Four Coordinate Iron(II) Complexes
0.254 g (84%) of 3. Anal. Calcd for C24H40FeP2: C, 64.58; H, 9.03.
Found: C, 64.74; H, 9.05. Magnetic susceptibility (benzene-d6):
µeff ) 2.9 µB. 1H NMR (benzene-d6): δ ) -35.8 (36, 18H,
P(CH3)3), -4.8 (20, 6H, CH3-p-C6H2), 20.5 (79, 12H, CH3-o-C6H2),
25.5 (25, 4H, C6H2).
orange solid identified as 10. Anal. Calcd for C28H46FeP2: C, 67.20;
H, 9.26. Found: C, 67.01; H, 8.75. Magnetic susceptibility
(benzene-d6): µeff ) 4.4 µB. 1H NMR (benzene-d6): δ ) 9.1 (302,
12H, C6H2-o-CH3), 18.4 (836, 6H, C6H2-p-CH3), 90.3, -94.1 (2060,
20 H, CH2CH3), 127.9 (520, 4H, PCH2CH2P).
Preparation of trans-(Et3P)2Fe(Mes)2 (4). This molecule was
prepared in a manner similar to that for 1 with 0.250 g (0.430 mmol)
of Fe2(Mes)4 and 0.201 g (1.7 mmol) of PEt3 yielding 0.318 g (70%)
of 4. Anal. Calcd for C30H52FeP2: C, 67.92; H, 9.88. Found: C,
68.82; H, 9.66. Magnetic susceptibility (benzene-d6): µeff ) 2.8
Preparation of (dppe)Fe(Mes)2 (11). This molecule was
prepared in a manner similar to that for 3 with 0.337 g (0.570 mmol)
of Fe2(Mes)4 and 0.457 g (1.2 mmol) of dppe yielding 0.594 g
(75%) of an orange solid identified as 11. Anal. Calcd for C44H46-
FeP2: C, 76.30; H, 6.69. Found: C, 76.27; H, 6.31. Magnetic
1
1
µB. H NMR (benzene-d6): δ, -35.2 (845, 8H, CH3CH2), -19.8
susceptibility (benzene-d6): µeff ) 3.7 µB. H NMR (benzene-d6)
(727.6, 12H, CH3CH2), -2.2 (1841, 6H, CH3-p-C6H2), 10.4 (936.6,
12H, CH3-o-C6H2), 27.6, (979.2, 4H, m-C6H2).
δ ) -3.7 (120, 6H, CH3-p-C6H2), 16.5 (153, 12H, CH3-o-C6H2),
92.1 (2904), 97.6 (2880), 103 (163, 8H), 132 (386, 4H).
Preparation of trans-(PhMe2P)2Fe(Mes)2 (5). A scintillation
vial was charged with 0.200 g (0.340 mmol) of Fe2(Mes)4 and
approximately 5 mL of diethyl ether. With stirring, 0.188 g (1.40
mmol) of PPhMe2 in approximately 3 mL of diethyl ether was added
at ambient temperature forming a deep red reaction mixture. An
orange precipitate formed over the course of 3 h. The solid was
collected by filtration and washed with pentane to afford 0.183 g
(78%) of 5. Anal. Calcd for C34H44FeP2: C, 71.58; H, 7.77.
Found: C, 71.53; H, 8.04. Magnetic susceptibility (benzene-d6):
µeff ) 2.7 µB. 1H NMR (benzene-d6) δ ) -33.5 (30.3, 12H, PC6H5-
(CH3)2), -5.33 (5.3, 6H, CH3-p-C6H2), 0.45 (14.3, 4H), 0.70 (23.4,
4H), 21.3 (74.6, 12H, CH3-o-C6H2), 24.7 (11.1, 4H, C6H2).
Preparation of trans-(PhEt2P)2Fe(Mes)2 (6). This molecule was
prepared in a manner similar to that for 5 with 0.500 g (0.850 mmol)
of Fe2(Mes)4 and 0.565 g (3.4 mmol) of PEt2Ph in 10 mL of diethyl
ether yielding 0.862 g (81%) of an orange powder identified as 6.
Anal. Calcd. for C38H52FeP2: C, 72.84; H, 8.36. Found: C, 72.43;
Preparation of (PhEt2P)2FeCl2 (13). A 50 mL round-bottomed
flask was charged with 0.363 g (2.90 mmol) of FeCl2, 1.0 g (6.0
mmol) of PhEt2P, and approximately 30 mL of toluene. A reflux
condenser and a 180° needle valve were attached, and the reaction
mixture was heated to reflux for 2 h. The reaction mixture was
transferred into the drybox and filtered through Celite. The toluene
was removed in vacuo, and the off-white residue was washed
several times with pentane and dried to afford 1.23 g (93%) of 13.
Magnetic susceptibility (benzene-d6): µeff ) 4.8 µB. 1H NMR
(benzene-d6): δ ) -2.6 (57.4, 2H, p-C6H5), 2.57 (435.5, 4H), 14.1
(61.5, 4H), 77.9 (1543, 20 H, C2H5).
Preparation of (PhEt2P)2FeBr2 (14). This molecule was
prepared in a manner similar to that for 13 with 0.156 g (0.720
mmol) of FeCl2, 0.250 g (1.5 mmol) of PhEt2P, and approximately
20 mL of toluene and afforded 0.302 mg (77%) of 14. Magnetic
1
susceptibility (benzene-d6): µeff ) 5.0 µB. H NMR (benzene-d6):
δ ) -3.4 (52.3, 2H, p-C6H5), 4.6 (356.2, 4H), 14.0 (52.6, 4H),
77.1 (648.6, 20 H, C2H5).
1
H, 7.97. Magnetic susceptibility (benzene-d6): µeff ) 2.7 µB. H
NMR (benzene-d6): δ ) -44.0 (232, 4H), -20.53 (151, 12H, CH3-
CH2), -4.0 (368, 6H, C6H2-p-CH3), -3.3 (495, 4H), 0.86 (197,
8H, CH3CH2), 9.1 (171, 2H, p-H-C6H5), 14.8 (262, 12H, C6H2-o-
CH3), 25.4 (185, 4H).
Procedure for a Typical Exchange Reaction. A J. Young NMR
tube was charged with 0.020 g (0.035 mmol) of 5 and approximately
1.0 mL of benzene-d6. Using a calibrated gas bulb, 2 equiv (0.070
mmol) of PMe3 was added at 77 K. The solution was thawed and
Preparation of trans-(Ph2MeP)2Fe(Mes)2 (7). This molecule
was prepared in a manner similar to that for 5 with 0.100 g (0.170
mmol) of Fe2(Mes)4 and 0.136 g (0.680 mmol) of PPh2Me yielding
0.183 g (78%) of a red solid identified as 7. Anal. Calcd for C44H48-
FeP2: C, 76.08; H, 6.96. Found: C, 75.69; H, 6.25. Magnetic
1
shaken and the H NMR spectrum recorded.
1H NMR Characterization of (py)2Fe(Mes)2. 1H NMR (benzene-
d6): δ ) -5.14 (77.2, CH, py), 23.40 (10.8, CH, p-py), 23.4 (127.1,
CH, py), 41.6 (752.3, CH3, o-C6H2), 112.5 (168.2, CH3, p-C6H2),
138 (270.6, CH, m-C6H2).
1
susceptibility (benzene-d6): µeff ) 2.8 µB. H NMR (benzene-d6):
1
1H NMR Characterization of (PhEt2P)2Fe(C6Cl5)2. H NMR
δ ) -7.0 (179, 8H), 2.2 (159, 12H, CH3-o-C6H2), 10.4 (169, 6H),
17.9 (184, 4H), 21.3 (167, 4H), 23.4 (72.5, 6H).
(benzene-d6): δ ) -53.0 (29.5, Ph), -18.5 (19.1, CH3), -7.9 (9.2,
Ph), 11.8 (16.6, p-Ph).
Preparation of [(EtO)3P]2Fe(Mes)2 (8). This molecule was
prepared in a manner similar to that for 5 with 0.235 g (0.390 mmol)
of Fe2(Mes)4 and 0.332 g (2.0 mmol) of P(OEt)3 yielding 0.287 g
(57%) of a red solid identified as 8. Magnetic susceptibility
Acknowledgment. We thank the Cornell Department of
Chemistry and Chemical Biology and the National Science
Foundation (CAREER Award to P.J.C.) for financial support.
P.J.C. also acknowledges the Research Corp. (Cottrell
Scholarship) and the Packard Foundation for a fellowship
in science and engineering. G.T.Y. acknowledges the Na-
tional Science Foundation (CHE-023488) and the Virginia
Tech ASPIRES program for each providing partial support
for the purchase of the SQUID magnetometer.
1
(benzene-d6): µeff ) 2.7 µB. H NMR (benzene-d6): δ ) -8.2
(43.6, 6H, CH3-p-C6H2), -4.1 (213.2, 30H, P(OCH2CH3)), 19.0
(51.0, 4H, C6H2), 32.4 (137, 12H, CH3-o-C6H2).
Preparation of (dmpe)Fe(Mes)2 (9). This molecule was pre-
pared in a manner similar to that for 5 with 0.047 g (0.080 mmol)
of Fe2(Mes)4 and 0.024 g (0.160 mmol) of dmpe yielding 0.058 g
(82%) of yellow solid identified as 9. Anal. Calcd for C24H38FeP2:
C, 64.87; H, 8.62. Found: C, 64.89; H, 8.63. Magnetic susceptibility
(Guoy balance): µeff ) 4.2 µB.
Preparation of (depe)Fe(Mes)2 (10). This molecule was pre-
pared in a manner similar to that for 5 with 0.250 g (0.425 mmol)
of Fe2(Mes)4 and 0.175 mg of depe yielding 0.332 g (79%) of an
Supporting Information Available: Crystallographic data for
trans-(PhEt2P)2Fe(C6Cl5)2, 3, 6, 9, and 11 (CIF, PDF). This material
IC048202+
Inorganic Chemistry, Vol. 44, No. 9, 2005 3111