Syntheses, molecular structures, and self-assemblies of SFe 3, S 2Fe 3, S 3Fe 5, SeFe 3, and Se 2Fe 3 clusters with chelating diaminocarbenes

Article abstract of DOI:10.1080/00958972.2015.1079312

The reactions of substituted thioureas and selenoureas with iron carbonyls have been systematically investigated, and five types of SFe3, S2Fe3, S3Fe5, SeFe3, and Se2Fe3 clusters with chelating diaminocarbenes have been synthesized and characterized by X-

Full text of DOI:10.1080/00958972.2015.1079312

Journal of Coordination Chemistry
ISSN: 0095-8972 (Print) 1029-0389 (Online) Journal homepage: http://www.tandfonline.com/loi/gcoo20
Syntheses, molecular structures, and self-
assemblies of SFe3, S2Fe3, S3Fe5, SeFe3, and Se2Fe3
clusters with chelating diaminocarbenes
Yao-Cheng Shi, Shuai Wang & Sun Xie
To cite this article: Yao-Cheng Shi, Shuai Wang & Sun Xie (2015) Syntheses, molecular
structures, and self-assemblies of SFe3, S2Fe3, S3Fe5, SeFe3, and Se2Fe3 clusters with
chelating diaminocarbenes, Journal of Coordination Chemistry, 68:21, 3852-3883, DOI:
10.1080/00958972.2015.1079312
To link to this article: http://dx.doi.org/10.1080/00958972.2015.1079312
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Date: 04 December 2015, At: 04:17

Journal of Coordination Chemistry, 2015
Vol. 68, No. 21, 3852–3883, http://dx.doi.org/10.1080/00958972.2015.1079312
Syntheses, molecular structures, and self-assemblies of SFe3,
S2Fe3, S3Fe5, SeFe3, and Se2Fe3 clusters with chelating
diaminocarbenes
YAO-CHENG SHI*, SHUAI WANG and SUN XIE
College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, PR China
(Received 24 March 2015; accepted 10 July 2015)
NHR
NHR
HN
HN
C
C
G
G
Fe(CO)
Fe(CO)
E
E
CO
E
(OC)3Fe
Fe(CO)3
Fe(CO)3
(OC)3Fe
NHR
Fe3(CO)12
(E = S, Se)
HN
GHNC(=E)NHR
C
G
Fe(CO)
S
S
CO
S
Fe(CO)3
Fe
CO
(OC)3Fe
Fe(CO)3
The reactions of substituted thioureas and selenoureas with iron carbonyls have been systematically
investigated, and five types of SFe3, S2Fe3, S3Fe5, SeFe3, and Se2Fe3 clusters with chelating
diaminocarbenes have been synthesized and characterized by X-ray crystallography. The reactions
of C3H5NHC(=S)NHAr with Fe3(CO)12 afford (μ3-S)Fe3(CO)7(μ-CO)(κ3C,C,C-C3H5NHCNHAr)
(1, Ar = Ph; 2, Ar = 4-H2NC6H4). In contrast, the reactions of (2-C5H4N)NHC(=S)NHN=CHAr
with Fe2(CO)9 form (μ3-S)2Fe3(CO)7(κ2N,C-(2-C5H4N)NHCNHN=CHAr) (3, Ar = Ph; 4,
Ar = 4-CH3C6H4). Likewise, reactions of GNHC(=S)NHC(=O)Ph with Fe3(CO)12 provide
(μ3-S)2Fe3(CO)7(κ2N,C-GNHCNHC(=O)Ph) (5, G = 2-C5H4N; 6, G = 2-C4H3N2) as well as
Fe3(CO)8(μ-CO)2(κ2N,C-(2-C4H3N2)NHCNHC(=O)Ph). The reaction of (2-C5H4N)NHC(=S)NH2
with Fe3(CO)12 gives (μ3-S)2Fe3(CO)7(κ2N,C-(2-C5H4N)NHCNH2) (7). The reactions of GNHC(=S)
NHPh with Fe3(CO)12 produce (μ3-S)2Fe3(CO)7(κ2N,C-GNHCNHPh) (8, G = 2-C5H4N; 9,
G = 2-C4H3N2). Analogously, (2-C5H4N)NHC(=S)NH(2-CH3C6H4) offers (μ3-S)2Fe3(CO)7(κ2N,C-
(2-C5H4N)NHCNH(2-CH3C6H4)) (10). However, (2-C5H4N)NHC(=S)NH(2-CH3OC6H4) generates
(μ3-S)2(μ4-S)Fe5(CO)10(μ-CO)2(κ2N,C-(2-C5H4N)NHCNH(2-CH3OC6H4)) (11). Furthermore, the
reactions of (2-C5H4N)NHC(=S)NHR with Fe3(CO)12 form (μ3-S)2(μ4-S)Fe5(CO)10(μ-CO)2(κ2N,C-
(2-C5H4N)NHCNHR) (12, R = 2-H2NC6H4; 13, R = 4-H2NC6H4; 14, R = 2-C5H4N). Surprisingly,
the reaction of (2-C5H4N)NHC(=S)NHC3H5 with Fe3(CO)12 leads to (μ3-S)2(μ4-S)Fe5(CO)10(μ-
CO)2(κ2N,C-(2-C5H4N)NHCNHC3H5) (15). The reaction of C3H5NHC(=Se)NHPh with Fe3(CO)12
affords (μ3-Se)Fe3(CO)7(μ-CO)(κ3C,C,C-C3H5NHCNHPh) (16) as well as [(κ2N,C-PhNCNHC3H5)
Fe2(CO)6(μ4-Se)Fe2(CO)6]2(μ4-Se). As with (2-C4H3N2)NHC(=S)NHPh, (2-C4H3N2)NHC(=Se)
*Corresponding author. Email: ycshi@yzu.edu.cn
© 2015 Taylor & Francis

Fe/S and Fe/Se clusters with diaminocarbenes
3853
NHPh offers (μ3-Se)2Fe3(CO)7(κ2N,C-(2-C4H3N2)NHCNHPh) (17). Unlike (2-C5H4N)NHC(=S)NH
(2-CH3OC6H4), (2-C5H4N)NHC(=Se)NH(2-CH3OC6H4) yields (μ3-Se)2Fe3(CO)7(κ2N,C-(2-C5H4N)
NHCNH(2-CH3OC6H4)) (18). By virtue of N–Hꢀ ꢀ ꢀN, N–Hꢀ ꢀ ꢀO, and C–Hꢀ ꢀ ꢀO intermolecular
hydrogen bonds along with other non-covalent interactions, these new organometallic clusters
exhibit interesting supramolecular structures.
Keywords: Fe/S cluster; Fe/Se cluster; Diaminocarbene; Thiourea; Selenourea
1. Introduction
Reactions of organosulfur compounds with iron carbonyls have received considerable
attention because of interesting chemistry of iron–sulfur cluster complexes [1–3], and
particularly because of their applications in biochemistry as models for the active sites of
nitrogenases [4, 5] and [FeFe] hydrogenases [6–8]. Reactions of thiols, RSH, with iron
carbonyls generally formed (μ-RS)2Fe2(CO)6, where the bridging thiolate acts as a three-
electron donor. Moreover, butterfly complexes could be obtained by treatment of disulfides,
RSSR, with iron carbonyls [9, 10]. The Fe2(CO)6 complexes might also be obtained by
treating the unstable intermediates [RSFe(CO)4]− generated from disulfides RSSR and
PPN+ or Et4N+ salts of the anion [HFe(CO)4]− with HBF4 [11, 12]. In contrast to RSH, in
refluxing THF, reactions of sodium alkanethiolates RSNa with Fe3(CO)12 afforded triiron
anions [Fe3(CO)9(μ3-SR)]−; protonation resulted in Fe3(CO)9(μ3-SR)(μ-H) [13]. However,
at room temperature, alkanethiolate salts, RSM (M = Li, Na, Et3NH, MgX), reacted with
Fe3(CO)12 to offer salts of Seyferth-type anions [(μ-RS)(μ-CO)Fe2(CO)6]− [14]. Their
chemistry has been extensively explored by Seyferth and Song [1, 14]. Reactions of vinyl-
sulfides RSCH=CH2 with Fe3(CO)12 in refluxing benzene yielded (μ-RS)(μ-CH=CH2)
Fe2(CO)6, where cleavage of a C–S bond occurred and the three-electron ethenyl ligand is
coordinated to the diiron core in a σ, π mode [15]. Similarly, in reactions of thioimidates,
RʹC(SR)=NPh (R = Rʹ = alkyl, aryl), with Fe3(CO)12, scission of a C–S bond gave (μ-RS)
(μ-RʹC=NPh)Fe2(CO)6, where the iminoacyl group is attached to the diiron core in a σ,n
manner [16]. Closely related to the hydrodesulfurization (HDS) reaction, reactions of
thiophenes, R2C4H2S, and benzothiophene with Fe3(CO)12 have been investigated by
Rauchfuss and Hirotsu [17]. Thiaferroles (R2C4H2S)Fe2(CO)6 and benzothiaferrole (C8H6S)
Fe2(CO)6 were obtained. Indeed, refluxing the thiaferroles in benzene led to the correspond-
ing desulfurized ferroles. Relying on the nature of the linking groups R and Rʹ, reactions of
cyclic dithioethers, (RSRʹ)S, with Fe2(CO)9 generated complexes of (μ-SRS)Fe2(CO)6 or
(μ-SRʹS)Fe2(CO)6 [18]. Analogously, cyclic dithioacetals CH2(SR)(SRʹ) reacted with
Fe(CO)5 under UV irradiation to afford (μ-κ2S,C-RSCH2)Fe2(CO)6(μ-SRʹ) as well as
(μ-SCH2S)Fe2(CO)6 [19]. Reactions of diaryl thioketones, ArC(=S)Ar, with Fe2(CO)9 or
Fe3(CO)12 have been studied by Alper and later by Weigand [20]. Complexes (μ-κ3C,
π-(ArʹCH(Ar)S))Fe2(CO)6 were obtained, where the Arʹ group is an ortho-metalated
Ar group and linked to the diiron core in a σ,π mode. Conversely, two types of Fe2(CO)6
complexes have been isolated from the reactions of thioesters ArC(=S)OR with Fe2(CO)9:
(μ-κ2C,O:κ2S-(ArCSOR))Fe2(CO)6 and (μ-κ3C,π:κ2S-(ArʹCH(OR)S))Fe2(CO)6, where the
Arʹ group is an ortho-metalated Ar group and bonded to the diiron core in a σ,π fashion
[21]. Reactions of thioamides RC(=S)NMe2 (R = Me, Ph) with Fe2(CO)9 gave both
(κS-(RCSNMe2))Fe(CO)4 and (μ-κ2C,N:κ2S-(RCSNMe2))Fe2(CO)6 [22]. Unlike the

3854
Y.-C. Shi et al.
thioesters and the thioamides, reactions of α,β-unsaturated thioamides and thioesters with
Fe(CO)5 or Fe2(CO)9 provided LFe(CO)3, with L as a four-electron donor being bonded via
a C=C bond and an S in a π,n mode [23]. Reactions of dithioesters RC(=S)SRʹ with
Fe2(CO)9 produced (μ-κ2C,S(Rʹ):κ2S-(RCSSRʹ))Fe2(CO)6, with the organic substrate retain-
ing its structural integrity and bonding to the diiron centers as a six-electron donor [24].
Similarly, dithioacids RC(=S)SH reacted with Fe3(CO)12 in the presence of Et3N at room
temperature to yield [Et3NH][(μ-RCS2)Fe2(CO)6]. Reactivity of the cluster salts toward
electrophiles has been investigated by Shi [25]. Interestingly, treating dithiocarbonates ROC
(=S)SRʹ with Fe2(CO)9 offered (μ-κ2C,S(Rʹ):κ2S-(ROCSSRʹ))Fe2(CO)6; further heating led
to (μ-RʹS)(μ-ROC=S)Fe2(CO)6, where cleavage of a C–S bond occurred with subsequent
formation of bridging, three-electron thiolate and thioacyl ligands [26]. Such a cleaving
reaction has been observed in the syntheses of other thiolate-bridged Fe2(CO)6 complexes
as well. Complexes (μ-RS)(μ-RSC=S)Fe2(CO)6 were formed from reactions of
trithiocarbonates, RSC(=S)SR, with Fe2(CO)9 [26(c), 26(e)]. Reactions of substituted
thioureas bearing alkyl and/or aryl group(s) with iron carbonyls have been studied by Alper
and coworkers [22, 23]. Depending on the nature of the thioureas, several products such as
(κS-L)Fe(CO)4,
(κS-L)2Fe(CO)3,
(μ-κ2C,N:κ2S-L)Fe2(CO)6,
and
(μ-Lʹ)2Fe2(CO)8
(Lʹ = deprotonated thiourea L) have been isolated and identified by EA, MS, and NMR.
However, so far, no results on other thioureas bearing potential donors have been reported.
Particularly, compared with thioureas, organometallic chemistry of selenoureas is still in its
infancy [27]. Considering these reasons and our longstanding interest in the chemistry of
Fe/S and Fe/Se clusters as model compounds of hydrogenases [28], we have investigated
the reactions of substituted thioureas and selenoureas with iron carbonyls. Here, we report
the syntheses, molecular structures, and self-assemblies of SFe3, S2Fe3, S3Fe5, SeFe3, and
Se2Fe3 clusters with chelating diaminocarbenes.
2. Experimental
2.1. General procedures
All reactions were carried out under N2 atmosphere with standard Schlenk techniques. All
solvents employed were dried by refluxing over appropriate drying agents and stored under
N2 atmosphere. THF was distilled from sodium-benzophenone; petroleum ether (60–90 °C)
and CH2Cl2 were distilled from P2O5. Fe2(CO)9 [29], Fe3(CO)12 [30], PhCONCS [31],
2-C5H4NNCS [32], C3H5NCS [33], PhNCSe [34], 2-CH3OC6H4NCSe [34], C3H5NHC(=S)
NHPh (TU1) [35], C3H5NHC(=S)NH(4-H2NC6H4) (TU2) [36], (2-C5H4N)NHC(=S)
NHN=CHPh (TU3) [37], (2-C5H4N)NHC(=S)NHN=CH(4-CH3C6H4) (TU4) [37],
(2-C5H4N)NHC(=S)NHC(=O)Ph (TU5) [38], (2-C4H3N2)NHC(=S)NHC(=O)Ph (TU6) [39],
(2-C5H4N)NHC(=S)NH2 (TU7) [40], (2-C5H4N)NHC(=S)NHPh (TU8) [41], (2-C4H3N2)
NHC(=S)NHPh (TU9) [42], (2-C5H4N)NHC(=S)NH(2-CH3C6H4) (TU10) [43], (2-C5H4N)
NHC(=S)NH(2-CH3OC6H4) (TU11) [43], (2-C5H4N)NHC(=S)NH(2-H2NC6H4) (TU12)
[44], (2-C5H4N)NHC(=S)NH(4-H2NC6H4) (TU13) [44], (2-C5H4N)NHC(=S)NH(2-C5H4N)
(TU14) [45], and (2-C5H4N)NHC(=S)NHC3H5 (TU15) [46] were prepared according to the
literature procedures and were identified by comparison of their melting points and IR spec-
tra with those of authentic samples. C3H5NHC(=Se)NHPh (SU1), (2-C4H3N2)NHC(=Se)
NHPh (SU2), and (2-C5H4N)NHC(=Se)NH(2-CH3OC6H4) (SU3) were synthesized by an

Fe/S and Fe/Se clusters with diaminocarbenes
3855
appropriate amine and isoselenocyanate of 1:1 ratio in 20 mL of CH2Cl2 at room
temperature for 4 h (see Supplementary Data) [34, 47]. The progress of all reactions was
monitored by TLC (silica gel H). NMR spectra were recorded on a Bruker Avance 600 or
Mercury 400 or Vx-300 spectrometer. Chemical shifts were reported in δ units (ppm) down-
1
field from internal tetramethylsilane for the H NMR spectra and for the 13C NMR spectra.
IR spectra were carried out on a Bruker Tensor 27 spectrometer as KBr disks from 400 to
4000 cm−1. Analyses for C, H, and N were performed on an Elementar Vario EL analyzer.
Melting points were measured on an SGW X-4 apparatus and are uncorrected.
2.2. Synthesis of 1
To a solution of TU1 (0.308 g, 1.6 mmol) in THF (15 mL) was added Fe3(CO)12 (0.806 g,
1.6 mmol). The mixture was stirred at room temperature for 24 h. After the solvent was
removed under vacuum, the residue was subjected to TLC separation using CH2Cl2/
petroleum ether (1:2, v/v) as eluent. From the first band, S2Fe3(CO)9 (0.075 g) was obtained
which was identified by comparison of its melting point and IR spectrum with those of an
authentic sample. From the second band, 1 was obtained as a brown solid (0.131 g, 14%).
Anal. Calcd for C18H12Fe3N2O8S (%): C, 37.03; H, 2.07; N, 4.80. Found: C, 37.29; H,
2.15; N, 4.67. IR (KBr): 3345 (w), 2054 (vs), 1997 (vs), 1964 (vs), 1936 (m), 1862 (m),
1
1556 (m), 573 (w), 538 (w) cm−1. H NMR (300 MHz, CDCl3, TMS): δ 7.61 (s, 1H, NH),
7.47–7.02 (m, 5H, ArH), 5.07 (s, 1H, NH), 4.32–4.31 (m, 2H, CH2), 4.10–4.08 (m, 1H,
CH), 3.74–2.06 (m, 2H, CH2). 13C NMR (75 MHz, CDCl3, TMS): δ 213.7, 209.0, 150.5,
131.5, 129.9, 126.8, 51.1.
2.3. Synthesis of 2
A mixture of TU2 (0.207 g, 1.0 mmol) and Fe3(CO)12 (0.756 g, 1.5 mmol) in THF
(15 mL) was stirred at room temperature for 24 h. After the solvent was removed in vacuo,
the residue was subjected to TLC separation using ethyl acetate/petroleum ether (1:1, v/v)
as eluent. From the first band, S2Fe3(CO)9 (0.057 g) was obtained. From the second band,
2 was obtained as a brown solid (0.065 g, 11%). Anal. Calcd for C18H13Fe3N3O8S (%): C,
36.10; H, 2.19; N, 7.02. Found: C, 36.02; H, 2.18; N, 7.03. IR (KBr): 3366 (w), 2060 (vs),
1
2004 (vs), 1958 (vs), 1863 (m), 1551 (m), 1512 (m), 575 (w), 542 (w) cm−1. H NMR
(600 MHz, CDCl3, TMS): δ 7.39 (s, 1H, NH), 6.78–6.62 (m, 4H, ArH), 5.95 (s, 1H, NH),
4.49–4.24 (m, 2H, CH2), 4.08–4.06 (m, 1H, CH), 3.84–3.81 (m, 2H, CH2), 1.32
(s, 2H, NH2).
2.4. Synthesis of 3
A mixture of TU3 (0.384 g, 1.5 mmol) and Fe2(CO)9 (1.637 g, 4.5 mmol) in 15 mL of
toluene was stirred at room temperature for 24 h. In the course of the reaction, the pale yel-
low suspension slowly changed to a deep black solution as the ligand and Fe2(CO)9 dis-
solved. After the reaction was complete, all volatile materials were removed in vacuo. The
residue was dissolved in CH2Cl2, 1 g of silica gel was added and the solvent was again
removed under reduced pressure. Chromatography on silica gel using petroleum ether/
CH2Cl2 (1:3, v/v) as eluent afforded a grass green band of 3 (0.212 g, 44%) and
S2Fe3(CO)9 (0.052 g) in increasing order of Rf values. Anal. Calcd for C20H12Fe3N4O7S2

3856
Y.-C. Shi et al.
(%): C, 36.84; H, 1.86; N, 8.59. Found: C, 36.71; H, 1.83; N, 8.68. IR (KBr): 3352 (m),
2923 (m), 2852 (m), 2057 (s), 2001 (vs), 1969 (vs), 1915 (s), 1610 (w), 1525 (m), 1261
(w), 808 (m), 579 (w) cm−1. 1H NMR (600 MHz, CDCl3, TMS): δ 9.66 (s, 1H), 9.09
(s, 1H), 8.12 (s, 1H), 8.01 (s, 1H), 7.76 (s, 2H), 7.65 (s, 1H), 7.49 (s, 3H), 7.07 (s, 1H),
6.94 (s, 1H).
2.5. Synthesis of 4
Similar to TU3, TU4 (0.405 g, 1.5 mmol) and Fe2(CO)9 (1.637 g, 4.5 mmol) gave, using
petroleum ether/CH2Cl2 (1:2, v/v) as eluent, S2Fe3(CO)9 (0.053 g) and 4 (0.223 g, 44%).
Anal. Calcd for C21H14Fe3N4O7S2 (%): C, 37.87; H, 2.12; N, 8.41. Found: C, 37.89; H,
2.14; N, 8.39. IR (KBr): 3321 (m), 2849 (m), 2087 (vs), 2019 (vs), 1988 (s), 1599 (w),
1488 (m), 1297 (w), 1255 (w), 1088 (w), 1029 (w), 757 (m), 697 (m), 666 (w), 593 (w),
1
560 (w), 512 (w) cm−1. H NMR (600 MHz, CDCl3, TMS): δ 9.63 (s, 1H), 9.03 (s, 1H),
8.11 (s, 1H), 7.97 (s, 1H), 7.65 (s, 4H), 7.01–6.89 (d, 3H), 2.43 (s, 3H).
2.6. Synthesis of 5
To a solution of TU5 (0.401 g, 1.56 mmol) in 15 mL of THF was added Fe3(CO)12
(0.786 g, 1.56 mmol). The mixture was stirred at room temperature for 24 h. After the sol-
vent was removed under vacuum, the residue was subjected to TLC separation using
CH2Cl2/petroleum ether (3:20, v/v) as eluent. From the first band, S2Fe3(CO)9 (0.148 g)
was obtained. From the second band, 5 was obtained as a brown solid (0.311 g, 60%).
Anal. Calcd for C20H11Fe3N3O8S2 (%): C, 36.79; H, 1.70; N, 6.44. Found: C, 36.83; H,
1.76; N, 6.40. IR (KBr): 3229 (w), 2058 (vs), 2014 (vs), 1686 (m), 1500 (m), 1331 (w),
1
772 (w) cm−1. H NMR (500 MHz, CDCl3, TMS): δ 13.05 (s, 1H, NH), 9.99 (s, 1H, NH),
8.21–7.08 (m, 9H, ArH). 13C NMR (126 MHz, CDCl3, TMS): δ 235.9, 217.6, 211.2, 207.0,
206.9, 184.3, 165.5, 156.9, 147.6, 137.7, 134.4, 129.6, 119.3, 112.3.
2.7. Synthesis of 6
Similar to TU5, TU6 (0.258 g, 1.0 mmol) and Fe3(CO)12 (0.504 g, 1.0 mmol) afforded,
after TLC separation using CH2Cl2/petroleum ether (1:2, v/v) as eluent, S2Fe3(CO)9
(0.083 g), 6 as a brown-black solid (0.082 g, 26%), and C22H10Fe3N4O11 as a green solid
(0.014 g, 2%) in decreasing order of Rf values. Anal. Calcd for C22H10Fe3N4O11 (%): C,
39.21; H, 1.50; N, 8.31. Found: C, 39.34; H, 1.56; N, 8.32. IR (KBr): 3199 (w), 2072 (vs),
2016 (vs), 1982 (vs), 1954 (vs), 1854 (m), 1673 (m), 1524 (m), 1349 (m), 768 (w), 705
(w), 668 (w). Anal. Calcd for C19H10Fe3N4O8S2 (%): C, 34.90; H, 1.54; N, 8.57. Found: C,
34.96; H, 1.58; N, 8.56. IR (KBr): 3219 (w), 2058 (vs), 2018 (vs), 1974 (vs), 1944 (vs),
1
1687 (w), 1492 (m), 1251 (w), 803 (w), 704 (w), 582 (w) cm−1. H NMR (300 MHz,
CD3COCD3, TMS): δ 13.26 (s, 1H, NH), 10.57 (s, 1H, NH), 8.74–7.36 (m, 8H, ArH).
2.8. Synthesis of 7
A mixture of TU7 (0.306 g, 2.0 mmol) and Fe3(CO)12 (1.007 g, 2.0 mmol) in 15 mL THF
was stirred at room temperature for 24 h. After the solvent was removed under vacuum, the
residue was subjected to TLC separation using ethyl acetate/petroleum ether (1:2, v/v) as

Fe/S and Fe/Se clusters with diaminocarbenes
3857
eluent. From the first band, S2Fe3(CO)9 (0.080 g) was obtained. From the second band, 7
was obtained as a brown solid (0.110 g, 10%). Anal. Calcd for C13H7Fe3N3O7S2 (%): C,
28.45; H, 1.29; N, 7.66. Found: C, 28.42; H, 1.31; N, 7.68. IR (KBr): 3415 (w), 3294 (w),
2921 (m), 2852 (w), 2053 (vs), 2014 (vs), 1976 (vs), 1930 (vs), 1695 (w), 1620 (w), 1481
1
(w), 1449 (w), 1343 (w), 767 (w), 717 (w) cm−1. H NMR (300 MHz, CD3COCD3, TMS):
δ 10.54 (s, 1H, NH), 8.01–6.98 (m, 4H, ArH), 2.80 (s, 2H, NH2). 13C NMR (75 MHz,
CD3COCD3, TMS): δ 213.0, 209.2, 147.5, 139.4, 118.4, 111.1.
2.9. Synthesis of 8
Similar to TU7, TU8 (0.344 g, 1.5 mmol) and Fe3(CO)12 (0.756 g, 1.5 mmol) afforded,
using CH2Cl2/petroleum ether (1:4, v/v) as eluent, S2Fe3(CO)9 (0.099 g) and 8 as a brown
solid (0.273 g, 58%). Anal. Calcd for C19H11Fe3N3O7S2 (%): C, 36.51; H, 1.77; N, 6.72.
Found: C, 36.62; H, 1.79; N, 6.75. IR (KBr): 3033 (w), 2055 (vs), 2007 (vs), 1671 (w),
1
1599 (m), 1532 (m), 1478 (m), 772 (w), 699 (w) cm−1. H NMR (500 MHz, CD3COCD3,
TMS): δ 10.37 (s, 1H, NH), 9.27 (s, 1H, NH), 8.11–7.04 (m, 9H, ArH). 13C NMR
(126 MHz, CD3COCD3, TMS): δ 213.1, 209.2, 147.6, 139.4, 131.0, 129.0, 127.0, 119.0,
112.1.
2.10. Synthesis of 9
Analogous to TU8, TU9 (0.368 g, 1.6 mmol) and Fe3(CO)12 (0.806 g, 1.6 mmol) in 15 mL
of THF gave, after TLC separation using CH2Cl2/petroleum ether (1:1, v/v) as eluent,
S2Fe3(CO)9 (0.089 g) and 9 as a brown solid (0.152 g, 30%). Anal. Calcd for C18H10Fe3-
N4O7S2 (%): C, 34.54; H, 1.61; N, 8.95. Found: C, 34.51; H, 1.63; N, 8.97. IR (KBr):
3026 (w), 2055 (vs), 2013 (vs), 1983 (vs), 1952 (vs), 1920 (m), 1525 (m), 801 (w), 771
1
(w), 694 (w) cm−1. H NMR (300 MHz, CD3COCD3, TMS): δ 10.47 (s, 1H, NH), 9.49 (s,
1H, NH), 8.56–7.15 (m, 8H, ArH). 13C NMR (75 MHz, CD3COCD3, TMS): δ 213.0,
206.1, 159.3, 157.3, 131.0, 129.2, 126.9, 115.3, 115.2.
2.11. Synthesis of 10
Similar to TU9, TU10 (0.243 g, 1.0 mmol) and Fe3(CO)12 (0.504 g, 1.0 mmol) afforded,
after TLC separation using CH2Cl2/petroleum ether (3:10, v/v) as eluent, S2Fe3(CO)9
(0.068 g) and 10 as a brown solid (0.064 g, 20%). Anal. Calcd for C20H13Fe3N3O7S2 (%):
C, 37.59; H, 2.05; N, 6.58. Found: C, 37.45; H, 2.08; N, 6.67. IR (KBr): 3028 (w), 2059
1
(vs), 2016 (vs), 1938 (s), 1909 (m), 1526 (m), 582 (m) cm−1. H NMR (300 MHz, CDCl3,
TMS): δ 8.12–7.40 (m, 8H, ArH), 6.90 (s, 1H, NH), 6.80 (s, 1H, NH), 2.33 (s, 3H, CH3).
13C NMR (75 MHz, CDCl3, TMS): δ 224.9, 220.0, 212.1, 207.4, 157.0, 147.8, 137.3,
132.3, 127.6, 127.0, 117.8, 109.8, 17.6.
2.12. Synthesis of 11
To a solution of TU11 (0.259 g, 1.0 mmol) in 15 mL of THF was added Fe3(CO)12
(0.756 g, 1.5 mmol). The mixture was stirred at room temperature for 24 h. After the
solvent was removed in vacuo, the residue was subjected to TLC separation using CH2Cl2/
petroleum ether (1:1, v/v) as eluent. From the first band, S2Fe3(CO)9 (0.068 g) was

3858
Y.-C. Shi et al.
obtained. From the second band, 11 was obtained as a black solid (0.085 g, 27%). Anal.
Calcd for C25H13Fe5N3O13S3 (%): C, 31.98; H, 1.40; N, 4.48. Found: C, 32.05; H, 1.43; N,
4.51. IR (KBr): 3223 (w), 2059 (vs), 2013 (vs), 1906 (m), 1829 (m), 1523 (m), 581 (w)
1
cm−1. H NMR (300 MHz, CD3COCD3, TMS): δ 7.89 (s, 1H, NH), 7.55–7.04 (m, 8H,
ArH), 5.62 (s, 1H, NH), 3.95 (s, 3H, CH3). 13C NMR (75 MHz, CD3COCD3, TMS):
δ 221.4, 219.3, 146.8, 139.7, 130.2, 127.1, 118.4, 112.8, 111.9, 55.5.
2.13. Synthesis of 12
A mixture of TU12 (0.366 g, 1.5 mmol) and Fe3(CO)12 (1.133 g, 2.25 mmol) in 15 mL of
THF was stirred at 50 °C for 4 h. After removal of the solvent under vacuum, the residue
was subjected to TLC separation using CH2Cl2 as eluent. From the first band, S2Fe3(CO)9
(0.055 g) was obtained. From the second band, 12 was obtained as a brown solid (0.108 g,
24%). Anal. Calcd for C24H12Fe5N4O12S3 (%): C, 31.20; H, 1.31; N, 6.06. Found: C,
31.23; H, 1.34; N, 6.02. IR (KBr): 3336 (w), 2070 (m), 2045 (vs), 2023 (vs), 1986 (vs),
1
1820 (m), 1615 (w), 1525 (w), 1483 (w), 775 (w), 607 (w), 572 (w) cm−1. H NMR (600
MHz, CDCl3, TMS): δ 8.56 (s, 1H, NH), 7.72 (s, 1H, NH), 7.57–6.90 (m, 8H, ArH), 4.06
(s, 2H, NH2).
2.14. Synthesis of 13
Similar to TU12, TU13 (0.366 g, 1.5 mmol) and Fe3(CO)12 (1.133 g, 2.25 mmol) afforded,
using CH2Cl2 as eluent, S2Fe3(CO)9 (0.049 g) and 13 as a brown solid (0.097 g, 21%).
Anal. Calcd for C24H12Fe5N4O12S3 (%): C, 31.20; H, 1.31; N, 6.06. Found: C, 31.25; H,
1.28; N, 6.08. IR (KBr): 3347 (w), 2069 (m), 2042 (vs), 2019 (vs), 1982 (vs), 1830 (m),
1529 (m), 607 (m) cm−1. 1H NMR (600 MHz, CDCl3, TMS): δ 8.68 (s, 1H, NH),
7.90–6.78 (m, 8H, ArH), 4.48 (s, 1H, NH), 2.72 (s, 2H, NH2).
2.15. Synthesis of 14
Analogous to TU11, TU14 (0.230 g, 1.0 mmol) and Fe3(CO)12 (0.756 g, 1.5 mmol) gave,
after TLC separation using CH2Cl2/petroleum ether (1:3, v/v) as eluent, S2Fe3(CO)9
(0.051 g) and 14 as a brown solid (0.082 g, 27%). Anal. Calcd for C23H10Fe5N4O12S3 (%):
C, 30.36; H, 1.11; N, 6.16. Found: C, 30.42; H, 1.17; N, 6.22. IR (KBr): 3344 (w), 2917
(w), 2047 (vs), 2015 (vs), 1926 (m), 1832 (m), 1599 (m), 1516 (m), 1475 (m), 774 (w),
1
606 (w), 570 (w) cm−1. H NMR (600 MHz, CD3COCD3, TMS): δ 14.48 (s, 1H, NH),
9.53 (s, 1H, NH), 8.42–7.15 (m, 8H, ArH).
2.16. Synthesis of 15
Similar to TU14, TU15 (0.309 g, 1.6 mmol) and Fe3(CO)12 (1.209 g, 2.4 mmol) afforded,
after TLC separation using CH2Cl2/petroleum ether (2:1, v/v) as eluent, S2Fe3(CO)9
(0.045 g) and 15 as a brown solid (0.112 g, 24%). Anal. Calcd for C21H11Fe5N3O12S3 (%):
C, 28.90; H, 1.27; N, 4.81. Found: C, 28.94; H, 1.31; N, 4.82. IR (KBr): 3362 (w), 2047
(vs), 1989 (vs), 1839 (m), 1553 (w), 1485 (w), 606 (w), 572 (w) cm−1. 1H NMR
(600 MHz, CDCl3, TMS): δ 10.44 (s, 1H, NH), 8.04 (s, 1H, NH), 7.76–7.03 (m, 4H, ArH),

Fe/S and Fe/Se clusters with diaminocarbenes
3859
5.99–5.90 (m, 1H, CH), 5.30–5.22 (m, 2H, CH2), 4.25–4.23 (m, 2H, CH2). 13C NMR
(151 MHz, CDCl3, TMS): δ 213.0, 147.5, 139.5, 133.6, 118.7, 116.2, 111.5, 55.2, 46.7.
2.17. Synthesis of 16
Solution of SU1 (0.239 g, 1.0 mmol) in 15 mL of THF was cooled to 0 °C, then Fe3(CO)12
(0.756 g, 1.5 mmol) was added. The resulting mixture was stirred in the dark at room
temperature for 24 h. After the solvent was removed in vacuo, the residue was subjected to
TLC separation using CH2Cl2/petroleum ether (1:5, v/v) as eluent. From the first band
was obtained Se2Fe3(CO)9 (0.043 g) which was identified by comparison of its melting
point and IR spectrum with those of an authentic sample. From the second band,
C44H22Fe8N4O24Se3 was obtained as a brown solid (0.084 g, 10%). When the eluent was
changed to CH2Cl2/petroleum ether (1:2, v/v), 16 was obtained as a black solid (0.019 g,
3%). Anal. Calcd for C44H22Fe8N4O24Se3 (%): C, 31.56; H, 1.32; N, 3.35. Found: C,
31.59; H, 1.37; N, 3.38. IR (KBr): 3321 (w), 2910 (w), 2051 (vs), 1988 (vs), 1523 (w), 610
1
(w) cm−1. H NMR (300 MHz, CD3COCD3, TMS): δ 7.43–7.00 (m, 10H, ArH), 5.91–5.80
(m, 2H, 2CH), 5.18–5.16 (m, 4H, 2CH2), 3.95 (s, br, 2H, 2NH), 2.97–2.61 (m, 4H, 2CH2).
Anal. Calcd for C18H12Fe3N2O8Se (%): C, 34.27; H, 1.92; N, 4.44. Found: C, 34.19; H,
1.88; N, 4.41. IR (KBr): 3328 (w), 2862 (w), 2052 (s), 1999 (vs), 1955 (vs), 1956 (vs),
1
1856 (m), 1548 (m), 575 (w), 535 (w) cm−1. H NMR (400 MHz, CD3COCD3, TMS):
δ 7.59 (s, 1H, NH), 7.46–7.00 (m, 5H, ArH), 5.12 (s, 1H, NH), 4.31–4.28 (m, 2H, CH2),
4.11–4.07 (m, 1H, CH), 3.62–2.05 (m, 2H, CH2). 13C NMR (100 MHz, CD3COCD3,
TMS): δ 213.4, 209.3, 152.1, 131.4, 128.3, 126.2, 114.8, 44.2.
2.18. Synthesis of 17
Similar to SU1, SU2 (0.277 g, 1.0 mmol) and Fe3(CO)12 (0.504 g, 1.0 mmol) provided,
after TLC separation using CH2Cl2/petroleum ether (2:3, v/v) as eluent, Se2Fe3(CO)9
(0.046 g) and 17 as a brown solid (0.085 g, 24%). Anal. Calcd for C18H10Fe3N4O7Se2 (%):
C, 30.04; H, 1.40; N, 7.78. Found: C, 30.11; H, 1.43; N, 7.69. IR (KBr): 3331 (w), 2051
(vs), 2013 (vs), 1966 (vs), 1919 (vs), 1588 (w), 1520 (m), 1366 (w), 802 (w), 671 (w), 607
1
(w) cm−1. H NMR (300 MHz, CD3COCD3, TMS): δ 10.46 (s, 1H, NH), 9.56 (s, 1H, NH),
8.56–7.40 (m, 8H, ArH). 13C NMR (75 MHz, CD3COCD3, TMS): δ 214.5, 210.5, 159.2,
157.6, 131.0, 129.2, 126.9, 116.3.
2.19. Synthesis of 18
Analogous to SU2, SU3 (0.306 g, 1.0 mmol) and Fe3(CO)12 (0.504 g, 1.0 mmol) afforded,
after TLC separation using CH2Cl2/petroleum ether (1:1, v/v) as eluent, Se2Fe3(CO)9
(0.055 g) and 18 as a brown solid (0.152 g, 40%). Anal. Calcd for C20H13Fe3N3O8Se2 (%):
C, 32.08; H, 1.75; N, 5.61. Found: C, 32.16; H, 1.82; N, 5.49. IR (KBr): 3363 (w), 2838
(w), 2045 (vs), 2003 (vs), 1957 (vs), 1926 (vs), 1521 (vs), 1261 (w), 1151 (w), 759 (w),
1
604 (w), 585 (w) cm−1. H NMR (300 MHz, CD3COCD3, TMS): δ 8.98 (s, 1H, NH), 8.37
(s, 1H, NH), 8.11–7.03 (m, 8H, ArH), 3.90 (s, 3H, CH3). 13C NMR (75 MHz, CD3COCD3,
TMS): δ 213.6, 209.7, 146.9, 138.3, 129.7, 127.6, 117.9, 112.7, 110.9, 55.4.

3860
Y.-C. Shi et al.
2.20. X-ray determinations of 1–18
Single crystals of C22H10Fe3N4O11, C44H22Fe8N4O24Se3, and 1–18 suitable for X-ray
diffraction analyses were grown by slow evaporation of the CH2Cl2-petroleum ether
solutions at 0–4 °C. For each cluster, a selected single crystal was mounted on a Bruker
APEX II CCD diffractometer which used graphite-monochromated Mo-Kα radiation
(λ = 0.71073 Å) at 296 K. The structures were solved by direct methods using SIR-2011
[48] and refined by full-matrix least-squares based on F2 with anisotropic thermal
parameters for all non-hydrogen atoms using SHELXTL [49] and WinGX [50]. Anisotro-
pic displacement parameters were refined for all non-hydrogen atoms. All N-bound H
atoms were determined from Fourier difference maps and refined independently in
isotropic approximation except for 12 and 13, whereas all C-bound H atoms were placed
at geometrically idealized positions and subsequently treated as riding with C–H = 0.93
(aromatic, olefinic), 0.98 (CH), 0.97 (CH2), 0.96 (CH3) Å and Uiso(H) values
of 1.2 Ueq(C, N) and 1.5 Ueq(CH3). All interactions and close contacts were analyzed
with PLATON [51] and MERCURY [52]. For 5, poor data does not afford accurate
geometric parameters (crystal data for 5: C20H11Fe3N3O8S2, Fw = 652.99, monoclinic,
space group P 21/c, a = 16.8042(12), b = 12.757(2), c = 24.3897(12), β = 96.7997(15)°,
Table 1. Crystal data and structure refinements for 1–4 and 6.
1
2
3
4
6
Formula
Fw
Cryst system
Space group
a (Å)
b (Å)
c (Å)
α (°)
β (°)
C18H12Fe3N2O8S C18H13Fe3N3O8S C20H12Fe3N4O7S2 C21H14Fe3N4O7S2 C19H10Fe3N4O8S2
583.91
Monoclinic
P 21/c
598.92
652.01
Monoclinic
P 21/c
666.03
Monoclinic
I 2/a
653.98
Triclinic
Triclinic
ꢀ
ꢀ
P 1
P 1
10.0221(9)
18.0078(16)
14.9644(2)
90.00
126.989(4)
90.00
8.2495(18)
9.675(2)
14.7681(13)
84.226(2)
74.857(3)
84.899(3)
1129.6(4)
2
25.552(3)
11.4537(15)
17.622(2)
90.00
104.655(2)
90.00
17.4507(19)
11.5081(16)
26.531(2)
90.00
100.835(3)
90.00
9.7877(19)
10.1430(11)
13.3690(13)
91.463(2)
106.746(3)
108.144(2)
1198.0(3)
2
γ (°)
V (Å3)
Z
2157.2(3)
4
4989.6(10)
8
5233.1(10)
8
Dc (g/cm−3
μ/mm−1
)
1.798
1.761
1.736
1.691
1.813
2.135
2.042
1.936
1.848
2.020
F(0 0 0)
1168
600
2608
2672
652
Index ranges
−12 ≤ h ≤ 12
−23 ≤ k ≤ 23
−18 ≤ l ≤ 19
18,486
−10 ≤ h ≤ 10
−12 ≤ k ≤ 12
−19 ≤ l ≤ 19
9923
−33 ≤ h ≤ 32
−14 ≤ k ≤ 14
−22 ≤ l ≤ 22
42,675
−22 ≤ h ≤ 22
−13 ≤ k ≤ 14
−34 ≤ l ≤ 34
21,996
−11 ≤ h ≤ 12
−13 ≤ k ≤ 12
−17 ≤ l ≤ 17
10,637
Measured
data
Unique data
Data
4921
4167
5066
2329
11,335
6341
6078
4233
5400
2916
[I > 2σ(I)]
Rint
0.053
27.5
297
0.060
27.5
304
0.085
27.5
664
0.065
27.7
335
0.051
27.6
331
θ
max (°)
Refined
parameters
R1
wR2
0.0313
0.0816
0.0507
0.1235
0.0474
0.1195
0.0541
0.1652
0.0453
0.0949
GOF
Peak/hole
1.07
0.36/−0.67
0.91
0.50/−0.36
0.98
0.71/−0.45
1.06
1.07/−1.13
0.92
0.39/−0.37

Fe/S and Fe/Se clusters with diaminocarbenes
3861

3862
Y.-C. Shi et al.

Fe/S and Fe/Se clusters with diaminocarbenes
3863
Z = 8, V = 5191.7(9) Å3; Dc = 1.671 gcm−3; μ(Mo-Kα) = 1.863 mm−1; λ = 0.71073 Å;
T = 296 K). For 8 and 11, a CH2Cl2 molecule is disordered over two positions (0.72/
0.28, 8; 0.55/0.45, 11). Additionally, the CH3OC6H4 group of 11 is also disordered over
two positions (0.52/0.48). As for 14, the residual electron density at (0.1672, 0.9206,
0.2831) is 1.18e/Å3 and 1.36 Å away from S1, which does not mean the presence of
H2O. For 18, a water molecule is disordered over two positions (0.51/0.49). Plots of
clusters are drawn using PLATON [51]. Details of crystal data, data collections, and
structure refinements are listed in tables 1–3.
3. Results and discussion
3.1. Syntheses and characterizations of clusters
The reaction of C3H5NHC(=S)NHPh with Fe3(CO)12 in a molar ratio of 1:1 affords (μ3-S)
Fe3(CO)7(μ-CO)(κ3C,C,C-C3H5NHCNHPh) (1). Similarly, C3H5NHC(=S)NH(4-H2NC6H4)
reacts with Fe3(CO)12 to produce (μ3-S)Fe3(CO)7(μ-CO)(κ3C,C,C-C3H5NHCNH(4-
H2NC6H4)) (2) (scheme 1). Unlike the above thioureas, the reaction of (2-C5H4N)NHC(=S)
NHN=HCPh with Fe3(CO)12 or Fe2(CO)9 in a molar ratio of 1:3 gives (μ3-S)2Fe3(CO)7(κ2N,
C-(2-C5H4N)NHCNHN=HCPh) (3). The reaction of (2-C5H4N)NHC(=S)NHN=HC(4-
CH3C6H4) with Fe2(CO)9 proceeds in a similar fashion to result in the formation of
(μ3-S)2Fe3(CO)7(κ2N,C-(2-C5H4N)NHCNHN=HC(4-CH3C6H4)) (4). Reaction of (2-C5H4N)
NHC(=S)NHC(=O)Ph with Fe3(CO)12 forms (μ3-S)2Fe3(CO)7(κ2N,C-(2-C5H4N)NHCNHC
R
HN
NH
OC
C
Fe
C3H5NHC(=S)NHR
CO
S
Fe(CO)3
(OC)3Fe
(1-2)
R
Fe3(CO)12
HN
NH
N
(2-C5H4N)NHC(=S)NHR
OC
C
Fe
S
S
(OC)3Fe
Fe(CO)3
(3-4)
Scheme 1. Syntheses of 1–4 (1, R, C6H5; 2, R, 4-H2NC6H4; 3, R, N=CHC6H5; 4, R, N=CH(4-CH3C6H4)).

3864
Y.-C. Shi et al.
(=O)Ph) (5). Interestingly, (2-C4H3N2)NHC(=S)NHC(=O)Ph offers (μ3-S)2Fe3(CO)7(κ2N,C-
(2-C4H3N2)NHCNHC(=O)Ph) (6) as well as Fe3(CO)8(μ-CO)2(κ2N,C-(2-C4H3N2)NHCNHC
(=O)Ph) (scheme 2). In particular, the reaction of (2-C5H4N)NHC(=S)NH2 with Fe3(CO)12
provides (μ3-S)2Fe3(CO)7(κ2N,C-(2-C5H4N)NHCNH2) (7) (scheme 3), which can also be
almost quantitatively generated from the reaction of 5 with KOH in THF. In contrast, the
reactions of GNHC(=S)NHPh with Fe3(CO)12 have been investigated and clusters of
(μ3-S)2Fe3(CO)7(κ2N,C-GNHCNHPh) (8, G = 2-C5H4N; 9, G = 2-C4H3N2) are obtained.
Similarly, the reaction of (2-C5H4N)NHC(=S)NH(2-CH3C6H4) with Fe3(CO)12 forms
(μ3-S)2Fe3(CO)7(κ2N,C-(2-C5H4N)NHCNH(2-CH3C6H4)) (10). Seemingly, the thioureas
with N-heterocycles are prone to produce the S2Fe3-type clusters. However, to our surprise,
the reaction of (2-C5H4N)NHC(=S)NH(2-CH3OC6H4) with Fe3(CO)12 in a molar ratio of
1:1.5 generates an unprecedented S3Fe5-type cluster, (μ3-S)2(μ4-S)Fe5(CO)10(μ-CO)2(κ2N,C-
(2-C5H4N)NHCNH(2-CH3OC6H4)) (11) (scheme 4). Reactions of (2-C5H4N)NHC(=S)NHR
with Fe3(CO)12 also yield (μ3-S)2(μ4-S)Fe5(CO)10(μ-CO)2(κ2N,C-(2-C5H4N)NHCNHR) (12,
R = 2-H2NC6H4; 13, R = 4-H2NC6H4; 14, R = 2-C5H4N). More interestingly, the reaction of
(2-C5H4N)NHC(=S)NHC3H5 with Fe3(CO)12 gives (μ3-S)2(μ4-S)Fe5(CO)10(μ-CO)2(κ2N,C-
(2-C5H4N)NHCNHC3H5) (15). In order to compare the reactivity toward iron carbonyls
between thioureas and selenoureas, reactions of three selenoureas with Fe3(CO)12 have
been carried out. The reaction of C3H5NHC(=Se)NHPh with Fe3(CO)12 affords
(μ3-Se)Fe3(CO)7(μ-CO)(κ3C,C,C-C3H5NHCNHPh) (16) as well as [(κ2N,C-PhN=CNHC3
H5)Fe2(CO)6(μ4-Se)Fe2(CO)6]2(μ4-Se) (scheme 5). Like (2-C4H3N2)NHC(=S)NHPh,
(2-C4H3N2)NHC(=Se)NHPh reacts with Fe3(CO)12 to form (μ3-Se)2Fe3(CO)7(κ2N,C-(2-
C4H3N2)NHCNHPh) (17) and (2-C5H4N)NHC(=Se)NHPh provides (μ3-Se)2Fe3(CO)7(κ2N,
C-(2-C5H4N)NHCNHPh). In sharp contrast with (2-C5H4N)NHC(=S)NH(2-CH3OC6H4),
R
HN
NH
OC
S
C
Fe
N
(2-C5H4N)NHC(=S)NHR
S
(OC)3Fe
Fe(CO)3
(5)
Fe3(CO)12
R
HN
(2-C4H3N2)NHC(=S)NHR
NH
N
OC
S
C
Fe
N
S
(OC)3Fe
Fe(CO)3
(6)
Scheme 2. Syntheses of 5 and 6 (5, R, COPh; 6, R, COPh).

Fe/S and Fe/Se clusters with diaminocarbenes
3865
R
HN
NH
OC
S
C
Fe
N
(2-C5H4N)NHC(=S)NHR
S
(OC)3Fe
Fe(CO)3
(7, 8, 10)
Fe3(CO)12
R
HN
C
(2-C4H3N2)NHC(=S)NHR
NH
OC
N
Fe
N
S
S
(OC)3Fe
Fe(CO)3
(9)
Scheme 3. Syntheses of 7–10 (7, R, H; 8, R, C6H5; 9, R, C6H5; 10, R, 2-CH3C6H4).
R
HN
NH
OC
S
C
Fe
N
(2-C5H4N)NHC(=S)NHR
Fe3(CO)12
S
CO
S
Fe(CO)3
Fe
(OC)3Fe
OC
Fe(CO)3
(11-15)
Scheme 4. Syntheses of 11–15 (11, R, 2-CH3OC6H4; 12, R, 2-H2NC6H4; 13, R, 4-H2NC6H4; 14, R, 2-C5H4N;
15, R, C3H5).
(2-C5H4N)NHC(=Se)NH(2-CH3OC6H4) yields (μ3-Se)2Fe3(CO)7(κ2N,C-(2-C5H4N)NHCNH
(2-CH3OC6H4)) (18). Although mechanistic details have not been explored, we propose a
possible mechanism to shed light on formation of these new Fe/S clusters with chelating
carbene ligands [53] (chart 1): thiourea GNHC(=S)NHR (G = coordination group: 2-C5H4N,
2-C4H3N2, CH2CH=CH2) reacts with iron carbonyls to produce M1 with loss of CO; M1
undergoes a thermal rearrangement to afford an SFe3-type cluster or via an S transfer leads to
an unstable derivative (M2) of Fe3(CO)12 with a chelating carbene ligand and an S2Fe3-type

3866
Y.-C. Shi et al.
Ph
HN
NH
OC
C
Fe
C3H5NHC(=Se)NHPh
CO
Se
Fe(CO)3
(OC)3Fe
(16)
Ph
HN
NH
N
OC
C
(2-C4H3N2)NHC(=Se)NHPh
Fe
Se
N
Se
Fe3(CO)12
(OC)3Fe
Fe(CO)3
(17)
OMe
NH
HN
OC
C
(2-C5H4N)NHC(=Se)NH(2-CH3OC6H4)
Fe
Se
N
Se
(OC)3Fe
Fe(CO)3
(18)
Scheme 5. Syntheses of 16–18.
cluster, or reacts with Fe3(CO)12 to offer M2 and SFe3(CO)10 (M3) [54]; M3 reacts with the
S2Fe3-type cluster to form an S3Fe5-type cluster with Fe(CO)5 being released, whereas
S2Fe3(CO)9 is generated by self-condensation of M3. The green structurally characterized
M2, Fe3(CO)8(μ-CO)2(κ2N,C-(2-C4H3N2)NHCNHC(=O)Ph), and yellow Fe(CO)5 detected
support these hypotheses. Naturally, the isolation of the above Se3Fe8 cluster hints that
besides possible intermediates (GNHCSeNHR)Fe3(CO)9, (GNHCNHR)Fe3(CO)10, and
SeFe3(CO)10 [55], being similar to M1, M2, and M3 (drawn in chart 1), selenourea GNHC
(=Se)NHR (G = coordination group: 2-C5H4N, 2-C4H3N2, CH2CH=CH2) reacts through
another pathway, via an unstable intermediate (μ-HSe)Fe2(CO)6(κ2C,N-GNHC=NR), to
generate an Se3Fe8 cluster [28(d)].
1
These new clusters have been characterized by FT-IR, H NMR, 13C{1H} NMR, and ele-
mental analyses. In the IR spectra, the NH vibration is at 3026–3366 cm−1. The terminal
carbonyl groups show two to four strong absorptions from 1906 to 2070 cm−1. The

Fe/S and Fe/Se clusters with diaminocarbenes
3867
M2
+
M3
Fe3(CO)12
or Fe2(CO)9
NHR
NHR
HN
HN
G
C
C
G
C-S cleavage
- CO
Fe3(CO)12
S
Fe(CO)
Fe(CO)2
GNHC(=S)NHR
or Fe2(CO)9
CO
S
CO
Fe(CO)3
(OC)3Fe
Fe(CO)3
(OC)3Fe
(M1)
(SFe3 type)
S2Fe3(CO)9
NHR
NHR
HN
NHR
HN
G
HN
C
C
C
G
SFe3(CO)10
(M3)
G
Fe(CO)
Fe(CO)
Fe(CO)
S
CO
CO
S
S
CO
S
Fe(CO)3
S
Fe
(OC)4Fe
(OC)3Fe
Fe(CO)3
Fe(CO)3
(OC)3Fe
CO
(S3Fe5 type)
(M2)
(S2Fe3 type)
Fe(CO)3
Chart 1. Proposed mechanism for Fe/S clusters.
bridging carbonyl group(s) occur(s) at 1820–1863 cm−1 for SFe3, S3Fe5, and SeFe3 clusters
(1, 1862 (m); 2, 1863 (m); 11, 1829 (m); 12, 1820 (m); 13, 1830 (m); 14, 1832 (m); 15,
1839 (m); 16, 1856 (m) cm−1). These data strongly support the seemingly unacceptably
1
long Fe-carbonyl bonds determined by X-ray crystallography (see below). In the H NMR
spectra, the NH group, which was verified by D2O exchange, shows a slightly upfield shift
by comparison with the corresponding thiourea and selenourea. The very low-field signals
for 5 (δ 13.05), 6 (δ 13.26), and 14 (δ 14.48) result from strong classical hydrogen bonds
(N–Hꢀ ꢀ ꢀO, N–Hꢀ ꢀ ꢀO, and N–Hꢀ ꢀ ꢀN). In the 13C NMR spectra, the carbene C is at
[Fe]
C
G
[Fe]
C
G
H
(
R
N
H
N
H
N
H
N
R
)
(I)
(II)
Chart 2. Two conformations of chelating N,Nʹ-diaminocarbenes. Dashed lines indicate hydrogen bonds.

3868
Y.-C. Shi et al.
147–159 ppm. The signals from the CO groups reveal that the five types of SFe3, S2Fe3,
S3Fe5, SeFe3, and Se2Fe3 clusters are all fluxional in solution.
3.2. Molecular structures of clusters
These new clusters including green Fe3(CO)8(μ-CO)2(κ2N,C-(2-C4H3N2)NHCNHC(=O)
Ph) and black [(κ2N,C-PhN=CNHC3H5)Fe2(CO)6(μ4-Se)Fe2(CO)6]2(μ4-Se) (see Supple-
mentary Data) have been structurally determined by X-ray crystallography. However, for
clarity, only molecular structures of 1, 4, 6, 7, 9, 11, 13, 14, 16, and 17 are discussed
below.
Cluster 1 (figure 1) consists of a triangular core of irons with three Fe–Fe bonds capped
by a sulfide ligand, which is 1.5975(6) Å from the triiron plane [54]. The sulfide ligand
symmetrically links three Fe atoms with Fe–S bond lengths averaging 2.197(6) Å, com-
pared to the Fe–S bond length of 2.21(1) Å in Fe3(CO)9(µ3-CO)(µ3-S) [54(a)]. Fe1 has one
terminal carbonyl and chelating carbene ligand, while Fe2 and Fe3 each bear three terminal
carbonyls. The carbonyl on Fe1 is obviously bent toward Fe3 with a 171.7(2)° angle of
Fe1–C1–O1. The Fe3ꢀ ꢀ ꢀC1 distance of 2.765(3) Å suggests an intramolecular contact
between the two atoms [r, covalent radius; R, van der Waals radius; r(Fe) = 1.45, r(C)
= 0.68, r(Fe) + r(C) = 2.13 Å; R(Fe) = 2.14, R(C) = 1.70, R(Fe) + R(C) = 3.84 Å] [51]. The
semibridging carbonyl binds Fe1 and Fe2 [Fe1–C8, 1.841(2) Å; Fe2–C8, 2.231(2) Å;
Fe1–C8–O8, 154.12(18)°; Fe2–C8–O8, 125.25(16)°; Fe1–C8–Fe2, 80.35(8)°] and lies
approximately trans to the carbene C12 [C8–Fe1–C12, 160.49(9)°]. The existence of the
Figure 1. Molecular structure of 1. Selected geometric parameters (Å,°): Fe1–Fe2, 2.6442(4); Fe2–Fe3, 2.5751
(4); Fe1–Fe3, 2.6156(4); Fe1–S1, 2.1915(6); Fe2–S1, 2.1924(6); Fe3–S1, 2.2071(6); Fe1–C8, 1.841(2); Fe2–C8,
2.231(2); Fe1–C9, 2.115(2); Fe1–C10, 2.116(2); C9–C10, 1.394(3); Fe1–C12, 1.9976(19); Fe1–C1–O1, 171.7(2).

Fe/S and Fe/Se clusters with diaminocarbenes
3869
semibridging carbonyl is due to steric congestion from the chelating carbene ligand and
governed by the 18-electron rule. Notably, the Fe–Csemibridging bond of 2.231(2) Å is signifi-
cantly longer than that of Fe3(CO)8(µ-CO)(µ3-S)(PPh2CCiPr) [Fe1–CO, 1.895(5); Fe2–CO,
2.142(6) Å; IR, 1866 (w) cm−1] [54(b)]. Against expectation, the bridged Fe1–Fe2 bond of
2.6442(4) Å is longer than the other two [Fe2–Fe3, 2.5751(4) Å; Fe1–Fe3, 2.6156(4) Å].
For comparison, three Fe–Fe bond lengths of the reported complex are 2.582(1), 2.591(2),
and 2.620(1) Å. The sum of the bond angles about C12 is 360.00(16)° [Fe1–C12–N1,
116.26(15); Fe1–C12–N2, 126.25(15); N1–C12–N2, 117.49(18)°], indicating that the car-
bene C12 is sp2-hybridized. The Fe1–C12 bond length of 1.998(2) Å in 1 is typical of an
Fe–C single bond, falling near the normal range of 2.0–2.2 Å [25(b), 56, 57] and almost
equal to the Fe–Ccarbene bond lengths of 2.007(5) Å in IMFe(CO)4 (IM = 1,3-dimthylimida-
zol-2-ylidene) [58(a)], 1.992(2) Å in IMesFe(CO)4 (IMes = 1,3-dimesitylimidazol-2-yli-
dene) [58(b)], and 1.992(3) Å in CpFe(CO)(Ph2PCH2CH2CH2HNCNnHex2)I, but longer
than the 1.958(3) Å bond observed in CpFe(CO)(tBu2PCH2CH2CH2HNCNHnBu)I [58(c)].
The C12–N1 and C12–N2 bond lengths of 1.322(3) and 1.335(3) Å suggest π-electrons
delocalizing over the N1–C12–N2 group [53(f), 59]. In this case, the carbene C12 functions
only as an n donor. The bond lengths of Fe1–C9 and Fe1–C10 [2.115(2) and 2.116(2) Å]
show that they are single bonds, whereas the C9–C10 bond of 1.394(3) Å is of some double
bond character. Therefore, the allyl group is best described as a κ2C,C mode and the
chelating carbene ligand is a four-electron donor in a κ3C,C,C fashion. The Fe1C9C10
plane is nearly perpendicular to the carbene CN2 plane, forming a dihedral angle of 89.6
(2)°. The carbene CN2 plane makes a dihedral angle of 71.91(11)° with the phenyl plane.
This type of clusters (1 and 2) with chelating carbene ligands, (μ3-S)Fe3(CO)7(μ-CO)L2
(L2 = Ccarbene–Nheterocycle ligand), is unprecedented.
Figure 2. Molecular structure of 4. Selected geometric parameters (Å,°): Fe1–N1, 2.004(3); Fe1–Fe3, 2.6319(8);
Fe2–Fe3, 2.5494(8); Fe1–S1, 2.2025(11); Fe1–S2, 2.2305(9); Fe2–S1, 2.2589(10); Fe2–S2, 2.2538(11); Fe3–S1,
2.2696(11); Fe3–S2, 2.2755(12); Fe1–C13, 1.914(3); Fe1–C1, 1.736(5); Fe1ꢀ ꢀ ꢀC7, 2.763(4); Fe1–Fe3–Fe2, 82.00
(2); Fe3–C7–O7, 174.1(4).

3870
Y.-C. Shi et al.
As shown in figure 2, 4 contains an open triangle of Fe atoms capped by two S atoms
above and below, with an Fe1–Fe3–Fe2 angle of 82.00(2)°. The S2Fe3 core adopts a
distorted square-pyramidal geometry similar to the previously reported cluster
(μ3−S)2Fe3(CO)9 [59]. In (μ3−S)2Fe3(CO)9, each sulfur on the square base triply bridges
the two basal Fe(CO)3 units on the same base and the third Fe(CO)3 group at the apex of
the pyramid, and each of the three Fe atoms obeys the 18-electron rule. Accordingly, 4 may
be viewed as involving formal replacement of the two equatorial carbonyl ligands on one
of the iron centers on the square base in (μ3−S)2Fe3(CO)9 by a four-electron chelating car-
bene, viz. carbene C and pyridine N, with Fe1–C13 = 1.914(3) and Fe1–N1 = 2.004(3) Å.
The carbene ligand leads to small structural effects, namely a slight increase in the triiron
bond angle compared with (μ3-S)2Fe3(CO)9 [81.13(2)°; 2.5903(9) and 2.5946(9) Å], and a
slight increase in the Fe–Fe bond-length difference from 0.0043(9) to 0.0825(8) Å. Addi-
tionally, one of the three carbonyl ligands attached to the apical Fe takes part in a weak
interaction with the carbene-substituted basal Fe from a direction trans to the carbonyl
ligand bound to the basal Fe [Fe1ꢀ ꢀ ꢀC7 = 2.763(4) Å, Fe1–C1ꢀ ꢀ ꢀC7 = 175.26(15)°]. In
agreement with this interaction is a significant deviation of the Fe–C–O bond angle from
linearity, with carbonyl C7 bent toward Fe1 [Fe3–C7–O7 = 174.1(4)°], whereas the others
are 176.5(5)-178.6(5)°. The Fe–S bonds range from 2.2025(11) to 2.2755(12) Å. Unlike 1
and 2, because the CN2 group is coplanar with the pyridine ring, the sum of the bond
angles at carbene C13 is 360.0(3)° and forms a larger conjugated system, thus strengthening
π back-bonding and leading to the short Fe–Ccarbene bonds described above.
Figure 3. Molecular structure of 6. Selected geometric parameters (Å,°): Fe1–N1, 1.985(3); Fe1–Fe3, 2.6240(9);
Fe2–Fe3, 2.5712(10); Fe1–S1, 2.1902(12); Fe2–S1, 2.2401(12); Fe3–S1, 2.2615(13); Fe1–C12, 1.894(4);
Fe1ꢀ ꢀ ꢀC7, 2.778(6); Fe1–Fe3–Fe2, 81.23(3); Fe3–C7–O7, 173.6(4).

Fe/S and Fe/Se clusters with diaminocarbenes
3871
Figure 4. Molecular structure of 7. Selected geometric parameters (Å,°): Fe1–N1, 2.004(2); Fe1–Fe3, 2.6377(7);
Fe2–Fe3, 2.5507(6); Fe1–S1, 2.2044(8); Fe1–S2, 2.2297(8); Fe3–S1, 2.2661(8); Fe1–C13, 1.912(3); Fe1ꢀ ꢀ ꢀC7,
2.780(5); Fe1–Fe3–Fe2, 81.956(18); Fe3–C7–O7, 172.7(3).
Cluster 6 (figure 3) is isoelectronic to 5. The S2Fe3 core shows a distorted
square-pyramidal geometry. The chelating carbene ligand is, via carbene C12 and pyrim-
idine N1, bonded to Fe1 in the equatorial position and is a four-electron donor. Of the
six Fe–S bonds, the Fe2–S2 bond is the longest at 2.2773(13) Å. The Fe1–C12 bond
length of 1.894(4) Å indicates that there exists a high degree of π back-donation from
Fe1 to C12. In accord with this conclusion, the sum of the bond angles of Fe1–C12–N3
115.5(3), Fe1–C12–N4 126.9(3), and N2–C12–N3 117.7(4) is 360.1(3)°. Owing to the
carbene-bound Fe being coplanar with the CN2 group and the C4H3N2 ring, these atoms
form a larger conjugated system, resulting in the very short Fe–Ccarbene bond. One of
three carbonyls attached to the apical Fe has a weak interaction with the carbene-substi-
tuted basal Fe [Fe1ꢀ ꢀ ꢀC7, 2.778(6) Å; C1–Fe1ꢀ ꢀ ꢀC7, 173.9(2)°], causing a bent Fe–C–O
bond angle [Fe3–C7–O7, 173.6(4)°]. The triiron plane with the chelating ligand forms a
dihedral angle of 87.50(11)°; the chelating ligand with the NCOC plane makes a
dihedral angle of 7.5(5)°.
Similar to 6, 7 (figure 4) contains a triangle of Fe atoms capped by two S atoms above
and below with an Fe1–Fe3–Fe2 angle of 81.956(18)°. Two Fe–Fe bond lengths are 2.6377
(7) and 2.5507(6) Å for Fe1–Fe3 and Fe2–Fe3, respectively. The Fe1–N1 bond length is
2.004(2) Å. The Fe1–C13 bond length of 1.912(3) Å is similar to that of 6. The carbene
C13 is sp2-hybridized with an angle sum of 360.0(3)° [Fe1–C13–N2, 114.3(2)°; Fe1–C13–
N3, 129.7(3)°; N2–C13–N3, 116.0(3)°]. Because the carbene-bound Fe is coplanar with the
CN2 group and the C5H4N ring, these atoms form a larger conjugated system. Unlike the

3872
Y.-C. Shi et al.
Figure 5. Molecular structure of 9. Selected geometric parameters (Å,°): Fe1–N1, 2.002(2); Fe1–Fe3, 2.6095(6);
Fe2–Fe3, 2.5448(6); Fe1–S1, 2.2023(8); Fe2–S1, 2.2562(7); Fe3–S1, 2.2752(8); Fe1–C12, 1.915(2); Fe1ꢀ ꢀ ꢀC7,
2.760(3); Fe1–Fe3–Fe2, 82.899(18); Fe3–C7–O7, 173.0(3).
reported NHCs [53], this planar carbene ligand is both a good σ-donor and a good
π-acceptor. The triiron plane with the chelating ligand forms a dihedral angle of 86.71(11)°.
As in 4–6, the Fe3–S bond lengths [Fe3–S1, 2.2661(8) Å; Fe3–S2, 2.2808(8) Å] in 7 are
longer than the others [2.2044(8)–2.2649(8) Å]. One of the three carbonyl ligands con-
nected to the apical Fe3 involves a weak interaction with the carbene-substituted basal Fe1
from a direction trans to the Fe1-bound carbonyl [Fe1ꢀ ꢀ ꢀC7, 2.780(5) Å], resulting in the
bent Fe3–C7–O7 bond angle [172.7(3)°].
As with 8, 9 (figure 5) belongs to the above S2Fe3 type with an angle of Fe1–Fe3–Fe2
being 82.899(18)°. The Fe1–C12 bond length of 1.915(2) Å is identical to that of 8 [1.915
(3) Å]. The two C12–N bond lengths [C12–N3, 1.357(3); C12–N4, 1.326(3) Å] and the
sum of the angles around C12 [Fe1–C12–N3, 113.87(18)°; Fe1–C12–N4, 129.5(2)°;
N3–C13–N4, 116.6(2)°; 360.0(2)°] indicate that the carbene C12 adopts sp2 hybridization.
With the carbene-bound Fe being coplanar with the CN2 group and the C4H3N2 ring, these
atoms form a larger conjugated system. The triiron plane with the chelating ligand forms a
dihedral angle of 78.79(7)°, clearly smaller than the angle of 89.74(7)° in 8. The chelating
ligand forms a dihedral angle of 57.83(13)° with the phenyl ring. As in 8, one of the three
carbonyl ligands linked to the apical Fe3 interacts weakly with the carbene-substituted basal
Fe1 [Fe1ꢀ ꢀ ꢀC7, 2.760(3) Å; C1–Fe1ꢀ ꢀ ꢀC7, 171.51(12)°; Fe3–C7–O7, 173.0(3)°].
Although complexes of types (μ3-S)2Fe3(CO)7L2 (L = P ligand) and (μ3-S)2Fe3(CO)8L
(L = carbene ligand) are known, clusters with equatorial carbene ligands are extremely rare:
(μ3-S)2Fe3(CO)8L (L = C3Ph2 [59(d)], Fe–Ccarbene, 1.901(7) Å; L = C3H2S2 (dithiocarbene)
[59(e)], Fe–Ccarbene, 1.948(3) Å; L = C10H10N2S2 (aminothiocarbene) [59(f)], Fe–Ccarbene
,

Fe/S and Fe/Se clusters with diaminocarbenes
3873
Figure 6. Molecular structure of 11. Selected geometric parameters (Å,°): Fe1–Fe3, 2.7780(10); Fe2–Fe3, 2.5773
(10); Fe3–Fe4, 2.6075(10); Fe3–Fe5, 2.5992(10); Fe4–Fe5, 2.6098(13); Fe1–S1, 2.2175(15); Fe1–S2, 2.2663(14);
Fe1–S3, 2.5808(15); Fe1–N1, 1.997(4); Fe1–C18, 1.927(5); Fe1–Fe3–Fe2, 78.58(3); Fe3–C11–Fe4, 74.7(2);
Fe3–C12–Fe5, 74.7(2); C1–Fe1–S3, 176.6(2).
1.959(4) Å). This type of clusters with chelating carbene ligands 3–10, (μ3-S)2Fe3(CO)7L2
(L2 = Ccarbene–Nheterocycle chelating ligand), is unprecedented.
Cluster 11 (figure 6) consists of an open triiron and a closed triiron framework sharing
a vertex [60]. The two triangles are really vertical, with a dihedral angle of 89.48(5)°
while a value in [(PPh3)2N]2[Fe5(CO)14(µ3-S)2] is 55.08(3)° [60(b)]. The open triiron
core is capped by two S atoms above and below with an triiron angle of 78.58(3)°,
smaller than that observed in (μ3-S)2Fe3(CO)9 of [81.13(2)°] [59(a)]. The S2Fe3 subcore
in 11 shows a distorted square-pyramidal geometry similar to that in (μ3-S)2Fe3(CO)9.
The chelating carbene ligand as a four-electron donor via the carbene C18 and pyridine
N1 is equatorially coordinated to the basal Fe1 with Fe1–C18 = 1.927(5) Å and Fe1–
N1 = 1.997(4) Å. As in 3–10, carbene C18 is sp2-hybridized [Fe1–C18–N2, 113.6(4)°;
Fe1–C18–N3, 129.1(4)°; N2–C18–N3, 117.3(5)°; 360.0(4)°]. With the carbene-bound Fe
being coplanar with the CN2 group and the C5H4N ring, these atoms form a larger
conjugated system. The chelating ligand is almost perpendicular to the Fe1–Fe3–Fe2
plane, forming a dihedral angle of 87.20(14)°. The closed triiron core is capped by one
S atom. The edge Fe atoms each have three terminal carbonyl groups. Two semibridging
carbonyls on the central Fe3 bind the edge Fe4 and Fe5 [Fe3–C11, 1.804(6); Fe4–C11,
2.418(6); Fe3–C12, 1.797(6); Fe5–C12, 2.410(5) Å]. In particular, the Fe–Csemibridging
bonds of 2.418(6) and 2.410(5) Å are beyond the scope of the Fe–C single bonds [2.0–
2.2 Å] and remarkably longer than those of 1 and 2; this is strongly supported by the

3874
Y.-C. Shi et al.
Figure 7. Molecular structure of 13. Selected geometric parameters (Å,°): Fe1–Fe3, 2.7737(5); Fe2–Fe3, 2.5810
(5); Fe3–Fe4, 2.6047(5); Fe3–Fe5, 2.6111(5); Fe4–Fe5, 2.5940(6); Fe1–S1, 2.2141(8); Fe2–S1, 2.2486(8); Fe1–S3,
2.6150(7); Fe1–N1, 2.004(2); Fe1–C18, 1.912(3); Fe3–C11–Fe4, 74.89(10); Fe3–C12–Fe5, 74.26(10); C1–Fe1–S3,
175.31(9).
FT-IR data for 11. For the reported diiron complex, C14H7NFe2O6, the following related
values are listed for comparison: IR, 1881 cm−1; Fe–Cbridging, 1.798(5), 2.426(5) Å;
Fe–C–O, 125.8(4)°, 163.5(4)° [57(b)]. Among the five Fe–Fe bonds, the Fe1–Fe3 bond
of 2.7780(10) Å is considerably longer than the others, approaching the high limit of the
Fe–Fe single bonds [2.43–2.88] [25(b), 56, 57]. The distance between Fe1 and S3 is
2.5808(15) Å, beyond the normal scope of the Fe–S bonds [2.18–2.37 Å] [3], but closer
to the sum of the covalent radii for Fe and S [r, covalent radius; R, van der Waals
radius; r(Fe) = 1.45, r(S) = 1.04, r(Fe) + r(S) = 2.49 Å; R(Fe) = 2.14, R(S) = 1.80, R
(Fe) + R(S) = 3.94 Å] [51], thereby, the interaction between Fe1 and S3 may be viewed
as a weak bond with a C1–Fe1–S3 angle of 176.6(2)° [61].
Cluster 13 (figure 7) also consists of a bent triiron and a closed triiron framework sharing
a vertex. The two triangles are not coplanar, the dihedral angle being 88.48(2)°. The open
triiron core is capped by two S atoms above and below with an Fe1–Fe3–Fe2 angle of
78.671(15)°. The S2Fe3 subcore in 13 displays a distorted square-pyramidal geometry. The
chelating carbene ligand, through C18 and pyridine N1, is equatorially coordinated to the
basal Fe1 with Fe1–C18 = 1.912(3) Å and Fe1–N1 = 2.004(2) Å. The angle sum of C18
[Fe1–C18–N2, 114.05(18)°; Fe1–C18–N3, 129.0(2)°; N2–C18–N3, 116.9(2)°] is 360.0(2)°,
showing that C18 is sp2-hybridized. The three irons Fe1–Fe3–Fe2 with the chelating ligand
forms a dihedral angle of 85.89(7)°, the C6H4 plane with the chelating ligand makes a dihe-
dral angle of 66.38(13)°, smaller than the 79.5(4)° angle observed in 12. The closed triiron

Fe/S and Fe/Se clusters with diaminocarbenes
3875
core is capped by one S which is weakly bound to the basal Fe1 with the Fe1–S3 separation
of 2.6150(7) Å and C1–Fe1–S3 angle of 175.31(9)°. The edge Fe atoms each have three
terminal carbonyl groups. Two semibridging carbonyl groups on the central Fe3 bind the
edge Fe4 and Fe5, respectively [Fe3–C11, 1.812(3); Fe4–C11, 2.402(3); Fe3–C12, 1.804
(3); Fe5–C12, 2.440(3) Å]. The presence of long Fe–COsemibridging bonds is supported by
the FT-IR data of 13.
As shown in figure 8, 14 belongs to the above S3Fe5 type with five Fe–Fe bonds. The
two triangles are not coplanar, their dihedral angle being 87.92(3)°. The open triiron core is
capped by two S atoms above and below with a triiron angle of 78.16(2)°. As mentioned
above, the S2Fe3 subcore in 14 has a distorted square-pyramidal geometry. The chelating
carbene is coordinated equatorially to the basal Fe1 with Fe1–C18 = 1.912(4) and Fe1–
N1 = 2.005(3) Å. The two C18–N bond lengths are 1.344(5) and 1.338(5) Å [C18–N2 and
C18–N3, respectively]. The angle sum [359.9(3)°] of C18 [Fe1–C18–N2, 114.4(3)°; Fe1–
C18–N3, 126.8(3)°; N2–C18–N3, 118.7(3)°] is indicative of sp2-hybridized C. Due to the
Fe–CN2 unit being coplanar with the C5H4N ring, these atoms form a larger conjugated sys-
tem, leading to the short Fe–Ccarbene bond. The chelating ligand is vertical with the open tri-
iron atoms, with a dihedral angle of 89.63(11)°, the uncoordinated C5H4N ring makes a
dihedral angle of 2.6(5)° with the chelating ligand. The closed triiron core is capped by one
S which is weakly linked to the basal Fe1 with an Fe1–S3 separation of 2.5762(10) Å and
a C1–Fe1–S3 angle of 174.82(13)°. The edge Fe atoms each have three terminal carbonyl
Figure 8. Molecular structure of 14. Selected geometric parameters (Å,°): Fe1–Fe3, 2.7844(6); Fe2–Fe3, 2.5949
(7); Fe3–Fe4, 2.6199(7); Fe3–Fe5, 2.6121(8); Fe4–Fe5, 2.5916(7); Fe1–S1, 2.2113(9); Fe1–S2, 2.2767(9); Fe1–S3,
2.5762(10); Fe1–N1, 2.005(3); Fe1–C18, 1.912(4); Fe1–Fe3–Fe2, 78.16(2); Fe3–C11–Fe4, 73.75(12);
Fe3–C12–Fe5, 73.88(13); C1–Fe1–S3, 174.82(13).

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Y.-C. Shi et al.
Figure 9. Molecular structure of 16. Selected geometric parameters (Å,°): Fe1–Fe2, 2.6714(5); Fe2–Fe3, 2.6015
(6); Fe1–Fe3, 2.6391(6); Fe1–Se1, 2.3104(5); Fe2–Se1, 2.3109(5); Fe3–Se1, 2.3321(5); Fe1–C8, 1.844(3); Fe2–
C8, 2.217(3); Fe1–C9, 2.113(3); Fe1–C10, 2.121(3); C9–C10, 1.386(4); Fe1–C12, 1.994(2); Fe1–C8–Fe2, 81.70
(10); Fe1–C1–O1, 170.9(3).
Figure 10. Molecular structure of 17. Selected geometric parameters (Å,°): Fe1–N1, 2.007(2); Fe1–Fe3, 2.6632
(7); Fe2–Fe3, 2.5976(7); Fe1–Se1, 2.3281(6); Fe2–Se1, 2.3786(6); Fe3–Se1, 2.3997(6); Fe1–Se2, 2.3656(6); Fe2–
Se2, 2.3901(6); Fe3–Se2, 2.4040(6); Fe1–C12, 1.913(3); Fe1ꢀ ꢀ ꢀC7, 2.757(4); Fe1–Fe3–Fe2, 85.56(2); Fe3–C7–O7,
171.9(4).

Fe/S and Fe/Se clusters with diaminocarbenes
3877
groups. Two semibridging carbonyl groups on the central Fe atom Fe3 are bound to the
edge Fe4 and Fe5 [Fe3–C11, 1.811(4); Fe4–C11, 2.466(4); Fe3–C12, 1.814(4); Fe5–C12,
2.449(4) Å]; the FT–IR data of 14 confirm the presence of the long Fe–COsemibridging
bonds.
The known bow-tie clusters with two closed triiron rings are [nBuN4]2[Fe5(CO)14(µ3-S)2]
[60(a)], [(PPh3)2N]2[Fe5(CO)14(µ3-S)2] [60(b)], [Et4N]3[HFe5(CO)14] [60(c)], and
[Fe5(CO)14(C2R)2] (R = Me, Et) [60(d)]. Moreover, the ‘parent’ cluster corresponding to
11–15, S3Fe5(CO)14 with 20 skeletal electrons (n = 8, the Wade-Mingos rules), is still
unknown [61]. Therefore, the clusters 11–15 with chelating carbene ligands, (μ3-S)2(μ4-S)
Fe5(CO)10(μ-CO)2(κ2N,C-L2) (L2 = Ccarbene–Nheterocycle ligand), are the first example.
Cluster 16 (figure 9) consists of a triangular core of irons with two short Fe–Fe bonds
[Fe2–Fe3, 2.6015(6) Å; Fe1–Fe3, 2.6391(6) Å] and one long Fe–Fe bond [Fe1–Fe2, 2.6714
(5) Å]. The selenide ligand, which is 1.7469(3) Å away from the triiron plane, almost
symmetrically caps the triiron plane. Three terminal carbonyls are on Fe2 and Fe3 and one
terminal carbonyl on Fe1 to which the chelating ligand is bonded. The carbonyl on Fe1
semibridges Fe2 [Fe1–C8, 1.844(3) Å; Fe2–C8, 2.217(3) Å; Fe1–C8–O8, 152.9(2)°;
Fe2–C8–O8, 125.0(2)°; Fe1–C8–Fe2, 81.70(10)°], the presence of which is supported by
the FT-IR data of 16. The terminal carbonyl on Fe1 is bent toward Fe3, with
Fe3ꢀ ꢀ ꢀC1 = 2.742(3) Å and Fe1–C1–O1 = 170.9(3)°. As in 1, the Fe1–C12 bond of 1.994
(2) Å in 16 is a typical Fe–C single bond. Similarly, Fe1–C9 and Fe1–C10 bonds of 2.113
(3) and 2.121(3) Å are single bonds, whereas the C9–C10 bond of 1.386(4) Å has some
double-bond character. The carbene C–N bond lengths are 1.320(3) [C12–N1] and 1.339
(3) Å [C12–N2]. The sum of angles about C12 [Fe1–C12–N1, 116.6(2); Fe1–C12–N2,
126.6(2); N1–C12–N2, 116.9(2)°] is 360.1(2)°, indicating that carbene C12 is
sp2-hybridized. Therefore, these values of the bond lengths and angles show that the C12,
N1, and N2 form a conjugated system. In the case of 16, the carbene C12 acts only as an n
donor. As in 1, the chelating carbene ligand functions as a four-electron donor in a κ3C,C,C
fashion. According to electron-counting rules, each iron conforms to the 18-electron rule.
The carbene C12 lies approximately trans to one arm of the semibridging carbonyl
[C8–Fe1–C12, 160.31(11)°]. The Fe1C9C10 plane forms a dihedral angle of 88.53(18)°
with the carbene CN2 group and the CN2 group forms a dihedral angle of 71.06(14)° with
the phenyl plane. Not surprisingly, as the Se analog of 1, 16 shows similar geometric
parameters.
Cluster 17 (figure 10) has a bent triangle of Fe atoms capped by two Se atoms above and
below with a triiron angle of 85.56(2)° and is the Se analog of 9. The Se2Fe3 core adopts a
distorted square-pyramidal geometry analogous to the previously reported cluster
(μ3-Se)2Fe3(CO)9 [59(a), 62]. In (μ3-Se)2Fe3(CO)9, each of the two Se atoms on the square
base triply bridges the two basal Fe(CO)3 units on the same base and the third Fe(CO)3
group at the apex of the pyramid, and each of the three Fe atoms satisfies the 18-electron
rule. Thereby, 17 may be formally viewed as involving replacement of the two equatorial
carbonyl ligands on one of the iron centers on the square base in (μ3-Se)2Fe3(CO)9 by a
four-electron chelating carbene group, viz. carbene C and pyrimidine N. The carbene ligand
causes significant structural effects, an increase in the triiron bond angle compared with
(μ3-Se)2Fe3(CO)9 [83.21(3)°], and an increase in the Fe–Fe bond-length difference from
0.0121(10) to 0.0656(7) Å. The Fe1–Fe3 and Fe2–Fe3 bond lengths are 2.6632(7) and
2.5976(7) Å whereas those lengths in (μ3-Se)2Fe3(CO)9 are 2.6448(10) and 2.6569(10) Å
[59(a)]. The Fe1–N1 bond length is 2.007(2) Å and practically equals those of 6 and 9. The
Fe1–C12 bond length of 1.913(3) Å is equal to that of 7. The C12–N bond lengths of

3878
Y.-C. Shi et al.
1.365(4) and 1.337(4) Å and the angle sum [359.9(2)°] of the carbene C12 [Fe1–C12–N3,
114.0(2)°; Fe1–C12–N4, 129.8(2)°; N3–C12–N4, 116.1(3)°] indicate the π-electron delocal-
ization over the carbene CN2 group. Because the Fe–CN2 unit is coplanar with the C4H3N2
ring, these atoms form a larger conjugated system resulting in the short Fe–Ccarbene bond.
The chelating ligand makes a dihedral angle of 80.27(14) and 60.07(15)° with the open tri-
iron plane and the phenyl ring, respectively. The Fe3–Se bond lengths of 2.3997(6) and
2.4040(6) Å in 17 are longer than the other Fe–Se bond lengths [2.3281(6)–2.3901(6) Å].
Notably, one of the three carbonyl ligands attached to the apical Fe3 weakly interacts with
the carbene-substituted basal Fe1 from a direction trans to C1O1 [Fe1ꢀ ꢀ ꢀC7, 2.757(4) Å],
leading to nonlinearity of the Fe3–C7–O7 bond angle [Fe3–C7–O7, 171.9(4)°] with car-
bonyl C7 bent toward Fe1.
Each N,Nʹ-disubstituted thiourea can exist in solution as two conformers, resulting from
either a trans or cis orientation of the H–N and C=S bonds with respect to the N–C bond,
namely trans/cis and trans/trans isomers [63], accordingly, the corresponding coordinated
carbene generated from cleavage of the CS bond may also show two types of trans/cis and
trans/trans conformations depicted in chart 2, arising from either a trans or cis orientation
of the H–N and Fe–Ccarbene bonds with respect to the N–Ccarbene bond. However, as shown
in figures 1–6 and 8–10, each exhibits the first type (I) owing to the stabilized intramolecu-
lar hydrogen bonding, viz. trans/cis, the second (II) being excluded due to steric repulsion.
As described below, it is this conformation that involves the self-assembly of each new
cluster.
3.3. Packing modes of clusters
Since assembly based on the H–NCcarbene group as an H-bonding donor and the CO ligand
as an H-bonding acceptor as well as the CO dipole–dipole interactions are rare [64], the
self-assemblies of the clusters described below should be interesting (see Supplementary
Data). Cluster 1 crystallizing in the P21/c space group with a KPI of 69.7 via a
centrosymmetric dimer generated from a [C16–H16ꢀ ꢀ ꢀO5i] hydrogen bond forms a [2 0 1]
infinite 1-D chain linked by an [N1–H1ꢀ ꢀ ꢀO8ii] hydrogen bond (figure 1S) (symmetry
codes: (i) 1 − x, 1 − y, 1 − z; (ii) −1 + x, 3/2 − y, −1/2 + z; C16ꢀ ꢀ ꢀO5i, 3.451(3) Å;
N1–H1, 0.85(3) Å; H1ꢀ ꢀ ꢀO8ii, 2.40(3) Å; N1ꢀ ꢀ ꢀO8ii, 3.192(3) Å; N1–H1ꢀ ꢀ ꢀO8ii, 155(2)°).
ꢀ
Unlike 1, 2 in the P1 space group with a KPI of 68.1 exists in the form of a centrosymmet-
ric dimer generated from a [C9–H9Bꢀ ꢀ ꢀO3i] hydrogen bond (figure 2S) (symmetry code: (i)
1 − x, 1 − y, 1 − z; C9ꢀ ꢀ ꢀO3i, 3.254(10) Å). Cluster 3 crystallizes in the P21/c space group
with a KPI of 67.6 and with two different molecules (3a and 3b) in the asymmetric unit.
Molecules 3a and 3b each form a centrosymmetric dimer generated from [N2–H2ꢀ ꢀ ꢀO7i] or
[N6–H6ꢀ ꢀ ꢀO14ii] hydrogen bonds (figure 3S) (symmetry codes: (i) 1 − x, 1 − y, 1 − z; (ii)
−x, −y, −z; N2–H2, 0.82(3) Å; H2ꢀ ꢀ ꢀO7i, 2.37(3) Å; N2ꢀ ꢀ ꢀO7i, 3.138(5) Å; N2–H2ꢀ ꢀ ꢀO7i,
157(3)°; N6–H6, 0.80(5) Å; H6ꢀ ꢀ ꢀO14ii, 2.34(5) Å; N6ꢀ ꢀ ꢀO14ii, 3.073(5) Å; N6–
H6ꢀ ꢀ ꢀO14ii, 152(5)°). There are no directional interactions between the two dimers. Cluster
4 crystallizing in the I2/a space group with a KPI of 66.9 exists as a centrosymmetric dimer
generated from an [N2–H2ꢀ ꢀ ꢀO7i] hydrogen bond (figure 4S) (symmetry code: (i) 1/2 − x,
i
ꢀ
1/2 − y, 1/2 − z; N2ꢀ ꢀ ꢀO7 , 3.226(4) Å). Unlike 5, 6 crystallizes in the P1 space group with
a KPI of 69.1. The centrosymmetric dimer is generated from a [C10–H10ꢀ ꢀ ꢀO6i] hydrogen
bond. The dimers are connected to form a [0 1 0] infinite chain by an [N3–H3ꢀ ꢀ ꢀO6ii]
hydrogen bond (figure 5S) (symmetry codes: (i) 1 − x, 1 − y, 1 − z; (ii) x, 1 + y, z;

Fe/S and Fe/Se clusters with diaminocarbenes
3879
C10ꢀ ꢀ ꢀO6i, 3.319(5) Å; N3–H3, 0.82(4) Å; H3ꢀ ꢀ ꢀO6ii, 2.57(4) Å; N3ꢀ ꢀ ꢀO6ii, 3.242(5) Å;
N3–H3ꢀ ꢀ ꢀO6ii, 140(4)°). Cluster 7 crystallizes in the P21/c space group with a KPI of 70.6.
The molecules form a (1 0 1) sheet via [N2–H2ꢀ ꢀ ꢀO5i] and [N3–H3Bꢀ ꢀ ꢀO1ii] hydrogen
bonds. These sheets are further packed by an [N3–H3Bꢀ ꢀ ꢀO4iii] hydrogen bond to lead to
an infinite 3-D network (figure 6S) (symmetry codes: (i) −1 + x, 1/2 − y, −1/2 + z; (ii) x, 1/
2 − y, −1/2 + z; (iii) 1 − x, −1/2 + y, 1/2 − z; N2–H2, 0.84(3) Å; H2ꢀ ꢀ ꢀO5i, 2.59(3) Å;
N2ꢀ ꢀ ꢀO5i, 3.310(3) Å; N2–H2ꢀ ꢀ ꢀO5i, 144(3)°; N3–H3B, 0.85(4) Å; H3Bꢀ ꢀ ꢀO1ii, 2.59(4) Å;
N3ꢀ ꢀ ꢀO1ii, 3.191(4) Å; N3–H3Bꢀ ꢀ ꢀO1ii, 129(3)°; N3–H3B, 0.85(4) Å; H3Bꢀ ꢀ ꢀO4iii, 2.54
iii
iii
ꢀ
(4) Å; N3ꢀ ꢀ ꢀO4 , 3.295(4) Å; N3–H3Bꢀ ꢀ ꢀO4 , 148(4)°). Cluster 8 crystallizing in the P1
space group with the disordered CH2Cl2 exists as a centrosymmetric dimer generated from
an [N2–H2ꢀ ꢀ ꢀO1i] hydrogen bond (figure 7S) (symmetry code: (i) 1 − x, 1 − y, 1 − z;
N2–H2, 0.88(3) Å; H2ꢀ ꢀ ꢀO1i, 2.54(4) Å; N2ꢀ ꢀ ꢀO1i, 3.282(3) Å; N2–H2ꢀ ꢀ ꢀO1i, 142(3)°).
Unlike 8, 9 crystallizing in the P21/c space group with a KPI of 68.8 forms a [1 0 0] infinite
chain (figure 8S) via an [N3–H3ꢀ ꢀ ꢀO5i] hydrogen bond (plus C4≡O4ꢀ ꢀ ꢀπ(Cg1i) and
C5≡O5ꢀ ꢀ ꢀπ(Cg2i)) (symmetry code: (i) −1 + x, y, z; Cg1, centroid of the pyrimidyl ring;
Cg2, centroid of the phenyl ring; N3–H3, 0.78(3) Å; H3ꢀ ꢀ ꢀO5i, 2.54(3) Å; N3ꢀ ꢀ ꢀO5i, 3.247
(3) Å; N3–H3ꢀ ꢀ ꢀO5i, 153(3)°; O4ꢀ ꢀ ꢀCg1i, 3.566(3) Å; O5ꢀ ꢀ ꢀCg2i, 3.779(3) Å). Cluster 10
in the Pccn space group with a KPI of 67.7 via a weak [C11–H11ꢀ ꢀ ꢀS2i] hydrogen bond
forms a [0 0 1] infinite chain (symmetry code: (i) 3/2 − x, y, 1/2 + z; C11ꢀ ꢀ ꢀS2i, 3.552(4)
Å). The H bonded to N2 is not involved in H-bonding (figure 9S). Cluster 11 in the P21/c
space group via a [C16–H16ꢀ ꢀ ꢀO9i] hydrogen bond forms a [0 0 1] infinite chain. These
chains are linked along the b axis by a [C25–H25Bꢀ ꢀ ꢀO4ii] hydrogen bond to lead to a
(1 0 0) sheet, viz. 2-D network (figure 10S) (symmetry codes: (i) x, 3/2 - y, 1/2 + z;
(ii) 1 - x, 1/2 + y, 1/2 - z; C16ꢀ ꢀ ꢀO9i, 3.201(7) Å; C25ꢀ ꢀ ꢀO4ii, 3.13(2) Å). The MeOC6H4
group and CH2Cl2 are disordered; therefore, the packing mode only refers to the main part
of 11. Analogous to 10, the H bonded to N2 is not involved in H-bonding. Cluster 12 in
the P21/c space group with a KPI of 67.8 via a centrosymmetric dimer generated from an
[N3–H3ꢀ ꢀ ꢀN4i] intermolecular hydrogen bond forms a (1 0 0) 2-D network linked by an
[N2–H2ꢀ ꢀ ꢀO11ii] intermolecular hydrogen bond (figure 11S) (symmetry codes: (i) 1 − x,
1 − y, 1 − z; (ii) 1 − x, −1/2 + y, 1/2 − z; N3–H3, 0.78(8) Å; H3ꢀ ꢀ ꢀN4i, 2.36(8) Å;
N3ꢀ ꢀ ꢀN4i, 3.062(9) Å; N3–H3ꢀ ꢀ ꢀN4i, 150(8)°; N2–H2, 0.89(8) Å; H2ꢀ ꢀ ꢀO11ii, 2.43(8) Å;
N2ꢀ ꢀ ꢀO11ii, 3.272(10) Å; N2–H2ꢀ ꢀ ꢀO11ii, 159(7)°). Cluster 13 crystallizes in the C2/c
space group with a KPI of 67.8. The centrosymmetric dimer is generated from a weak
[N4–H4Aꢀ ꢀ ꢀO2i] intermolecular hydrogen bond. The dimers are linked via C1ꢀ ꢀ ꢀO2ii and
O1ꢀ ꢀ ꢀC2ii interactions to lead to a [1 1 0] double chain (symmetry codes: (i) 1 − x, 1 − y,
1 − z; (ii) 1/2 − x, 1/2 − y, 1 − z; N4–H4A, 0.94(4) Å; H4Aꢀ ꢀ ꢀO2i, 2.60(4) Å; N4ꢀ ꢀ ꢀO2i,
3.085(4) Å; N4–H4Aꢀ ꢀ ꢀO2i, 113(3)°; C1ꢀ ꢀ ꢀO2ii, 3.128(4) Å; O1ꢀ ꢀ ꢀC2ii, 3.128(4) Å). As
can be seen in figure 12S, because of being shielded by carbonyls in the dimer, the
N4–H4B and N2–H2 groups do not engage in hydrogen bonding. Cluster 14 in the P21/c
space group with a KPI of 65.4 forms a dimer via a [C16–H16ꢀ ꢀ ꢀO6i] intermolecular hydro-
gen bond. These dimers are linked by an O5ꢀ ꢀ ꢀS2ii contact to produce a [0 1 0] double
chain (figure 13S) (symmetry codes: (i) −1 + x, −1 + y, −1 + z; (ii) −x, −1/2 + y, 1/2 − z;
C16ꢀ ꢀ ꢀO6i, 3.397(6) Å; O5ꢀ ꢀ ꢀS2ii, 3.20(1) Å). As shown in figure 13S, the HNCNH unit
only takes part in intramolecular hydrogen bonds. Cluster 15 crystallizes in the P21/c space
group with a KPI of 64.8, with two different molecules (15a and 15b) in the asymmetric
unit. Molecule 15a forms a chain in the c direction via an [N3–H3ꢀ ꢀ ꢀO10i] hydrogen bond
and these chains are linked, along the b axis, via [C16–H16ꢀ ꢀ ꢀO11ii], [N2–H2ꢀ ꢀ ꢀO12ii], and
[C19–H19Aꢀ ꢀ ꢀO12ii] hydrogen bonds to lead to an A sheet. Molecule 15b forms a [0 1 0]

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Y.-C. Shi et al.
chain via [N5–H5ꢀ ꢀ ꢀO23iii], [C37–H37ꢀ ꢀ ꢀO24iii], and [C40–H40Bꢀ ꢀ ꢀO23iii] hydrogen
bonds and these chains are linked, along the c axis, by an [N6–H6ꢀ ꢀ ꢀO22iv] hydrogen bond
to produce an A sheet (figure 14S) (symmetry codes: (i) x, 1/2 − y, −1/2 + z; (ii) −x, 1/
2 + y, 3/2 − z; (iii) 1 − x, −1/2 + y, 3/2 − z; (iv) 1 − x, 1 − y, 1 − z; N3ꢀ ꢀ ꢀO10i, 3.30(2) Å;
C16ꢀ ꢀ ꢀO11ii, 3.398(16) Å; N2ꢀ ꢀ ꢀO12ii, 3.563(14) Å; N5ꢀ ꢀ ꢀO23iii, 3.491(12) Å;
C40ꢀ ꢀ ꢀO23iii, 3.394(16) Å; N6ꢀ ꢀ ꢀO22iv, 3.172(13) Å). Directional interactions between the
sheets are not observed. Cluster 16 shows a packing mode similar to 1. Cluster 16 in the
P21/n space group with a KPI of 69.9 occurs as a centrosymmetric dimer generated from a
i
ꢀ
[C16–H16ꢀ ꢀ ꢀO5 ] hydrogen bond and forms a ½101ꢁ infinite double chain linked by an
[N1–H1ꢀ ꢀ ꢀO8ii] hydrogen bond (symmetry codes: (i) 1 − x, 1 − y, 1 − z; (ii) −1/2 + x, 1/
2 − y, 1/2 + z; C16ꢀ ꢀ ꢀO5i, 3.450(4) Å; N1–H1, 0.79(3) Å; H1ꢀ ꢀ ꢀO8ii, 2.47(3) Å; N1ꢀ ꢀ ꢀO8ii,
3.232(3) Å; N1–H1ꢀ ꢀ ꢀO8ii, 162(3)°). As shown in figure 15S, an [N2–H2ꢀ ꢀ ꢀSe1]
intramolecular H-bond is observed. Cluster 17 crystallizes in the P21/c space group with a
KPI of 69.0. The molecules form a 1-D chain along the a-axis direction via an
[N3–H3ꢀ ꢀ ꢀO5i] hydrogen bond. By an [O2ꢀ ꢀ ꢀO6ii] contact, these 1-D chains are packed in
the c-axis direction to result in (1 0 1) 2-D sheets. As shown in figure 16S, an
[N4–H4ꢀ ꢀ ꢀSe1] intramolecular H-bond is observed (symmetry codes: (i) 1 + x, y, z; (ii) x,
3/2 − y, −1/2 + z; N3–H3, 0.81(3) Å; H3ꢀ ꢀ ꢀO5i, 2.54(3) Å; N3ꢀ ꢀ ꢀO5i, 3.219(4) Å;
N3–H3ꢀ ꢀ ꢀO5i, 141(3)°; O2ꢀ ꢀ ꢀO6ii, 2.893 Å). Cluster 18 in the P212121 space group (ignor-
ing the disordered H2O) gives a [1 0 0] chain via a [C8–H8ꢀ ꢀ ꢀO8i] hydrogen bond (symme-
try code: (i) −1/2 + x, 1/2 − y, 1 − z; C8ꢀ ꢀ ꢀO8i, 3.446(4) Å). As in 11, the H attached to
N2 does not participate in intermolecular hydrogen bonding (figure 17S). According to the
above description, indeed, these new organometallic clusters display an interesting
supramolecular-structure spectrum.
4. Conclusion
Eighteen SFe3, S2Fe3, S3Fe5, SeFe3, and Se2Fe3 clusters with chelating diaminocarbenes
have been synthesized by reactions of substituted thioureas and selenoureas with iron
carbonyls and structurally characterized by X-ray crystallography. By virtue of N–Hꢀ ꢀ ꢀN,
N–Hꢀ ꢀ ꢀO, and C–Hꢀ ꢀ ꢀO intermolecular hydrogen bonds and other non-covalent
interactions, these organometallic clusters display interesting supramolecular structures from
0-D (dimers or tetramers) to 1-D chains, 2-D sheets, or 3-D networks. The reactions of
other thioureas, selenoureas and related thioamides and selenoamides with iron carbonyls
are under investigation.
Supplementary material
CCDC 1043067-1043086 contain the supplementary crystallographic data (including
structure factors) for this article. These data can be obtained free of charge from the
Cambridge Crystallographic Data Center via www.ccdc.cam.ac.uk/data_request/cif.
Disclosure statement
The authors declare no competing financial interest.