Synthesis and reactivity of dinuclear iron-platinum, chromium-platinum, molybdenum-platinum and tungsten-platinum complexes with bridging carbonyl, isocyanide and aminocarbyne ligands. An empirical study on the parameters decisive for the bonding mode of the isocyanide ligand

Article abstract of DOI:10.1016/S0022-328X(03)00752-6

The dppm-bridged heterobimetallic μ-carbonyl complexes [(OC) ₄M(μ-CO)(μ-dppm)Pt(PPh₃)] (1a, M=Cr; 1b, M=Mo; 1c, M=W) have been prepared by the reaction of [M(CO)₅ (η¹-dppm)] (M=Cr, Mo, W) with [Pt(CH₂CH ₂)(PPh₃)₂]. The outcome of stoichiometric isocyanide addition to 1 is electronically controlled by the π-accepting propensity of CNR. Addition of isocyanide ligands with strongly electron withdrawing substituents R affords the isonitrile-bridged complexes [(OC)₄M(μ-C=N-R) (μ-dppm)Pt(PPh₃)] 2 (M=W; R=CF₃), 3 (3a, M=Cr; 3b M=Mo, 3c M=W; R=CH₂SO₂p-tolyl), and 4 (M=W; R=[CH₂PPh₃][PF₆]. With less π-accepting isocyanides (R=CH₂Ph, C₆ H₁₁, CH₂PO(OEt)₂,) the labile complexes [(RNC)(OC)₃W(μ-C=O)(μ-dppm)Pt (PPh₃)] (5-7) ligated by a terminal isonitrile ligand are formed. In contrast, treatment of [(OC)₃Fe(μ-CO)(μ-dppm) Pt(PPh₃)] with CNCH₂PO(OEt)₂ yields exclusively [(OC)₃Fe{μ-C=NCH₂PO(OEt) ₂}(μ-dppm)Pt(PPh₃)] (9) with the isocyanide ligand in a bridging bonding mode. Upon protonation of 2 and 3b with HBF₄, the stable μ-aminocarbyne complexes [(OC)₄ M(μ-C=N(H)R′)(μ-dppm)Pt(PPh₃)] [BF₄] (10-11) are formed by electrophilic addition of H⁺ on the basic isonitrile nitrogen atom. The molecular structures of 1a,c, 2 and 3c have been determined by X-ray diffraction methods. The μ-CO and the μ-CNR ligands bridge the metal centres in an asymmetric manner, the Pt-μ-C distances being significantly shorter than the corresponding M-μ-C distances. In contrast, the μ-CNCH₂PO(OEt)₂ ligand of [(OC)₃ Fe{μ-C=N-CH₂PO(OEt)₂}(μ-dppm)Pt (PPh₃)] (9) bridges symmetrically the two metal centres. Furthermore, the molecular structure of cis -[(benzylNC)(OC)₄ W(η¹-dppm)] (8a) resulting from degradation of 5 has been determined.

Full text of DOI:10.1016/S0022-328X(03)00752-6

Journal of Organometallic Chemistry 684 (2003) 216ꢀ229
/
www.elsevier.com/locate/jorganchem
Synthesis and reactivity of dinuclear ironꢀ
/
platinum, chromiumꢀ
/
platinum, molybdenumꢀplatinum and tungstenꢀ
/
/
platinum complexes
with bridging carbonyl, isocyanide and aminocarbyne ligands. An
empirical study on the parameters decisive for the bonding mode of
the isocyanide ligand
Michael Knorr a,*, Isabelle Jourdain a, Dieter Lentz b, Stefan Willemsen b,
Carsten Strohmann c
a Laboratoire de Chimie des Mate´riaux et Interfaces, Universite´ de Franche-Comte´, Faculte´ des Sciences et des Techniques, 16, Route de Gray,
25030Besancon Cedex, France
¸
b Institut fur Anorganische und Analytische Chemie, FreieUniversitat Berlin, Fabeckstrasse 34-36, D-14195 Berlin, Germany
¨
¨
c Institut fur Anorganische Chemie der Universitat Wurzburg, Am Hubland, D-97074 Wurzburg, Germany
¨
¨
¨
¨
Received 24 April 2003; received in revised form 2 July 2003; accepted 2 July 2003
Dedicated to Prof. E.O. Fischer on the occasion of his 85th birthday
Abstract
The dppm-bridged heterobimetallic m-carbonyl complexes [(OC)4M(m-CO)(m-dppm)Pt(PPh3)] (1a, Mꢁ
W) have been prepared by the reaction of [M(CO)5(h1-dppm)] (Mꢁ
Cr, Mo, W) with [Pt(CH2CH2)(PPh3)2]. The outcome of
stoichiometric isocyanide addition to 1 is electronically controlled by the p-accepting propensity of CNR. Addition of isocyanide
ligands with strongly electron withdrawing substituents R affords the isonitrile-bridged complexes [(OC)4M(m-CÄNꢀR)(m-
dppm)Pt(PPh3)] 2 (MꢁW; RꢁCF3), 3 (3a, MꢁCr; 3b MꢁMo, 3c MꢁW; RꢁCH2SO2p-tolyl), and 4 (MꢁW; Rꢁ
[CH2PPh3][PF6]. With less p-accepting isocyanides (RꢁCH2Ph, C6H11, CH2PO(OEt)2,) the labile complexes [(RNC)(OC)3W(m-
7) ligated by a terminal isonitrile ligand are formed. In contrast, treatment of [(OC)3Fe(m-CO)(m-
/
Cr; 1b, Mꢁ
/
Mo; 1c, Mꢁ
/
/
/
/
/
/
/
/
/
/
/
/
/
CÄ
/
O)(m-dppm)Pt(PPh3)] (5
/
ꢀ
dppm)Pt(PPh3)] with CNCH2PO(OEt)2 yields exclusively [(OC)3Fe{m-CÄ
/
NCH2PO(OEt)2}(m-dppm)Pt(PPh3)] (9) with the
isocyanide ligand in a bridging bonding mode. Upon protonation of 2 and 3b with HBF4, the stable m-aminocarbyne complexes
[(OC)4M(m-CÄ
/
N(H)R?)(m-dppm)Pt(PPh3)][BF4] (10
/
11) are formed by electrophilic addition of Hꢂ on the basic isonitrile nitrogen
ꢀ
atom. The molecular structures of 1a,c, 2 and 3c have been determined by X-ray diffraction methods. The m-CO and the m-CNR
ligands bridge the metal centres in an asymmetric manner, the Ptꢀ
/
m-C distances being significantly shorter than the corresponding
Mꢀ
/
m-C distances. In contrast, the m-CNCH2PO(OEt)2 ligand of [(OC)3Fe{m-CÄ
/
NꢀCH2PO(OEt)2}(m-dppm)Pt(PPh3)] (9) bridges
/
symmetrically the two metal centres. Furthermore, the molecular structure of cis-[(benzylNC)(OC)4W(h1-dppm)] (8a) resulting
from degradation of 5 has been determined.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Isocyanide; Platinum; Tungsten; Molybdenum; Chromium; Iron; Metalꢀmetal bonds
/
1. Introduction
A common strategy to control ligand arrangements,
reactivity patterns and catalytic activity of mononuclear
phosphane complexes consists in variation of the
electronic and steric propensities (cone angle) of sub-
stituents R of PR3 ligands. In a similar manner, the
* Corresponding author. Fax: ꢂ33-381-666-438.
E-mail address: michael.knorr@univ-fcomte.fr (M. Knorr).
/
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00752-6

M. Knorr et al. / Journal of Organometallic Chemistry 684 (2003) 216ꢀ
/229
217
modification of the substituent R of isocyanides CNR
allows to fine-tune the s-donor/p-acceptor propensities
2.1. Preparation of [(OC)4Cr(m-CO)(m-
dppm)Pt(PPh3)] (1a)
of this versatile class of ligands [1ꢀ3]. In general,
/
textbooks present both terminal and bridging isocya-
nides as stronger s-donor and weaker p-acceptor
ligands compared to carbon monoxide. However, Lentz
has shown that fluorinated isocyanides behave also as
powerful p-acceptor ligands. Especially, trifluoromethyl
isocyanide is one of the strongest known p-acceptors
[Cr(CO)5(h1-dppm)] (1 mmol) was added to a solu-
tion of [Pt(CH2CH2)(PPh3)2] (748 mg, 1 mmol) in 10 ml
of toluene. The solution was stirred at 20 8C for 1 h.
Ethylene evolution was observed and the solution
turned rapidly to yellowꢀorange. After 15 min precipi-
/
tation of the yellow product occurred, which was
completed by slow concentration of the solution under
reduced pressure and subsequent addition of hexane (10
ml). The product was filtered off, rinsed with hexane,
and dried under vacuo (940 mg, 91% yield). This crude
product is sufficiently pure for further reactions; analy-
tically pure samples can be obtained by recrystallisation
which may excel even CO [4ꢀ7]. In the context of our
/
interest in the coordination and activation of unsatu-
rated organic molecules on heterobimetallic complexes
LnMꢀ
the synthesis and reactivity of heterometallic couples
towards isocyanides [8ꢀ14]. In the case of bis(diphenyl-
phoshino)amine-bridged MoꢀPt and WꢀPt complexes
/
M?Ln, we have studied in some precedent papers
/
/
/
from concentrated CH2Cl2ꢀ
mixtures at ꢃ25 8C. Anal. Calc. for C48H37CrO5P3Pt×
CH2Cl2 (1033.82ꢂ84.93): C, 52.60; H, 3.51. Found: C,
52.55; H, 3.65%. IR (KBr): n(CO): 1995s, 1904sh,
/
heptane or tolueneꢀheptane
/
[(OC)4M(m-CÄ
/
O)(m-dppa)Pt(PPh3)], we have noticed
/
/
that reaction with tosylmethyl isocyanide afforded
exclusively isocyanide-bridged complexes [(OC)4M(m-
/
CÄ
/
Nꢀ
/
CH2SO2p-tolyl)(m-dppa)Pt(PPh3)]
(Mꢁ/Mo,
1881vs, 1789m cmꢃ1
.
ꢁ
1H-NMR: dꢁ
29.6 Hz), 6.85ꢀ
/
4.28 (t, PCH2,
7.55 (m, 35H,
2
2H, JP,H
phenyl).
3
8.6, JPt,H
W), whereas treatment with xylyl isocyanide and benzyl
isocyanide yielded very labile complexes
[(RNC)(OC)3W(m-CÄO)(m-dppa)Pt(PPh3)] with term-
ꢁ
/
/
/
/
inal isocyanide ligands [15]. With the aim to evaluate
in more detail the reasons for the different bonding
mode (bridging vs. terminal), we have undertaken a
study with various isocyanides having substituents R
with very diverging electronic and steric features.
2.2. Preparation of [(OC)4Mo(m-CO)(m-
dppm)Pt(PPh3)] (1b)
This complex was prepared as described for 1a (959
mg, 89% yield). Anal. Calc. for C48H37MoO5P3Pt
(1077.82): C, 53.49; H, 3.46. Found: C, 53.85; H,
3.66%. IR (KBr): n(CO): 2010s, 1914sh, 1896vs,
2. Experimental
1800m cmꢃ1
.
1H-NMR: dꢁ
/
4.25 (t, PCH2, 2H,
2JP,H
yl).
ꢁ
/
8.5, 3JPt,H
ꢁ
/
29.0 Hz), 6.88ꢀ
/7.60 (m, 35H, phen-
All reactions were performed in Schlenk-tube flasks
under purified nitrogen. Solvents were dried and dis-
tilled under nitrogen before use, toluene and hexane
over sodium, dichloromethane from P4O10. IR spectra
have been recorded on a Nicolet Nexus 470 spectro-
meter. Elemental C, H analyses were performed on a
2.3. Preparation of [(OC)4W(m-CO)(m-
dppm)Pt(PPh3)] (1c)
This complex was prepared as described for 1a (619
+
1
Leco elemental analyser CHN 900. The H-, 13C{1H}-
mg, 88% yield). Anal. Calc. for C48H37O5P3PtW
2
and 31P{1H}-NMR spectra were recorded at 200.13,
50.32, 81.01, 63.16 and 39.76 MHz, respectively, on a
Bruker ACP 200 instrument and a Bruker Avance 300
CH2Cl2 (1077.82ꢂ
45.25; H, 3.05%. IR (KBr): n(CO): 2011s, 1914sh,
1894vs, 1782m cmꢃ1 1H-NMR: dꢁ
4.48 (dt, PCH2,
2H, 2JP,H 8.8 and 1.5, 3JPt,H
34.0 Hz), 6.85ꢀ7.54 (m,
35H, phenyl).
/169.86): C, 44.97; H, 3.09. Found: C,
.
/
1
instrument (300.13 MHz for H). 195Pt chemical shifts
ꢁ
/
ꢁ
/
/
were measured on a Bruker ACP 200 instrument (42.95
MHz) and externally referenced to K2PtCl4 in water
with downfield chemical shifts reported as positive. The
correct analysis of the ABX spin systems listed in Table
7 has been checked by simulating the spectra using the
gNMR V 3.6 software package (IvorySoft). NMR
spectra were recorded in pure CDCl3, unless otherwise
stated. The reactions were generally monitored by IR
spectroscopy in the n(CO) region. [M(CO)5(h1-dppm)]
2.4. Preparation of [(OC)4W(m-CNCF3)(m-
dppm)Pt(PPh3)] (2)
Compuond 1c (97 mg, 0.079 mmol) was dissolved in
CH2Cl2. CF3NC (0.080 mmol) was added using ‘pVT
vacuum techniques’. The solution was stirred for one
hour at ambient. Afterwards n-pentane was added to
(Mꢁ
[CNCH2PPh3][PF6] and [CNCF3] were prepared as
described in the literature [16ꢀ20], the other isocyanides
were obtained commercially from Fluka or Aldrich.
/Cr,
Mo,
W),
[Pt(CH2CH2)(PPh3)2],
precipitate the product in form of yellowꢀorange
/
crystals, which were collected by filtration. Yield: 76%.
Anal. Calc. for C49H37F3NO4P3PtW (1232.65): C,
47.74; H, 3.03; N, 1.14. Found: C, 47.98; H, 3.09; N,
/

218
M. Knorr et al. / Journal of Organometallic Chemistry 684 (2003) 216ꢀ229
/
1.01%. IR (KBr): n(CO): 2021s, 1959m, 1928s, 1898vs;
2.9. Preparation of [(benzylNC)(OC)3W(m-CO)(m-
dppm)Pt(PPh3)](5) and of cis-
[(benzylNC)(OC)4W(h1-dppm)] (8a)
1
n(CÄ
2H, 2JP,H
35H, phenyl).
/
N) 1620m cmꢃ1. H-NMR: dꢁ
/
4.62 (dt, PCH2,
ꢁ
/
8.9 and 1.5, 3JPt,H
ꢁ
/
42.0 Hz), 6.86ꢀ
/7.49 (m,
Complex 5 was prepared as described for 3a and
isolated as orangeꢀred powder. Since the crude product
contained ca. 10% of 8a as impurity, no correct
elemental analysis could be obtained. IR (CH2Cl2):
/
2.5. Preparation of [(OC)4Cr(m-CNCH2SO2p-
tolyl)(m-dppm)Pt(PPh3)] (3a)
n(CN) 2148m; n(CO): 2014s, 1920sh, 1902vs; n(CÄ
1786m cmꢃ1. 1H-NMR: dꢁ4.45 (t, PCH2, 2H, 2JP,H
9.2 Hz), 5.13 (m, 2H, NCH2), 6.86ꢀ7.49 (m, 40H,
phenyl). During attempts of purification, further frag-
mentation occurred. Among the degradation products,
yellow air-stable 8a co-crystallized. Suitable crystals for
/
O)
Solid p-tosylmethylisocyanide (98 mg, 0.5 mmol) was
added in three portions to a solution of 1a (559 mg, 0.5
mmol) in 10 ml of CH2Cl2. After being stirred for 30
min, the solution was concentrated to ca. 5 ml, layered
/
ꢁ
/
/
with hexane, and stored at ꢃ
/
25 8C. Yellowꢀorange
/
microcrystals of 3a were formed, which were collected
after 2 days and dried under vacuo (355 mg, 59% yield).
Anal. Calc. for C56H46CrNO6P3PtS (1201.06): C, 56.00;
H, 3.86; N, 1.17 Found: C, 55.55; H, 3.61; N, 1.04%. IR
X-ray diffraction were grown from CHCl3ꢀheptane.
/
Anal. Calc. for C37H29NO4P2W (797.44): C, 55.73; H,
3.66; N, 1.76 Found: C, 54.79; H, 3.79; N, 1.83%. IR
(CH2Cl2): n(CN) 2147m; n(CO): 2012s, 1931s, 1906vs
(KBr): n(CO): 1987s, 1923vs, 1890s; n(CÄ
/
N) 1667m
1
2
cmꢃ1. H-NMR: dꢁ
and 1.2 Hz), 4.34 (m, 2H, NCH2), 6.88ꢀ
phenyl). 13C{1H}-NMR: dꢁ
47.3 (t, PCH2, JP,c
/
3.27 (dd, PCH2, 2H, JP,H
ꢁ7.5
/
1
cmꢃ1. H-NMR: dꢁ
/
2.33 (s, CH3, 3H), 4.35 (t, PCH2,
2
2H, JP,H
3
9.4, JPt,H
7.42 (m, 39H, phenyl).
/
7.38 (m, 25H,
ꢁ
/
ꢁ41.0 Hz), 5.06 (s, br NCH2,
/
1
/
ꢁ37
/
2H), 6.80ꢀ
/
Hz), 138.3 (s, vbr, CH2), 152.7 (s, vbr, CN), 199.8 (dd,
2JP,c
4
7, JP,c
2COcis
,
6, JP,c
ꢁ
/
ꢁ
/
2 Hz), 202.6 (dd, 1COcis,
2JP,c
2.6. Preparation of [(OC)4Mo(m-CNCH2SO2p-
tolyl)(m-dppm)Pt(PPh3)] (3b)
4
2JP,c
Hz).
ꢁ
/
ꢁ
/
2 Hz), 203.9 (d, 1COtrans
,
ꢁ
/
25
This complex was prepared as described for 3a (474
+
2.10. Preparation of [(cyclohexylNC)(OC)3W(m-
CO)(m-dppm)Pt(PPh3)](6) and of cis-
mg, 69% yield). Anal. Calc. for C56H46MoNO6P3PtS
1.5 CH2Cl2 (1201.06ꢂ127.39): C, 50.32; H, 3.60; N, 1.02
/
[(cyclohexyllNC)(OC)4W(h1-dppm)] (8b)
Found: C, 50.02; H, 3.78; N, 1.01%. IR (KBr): n(CO):
2009s, 1930sh, 1902vs; n(CÄ
dꢁ
3JPt,H
39H, phenyl).
/
N) 1680m cmꢃ1. 1H-NMR:
Complex 6 was prepared as described for 5 and
isolated as an orangeꢀred powder. Since the crude
product contained ca. 20% of 8b as impurity, no correct
2
/
2.27 (s, CH3, 3H), 4.26 (t, PCH2, 2H, JP,H
ꢁ/9.6,
/
ꢁ
/
39.0 Hz), 4.90 (s, br NCH2, 2H), 6.76ꢀ
/
7.43 (m,
elemental analysis could be obtained. IR (CH2Cl2):
n(CN) 2144m; n(CO): 2013s, 1901vs, 1882sh; n(CÄ
1792m cmꢃ1 1H-NMR: dꢁ
1.28ꢀ1.62 (m, 11H,
C6H11), 4.52 (t, PCH2, 2H, JP,H
Hz), 6.86ꢀ7.49 (m, 50H, phenyl).
Compound 8b: IR (CH2Cl2): n(CN) 2144m; n(CO):
2013s, 1931s, 1906vs cmꢃ1 1H-NMR: dꢁ
1.29ꢀ1.61
(m, 11H, C6H11), 3.33 (dd, PCH2, 2H, JP,H 7.3 and
1.2 Hz), 6.90ꢀ7.68 (m, 20H, phenyl).
/
O)
2.7. Preparation of [(OC)4W(m-CNCH2SO2p-tolyl)(m-
dppm)Pt(PPh3)] (3c)
.
/
/
2
3
ꢁ
/
8.4, JPt,H
ꢁ
/
32
/
This complex was prepared as described for 3a (473
mg, 71% yield). Anal. Calc. for C56H46NO6P3PtWS
(1332.91): C, 50.46; H, 3.48; N, 1.05 Found: C, 50.67; H,
3.84; N, 1.07%. IR (KBr): n(CO): 2007s, 1919sh, 1894vs;
.
/
/
2
ꢁ
/
/
n(CÄ
4.49 (t, PCH2, 2H, 2JP,H
br NCH2, 2H), 6.80ꢀ7.42 (m, 39H, phenyl).
/
N) 1654m cmꢃ1. 1H-NMR: dꢁ
/
2.37 (s, CH3, 3H),
ꢁ
/
9.4, 3JPt,H
ꢁ
/41.0 Hz), 4.99 (s,
2.11. Preparation of [(OC)3Fe{m-CÄ
/
Nꢀ
/
/
CH2PO(OEt)2}(m-dppm)Pt(PPh3)] (9)
2.8. Preparation of [(OC)4W(m-CNCH2PPh3)(m-
dppm)Pt(PPh3)][PF6] (4)
To a solution of [(OC)3Fe(m-CO)(m-dppm)Pt(PPh3)]
(505 mg, 0.5 mmol) in 10 ml of dichloromethane was
added dropwise CNCH2PO(OEt)2 (80 ml, 0.5 mmol) by
means of a micro-syringe. The orange reaction mixture
was stirred at room temperature for 30 min and then
concentrated to ca. 4ml under reduced pressure. Addi-
tion of a hexane layer gave after 2 days in a refrigerator
large orange crystals solvated with dichloromethane
This complex was prepared as described for 3a (474
mg, 61% yield). Anal. Calc. for C67H54NO4P3PtW×
/PF6
(1554.01): C, 51.79; H, 3.50; N, 0.90 Found: C, 51.39; H,
3.31; N, 0.84%. IR (KBr): n(CO): 2011s, 1929s, 1896vs;
1
n(CÄ
/
N) 1622m cmꢃ1. H-NMR: dꢁ
/
4.61 (dt, PCH2,
2
2H, JP,H
3
9.2 and 1.5, JPt,H
ꢁ
/
ꢁ/27.5 Hz), 5.13 (m, 2H,
(478
mg,
77%
yield).
Anal.
Calc.
84.93): C, 51.18;
for
NCH2), 6.86ꢀ/7.49 (m, 50H, phenyl).
C52H49FeNO6P4Pt×
/
CH2Cl2 (1158.79ꢂ
/

M. Knorr et al. / Journal of Organometallic Chemistry 684 (2003) 216ꢀ
/229
219
H 4.13; N, 1.13. Found: C, 50.98; H 4.55; N, 1.24%. IR
(KBr): n(CO): 1994s, 1923vs, 1904sh; n(CÄN) 1648m
cmꢃ1. 1H-NMR: dꢁ1.07 (t, CH3, 6H, 2JH,H
7.0 Hz),
3.85 (m, OCH2, 4H and PCH2, 2H), 4.22 (d, NCH2, 2H,
2JP,H
13.1 Hz), 7.11ꢀ7.35 (m, 35H, phenyl).
intensities of three standard reflections, which were
measured after every 100 reflections, remained stable
throughout each data collection. The intensities were
corrected for Lorentz and polarization effects. An
empirical absorption correction based on the C-scans
of three reflections was employed. Data of 1a,c and 8a
were collected on a Stoe IPDS diffractometer. The
intensities were determined and corrected by the pro-
gram INTEGRATE in IPDS (Stoe & Cie, 1999). An
empirical absorption correction was employed using
the FACEIT-program in IPDS (Stoe & Cie, 1999).
/
/
ꢁ
/
ꢁ
/
/
2.12. Preparation of [(OC)4W(m-CÄ
/N(H)CF3)(m-
dppm)Pt(PPh3)][BF4] (10)
To a solution of 2 (10 mg) in 2 ml of dichloromethane
was added a drop of HBF4×Et2O. All volatiles were
/
removed under vacuo. NMR examination of the yellow
residue indicated quantitative formation of 10. The
FABꢂ mass spectrum (NBA matrix) exhibits with
100% intensity the peak for the cation at m/z 1234,
whose experimental isotope distribution pattern
matches with the simulated one. IR (KBr): n(CO):
The structures were generally solved by direct and
Fourier methods using SHELXS-97. For each structure,
the non-hydrogen atoms were refined anisotropically.
All of the H-atoms were placed in geometrically
calculated positions and each was assigned a fixed
isotropic displacement parameter based on a riding-
model.. Refinement of the structures was carried out by
full-matrix least-squares methods based on F2o using
SHELXL-97. All calculations were performed using the
WINGX crystallographic software package, using the
programs SHELXS-97 and SHELXL-97 [22]. The crystal-
lographic data for each complex are given in Table 8.
2062s, 1981m, 1944vs cmꢃ1
.
1H-NMR: dꢁ
24.0 Hz), 6.50ꢀ
(m, 35H, phenyl), 8.45 (m, br, CNH, 1H).
/
5.30 (t,
2
3
PCH2, 2H, JP,H
ꢁ
/
10.0, JPt,H
ꢁ
/
/
7.65
2.13. Preparation of [(OC)4Mo(m-CÄ
/N(H)CH2SO2p-
tolyl)(m-dppm)Pt(PPh3)][BF4] (11)
This complex was prepared by addition of an excess
of HBF4×Et2O at 253 K to a solution of 3b (125 mg, 0.1
/
3. Results and discussion
mmol) in CH2Cl2 (5 ml). After stirring for 10 min, all
volatiles were removed under reduced pressure. The
yellow residue was rinsed with Et2O (2ml) and then
dried under vacuo (133 mg, 94% yield). Anal. Calc. for
3.1. Syntheses and characterisation of [(OC)4M
(m-CÄ
/
O)(m-dppm)Pt(PPh3)]
C56H47MoNO6P3PtBF4×
48.29; H 3.48; N, 0.99. Found: C, 48.56; H 3.68; N,
1.06%. IR (CH2Cl2): n(CO): 2051s, 2005m, 1946vs
/
CH2Cl2 (1332.81ꢂ84.93): C,
/
In order to evaluate also the influence of the bridging
diphosphane backbone on the outcome of the reaction
of [(OC)4M(m-CÄ
/
O)(m-Ph2PXPPh2)Pt(PPh3)] (Xꢁ
/NH,
1
cmꢃ1. H-NMR: dꢁ
/
2.41 (s, CH3, 3H), 4.73 (t, PCH2,
10.0, JPt,H 21.0 Hz), 4.95 (d, NCH2, 2H,
5.9 Hz), 6.6ꢀ7.65 (m, 39H, phenyl), 8.16 (m, br,
CNH, 1H).
CH2) with CNR, we have choosen dppm as dipho-
sphane backbone. This ligand is known to be more
electron-donating compared to dppa (see below). To
2
3
2H, JP,H
ꢁ
/
ꢁ
/
3JP,H
ꢁ
/
/
allow a comparison with some recently prepared Feꢀ
isocyanide complexes, we furthermore extended our
study to CrꢀPt complexes. The hitherto unknown
complexes [(OC)4M(m-CÄO)(m-dppm)Pt(PPh3)] (1aꢀc)
were obtained by reaction of M(CO)5(h1-dppm)] (Mꢁ
Cr, Mo, W) with [Pt(CH2CH2)(PPh3)2] in toluene with
70ꢀ85% yield. The yellowꢀorange compounds, which
/
Pt
2.14. Crystal structure determinations
/
/
/
A crystal of compound 2 was mounted on the top of a
glass fibre and brought immediately into the cold gas
stream of a Bruker-AXS Smart 1000 diffractometer.
Data of 2 were collected at 153(2) K. A total of 4200
/
/
/
are insoluble in hexane or Et2O, are air stable as solids
but gradually decompose in halogenated solvents
(Scheme 1).
frames were recorded by v-scans (Dvꢁ0.38, 30 s) at
/
seven different f positions. The intensities were deter-
mined and corrected by the program SAINT (area-
detector integration software; Siemens Industrial Auto-
mation Inc., Madison, WI, 1995). An empirical absorp-
tion correction
(SADABS, area-detector absorption
correction; Siemens Industrial Automation Inc., Madi-
son, WI, 1996) was employed using the multiscan
method [21]. Data of 3c and 9 were collected on a
Siemens AED2 diffractometer using graphite-mono-
˚
Ka radiation (lꢁ0.71069 A). The
chromated Moꢀ
/
/
intensities were collected using V ꢀ
/
2u scans, and the
Scheme 1.

220
M. Knorr et al. / Journal of Organometallic Chemistry 684 (2003) 216ꢀ229
/
3.1.1. Spectroscopic data
The 31P{1H}-NMR spectra of 1aꢀ
m-C 199.2(7) pm], the asymmetry of 1a with angles Crꢀ
C(1)ꢀO(1) and PtꢀC(1)ꢀO(1) of 128.1(3) and 152.0(3)8
is evident. The above mentioned compounds [(Me3-
/
/
c consist of three
/
/
/
mutually coupled doublet of doublets (Table 7).
Whereas in the case of 1a the three resonances at d
55.9 (P1Cr), 45.1(PPh33Pt) and 10.1(P2Pt) are quite
distinct, the resonances of P1 and P2 approach in the
case of 1b and give finally rise to an ABX spin system in
the case of 1c, the AB part being centred at d 13.0 ppm.
The chemical shift of the Pt signal in the 195Pt{1H}-
P)(OC)3Cr(m-CÄ
/
O){m-C(CO2Me)}Pt(PMe3)2]
and
possess
[(OC)4Cr(m-CÄ
/
O)(m-PPh2)Pt(h3-cycloctenyl)]
also asymmetric bridging carbonyls, but in both cases
the Ptꢀm-C bonds are significantly longer [219.3(0) and
225.2(7) pm] than the Crꢀm-C bonds [175.0(5) and
197.6(7) pm] (Chart 1).
The ligand arrangement of 1c is very similar to that of
1a. The adjacent metals are connected via WꢀPt bond,
the distance of 287.6(3) pm being quite close to that of
[(HBpz3)(OC)W(m-CÄ
O){m-h1-h2-
C(H)(NEt2)}Pt(PEt3)2][BF4] [287.1(10) pm] and
[(PPh3)(OC)3W(m-CÄO){m-P(Ph)(C5H4C5H4)}Pt(PPh3)]
[291.56(1) pm] [28,29]. Again, a carbonyl ligand bridges
in an asymmetric manner the metalꢀmetal bond. In
spite of the very similar atomic radii of W and Pt ( 1.30
/
/
NMR spectra of 1aꢀ
of the adjacent metal centre (d 1a ꢃ
1c ꢃ2484.0). In the case of 1b,c the signal is splitted in
/c is not much affected by the nature
/
2431.5, 1b ꢃ2514.5,
/
/
/
the expected doublet of doublet of doublets pattern due
a coupling with three phosphorous nuclei, whereas in
the case of 1a (and 3a) the 2ꢂ3JPt,P coupling is probably
/
/
to weak to be observed. The IR spectra of 1a
/c show in
ꢀ
addition to three terminal n(CO) stretches a vibration at
1789 (1a), 1800 (1b) and 1781 (1c) cmꢃ1 for a
(semi)bridging carbonyl ligand. These positions are
between those found for genuine m(CO) vibrations
/
˚
A), the Wꢀ
/
C(1) distance [241.8(8) pm] is significantly
C(1) distance
longer than the corresponding Ptꢀ
/
(e.g. [(OC)3Fe(m-CÄ
[23] and typical semi-bridging vibrations (e.g. [(Me3-
1833
cmꢃ1
/
O)(m-dppm)Pt(PPh3)] 1760 cmꢃ1
)
[192.3(10) pm] (Fig. 2a,b). This contrasts again with
the (semi)bridging CO bonding mode reported for
P)(OC)4Cr(m-CPh)Pt(PMe3)2][BF4]
;
[(HBpz3)(OC)W(mꢀ
C(H)(NEt2)}Pt(PEt3)2][BF4] and [(PPh3)(OC)3W(m-CÄ
O){m-P(Ph)(C5H4C5H4)}Pt(PPh3)], where the Ptꢀm-C
bonds are by far longer [228.0(2) and 243.1(3) pm]
than the Wꢀm-C bonds [208.0(4) and 202.0(3) pm].
[28,29] In the case of the dppm-spanned compound
[Cp(OC)2W(m-dppm)Pt(h1-dppm)][PF6]
[d WꢀPt
290.2(2) pm] possessing a slightly semi-bridging carbon-
yl, the Ptꢀm-C contact is still weaker [261.2(2) pm]. [25b]
/
CÄ
/
O){m-h1-h2-
[Cp(OC)3MoPt(H)(PPh3)2] 1820 cmꢃ1; [Cp(OC)2W(m-
dppm)Pt(h1-dppm)][PF6] 1797 cmꢃ1). [24,25a,b] The
molecular structures of 1a and 1c have been determined
to (i) clarify the kind of bridging interaction between M
and Pt and (ii) to allow a structural comparison of the
CO-bridged starting materials with their m-CNR coun-
terparts (see below).
/
/
/
/
/
3.1.2. Crystal structures of [(OC)4M(m-CÄ
dppm)Pt(PPh3)] (1a and 1c)
Suitable crystals of 1a and 1c for an X-ray diffraction
study were grown from toluene/heptane and CH2Cl2ꢀ
heptane, respectively. The molecular structures are
depicted in Figs. 1 and 2a,b, selected bond lengths and
angles are given in Tables 1 and 2. The coordination
around chromium of 1a is best described as distorted
/O)(m-
At present, we are however unable to give a rationalisa-
tion for the structural features of compounds 1, some
future theoretical calculations seem necessary for an
understanding of the electronic structure of these
heterometallic systems.
/
3.2. Syntheses and characterisation of [(OC)4M(mꢀ
N-R)(m-dppm)Pt(PPh3)]
/
CÄ
/
octahedral with an additional metalꢀ
ing the angle between C(4) and C(5), thus being seven-
coordinate. The CrꢀPt distance of 277.49(8) pm lies
half-way between that reported for [(Me3P)(OC)3Cr(m-
CÄO){m-C(CO2Me)}Pt(PMe3)2] [266.6(7) pm] and
[(OC)4Cr(m-CÄ
/
metal bond bisect-
The reaction of 1c in dichloromethane at ambient
temperature with the strong p-accepting isocyanides
CNCF3, CNCH2SO2p-tolyl and [CNCH2PPh3][PF6]
gave within 10 min exclusively the bright yellow com-
/
/
/
O)(m-PPh2)Pt(h3-cycloctenyl)] [282.0(1)
pm] [24,26]. The two metal centres are spanned by the
plexes [(OC)4W(m-CÄ
and 4) by substitution of the bridging carbonyl ligand
according Scheme 2. In similar manner, the orangeꢀ
yellow compounds [(OC)4Cr(m-CÄNꢀCH2SO2p-to-
Nꢀ
/
NꢀR)(m-dppm)Pt(PPh3)] (2, 3c
/
diphosphane-ligand forming a distorted five-membered
/
ring with an torsion angle P(1)ꢀ
addition, the CrꢀPt bond is bridged asymmetrically by a
carbonyl ligand with very long CrꢀC(1) bond [238.9(4)
pm] and a short PtꢀC(1) bond [190.4(4) pm]. This
semi(bridging) bonding situation needs some comment:
/
Crꢀ
/
PtꢀP(2) of 34.48. In
/
/
/
/
lyl)(m-dppm)Pt(PPh3)] (3a) and [(OC)4Mo(m-CÄ
/
/
/
CH2SO2p-tolyl)(m-dppm)Pt(PPh3)] (3b) were formed
/
compared with Shaw’s compound [(OC)3Fe(m-CÄO)(m-
/
dppm)Pt(PPh3)] [27] (the van der Waals radii of Cr and
Fe are approximately comparable) possessing a symme-
Chart 1.
trically bridging m-CO ligand [Feꢀ
/
m-C 201.2(7) pm; Ptꢀ
/

M. Knorr et al. / Journal of Organometallic Chemistry 684 (2003) 216ꢀ
/229
221
Fig. 1. View of the molecular structure of 1a with the numbering scheme.
upon stoichiometric treatment of 1a,b with tosylmethy-
lisocyanide. All derivatives are stable as solids at least
for some weeks, but gradually decompose in haloge-
nated solvents. Again, the three phosphorous nuclei of
frequencies with respect to their dppa-counterparts.
Indicative for the bridging bonding mode of the CNR
ligand is the presence of a n(CÄ
/
N) vibration of medium
1680 cmꢃ1. Within
c, the position of this vibration is quite
intensity in the range between 1620ꢀ
/
Wꢀ
/
Pt core give rise to ABX spin systems in the 31P-
the series 3a
/
ꢀ
NMR spectra (Table 7). In addition, each of the 4 visible
lines of the X-part of 2 are further splitted into a
5
quadruplet due to a weak JP,F coupling with the CF3
close in the case of the Crꢀ
/
Pt and MoꢀPt derivatives
/
(1672 vs. 1679 cmꢃ1), but is shifted to lower wave
numbers for the Wꢀ
/
Pt analogue (1655 cmꢃ1). The
particular low frequency in the case of 2 compared to 3c
substituent. The stronger donor character of dppm
compared with dppa can be inferred from the IR
spectra, since the position of the carbonyl bands of
3b,c is shifted approximately 10 wave-numbers to lower
(1620 vs. 1655 cmꢃ1) is coherent with the elongation of
the CÄ
/
N bond length observed in the crystal structures
of those complexes (see below).
Scheme 2.

222
M. Knorr et al. / Journal of Organometallic Chemistry 684 (2003) 216ꢀ229
/
Fig. 2. (a) View of the molecular structure of 1c with the numbering scheme. (b) Perspective view of the core structure of 1c along the Ptꢀ
/W bond.
The phenyl groups are omitted for clarity.
3.2.1. Crystal structures of [(OC)4W(m-CÄ
/
Nꢀ
/
R)(m-
to that of 1c and parallels that reported for [(OC)5W(m-
dppm)Pt(PPh3)] (2 and 3c)
Suitable crystals of 2 for an X-ray diffraction study
were grown from CH2Cl2ꢀheptane at ꢃ30 8C. The
CÄ
P(1)ꢀ
with the dppm-backbone is less distorted (34.258) than
that of 1c (39.158). As for 1c, the WꢀPt bond is bridged
asymmetrically by the organic ligand by a long Wꢀm-C
bond and a short Ptꢀm-C bond. The degree of asym-
metry is, however, less pronounced, since the WꢀC(1)
distance is now remarkably shorter [225.4(4) vs. 241.8(8)
pm], whereas the PtꢀC(1) separation has increased by
ca. 5 pm [196.9(4) vs. 192.3(10) pm]. Compared with the
/
CH2)Pt(dppm)] [277.4(1) pm] [30]. The torsion angle
/
Wꢀ
/
PtꢀP(2) of the five-membered ring formed
/
/
/
molecular structure is depicted in Fig. 3, selected bond
lengths and angles are given in Table 3. The overall
geometries of 2 and 3c are quite related to that of their
precursor 1c. Thus, the coordination around the tung-
sten centre of 2 is also seven-coordinate due to presence
/
/
/
/
of a Wꢀ
/
Pt bond. The Wꢀ/Pt distance of 279.07(4) pm
/
has however significantly shrunk about 8 pm compared

M. Knorr et al. / Journal of Organometallic Chemistry 684 (2003) 216ꢀ
/229
223
Table 1
Selected bond lengths (pm) and bond angles (8) for 1a
parallel to the WꢀPt axis. The Pt atom is present in a
distorted square planar environment, the root mean
square deviation from the plane defined by Pt, W, P(2),
/
Bond lengths
˚
P(3) and C(1) being 0.055 A. An electronic description
Crꢀ
Ptꢀ
Ptꢀ
Ptꢀ
Crꢀ
Crꢀ
/
Pt
277.49(8)
229.73(9)
233.49(12)
190.4(4)
Crꢀ
Crꢀ
Crꢀ
Crꢀ
/
C(2)
C(3)
C(4)
C(5)
184.2(4)
186.1(4)
190.8(4)
188.2(4)
118.2(5)
for the bimetallic system consisting in a 18-electron
count for the tungsten centre and a 16-electron config-
uration for the Pt8 centre seems appropriate. The
molecular structure of 3c (see Fig. 4 and Table 4)
/
P(3)
P(2)
C(1)
/
/
/
/
/
/P(1)
238.36(12)
238.9(4)
C(1)ꢀO(1)
/
/C(1)
corresponds to that reported for [(OC)4W(m-CÄ
/
Nꢀ
/
Bond angles
C(2)ꢀCrꢀC(5)
P(1)ꢀC(18)ꢀP(2)
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
CrꢀPtꢀ
CrꢀPtꢀ
P(1)ꢀ
PtꢀC(5)ꢀ
CrꢀC(5)ꢀ
CH2SO2p-tolyl)(m-dppa)Pt(PPh3)] and deserves no
further comments. [15] The separation of the two metal
centres of 283.87(6) pm is somewhat more important
than that of its dppa-bridged analogue [281.0(2) pm]
and that of 2, but inferior to that of 1c.
/
/
88.46(17)
107.35(18)
89.82(11)
178.28(13)
109.08(10)
89.94(11)
89.86(11)
157.83(3)
97.82(3)
P(2)ꢀ
PtꢀC(1)ꢀ
PtꢀCrꢀC(1)
C(1)ꢀCrꢀ
C(3)ꢀCrꢀ
C(2)ꢀCrꢀ
C(3)ꢀCrꢀ
C(2)ꢀCrꢀ
C(3)ꢀCrꢀ
C(1)ꢀCrꢀ
C(2)ꢀCrꢀ
/
Ptꢀ
/
P(3)
104.34(4)
79.66(14)
42.46(10)
77.93(15)
72.62(15)
88.60(16)
90.78(17)
89.40(17)
89.36(17)
177.86(16)
156.42(16)
/
/
/
/
Cr
/
Crꢀ
Crꢀ
Crꢀ
Crꢀ
Crꢀ
/
C(2)
C(3)
C(1)
C(4)
C(5)
/
/
/
/
/
/
C(5)
C(1)
C(3)
C(5)
C(4)
C(4)
C(4)
C(5)
/
/
/
/
/
/
/
/
/
/
/
/
/
/
P(3)
/
/
3.3. Syntheses and characterisation of
[(OC)3(RNC)M(m-CO)(m-dppm)Pt(PPh3)]
/
/
P(2)
/
/
/Crꢀ
/Pt
79.19(3)
152.0(3)
/
/
/
/
O(5)
/
/
The site selectivity of the carbonyl substitution by
CNR seems to depend in a very sensitive manner on the
nucleophilic character of the iscocyanide ligand. Upon
stoichiometric reaction of 1c with benzylisocyanide,
/
/O(5)
128.1(3)
Table 2
Selected bond lengths (pm) and bond angles (8) for 1c
exclusively the complex [(BzNC)(OC)3W(m-CÄO)(m-
/
dppm)Pt(PPh3)] (5) ligated by a terminal isonitrile on
tungsten is formed according the IR and NMR data.
The conservation of the bridging carbonyl is evidenced
Bond lengths
Wꢀ
Ptꢀ
Ptꢀ
Ptꢀ
Wꢀ
Wꢀ
/
Pt
287.6(3)
229.9(4)
233.6(3)
192.3(1)
250.2(3)
241.8(8)
Wꢀ
Wꢀ
Wꢀ
Wꢀ
/
C(2)
C(3)
C(4)
C(5)
205.1(9)
199.0(10)
198.7(9)
203.8(10)
117.8(11)
by the observation of a m(CÄ
the presence of an terminal isocyanide ligand is indi-
N) stretch of medium intensity at 2148
/
O) stretch at 1786 cmꢃ1
,
/
P(3)
P(2)
C(1)
/
/
/
/
/
cated by a m(CÅ
/
/P(1)
C(1)ꢀO(1)
/
cmꢃ1. Chemical shifts and coupling constants of the
ABX system in the 31Pt{1H}-NMR and the doublet of
doublet of doublets pattern in the 195Pt{1H}-NMR
spectra are quite close to that of the precursor 1c. The
outcome of the reaction with cyclohexyl isocyanide is
identical (Scheme 2). Even with diethyl(isocyano-
methyl)phosphonate, which can not be considered as
strong nucleophilic isocyanide, the teminal bonding
mode of CNCH2PO(OEt)2 is encountered giving
/C(1)
Bond angles
C(2)ꢀWꢀC(1)
P(1)ꢀC(18)ꢀP(2)
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
WꢀPtꢀ
WꢀPtꢀ
P(1)ꢀ
PtꢀC(1)ꢀ
WꢀC(1)ꢀ
/
/
75.2(3)
111.2(4)
93.9(3)
P(2)ꢀ
PtꢀC(1)ꢀ
PtꢀWꢀC(1)
C(1)ꢀWꢀ
C(3)ꢀWꢀ
C(2)ꢀWꢀ
C(3)ꢀWꢀ
C(2)ꢀWꢀ
C(3)ꢀWꢀ
C(1)ꢀWꢀ
C(2)ꢀWꢀ
/
Ptꢀ
/
P(3)
108.85(11)
82.1(3)
41.5(2)
111.5(3)
87.4(4)
92.4(4)
75.7(3)
85.7(4)
88.1(4)
154.1(4)
172.9(3)
/
/
/
/
W
/
Wꢀ
Wꢀ
Wꢀ
Wꢀ
Wꢀ
/
C(2)
C(3)
C(4)
C(1)
C(5)
/
/
/
/
173.3(3)
90.2(3)
/
/
C(5)
C(5)
C(3)
C(1)
C(4)
C(4)
C(4)
C(5)
/
/
/
/
/
/
108.1(3)
86.1(3)
/
/
/
/
/
/
/
/
P(3)
155.21(7)
95.93(10)
77.61(10)
149.8(7)
128.0(7)
/
/
/
/
P(2)
/
/
[{(EtO)2OPCH2NC}(OC)3W(m-CÄ
dppm)Pt(PPh3)] (7a).
Unfortunately, the stability of 5ꢀ
/
O)(m-
/Wꢀ
/Pt
/
/
/
/O(1)
/
/
/7 in solution is
/
/O(1)
limited due to progressive fragmentation into mono-
nuclear fragments. Therefore, no single crystals for X-
ray diffraction studies or correct elemental analyses
could be obtained. However, the formation of 7a was
furthermore ascertained by a FABꢂ mass spectrum of
the crude product displaying a peak at m/z 1314 with
lengths of the C(1)ꢀ
/
N double bond of 3c, the C(1)ꢀN
/
double bond of 2 is somewhat longer [123.9(9) vs.
124.7(5) pm]. This lengthening is probably based on
the stronger electron-withdrawing propensity of CF3
compared to CH2ꢀ
acceptor behaviour of CNCF3 based on back-bonding
into its p* orbitals. A comparable lengths of the CÄ
bond [124.0(3) pm] has been encountered in the tri-
nuclear cluster [Os3(CO)10(m-CÄNꢀCF3)]. [31] As al-
ready observed for Nꢀtosyl)(m-
[(OC)4W(m-CÄ
dppa)Pt(PPh3)], the C(1)ꢀNꢀC(2) angle is strongly
bent [128.5(4)8], the C(1)ꢀNꢀCF3 unit being aligned
/
tosyl, consistent with the excellent p-
/
N
/
/
/
/
/
/
Scheme 3.
/
/

224
M. Knorr et al. / Journal of Organometallic Chemistry 684 (2003) 216ꢀ
/229
Scheme 4.
24% intensity, whose experimental isotope distribution
pattern matched well with the simulated one. Among the
mononuclear fragments formed during the degradation,
dral complex, whose overall structure is comparable
with that of [(OC)5W(h1-dppm)] [18]are given in Table
5.
the
metallophosphine
cis-[(benzylNC)(OC)4W(h1-
dppm)] (8a) crystallized during attempts of recrystallisa-
tion of 5. Formation of cis-[(cyclohexylNC)(OC)4W(h1-
dppm)] (8b) was also observed during the synthesis of 6.
3.4. Syntheses and characterisation of [(OC)3Fe){m-CÄ
/
Nꢀ
/
CH2PO(OEt)2}(m-dppm)Pt(PPh3)]
The yellowꢀorange complex 8a was completely char-
acterized by multinuclear NMR and IR spectroscopy. In
addition, the cis-arrangement between P(1) and C(5) of
/
For comparison, we reacted also [(OC)3Fe(m-CÄ
/
O)(m-
dppm)Pt(PPh3)] with CNCH2PO(OEt)2 in dichloro-
methane at ambient temperature (Scheme 3). It seems
the linear isocyanide ligand [C(5)ꢀ
/
NꢀC(6) 179.0(2)8]
/
that the FeꢀPt system is much more insensitive with
/
was confirmed by an X-ray diffraction study (Fig. 5).
Further selected bond length and angles of this octahe-
respect to the electronic properties of the CNR ligand,
since in contrast to 6, the isocyanide ligand of
Fig. 3. View of the molecular structure of 2 with the numbering scheme.

M. Knorr et al. / Journal of Organometallic Chemistry 684 (2003) 216ꢀ
/229
225
Table 3
Selected bond lengths (pm) and bond angles (8) for 2
Table 4
Selected bond lengths (pm) and bond angles (8) for 3c
Bond lengths
Bond lengths
Wꢀ
Ptꢀ
Ptꢀ
Ptꢀ
Wꢀ
Wꢀ
/
Pt
279.07(4)
226.98(11)
231.74(11)
196.9(4)
Wꢀ
Wꢀ
Wꢀ
Wꢀ
/
C(2)
C(3)
C(4)
C(5)
202.3(5)
199.6(6)
200.0(5)
205.0(6)
124.7(5)
Wꢀ
Ptꢀ
Ptꢀ
Ptꢀ
Wꢀ
Wꢀ
/
Pt
283.87(6)
227.89(19)
232.04(18)
194.6(7)
Wꢀ
Wꢀ
Wꢀ
Wꢀ
/
C(10)
C(11)
C(12)
C(13)
199.3(10)
/
P(3)
P(2)
C(1)
/
/
P(3)
P(2)
C(1)
/
201.5(9)
199.4(9)
203.7(9)
123.7(9)
/
/
/
/
/
/
/
/
/P(1)
251.20(11)
225.4(4)
C(1)ꢀ
/
N
/P(1)
250.8(2)
231.2(7)
C(1)ꢀN
/
/C(1)
/C(1)
Bond angles
C(2)ꢀWꢀC(1)
P(1)ꢀC(18)ꢀP(2)
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
WꢀPtꢀ
WꢀPtꢀ
P(1)ꢀ
PtꢀC(1)ꢀ
WꢀC(1)ꢀ
Bond angles
C(1)ꢀWꢀC(13)
P(1)ꢀC(26)ꢀP(2)
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
WꢀPtꢀ
WꢀPtꢀ
P(1)ꢀ
PtꢀC(1)ꢀ
WꢀC(1)ꢀ
/
/
81.92(16)
110.6(2)
P(2)ꢀ
PtꢀC(1)ꢀ
PtꢀWꢀC(1)
C(1)ꢀWꢀ
C(3)ꢀWꢀ
C(2)ꢀWꢀ
C(3)ꢀWꢀ
C(2)ꢀWꢀ
C(3)ꢀWꢀ
C(1)ꢀWꢀ
C(1)ꢀNꢀ
/
Ptꢀ
/
P(3)
108.93(4)
82.43(15)
44.39(10)
104.53(18)
86.8(2)
/
/
106.7(3)
110.5(4)
92.3(2)
P(2)ꢀ
PtꢀC(1)ꢀ
PtꢀWꢀC(1)
C(1)ꢀWꢀ
C(1)ꢀWꢀ
C(1)ꢀWꢀ
C(10)ꢀWꢀ
C(10)ꢀWꢀ
C(10)ꢀWꢀ
C(11)ꢀWꢀ
C(1)ꢀNꢀ
/
Ptꢀ
/
P(3)
106.14(7)
83.2(3)
/
/
/
/
W
/
/
/
/
W
/
Wꢀ
Wꢀ
Wꢀ
Wꢀ
Wꢀ
/
C(2)
C(3)
C(4)
C(1)
C(5)
88.28(13)
170.79(17)
87.88(16)
111.40(10)
87.98(15)
148.99(3)
102.01(3)
76.71(2)
/
/
/
Wꢀ
Wꢀ
Wꢀ
Wꢀ
Wꢀ
/
C(11)
C(10)
C(12)
C(1)
/
/
42.88(18)
78.9(3)
76.7(3)
/
/
/
/
C(5)
C(5)
C(3)
C(1)
C(4)
C(4)
C(4)
/
/
169.6(2)
88.6(3)
/
/
C(10)
C(11)
C(12)
/
/
/
/
/
/
/
/
/
/
/
/
96.2(2)
77.30(19)
87.1(2)
/
/
109.58(19)
86.5(2)
/
/
154.2(3)
95.7(3)
/
/
/
/
/
/C(13)
/
/
C(11)
C(12)
C(13)
C(13)
/
/
P(3)
/
/
/
/
P(3)
154.29(5)
99.34(5)
75.75(5)
139.1(6)
137.7(5)
/
/
85.6(4)
85.2(3)
/
/
P(2)
/
/
84.3(42)
157.35(19)
128.5(4)
/
/
P(2)
/
/
/Wꢀ
/Pt
/
/
/
Wꢀ
/Pt
/
/
176.6(3)
126.9(7)
/
/N
132.8(3)
/
/
C(2)
/
/N
/
/
C(2)
/
/N
144.8(3)
/
/N
[(OC)3Fe){m-CÄ
adopts now exclusively a bridging bonding mode, as
indicated by a n(CÄ
N) vibration at 1648 cmꢃ1 in the IR
spectrum of 9. Note that even for the FeꢀPt couple a
terminal CNR bonding mode may be adopted upon
/
Nꢀ
/
CH2PO(OEt)2}(m-dppm)Pt(PPh3)]
treatment with the strong s-donating t-butyl isocya-
nide. [32] This yellow, stable compound was further-
more completely characterized by multinuclear NMR
spectroscopy (Table 7) and an X-ray diffraction study.
/
/
Fig. 4. View of the molecular structure of 3c with the numbering scheme.

226
M. Knorr et al. / Journal of Organometallic Chemistry 684 (2003) 216ꢀ229
/
Fig. 5. View of the molecular structure of 8a with the numbering scheme.
the Ptꢀ
/
m-C(1) distance of 200.1(6) pm is almost identical
Table 5
Selected bond lengths (pm) and bond angles (8) for 8a
with the Feꢀm-C(1) distance of 200.6(6) pm resulting in
a symmetric spanning of the two metals by the ligand.
/
Bond lengths
Due to the octahedral environment around Fe, the five-
Wꢀ
Wꢀ
Wꢀ
Wꢀ
/
P(1)
C(1)
C(2)
C(3)
252.4(2)
207.8(8)
200.9(8)
203.2(8)
Wꢀ
/
C(4)
206.9(8)
213.3(8)
111.7(10)
membered ring formed by P(1)ꢀ
/
C(22)ꢀ
/
P(2)ꢀ
/
PtꢀFe is
/
/
Wꢀ
/
C(5)
quite plane, the torsion angle P(1)ꢀ
/
Feꢀ
/
Pt P(2) being
/
C(5)ꢀN
/
/
6.838.
Bond angles
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
/
Wꢀ
Wꢀ
Wꢀ
Wꢀ
/
C(1)
C(2)
C(3)
C(4)
89.9(2)
176.5(2)
90.7(2)
92.0(2)
P(1)ꢀ
C(5)ꢀ
P(1)ꢀC(25)ꢀ
/
Wꢀ
/
C(5)
C(6)
P(2)
87.0(2)
179.0(2)
110.3(4)
/
/
/
Nꢀ
/
/
/
/
/
/
/
Table 6
Selected bond lengths (pm) and bond angles (8) for 9
3.4.1. Crystal structure of [(OC)3Fe{m-CÄ
CH2PO(OEt)2}(m-dppm)Pt(PPh3)] (9)
Suitable crystals of 9 were grown from CH2Cl2ꢀ
heptane. The molecular structure is depicted in Fig. 6,
selected bond lengths and angles are given in Table 6.
Since the overall geometry of 9 is quite reminiscent to
that of the benzyl- and xylylisocyanide bridged deriva-
tives (obtained by other synthetic methods), only the
most pertinent structural features will be discussed
/
Nꢀ
/
Bond lengths
/
Feꢀ
Ptꢀ
Ptꢀ
Ptꢀ
Feꢀ
/
Pt
255.8(2)
226.5(3)
232.1(2)
200.1(6)
224.2(2)
Feꢀ
Feꢀ
Feꢀ
Feꢀ
/
C(1)
C(8)
C(9)
C(7)
200.6(6)
178.0(8)
175.3(7)
179.2(8)
123.0(8)
/
P(3)
P(2)
C(1)
/
/
/
/
/
/P(1)
C(1)ꢀN
/
Bond angles
C(1)ꢀFeꢀC(8)
P(1)ꢀC(22)ꢀP(2)
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
FeꢀC(1)ꢀ
P(2)ꢀPtꢀP(3)
PtꢀC(1)ꢀFe
Ptꢀ
Feꢀ
/
/
83.9(3)
114.6(3)
86.8(2)
C(1)ꢀ
FeꢀPtꢀ
FeꢀPtꢀ
P(1)ꢀFeꢀ
PtꢀC(1)ꢀ
C(1)ꢀFeꢀ
C(1)ꢀFeꢀ
C(9)ꢀFeꢀ
C(9)ꢀFeꢀ
C(7)ꢀFeꢀ
/
Nꢀ
P(3)
P(2)
/
C(2)
121.4(5)
152.12(5)
97.67(7)
95.49(8)
138.2(5)
88.0(3)
/
/
/
/
/
Feꢀ
Feꢀ
Feꢀ
Feꢀ
/
C(7)
C(8)
C(9)
C(1)
/
/
[11,14]. Like in the precursor [(OC)3Fe(m-CÄ
dppm)Pt(PPh3)] [FeꢀPt 257.9(4) pm], the metalꢀ
bond of 9 [FeꢀPt 255.8(2) pm] is much shorter than that
of 1a,c, 2 and 3c. As in the WꢀPt system, the m-CNR
/
O)(m-
/
/
94.6(2)
/
/
Pt
/
/metal
/
/
106.8(2)
145.68(18)
142.4(5)
110.08(8)
79.3(2)
/
/N
/
/
/
/
/
C(7)
C(9)
C(8)
C(7)
C(8)
/
/
/
N
/
/
107.4(3)
96.3(4)
/
/
/
/
ligand is strongly bent [121.4(5)8], the diethylphospho-
nate substituent being orientated towards the Fe(CO)3
/
/
/
/
95.0(4)
/
Feꢀ
Ptꢀ
/
C(1)
C(1)
50.25(17)
50.43(18)
/
/
167.6(3)
moiety. The bond length of the C(1)Ä
/
N double bond
/
/
[123.0(8) pm] is also very similar to that of 3c. However,

M. Knorr et al. / Journal of Organometallic Chemistry 684 (2003) 216ꢀ
/229
227
Fig. 6. View of the molecular structure of 9 with the numbering scheme.
3.5. Syntheses of m-aminocarbyne complexes
[(OC)4M{m-CN(H) R}(m-dppm)Pt(PPh3)] [BF4]
4. Conclusion
This empirical study has shown that the bonding
mode of the isocyanide ligand in complexes of the type
Like their dppa-bridged homologues, 2 and 3b are
converted instantaneously and quantitatively to the
[(OC)4M(CNR)(m-Ph2PXPPh2)Pt(PPh3)]
(Xꢁ/NH,
CH2; MꢁCr, Mo, W) depends exclusively on the
/
cationic m-aminocarbyne complexes [(OC)4M(m-CÄ
/
electronic propensities of the organic substituents R of
CNR ligand. Only in the case of very strongly with-
drawing substituents R, an asymmetric bridging bond-
ing mode is adopted. Even in the case of R groups,
which are considered moderately electron donating, a
terminal CNR bonding mode with conservation of the
m-CO bridge is preferred. This contrasts with the
behaviour of [(OC)3Fe(m-CO)(m-Ph2PXPPh2)Pt(PPh3)]
towards CNR, where even CNR ligands with good
N(H)R?)(m-dppm)Pt(PPh3)][BF4] (10 and 11) upon pro-
tonation with HBF4 on the basic isocyanide nitrogen
atom according Scheme 4. [15,33]
This electrophilic addition of H,ꢂ transforming m-
CNR into an excellently p-accepting aminocarbyne
ligand, enhances significantly the stability of the com-
plexes, allowing now the recording of 13C-NMR data.
The resonance of the m-carbyne carbon of 11 was
2
detected at d 327.8 (dd, JP,c
ꢁ11, 67 Hz) together
/
donor propensities such as Rꢁxylyl or benzyl adopt
/
with three sets of doublets for terminal carbonyl ligands
at d 207.8 (1 CO), 207.3 (1 CO, partially superimposed
with the first carbonyl resonance) and 205.5 (2 CO,
solely a symmetric m-CNR bonding mode.
2JP,c
ꢁ
/
9 Hz). A broad doublet at d 75.2 (4JP,c
ꢁ12 Hz)
/
is assigned to the NCH2 carbon, and a singlet at d 21.8
to the methyl carbon of the tosyl group. The following
trends in the 31P{1H}-NMR and 195Pt{1H}-NMR
spectra of 10 and 11 are apparent from Table 7: (i) in
comparison with the precursors 2 and 3b, the ddd
resonance of the 195Pt nucleus is shifted to ca. 300
5. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 206696 and 207729ꢀ207733
for compounds 2, 1a, 1c, 3c, 8 and 9, respectively.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
/
ppm to lower field (3b d ꢃ
/
2594; 11 d ꢃ2286); (ii) the
/
resonances of P1 and P2 in the 31P{1H}-NMR are shifted
3ꢂ4
to higher field; (iii) the
2ꢂ3
J
couplings increase markedly.
couplings are reduced,
P,P
whereas the
J
Cambridge CB2 1EZ, UK (Fax: ꢂ44-1223-336033; e-
/
Pt,P

228
M. Knorr et al. / Journal of Organometallic Chemistry 684 (2003) 216ꢀ229
/
Table 7
Selected 31P{1H}- and 195Pt{1H}-NMR data (d in ppm and J in Hz; for all Wꢀ
Pt compounds, the coupling constants given in this table correspond
/
to JAB, JAX and JBX
)
Complex
d(PM
)
d(PPt
)
d(PPh3)
2JP,P
,
2JP,P
,
3JP,P
;
1JPt,P
,
1JPt,P
,
2JPt,P
d(195Pt)
1a (Mꢁ
1b (Mꢁ
1c (Mꢁ
2 (Mꢁ
W) b
3a (Mꢁ
3b (Mꢁ
3c (Mꢁ
/
Cr)
55.9 dd
34.3 dd
12.2 dd
1.6 dd
10.1 dd
15.1 dd
14.0 dd
2.9 dd
45.1 dd
149, 61, 35; 3309, 4724
153, 63, 27; 3472, 4415, 65
160, 54, 17
ꢃ
/
2431.5 dd
2514.5 ddd a
2484 ddd
/Mo)
45.8 dd
48.3 dd
48.4 tq c
42.8 dd
43.6 dd
45.5 t
ꢃ/
4452, 3352, 41
129, 30, 31
/W)
ꢃ/
4768, 2808, 15
121, 42, 36; 4725, 2892
132, 41, 37; 4590, 3018
132, 36, 36
/
/Cr)
46.9 dd
26.0 dd
0.97 dd
0.8 dd
2.8 dd
ꢃ
/
2530 dd
4573, 2966, 29
124, 33, 29
4526, 2849
/Mo)
6.9 dd
/W)
5.33 dd
3.8 dd
159, 50, 12
4456, 3340, 40
159, 54, 17
ꢃ
/
2594 ddd
4 (Mꢁ
5 (Mꢁ
6 (Mꢁ
/
W) d
W)
44.2 dd
48.0 dd
48.8 dd
45.0 dd
4486, 3342, 40
149, 31, 33
4230, 2876
/
11.7 dd
12.6 dd
1.9 dd
13.6 dd
14.5 dd
6.3 dd
ꢃ
/
2490 ddd
2507 ddd
2616 dd f
/W)
96;
ꢃ/
1JW,P
90;
ꢁ/239
7a (Mꢁ
8a (Mꢁ
8b (Mꢁ
9 (Mꢁ
10 (Mꢁ
11 (Mꢁ
/
W) e
W)
ꢃ/
/
11.4 d, ꢃ
12.0 d, ꢃ
70.7 dd
6.5 dd
17.1 dd
/
25.2 d
/W)
/24.4 d
/
Fe) g
29.5 dd
39.6 dd
39.49 dd
40.1 d
149, 26, 6;
4199, 2538, 60
72, 25, 1;
ꢃ
/
2598 ddd
/W)
ꢃ/
ꢃ
/
7.8 dd
4159, 2574, 73
80, 22;
4346, 2549, 66
/Mo)
3.4 dd
ꢃ
/
2286 ddd
a
b
c
d
e
f
In C6D6 ꢀ
19F-NMR: dꢁ
5JF,P
4 Hz.
d([PPh3CH2NC]ꢂ)ꢁ
d(PO(OEt)2)ꢁ21.2, s.
not resolved.
/
CH2Cl2.
/
ꢃ
/
56, s.
ꢁ/
4
/
15.1, s, JPt,P
ꢁ/22 Hz.
/
2ꢂ3
Pt,P
J
g
d(PO(OEt)2)ꢁ23.6, s.
/
[3] J.A. Howell, J.Y. Saillard, A.L. Beuze G. Jaouen, J. Chem. Soc.
Dalton Trans. (1982) 2533.
[4] D. Lentz, Angew. Chem. Int. Ed. Engl. 33 (1994) 1315.
mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
[5] D. Lentz, M. Rottger, J. Organomet. Chem. 592 (1999) 41.
¨
[6] D. Lentz, S. Willemsen, J. Organomet. Chem. 612 (2000) 96.
[7] J. Buschmann, D. Lentz, P. Luger, M. Rottger, G. Perpetuo, D.
¨
Acknowledgements
Scharn, S. Willemsen, Z. Anorg. Allg. Chem. 626 (2000) 2107.
[8] M. Knorr, P. Braunstein, A. Tiripicchio, F. Ugozzoli, J.
Organomet. Chem. 526 (1996) 105.
We are grateful to the Deutschen Forschungsge-
meinschaft and the French Ministe`re de la Recherche
et Technologie for financial support.
[9] M. Knorr C. Strohmann, Eur. J. Inorg. Chem. (1998) 495.
[10] M. Knorr, C. Strohmann, P. Braunstein, Organometallics 15
(1996) 5653.
[11] M. Knorr C. Strohmann, Eur. J. Inorg. Chem. (2000) 241.
[12] P. Braunstein, M. Knorr, G. Reinhard, U. Schubert, T. Stahr-
¨
feldt, Chem. Eur. J. 6 (2000) 4265.
[13] P. Braunstein, J. Durand, M. Knorr C. Strohmann, J. Chem. Soc.
Chem. Commun. (2001) 211.
References
[14] M. Knorr, I. Jourdain, G. Crini, K. Frank, H. Sachdev, C.
Strohmann, Eur. J. Inorg. Chem. (2002) 2419.
[15] M. Knorr, C. Strohmann, Organometallics 18 (1999) 248.
[1] J.Y. Saillard, A.L. Beuze, G. Simmoneaux, P.L. Maux, G.
Jaouen, J. Mol. Struct. 86 (1981) 149.
[2] B.E. Bursten, R.F. Fenske, Inorg. Chem. 16 (1977) 963.

M. Knorr et al. / Journal of Organometallic Chemistry 684 (2003) 216ꢀ
/229
229
Table 8
Crystallographic data
1a
1c
2
3c
8a
9
Formula
FW
T (K)
C65.50H55.50CrO5P3Pt C49H39Cl2O5P3PtW C49H37F3NO4P3PtW C57.50H49Cl3NO6P3PtSW C38H30Cl3NO4P2W C53H51Cl2FeNO6P4Pt
1243.67
293(2)
1262.60
173(2)
1250.55
173(2)
1232.65
153(2)
1460.24
293(2)
916.77
173(2)
Crystal size 0.20ꢄ
/0.20ꢄ/0.10
0.20ꢄ/0.20ꢄ/0.10
0.14ꢄ
/
0.09ꢄ
/
0.04
0.20ꢄ/0.10ꢄ/0.10
0.20ꢄ
/
0.20ꢄ
/
0.10 0.20ꢄ
/
0.20ꢄ0.10
/
(mm3)
Crystal sys- Triclinic
tem
Triclinic
Triclinic
Monoclinic
Monoclinic
Triclinic
¯
Space group P1
¯
P1
¯
P1
¯
P1
P21/n
P21/c
Unit cell di-
mensions
˚
a (A)
12.516(3)
14.938(2)
17.160(4)
69.81(2)
71.97(3)
79.02(3)
2851.0(11)
2
11.146(7)
11.879(9)
18.45(2)
79.33(12)
80.21(10)
74.18(8)
2291(3)
2
11.4307(14)
12.0368(15)
19.095(2)
103.322(3)
97.823(3)
110.848(3)
2319.4(5)
2
14.961(3)
21.295(4)
18.387(4)
90
9.0039(17)
39.092(15)
10.708(2)
90
11.779(8)
13.322(9)
18.451(11)
86.88(5)
75.49(5)
68.41(5)
2604(3)
2
˚
b(A)
˚
c (A)
a (8)
b (8)
g (8)
104.87(3)
90
99.81(2)
90
3
˚
V (A )
5662(2)
4
1.713
3713.8(17)
4
1.640
Z
r calc
(g.cmꢃ3
m (mmꢃ1
F(000)
1.471
1.813
1.765
1.586
)
)
2.775
1271
5.825
1208
5.650
1188
4.811
2852
3.453
1808
3.237
1244
u Range (8) 2.15ꢀ
/
27.00
155h 5
195k 519, ꢃ
l 521
30617
2.26ꢀ
125
145k 5
225l 522
15636
8433
/
26.00
h 5
14, ꢃ
1.89ꢀ
145
155k 5
l 524
51804
10693
/
27.00
h 5
15, ꢃ
1.57ꢀ
165
22, 05
/
22.50
h 5
l 5
2.19ꢀ
105
465k 5
125l 511
22326
6369
/
25.00
h 5
46, ꢃ
1.65ꢀ
125
155k 5
/
23.99
h 5
15, 05
Index
ranges
ꢃ/
/
/
15, ꢃ
/
ꢃ/
/
/
13, ꢃ
/
ꢃ/
/
/
14, ꢃ
/
ꢃ/
/
/
15, 05
/
k 5
/
ꢃ/
/
/
9, ꢃ
/
ꢃ/
/
/
13, ꢃ
/
/
/
/215
/
/
/
/
/
/
/
245
/
/
/
19
/
/
/
/
/
/
l 5
/
/
/
/
/
/
/
21
Collected
reflections
7391
7391
8176
Independent 11590
reflections
8176
Data/re-
straints/
parameters
11590/0/687
8433/0/550
10693/0/559
7391/0/655
6369/0/424
8176/0/615
Largest dif- 1.155 and ꢃ
/
1.729
2.653 and ꢃ
/
5.337 1.846 and ꢃ
/
0.990
1.195 and ꢃ
/
0.664
1.085 and ꢃ
/
1.651 1.414 and ꢃ1.665
/
ference peak
and hole (e
ꢃ3
˚
A
)
Final R in- R1ꢁ
/
0.0326, wR2ꢁ
/
R1ꢁ
wR2ꢁ
/
0.0516,
R1ꢁ
0.0496
/
0.0255, wR2ꢁ
/
R1ꢁ
0.0748
/
0.0342, wR2ꢁ
/
R1ꢁ
wR2ꢁ
/
0.0455,
0.1110
R1ꢁ
0.099
/
0.0404, wR2ꢁ
/
dices [I ꢀ 0.0792
/
/0.1300
/
2s(I)]
R indices
(all data)
R1ꢁ
0.0814
GOF on F2 1.025
/
0.0392, wR2ꢁ
/
R1ꢁ
wR2ꢁ
1.050
/
0.0606,
R1ꢁ
0.0585
1.026
/
0.0598, wR2ꢁ
/
R1ꢁ
0.0839
1.097
/
0.0482, wR2ꢁ
/
R1ꢁ
wR2ꢁ
1.005
/
0.0657,
R1ꢁ
0.1070
1.091
/
0.0499, wR2ꢁ
/
/0.1370
/0.1182
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