Addition of nitrogen-containing heteroallenes to iron(II)-hydrides

Article abstract of DOI:10.1021/om0100030

The reactions between cis-Fe(dmpe)₂H₂ (dmpe = Me₂PCH₂CH₂PMe₂) (1) or cis-Fe(PP₃)H₂ (PP₃ = P(CH₂CH₂PMe₂)₃) (2) and phenyl isothiocyanate (PhNCS), ethyl isothiocyanate (EtNCS), and phenyl isocyanate (PhNCO) were investigated. PhNCS reacts with 1 to form a variety of insertion products at low temperature, and the thermodynamic product hydridoiron N-phenylthioformimidate trans-Fe(dmpe)₂(SCHNPh)H (3a) at 300 K. Addition of an excess of PhNCS to 1 produces the bis(insertion) product trans-Fe(dmpe)₂(SCHNPh)₂ (3c). EtNCS inserts into the iron-hydride bond of 1 to form a mixture of trans-Fe(dmpe)₂(SCHNEt)H (4a, thermodynamic product) and cis-Fe(dmpe)₂(SCHNEt)H (4b, kinetic product). Addition of an excess of EtNCS does not result in a second insertion but rather attack at the thioformimidato ligand to form trans-Fe(dmpe)₂(SCHN⁺(Et)C(S)N^-Et)H (4c). PhNCO reacts rapidly with 1 to form trans-Fe(dmpe)₂(OCHNPh)H (5a) and higher oligomeric products. The addition of PhNCS, EtNCS, and PhNCO to 2 permits the formation of thermally stable, geometrically constrained cis products cis-Fe(PP₃)(SCHNPh)H (6a), cis-Fe(PP₃)(SCHNEt)H (7a), and cis-Fe(PP₃)(OCHNPh)H (8a) in clean reactions. The hydridoiron N-phenylthioformimidate 6a reacts with a second equivalent of PhNCS to form cis-Fe(PP₃)(SCHNPh)₂ (6c), but oligomerization of EtNCS or PhNCO does not occur. All complexes have been characterized by multinuclear NMR and IR spectroscopy and mass spectrometry (electrospray), with elemental analysis or high resolution mass spectrometry confirming the structures of thermally stable complexes where possible. Complexes 3c and 4c were characterized by single-crystal X-ray crystallography.

Full text of DOI:10.1021/om0100030

Organometallics 2001, 20, 3491-3499
3491
Ad d ition of Nitr ogen -Con ta in in g Heter oa llen es to
Ir on (II)-Hyd r id es
Leslie D. Field,* Warren J . Shaw, and Peter Turner
School of Chemistry, University of Sydney, Sydney 2006, New South Wales, Australia
Received J anuary 2, 2001
The reactions between cis-Fe(dmpe)2H2 (dmpe ) Me2PCH2CH2PMe2) (1) or cis-Fe(PP3)H2
(PP3 ) P(CH2CH2PMe2)3) (2) and phenyl isothiocyanate (PhNCS), ethyl isothiocyanate
(EtNCS), and phenyl isocyanate (PhNCO) were investigated. PhNCS reacts with 1 to form
a variety of insertion products at low temperature, and the thermodynamic product
hydridoiron N-phenylthioformimidate trans-Fe(dmpe)2(SCHNPh)H (3a ) at 300 K. Addition
of an excess of PhNCS to 1 produces the bis(insertion) product trans-Fe(dmpe)2(SCHNPh)2
(3c). EtNCS inserts into the iron-hydride bond of 1 to form a mixture of trans-Fe(dmpe)2-
(SCHNEt)H (4a , thermodynamic product) and cis-Fe(dmpe)2(SCHNEt)H (4b , kinetic
product). Addition of an excess of EtNCS does not result in a second insertion but rather
attack at the thioformimidato ligand to form trans-Fe(dmpe)2(SCHN+(Et)C(S)N-Et)H (4c).
PhNCO reacts rapidly with 1 to form trans-Fe(dmpe)2(OCHNPh)H (5a ) and higher oligomeric
products. The addition of PhNCS, EtNCS, and PhNCO to 2 permits the formation of
thermally stable, geometrically constrained cis products cis-Fe(PP3)(SCHNPh)H (6a ), cis-
Fe(PP3)(SCHNEt)H (7a ), and cis-Fe(PP3)(OCHNPh)H (8a ) in clean reactions. The hydridoiron
N-phenylthioformimidate 6a reacts with a second equivalent of PhNCS to form cis-Fe(PP3)-
(SCHNPh)2 (6c), but oligomerization of EtNCS or PhNCO does not occur. All complexes
have been characterized by multinuclear NMR andIR spectroscopy and mass spectrometry
(electrospray), with elemental analysis or high resolution mass spectrometry confirming the
structures of thermally stable complexes where possible. Complexes 3c and 4c were
characterized by single-crystal X-ray crystallography.
In tr od u ction
There is, to date, only a single confirmed report of a
thioformimidato ligand which binds η1 through the
sulfur atom,11 although this form of binding has been
postulated in other cases.5,12,13 There have been no
reports of a formimidato ligand binding η1 through the
oxygen atom. J etz and Angelici10 have reported the
insertion of tert-butyl isocyanate into the iron-hydride
bond of CpFe(CO)2H to form the carboxamido complex
CpFe(CO)2(CONHtBu).
Transition metal hydrides are important compounds
due to their chemical reactivity and importance in
catalysis. The insertion of small unsaturated molecules
into the transition metal hydride bond is an equally
important step in catalytic functionalization reactions.
The insertion of simple heteroallenes, most notably
CO2, into transition metal hydride bonds has received
much recent attention due to their potential usefulness
as C1 building blocks in constructing higher organic
structures. The isocyanate or isothiocyanate functional-
ity is particularly useful as a source of carbon, nitrogen,
and oxygen or sulfur in one chemical step. Isocyanates
(or isothiocyanates) typically insert into a metal-
hydride bond to form formamido (or thioformamido)
ligands which bind to the metal in an η2 fashion through
We have recently reported the propensity of iron(II)
dihydride complexes with phosphine donor ligands to
insert the heteroallenes CO2, CS2, and COS into both
iron-hydride bonds.14 In this paper, we report insertion
and further reactions of the heteroallenes phenyl isothio-
cyanate (PhNCS), ethyl isothiocyanate (EtNCS), and
phenyl isocyanate (PhNCO) with the iron(II)-hydride
bonds of the related iron phosphine complexes cis-
Fe(dmpe)2H2 (dmpe ) Me2PCH2CH2PMe2) (1) and cis-
Fe(PP3)H2 (PP3 ) P(CH2CH2PMe2)3) (2).
both nitrogen and oxygen1-5 (or nitrogen and sulfur5-7
)
atoms. Examples of binding η1 through the nitrogen
atom8 and η1 through the carbonyl moiety to form a
carboxamido ligand9,10 are also known.
(8) Weinmann, M.; Walter, O.; Huttner, G.; Lang, H. J . Organomet.
Chem. 1998, 561, 131.
(1) Sahajpal, A.; Robinson, S. D. Inorg. Chem. 1979, 18, 3572.
(2) Robinson, S. D.; Sahajpal, A. J . Organomet. Chem. 1979, 164,
C9.
(3) Lyons, D.; Wilkinson, G.; Tornton-Pett, M.; Hursthouse, M. B.
J . Chem. Soc., Dalton Trans. 1984, 695.
(4) Gibson, V. C.; Kee, T. P. J . Organomet. Chem. 1994, 471, 105.
(5) Leboeuf, J . F.; Leblanc, J . C.; Moise, C. J . Organomet. Chem.
1987, 335, 331.
(6) Robinson, S. D.; Sahajpal, A. Inorg. Chem. 1977, 16, 2722.
(7) Robinson, S. D.; Sahajpal, A. J . Organomet. Chem. 1976, 111,
C26.
(9) J etz, W.; Angelici, R. J . J . Am. Chem. Soc. 1972, 94, 3799.
(10) J etz, W.; Angelici, R. J . J . Organomet. Chem. 1972, 35, C37.
(11) McEneaney, P. A.; Spalding, T. R.; Ferguson, G. J . Chem. Soc.,
Dalton Trans. 1997, 145.
(12) Herberich, G. E.; Mayer, H. J . Organomet. Chem. 1987, 322,
C29.
(13) Antinolo, A.; Carrillo-Hermosilla, F.; Garcia-Yuste, S.; Freitas,
M.; Otero, A.; Prashar, S.; Villasenor, E.; Fajardo, M. Inorg. Chim.
Acta 1997, 259, 101.
(14) Field, L. D.; Lawrenz, E. T.; Shaw, W. J .; Turner, P. Inorg.
Chem. 2000, 39, 5632.
10.1021/om0100030 CCC: $20.00 © 2001 American Chemical Society
Publication on Web 07/12/2001

3492 Organometallics, Vol. 20, No. 16, 2001
Field et al.
1
Ta ble 1. Su m m a r y of H, 31P , 13C NMR a n d IR Da ta for Com p lexes 1-8A
1H
IR
compound
cis-Fe(dmpe)2H2 (1)
cis-Fe(PP3)H2 (2)
trans-Fe(dmpe)2(SCHNPh)H (3a )
cis-Fe(dmpe)2(SCHNPh)H (3b)
hydride
FeXCHN
31P
13C (C ) X)
M-H
1777
1828, 1713
1789
ν(XCHN)
-14.33
-11.03
-24.93
-11.46
83.7, 74.1
187.2, 68.7
70.7
56.2, 67.6,
72.6, 74.6
60.3
9.49
8.71
177.8
1590, 2900
trans-Fe(dmpe)2(SCHNPh)2 (3c)
trans-Fe(dmpe)2(SCHNEt)H (4a )
cis-Fe(dmpe)2(SCHNEt)H (4b)
8.76
9.03
8.71
174.2
172.4
181.7
1593, 2898
1540, 2898
-25.38
-11.33
71.3
1785
1811
54.9, 66.5,
71.0, 73.1
68.5
trans-Fe(dmpe)2(SC(H)N+(Et)C(S)N-(Et))H (4c)
-24.47
11.06
169.8, 193.5
984, 1225,
1551, 2900
1595, 2903
1494, 2897
trans-Fe(dmpe)2(OCHNPh)H (5a )
cis-Fe(PP3)(SCHNPh)H (6a )
-34.31
-14.05
8.13
9.70
70.7
167.8
178.7
1792
1802
180.4 (PA),
62.8 (PT),
60.8 (PE)
178.4 (PA),
73.3 (PE),
53.6 (PT)
181.0 (PA),
62.8 (PT),
61.2 (PE)
173.3 (PA),
56.2 (PT),
55.1 (PE)
cis-Fe(PP3)(SCHNPh)2 (6b)
cis-Fe(PP3)(SCHNEt)H (7a )
cis-Fe(PP3)(OCHNPh)H (8a )
9.26, 9.63
9.31
176.4, 176.8
173.6
1590, 2903
1543, 2898
1571, 2900
-13.92
-13.07
1803
1794
8.81
170.3
Sch em e 1
The reaction between cis-Fe(dmpe)2H2 (1) and phenyl
isothiocyanate was carried out at lower temperature in
tetrahydrofuran-d8. Reaction was initiated only at tem-
peratures higher than 260 K, at which point 1H NMR
suggested the reaction mixture contained five prod-
ucts: trans-Fe(dmpe)(SCHNPh)H (3a , major product)
and four other minor products with iron-hydride and
thioformimidato proton resonances at δ -11.46 (ddt,
2J PH ) 31, 54, 64 Hz) and δ 8.71 (3b, cis stereochemis-
2
try), δ -10.15 and δ 9.63 (cis), δ -25.38 (p, J PH ) 50
Resu lts a n d Discu ssion
2
Hz) and δ 8.33 (trans), and δ -23.43 (p, J PH ) 51 Hz)
A solution of cis-Fe(dmpe)2H2 (1) in benzene-d6,
toluene-d8, or tetrahydrofuran-d8 reacted with phenyl
isothiocyanate (PhNCS, 1 equiv) at 300 K to form the
insertion product trans-Fe(dmpe)2(SCHNPh)H (3a )
(Scheme 1, Table 1).
and δ 11.17 (trans).
Product 3b was the most stable of these, and re-
mained stable in solution at temperatures up to 280 K,
and is probably cis-Fe(dmpe)(SCHNPh)H, the expected
intermediate in the formation of 3a . The 31P{1H} NMR
spectrum of 3b exhibits four 8-line multiplet resonances
at δ 56.2 (dt), 67.6 (ddd), 72.6 (ddd), and 74.6 (dt) for
four inequivalent 31P nuclei, confirming the cis stereo-
chemistry.14
The 31P{1H} NMR spectrum of trans-Fe(dmpe)2-
(SCHNPh)H (3a ) comprises a singlet resonance at δ 70.7
(Table 1), indicating a trans geometry for the dmpe
1
ligands about the iron center. The H NMR spectrum
of 3a exhibits a high-field pentet at δ -24.93 due to the
metal-bound hydride coupled to four equivalent 31P
nuclei (2J PH ) 50 Hz) and a singlet at δ 9.49, indicative
of a thioformamido or thioformimidato proton.4
The ligand formed upon insertion of phenyl isothio-
cyanate into the iron-hydride bond can bind to the iron
center in an η1 fashion through either the sulfur
(thioformimidato ligand) or the nitrogen (thioformamido
ligand) atom or in an η2 fashion (thioformamido ligand).
The trend in chemical shift for hydrides trans to sulfur,
oxygen, and phosphorus atoms in iron(II) complexes of
this type (containing formate, dithioformate, or thio-
formate ligands) has been established.14 3a exhibits an
η1 S-bound thioformimidato ligand as evidenced by the
characteristic chemical shift (δ -24.93) for a hydride
trans to an S-donor.
The other products formed at low temperature, one
cis and two trans products, could not be characterized
further and are presumably unstable isomers of 3b
which contain the thioformimidato ligand in a different
binding mode, such as η1 or η2 thioformamido.
The addition of a second equivalent (or indeed excess)
of PhNCS to 3a or 3b at a variety of temperatures
resulted in the formation of a single product, trans-
Fe(dmpe)2(SCHNPh)2 (3c), the product of insertion of
phenyl isothiocyanate into the second iron-hydride
bond of 1 (Scheme 2). The cis isomer, cis-Fe(dmpe)2-
(SCHNPh)2, was not detected.
The 31P{1H} NMR spectrum of 3c exhibits a singlet
1
at δ 60.3. The H NMR spectrum displays equivalent
thioformimidato proton resonances at δ 8.76. IR spec-
troscopy gave evidence only for thioformimidato ligands
in the product (no metal hydrides) while the 13C{1H}
NMR spectrum exhibited a 31P coupled pentet at δ 174.2
(3J CP ) 6 Hz) for equivalent imido carbon nuclei (Table
1).
The 13C{1H} NMR spectrum of 3a exhibited a singlet
at δ 177.8 for the imido carbon, while the IR spectrum
(KBr disk) of 3a confirmed the presence of a thio-
formimidato ligand with two bands at 1590 (CdN
stretch) and 2900 (thioformimidato C-H stretch) cm-1 4,13
.

N-Containing Heteroallene Addition to Fe(II)-Hydrides
Organometallics, Vol. 20, No. 16, 2001 3493
Ta ble 4. Cr ysta llogr a p h ic Da ta for
tr a n s-F e(d m p e)2(SCHNP h )2 (3c) a n d
Sch em e 2
tr a n s-F e(d m p e)2(SC(H)N+(Et)C(S)N-(Et))H (4c)
3c
4c
emperical formula
formula weight
crystal system
crystal habit
crystal color
space group
Z value
C
26H44FeN2P4S2
C21H44FeN2P4S2
568.43
triclinic
prism
red
P1h (No. 2)
2
628.48
monoclinic
blade
dark brown
P21/c (No. 14)
2
a (Å)
b (Å)
c (Å)
10.669(3)
9.176(3)
16.199(5)
10.435(2)
16.783(4)
9.226(2)
104.933(7)
92.245(8)
98.482(7)
1539.1(6)
21
0.710 73
0.845
1.227
0.0498
0.1534
0.772, 0.926
(Gaussian)
12 535
6847
4949 (I > 2σ(I))
0.0335
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for tr a n s-F e(d m p e)2(SCHNP h )2 (3c)
R (deg)
bond distances (Å)
bond angles (deg)
â (deg)
104.836(5)
Fe(1)-P(1)
2.2547(8)
P(2)-Fe(1)-P(1)
(intra-ligand)
86.05(2)
γ (deg)
V (Å3)
1533.0(8)
-100
0.710 73
0.856
1.362
0.0318
Fe(1)-P(2)
Fe(1)-S(1)
S(1)-C(7)
C(7)-N(1)
N(1)-C(8)
2.2529(7)
2.3213(7)
1.7108(18)
1.283(2)
P(1)-Fe(1)-S(1)
P(2)-Fe(1)-S(1)
Fe(1)-S(1)-C(7)
S(1)-C(7)-N(1)
C(7)-N(1)-C(8)
84.42(2)
85.04(3)
128.15(6)
130.42(14)
118.41(15)
T (°C)
λ (Mo KR, Å)
µ (Mo KR, mm-1
)
Fcalcd (g cm-3
R1(F)a
)
1.420(2)
wR2(F2)a
Tmin,max
0.0810
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for tr a n s-
0.853, 1.000
(SADABS)
13 795
3617
3311 (I > 2σ(I))
0.0208
F e(d m p e)2(SC(H)N+(Et)C(S)N-(Et))H (4c)
N
Nind
Nobs
Rmerge
bond distances (Å)
bond angles (deg)
Fe(1)-P(1)
2.2024(10)
2.1998(10)
2.1990(10)
2.1964(10)
2.2927(9)
1.667(3)
1.314(4)
1.503(5)
1.401(7)
1.475(4)
1.705(4)
1.273(5)
1.469(4)
1.388(7)
P(1)-Fe(1)-P(2)
85.18(4)
94.24(4)
168.86(4)
171.47(4)
90.46(4)
100.67(4)
114.83(11)
127.4(2)
120.6(3)
120.3(3)
119.0(3)
118.3(3)
110.9(3)
130.7(3)
117.2(4)
Fe(1)-P(2)
Fe(1)-P(3)
Fe(1)-P(4)
Fe(1)-S(1)
S(1)-C(1)
C(1)-N(1)
N(1)-C(2)
C(2)-C(3)
N(1)-C(4)
C(4)-S(2)
C(4)-N(2)
N(2)-C(5)
C(5)-C(6)
P(2)-Fe(1)-P(3)
P(1)-Fe(1)-P(3)
P(2)-Fe(1)-P(4)
P(1)-Fe(1)-S(1)
P(3)-Fe(1)-S(1)
Fe(1)-S(1)-C(1)
S(1)-C(1)-N(1)
C(1)-N(1)-C(2)
C(1)-N(1)-C(4)
C(4)-N(1)-C(2)
N(1)-C(4)-S(2)
N(1)-C(4)-N(2)
S(2)-C(4)-N(2)
C(4)-N(2)-C(5)
a
2
R1 ) Σ||Fo| - |Fc||/Σ|Fo| for Fo > 2σ( Fo); wR2 ) (Σw(Fo
Fc2)2/Σ(w Fc2)2)1/2, all reflections w ) 1/[σ2(Fo2) + (0.0508P)2
-
+
1.8264P] for 3c and w ) 1/[σ2(Fo2) + (0.0927P)2] for 4c where P )
2
(Fo + 2Fc2)/3.
1:1.25. With heat or standing, complete conversion from
4b to 4a was observed within 3 h.
The 31P{1H} NMR spectrum of trans-Fe(dmpe)2-
(SCHNEt)H (4a ) exhibited a singlet at δ 71.3, while the
1H NMR spectrum exhibited a high-field pentet at δ
-25.38 for a hydride coupled to four equivalent 31P
nuclei (2J PH ) 51 Hz) and trans to a sulfur donor. A
singlet at δ 9.03 was indicative of a thioformimidato
proton. The 13C{1H} NMR spectrum of 4a exhibited a
phosphorus-coupled pentet at δ 172.4 (3J CP ) 5 Hz) for
the imido carbon. IR spectroscopy of the stable trans
product confirmed the presence of an N-ethylthio-
formimidato ligand.
The 31P{1H} NMR spectrum of cis-Fe(dmpe)2-
(SCHNEt)H (4b) exhibited four 8-line multiplets for four
inequivalent 31P centers at δ 54.9, 66.5, 71.0, and 73.1.
The 1H NMR spectrum displayed a multiplet at δ
-11.33 for a hydride trans to a phosphorus donor and
coupled to four inequivalent 31P centers and a singlet
at δ 8.71 for the thioformimidato proton.
When a further equivalent of EtNCS was added to
4a or 4b, the product of insertion into the second iron-
hydride bond of 1 was not detected. Quantitative
conversion of 4a or 4b to a new product 4c, containing
a hydride resonating as a phosphorus-coupled pentet
(2J PH ) 50 Hz) at δ -24.47 (trans to a sulfur atom) and
equivalent 31P environments (δ 68.5), was observed
(Scheme 4). The 13C{1H} NMR spectrum featured an
imido carbon resonance at δ 169.8 and a further
resonance at δ 193.5 which is consistent with a thio-
carbonyl carbon.14 IR indicated the presence of an iron-
hydride and both CdN and CdS functionalities.
Dark brown bladelike single crystals of trans-
Fe(dmpe)2(SCHNPh)2 (3c), suitable for structure deter-
mination by X-ray crystallography, were grown in
benzene-d6. Selected bond lengths and angles are listed
in Table 2 and crystallographic data are listed in Table
4. The dmpe ligand backbone adopts at least two
different orientations (Figure 1), with disordered site
populations refined and then fixed at 0.5. The structure
confirmed the presence of two η1 S-bound thioform-
imidato ligands in a trans disposition, the first example
of such binding to a first-row transition metal. Only one
other structurally characterized example of an η1
S-bound thioformimidato ligand, the rhodacarborane
3-(η1-SCHNPh)-3,3-(PMe2Ph)2-3,1,2-closo-RhC2B9H11, is
known.11 The CdN (1.283(2) Å) and C-S (1.7108(18)
Å) bond lengths and NCS (130.42(14)°) bond angle of
3c compare favorably with those of the rhodacarborane
(1.254(4) Å, 1.724(3) Å, and 126.7(2)° respectively).
A solution of cis-Fe(dmpe)2H2 (1) in benzene-d6,
toluene-d8, or tetrahydrofuran-d8 reacted with ethyl
isothiocyanate (EtNCS, 1 equiv) at a variety of temper-
atures to form a mixture of the insertion products trans-
Fe(dmpe)2(SCHNEt)H (4a) and cis-Fe(dmpe)2(SCHNEt)H
(4b) (Scheme 3). The cis isomer 4b, an intermediate in
the formation of 4a , was the dominant product at lower
temperatures (kinetic product), and at 300 K the im-
mediate ratio of products 4a :4b in the reaction was
Red prismatic single crystals of 4c of suitable quality
for structure determination by X-ray crystallography

3494 Organometallics, Vol. 20, No. 16, 2001
Field et al.
F igu r e 2. ORTEP15 diagram of the complex trans-
Fe(dmpe)2(SC(H)N+(Et)C(S)N-(Et))H (4c) (20% atomic dis-
placement ellipsoids).
The dimerized ligand is formally zwitterionic and
contains both quaternary (positive) and anionic nitrogen
centers. The outer C-S bond length of 1.705(4) Å
suggests a C-S single bond and indicates that the
negative charge of the zwitterion is probably delocalized
over the outer S-C-N moiety in the solid state.
trans-Fe(dmpe)2(SC(H)N+(Et)C(S)N-(Et))H (4c) is for-
mally the product of nucleophilic attack by the lone pair
on the nitrogen of the N-ethylthioformimidato ligand
of 4a at the thiocarbonyl carbon of EtNCS. The complex
4c represents the product of the initial step in a possible
polymerization of EtNCS at an iron(II) center; however
no higher order oligomers of EtNCS were detected (by
NMR or electrospray MS) in this reaction. Transition
metal catalysts for the oligomerization (or polymeriza-
tion) of isothiocyanates and isocyanates are relatively
rare.16-19 Notable examples include a titanium complex,
TiCl3(OCH2CF3), which has been reported to polymerize
alkyl isocyanates in a “living” fashion,20 and Ru(CCC6H9)-
(PMe3)2(Cp) which forms tri- and poly(methylisocyanate)
products from methyl isocyanate.21
F igu r e 1. ORTEP15 diagram of the complex trans-
Fe(dmpe)2(SCHNPh)2 (3c) (20% atomic displacement el-
lipsoids). The molecule resides on an inversion site.
Sch em e 3
Sch em e 4
A solution of cis-Fe(dmpe)2H2 (1) in benzene-d6 or
tetrahydrofuran-d8 reacted with phenyl isocyanate
(PhNCO) at 300 K to form a mixture of the insertion
product trans-Fe(dmpe)2(OCHNPh)H (5a ), four other
1
products (containing hydrides with H NMR resonances
(15) J ohnson, C. K. ORTEPII, Report ORNL-5138; Oak Ridge
National Laboratories: Oak Ridge, TN, 1976.
(16) Bur, A. J .; Fetters, L. J . Chem. Rev. 1976, 76, 727.
(17) Kashiwagi, T.; Hidai, M.; Uchida, Y.; Misono, A. J . Polym. Sci.,
B: Polym. Lett. 1970, 8, 173.
(18) Graham, J . C.; Xu, X.; J ones, L.; Orticochea, M. J . Polym. Sci.,
A: Polym. Chem. 1990, 28, 1179.
were grown from benzene-d6, and 4c was identified as
trans-Fe(dmpe)2(SC(H)N+(Et)C(S)N-(Et))H (Figure 2).
Selected bond lengths and angles are listed in Table 3,
and crystallographic data are listed in Table 4.
The X-ray structure of 4c shows that the dimerized
ligand is bound η1 through the sulfur atom, indirectly
confirming the structure of trans-Fe(dmpe)2(SCHNEt)H
(4a ) as having an η1 S-bound thioformimidato ligand.
(19) Yilmaz, O.; Usanmaz, A.; Alyuruk, K. J . Polym. Sci., C: Polym.
Lett. 1990, 28, 341.
(20) Patten, T. E.; Novak, B. M. J . Am. Chem. Soc. 1991, 113, 5065.
(21) Selegue, J . P.; Young, B. A.; Logan, S. L. Organometallics 1991,
10, 1972.

N-Containing Heteroallene Addition to Fe(II)-Hydrides
Organometallics, Vol. 20, No. 16, 2001 3495
Sch em e 5
Sch em e 6
similar to those of 5a ) in solution, and a red oily
precipitate (Scheme 5). Notably, at least 1.5 equiv of
PhNCO was required to completely convert cis-
Fe(dmpe)2H2 (1) to products, indicating a high reactivity
of the initial thermodynamic product 5a . When the
reaction was carried out at low temperature, up to eight
unstable products with cis geometries for the phosphine
ligands were formed, each in very small amounts
compared to the formation of 5a .
(dmpe)2H2,26,27 Fe(BPE5)2Cl2 (BPE5 ) 1,2-bisphospho-
lanoethane),28 or as an equilibrating mixture of the two,
e.g., Fe(dprpe)2Cl2 (dprpe ) 1,2-bisdi(n-propyl)phos-
phinoethane),29 Fe(dmpe)2(SR)2.30
A stable cis stereochemistry was imposed on the metal
system, by replacement of the two dmpe ligands with
the tetradentate phosphine ligand P(CH2CH2PMe2)3
(PP3). Addition of 1 equiv of PhNCS, EtNCS, or PhNCO
in benzene-d6 to a benzene-d6 solution of cis-Fe(PP3)H2
(2) at 300 K resulted in a clean quantitative reaction to
form cis-Fe(PP3)(SCHNPh)H (6a), cis-Fe(PP3)(SCHNEt)H
(7a ), or cis-Fe(PP3)(OCHNPh)H (8a ), respectively
(Scheme 6).
The 31P{1H} NMR spectrum of cis-Fe(PP3)(SCHNPh)H
(6a ) is typical of most octahedral complexes of the type
cis-Fe(PP3)XY,31,32 showing a characteristic doublet of
triplet resonance for the apical, central phosphorus of
the chelating PP3 ligand (PA) at δ 180.4, with signals
at δ 62.8 and 60.8 for the axial terminal phosphorus
resonances (PT) and the equatorial terminal phosphorus
resonance (PE), respectively. The 1H NMR spectrum
exhibited a one-proton resonance at δ 9.70 for the
thioformimidato proton, and this is somewhat downfield
from the corresponding protons in Fe(dmpe)2(SCHNPh)H
(3a ,b) and trans-Fe(dmpe)2(SCHNPh)2 (3c). The 1H
NMR spectrum also exhibits a doublet of doublets of
triplets resonance at δ -14.05 for a hydride coupled to
three different 31P environments and at a chemical shift
characteristic of a hydride trans to a phosphorus donor.
In the 13C{1H} NMR spectrum, a CdN resonance
appears at δ 178.7. For the alternate N-coordinated
isomer, the spectrum would exhibit a CdS resonance
in the range δ 200-250.14 IR stretches at 1494 (CdN
stretch) and 2897 (thioformimidate C-H stretch) cm-1
also confirm an η1 S-bound N-phenylthioformimidato
ligand.
The 31P{1H} NMR spectrum of trans-Fe(dmpe)2-
1
(OCHNPh)H (5a ) exhibited a singlet at δ 70.7. The H
NMR spectrum exhibited a high-field pentet at δ -34.31
for a hydride coupled to four equivalent 31P nuclei (2J PH
) 49 Hz) and trans to an oxygen donor14 and a
formimidato proton resonance at δ 8.13. The imido
carbon resonated at δ 167.8 in the 13C{1H} NMR
spectrum. IR spectroscopy of a partially purified mixture
containing mostly (>90%) 5a confirmed the presence of
an N-phenylformimidato ligand.
Electrospray mass spectrometry of the product mix-
ture and of the oily precipitate showed a parent ion (M
- 1)+ at 476 (M ) 5a ), a peak at 595 (M + PhNCO -
1)+, and some higher mass peaks which do not obviously
correspond to products containing higher order oligo-
mers of PhNCO. The cation with a mass of 595 amu
probably corresponds to the product trans-Fe(dmpe)2-
(OC(H)N+(Ph)C(O)N-(Ph))H, by analogy with the for-
mation of 4c from 4a .
The insertion of isothiocyanates and isocyanates into
the metal-hydride bond in this work resulted exclu-
sively in Fe-S or Fe-O bonded products rather than
metal-N bonded products. This observation is consist-
ent with previous observations of hydridoiron thio-
formates.14 The selectivity for S or O binding over N
binding in these potentially ambident donors probably
involves the affinity of the relatively soft Fe(II) center
for the softer S or O centers. Steric factors may also play
a role since the sterically more encumbered CdN-R
fragment is directed away from the metal center with
O- or S-binding of the thioformimidate fragment.
No thermally stable products with a cis disposition
of the two dmpe ligands were observed in this work. Iron
complexes containing two bidentate phosphine ligands
are well-known to be stereochemically labile with ready
interconversion of cis and trans isomers at or near room
temperature. The relative stability of the Fe(PP)2X2
complexes can be rationalized by the fine balance
between steric and electronic factors. The substituted
tertiary phosphines are crowded at the Fe(II) center,
and depending on the bulk of the substituents on P and
the nature of X ligands, Fe(PP)2X2 complexes have been
characterized with either trans stereochemistry, e.g.,
Fe(dmpe)2Cl2,22 Fe(dmpe)2HCl,23 Fe(dmpe)2(CCR)2,24
[Fe(dmpe)2(H2)H]+,25 cis stereochemistry, e.g., Fe-
(22) Baker, M. V.; Field, L. D.; Hambley, T. W. Inorg. Chem. 1988,
27, 2872.
(23) Baker, M. V.; Field, L. D. J . Organomet. Chem. 1988, 354, 351.
(24) Field, L. D.; George, A. V.; Hambley, T. W.; Malouf, E. Y.;
Young, D. J . J . Chem. Soc., Chem. Commun. 1990, 931.
(25) Baker, M. V.; Field, L. D.; Young, D. J . J . Chem. Soc., Chem.
Commun. 1988, 546.
(26) Meakin, P.; Muetterties, E. L.; J esson, J . P. J . Am. Chem. Soc.
1973, 95, 75.
(27) Baker, M. V.; Field, L. D. J . Am. Chem. Soc. 1986, 108, 7433.
(28) Field, L. D.; Thomas, I. P.; Hambley, T. W.; Turner, P. Inorg.
Chem. 1998, 37, 612.
(29) Field, L. D.; Baker, M. V.; Young, B. A. J . Appl. Organomet.
Chem. 1990, 4, 551.
(30) Field, L. D.; Boyd, S. E.; Hambley, T. W.; Young, D. J . Inorg.
Chem. 1990, 29, 1496.
(31) Field, L. D.; Messerle, B. A.; Smernik, R. J . Inorg. Chem. 1997,
36, 5984.
(32) Field, L. D.; Messerle, B. A.; Smernik, R. J .; Hambley, T. W.;
Turner, P. Inorg. Chem. 1997, 36, 2884.

3496 Organometallics, Vol. 20, No. 16, 2001
Field et al.
The 31P{1H} NMR spectrum of cis-Fe(PP3)(SCHNEt)H
(7a ) exhibited a doublet of triplets (2J PP ) 30, 24 Hz) at
δ 181.0 (PA), a doublet of doublets (2J PP ) 30, 24 Hz) at
δ 62.8 (PT), and a quartet (2J PP ) 24 Hz) at δ 61.2 (PE).
The addition of an excess of EtNCS or PhNCO to cis-
Fe(PP3)(SCHNEt)H(7a) and cis-Fe(PP3)(OCHNPh)H (8a),
respectively, results in neither insertion into the second
iron-hydride bond nor oligomerization of the substrate.
One extra equivalent of the substrate resulted in no
reaction, while a large excess only produced previously
observed decomposition products for complexes of this
type.14
1
The H NMR spectrum exhibited a resonance at δ 9.31
for the thioformimidato proton and a doublet of doublets
of triplets resonance at δ -13.92 for the metal hydride.
The imido carbon resonance at δ 173.6 in the 13C{1H}
NMR spectrum and IR stretches at 1543 and 2898
cm-1 again confirm the presence of an η1 S-bound
N-ethylthioformimidato ligand.
Con clu sion s
Iron dihydrides of the type FeP4H2 react rapidly with
PhNCS, EtNCS, and PhNCO, producing stable hydrido-
iron (η1-S)-thioformimidates and (η1-O)-formimidates. In
the case of cis-Fe(dmpe)2H2 (1), cis intermediates isomer-
ized to the thermally stable trans insertion products at
room temperature or below. Evidence from low-temper-
ature spectroscopy of the reactions suggested the initial
formation of intermediates that involved bonding of the
substrate to the iron center in another mode (η1-N, η1-
C, or η2-N, O, or S). The reactivity of each of the
substrates PhNCS, EtNCS, and PhNCO was clearly
different, and in the presence of excess reagent, products
of second insertion and dimerization of the thioform-
imidate or formimidate ligand were characterized.
The tendency for transition metal hydrides to react
by insertion of unsaturated substrates is well estab-
lished through studies by Berke et al.,34 and metal
hydride reactivity has been correlated to the degree of
polarization of the transition metal hydride bond (the
“hydridicity” of the hydride ligand). The transition metal
hydrides which are most reactive toward insertion
characteristically contain a hydride disposed trans to a
strong π-acceptor ligand (e.g., carbonyl, nitrosyl, car-
byne),34 and transition metal hydrides of this type are
known to insert aldehydes, ketones, and even imines.
We have clearly established the reactivity of the
complexes cis-Fe(dmpe)2H2 (1) and cis-Fe(PP3)H2 (2)
toward the heteroallenes CO2, COS, CS2,14 PhNCS,
EtNCS, and PhNCO. The propensity of the iron com-
plexes studied in this work to insert heteroallenes places
them among the highly reactive metal hydrides. The
polarized iron-hydride bond is due to the low electro-
negativity at the iron center caused by four strongly
σ-donating phosphines.35-37
The 31P{1H} NMR spectrum of cis-Fe(PP3)(OCHNPh)H
(8a ) exhibited a doublet of triplets (2J PP ) 33, 23 Hz) at
δ 173.3 (PA), a doublet of doublets (2J PP ) 33, 23 Hz) at
δ 56.2 (PT), and a quartet (2J PP ) 23 Hz) at δ 55.1 (PE).
1
The H NMR spectrum exhibited a resonance at δ 8.81
for the formimidato proton and a doublet of doublets of
triplets resonance at δ -13.07 for the metal-bound
hydride. The imido carbon resonance at δ 170.3 in the
13C{1H} NMR spectrum, the IR stretches at 1571 and
1
2900 cm-1, and the comparison of 31P and H NMR data
with that of the known cis-Fe(PP3)(OCHO)H14 confirm
the presence of an η1 O-bound N-phenylformimidato
ligand.
2D NOESY and COSY nmr,31,32 and X-ray crystal-
lography33 have been used to determine the geometry
of cis-Fe(PP3)XH complexes, and for all complexes of this
type studied to date, the metal-bound hydride ligand
has been located exclusively in a position cis to the
apical phosphorus PA. The downfield chemical shift,
splitting pattern and proton-phosphorus couplings con-
firm that cis-Fe(PP3)(SCHNPh)H (6a ), cis-Fe(PP3)-
(SCHNEt)H(7a ), and cis-Fe(PP3)(OCHNPh)H (8a ) also
have this stereochemistry.
The addition of a further equivalent (or an excess) of
PhNCS to a solution of cis-Fe(PP3)(SCHNPh)H (6a ) in
benzene-d6 results in the rapid formation of a cream-
colored precipitate. This product was insoluble in most
solvents and only partially soluble in tetrahydrofuran
and acetonitrile. The 31P{1H} NMR spectrum shows the
formation of two products in the approximate ratio of
2.5:1. The major product exhibits an apparent quartet
(J ) 23 Hz) at δ 178.4 (PA), a doublet of triplets (J )
42, 23 Hz) at δ 73.3 (terminal phosphorus PE), and a
doublet of doublets (J ) 42, 23 Hz) at δ 53.6 (equivalent
terminal phosphorus donors PT). The large upfield shift
of PE (relative to 6a ) is consistent with PE being trans
to an N-phenylthioformimidato ligand rather than a
hydride in the coordination sphere,14 and the major
product is assigned as cis-Fe(PP3)(SCHNPh)2 (6b). The
minor product exhibited similar 31P NMR shifts at δ
176.8 (PA, q, J ) 24 Hz), δ 73.0 (PE, dt, J ) 42, 23 Hz),
and δ 53.7 (PT, dd, J ) 42, 23 Hz) and is possibly an
Exp er im en ta l Section
All manipulations were carried out using standard Schlenk,
high vacuum, and glovebox techniques. Air-sensitive NMR
samples were prepared in a nitrogen- or argon-filled glovebox,
with solvent vacuum transferred into an NMR tube fitted with
a concentric Teflon valve. Toluene-d8, tetrahydrofuran-d8, and
benzene-d6 were dried over sodium/benzophenone and vacuum
distilled immediately prior to use. Ether was dried over sodium
wire before distillation under nitrogen from sodium/benzo-
phenone. Nitrogen (>99.5%) was used as supplied without
1
isomer of 6b. The H NMR spectrum of the dominant
product 6b exhibited the resonances of two nonequiva-
lent thioformimidato protons at δ 9.26 (trans to PA) and
δ 9.63 (trans to PE), while the 13C{1H} NMR spectrum
exhibited resonances at δ 176.8 and 176.4 for imido
carbons trans and cis to PA, respectively. The high-
resolution electrospray mass spectrum showed a single
parent ion with a mass of 625.1011 (M - 1)+ (M ) 6b),
with no further evidence for the possible structure of
the minor product.
(34) See, for example: (a) Berke, H.; Burger, P. Comments Inorg.
Chem. 1994, 16, 279. (b) Furno, F.; Fox, T.; Schmalle, H. W.; Berke,
H. Organometallics 2000, 19, 3620. (c) Liang, F.; J acobsen, H.;
Schmalle, H. W.; Fox, T.; Berke, H. Organometallics 2000, 19, 1950.
(35) Gusev, D. G.; Nietlispach, D.; Eremenko, I. L.; Berke, H. Inorg.
Chem. 1993, 32, 3628.
(36) Nietlispach, D.; Veghini, D.; Berke, H. Helv. Chim. Acta 1994,
77, 2197.
(37) van der Zeijden, A. A. H.; Sontag, C.; Bosch, H. W.; Shklover,
V.; Berke, H.; Nanz, D.; von Philipsborn, W. Helv. Chim. Acta 1991,
74, 1194.
(33) Shaw, W. J . Unpublished results, 1999.

N-Containing Heteroallene Addition to Fe(II)-Hydrides
Organometallics, Vol. 20, No. 16, 2001 3497
further purification. Phenyl isothiocyanate and phenyl iso-
cyanate were purchased from Fluka and were washed through
silica and deoxygenated prior to use. Ethyl isothiocyanate was
purchased from Aldrich Chemical Co. and was deoxygenated
prior to use. The syntheses of cis-Fe(dmpe)2H2 (1)38,39 and cis-
Fe(PP3)H2 (2)32 have been described elsewhere.
were collected and washed with ether to afford 3c as a dark
purple crystalline solid in analytically pure form (22 mg, 42%).
Anal. Calcd for C26H44N2P4S2Fe: C, 49.68; H, 7.06; N, 4.46.
1
Found: C, 49.9; H, 7.2; N, 4.7. H NMR (benzene-d6, 300 K):
δ 1.41 (br s, 24H, PCH3), 2.32 (br s, 8H, PCH2), 6.91 (m, 6H,
4
Phmeta + Phpara), 7.15 (m, 4H, Phortho), 8.76 (p, J PH ) 2 Hz,
2H, FeSCHNPh). 31P{1H} NMR: δ 60.3 (s). 13C{1H} NMR: δ
16.8 (p, J CP ) 7 Hz, PCH3), 31.8 (p, J CP ) 11 Hz, PCH2), 120.4
(s, Phmeta), 123.0 (s, Phpara), 129.2 (s, Phortho), 154.1 (s, Phipso),
174.2 (p, 3J CP ) 6 Hz, FeSCHNPh). IR (KBr disk, cm-1): 1593
(ν(CdN)), 2898 (ν(SCHNPh)).
1H, 31P, and 13C NMR spectra were recorded on a Bruker
DRX400 NMR spectrometer at 400.2, 162.0, and 100.6 MHz,
respectively. 1H NMR spectra were referenced to residual
toluene-d7 at δ 2.09, tetrahydrofuran-d7 at δ 3.58, or benzene-
d5 at δ 7.15; 31P NMR spectra were referenced to external neat
trimethyl phosphite at δ 140.85; and 13C NMR spectra were
referenced to tetrahydrofuran-d8 at δ 67.4 or benzene-d6 at δ
128.0. Infrared spectra were recorded on a Perkin-Elmer 1600
Series FTIR spectrometer as KBr disks. Electrospray mass
spectra were recorded on a Finnigan MAT LCQ mass spec-
trometer. High-resolution mass spectra were recorded on a
Bruker 4.7 T BioApex FTMS fitted with an analytica electro-
spray source at Monash University, Australia. Elemental
analyses were carried out at the Campbell Microanalytical
Laboratory, University of Otago, New Zealand.
(OC-6-32)-Bis(1,2-b is(d im et h ylp h osp h in o)et h a n e)h y-
drido(N-phenylthioformimidato)iron(II), tra ns-Fe(dmpe)2-
(SCHNP h )H (3a ). Phenyl isothiocyanate (11.3 mg, 0.084
mmol) in benzene-d6 (0.3 mL) was added portionwise at 300
K to an NMR tube containing a solution of cis-Fe(dmpe)2H2
(1) (30 mg, 0.084 mmol) in benzene-d6 (0.5 mL). NMR
spectroscopy indicated quantitative formation of 3a . Removal
of solvent and recrystallization of the residue from ether
afforded 3a as an orange-red solid (24 mg, 57%).
Dark brown crystals of 3c suitable for structure determi-
nation by X-ray analysis were grown by slow evaporation of a
solution of 3c in benzene-d6 at 300 K.
R ea ct ion b et w een cis-F e(d m p e)2H 2 (1) a n d E t h yl
Isoth iocya n a te. Ethyl isothiocyanate (7.3 mg, 0.084 mmol)
in benzene-d6 (0.3 mL) was added portionwise at 300 K to an
NMR tube containing a solution of cis-Fe(dmpe)2H2 (1) (30 mg,
0.084 mmol) in benzene-d6 (0.5 mL). NMR spectroscopy
indicated quantitative reaction of 1 to form two new prod-
ucts: trans-Fe(dmpe)2(SCHNEt)H (4a ) and cis-Fe(dmpe)2-
(SCHNEt)H (4b) in a 1:1.25 ratio. With heat, or on standing,
4a was formed exclusively within 3 h. Removal of solvent and
recrystallization from ether afforded 4a as a red oil which
crystallized on standing (31 mg, 84%).
(OC-6-32)-Bis(1,2-b is(d im et h ylp h osp h in o)et h a n e)h y-
dr ido(N-eth ylth iofor m im idato)ir on (II), tr a n s -Fe(dm pe)2-
(SCHNEt)H (4a ). Mp 42-45 °C. HRMS (ES) calcd for
C
15H38NP4SFe (M - 1)+: requires 444.1025, found 444.1015.
2
1H NMR (benzene-d6, 300 K): δ -25.38 (p, J PH ) 51 Hz, 1H,
3
Fe-H), 1.10 (br s, 12H, PCH3), 1.19 (t, J HH ) 8 Hz, 3H,
FeSCHNCH2CH3), 1.43 (m, 4H, PCH2), 1.54 (br s, 12H, PCH3),
Mp >220 °C (dec). HRMS (ES) calcd for C19H38NP4SFe (M
- 1)+: requires 492.1025, found 492.1042. 1H NMR (benzene-
3
2
2.25 (m, 4H, PCH2), 3.37 (q, J HH ) 8 Hz, 2H, FeSCHNCH2-
d6, 300 K) δ -24.93 (p, J PH ) 50 Hz, 1H, Fe-H), 1.05 (br s,
CH3), 9.03 (s, 1H, FeSCHNEt). 31P{1H} NMR: δ 71.3 (s).
13C{1H} NMR: δ 17.0 (m, PCH3), 18.0 (s, FeSCHNCH2CH3),
24.9 (m, PCH3), 32.4 (s, PCH2), 55.7 (s, FeSCHNCH2CH3),
172.4 (p, 3J CP ) 5 Hz, FeSCHNEt). IR (KBr disk, cm-1): 1540
(ν(CdN)), 1785 (ν(Fe-H)), 2898 (ν(SCHNEt)).
12H, PCH3), 1.40 (m, 4H, PCH2), 1.50 (br s, 12H, PCH3), 2.25
(m, 4H, PCH2), 6.92 (m, 1H, Phpara), 7.05 (m, 2H, Phmeta), 7.18
(m, 2H, Phortho) 9.49 (s, 1H, FeSCHNPh). 31P{1H} NMR: δ 70.7
(s). 13C{1H} NMR: δ 17.0 (br s, PCH3), 24.8 (br s, PCH3), 32.4
(s, PCH2), 120.5 (s, Phmeta), 122.0 (s, Phpara), 129.1 (s, Phortho),
155.4 (s, Phipso), 177.8 (s, FeSCHNPh). IR (KBr disk, cm-1):
1590 (ν(CdN)), 1789 (ν(Fe-H)), 2900 (ν(SCHNPh)).
(OC-6-24)-Bis(1,2-b is(d im et h ylp h osp h in o)et h a n e)h y-
d r id o(N-eth ylth iofor m im id a to)ir on (II), cis-F e(d m p e)2-
(SCHNE t )H (4b). 1H NMR (benzene-d6, 300 K): δ -11.33
Rea ction betw een cis-F e(d m p e)2H2 (1) a n d P h en yl
Isot h iocya n a t e a t Low er Tem p er a t u r e. Phenyl isothio-
cyanate (11.3 mg, 0.084 mmol) in tetrahydrofuran-d8 (0.3 mL)
was added portionwise at 250 K to an NMR tube containing a
solution of cis-Fe(dmpe)2H2 (1) (30 mg, 0.084 mmol) in tetra-
hydrofuran-d8 (0.5 mL). NMR spectroscopy indicated the
formation of five products in varying amounts, including trans-
Fe(dmpe)2(SCHNPh)H (3a ) (approximately 80%) and cis-
Fe(dmpe)2(SCHNPh)H (3b). Upon warming to 280 K, only 3a
and 3b remained in solution, and further warming to 300 K
resulted in quantitative formation of 3a .
2
(ddt, J PH ) 65, 55, 32 Hz, 1H, Fe-H), 0.68 (m), 0.91 (m), 1.00
(m), 1.19 (t, 3J HH ) 8 Hz, 3H, FeSCHNCH2CH3), 1.30 (m), 1.49
3
(m), 3.57 (q, J HH ) 8 Hz, 2H, FeSCHNCH2CH3), 8.71 (s, 1H,
FeSCHNEt). 31P{1H} NMR: δ 54.9 (m), 66.5 (ddd, J ) 150,
41, 22 Hz), 71.0 (ddd, J ) 150, 41, 32), 73.12 (m). 13C{1H}
NMR: δ 15.0-20.0 (m), 18.0 (s, FeSCHNCH2CH3), 20.6 (m),
29.4 (m), 33.3 (m), 56.4 (s, FeSCHNCH2CH3), 181.7 (s, Fe-
SCHNEt).
tr a n s-F e(d m p e)2(SCHN+(Et)C(S)N-(Et))H (4c). Ethyl
isothiocyanate (7.3 mg, 0.084 mmol, 1 equiv) in benzene-d6 (0.3
mL) was added at 300 K to an NMR tube containing a solution
of trans-Fe(dmpe)2(SCHNEt)H (4a ) in benzene-d6 (0.5 mL)
which had been prepared in situ by the reaction between cis-
Fe(dmpe)2H2 (1) (30 mg, 0.084 mmol) and EtNCS (7.3 mg,
0.084 mmol). The reaction mixture was allowed to stand
overnight. NMR spectroscopy indicated quantitative reaction
of 1 to form trans-Fe(dmpe)2(SC(H)N+(Et)C(S)N-(Et))H (4c)
and some minor reaction byproducts. Concentration of the
solution afforded 4c as a red crystalline solid which was
washed with ether but was not obtained analytically pure (10
mg, 22%).
(OC-6-24)-Bis(1,2-b is(d im et h ylp h osp h in o)et h a n e)h y-
d r id o(N-p h en ylth iofor m im id a to)ir on (II), cis-F e(d m p e)2-
(SCHNP h )H (3b). 1H NMR (tetrahydrofuran-d8, 260 K): δ
2
-11.46 (ddt, J PH ) 64, 54, 31 Hz, 1H, Fe-H), 8.71 (s, 1H,
FeSCHNPh). 31P{1H} NMR: δ 56.2 (dt, J ) 32, 21 Hz), 67.6
(ddd, J ) 141, 41, 21 Hz), 72.6 (ddd, J ) 141, 41, 32 Hz), 74.6
(dt, J ) 41, 21 Hz).
(OC-6-12)-Bis(1,2-bis(d im eth ylp h osp h in o)eth a n e)bis-
(N-p h en ylt h iofor m im id a t o)ir on (II), tr a n s-F e(d m p e)2-
(SCHNP h )2 (3c). Phenyl isothiocyanate (23 mg, 0.17 mmol)
in benzene-d6 (0.5 mL) was added portionwise at 300 K to an
NMR tube containing a solution of cis-Fe(dmpe)2H2 (1) (30 mg,
0.084 mmol) in benzene-d6 (0.5 mL). NMR spectroscopy
indicated quantitative formation of 3c after 3 h. Concentration
of the solvent precipitated dark purple crystals of 3c which
HRMS (ES) calcd for C18H45N2P4S2Fe (M + 1)+: requires
533.1324, found 533.1299. 1H NMR (benzene-d6, 300 K): δ
2
-24.47 (p, J PH ) 50 Hz, 1H, Fe-H), 0.98 (br s, 12H, PCH3),
3
1.26 (br s, 12H, PCH3), 1.29 (t, J HH ) 7 Hz, 3H, FeSCHN+-
3
CH2CH3), 1.35 (m, 4H, PCH2), 1.60 (t, J HH ) 7 Hz, 3H,
FeSCHN+(Et)C(S)N-CH2CH3), 1.85 (m, 4H, PCH2), 4.23 (q,
(38) Chatt, J .; Hayter, R. G. J . Chem. Soc. 1961, 5507.
(39) Whittlesey, M. K.; Mawby, R. J .; Osman, R.; Perutz, R. N.; Field,
L. D.; Wilkinson, M. P.; George, M. W. J . Am. Chem. Soc. 1993, 115,
8627.
3
3J HH ) 7 Hz, 2H, FeSCHN+(Et)C(S)N-CH2CH3), 4.69 (q, J HH
) 7 Hz, 2H, FeSCHN+CH2CH3) 11.06 (s, 1H, FeSCHN).
31P{1H}NMR: δ68.5 (s). 13C{1H}NMR: δ12.8 (s, FeSCHN+(Et)-

3498 Organometallics, Vol. 20, No. 16, 2001
Field et al.
C(S)N-CH2CH3), 15.5 (m, PCH3), 16.9 (s, FeSCHN+CH2CH3),
24.0 (m, PCH3), 31.6 (s, PCH2), 40.4 (s, FeSCHN+(Et)C(S)-
N-CH2CH3), 49.5 (s, FeSCHN+CH2CH3), 169.8 (s, FeSCHN),
193.5 (s, FeSCHN+(Et)C(S)). IR (KBr disk, cm-1): 984, 1225
(ν(CdS)), 1551 (ν(CdN)), 1811 (ν(Fe-H)), 2900 (ν(FeSCHN)).
Red crystals of 4c suitable for structure determination by
X-ray analysis were grown at 300 K by slow evaporation of a
solution of 4c in benzene-d6.
R ea ct ion b et w een cis-F e(d m p e)2H 2 (1) a n d P h en yl
Isocya n a te. Phenyl isocyanate (18 mg, 0.15 mmol) in benzene-
d6 (0.5 mL) was added portionwise at 300 K to an NMR tube
containing a solution of cis-Fe(dmpe)2H2 (1) (30 mg, 0.084
mmol) in benzene-d6 (0.5 mL). NMR spectroscopy indicated
quantitative reaction of 1 to form trans-Fe(dmpe)2(OCHNPh)H
(5a ) and four other products, as well as a red oily precipitate.
Filtration, removal of solvent, and recrystallization from ether
afforded 5a as a red solid which could not be separated from
other soluble reaction products.
1)+: requires 625.1011, found 625.1011. 1H NMR (tetrahydro-
furan-d8, 300 K): δ 0.48-2.65 (m, 30H, PA(CH2CH2P(CH3)2),
6.80-7.40 (m, 10H, Ph), 9.26 (s, 1H, FeSCHNPh(trans to PA)),
9.63 (s, 1H, FeSCHNPh(trans to PE)). 31P{1H} NMR: δ 178.4
(dt (apparent q), J ) 23 Hz, 1P, PA), 73.3 (dt, J P
) 42 Hz,
P
E
T
J P A ) 23 Hz, 1P, PE), 53.6 (dd, J P
) 42 Hz, J P A ) 23 Hz,
P
P
P
E
T
E
T
2P, PT). 13C{1H} NMR: δ 15.8 (m), 20.7 (m), 21.6 (br s), 26.7
(m), 30.1 (m), 32.5 (m), 35.2 (m) (PA(CH2CH2P(CH3)2), 120.8,
120.6, 122.7, 123.2, 127.0, 131.5, 152.3, 155.4 (Ph), 176.8 (m,
FeSCHNPh(trans to PA)), 176.4 (m, FeSCHNPh(trans to PE)).
IR (KBr disk, cm-1): 1590 (ν(CdN)), 2903 (ν(SCHNPh)).
(OC-6-24)-Hyd r id o(N-eth ylth iofor m im id a to)(tr is(2-d i-
m eth ylp h osp h in oeth yl)p h osp h in e)ir on (II), cis-F e(P P 3)-
(SCHNEt)H (7a ). Ethyl isothiocyanate (5 mg, 0.058 mmol)
in benzene-d6 (0.2 mL) was added portionwise at 300 K to an
NMR tube containing a solution of cis-Fe(PP3)H2 (2) (20 mg,
0.058 mmol) in benzene-d6 (0.5 mL). NMR spectroscopy
indicated quantitative formation of 7a . Removal of solvent and
recrystallization from ether afforded 7a as a bright yellow solid
(17 mg, 65%).
(OC-6-32)-Bis(1,2-b is(d im e t h ylp h osp h in o)e t h a n e )-
h yd r id o(N-p h en ylfor m im id a to)ir on (II), cis-F e(d m p e)2-
(OCHNP h )H (5a ). 1H NMR (benzene-d6, 300 K): δ -34.31
Mp 185 °C (dec). HRMS (ES) calcd for C15H36NP4SFe (M -
1)+: requires 442.0868, found 442.0886. 1H NMR (benzene-
2
(p, J PH ) 49 Hz, 1H, Fe-H), 1.07 (br s, 12H, PCH3), 1.39 (br
d6, 300 K) δ -13.92 (ddt, J P ) 66 Hz, J P ) 41 Hz, J P
)
s, 12H, PCH3), 1.47 (m, 4H, PCH2), 2.15 (m, 4H, PCH2), 6.92
(m, 1H, Phpara), 7.02 (m, 2H, Phmeta), 7.26 (m, 2H, Phortho), 8.13
(s, 1H, FeOCHNPh). 31P{1H} NMR: δ 70.7 (s). 13C{1H} NMR:
δ 15.4 (br s, PCH3), 23.0 (br s, PCH3), 31.7 (s, PCH2), 120.0 (s,
Phmeta), 121.6 (s, Phpara), 129.0 (s, Phortho), 148.7 (s, Phipso), 167.8
(s, FeOCHNPh). IR (KBr disk, cm-1): 1595 (ν(CdN)), 1792
(ν(Fe-H)), 2903 (ν(OCHNPh)). MS m/z (ES): 476 (M - 1)+,
595 (M + PhNCO - 1)+.
H
H
H
E
T
A
34 Hz, 1H, Fe-H), 0.95-1.16 (m, 12H, PA(CH2CH2P(CH3)2),
1.10 (t, 3J HH ) 7 Hz, 3H, FeSCHNCH2CH3), 1.29, 1.59 (2 × m,
3
2 × 6H, 2 × PT(CH3)), 1.43 (m, 6H, PE(CH3)2), 3.56 (q, J HH
)
7 Hz, 2H, FeSCHNCH2CH3), 9.31 (br s, 1H, FeSCHNEt).
31P{1H} NMR: δ 181.0 (dt, J P
) 30 Hz, J P
E
) 24 Hz, 1P,
P
P
E
A
T
A
PA), 62.8 (dd, J P A ) 30 Hz, J P
) 24 Hz, 2P, PT), 61.2 (q, J
P
P
T
T
) 24 Hz, 1P, PE). 13C{1H} NMR: δ 18.2 (s, FeSCHNCH2CH3),
19.3 (m), 20.7 (m), 25.0 (m), 27.4 (m), 30.2 (s), 35.5 (m), 36.3
(m) (PA(CH2CH2P(CH3)2)3), 55.8 (s, FeSCHNCH2CH3), 173.6
(m, FeSCHNEt). IR (KBr disk, cm-1): 1543 (ν(CdN)), 1803
(ν(Fe-H)), 2898 (ν(SCHNEt)).
(OC-6-24)-Hyd r id o(N-p h en ylth iofor m im id a to)(tr is(2-
dim eth ylph osph in oeth yl)ph osph in e)ir on (II), cis-Fe(P P 3)-
(SCHNP h )H (6a ). Phenyl isothiocyanate (7.8 mg, 0.058 mmol)
in benzene-d6 (0.3 mL) was added portionwise at 300 K to an
NMR tube containing a solution of cis-Fe(PP3)H2 (2) (20 mg,
0.058 mmol) in benzene-d6 (0.5 mL). NMR spectroscopy
indicated quantitative formation of 6a . Removal of solvent and
recrystallization from ether afforded 6a as a yellow solid (16
mg, 57%).
(OC-6-24)-H yd r id o(N-p h en ylfor m im id a t o)(t r is(2-d i-
m eth ylp h osp h in oeth yl)p h osp h in e)ir on (II), cis-F e(P P 3)-
(OCHNP h )H (8a ). Phenyl isocyanate (7 mg, 0.058 mmol) in
benzene-d6 (0.3 mL) was added portionwise at 300 K to an
NMR tube containing a solution of cis-Fe(PP3)H2 (2) (20 mg,
0.058 mmol) in benzene-d6 (0.5 mL). NMR spectroscopy
indicated essentially quantitative formation of 8a . Removal
of solvent and recrystallization from ether afforded 8a as a
bright yellow solid which was not further purified (14 mg,
50%).
Mp 200-205 °C (dec). HRMS (ES) calcd for C19H36NP4SFe
(M - 1)+: requires 490.0868, found 490.0838. 1H NMR
(benzene-d6, 300 K): δ -14.05 (ddt, J PTH ) 66 Hz, J PAH ) 42
Hz, J PEH ) 33 Hz, 1H, Fe-H), 0.90-1.15 (m, 12H, PA(CH2CH2P-
(CH3)2), 1.28, 1.57 (2 × m, 2 × 6H, 2 × PT(CH3)), 1.42 (m, 6H,
PE(CH3)2), 6.95 (m, 1H, Phpara), 7.15 (m, 2H, Phmeta), 7.23 (m,
Mp 210 °C (dec). 1H NMR (benzene-d6, 300 K): δ -13.07
(m, 1H, Fe-H), 0.90-1.48 (m, 12H, PA(CH2CH2P(CH3)2), 1.09,
1.56 (2 × br s, 2 × 6H, 2 × PT(CH3)), 1.46 (s, 6H, PE(CH3)2),
6.94 (m, 1H, Phpara), 7.11-7.23 (m, 4H, Phortho + Phmeta) 8.81
4
2H, Phortho), 9.70 (p, J PH ) 2.5 Hz, 1H, FeSCHNPh). 31P{1H}
NMR: δ 180.4 (dt, J PAPT ) 30 Hz, J PAPE ) 22 Hz, 1P, PA), 62.8
(dd, J P A ) 30 Hz, J P
) 22 Hz, 2P, PT), 60.8 (q, J ) 22 Hz,
P
P
T
T
E
(s, 1H, FeOCHNPh). 31P{1H} NMR: δ 173.3 (dt, J P
) 33
) 23
1P, PE). 13C{1H} NMR: δ 19.3 (m), 20.7 (m), 24.9 (m), 27.3
(m), 30.2 (s), 35.4 (m), 36.3 (m) (PA(CH2CH2P(CH3)2)3), 120.8
(Phmeta), 121.8 (Phpara), 129.1 (Phortho), 156.3 (Phipso), 178.7 (m,
FeSCHNPh). IR (KBr disk, cm-1): 1494 (ν(CdN)), 1802 (ν(Fe-
H)), 2897 (ν(SCHNPh)).
P
A
T
Hz, J P
) 23 Hz, 1P, PA), 56.2 (dd, J P A ) 33 Hz, J P
P
A
P
P
T E
E
T
Hz, 2P, PT), 55.1 (q, J ) 23 Hz, 1P, PE). 13C{1H} NMR: δ 19.7
(m), 20.5 (m), 25.3 (m), 27.9 (m), 30.2 (s), 35.6 (q, J ) 16 Hz),
36.9 (dd, J ) 16, 25 Hz) (PA(CH2CH2P(CH3)2)3), 55.8 (s,
FeSCHNCH2CH3), 122.1 (Phmeta + Phpara), 128.7 (Phortho), 160.6
(Phipso), 170.3 (m, FeOCHNPh). IR (KBr disk, cm-1): 1571
(ν(CdN)), 1794 (ν(Fe-H)), 2900 (ν(OCHNPh)). MS m/z (ES):
474 (M - 1)+.
Rea ction betw een cis-F e(P P 3)(SCHNP h )H (6a ) a n d
Excess P h en yl Isoth iocya n a te. Phenyl isothiocyanate (7.8
mg, 0.058 mmol) in benzene-d6 (0.3 mL) was added at 300 K
to an NMR tube containing a solution of cis-Fe(PP3)(SCHNPh)H
(6a ) in benzene-d6 (0.5 mL) which had been prepared in situ
by the reaction between cis-Fe(PP3)H2 (2) (20 mg, 0.058 mmol)
and phenyl isothiocyanate (7.8 mg, 0.058 mmol). Over 7 h, 6a
reacted until no 31P-containing material was left in solution.
Large amounts of a cream-colored precipitate were formed. The
precipitate was collected and washed with ether to afford a
cream solid which was only slightly soluble in tetrahydrofuran,
forming a red solution. 31P NMR showed the presence of two
products in the ratio 2.5:1, and the major product was assigned
as cis-Fe(PP3)(SCHNPh)2 (6b). The minor product was not
further characterized.
X-r a y Mea su r em en ts for tr a n s-F e(d m p e)2(SCHNP h )2
(3c) a n d tr a n s-F e(d m p e)2(SC(H)N+(Et)C(S)N-(Et))H (4c).
A summary of crystal data for 3c and 4c is given in Table 4.
tr a n s-F e(d m p e)2(SCHNP h )2 (3c). A dark brown bladelike
crystal was attached, with Exxon Paratone N, to a short length
of fiber supported on a thin piece of copper wire inserted in a
copper mounting pin and was quenched in a cold nitrogen gas
stream upon mounting on a Bruker SMART 1000 diffrac-
tometer equipped with an Oxford Cryosystems Cryostream.
Graphite-monochromated Mo KR radiation was generated
from a sealed tube. Cell constants were obtained from a least
squares refinement against 916 reflections located in the range
5.15 < 2θ < 56.29°. Data were collected at 173(1) K with ω
scans to 2θ ) 56.62°. The intensities of 189 standard reflections
(OC-6-23)-Bis(N -p h e n ylt h iofor m im id a t o)(t r is(2-d i-
m eth ylp h osp h in oeth yl)p h osp h in e)ir on (II), cis-F e(P P 3)-
(SCHNP h )2 (6b). HRMS (ES) calcd for C26H41N2P4S2Fe (M -

N-Containing Heteroallene Addition to Fe(II)-Hydrides
Organometallics, Vol. 20, No. 16, 2001 3499
recollected at the end of the experiment did not change
significantly during the data collection. An empirical correc-
tion, determined with SADABS,40 was applied to the data. The
data integration and reduction were undertaken with SAINT
and XPREP,41 and subsequent computations were carried out
with the teXsan42 graphical user interface. The data reduction
included the application of Lorentz and polarization correc-
tions. The structure was solved in the space group P21/c (No.
14) by direct methods with SIR9743 and extended and refined
with SHELXL-97.44 The molecule is centered on an inversion
site. Most of the non-hydrogen atoms were modeled with
anisotropic thermal parameters, and a riding atom model was
used for the hydrogen atoms included in the model. The ligand
backbone adopted at least two orientations, and the popula-
tions of the disordered backbone C(3) and C(4) sites were
initially refined and then fixed at 0.5. The disordered atoms
were modeled with isotropic temperature factors.
tr a n s-F e(d m p e)2(SC(H)N+(Et)C(S)N-(Et))H (4c). A red
prismatic crystal was inserted in a glass capillary before
mounting on a Bruker SMART 1000 CCD. Graphite-mono-
chromated Mo KR radiation was generated from a sealed tube.
Cell constants were obtained from a least squares refinement
against 929 reflections located in the range 4.47 < 2θ < 51.02°.
Data were collected at 294(2) K with ω scans to 2θ ) 56.74°.
The data integration and reduction were undertaken with
SAINT and XPREP,41 and subsequent computations were
carried out with the teXsan42 graphical user interface. The
data reduction included the application of Lorentz and polar-
ization correctionsand a Gaussian absorption correction. The
structure was solved in the space group P1h (No. 2) by direct
methods with SIR9743 and extended and refined with SHELXL-
97.44 The asymmetric unit contained a complex molecule and
a highly disordered solvate region. The non-hydrogen atoms
of the complex molecule were modeled with anisotropic
thermal parameters, and a riding atom model was used for
the hydrogen atoms, with the exception of the hydride, which
was located and modeled with an isotropic thermal parameter.
The disordered solvate molecule region could not be clearly
resolved, but is confined to a plane and suggests almost
continuous rotational disorder about an axis perpendicular to
the solvate molecule plane. Individual solvate molecules could
not be discerned. The solvate molecules were assumed to be
benzene in at least two overlapping locations, and 12 carbon
atoms were assigned to the region with occupancies fixed at
0.25%, i.e., two complex molecules for every benzene molecule.
No hydrogen atoms were included in the model for the solvate
molecule.
Ack n ow led gm en t. We gratefully acknowledge fi-
nancial support from the Australian Research Council
and the Australian Commonwealth Government for an
Australian Postgraduate Award to W.J .S.
(40) (a) Blessing, R. H. Acta Crystallogr. 1995, A51, 33. (b) Sheldrick,
G. M. SADABS: Empirical absorption correction program for area
detector data; University of Go¨ttingen: Go¨ttingen, Germany, 1996.
(41) SMART, SAINT, and XPREP: Area detector control and data
integration and reduction software; Bruker Analytical X-ray Instru-
ments Inc.: Madison, WI, 1995.
(42) teXsan for Windows: Single-Crystal Structure Analysis Soft-
ware; Molecular Structure Corp.: The Woodlands, TX, 1997-1998.
(43) Altomare, A.; Cascarano, M.; Giacovazzo, C.; Guagliardi, A. J .
Appl. Crystallogr. 1993, 26, 343.
Su p p or tin g In for m a tion Ava ila ble: X-ray crystallo-
graphic data files, in CIF format, for trans-Fe(dmpe)2-
(SCHNPh)2 (3c) and trans-Fe(dmpe)2(SC(H)N+(Et)C(S)-
N-(Et))H (4c) and 31P NMR spectra of selected compounds.
This material is available free of charge via the Internet at
http://pubs.acs.org.
(44) Sheldrick, G. M. SHELXL-97: Program for crystal structure
refinement; University of Go¨ttingen, Go¨ttingen, Germany, 1997.
OM0100030