.38021 | 0.39221 | 0.03100* | |
H25 | 0.31021 | 0.24628 | 0.40463 | 0.03700* | |
H331A | 0.02135 | 0.34042 | 0.00667 | 0.04200* | |
H331B | 0.10846 | 0.26247 | 0.04370 | 0.04200* | |
H331C | 0.13940 | 0.34292 | 0.11168 | 0.04200* | |
H34 | 0.09318 | 0.42787 | −0.14282 | 0.02700* | |
H35 | 0.30596 | 0.44314 | −0.21731 | 0.03100* | |
H11A | 0.74048 | 0.22418 | 0.13314 | 0.04900* | |
H11B | 0.62369 | 0.15902 | 0.11313 | 0.04900* | |
H11C | 0.63322 | 0.22189 | 0.20940 | 0.04900* | |
H10 | 0.085 (4) | 0.132 (2) | 0.383 (3) | 0.032 (10)* | |
H10A | 0.32144 | 0.06306 | 0.47238 | 0.05000* | |
H10B | 0.24102 | 0.12170 | 0.53583 | 0.05000* | |
H10C | 0.17790 | 0.03753 | 0.49415 | 0.05000* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Fe | 0.01822 (13) | 0.01754 (13) | 0.02112 (14) | −0.00124 (10) | 0.00671 (10) | 0.00145 (10) |
Cl1 | 0.0258 (2) | 0.0198 (2) | 0.0354 (3) | 0.00360 (17) | 0.0065 (2) | −0.0007 (2) |
Cl2 | 0.0195 (2) | 0.0395 (3) | 0.0208 (2) | −0.0023 (2) | 0.00449 (16) | 0.0045 (2) |
N11 | 0.0270 (8) | 0.0208 (8) | 0.0235 (8) | −0.0065 (6) | 0.0113 (7) | −0.0035 (6) |
C12 | 0.0192 (8) | 0.0180 (7) | 0.0178 (7) | −0.0005 (6) | 0.0070 (6) | −0.0018 (6) |
N13 | 0.0288 (9) | 0.0199 (8) | 0.0245 (8) | −0.0041 (6) | 0.0122 (7) | −0.0058 (6) |
C131 | 0.0465 (16) | 0.0311 (12) | 0.0387 (13) | −0.0091 (11) | 0.0301 (13) | −0.0112 (10) |
C14 | 0.0382 (13) | 0.0243 (10) | 0.0319 (11) | −0.0068 (9) | 0.0153 (10) | −0.0122 (9) |
C15 | 0.0398 (13) | 0.0236 (10) | 0.0313 (11) | −0.0124 (9) | 0.0155 (10) | −0.0098 (9) |
N21 | 0.0200 (7) | 0.0191 (7) | 0.0164 (6) | −0.0007 (6) | 0.0059 (5) | 0.0002 (5) |
C22 | 0.0168 (7) | 0.0168 (7) | 0.0155 (7) | −0.0015 (6) | 0.0044 (6) | −0.0002 (6) |
N23 | 0.0233 (8) | 0.0172 (7) | 0.0173 (7) | −0.0014 (6) | 0.0041 (6) | −0.0017 (6) |
C231 | 0.0404 (13) | 0.0195 (9) | 0.0297 (11) | −0.0099 (9) | 0.0110 (10) | −0.0021 (8) |
C24 | 0.0293 (10) | 0.0237 (9) | 0.0181 (8) | −0.0013 (8) | 0.0062 (7) | −0.0043 (7) |
C25 | 0.0255 (9) | 0.0234 (9) | 0.0161 (7) | 0.0001 (7) | 0.0063 (7) | −0.0006 (7) |
N31 | 0.0190 (7) | 0.0202 (7) | 0.0161 (7) | 0.0005 (6) | 0.0041 (5) | 0.0013 (5) |
C32 | 0.0154 (7) | 0.0174 (7) | 0.0146 (7) | 0.0012 (5) | 0.0026 (5) | −0.0004 (6) |
N33 | 0.0143 (6) | 0.0186 (7) | 0.0195 (7) | 0.0014 (5) | 0.0033 (5) | −0.0011 (6) |
C331 | 0.0153 (8) | 0.0304 (10) | 0.0282 (10) | 0.0005 (7) | 0.0070 (7) | 0.0005 (8) |
C34 | 0.0197 (8) | 0.0215 (9) | 0.0213 (8) | 0.0042 (7) | −0.0003 (6) | 0.0003 (7) |
C35 | 0.0259 (9) | 0.0200 (8) | 0.0178 (8) | 0.0011 (7) | 0.0019 (7) | 0.0017 (7) |
C1 | 0.0151 (7) | 0.0157 (7) | 0.0173 (7) | 0.0003 (5) | 0.0044 (5) | −0.0008 (6) |
O11 | 0.0127 (5) | 0.0204 (6) | 0.0243 (7) | 0.0008 (5) | 0.0040 (5) | 0.0030 (5) |
C11 | 0.0183 (9) | 0.0298 (11) | 0.0378 (12) | 0.0067 (8) | 0.0002 (8) | 0.0079 (9) |
O10 | 0.0209 (7) | 0.0322 (9) | 0.0214 (7) | 0.0056 (6) | 0.0087 (5) | 0.0070 (6) |
C10 | 0.0306 (11) | 0.0410 (14) | 0.0214 (9) | 0.0091 (10) | 0.0079 (8) | 0.0092 (9) |
Geometric parameters (Å, º) top
Fe—Cl1 | 2.3246 (7) | C24—C25 | 1.359 (3) |
Fe—Cl2 | 2.3290 (6) | C24—H24 | 0.949 |
Fe—N11 | 2.149 (2) | C25—H25 | 0.950 |
Fe—N21 | 2.1080 (18) | N31—C32 | 1.330 (3) |
Fe—O10 | 2.242 (2) | N31—C35 | 1.381 (3) |
N11—C12 | 1.324 (3) | C32—N33 | 1.363 (3) |
N11—C15 | 1.376 (3) | C32—C1 | 1.519 (3) |
C12—N13 | 1.370 (3) | N33—C331 | 1.464 (3) |
C12—C1 | 1.523 (3) | N33—C34 | 1.378 (3) |
N13—C131 | 1.465 (4) | C331—H331A | 0.946 |
N13—C14 | 1.375 (3) | C331—H331B | 0.953 |
C131—H131A | 0.964 | C331—H331C | 0.948 |
C131—H131B | 0.953 | C34—C35 | 1.359 (4) |
C131—H131C | 0.947 | C34—H34 | 0.949 |
C14—C15 | 1.358 (5) | C35—H35 | 0.950 |
C14—H14 | 0.946 | C1—O11 | 1.423 (3) |
C15—H15 | 0.948 | O11—C11 | 1.435 (3) |
N21—C22 | 1.331 (3) | C11—H11A | 0.949 |
N21—C25 | 1.385 (3) | C11—H11B | 0.951 |
C22—N23 | 1.359 (3) | C11—H11C | 0.949 |
C22—C1 | 1.528 (3) | O10—C10 | 1.418 (3) |
N23—C231 | 1.465 (3) | O10—H10 | 0.85 (5) |
N23—C24 | 1.372 (3) | C10—H10A | 0.953 |
C231—H231A | 0.949 | C10—H10B | 0.967 |
C231—H231B | 0.954 | C10—H10C | 0.948 |
C231—H231C | 0.948 | | |
| | | |
Cl1—Fe—Cl2 | 126.09 (3) | N23—C24—H24 | 127.0 |
Cl1—Fe—N11 | 93.80 (6) | C25—C24—H24 | 126.5 |
Cl1—Fe—N21 | 114.14 (5) | N21—C25—C24 | 109.4 (2) |
Cl1—Fe—O10 | 90.05 (5) | N21—C25—H25 | 125.4 |
Cl2—Fe—N11 | 94.50 (6) | C24—C25—H25 | 125.2 |
Cl2—Fe—N21 | 119.66 (5) | C32—N31—C35 | 105.32 (18) |
Cl2—Fe—O10 | 86.77 (5) | N31—C32—N33 | 111.30 (17) |
N11—Fe—N21 | 84.22 (8) | N31—C32—C1 | 124.15 (18) |
N11—Fe—O10 | 174.14 (7) | N33—C32—C1 | 124.43 (18) |
N21—Fe—O10 | 90.17 (7) | C32—N33—C331 | 128.69 (17) |
Fe—N11—C12 | 131.13 (15) | C32—N33—C34 | 106.84 (18) |
Fe—N11—C15 | 120.71 (18) | C331—N33—C34 | 124.41 (18) |
C12—N11—C15 | 106.4 (2) | N33—C331—H331A | 109.4 |
N11—C12—N13 | 110.50 (19) | N33—C331—H331B | 109.4 |
N11—C12—C1 | 127.6 (2) | N33—C331—H331C | 109.5 |
N13—C12—C1 | 121.8 (2) | H331A—C331—H331B | 109.5 |
C12—N13—C131 | 130.7 (2) | H331A—C331—H331C | 109.5 |
C12—N13—C14 | 106.8 (2) | H331B—C331—H331C | 109.4 |
C131—N13—C14 | 122.4 (2) | N33—C34—C35 | 106.34 (19) |
N13—C131—H131A | 110.8 | N33—C34—H34 | 126.8 |
N13—C131—H131B | 109.2 | C35—C34—H34 | 126.8 |
N13—C131—H131C | 109.4 | N31—C35—C34 | 110.2 (2) |
H131A—C131—H131B | 108.7 | N31—C35—H35 | 124.9 |
H131A—C131—H131C | 109.2 | C34—C35—H35 | 124.9 |
H131B—C131—H131C | 109.5 | C12—C1—C22 | 114.25 (17) |
N13—C14—C15 | 106.7 (2) | C12—C1—C32 | 108.40 (15) |
N13—C14—H14 | 126.7 | C12—C1—O11 | 109.67 (17) |
C15—C14—H14 | 126.6 | C22—C1—C32 | 110.33 (16) |
N11—C15—C14 | 109.5 (2) | C22—C1—O11 | 108.77 (15) |
N11—C15—H15 | 125.6 | C32—C1—O11 | 105.01 (16) |
C14—C15—H15 | 124.9 | C1—O11—C11 | 113.58 (18) |
FE—N21—C22 | 130.94 (14) | O11—C11—H11A | 109.6 |
FE—N21—C25 | 122.34 (16) | O11—C11—H11B | 109.2 |
C22—N21—C25 | 106.13 (18) | O11—C11—H11C | 109.4 |
N21—C22—N23 | 110.28 (18) | H11A—C11—H11B | 109.5 |
N21—C22—C1 | 129.37 (18) | H11A—C11—H11C | 109.6 |
N23—C22—C1 | 120.26 (18) | H11B—C11—H11C | 109.5 |
C22—N23—C231 | 129.5 (2) | FE—O10—C10 | 128.84 (17) |
C22—N23—C24 | 107.74 (19) | FE—O10—H10 | 123 (3) |
C231—N23—C24 | 122.8 (2) | C10—O10—H10 | 106 (3) |
N23—C231—H231A | 109.5 | O10—C10—H10A | 110.9 |
N23—C231—H231B | 109.8 | O10—C10—H10B | 109.7 |
N23—C231—H231C | 110.2 | O10—C10—H10C | 110.5 |
H231A—C231—H231B | 109.1 | H10A—C10—H10B | 107.9 |
H231A—C231—H231C | 108.9 | H10A—C10—H10C | 109.6 |
H231B—C231—H231C | 109.3 | H10B—C10—H10C | 108.2 |
N23—C24—C25 | 106.5 (2) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O10—H10···N31i | 0.85 (5) | 1.90 (5) | 2.745 (3) | 169 (4) |
Symmetry code: (i) x−1/2, −y+1/2, z+1/2. |
Experimental details
Crystal data |
Chemical formula | [FeCl2(C14H18N6O)(CH4O)] |
Mr | 445.13 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 150 |
a, b, c (Å) | 9.8803 (8), 16.329 (1), 12.246 (1) |
β (°) | 101.953 (2) |
V (Å3) | 1932.9 (3) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 1.08 |
Crystal size (mm) | 0.3 × 0.25 × 0.2 |
|
Data collection |
Diffractometer | Bruker SMART CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.572, 0.806 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 39725, 10108, 6646 |
Rint | 0.063 |
(sin θ/λ)max (Å−1) | 0.858 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.054, 0.157, 1.27 |
No. of reflections | 6646 |
No. of parameters | 239 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 1.77, −0.78 |
Selected geometric parameters (Å, º) topFe—Cl1 | 2.3246 (7) | Fe—N21 | 2.1080 (18) |
Fe—Cl2 | 2.3290 (6) | Fe—O10 | 2.242 (2) |
Fe—N11 | 2.149 (2) | | |
| | | |
Cl1—Fe—Cl2 | 126.09 (3) | Cl2—Fe—N21 | 119.66 (5) |
Cl1—Fe—N11 | 93.80 (6) | Cl2—Fe—O10 | 86.77 (5) |
Cl1—Fe—N21 | 114.14 (5) | N11—Fe—N21 | 84.22 (8) |
Cl1—Fe—O10 | 90.05 (5) | N11—Fe—O10 | 174.14 (7) |
Cl2—Fe—N11 | 94.50 (6) | N21—Fe—O10 | 90.17 (7) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O10—H10···N31i | 0.85 (5) | 1.90 (5) | 2.745 (3) | 169 (4) |
Symmetry code: (i) x−1/2, −y+1/2, z+1/2. |
Tris(1-methyl-1H-imidazol-2yl)methanol, (mim)3COH, is a well known ligand displaying tridentate capability, as described in our accompanying paper [Batten et al., 2004a; see also references therein for examples in association with iron(II)]. Less well known is the counterpart ligand described here, in which the hydroxyl H atom is replaced by a methyl group, thus changing the bridgehead functionality to an ether rather than an alcohol. In association with iron(II), examples have been described in which (mim)3COH behaves in a bidentate or tridentate fashion; in contrast, with the present ligand all examples hitherto structurally characterized appear to have been solely bidentate. Some examples for complexes containing metals other than Fe are copper(I) (Sorrell & Borovik, 1987), copper(II) (Stibrany et al., 1996) and palladium(II) (Rüther et al., 2001), wherein the particular metal ions concerned commonly exhibit predilections for relatively low coordination numbers. In the copper(I) and palladium(II) complexes, the ligand, although three-coordinate, achieves that status by virtue of the third donor bridging in a binuclear array. In extending its coordination chemistry, we had it in mind to prepare a mononuclear species in which it was tridentate, and, given the facility with which this is achieved about iron(II) by reaction of (mim)3COH with the metal(II) chloride, the latter was reacted with the present ligand in methanol solution in a similar manner, and the resulting yellow crystals of the title compound, (I), were subjected to a single-crystal diffraction study, the results of which are reported here. \sch
The results of the X-ray study are consistent with formulation of the material as (I) (Fig. 1), with one formula unit (a neutral molecule), devoid of crystallographic symmetry, comprising the asymmetric unit of the structure. Remarkably, the iron(II) environment is quasi-trigonal-bipyramidal five-coordinate, the ligand being two- rather than three- coordinate, with one of the N donors (N11) axial and trans to the O-methanol. Interestingly (Table 1), Fe—N11 is longer than Fe—N21, despite the latter lying in an equatorial site, normally considered as more `crowded' and accommodating `bulky' ligands or lone pairs. The five-coordinate geometry, although unusual, is similar to that reported for iron(II) complexes of planar tridentate N donor ligands, e.g. FeCl2(2,6-(ArNHCH2)2C5H3N) (Ar is 2,6-Pri2C6H3; Britovsek et al., 2001).
The overall result is curious in a number of other aspects. The multidentate ligand occupies only two coordination sites, despite the obvious facility of the metal ion to accommodate similar tridentate ligands in a six-coordinate environment. Further, as our subsequent study shows, the presence of a pair of Cl− ligands about the same metal ion does not preclude the attainment of six-coordination in the presence of two rather similar N,N'-bidentate ligands (Batten et al., 2004b). While the sample size thus far is limited, we conjecture that the presence of the methyl group (rather than hydroxyl) at the ligand bridgehead may confer some degree of control on the relative disposition of the three heterocycles, precluding a tridentate conformation. We note the disposition of the uncoordinated heterocycle, with the substituent directed `inwards' toward the metal, possibly precluding six-coordination, and the inherent crowding about the ether grouping if the opposite disposition (in coordinating mode) is adopted. The present disposition is presumably assisted by the intermolecular hydrogen-bond from a neighbouring methanol hydroxyl (Table 1). A further point of possible relevance is the quasi-planarity of the chelate ring [χ2 for the C3N2Fe ring is 3475, with deviations for the atoms C1 Altered - please check, C12, C22, N11, N21 and Fe of −0.032 (3), 0.104 (2), −0.044 (4), −0.072 (8), 0.043 (2) and −0.104 (3) Å, respectively. The interplanar dihedral angles to the coordinated (im) C3N2 planes are 12.24 (9) and 3.71 (9)°, and the dihedral between the pair of coordinated (im) C3N2 planes is 15.1 (1)°.