Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270104008741/fg1750sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270104008741/fg1750Isup2.hkl |
CCDC reference: 243576
A solution of KTp (25.2 mg, 0.1 mmol) in acetonitrile (3 ml) was added dropwise to a solution of (Et4N)FeCl4(32.5 mg, 0.1 mmol) in acetonitrile (2 ml). The mixture was stirred at room temperature for 15 h. Solid KSCN (48.6 mg, 0.5 mmol) was added to the mixture, which was stirred for another 15 h and then filtered?. Red crystals of (I) suitable for X-ray analysis were obtained by slow diffusion of ether into the filtrate. IR (KBr pellet): 2508 (B—H), 2069, 2029 (CN) cm−1.
All H atoms were identified in difference maps and were included in the refinement in the riding-motion approximation [C—H = 0.93 Å, B—H = 0.98 Å and Uiso(H) = 1.2Ueq(carrier atom)].
Data collection: SMART (Bruker, 2000); cell refinement: SMART; data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXTL (Bruker, 2000); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek 2003).
[Fe(C9H10BN6)2]3[Fe(NCS)6] | Dx = 1.531 Mg m−3 |
Mr = 1850.12 | Mo Kα radiation, λ = 0.71073 Å |
Trigonal, R3 | Cell parameters from 531 reflections |
Hall symbol: -R 3 | θ = 2.1–19.0° |
a = 22.676 (2) Å | µ = 0.93 mm−1 |
c = 13.5195 (18) Å | T = 293 K |
V = 6020.3 (12) Å3 | Block, red |
Z = 3 | 0.3 × 0.25 × 0.25 mm |
F(000) = 2832 |
Bruker SMART APEX CCD area-detector diffractometer | 2638 independent reflections |
Radiation source: sealed tube | 1915 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.044 |
ϕ and ω scans | θmax = 26.0°, θmin = 1.8° |
Absorption correction: multi-scan (SADABS; Bruker, 2000) | h = −27→25 |
Tmin = 0.76, Tmax = 0.79 | k = −25→27 |
11418 measured reflections | l = −9→16 |
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)] = 0.044 | H-atom parameters constrained |
wR(F2) = 0.104 | w = 1/[σ2(Fo2) + (0.0526P)2] where P = (Fo2 + 2Fc2)/3 |
S = 1.11 | (Δ/σ)max = 0.002 |
2638 reflections | Δρmax = 0.25 e Å−3 |
181 parameters | Δρmin = −0.38 e Å−3 |
0 restraints | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.00035 (9) |
[Fe(C9H10BN6)2]3[Fe(NCS)6] | Z = 3 |
Mr = 1850.12 | Mo Kα radiation |
Trigonal, R3 | µ = 0.93 mm−1 |
a = 22.676 (2) Å | T = 293 K |
c = 13.5195 (18) Å | 0.3 × 0.25 × 0.25 mm |
V = 6020.3 (12) Å3 |
Bruker SMART APEX CCD area-detector diffractometer | 2638 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2000) | 1915 reflections with I > 2σ(I) |
Tmin = 0.76, Tmax = 0.79 | Rint = 0.044 |
11418 measured reflections |
R[F2 > 2σ(F2)] = 0.044 | 0 restraints |
wR(F2) = 0.104 | H-atom parameters constrained |
S = 1.11 | Δρmax = 0.25 e Å−3 |
2638 reflections | Δρmin = −0.38 e Å−3 |
181 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) | |
Fe1 | 0.3333 | 0.1667 | 0.1667 | 0.03438 (18) | |
N1 | 0.30355 (11) | 0.06967 (10) | 0.17187 (17) | 0.0401 (5) | |
N2 | 0.24385 (12) | 0.02658 (11) | 0.21572 (18) | 0.0456 (6) | |
N3 | 0.24097 (11) | 0.14203 (11) | 0.12715 (16) | 0.0385 (5) | |
N4 | 0.18712 (11) | 0.09164 (11) | 0.17580 (17) | 0.0417 (5) | |
N5 | 0.30681 (12) | 0.16151 (11) | 0.30428 (16) | 0.0401 (5) | |
N6 | 0.24618 (11) | 0.10961 (11) | 0.33499 (17) | 0.0415 (5) | |
C1 | 0.33152 (16) | 0.03381 (15) | 0.1414 (2) | 0.0490 (7) | |
H1 | 0.3728 | 0.0514 | 0.1081 | 0.059* | |
C2 | 0.28999 (15) | −0.03374 (15) | 0.1665 (3) | 0.0568 (8) | |
H2 | 0.2975 | −0.0698 | 0.1539 | 0.068* | |
C3 | 0.23555 (15) | −0.03615 (14) | 0.2136 (3) | 0.0538 (8) | |
H3 | 0.1987 | −0.0750 | 0.2400 | 0.065* | |
C4 | 0.21606 (16) | 0.16781 (15) | 0.0611 (2) | 0.0485 (7) | |
H4 | 0.2422 | 0.2034 | 0.0179 | 0.058* | |
C5 | 0.14615 (16) | 0.13392 (18) | 0.0665 (3) | 0.0588 (8) | |
H5 | 0.1163 | 0.1412 | 0.0283 | 0.071* | |
C6 | 0.12995 (15) | 0.08688 (17) | 0.1409 (2) | 0.0516 (8) | |
H6 | 0.0862 | 0.0567 | 0.1631 | 0.062* | |
C7 | 0.33558 (16) | 0.20125 (16) | 0.3823 (2) | 0.0476 (7) | |
H7 | 0.3780 | 0.2407 | 0.3824 | 0.057* | |
C8 | 0.29368 (18) | 0.17556 (18) | 0.4624 (2) | 0.0582 (8) | |
H8 | 0.3017 | 0.1938 | 0.5258 | 0.070* | |
C9 | 0.23720 (18) | 0.11723 (17) | 0.4303 (2) | 0.0535 (8) | |
H9 | 0.1995 | 0.0883 | 0.4683 | 0.064* | |
B1 | 0.20031 (17) | 0.05481 (17) | 0.2592 (3) | 0.0488 (8) | |
H11 | 0.1581 | 0.0191 | 0.2890 | 0.059* | |
Fe2 | 0.0000 | 0.0000 | 0.5000 | 0.0367 (2) | |
S1 | 0.15096 (4) | 0.20524 (4) | 0.32058 (6) | 0.0528 (2) | |
N7 | 0.06325 (12) | 0.08236 (12) | 0.41285 (19) | 0.0458 (6) | |
C10 | 0.09926 (14) | 0.13332 (14) | 0.37313 (18) | 0.0375 (6) | |
Cg1 | 0.10449 | 0.14031 | 0.36885 | 0.01* | 0 |
Cg2 | 0.18405 | 0.12446 | 0.11429 | 0.01* | 0 |
U11 | U22 | U33 | U12 | U13 | U23 | |
Fe1 | 0.0329 (3) | 0.0295 (3) | 0.0415 (3) | 0.0162 (2) | 0.0096 (2) | 0.0071 (2) |
N1 | 0.0397 (12) | 0.0285 (11) | 0.0547 (13) | 0.0191 (10) | 0.0120 (10) | 0.0066 (10) |
N2 | 0.0459 (14) | 0.0354 (12) | 0.0536 (14) | 0.0189 (11) | 0.0204 (11) | 0.0164 (10) |
N3 | 0.0360 (12) | 0.0388 (12) | 0.0459 (12) | 0.0226 (10) | 0.0057 (10) | 0.0066 (10) |
N4 | 0.0370 (12) | 0.0411 (13) | 0.0454 (13) | 0.0184 (11) | 0.0053 (10) | −0.0003 (10) |
N5 | 0.0489 (13) | 0.0364 (12) | 0.0376 (11) | 0.0233 (11) | 0.0095 (10) | 0.0058 (9) |
N6 | 0.0405 (12) | 0.0370 (12) | 0.0472 (13) | 0.0194 (10) | 0.0157 (10) | 0.0099 (10) |
C1 | 0.0502 (17) | 0.0454 (16) | 0.0563 (18) | 0.0275 (14) | 0.0074 (14) | 0.0012 (13) |
C2 | 0.0459 (17) | 0.0296 (15) | 0.097 (3) | 0.0203 (13) | −0.0038 (16) | −0.0049 (15) |
C3 | 0.0429 (17) | 0.0269 (14) | 0.086 (2) | 0.0132 (13) | 0.0154 (15) | 0.0089 (14) |
C4 | 0.0609 (19) | 0.0472 (17) | 0.0462 (17) | 0.0337 (15) | −0.0051 (14) | −0.0074 (13) |
C5 | 0.0530 (18) | 0.071 (2) | 0.065 (2) | 0.0401 (17) | −0.0210 (16) | −0.0176 (17) |
C6 | 0.0339 (15) | 0.0568 (18) | 0.0650 (19) | 0.0234 (14) | −0.0088 (14) | −0.0267 (16) |
C7 | 0.0491 (17) | 0.0465 (16) | 0.0461 (17) | 0.0232 (14) | −0.0019 (13) | −0.0039 (12) |
C8 | 0.077 (2) | 0.070 (2) | 0.0383 (16) | 0.045 (2) | 0.0036 (15) | −0.0016 (15) |
C9 | 0.067 (2) | 0.067 (2) | 0.0405 (15) | 0.0436 (18) | 0.0236 (14) | 0.0229 (14) |
B1 | 0.0390 (17) | 0.0428 (18) | 0.060 (2) | 0.0171 (15) | 0.0114 (16) | 0.0031 (16) |
Fe2 | 0.0341 (3) | 0.0341 (3) | 0.0417 (5) | 0.01706 (16) | 0.000 | 0.000 |
S1 | 0.0521 (5) | 0.0430 (4) | 0.0596 (5) | 0.0210 (4) | 0.0159 (4) | 0.0074 (3) |
N7 | 0.0428 (13) | 0.0414 (13) | 0.0520 (14) | 0.0202 (12) | 0.0052 (11) | 0.0117 (12) |
C10 | 0.0394 (14) | 0.0486 (17) | 0.0360 (14) | 0.0307 (13) | −0.0036 (11) | −0.0037 (12) |
Fe1—N5i | 1.941 (2) | C2—H2 | 0.9300 |
Fe1—N5 | 1.941 (2) | C3—H3 | 0.9300 |
Fe1—N3i | 1.953 (2) | C4—C5 | 1.375 (4) |
Fe1—N1 | 1.953 (2) | C4—H4 | 0.9300 |
Fe1—N3 | 1.953 (2) | C5—C6 | 1.375 (5) |
Fe1—N1i | 1.953 (2) | C5—H5 | 0.9300 |
N1—C1 | 1.322 (4) | C6—H6 | 0.9300 |
N1—N2 | 1.348 (3) | C7—C8 | 1.364 (4) |
N2—C3 | 1.339 (4) | C7—H7 | 0.9300 |
N2—B1 | 1.537 (4) | C8—C9 | 1.373 (5) |
N3—C4 | 1.337 (4) | C8—H8 | 0.9300 |
N3—N4 | 1.354 (3) | C9—H9 | 0.9300 |
N4—C6 | 1.333 (3) | B1—H11 | 0.9800 |
N4—B1 | 1.520 (4) | Fe2—N7ii | 2.063 (2) |
N5—C7 | 1.328 (4) | Fe2—N7iii | 2.063 (2) |
N5—N6 | 1.353 (3) | Fe2—N7iv | 2.063 (2) |
N6—C9 | 1.329 (4) | Fe2—N7v | 2.063 (2) |
N6—B1 | 1.543 (4) | Fe2—N7 | 2.063 (2) |
C1—C2 | 1.380 (4) | Fe2—N7vi | 2.063 (2) |
C1—H1 | 0.9300 | S1—C10 | 1.621 (3) |
C2—C3 | 1.366 (4) | N7—C10 | 1.161 (4) |
N5i—Fe1—N5 | 180.0 | N3—C4—C5 | 110.0 (3) |
N5i—Fe1—N3i | 89.39 (10) | N3—C4—H4 | 125.0 |
N5—Fe1—N3i | 90.61 (10) | C5—C4—H4 | 125.0 |
N5i—Fe1—N1 | 91.41 (9) | C4—C5—C6 | 105.0 (3) |
N5—Fe1—N1 | 88.59 (9) | C4—C5—H5 | 127.5 |
N3i—Fe1—N1 | 91.71 (9) | C6—C5—H5 | 127.5 |
N5i—Fe1—N3 | 90.61 (10) | N4—C6—C5 | 108.9 (3) |
N5—Fe1—N3 | 89.39 (10) | N4—C6—H6 | 125.5 |
N3i—Fe1—N3 | 180.0 | C5—C6—H6 | 125.5 |
N1—Fe1—N3 | 88.30 (9) | N5—C7—C8 | 109.9 (3) |
N5i—Fe1—N1i | 88.59 (9) | N5—C7—H7 | 125.1 |
N5—Fe1—N1i | 91.41 (9) | C8—C7—H7 | 125.1 |
N3i—Fe1—N1i | 88.30 (9) | C7—C8—C9 | 106.0 (3) |
N1—Fe1—N1i | 180.0 | C7—C8—H8 | 127.0 |
N3—Fe1—N1i | 91.70 (9) | C9—C8—H8 | 127.0 |
C1—N1—N2 | 107.9 (2) | N6—C9—C8 | 107.6 (3) |
C1—N1—Fe1 | 132.78 (19) | N6—C9—H9 | 126.2 |
N2—N1—Fe1 | 119.25 (16) | C8—C9—H9 | 126.2 |
C3—N2—N1 | 108.5 (2) | N4—B1—N2 | 106.8 (2) |
C3—N2—B1 | 132.2 (2) | N4—B1—N6 | 106.8 (2) |
N1—N2—B1 | 119.2 (2) | N2—B1—N6 | 105.9 (2) |
C4—N3—N4 | 107.1 (2) | N4—B1—H11 | 112.3 |
C4—N3—Fe1 | 133.2 (2) | N2—B1—H11 | 112.3 |
N4—N3—Fe1 | 119.61 (17) | N6—B1—H11 | 112.3 |
C6—N4—N3 | 109.1 (2) | N7ii—Fe2—N7iii | 89.39 (10) |
C6—N4—B1 | 132.0 (3) | N7ii—Fe2—N7iv | 90.61 (10) |
N3—N4—B1 | 118.8 (2) | N7iii—Fe2—N7iv | 180.0 |
C7—N5—N6 | 106.7 (2) | N7ii—Fe2—N7v | 89.39 (10) |
C7—N5—Fe1 | 133.5 (2) | N7iii—Fe2—N7v | 90.61 (10) |
N6—N5—Fe1 | 119.75 (18) | N7iv—Fe2—N7v | 89.39 (10) |
C9—N6—N5 | 109.8 (2) | N7ii—Fe2—N7 | 90.61 (10) |
C9—N6—B1 | 131.5 (3) | N7iii—Fe2—N7 | 89.39 (10) |
N5—N6—B1 | 118.6 (2) | N7iv—Fe2—N7 | 90.61 (10) |
N1—C1—C2 | 109.6 (3) | N7v—Fe2—N7 | 180.0 |
N1—C1—H1 | 125.2 | N7ii—Fe2—N7vi | 180.0 |
C2—C1—H1 | 125.2 | N7iii—Fe2—N7vi | 90.61 (10) |
C3—C2—C1 | 105.1 (3) | N7iv—Fe2—N7vi | 89.39 (10) |
C3—C2—H2 | 127.5 | N7v—Fe2—N7vi | 90.61 (10) |
C1—C2—H2 | 127.5 | N7—Fe2—N7vi | 89.39 (10) |
N2—C3—C2 | 108.9 (3) | C10—N7—Fe2 | 172.1 (2) |
N2—C3—H3 | 125.6 | N7—C10—S1 | 178.3 (3) |
C2—C3—H3 | 125.6 | ||
N5i—Fe1—N1—C1 | 46.2 (3) | Fe1—N5—N6—C9 | −177.73 (19) |
N5—Fe1—N1—C1 | −133.8 (3) | C7—N5—N6—B1 | 179.5 (2) |
N3i—Fe1—N1—C1 | −43.2 (3) | Fe1—N5—N6—B1 | 1.3 (3) |
N3—Fe1—N1—C1 | 136.8 (3) | N2—N1—C1—C2 | −0.7 (3) |
N5i—Fe1—N1—N2 | −135.5 (2) | Fe1—N1—C1—C2 | 177.8 (2) |
N5—Fe1—N1—N2 | 44.5 (2) | N1—C1—C2—C3 | 0.1 (4) |
N3i—Fe1—N1—N2 | 135.1 (2) | N1—N2—C3—C2 | −1.0 (4) |
N3—Fe1—N1—N2 | −44.9 (2) | B1—N2—C3—C2 | −179.2 (3) |
C1—N1—N2—C3 | 1.0 (3) | C1—C2—C3—N2 | 0.6 (4) |
Fe1—N1—N2—C3 | −177.7 (2) | N4—N3—C4—C5 | −0.4 (3) |
C1—N1—N2—B1 | 179.5 (3) | Fe1—N3—C4—C5 | −176.1 (2) |
Fe1—N1—N2—B1 | 0.8 (3) | N3—C4—C5—C6 | 1.1 (3) |
N5i—Fe1—N3—C4 | −48.0 (3) | N3—N4—C6—C5 | 1.3 (3) |
N5—Fe1—N3—C4 | 132.0 (3) | B1—N4—C6—C5 | 177.5 (3) |
N1—Fe1—N3—C4 | −139.4 (3) | C4—C5—C6—N4 | −1.4 (3) |
N1i—Fe1—N3—C4 | 40.6 (3) | N6—N5—C7—C8 | −0.5 (3) |
N5i—Fe1—N3—N4 | 136.69 (19) | Fe1—N5—C7—C8 | 177.3 (2) |
N5—Fe1—N3—N4 | −43.31 (19) | N5—C7—C8—C9 | 0.4 (4) |
N1—Fe1—N3—N4 | 45.30 (19) | N5—N6—C9—C8 | −0.2 (3) |
N1i—Fe1—N3—N4 | −134.70 (19) | B1—N6—C9—C8 | −179.1 (3) |
C4—N3—N4—C6 | −0.6 (3) | C7—C8—C9—N6 | −0.1 (4) |
Fe1—N3—N4—C6 | 175.87 (17) | C6—N4—B1—N2 | 128.1 (3) |
C4—N3—N4—B1 | −177.3 (2) | N3—N4—B1—N2 | −56.0 (3) |
Fe1—N3—N4—B1 | −0.9 (3) | C6—N4—B1—N6 | −118.9 (3) |
N3i—Fe1—N5—C7 | 45.1 (3) | N3—N4—B1—N6 | 57.0 (3) |
N1—Fe1—N5—C7 | 136.8 (3) | C3—N2—B1—N4 | −125.6 (3) |
N3—Fe1—N5—C7 | −134.9 (3) | N1—N2—B1—N4 | 56.3 (3) |
N1i—Fe1—N5—C7 | −43.2 (3) | C3—N2—B1—N6 | 120.8 (3) |
N3i—Fe1—N5—N6 | −137.26 (19) | N1—N2—B1—N6 | −57.2 (3) |
N1—Fe1—N5—N6 | −45.57 (19) | C9—N6—B1—N4 | 121.2 (3) |
N3—Fe1—N5—N6 | 42.74 (19) | N5—N6—B1—N4 | −57.5 (3) |
N1i—Fe1—N5—N6 | 134.43 (19) | C9—N6—B1—N2 | −125.2 (3) |
C7—N5—N6—C9 | 0.5 (3) | N5—N6—B1—N2 | 56.0 (3) |
Symmetry codes: (i) −x+2/3, −y+1/3, −z+1/3; (ii) −x+y, −x, z; (iii) y, −x+y, −z+1; (iv) −y, x−y, z; (v) −x, −y, −z+1; (vi) x−y, x, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
C9—H9···Cg1iii | 0.93 | 2.54 | 3.399 | 153 |
C5—H5···Cg2vii | 0.93 | 2.75 | 3.654 | 164 |
Symmetry codes: (iii) y, −x+y, −z+1; (vii) x−y, x, −z. |
Experimental details
Crystal data | |
Chemical formula | [Fe(C9H10BN6)2]3[Fe(NCS)6] |
Mr | 1850.12 |
Crystal system, space group | Trigonal, R3 |
Temperature (K) | 293 |
a, c (Å) | 22.676 (2), 13.5195 (18) |
V (Å3) | 6020.3 (12) |
Z | 3 |
Radiation type | Mo Kα |
µ (mm−1) | 0.93 |
Crystal size (mm) | 0.3 × 0.25 × 0.25 |
Data collection | |
Diffractometer | Bruker SMART APEX CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2000) |
Tmin, Tmax | 0.76, 0.79 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 11418, 2638, 1915 |
Rint | 0.044 |
(sin θ/λ)max (Å−1) | 0.617 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.044, 0.104, 1.11 |
No. of reflections | 2638 |
No. of parameters | 181 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.25, −0.38 |
Computer programs: SMART (Bruker, 2000), SMART, SAINT (Bruker, 2000), SHELXTL (Bruker, 2000), SHELXTL and PLATON (Spek 2003).
D—H···A | D—H | H···A | D···A | D—H···A |
C9—H9···Cg1i | 0.93 | 2.54 | 3.399 | 153 |
C5—H5···Cg2ii | 0.93 | 2.75 | 3.654 | 164 |
Symmetry codes: (i) y, −x+y, −z+1; (ii) x−y, x, −z. |
Poly(1-pyrazolyl)borato ligands [BHnPz(4-n)]− (Pz = 1-pyrazolyl) have become one of the most popular families of ligands in coordination chemistry since their introduction. When present in a tridentate coordination mode they are often considered as analogues to π-cyclopentadienyl groups, in that both kinds of ligands effectively occupy three facial coordination sites around a metal ion and are six-electron donors with one negative charge (Trofimenko, 1993). A large number of poly(pyrazolyl)borate complexes of main-group and transition metals have been prepared and these complexes have attracted much interest in organometallic, coordination and bioinorganic chemistry. For example, the [Cu(Tp)]2 [Tp is hydrotris(pyrazolyl)borate] dimer has been found to be useful as a starting material for bioinorganic modeling studies (Carrier et al., 1993).
Iron(III) complexes with these ligands are of interest, especially from the bioinorganic point of view, because the N3 coordination mimics the multiimidazole coordination often found at the active sites of non-heme iron proteins (Lippard, 1988). The synthesis and characterization of a binuclear iron complex, [Fe(III)2O(O2CCH3)2(Tp)2], as a synthetic analogue for methemerythrin is a good example (Armstrong, 1983; Armstrong et al., 1984). Iron(II) complexes with this kind of ligand are of special interest because of their unusual magnetic properties (Weldon et al., 2001). The Fe[HB(Pz)3]2, Fe[HB(3,5-Me2Pz)3]2 and Fe[HB(3,4,5-Me3Pz)3]2 complexes have been the subject of several variable-temperature Mössbauer spectral studies investigating spin-state transitions (Jesson et al., 1967; Long & Hutchinson, 1987; Grandjean et al., 1989).
We report here the synthesis and structure of the title complex, 3[Fe(III)(Tp)2]+·[Fe(III)(NCS)6]3−, (I) (Fig. 1), in the R3 space group. The asymmetric unit comprises half of an [Fe(Tp)2]+ cation, with its Fe atom on a crystallographic inversion centre, and one-sixth of an [Fe(NCS)6]3− anion, on a site of 3 symmetry. The structure of the [Fe(Tp)2]+ cation is very similar to that of Fe(Tp)2 (Oliver et al., 1980). The Fe atom is octahedrally coordinated to six N atoms of the two Tp ligands. The Fe—N(Tp) bond distances lie in the narrow range 1.941 (3)–1.953 (3) Å. The cis intraligand N—Fe—N bond angles are in the range 88.30 (9)–88.59 (9)°. The parameters in the anion compare favourably with those found for [NMe4]3[Fe(NCS)6] (Muller, 1977) {values for the [NMe4]+ salt are given in square brackets; Fe2–N7 = 2.063 (2) Å [2.03–2.06 Å], Fe2—N7—C10 = 172.1 (2)° [170–179°], N7—C10—S1 = 178.3 (3)° [178–179°], N7—C10 = 1.161 (4) Å [1.11–1.15 Å] and C10—S1 = 1.621 (3) Å [1.57–1.66 Å]. A search of the Cambridge Structural Database (Allen, 2002) for compounds that contain the hexa(isothiocyanato)iron(III) anion yielded only four hits. Of these, only one involved a metal complex as its cation (Coleman et al., 1988).
Increasing interest has developed recently in hydrogen bonds and other non-covalent interactions involving π acceptors (Ni et al., 2003; Li et al., 2003). Jeffrey (1997) mentions this possibility and classifies these interactions as weak hydrogen bonds. There are two types of weak C—H···π interactions in (I), which play an important role in the extended structure [Cg1 is the centre of gravity of the isothiocyanato group (Type I) and Cg2 is the centroid of the N3/N4/C5–C7 pyrazole ring (Type II); Table 1] Each Fe(NCS)63− ion is connected to six Fe(Tp)2+ units via the weak C—H···Cg1 interactions, while each [Fe(Tp)2]+ is connected to four neighbouring [Fe(Tp)2]+ moieties via C—H···Cg2 interactions and to two Fe(NCS)63− units via weak C—H···Cg1 interactions. Thus the alternating cations and anions are stacked together into an extended three-dimensional network.
In order to describe this structure in detail, we chose one layer parallel to the (10–1) plane. As shown in Fig. 2, there are two kinds of environments for the [Fe(Tp)2]+ ion. In one, each [Fe(Tp)2]+ ion is connected to two [Fe(Tp)2]+ ions via Type II interactions and to two Fe(NCS)63− ions via Type I interactions; in the other, each [Fe(Tp)2]+ is connected to four [Fe(Tp)2]+ ions via Type II interactions. Each Fe(NCS)63− ion is connected to four [Fe(Tp)2]+ ions via the Type I interaction. Thus Type II interactions exists only between the [Fe(Tp)2]+ units, and Type I interactions occur between the [Fe(Tp)2]+ and the Fe(NCS)63− ions. The layers are connected by the two types of weak C—H···π interactions, thus forming a three-dimensional network.