Insertion of heteroallenes into the rhenium-hydride bond

Article abstract of DOI:10.1016/j.ica.2005.04.026

Dithioformato [Re{η²-SC(H)S}(NO)P₃]BPh ₄ (1), thioformamido [Re{η²-RNC(H)S}(NO)P ₃]BPh₄ (2) (R = Et, p-tolyl), formamido [Re{η²-PhNC(H)O}(NO)P₃]BPh₄ (3) and

Full text of DOI:10.1016/j.ica.2005.04.026

Inorganica Chimica Acta 358 (2005) 3093–3105
www.elsevier.com/locate/ica
Insertion of heteroallenes into the rhenium–hydride bond
*
Gabriele Albertin , Stefano Antoniutti, Giovanni Roveda
`
Dipartimento di Chimica, Universita CaÕ Foscari di Venezia, Dorsoduro, 2137, 30123 Venezia, Italy
Received 13 December 2004; received in revised form 29 March 2005; accepted 22 April 2005
Abstract
Dithioformato [Re{g2-SC(H)S}(NO)P3]BPh4 (1), thioformamido [Re{g2-RNC(H)S}(NO)P3]BPh4 (2) (R = Et, p-tolyl), form-
amido [Re{g2-PhNC(H)O}(NO)P3]BPh4 (3) and formamidinato [Re{g2-p-tolylNC(H)Np-tolyl}(NO)P3]BPh4 (4) (P = PPh2OEt)
complexes were prepared by allowing the hydride ReH2(NO)P3 to react first with triflic acid and then with the appropriate hetero-
allene CS2, RNCS, PhNCO and p-tolylNCNp-tolyl. Treatment of the ReH2(NO)L(PPh3)2 [L = P(OEt)3, PPh(OEt)2] and ReH2(NO)
(PPh3)3 hydrides first with triflic acid and then with isothiocyanate RNCS (R = Et, p-tolyl) gave the [Re{g2-RNC(H)S}(NO)
{P(OEt)3}(PPh3)2]BPh4 (5, 6) and [Re(g2-RNC(H)S)(NO)(PPh3)3]BPh4 (7) derivatives. Depending on the nature of the phosphite,
instead, the reaction of ReH2(NO)L(PPh3)2 and ReH2(NO)(PPh3)3 hydrides first with CF3SO3H and then with isocyanate
R1NCO (R1 = Ph, p-tolyl) gave the chelate [Re{g2-R1NC(H)O}(NO){P(OEt)3}(PPh3)2]BPh4 (8) and [Re{g2-R1NC(H)O}
(NO)(PPh3)3]BPh4 (10) complexes with P(OEt)3 or PPh3, while the g1-coordinate [Re{g1-RNC(H)S}(NO){PPh(OEt)2}2(PPh3)2]BPh4
(9) derivative was obtained with the PPh(OEt)2 phosphite ligand. g1-Coordinate dithioformato [Re{g1-SC(H)@S}(NO)
{PPh(OEt)2}2(PPh3)2]BPh4 (11) and formato [Re{g1-OC(H)@O}(NO){PPh(OEt)2}2(PPh3)2]BPh4 (12) complexes, as well as the
formamidinato [Re{g2-p-tolylNC(H)Np-tolyl}(NO){P(OEt)3}(PPh3)2]BPh4 (13) derivative were also prepared.
Ó 2005 Elsevier B.V. All rights reserved.
Keywords: Formamido; Thioformamido; Formato; Dithioformato; Heteroallenes; Hydride; P ligands; Rhenium
1. Introduction
cules into the M À H bond have been reported giving
formato, thioformato, formamido, thioformamido,
and formamidinato derivatives bonded to the metal
either in g1- or g2-fashion [2,3,6].
Not only does the iron triad play a prominent role
among the metal centers involved in these reactions,
but ruthenium complexes have also recently been re-
ported to catalyze the hydrogenation of carbon dioxide
to formic acid [4]. In contrast, few studies have been re-
ported on the manganese triad [3b,5] and on the rhe-
nium as a central metal [5].
We are interested in the synthesis and reactivity of
transition metal hydrides [7] and have previously re-
ported on the reactivity with heteroallenes of hydride
complexes of the iron triad of the [MH(g2-H2)P4]+
(M = Fe, Ru, Os; P = phosphite) type, which led to the
synthesis of dithioformato, formamido and formamidi-
nato derivatives [6]. Now we have extended these studies
The insertion of heteroallenes such as CO2, CS2,
RNCO, and RNCS into the metal–hydride bond is an
important chemical step in functionalizing these mole-
cules [1–6]. CO2 has drawn the most attention due to
its potential usefulness as a C1 building block in con-
structing higher organic structures [1a,4]. However, the
reaction of other heteroallenes has also been extensively
studied not only as a model for CO2 but also because the
isocyanate or isothiocyanate functionality is useful as a
source of carbon, nitrogen, and oxygen or sulfur in
one chemical step [1–3]. Thus, a number of studies on
the insertion reaction of these small unsaturated mole-
*
Corresponding author. Tel.: +39 041 234 8555; fax: +39 041 234
8917.
E-mail address: albertin@unive.it (G. Albertin).
0020-1693/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2005.04.026

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G. Albertin et al. / Inorganica Chimica Acta 358 (2005) 3093–3105
to include rhenium as a central metal and in this paper
we report some studies on the insertion reaction of car-
bon disulfide, carbon dioxide, N-substituted isocyanate
and isothiocyanate, and carbodiimide into the Re(I)-hy-
dride bonds of rhenium phosphite derivatives.
À30 °C, stirred for about 1 h and then an excess of
CS2 (0.38 mmol, 23 lL) was added. The solution was al-
lowed to reach the room temperature, stirred for about
6 h and then the solvent was removed under reduced
pressure. The oil obtained was treated with ethanol con-
taining an excess of NaBPh4 (0.22 mmol, 75 mg) in 1 mL
of ethanol. A yellow-orange solid slowly separated out
which was collected by filtration and crystallized from
CH2Cl2 and ethanol; Yield: P65%. Calc. for
C67H66BNO4P3ReS2 (1303.31): C, 61.75; H, 5.10; N,
1.07; S, 4.92. Found: C, 61.58; H, 5.03; N, 1.15; S,
4.75%. KM = 51.4 XÀ1 molÀ1 cm2.
2. Experimental
2.1. General considerations
All synthetic work was carried out under an inert
atmosphere using standard Schlenk techniques or a Vac-
uum Atmosphere dry-box. Once isolated, the complexes
were found to be relatively stable in air, but were stored
under an inert atmosphere at À25 °C. All solvents were
dried over appropriate drying agents, degassed on a vac-
uum line and distilled into vacuum-tight storage flasks.
The phosphites PPh(OEt)2 and PPh2OEt were prepared
by the method of Rabinowitz and Pellon [8], whereas
P(OEt)3 was an Aldrich product, purified by distillation
under nitrogen. The heteroallenes CS2, p-tolylNCS,
EtNCS, PhNCO, p-tolylNCO, and p-tolylNCNp-tolyl
were Aldrich products used without any further purifi-
cation. Other reagents were purchased from commercial
sources (Aldrich, Fluka) in the highest available purity
and used as received. Infrared spectra were recorded
on a Nicolet Magna 750 FT-IR spectrophotometer.
NMR spectra (1H, 13C, 31P) were obtained on Bruker
AC200 or AVANCE 300 spectrometers at temperatures
varying between À90 and +30 °C, unless otherwise
2.2.2. [Re{g2-RNC(H)S}(NO)(PPh2OEt)3]BPh4 (2)
[R = Et (a), p-tolyl (b)]
An equimolar amount of CF3SO3H (0.11 mmol,
10 lL) was added to a solution of ReH2(NO)(PPh2-
OEt)3 (100 mg, 0.11 mmol) in 10 mL of CH2Cl2 cooled
to À196 °C. The reaction mixture was brought to
À30 °C, stirred for about 1 h and then an excess of the
appropriate isothiocyanate RNCS (1.7 mmol) was
added. The solution was allowed to reach the room tem-
perature and then stirred for about 7 h. The solvent was
removed under reduced pressure to give an oil which
was treated with ethanol containing an excess of
NaBPh4 (0.22 mmol, 75 mg) in 1 mL of ethanol. A yel-
low solid slowly separated out which was collected by
filtration and crystallized from CH2Cl2 and ethanol. A
typical crystallization involved the slow cooling to
À25 °C of a solution of the complex prepared by adding
5 mL of ethanol and enough CH2Cl2 to obtain a satu-
rated solution at room temperature; Yield: P65%.
2a: Calc. for C69H71BN2O4P3ReS (1314.32): C, 63.06;
H, 5.44; N, 2.13; S, 2.44. Found: C, 62.85; H, 5.60; N,
2.15; S, 2.31%. KM = 50.8 XÀ1 molÀ1 cm2.
1
noted. H and 13C spectra are referred to internal tetra-
methylsilane, while 31P{1H} chemical shifts are reported
with respect to 85% H3PO4, with downfield shifts con-
sidered positive. The COSY, HMQC and HMBC
NMR experiments were performed using their standard
programs. The SWAN-MR software package [9] was used
to treat NMR data. The conductivities of 10À3 M solu-
tions of the complexes in CH3NO2 at 25 °C were mea-
2b: Calc. for C74H73BN2O4P3ReS (1376.39): C, 64.58;
H, 5.35; N, 2.04; S, 2.33. Found: C, 64.39; H, 5.42; N,
2.10; S, 2.16%. KM = 54.6 XÀ1 molÀ1 cm2.
sured with
a
Radiometer CDM 83 instrument.
2.2.3. [Re{g2-PhNC(H)O}(NO)(PPh2OEt)3]BPh4
(3)
This complex has been prepared following the meth-
od used for the related isothiocyanate complexes 2;
Yield: P45%. Calc. for C73H71BN2O5P3Re (1346.31):
C, 65.13; H, 5.32; N, 2.08. Found: C, 64.90; H, 5.40;
N, 2.07%. KM = 56.5 XÀ1 molÀ1 cm2.
Elemental analyses were determinated in the Microana-
lytical Laboratory of the Dipartimento di Scienze Far-
maceutiche of the University of Padova (Italy).
2.2. Synthesis of complexes
The ReH2(NO)(PPh2OEt)3, ReH2(NO)L(PPh3)2 [L =
P(OEt)3 and PPh(OEt)2] and ReH2(NO)(PPh3)3
hydrides were prepared following the methods previ-
ously reported [7f,10,11].
2.2.4. [Re{g2-p-tolyl-NC(H)N-p-tolyl}(NO)-
(PPh2OEt)3]BPh4 (4)
In a 25-mL three-necked round-bottomed flask,
150 mg (0.17 mmol) of ReH2(NO)(PPh2OEt)3, 250 mg
(1.12 mmol) of 1,3-di-p-tolylcarbodiimide and 10 mL of
CH2Cl2 were placed. The flask was cooled to À196 °C
and triflic acid (0.17 mmol, 15 lL) was added. The reac-
tion mixture was brought to 0 °C and stirred for 12 h.
The solvent was removed under reduced pressure to give
2.2.1. [Re{g2-SC(H)S}(NO)(PPh2OEt)3]BPh4 (1)
An equimolar amount of CF3SO3H (0.11 mmol,
10 lL) was added to a solution of ReH2(NO)(PPh2-
OEt)3 (100 mg, 0.11 mmol) in 10 mL of CH2Cl2 cooled
to À196 °C. The reaction mixture was brought to

G. Albertin et al. / Inorganica Chimica Acta 358 (2005) 3093–3105
3095
an oil which was treated with ethanol containing an ex-
cess of NaBPh4 (0.24 mmol, 82 mg). A yellow-orange so-
lid slowly separated out which was collected by filtration
and crystallized from CH2Cl2 and ethanol; Yield: P
65%. Calc. for C81H80BN3O4P3Re (1449.47): C, 67.12;
H, 5.56; N, 2.90. Found: C, 67.39; H, 5.64; N, 2.84%.
8c: Calc. for C73H71BN2O5P3Re (1346.31): C, 65.13;
H, 5.32; N, 2.08. Found: C, 64.87; H, 5.41; N, 2.01%.
K
M = 51.8 XÀ1 molÀ1 cm2.
10: Calc. for C86H73BN2O2P3Re (1456.47): C, 70.92;
H, 5.05; N, 1.92. Found: C, 71.13; H, 5.16; N, 2.04%.
M = 53.4 XÀ1 molÀ1 cm2.
K
K
M = 53.3 XÀ1 molÀ1 cm2.
2.2.8. [Re{g1-RNC(H)O}(NO){PPh(OEt)2}2-
(PPh3)2]BPh4 (9) [R = p-tolyl (b), Ph (c)]
2.2.5. [Re{g2-RNC(H)S}(NO)L(PPh3)2]BPh4 (5, 6)
[L = P(OEt)3 (5), PPh(OEt)2 (6); R = Et (a), p-tolyl
(b)]
An equimolar amount of CF3SO3H (0.1 mmol,
9 lL) was added to a solution of ReH2(NO)[P-
Ph(OEt)2](PPh3)2 (0.1 mmol, 94 mg) in 10 mL of
CH2Cl2 cooled to À196 °C. The reaction mixture
was brought to room temperature, stirred for 30 min
and then cooled again to À196 °C. An excess of the
appropriate isocyanate RNCO (0.5 mmol) was added
and the resulting solution stirred for about 4 h. The
solvent was removed under reduced pressure giving
an oil which was treated with ethanol containing an
excess of NaBPh4 (0.32 mmol, 110 mg). A yellow solid
slowly separated out which was collected by filtration
and crystallized from CH2Cl2 and ethanol; Yield:
P40%.
An equimolar amount of CF3SO3H (0.1 mmol,
9 lL) was added to a solution of the appropriate hy-
dride ReH2(NO)L(PPh3)2 (0.1 mmol) in 7 mL of
CH2Cl2 cooled to À196 °C. The reaction mixture was
brought to room temperature, stirred for 30 min and
then cooled again to À196 °C. An excess of the appro-
priate isothiocyanate RNCS (0.5 mmol) was added and
the solution, brought to room temperature, stirred for
about 4 h. The solvent was removed under reduced
pressure to give an oil which was treated with ethanol
containing an excess of NaBPh4 (0.32 mmol, 110 mg).
A yellow solid slowly separated out which was col-
lected by filtration and crystallized from CH2Cl2 and
ethanol; Yield: P65%.
5a: Calc. for C69H71BN2O4P3ReS (1314.32): C, 63.06;
H, 5.44; N, 2.13; S, 2.44. Found: C, 62.88; H, 5.52; N,
2.18; S, 2.30%. KM = 53.7 XÀ1 molÀ1 cm2.
5b: Calc. for C74H73BN2O4P3ReS (1376.39): C, 64.58;
H, 5.35; N, 2.04; S, 2.33. Found: C, 64.40; H, 5.46; N,
2.12; S, 2.27%. KM = 55.1 XÀ1 molÀ1 cm2.
9b: Calc. for C88H88BN2O6P4Re (1590.58): C, 66.45;
H, 5.58; N, 1.76. Found: C, 66.23; H, 5.66; N, 1.89%.
K
M = 54.7 XÀ1 molÀ1 cm2.
9c: Calc. for C87H86BN2O6P4Re (1576.55): C, 66.28;
H, 5.50; N, 1.78. Found: C, 66.04; H, 5.64; N, 1.90%.
K
M = 55.2 XÀ1 molÀ1 cm2.
2.2.9. [Re{g1-SC(H)S}(NO){PPh(OEt)2}2(PPh3)2]-
BPh4 (11)
This compound was prepared following the
method used for the related formamido complexes 9b
and 9c using CS2 as a reagent with a reaction time
of 6 h; Yield: P45%. Calc. for C81H81BNO5P4ReS2
(1533.56): C, 63.44; H, 5.32; N, 0.91; S, 4.18. Found:
6a: Calc. for C73H71BN2O3P3ReS (1346.37): C, 65.12;
H, 5.32; N, 2.08; S, 2.38. Found: C, 65.37; H, 5.45; N,
1.97; S, 2.28%. KM = 54.3 XÀ1 molÀ1 cm2.
6b: Calc. for C78H73BN2O3P3ReS (1408.44): C, 66.52;
H, 5.22; N, 1.99; S, 2.28. Found: C, 66.34; H, 5.31; N,
2.08; S, 2.21%. KM = 52.6 XÀ1 molÀ1 cm2.
C,
K
63.61; H,
5.43;
N,
1.02; S, 4.05%.
2.2.6. [Re{g2-p-tolyl-NC(H)S}(NO)(PPh3)3]BPh4 (7)
This complex was prepared exactly like the related
thioformamido complexes 5, 6 using ReH2(NO)(PPh3)3
as a precursor; Yield: P70%. Calc. for C86H73BN2-
OP3ReS (1472.53): C, 70.15; H, 5.00; N, 1.90; S, 2.18.
M = 51.8 XÀ1 molÀ1 cm2.
2.2.10. [Re{g1-OC(H)O}(NO){PPh(OEt)2}2-
(PPh3)2]BPh4 (12)
Triflic acid (0.1 mmol, 9 lL) was added to a solution
of ReH2(NO)[PPh(OEt)2](PPh3)2 (0.1 mmol, 94 mg) in
10 mL of CH2Cl2 cooled to À196 °C. The reaction mix-
ture was brought to room temperature, stirred for
30 min and then allowed to stand under CO2 (1 atm)
for 24 h. The solvent was removed under reduced pres-
sure to give an oil which was triturated with ethanol
(2 mL) containing an excess of NaBPh4 (0.3 mmol,
103 mg). By cooling of the resulting solution to
À25 °C, a yellow solid slowly separated out which was
collected by filtration and crystallized from CH2Cl2
and ethanol; Yield: P40%. Calc. for C81H81BNO7P4Re
(1501.44): C, 64.80; H, 5.44; N, 0.93. Found: C, 64.98;
H, 5.61; N, 0.88%. KM = 52.6 XÀ1 molÀ1 cm2.
Found: C, 70.26; H, 5.11; N, 1.79; S, 2.06%. KM
55.3 XÀ1 molÀ1 cm2.
=
2.2.7. [Re{g2-RNC(H)O}(NO){P(OEt)3}(PPh3)2]-
BPh4 (8) [R = p-tolyl (b), Ph (c)] and [Re{g2-p-tolyl-
NC(H)O}(NO)(PPh3)3]BPh4 (10)
These complexes were prepared following the method
used for the related thioformamido complexes 5, 6 using
the appropriate RNCO as a reagent in a 5:1 ratio; Yield:
between 55% (8b, 8c) and 60% (10).
8b: Calc. for C74H73BN2O5P3Re (1360.33): C, 65.34;
H, 5.41; N, 2.06. Found: C, 65.08; H, 5.52; N, 2.12%.
K
M = 55.0 XÀ1 molÀ1 cm2.

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G. Albertin et al. / Inorganica Chimica Acta 358 (2005) 3093–3105
2.2.11. [Re{g2-p-tolyl-NC(H)N-p-tolyl}(NO)-
{P(OEt)3}(PPh3)2]BPh4 (13)
complexes, which react with the heteroallenes to give
the insertion products 1–4 which were isolated as orange
or yellow solids and characterized. A geometry in solu-
tion of the type of Scheme 1 was also established with
the ligand formed upon insertion resulting in g2-coordi-
nated to the metal center.
We also reacted the ReH2(NO)P3 dihydride with
heteroallenes both at room temperature and at reflux,
but no insertion reaction was observed and the starting
complexes were recovered unchanged after several hours
of reaction. The insertion of X@C@Y into rhenium
complexes, therefore, needs the presence of an open
coordination site to occur and the presence of the labile
j1-triflate ligand in ReH(j1-OSO2CF3)(NO)P3 allows
the probable initial coordination of the heteroallene
prior to insertion into the Re–H bond to give the 1–4
derivatives.
An equimolar amount of triflic acid (0.1 mmol, 9 lL)
was added to a solution of ReH2(NO)[P(OEt)3](PPh3)2
(0.1 mmol, 91 mg) in 10 mL of CH2Cl2 cooled to
À196 °C. The reaction mixture was brought to room
temperature, stirred for 30 min and then cooled again
to À196 °C. An excess of p-tolyl-NCN-p-tolyl (1 mmol,
222 mg) in 5 mL of CH2Cl2 was added and the solution,
brought to room temperature, stirred for about 5 h. The
solvent was removed under reduced pressure giving an
oil which was treated with ethanol (2 mL) containing
an excess of NaBPh4 (0.2 mmol, 68 mg). A yellow solid
slowly separated out which was collected by filtration
and crystallized from CH2Cl2 and ethanol; Yield:
P65%. Calc. for C81H80BN3O4P3Re (1449.47): C,
67.12; H, 5.56; N, 2.90. Found: C, 66.95; H, 5.65; N,
2.85%. KM = 54.4 XÀ1 molÀ1 cm2.
Insertion reactions of heteroallene into the M–H
bond of rhenium complexes have few precedents [5]
and the use of dihydride complexes ReH2(NO)P3 as a
precursor allows, after protonation, the facile syntheses
of new dithioformato, thioformamido, formamido and
formamidinato derivatives.
3. Results and discussion
The synthesis of dithioformato (1), thioformamido
(2), formamido (3), and formamidinato (4) complexes
of rhenium was achieved by reacting the ReH2(NO)(P-
Ph2OEt)3 hydride first with triflic acid and then with
the appropriate heteroallene, as shown in Scheme 1.
The reaction of ReH2(NO)(PPh2OEt)3 with
CF3SO3H proceeds [7f] with the evolution of H2 and
formation of the triflate ReH(j1-OSO2CF3)(NO)P3
All the complexes 1–4 were isolated as yellow to or-
ange solids stable in air and in solution of polar organic
solvents, where they behave as 1:1 electrolytes [12]. Ana-
1
lytical and spectroscopic (IR and H, 13C, 31P NMR)
data (Table 1) support the proposed formulation and
a geometry in solution was also established. Attempts
were also made to obtain structural information in the
– H2
ReH2(NO)P3 + CF3SO3H
ReH(κ1-OSO2CF3)(NO)P3
-30 ˚C
+
P
S
S
P
CS
2
Re
CH
CH
CH
CH
ON
P
1 (I)
+
+
+
+
P
Re
P
P
Re
P
R
N
S
P
P
RNCS
CH
+
ON
ON
S
N
R
2 (IIA)
2 (IIB)
ReH(κ1-OSO2CF3)(NO)P3
P
Ph
N
P
PhNCO
Re
ON
O
P
3 (III)
P
R1
N
P
R1NCNR1
Re
P
ON
N
R1
4 (IV)
Scheme 1. P = PPh2OEt; R = Et (a), p-tolyl (b); R1 = p-tolyl.

Table 1
IR and NMR spectroscopic data for rhenium complexes
Complex
IRa (cmÀ1
1729 s
)
Assgnt
1H NMRb,c
Spin system
AB2
31P{1H} NMRb,d
13C{1H} NMRb,e
d (J/Hz)
Assgnt
CH
d (J/Hz)
d (J/Hz)
Assgnt
CH
2
. . .
. . .
[Re{g -S C(H) S}(NO)(PPh2OEt)3]BPh4 (1)
m(NO)
AB2X spin system
(X = 1H)
dX 11.15
JAX = 10.3
JBX = 8.65
3.60 m
dA 112.5
dB 102.6
JAB = 23.5
AB2X spin system
(X = 13C)
dX 234.6
•
•
JAX = 7
JBX = 0.6
65.7 m
15.8 m
CH2
CH3
CH2
CH3
3.45 qnt
1.07 t
0.84 t
2
. . .
. . .
[Re{g -EtN C(H) S}(NO)(PPh2OEt)3]BPh4 (2a)
1722 s
m(NO)
AB2XY2 spin system
(X = 1H)
CH
AB2
AB2
dA 112.8
dB 99.2
JAB = 17.8
176.2 dt
53.1 s
12.5 s
CH
CH2EtN
CH3EtN
•
•
(Y = 1H, CH2)
dX 8.63
JAX = 10.4
JBX = 2.9
dA 111.1
dB 107.8
JAB = 21.0
182.4 t
48.9 s
11.3 s
CH
CH2EtN
CH3EtN
JXY = 1.5
2.97 q
0.66 t
CH2EtN
CH3EtN
65.2 m
15.8 m
CH2phos
CH3phos
AB2XY2 spin system
(X = 1H)
(Y = 1H, CH2)
dX 8.27
CH
JAX = 4.3
JBX = 3.8
JXY = 1.1
1.65 q
CH2EtN
CH3EtN
CH2phos
CH3phos
0.15 t
3.66–3.15 m
1.06 t
1.03 t
2
. . .
. . .
[Re{g -p-tolylN C(H) S}(NO)(PPh2OEt)3]BPh4 (2b)
1710 s
m(NO)
AB2X spin system
(X = 1H)
CH
AB2
AB2
dA 113.8
dB 99.7
JAB = 19.0
AB2X spin system
(X = 13C)
dX 185.9
JAX = 1.1
JBX = 6.1
21.3 s
CH
•
•
dX 9.04
JAX = 5.34
JBX = 3.47
2.20 s
dA 104.5
dB 101.0
JAB = 21.4
CH3p-tol
CH3p-tol
AB2X spin system
(X = 1H)
CH
AB2X spin system
(X = 13C)
CH
dX 8.82
JAX = 10.3
JBX = 3.20
dX 175.4
JAX = 3.9
JBX = 4.5
(continued on next page)

Table 1 (continued)
Complex
IRa (cmÀ1
)
Assgnt
1H NMRb,c
Spin system 31P{1H} NMRb,d
13C{1H} NMRb,e
d (J/Hz)
Assgnt
d (J/Hz)
d (J/Hz)
Assgnt
2.37 s
3.59 m
3.31 qnt
0.99 t
CH3p-tol
CH2
21.0 s
65.6 d
65.4 t
15.8 m
CH3p-tol
CH2
CH3phos
CH
CH3phos
0.94 t
0.85 t
2
. . .
. . .
[Re{g -PhN C(H) O}(NO)(PPh2OEt)3]BPh4 (3)
1722 s
m(NO)
AB2X spin system
(X = 1H)
dX 8.23
JAX = 4
JBX = 4
AB2
dA 117.7
dB 108.0
JAB = 17.2
165.7 t
65.6 d
65.0 t
15.6 t
15.3 d
CH
CH2
•
•
CH3
3.60–3.15 m
0.75 t
0.57 t
CH2
CH3
2
. . .
. . .
[Re{g -p-tolylN C(H) Np-tolyl}(NO)(PPh2OEt)3]BPh4 (4)
1723 s
m(NO)
7.70 m
3.55 qnt
3.28 m
2.25 s
CH
CH2
AB2
dA 112.5
dB 107.2
JAB = 21.8
156.8 t
65.6 m
20.8 s
CH
CH2
•
•
CH3p-tol
CH3p-tol
20.4 s
15.9 m
2.23 s
1.03 t
0.97 t
CH3phos
CH3phos
2
. . .
. . .
[Re(g -EtN C(H) S)(NO){P(OEt)3}(PPh3)2]BPh4 (5a)
1684 s
m(NO)
2.01 q
0.40 t
CH2EtN
CH3EtN
AB2
AB2
dA 97.9
dB 16.2
JAB = 18.0
•
•
1.65 q
0.63 t
CH2EtN
CH3EtN
dA 98.4
dB 15.6
JAB = 18.0
3.60 m
1.11 t
1.07 t
CH2phos
CH3phos
2
. . .
. . .
[Re(g -p-tolylN C(H) S)(NO){P(OEt)3}(PPh3)2]BPh4 (5b)
1707 s
m(NO)
6.90 m
3.63 m
2.29 s
2.19 s
1.13 t
1.10 t
CH
CH2
AB2
dA 97.95
dB 16.5
JAB = 18
186.5 s, br
184.1 s, br
64.3 m
CH
•
•
CH3p-tol
CH2
CH3p-tol
25.5 s
20.9 s
CH3phos AB2
dA 97.95
dB 15.0
JAB = 18
15.94 s
15.80 s
CH3phos
2
. . .
. . .
[Re(g -EtN C(H) S)(NO){PPh(OEt)2}(PPh3)2]BPh4 (6a)
1695 s
m(NO)
6.66 m
CH
AB2
AB2
dA 125.4
dB 15.2
JAB = 13
36.0 s
13.1 s
CH2EtN
CH3EtN
•
•
2.06 q
0.65 t
CH2EtN
CH3EtN
35.7 s
12.8 s
CH2EtN
CH3EtN
dA 125.1
dB 15.8
JAB = 13
1.71 q
0.41 t
CH2EtN
CH3EtN
186.4 s, br
CH

184.8 s, br
64.9 s, br
64.7 s, br
15.8 s
3.71 m
1.07 t
1.06 t
CH2phos
CH3phos
CH2phos
CH3phos
15.3 s
2
. . .
. . .
[Re(g -p-tolylN C(H) S)(NO){PPh(OEt)2}(PPh3)2]BPh4 (6b) 1699 s
m(NO)
6.68 m
3.73 m
2.35 s
2.23 s
1.06 t
1.05 t
CH
CH2
AB2
dA 126.0
dB 15.4
JAB = 13
185.6 s, br
183.6 s, br
64.8 m
21.1 s
CH
•
•
CH3p-tol
CH2
CH3p-tol
CH3phos AB2
dA 125.0
dB 15.7
JAB = 13
20.9 s
15.9 s
15.7 s
CH3phos
2
. . .
. . .
[Re(g -p-tolylN C(H) S)(NO)(PPh3)3]BPh4 (7)
1694 s
m(NO)
2.39 s
2.25 s
CH3
A2B
A2B
dA 3.90
dB 0.19
JAB = 9
187.8 s, br
185.2 s, br
21.1 s
CH
•
•
CH3
21.6 s
dA 2.95
dB 0.74
JAB = 9
2
. . .
. . .
[Re{g -p-tolylN C(H) O}(NO){P(OEt)3}(PPh3)2]BPh4 (8b)
1710 s
m(NO)
6.85 m
6.79 m
3.65 m
2.29 s
2.21 s
1.04 t
CH
AB2
dA 98.6
dB 17.0
JAB = 17
163.3 m, br
161.9 m, br
64.3 d
CH
•
•
CH2
CH3p-tol
CH2
63.1 d
AB2
AB2
dA 97.8
dB 16.5
JAB = 21
20.8 s, br
15.8 s
15.7 s
CH3p-tol
CH3phos
CH3phos
2
. . .
. . .
[Re{g -PhN C(H) O}(NO){P(OEt)3}(PPh3)2]BPh4 (8c)
1709 s
m(NO)
6.39 m
3.64 m
1.16 t
CH
dA 98.3
dB 16.7
JAB = 18
•
•
CH2
CH3
1.01 t
AB2
dA 97.8
dB 17.2
JAB = 18
[Re{g1-p-tolylNC(H)@O}(NO){PPh(OEt)2}2(PPh3)2]BPh4 (9b)
1701 s
1664 m
m(NO)
m(CO)
6.69 m
3.10 m
2.87 m
2.29 s
CH
CH2
A2B2
dA 131.8
dB 5.19
JAB = 22
CH3p-tol
CH3phos
0.62 t
[Re{g1-PhNC(H)@O}(NO){PPh(OEt)2}2(PPh3)2]BPh4 (9c)
1702s
1660 m
m(NO)
m(CO)
6.67 m
3.10 m
2.87 m
0.62 t
CH
CH2
A2B2
dA 131.8
dB 5.19
JAB = 22
161.2 m, br
63.5 s, br
15.3 s, br
CH
CH2
CH3
CH3
CH3
2
. . .
. . .
[Re{g -p-tolylN C(H) O}(NO)(PPh3)3]BPh4 (10)
1699 s
m(NO)
2.39 s
2.22 s
A2B
dA 6.79
dB 4.12
JAB = 6.5
•
•
(continued on next page)

Table 1 (continued)
Complex
IRa (cmÀ1
)
Assgnt
1H NMRb,c
Spin system 31P{1H} NMRb,d
13C{1H} NMRb,e
d (J/Hz)
Assgnt
d (J/Hz)
d (J/Hz)
Assgnt
A2B
dA 6.09
dB 3.27
JAB = 7.3
[Re{g1-SC(H)@S}(NO){PPh(OEt)2}2(PPh3)2]BPh4 (11)
1709 s
m(NO)
6.72 m
3.12 m
2.89 m
0.64 t
CH
CH2
A2B2
dA 131.8
dB 5.21
JAB = 22
CH3
[Re{g1-OC(H)@O}(NO){PPh(OEt)2}2(PPh3)2]BPh4 (12)
1706 s
1662 m
m(NO)
m(CO)
6.73 m
3.64 m
0.64 t
CH
A2B2
AB2
dA 131.8
dB 5.21
JAB = 22
176.8 s, br
65.4 d
15.9 d
CH
CH2
CH3
CH2
CH3
2
. . .
. . .
[Re(g -p-tolylN C(H) Np-tolyl)(NO){P(OEt)3}(PPh3)2]BPh4 (13) 1700 s
m(NO)
AB2X spin system
(X = 1H)
dX 6.59
JAX = 24
JBX = 8
3.96 m
CH
dA 105.3
dB 12.0
JAB = 18
•
•
CH2
AB2
dA 100.3
dB 12.7
JAB = 19.5
3.68 m
3.49 m
2.33 s
2.22 s
CH3p-tol
1.12 t
1.01 t
CH3phos
a
b
c
In KBr pellets.
In CD2Cl2 at 25 °C.
Phenyl proton resonances omitted.
Positive shift downfield from 65% H3PO4.
Phenyl carbon resonances omitted.
d
e

G. Albertin et al. / Inorganica Chimica Acta 358 (2005) 3093–3105
3101
solid state for the complexes, but the poor quality of the
obtained crystals prevented any X-ray determination.
spectra confirm the presence of the formamido ligand
showing the CH carbon resonance as a multiplet at
165.7 ppm. In the HMQC experiment, this signal corre-
lates with the proton multiplet at 8.23 ppm, in agree-
ment with the proposed attributions. In the
temperature range between +20 and À80 °C, the
31P{1H} NMR spectra of the formamido complex 3 ap-
pear as a AB2 multiplet, suggesting the presence of two
phosphines magnetically equivalent and different from
the third. These data, however, do not allow to unam-
biguously assign a geometry for the complex, i.e., do
not allow to distinguish between a geometry with the
1
The H NMR spectrum of the thioformato Re{g2-
. . .
. . .
C(H) S}(NO)(PPh2OEt)3]BPh4 (1) complex shows
S
•
•
a multiplet at 11.15 ppm attributed to the CH proton
[2,3,5] of the thioformato ligand. The multiplicity of
the signal is due to the coupling with the phosphorus nu-
clei of the phosphine and the related NMR parameters
(Table 1) can be obtained by simulation of the spectra
using an AB2X (X = 1H) model. The 13C{1H} NMR
spectra support the presence of the SC(H)S ligand show-
ing a AB2X (X = 13C) multiplet centered at 234.6 ppm of
the thioformato carbon atom which, in the HMQC
experiments, correlates with the CH proton signal at
11.15 ppm of the SC(H)S ligand. In the temperature
range between +20 and À80 °C, the 31P{1H} NMR spec-
tra appear as an AB2 multiplet, in agreement with the
presence of two phosphites magnetically equivalent
and different from the third. Furthermore, the 1H
NMR spectra of 1 show, beside the phenyl and methyl
proton signals, also a quintet at 3.45 and a multiplet
at 3.60 ppm attributed to the methylene protons of the
PPh2OEt ligands. The presence of a multiplet [13], be-
side the quintet, suggests that two of the three phosph-
ites are in a mutually trans position. Finally, the IR
spectrum shows one strong band at 1729 cmÀ1 attrib-
uted to m(NO) of the nitrosyl ligand. On the basis of
these data, a geometry of type I (Scheme 1) can reason-
ably be proposed for the dithioformato complex 1.
NO in the trans or in the cis position with respect to
2
. . .
. . .
the N atom of the g -RN C(H) O ligand. However,
•
•
the IR spectra show the m(NO) at the same values
(1722 cmÀ1) of the formamidinato complex 4 (see below)
which contains a similar group trans to the NO and,
therefore, by analogy a geometry of type III (Scheme
1) for the formamido derivatives 3 can be reasonably
proposed.
The formation of only one isomer in this case is
somewhat surprising as compared to the related thiofor-
mamido derivative 2 and may be explained on the basis
of a greater stability of one isomer with respect to the
other.
The proton spectra of the formamidinato complex 4
show a multiplet at 7.70 ppm due to the CH proton
and two singlets at 2.25 and 2.23 ppm of the p-tolyl
. . .
. . .
group of the p-tolyl-N C(H) N-p-tolyl ligand. The
•
•
The 1H NMR spectra of both the thioformamido
magnetic inequivalence of the p-tolyl-substituent is con-
firmed by the 13C spectra, which show two singlets at
20.8 and 20.4 ppm of the CH3 groups. In the spectra,
a multiplet at 156.8 ppm, which correlates with the pro-
ton multiplet at 7.70 ppm in the HMQC experiment, is
present and was attributed to the CH carbon resonance
2
. . .
. . .
[Re{g -RN C(H) S}(NO)P3]BPh4 (2a and 2b) com-
•
•
plexes show two CH multiplets [2,3,5] at 8.63, 8.27
(2a) and at 9.04, 8.82 (2b) ppm and two signals for the
substituent R of the RNC(H)S ligand. The COSY exper-
iment allowed the easy attribution of the signals re-
ported in Table 1. These results seem to suggest the
presence of two isomers of the types shown in Scheme
1, with the NO ligand in a mutually trans position with
the sulfur atom of RNC(H)S in one case, and in cis in
the other. This is confirmed by the 31P NMR spectra,
which show two AB2 multiplets, and by the 13C spectra
whose CH carbon resonances appear as two well-
resolved multiplets at 182–176 (2a) and 185–175 (2b)
ppm. In the spectra, two sets of signals for the substitu-
ents R of the RNC(H)S ligands are also observed, while
the HMQC experiments show the correlation between
the two CH proton signals between 8.26 and 9.02 ppm
with the two multiplets in the 13C spectra at 182–
185 ppm of the CH carbon resonance of the thiofor-
mamido ligand. On the basis of these data, the geometry
of Scheme 1 for the two isomers of complexes 2 can rea-
sonably be proposed.
. . .
of the p-tolyl–N C(H) N-p-tolyl ligand. Taking into
. . .
•
•
account that in the temperature range between +20 and
À80 °C the 31P spectra appear as a AB2 multiplet, a
type-IV geometry (Scheme 1) for the formamidinato
complex 4 can reasonably be proposed.
Mixed-ligand hydrides with PPh3 and phosphites of
the ReH2(NO)L(PPh3)2 [10] and ReH2(NO)(PPh3)3
[11] type also allowed the synthesis of dithioformato,
thioformamido and formamido derivatives after treat-
ment with CF3SO3H, but, in this case, the stoichiometry
of the complexes depends on the nature of the phos-
phine and of the heteroallene, as shown in Scheme 2.
All the hydrides ReH2(NO)L(PPh3)2 and ReH2(NO)
(PPh3)3 react first with equimolecular amounts of
CF3SO3H to give the ReH(j1-OSO2CF3)(NO)L(PPh3)2
and ReH(j1-OSO2CF3)(NO)(PPh3)3 intermediates [10],
which further react with RNCS (R = Et, p-tolyl) to yield
2
. . .
. . .
Surprisingly, only one isomer has been observed for
2
the final thioformamido [Re{g -RN C(H) S}
•
•
2
. . .
. . .
. . .
. . .
the formamido [Re{g -PhN C(H) O}(NO)P3]BPh4
(NO)L(PPh3)2]BPh4 (5, 6) and [Re{g -RN C(H) S}
•
(3) complex, whose H NMR spectra show only one
•
•
•
1
(NO)(PPh3)3]BPh4 (7) complexes. Surprisingly, the reac-
tion of isocyanate R1NCO (R1 = Ph, p-tolyl) with the
multiplet for the CH resonance at 8.23 ppm. The 13C

3102
G. Albertin et al. / Inorganica Chimica Acta 358 (2005) 3093–3105
– H2
ReH2(NO)L(PPh3)2 + CF3SO3H
ReH(κ1-OSO2CF3)(NO)L(PPh3)2
ReH(κ1-OSO2CF3)(NO)(PPh3)3
L = P(OEt)3, PPh(OEt)2
– H2
ReH2(NO)(PPh3)3 + CF3SO3H
+
+
P
P
R
N
S
L
L
exc. RNCS
ReH(κ1-OSO2CF3)(NO)L(PPh3)2
Re
CH
Re
CH
+
ON
ON
S
N
R
L = P(OEt)3 5, PPh(OEt)2
R = Et a, p-tolyl b
6
P
P
(VA)
5, 6
(VB)
+
+
P
P
R
N
S
P
P
exc. RNCS
ReH(κ1-OSO2CF3)(NO)(PPh3)3
R = p-tolyl
Re
CH
Re
CH
+
ON
ON
S
N
R
P
P
(VIIA)
(VIIB)
7
+
+
P
P
R1
N
O
L
L
exc. R1NCO
ReH(κ1-OSO2CF3)(NO)L(PPh3)2
Re
CH
Re
CH
+
ON
ON
O
N
L = P(OEt)3
5
R1
R1 = Ph c, p-tolyl b
P
P
(VIIIA)
8
(VIIIB)
ReH(κ1-OSO2CF3)(NO)L(PPh3)2
exc. R1NCO
exc. R1NCO
[Re{η1-R1NC(H)=O}(NO)L2(PPh3)2]+
L = PPh(OEt)2
R1 = Ph c, p-tolyl b
9
+
+
P
P
R1
N
O
P
P
ReH(κ1-OSO2CF3)(NO)(PPh3)3
Re
CH
Re
CH
+
ON
ON
O
N
R1 = Ph
R1
P
P
(XA)
(XB)
10
Scheme 2.
j1-triflate gives the g2-formamido derivatives 8 and 10
only with the ReH(j1-OSO2CF3)(NO){P(OEt)3}(PPh3)2
and ReH(j1-OSO2CF3)(NO)(PPh3)3 precursors. How-
ever, with the ReH(j1-OSO2CF3)(NO){PPh(OEt)2}
(PPh3)2 hydride, containing the PPh(OEt)2 phosphite li-
gand, the reaction with isocyanate gives a new complex
of the [Re{g1-RNC(H)@O}(NO){PPh(OEt)2}2(PPh3)2]
BPh4 (9) type whose characterization data suggest the
presence of a g1-coordinate formamido ligand. In this
case, the insertion of RNCO is followed by a phosphine
exchange between the species, yielding the final complex
9 containing two PPh(OEt)2 and two PPh3 ligands. The
coordination of the fourth phosphine also suggests that
in these complexes the g2-coordination of the form-
amido R1NC(H)O is not favored and makes the related
complexes unstable, which probably promotes the phos-
phite exchange giving the more stable g1-derivative 9.
Carbon disulfide also reacts with the hydride-triflate
ReH(j1-OSO2CF3)(NO)L(PPh3)2 and ReH(j1-OSO2-
CF3)(NO)(PPh3)3 intermediates, but in only one case
the insertion product [Re{g1-SC(H)@S}(NO){PPh
(OEt)2}2(PPh3)2]BPh4 (11) can be isolated in pure form
and characterized (Scheme 3). In the other cases, intrac-
table mixtures of products were always obtained.
Furthermore, we extensively studied the reaction of
CO2 with all the triflate ReH(j1-OSO2CF3)(NO)L3 com-
plexes (L = phosphites or PPh3), and observed that the
reaction does proceed, but is slow and often gives unsta-
ble complexes. In only one case, a solid sample of the
compound was isolated in pure form and characterized
as containing the g1-formate [Re{g1-OC(H)@O)(NO)
{P(OEt)3}2(PPh3)2]BPh4 (12) derivative (Scheme 3). A
phosphite exchange takes place also in these reac-
tions of both CO2 and CS2 molecules, giving the

G. Albertin et al. / Inorganica Chimica Acta 358 (2005) 3093–3105
3103
exc. CS2
ReH(κ1-OSO2CF3)(NO)L(PPh3)2
[Re{η1-SC(H)S}(NO)L2(PPh3)2]+
11
L = PPh(OEt)2
CF3SO3H
[Re{η1-OC(H)O}(NO)L2(PPh3)2]+
ReH(κ1-OSO2CF3)(NO)L(PPh3)2
CO2, 1 atm
12
L = PPh(OEt)2
+
+
L
P
Re
P
R2
R2
N
N
P
L
exc. R2NCNR2
ReH(κ1-OSO2CF3)(NO)L(PPh3)2
Re
CH
CH
+
P
ON
N
N
L = P(OEt)3
R2 = p-tolyl
R2
R2
N
O
(XIIIA)
13
(XIIIB)
Scheme 3.
tetrakis(phosphite) derivatives containing the insertion
products g1-coordinated to the metal center.
Finally, 1,3-di-p-tolylcarbodiimide reacts with
ReH(j1-OSO2CF3)(NO)L(PPh3)2 to give the p-tolyl-
formamidinato complex 13 which, in the case of
P(OEt)3, was isolated as an orange solid and
characterized.
ported by the presence of two CH resonances at 163.3
and 161.9 ppm in the 13C spectra of 8b which, in a
HMQC experiment, correlate with the two 1H multiplets
near 6.8 ppm due to the CH proton of the RNC(H)O li-
gand. Furthermore, two AB2 multiplets were observed
in the 31P spectra, in agreement with the geometries
VIIIA, VIIIB and XA, XB for the complexes.
All the complexes 5–13 are stable as solids and in a
solution of polar organic solvents, where they behave
as 1:1 electrolytes [12]. Their formulation is confirmed
by the analytical and spectroscopic data reported in
Table 1.
Surprisingly, the reaction with isocyanates of the
ReH(j1-OSO2CF3)(NO){PPh(OEt)2}-
mixed-ligand
(PPh3)2 hydride complexes, containing PPh(OEt)2 as
a ligand, yields a compound formulated as [Re-
{g1-RNC(H)@O}(NO){PPh(OEt)2}2(PPh3)2]BPh4 (9)
containing the formamido R1NC(H)@O bonded in a
g1-fashion to the central metal.
Like the PPh2OEt derivatives 2, the thioformamido
2
. . .
. . .
[Re{g -RN C(H) S}(NO)L(PPh3)2]BPh4 (5, 6) and
•
•
2
. . .
. . .
[Re{g -RN C(H) S}(NO)(PPh3)3]BPh4 (7) com-
The IR spectra of complexes 9 show a medium-inten-
sity band at 1664 (9b) and at 1660 cmÀ1 (9c) attributable
to m(CO) of the g1-RNC(H)@O ligand. The strong
m(NO) band at 1702–1701 cmÀ1 is also observed. The
1H NMR spectra show a multiplet at 6.69 (9b) and at
6.67 (9c) ppm due to the CH signal of the RNC(H)O li-
gand. The 13C NMR spectra support the presence of the
formamido showing a multiplet at 161.2 ppm (9c) which
correlates, in the HMQC experiment, with the proton
multiplets at 6.67 ppm. In the temperature range be-
tween +20 and À80 °C, the 31P{1H} NMR spectra ap-
pear as a A2B2 multiplet for both the complexes 9b
and 9c, suggesting the presence of four phosphine li-
gands two by two magnetically equivalent. The values
of the chemical shifts (Table 1) also indicate the presence
of both the PPh3 and PPh(OEt)2 phosphine ligands,
while the value of 22 Hz for JPP(JAB) seems to suggest,
by a comparison with the values of related complexes
1–8, that the different phosphines PPh(OEt)2 and PPh3
are in a mutually cis position. On the basis of these data,
a geometry of the type IX can be tentatively proposed
for complexes 9 (Chart 1).
•
•
plexes, containing the PPh3 ligand, showed the presence
of two isomers of the type shown in Scheme 2.
Two multiplets for the CH carbon resonances of
RNC(H)S ligand were observed in the 13C spectra at
187–183 ppm (Table 1), which correlate, in the HMQC
experiments, with the two multiplets at 6.90–6.68 ppm
due to CH proton resonances observed in the 1H
NMR spectra. In the temperature range between +20
and À80 °C, the 31P NMR spectra appear as two AB2
or A2B multiplets indicating that in both isomers two
phosphines are magnetically equivalent and different
from the third. On the basis of these data, the geometry
of type V for 5, 6 and of type VII for 7 may reasonably
be proposed.
Depending on the nature of the phosphite ligands, the
reaction of isocyanate R1NCO with the mixed-ligand
ReH(j1-OSO2CF3)L(PPh3)2 hydride gives either g2-
RNC(H)O (8, 10) or g1-RNC(H)O (9) formamido
derivatives (Scheme 2). Furthermore, the chelate
2
. . .
. . .
[Re{g -RN C(H) O}(NO){P(OEt)3}(PPh3)2]BPh4
•
•
2
. . .
. . .
(8) and [Re{g -RN C(H) O}(NO)(PPh3)3]BPh4 (10)
complexes were obtained as a mixture of two isomers of
the type shown in Scheme 2. This hypothesis is sup-
•
•
The formation of the tetrakis(phosphine) complexes 9
containing the monodentate formamido ligand may be

3104
G. Albertin et al. / Inorganica Chimica Acta 358 (2005) 3093–3105
+
+
+
NO
Re
N
NO
Re
S
NO
Re
O
P
L
P
L
P
L
L
L
L
P
P
P
O
S
O
R
C
H
C
H
C
H
9 (IX)
11 (XI)
12 (XII)
Chart 1. P = PPh3, L = PPh(OEt)2.
Chart 2.
due to the instability of the initial [Re{g2-RNC(H)@O}
(NO){PPh(OEt)2}(PPh3)2]+ complex formed [A], which
can give an unstable pentacoordinate intermediate [B]
(Scheme 4).
The presence of the thioformato ligand in 11 is con-
firmed by the characteristic multiplet of the CH proton
of the SC(H)S ligand observed at 6.72 ppm in the proton
NMR spectra. The 31P spectra appear as a A2B2 multi-
plet with JPP of 22 Hz. On the basis of these data, a
geometry of type XI like that of the formamido deriva-
tives 9 can reasonably be proposed (Chart 2).
A phosphite exchange between two molecules of this
intermediate [B] can take place, giving the stable octahe-
dral final complex 9. Studies on the reaction course
show that the product isolated in the initial stage of
the reaction (after about 30 min) contains, beside the
starting ReH(j1-OSO2CF3)(NO)L(PPh3)2 and the final
complex 9, a species supposed to be (by NMR) the che-
late [Re{g2-RNC(H)@O}(NO)L(PPh3)2]BPh4 complex
[A]. The formation of this species and the presence of
free phosphite in the reaction mixture support the path
proposed in Scheme 4 for the reaction.
The IR spectrum of the formato [Re{g1-OC(H)@O}
(NO){PPh(OEt)2}2(PPh3)2]BPh4 (12) complex shows a
medium absorption at 1662 cmÀ1 attributed to mas(CO2)
of the g1-formato ligand. Other g1-formato complexes
show mas(CO2) bands in the 1667–1603 cmÀ1 range [14],
whereas g2-formato generally show mas(CO2) bands [15]
between 1585 and 1554 cmÀ1. In the spectra, a strong
absorption at 1706 cmÀ1 is also observed, due to the
m(NO) of the nitrosyl ligand.
The g1-coordination of the ligand is also observed
in both the thioformato [Re{g1-SC(H)@S}(NO)-
{PPh(OEt)2}2 (PPh3)2]BPh4 (11) and formato [Re-
The 13C NMR spectra confirm the presence of the
formato ligand showing a broad singlet at 176.8 ppm
1
due to the formato carbon atom. The H spectra do
{g1-OC(H)@O}(NO){PPh(OEt)2}2(PPh3)2]BPh4
(12)
complexes obtained in the reaction of Re(j1-OSO2CF3)
(NO)L(PPh3)2 with CS2 and CO2, respectively. A reaction
path of the type of Scheme 4 may also be invoked in these
cases, which lead to the separation of stable complexes of
the types of 11 and 12.
not allow us to clearly assign the formyl CH resonance,
due to the overlapping with the phenyl proton signals.
However, a HMQC experiment clearly shows the corre-
lation between a signal at 6.73 ppm in the proton NMR
spectra and the singlet due to the 13C formyl carbon res-
onance at 176.8 ppm, in agreement with the presence of
the formato ligand. In the temperature range between
+20 and À80 °C, the 31P spectra appear as a A2B2 mul-
tiplet with JPP(JAB) of 22 Hz. On the basis of these data,
a geometry of type XII (Chart 2) can reasonably be pro-
posed for the formato complex 12.
+
P
R1
N
L
R1NCO
ReH(κ1-OSO2CF3)(NO)LP2
Re
CH
ON
O
P
[A]
Formato complexes obtained by insertion of CO2
into the metal–hydride bond are of interest as an impor-
tant chemical step in functionalizing this molecule [1–3].
The preparation of [Re(g1-OC(H)@O)(NO){PPh-
(OEt)2}2(PPh3)2]BPh4 is a new example involving, for
the first time, rhenium as the central metal.
The formamidinato [Re{g2-p-tolylNC(H)Np-tolyl}
(NO){P(OEt)3}(PPh3)2]BPh4 (13) complex was sepa-
rated as an orange solid containing two isomers. The
1H NMR spectrum shows, in fact, two CH multiplets
at 6.59 and 5.96 ppm, while two AB2 patterns are
+
+
P
NO
Re
N
R1
C
L
P
L
ON
P
L
Re
P
N
H
L
O
O
R1
C
H
[B]
9
P = PPh3, L = PPh(OEt)2
Scheme 4.

G. Albertin et al. / Inorganica Chimica Acta 358 (2005) 3093–3105
3105
present in the 31P spectrum. In the proton spectra, two
signals at 2.33 and 2.22 ppm for the methyl groups of
the p-tolyl substituents are also present. On the basis
of these data, geometries of types XIIIA and XIIIB
can be proposed for the two isomers of the formamidi-
nato complex 13.
(j) A. Mishra, U.C. Agarwala, Inorg. Chim. Acta 145 (1988)
191;
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4. Conclusions
In this report, we have highlighted that the use of the
hydride-triflate complexes of the ReH(j1-OSO2CF3)
(NO)(PPh2OEt)3 and ReH(j1-OSO2CF3)(NO)LP2 type
as precursors allows the facile insertion of heteroallene
CS2, RNCS, RNCO, and R1NCNR2 into the Re–H
bond giving a series of dithioformato, thioformamido,
formamido and formamidinato derivatives. The influ-
ence of the phosphite ligand on the reactions, yielding
either g2- or g1-complexes, was also established.
Finally, carbon dioxide inserts into the Re–H bond
yielding the stable formato [Re{g1-OC(H)@O}(NO)
{PPh(OEt)2}2(PPh3)2]BPh4 derivative.
(b) P. Munshi, A.D. Main, J.C. Linehan, C.-C. Tai, P.G. Jessop,
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Acknowledgments
[7] (a) G. Albertin, S. Antoniutti, M. Bettiol, E. Bordignon, F.
Busatto, Organometallics 16 (1997) 4959;
´
(b) G. Albertin, S. Antoniutti, S. Garcia-Fontan, R. Carballo, F.
The financial support of MIUR (Rome) – PRIN 2004
– is gratefully acknowledged. We thank Daniela Baldan
for technical assistance.
Padoan, J. Chem. Soc., Dalton Trans. (1998) 2071;
(c) G. Albertin, S. Antoniutti, E. Bordignon, F. Menegazzo, J.
Chem. Soc., Dalton Trans. (2000) 1181;
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(2004) 1328;
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