Synthesis, molecular structure, and reactivity of rhodium(I) complexes with diazoalkanes and related substrates as ligands

Article abstract of DOI:10.1021/om0302037

Synthesis, molecular structure and reactivity of rhodium (I) complexes were discussed. X-ray crystal structure analysis was used. Results showed the chelating bonding mode of the diazo ligand. An isomer was also found that which is derived from keto ester

Full text of DOI:10.1021/om0302037

3566
Organometallics 2003, 22, 3566-3576
Syn th esis, Molecu la r Str u ctu r e, a n d Rea ctivity of
Rh od iu m (I) Com p lexes w ith Dia zoa lk a n es a n d Rela ted
Su bstr a tes a s Liga n d s
Helmut Werner,*,† Norbert Mahr,† J ustin Wolf,† Arno Fries,†
Matthias Laubender,† Elke Bleuel,† Raquel Garde,†,‡ and Pascual Lahuerta‡
Institut fu¨r Anorganische Chemie der Universita¨t Wu¨rzburg, Am Hubland,
D-97074 Wu¨rzburg, Germany, and Departament de Quı´mica Inorga`nica,
Universitat de Vale`ncia, Doctor Moliner 50, E-46100 Burjassot, Vale`ncia, Spain
Received March 17, 2003
A series of (diazoalkane)rhodium(I) compounds of the general composition trans-[RhCl-
(N2CRR′)(PiPr3)2] with R ) R′ ) Ph, p-C6H4Me, p-C6H4Cl and R ) Ph, R′ ) p-C6H4Me, o-C6H4-
Me, CH3, CH2Ph, CF3 has been prepared from the dimer [RhCl(PiPr3)2]2 (1) and the
diazoalkane. This preparative route has also been extended to complexes in which the N2C
unit(s) of 1,4-C6H4{C(Ph)N2}2, 9-diazofluorene, 9,10-anthraquinone-9-diazide, and 3-methyl-
1,4-naphthoquinone-1-diazide is (are) linked to a 14-electron [RhCl(PiPr3)2] fragment. While
C(CO2Et)2N2 behaves as expected and affords upon treatment with 1 the complex trans-
[RhCl{N2C(CO2Et)2}(PiPr3)2), CH(CO2Et)N2 reacts with the same starting material to give
the dinitrogen derivative trans-[RhCl(N2)(PiPr3)2] (12). The reactions of trans-[RhCl(C2H4)-
(PiPr3)2] (2) with both N2CC4Cl4 and N2CC4Ph4 afford trans-[RhCl(N2CC4X4)(PiPr3)2] (X )
Cl, Ph), and the same type of ligand exchange takes place by treatment of trans-[RhCl-
(C2H4)(SbiPr3)2] with N2CC4Cl4. The reactions of trans-[RhCl(N2CRR′)(PiPr3)2] (3-7, where
R and R′ are aryl) with excess ethene give, instead of a disubstituted cyclopropane, exclusively
the trisubstituted olefin CH3CHdCRR′. The reaction of 1 with PhC(R)NNH2 (R ) Ph, Me)
proceeds mainly by orthometalation to yield the six-coordinate rhodium(III) complexes [Rh-
(H)Cl{κ2-C,N-C6H4C(NNH2)R}(PiPr3)2]; of these, that with R ) Ph reacts with Al2O3 to give
trans-[RhCl(N2CPh2)(PiPr3)2] and 12. The alkynylrhodium(I) derivatives trans-[Rh(CtCX)-
(C2H4)(PiPr3)2] (X ) H, tBu) behave similarly to 2 and afford upon treatment with Ph2CN2
and C12H8CN2 the corresponding diazoalkane compounds trans-[Rh(CtCX)(N2CRR′)(PiPr3)2]
by ligand exchange. The reaction of 2 with the diazo ketones RC(O)C(Ph)N2 (R ) Ph, Me)
leads to complexes of the general composition [RhCl{N2C(Ph)C(O)Ph}(PiPr3)2], in which the
diazo ketone is probably coordinated in a chelating fashion to the metal center. The keto
ester derivative (CH3)2CHCH2CH2C(O)C(CO2Me)N2 reacts with 2 to give a mixture of two
isomers, one of which could be separated by fractional crystallization. The supposed chelating
bonding mode of the diazo ligand in this compound via the terminal nitrogen and the keto
oxygen could be confirmed by an X-ray crystal structure analysis.
In tr od u ction
[RhCl(PiPr3)2]2, which was previously employed as the
starting material for the preparation of trans-[RhCl-
(dCdCRR′)(PiPr3)2] and trans-[RhCl{dC(dC)nRR′)-
(PiPr3)2], with various diazoalkanes at ambient tem-
peratures. After we failed to obtain the rhodium carbenes
trans-[RhCl(dCRR′)(PiPr3)2] by this route,4 we found
that it is more appropriate to prepare in the initial step
the corresponding bis(stibine) derivatives trans-[RhCl-
(dCRR′)(SbiPr3)2] and subsequently replace the two
stibines for two phosphine ligands.5 Both the bis(stibine)
and the bis(phosphine) complexes could be converted to
the η5-cyclopentadienyl compounds [(η5-C5H5)Rh(dCRR′)-
(EiPr3)] (E ) P, Sb),6 which, similarly to the square-
planar counterparts, have a rich chemistry indeed.
In the context of our studies on rhodium vinylidenes
trans-[RhCl(dCdCRR′)(PiPr3)2]1 and their homologues
trans-[RhCl{dC(dC)nRR′)(PiPr3)2] (n ) 2,2 43), we also
attempted to prepare the parent compounds of this
series, having the general composition trans-[RhCl-
(dCRR′)(PiPr3)2]. Since the obvious choice to generate
the required carbene ligand :CRR′ was to use diazo-
alkanes RR′CN2 as precursors, we treated the dimer
† Universita¨t Wu¨rzburg.
‡ Universitat de Vale`ncia.
(1) (a) Garcia Alonso, F. J .; Ho¨hn, A.; Wolf, J .; Otto, H.; Werner, H.
Angew. Chem. 1985, 97, 401-402; Angew. Chem., Int. Ed. Engl. 1985,
24, 406-408. (b) Werner, H.; Garcia Alonso, F. J .; Otto, H.; Wolf, J . Z.
Naturforsch. 1988, 43b, 722-726. (c) Werner, H.; Brekau, U. Z.
Naturforsch. 1989, 44b, 1438-1446.
(2) (a) Werner, H.; Rappert, T. Chem. Ber. 1993, 126, 669-678. (b)
Werner, H.; Rappert, T.; Wiedemann, R.; Wolf, J .; Mahr, N. Organo-
metallics 1994, 13, 2721-2727.
(3) Kovacik, I.; Laubender, M.; Werner, H. Organometallics 1997,
16, 5607-5609.
(4) Wolf, J .; Brandt, L.; Fries, A.; Werner, H. Angew. Chem. 1990,
102, 584-586; Angew. Chem., Int. Ed. Engl. 1990, 29, 510-512.
(5) (a) Schwab, P.; Mahr, N.; Wolf, J .; Werner, H. Angew. Chem.
1993, 105, 1498-1500; Angew. Chem., Int. Ed. Engl. 1993, 32, 1480-
1482. (b) Werner, H.; Schwab, P.; Bleuel, E.; Mahr, N.; Steinert, P.;
Wolf, J . Chem. Eur. J . 1997, 3, 1375-1384.
10.1021/om0302037 CCC: $25.00 © 2003 American Chemical Society
Publication on Web 07/22/2003

Rh(I) Complexes with Diazoalkanes as Ligands
Organometallics, Vol. 22, No. 17, 2003 3567
Sch em e 1a
Sch em e 2a
a
L ) PiPr3.
elemental analysis and spectroscopic techniques. With
respect to the bonding mode, the position of the ν(N2C)
stretching vibration at ca. 1935-1940 cm-1 in the IR
spectra suggests an end-on coordination of the RR′CN2
ligand.10 The 1H NMR spectra of 3-10 display one
doublet of virtual triplets for the PCHCH3 protons,
indicating that, in contrast to the starting material 1,
the two phosphine units are in a trans disposition.11,12
In the 13C NMR spectra, the resonance for the diazo-
alkane carbon atom RR′CN2 appears at δ 72.2-78.7 (3-
7, 9) or 65.9 (10) as a broad singlet, the broadening
probably being due to the quadrupole moment of the
nitrogen atoms. Regarding the stability of the products,
it should be mentioned that complex 8, formed from
1-phenyldiazoethane, in solution slowly decomposes to
generate trans-[RhCl(N2)(PiPr3)2] (12).8,13
The dinitrogen compound 12 is also obtained from 1
and CH(CO2Et)N2 (see Scheme 2). In contrast, treat-
ment of the starting material 1 with the diester C(CO2-
Et)2N2 gives, under the same conditions as used for the
preparation of 3-10, the expected diazoalkane complex
11 in 80% isolated yield. The IR spectrum of the air-
stable product shows the ν(CdO) stretching mode at
1730 cm-1, thus almost the same position as for the free
ligand. Therefore, a possible interaction of one of the
CdO ester groups with the metal can be excluded. In
this context we note that the reaction of 1 with PhC-
(O)CHN2 leads to the formation of the unusual com-
pound [RhCl(PiPr3){iPr3PCHC(O)Ph}], in which the
functionalized ylide is coordinated like an η3-allyl ligand
via the ylidic carbon, the acyl carbon, and the oxygen
to the rhodium center.14
a
L ) PiPr3.
The present paper describes the synthesis and mo-
lecular structure of the diazoalkane complexes trans-
[RhCl(N2CRR′)(PiPr3)2], originally considered as useful
precursors for the generation of four-coordinate rhodium
carbenes, and the reactions of these compounds toward
ethene. Moreover, we report the preparation of the
series of alkynylrhodium(I) derivatives trans-[Rh(CtCX)-
(N2CRR′)(PiPr3)2] and the isolation and structural char-
acterization of an unusual rhodium complex with a
coordinated diazo keto ester that behaves as a chelating
ligand. Some preliminary results of this work have
already been communicated.4
Resu lts a n d Discu ssion
P r ep a r a tion of Rh od iu m (I) Com p lexes w ith Co-
or d in a t ed P h 2CN2 a n d Der iva t ives Th er eof. The
peculiar dimer 17 reacts with diazomethane in diethyl
ether to give, instead of trans-[RhCl(dCH2)(PiPr3)2] or
trans-[RhCl(N2CH2)(PiPr3)2], exclusively the correspond-
ing (ethene)rhodium compound 2 (Scheme 1), being also
accessible from 1 and C2H4.8 Since the reaction of 1 with
CH2N2 is quite fast even at low temperature, we failed
to find out whether the diazomethane and/or the car-
bene complex is formed as an intermediate.
Similarly to CH2N2, diphenyldiazomethane and de-
rivatives thereof are also highly reactive toward com-
pound 1 and afford either in diethyl ether or in toluene
the diazoalkane complexes 3-10 in good to excellent
yields. The addition of the RR′CN2 ligand to the
postulated 14-electron species [RhCl(PiPr3)2], formed by
dissociation of 1,9 is accompanied by a characteristic
change of color from violet to green. The isolated
products, with the exception of 10, are air-sensitive but
can be stored at room temperature under argon for days
without decomposition. They were all characterized by
The results covering the reactions of dimer 1 with 1,4-
bis(R-diazophenyl)benzene, 9-diazofluorene, and the
anthraquinone and naphthoquinone derivatives N2-
CC13H8O and N2CC10H8O are summarized in Scheme
3. In diethyl ether or toluene as solvent, the substrates
react nearly spontaneously to give the dinuclear (13)
or mononuclear (14-16) complexes as green or red-
brown air-stable solids in 79-89% yield. One typical
(10) Inter alia: (a) Albini, A.; Kisch, H. Top. Curr. Chem. 1976, 65,
105-145. (b) Herrmann, W. A. Angew. Chem. 1978, 90, 855-868;
Angew. Chem., Int. Ed. Engl. 1978, 17, 800-813. (c) Hidai, M.; Mizobe,
Y.; Sato, M.; Kodama, T.; Uchida, Y. J . Am. Chem. Soc. 1978, 100,
5740-5748. (d) Ibers, J . A.; Gaffney, T. R.; Schramm, K. D. Coord.
Chem. Rev. 1980, 21, 141-149. (e) Sutton, D. Chem. Rev. 1993, 93,
995-1022.
(6) Werner, H.; Schwab, P.; Bleuel, E.; Mahr, N.; Windmu¨ller, B.;
Wolf, J . Chem. Eur. J . 2000, 6, 4461-4470.
(7) (a) Preparation: Werner, H.; Wolf, J .; Ho¨hn, A. J . Organomet.
Chem. 1985, 287, 395-407. (b) Molecular structure: Binger, P.; Haas,
J .; Glaser, G.; Goddard, R.; Kru¨ger, C. Chem. Ber. 1994, 127, 1927-
1929.
(8) (a) Busetto, C.; D’Alfonso, A.; Maspero, F.; Perego, G.; Zazetta,
A. J . Chem. Soc., Dalton Trans. 1977, 1828-1834. (b) Werner, H.;
Feser, R. J . Organomet. Chem. 1982, 232, 351-370.
(9) Schneider, D.; Werner, H. Angew. Chem. 1991, 103, 710-712;
Angew. Chem., Int. Ed. Engl. 1991, 30, 700-702.
(11) (a) Windmu¨ller, B.; Wolf, J .; Werner, H. J . Organomet. Chem.
1995, 502, 147-161. (b) Windmu¨ller, B.; Nu¨rnberg, O.; Wolf, J .;
Werner, H. Eur. J . Inorg. Chem. 1999, 613-619.
(12) Harris, R. K. Can. J . Chem. 1964, 42, 2275-2281.
(13) Thorn, D. L.; Tulip, T. H.; Ibers, J . A. J . Chem. Soc., Dalton
Trans. 1979, 2022-2025.
(14) Werner, H.; Mahr, N.; Frenking, G.; J onas, V. Organometallics
1995, 14, 619-625.

3568 Organometallics, Vol. 22, No. 17, 2003
Werner et al.
Sch em e 3a
F igu r e 1. Molecular diagram of compound 15. Selected
bond distances (Å) and angles (deg): Rh-P(1) ) 2.3539-
(15), Rh-P(2) ) 2.3512(15), Rh-Cl ) 2.3093(16), Rh-N(1)
) 1.836(5), N(1)-N(2) ) 1.150(6), N(2)-C(1) ) 1.326(8);
P(1)-Rh-P(2) ) 176.91(5), Cl-Rh-N(1) ) 175.84(16),
P(1)-Rh-Cl ) 89.72(5), P(1)-Rh-N(1) ) 90.62(15), P(2)-
Rh-Cl ) 88.84(6), P(2)-Rh-N(1) ) 91.01(15), Rh-N(1)-
N(2) ) 173.7(5), N(1)-N(2)-C(1) ) 172.3(8).
a
L ) PiPr3.
spectroscopic feature of 15 and 16 is the position of the
ν(N2C) vibration at 2083 cm-1 (for 15) and 2088 cm-1
(for 16), which appears at significantly higher wave-
numbers than for 3-11, 13, and 14. The 13C NMR
spectra of 15 and 16 display a sharp singlet at δ 178.9
(for 15) and 178.8 (for 16), being characteristic for a
quinone-type CdO carbon atom. Attempts to link only
one N2C unit of 1,4-bis(R-diazophenyl)benzene to the 14-
electron [RhCl(PiPr3)2] fragment remained unsuccessful.
To confirm the proposed bonding mode of N2CC13H8O,
an X-ray crystal structure analysis of compound 15 was
carried out. The ORTEP plot (Figure 1) reveals that the
coordination sphere around the rhodium center is
slightly distorted square planar. The two phosphine
ligands are trans to each other, forming a P(1)-Rh-
P(2) axis with a bond angle of 176.91(5)°. The diazo-
alkane unit is only coordinated via the terminal nitrogen
atom with a Rh-N(1) distance of 1.836(5) Å, which is
somewhat shorter than in the cation trans-[Rh(acetone)-
(N2CPh2)(PiPr3)2]+ (1.869(3) Å)15 and in the dinitrogen
complex 12 (1.885(4) Å).13 In contrast to the Rh(N2CC4-
Cl4) derivative 20 (see below), the Rh-N(1)-N(2) axis
is not significantly bent, which could be a consequence
of the steric requirements caused by the bulky triiso-
propylphosphine ligands and the N2CC13H8O unit. The
plane [P(1),P(2),Cl,N(1)] is nearly perpendicular to the
plane formed by the carbon atoms C(1), C(2), C(7), C(8),
C(9), and C(14), the dihedral angle being 79.6°. The bond
length N(1)-N(2) at 1.150(6) Å is almost identical with
that in the cation [Rh(acetone)(N2CPh2)(PiPr3)2]+
(1.157(4) Å) and lies between those of an NdN double
bond and an NtN triple bond.16 Regarding the bonding
mode of the N2CC13H8O moiety, we note that in the
Sch em e 4a
a
L ) PiPr3, L′ ) SbiPr3.
related nickel complex [Ni(N2CC12H8)(CNtBu)2] the
9-diazofluorene is coordinated side-on and thus both
nitrogen atoms are linked to the metal center.17
R h od iu m (I) Com p lexes w it h Coor d in a t ed
N2CC4X4 Un its. After it had been shown that chloro-
metal compounds such as [RhCl(η4-C8H12)]2 react with
the diazocyclopentadiene derivative N2CC4Cl4 to afford
half-sandwich-type complexes with C5Cl5 as a η5-bonded
ligand,18 we were prompted to study also the reactivity
of 2 (being more easily to handle than 1) toward N2-
CC4Cl4 and the tetraphenyl counterpart N2CC4Ph4.
However, instead of [(η5-C5R5)Rh(PiPr3)2] or [(η5-C5R5)-
Rh(C2H4)(PiPr3)] (R ) Cl, Ph) we isolated the (diazo-
cyclopentadiene)rhodium(I) compounds 17 and 18 in
almost quantitative yield (Scheme 4). The deep green
(17) or brown-yellow (18) solids are air-stable and
readily soluble in solvents such as benzene, chloroform,
and dichloromethane. Even if they are stored in solution
at room temperature for several days, no conversion to
(15) Werner, H.; Schneider, M. E.; Bosch, M.; Wolf, J .; Teuben, J .
H.; Meetsma, A.; Troyanov, S. I. Chem. Eur. J . 2000, 6, 3052-3059.
(16) Wells, A. F. Structural Inorganic Chemistry, 5th ed.; Clarendon
Press: Oxford, U.K., 1984; Chapter 18.
(17) Nakamura, A.; Yoshida, T.; Cowie, M.; Otsuka, S.; Ibers, J . A.
J . Am. Chem. Soc. 1977, 99, 2108-2117.
(18) Reimer, K. J .; Shaver, A. Inorg. Chem. 1975, 14, 2707-2716.

Rh(I) Complexes with Diazoalkanes as Ligands
Organometallics, Vol. 22, No. 17, 2003 3569
Sch em e 5a
a
L ) PiPr3.
π-acceptor ligand. It should be noted that in the complex
[Ru(CO)2(PPh3)2(N2CC4Cl4)] the diazocyclopentadiene
unit is not end-on but side-on bonded via both nitrogen
atoms to the ruthenium center.21
Rea ction s of th e Dia zoa lk a n e Com p lexes w ith
Eth en e. Since it is known that dinuclear rhodium(II)
compounds such as [Rh2(O2CMe)4] and derivatives
thereof catalyze the reactions of ethene and diaryldi-
azomethanes to give substituted cyclopropanes,22 we
also attempted to use the rhodium(I) complexes 3-7 for
cyclopropanation reactions. By treating 3-7 in benzene
at room temperature, only a very slow reaction occurs.
After raising the temperature to 40 °C, an equilibrium
between the diazoalkane complex and the corresponding
ethene derivative 2 is reached, which under an ethene
atmosphere lies mainly on the side of 2. Most surpris-
ingly, the product generated from the coordinated
diazoalkane and ethene is not the expected 1,1-diaryl-
cyclopropane but CH3CHdCRR′ (Scheme 5). This olefin
is formally built up by the linking of the :CRR′ fragment
of the diazoalkane, with :CHCH3 being an isomer of
ethene. Within the accuracy of NMR measurements, the
yield of CH3CHdCRR′ is quantitative. To explain the
mechanism of the unusual C-C coupling reaction, we
assume that in the initial stage both C2H4 and RR′CN2
are coordinated to rhodium and that, after elimination
of N2, a four-membered RhC3 metallacycle is formed.
The next step could be an H-shift from the â-CH2 unit
of the metallacyclobutane ring to afford a η3-allyl-
(hydrido)rhodium intermediate, which by reductive
coupling of the hydrido ligand with the CH2 carbon atom
of the η3-CH2CHCRR′ moiety generates the olefin CH3-
CHdCRR′. Compound 14 behaves similarly to 3-7 and
upon treatment with ethene gives 2 and the fulvene
derivative CH3CHdCC12H8.
F igu r e 2. Molecular diagram of compound 20. Selected
bond distances (Å) and angles (deg): Rh-Sb(1) ) 2.5912(8),
Rh-Sb(2) ) 2.6022(8), Rh-Cl ) 2.291(2), Rh-N(1) )
1.788(6), N(1)-N(2) ) 1.144(8), N(2)-C(1) ) 1.37(1);
Sb(1)-Rh-Sb(2) ) 171.46(3), Cl-Rh-N(1) ) 178.3(2), Rh-
N(1)-N(2) ) 170.1(8), N(1)-N(2)-C(1) ) 154(1).
a [Rh(η5-C5R5)] derivative, to a carbenerhodium(I) com-
plex, or to 12 occurs. The chemical shift of the N2C
carbon resonance in the 13C NMR spectra of 17 and 18
differs only slightly from that of 3 or 14 and 15, and
thus we assume that the diazocyclopentadiene units are
bonded end-on to the metal center.
Taking into consideration that, in contrast to 1 or 2,
the bis(stibine) compound 19 reacts with Ph2CN2 and
other diazoalkanes such as (p-Tol)2CN2, (p-Tol)C(Ph)-
N2, and CF3C(Ph)N2 to give the corresponding carbene
complexes trans-[RhCl(dCRR′)(SbiPr3)2] by elimination
of N2,5 we also investigated the reactivity of 19 toward
N2CC4Cl4. However, instead of obtaining trans-[RhCl-
(dCC4Cl4)(SbiPr3)2] we isolated the corresponding di-
azocyclopentadiene complex 20 as an olive green solid
in excellent yield. The molecular structure of 20 has
been determined crystallographically and is shown in
Figure 2. Similarly to 15, the coordination geometry is
distorted square-planar with bond angles for the N(1)-
Rh-Cl and Sb(1)-Rh-Sb(2) axes of, respectively,
178.3(2) and 171.46(3)°. The N2CC4Cl4 unit possesses
the “singly bent” configuration, as has also been found
for the iridium compounds trans-[IrCl(N2CC4Cl4)-
(PPh3)2]19 and trans-[IrCl(N2CC4Cl4)(SbiPr3)2].20 The
nitrogen, carbon, and chlorine atoms of the coordinated
diazocyclopentadiene derivative lie in one plane which
is nearly perpendicular to the plane containing Rh, Cl,
Sb(1), and Sb(2). The dihedral angle between the two
planes is 85.5(2)°. In analogy to 15, the distance N(1)-
N(2) of 1.144(8) Å is halfway between those of a NdN
double bond and a NtN triple bond, being in agreement
with the assumption that N2CC4Cl4 is a moderate
Rea ction s of Dim er 1 w ith P h en ylh yd r a zon es.
To find out whether diazoalkanerhodium(I) complexes
such as 3 and 8 can be obtained without using RR′CN2
as the precursors, the reactivity of 1 toward phenyl
hydrazones has been investigated. There is ample
evidence for the ability of phosphinerhodium(I) com-
pounds of the general compositions [RhCl(PR3)2]2 and
(21) Schramm, K. D.; Ibers, J . A. Inorg. Chem. 1980, 19, 2441-2448.
(22) Leading references: (a) Doyle, M. P. Chem. Rev. 1986, 86, 919-
939. (b) Padwa, A.; Krumpe, K. E. Tetrahedron 1992, 48, 5385-5453.
(c) Doyle, M. P.; McKervey, M. A. Chem. Commun. 1997, 983-989.
(d) Doyle, M. P. Pure Appl. Chem. 1998, 70, 1123-1128. (e) Barberis,
M.; Pe´rez-Prieto, J .; Herbst, K.; Lahuerta, P. Organometallics 2002,
21, 1667-1673.
(19) (a) Schramm, K. D.; Ibers, J . A. Inorg. Chem. 1980, 19, 1231-
1236. (b) Schramm, K. D.; Ibers, J . A. Inorg. Chem. 1980, 19, 2435-
2440.
(20) Ortmann, D. A.; Weberndo¨rfer, B.; Ilg, K.; Laubender, M.;
Werner, H. Organometallics 2002, 21, 2369-2381.

3570 Organometallics, Vol. 22, No. 17, 2003
Werner et al.
Sch em e 6a
Sch em e 7a
a
L ) PiPr3.
[RhCl(PR3)3] to react with hydrocarbons or other organic
molecules by abstraction of hydrogen and formation of
hydridorhodium complexes.23
a
L ) PiPr3.
attempted to generate 3 from 21 by using a chromato-
graphic column filled with deactivated Al2O3, we ob-
tained a mixture of 3 and the dinitrogen compound 12
in small quantities. Further attempts to form 3 by
treatment of 21 with [RhCl(PPh3)3] or 1 remained
unsuccessful.
Treatment of a solution of the starting material 1 with
diphenyl hydrazone in toluene leads to a rapid change
of color from violet to red-brown and gives, after
extraction with and recrystallization from pentane, the
ortho-metalated rhodium(II) compound 21 in 70% iso-
lated yield. In the mother liquor, besides 21 the di-
azoalkane complex 3 could be detected in small quanti-
ties. Typical spectroscopic features of 21 are the hydride
Alk yn ylr h od iu m (I) Com p lexes w it h Dia zoa l-
k a n e Liga n d s. After we found that in iridium com-
plexes trans-[IrX(N2CRR′)(PiPr3)2] the bond between
iridium and the diazoalkane ligand could be stabilized
if instead of chloride an alkyl or alkynyl group is linked
to the metal center,25 we also studied the reactivity of
alkynylrhodium compounds trans-[Rh(CtCX)(C2H4)-
(PiPr3)2] toward diazoalkanes. The hope, however, that
with these starting materials it could be possible to even
isolate a rhodium(I) complex with coordinated CH2N2
or PhCHN2, was not fulfilled. While both 23 and 26 (see
Scheme 7) react with Ph2CN2 and C12H8CN2 in pentane
to give the expected diazoalkane complexes 24, 25, 27,
and 28 in 79-95% yield, the reactions of 23 and 26 with
CH2N2 or PhCHN2 give mixtures of products which
could not be separated by common techniques. If the
reaction of 26 with PhCHN2 in toluene-d8 was moni-
tored at -40 °C in an NMR tube, the 1H NMR spectrum
displayed a signal at δ 4.14, which could be tentatively
assigned to the PhCH proton of the required compound
trans-[Rh(CtCtBu)(N2CHPh)(PiPr3)2]. After the tem-
perature was raised to 0 °C, this signal completely
disappeared. At this stage, the IR spectrum of the
solution showed an absorption at 2120 cm-1, indicating
that possibly the dinitrogen complex trans-[Rh(CtCtBu)-
(N2)(PiPr3)2] had been generated. In contrast to 12, this
molecule seems to be very labile, and thus all attempts
to isolate it failed.
1
signal at δ -14.22 in the H NMR spectrum, which is
1
split into a doublet of triplets due to 1H-103Rh and H-
31P couplings, the low-field resonance at δ 167.2 (also a
doublet of triplets) in the 13C NMR spectrum, assigned
to the metal-bonded carbon atom of the six-membered
ring, and the ν(NH) stretches at 3360 and 3248 cm-1 in
the IR spectrum, indicating that the NNH2 unit is still
intact. The fact that the two phosphine ligands of 21
are stereochemically equivalent is confirmed by the
appearance of only one signal (doublet) in the 31P NMR
1
spectrum. In the corresponding H-decoupled 31P NMR
spectrum this doublet becomes a doublet of doublets due
to additional coupling of the 31P nuclei with the hydride.
The reaction of 1 with CH3C(Ph)dNNH2 proceeds in a
fashion analogous to that with Ph2CdNNH2, but in this
case the main product 22 (see Scheme 6) could not be
completely separated from the diazoalkane derivative
8 and small amounts of other byproducts. Therefore,
1
compound 22 has been characterized by IR and H, 13C,
and 31P NMR spectroscopy.
Regarding the mechanism of formation of 21 and 22,
we assume that in the initial step a hydrazonerhodium-
(I) intermediate, in which the hydrazone is probably
coordinated via the CdN nitrogen atom, is generated.
Subsequent oxidative addition of a C-H bond of the
phenyl ring, being a well-known reaction also for
diphenylimine derivatives,24 would then afford the
ortho-metalated rhodium(III) complex. The question
whether the diazoalkane compound 3 or 8 is formed
from the supposed intermediate trans-[RhCl{H2-
NNdC(Ph)R}(PiPr3)2] or from the rhodium(III) com-
plexes 21 and 22 is open to speculation. When we
The isolated diazoalkane complexes 24, 25, 27, and
28 are green, microcrystalline solids which are more
stable in solution and toward oxygen than their chloro
counterparts. In addition to the broadened ν(N2C) mode
at 1920 cm-1, the IR spectra of 24 and 27 display
intense bands at around 3240-3280 and 1935 cm-1
,
which are assigned to the tCH and CtC stretching
vibrations. The ν(CtC) stretches of 25 and 28 appear
at 2070 and 2050 cm-1, respectively. Typical features
of the 13C NMR spectra of 24, 25, 27, and 28 are the
signal for the N2C carbon at δ 71-75 and the two low-
field resonances for the 13C nuclei of the alkynyl groups.
The latter are split into doublets of triplets due to 13C-
103Rh and 13C-31P couplings.
(23) (a) Collman, J . P.; Hegedus, L. S.; Norton, J . R.; Finke, R. G.
Principles and Applications of Organotransition Metal Chemistry;
University Science Books: Mill Valley, CA, 1987; Chapter 5. (b)
Tanaka, M.; Sakakura, T. Pure Appl. Chem. 1990, 62, 1147-1150. (c)
Boyd, S. E.; Field, L. D.; Partridge, M. G. J . Am. Chem. Soc. 1994,
116, 9492-9497. (d) Wang, K.; Goldman, M. E.; Emge, T. J .; Goldman,
A. S. J . Organomet. Chem. 1996, 518, 55-68. (e) Guari, Y.; Sabo-
Etienne, S.; Chaudret, B. Eur. J . Inorg. Chem. 1999, 1047-1055. (f)
Crabtree, R. H. J . Chem. Soc., Dalton Trans. 2001, 2437-2450.
(24) Review: Bruce, M. I. Angew. Chem. 1977, 89, 75-89; Angew.
Chem., Int. Ed. Engl. 1977, 16, 73-87.
(25) (a) Brandt, L.; Wolf, J .; Werner, H. J . Organomet. Chem. 1993,
444, 235-244. (b) Brandt, L. Dissertation, Universita¨t Wu¨rzburg, 1991.

Rh(I) Complexes with Diazoalkanes as Ligands
Organometallics, Vol. 22, No. 17, 2003 3571
Sch em e 8a
F igu r e 3. Molecular diagram of compound 31a (for
molecule A of the unit cell). Selected bond distances (Å)
and angles (deg): Rh(1)-P(1) ) 2.399(1), Rh(1)-P(2) )
2.372(1), Rh(1)-Cl(1) ) 2.350(1), Rh(1)-O(3) ) 2.043(3),
Rh(1)-N(2) ) 1.990(4), N(1)-N(2) ) 1.212(5), N(1)-C(51)
) 1.393(6), C(51)-C(52) ) 1.400(7), C(52)-O(3) ) 1.285-
(6); P(1)-Rh(1)-P(2) ) 165.32(5), Cl(1)-Rh(1)-O(3) )
173.7(1), P(1)-Rh(1)-Cl(1) ) 90.13(5), P(2)-Rh(1)-Cl(1)
) 88.89(4), P(1)-Rh(1)-O(3) ) 89.28(9), P(2)-Rh(1)-O(3)
) 90.10(9), O(3)-Rh(1)-N(2) ) 89.4(1), Rh(1)-N(2)-N(1)
) 123.6(3), N(2)-N(1)-C(51) ) 134.3(4), N(1)-C(51)-
C(52) ) 120.3(4), C(51)-C(52)-O(3) ) 124.7(4), C(52)-
O(3)-Rh(1) ) 127.1(3).
a
L ) PiPr3, R ) CH2CH(CH3)2.
Rh od iu m (I) Com p lexes w ith Dia zo Keton es a n d
Dia zo Keto Ester s a s Liga n d s. Under the same
conditions as used for the preparation of 17 and 18,
compound 2 also reacts with diazo ketones RC(O)C(Ph)-
N2 (R ) Ph, Me) by ligand exchange and formation of
the rhodium(I) complexes 29 and 30, respectively
(Scheme 8). The diazo keto ester RCH2C(O)C(CO2Me)-
N2 (R ) CH2CH(CH3)2) behaves similarly and, upon
treatment with 2, affords the corresponding rhodium-
(I) derivative 31. In each case the yield is good to
excellent. However, while for 29 and 30 the NMR
spectra confirm that only one product has been formed,
the NMR spectra of 31 leave no doubt that two species
(probably the isomers 31a and 31b) are present.
In attempting to separate the isomers by fractional
crystallization from pentane, single crystals were iso-
lated, which were investigated by an X-ray diffraction
analysis. There were two independent molecules A and
B in the unit cell, which differ in both the conformation
of the isopentyl fragment and the arrangement of the
isopropyl groups around the phosphorus atoms. The
structure of molecule A is depicted in Figure 3. Most
surprisingly, the rhodium center is not four- but five-
coordinated, the polyhedron corresponding to a slightly
distorted square pyramid. The basal plane of the
pyramid is built up by the two phosphorus atoms, still
in a trans disposition, and the chloride and the ketonic
oxygen atom, which are also trans to each other. The
apical position is occupied by the terminal nitrogen of
the diazo unit. While the axis P(1)-Rh(1)-P(2) is
somewhat bent, the bond angles around rhodium devi-
ate only marginally from the ideal 90° value. The
Rh(1)-N(2) distance of 1.990(4) Å is significantly length-
ened compared with 15 (1.836(5) Å) and 20 (1.788(6)
Å), probably being a consequence of the formation of the
chelate ring. This chelate ring is perfectly planar and
lies perpendicular to the plane containing Rh(1), Cl(1),
P(1), P(2), and O(3). The dihedral angle between the two
planes amounts to 89.30(8)°. Not only the Rh(1)-N(2)
distance but also the N(1)-N(2) bond length (1.212(5)
Å) is considerably longer than in 15 (1.150(6) Å) and
20 (1.144(8) Å), indicating that due to the bending Rh-
(1)-N(2)-N(1) of 134.3(4)° the N-N bond strength has
been reduced. Since the distances N(1)-C(51) and O(3)-
C(52) are longer than a normal NdC or CdO double
bond and the distance C(51)-C(52) shorter than a C-C
single bond, we assume that the π-electrons of the
chelate ring are mainly delocalized. It is conceivable that
also the ester group is part of the delocalized system,
because the atoms C(50), O(1), O(2), and C(58) lie in
the same plane as the six-membered chelate ring.
The reasons to believe that the structure of the diazo
ketone complexes 29 and 30 is similar to that of 31a
but different from that of 3-11 and 13-16 are as
follows. (1) Compounds 29, 30, and 31a are red, while
all the other rhodium(I) complexes (apart from 11 and
14) shown in Schemes 1-3 are green. (2) The chemical
shifts of the 31P NMR resonances for 29, 30, and 31a
(in C6D6 or C6D5CD3) are δ 31.0-32.3, while those for
1
3-11 and 13-15 (in C6D6) are δ 38.5-42.5. (3) The H
NMR spectra of 3-11 and 13-16 show only one signal
(doublet of virtual triplets) for the protons of the methyl
groups of the isopropyl units, whereas the spectra of 29
and 30 show two. Accordingly, the 13C NMR spectra of
29 and 30 display two singlets for the PCHCH3 carbon
atoms, whereas in the spectra of 3-11 and 13-16 there
is only one signal for the 13C nuclei of phosphine-CH3
units. (4) The chemical shifts of the 13C NMR signals
for the N2C carbon atoms of 29 and 30 (δ ca. 100-101)

3572 Organometallics, Vol. 22, No. 17, 2003
Werner et al.
differ by ca. 20-30 ppm from those of the related carbon
atoms of the diazoalkane compounds 3-7, 9-11, and
13-15. The positions at lower fields are consistent with
an increased delocalization of the π-electrons in the
postulated chelate ring.
Rh-Sb, leading to a more crowded coordination sphere
in the starting materials 1, 2, 23 and 26, prevents a
η2-N,N or η2-N,C coordination of the diazoalkane, which
possibly is the prerequisite for the generation of a metal
carbene.
The detection of the two species 31a and 31b in the
product of the reaction of 2 with the diazo keto ester
derivative RCH2C(O)C(CO2Me)N2 deserves additional
comment. The 1H NMR spectrum of the product (in
toluene-d8) displays at 253 K two signals for the OCH3
protons at δ 3.53 and 3.40 in the approximate ratio of
10:1. When the temperature is raised, the intensity
changes and at 313 K approaches a ratio of 1:2. The
situation in the 31P NMR spectra is similar. At 253 K
two doublets are observed at δ 42.6 and 31.0, the latter
of which dominates. At higher temperatures, the inten-
sity of the two signals changes, and above 303 K the
dominating one is that at δ ca. 43.5. These changes in
intensity observed with changes in temperature are
reversible. Taking the data for the four-coordinated
complexes 3-11 and 13-16 as well as those for the
presumably five-coordinated compounds 29 and 30 into
consideration, we conclude that the major species in
solution at lower temperatures is 31a and that at higher
temperatures is 31b. Since 31a dominates at 253 K and
below, it is not surprising that the single crystals, grown
from pentane at 195 K, contain only this isomer.
Although according to the NMR data there is no doubt
that in solution an equilibrium between 31a and 31b
Apart from the reactions of the diazoalkane complexes
3-7 and 14 toward ethene, which instead of disubsti-
tuted cyclopropanes give exclusively trisubstituted ole-
fins CH3CHdCRR′, the most unusual facet of our
studies is the formation of five-coordinated rhodium(I)
compounds with diazo ketones and a diazo keto ester
derivative as chelating ligands. This result deserves
particular attention insofar as (1) rhodium(I) strongly
prefers the coordination number 4 with a square-planar
geometry and (2) the donor capability of a ketonic
oxygen atom is not very pronounced. The formation of
a six-membered chelate ring in the complexes 29, 30,
and 31a seems to be the crucial driving force that
obviously overcomes the assumed strain of the RhN2C2O
system and thus leads to products with an 18-electron
count.
Exp er im en ta l Section
All reactions were carried out under an atmosphere of argon
by Schlenk techniques. The starting materials 1,7a 2,8a 19,26
23,27 and 2628 were prepared as described in the literature.
NMR spectra were recorded on Bruker WH 90, Bruker AC 200,
and Bruker AMX 400 instruments at room temperature, if not
otherwise stated. IR spectra were recorded on a Perkin-Elmer
1420 infrared spectrometer and mass spectra on a Finnigan
90 MAT instrument. Melting points were measured by DTA.
Abbreviations used are as follows: s, singlet; d, doublet; t,
triplet; q, quartet; m, multiplet; br, broadened signal. The term
vt indicates a virtual triplet, and N ) 3J (P,H) + 5J (P,H) or
1
exists, it was not possible, neither in the H nor in the
31P NMR spectra, to observe coalescence, since above
333 K both isomers decompose.
The diazo ketone PhCH2C(O)CHN2, which is some-
what similar in structure to the diazo keto ester
derivative, reacts with the starting material 2 less
selectively. In addition to the anticipated compound 32
(see Scheme 8), the dinitrogen complex 12 as well as
small amounts of unidentified byproducts (ca. 10%) are
formed, which could not be separated from 32. The ratio
of 32 to 12 was approximately 2:1. The 31P NMR
spectrum of 32 shows (in C6D6) only one set of signals
for the phosphorus atoms, indicating that only one
isomer is formed. The appearance of a multiplet instead
of one doublet of virtual triplets for the phosphine-
methyl protons and, even more, the chemical shift of δ
31.1 (31a : δ 31.6) for the 31P NMR signal suggests that,
as in the case of 29, 30, and 31a , also in 32 the rhodium
is five-coordinated and the diazo ketone is bonded as a
chelating ligand.
3
1J (P,C) + J (P,C).
Rea ction of Com p ou n d 1 w ith CH2N2. A solution of 1
(110 mg, 0.12 mmol) in diethyl ether (10 mL) was treated
dropwise with a 0.1 M solution of CH2N2 in diethyl ether (2.5
mL, 0.25 mmol) at room temperature. A rapid evolution of gas
(N2) occurred. The solvent was evaporated in vacuo, and the
residue was recrystallized from toluene/pentane (1:10). A
yellow microcrystalline solid was obtained, which was shown
by comparison of the 1H and 31P NMR spectra with those of
an authentic sample to be trans-[RhCl(C2H4)(PiPr3)2] (2).8a
Yield: 111 mg (94%).
P r ep a r a tion of tr a n s-[Rh Cl(N2CP h 2)(P iP r 3)2] (3). A
solution of 1 (335 mg, 0.37 mmol) in diethyl ether (20 mL) was
treated at -50 °C with a solution of Ph2CN2 (142 mg, 0.73
mmol) in diethyl ether (5 mL). The solution was slowly warmed
to room temperature, which led to a change of color from violet
to green. After the solution was stirred at ca. 20 °C for 10 min,
it was concentrated to ca. 5 mL and then layered with pentane
(30 mL). The mixture was stored at -78 °C for 12 h, which
led to the precipitation of green air-sensitive crystals. They
were separated from the mother liquor, washed twice with
small amounts of pentane (0 °C), and dried: yield 368 mg
(77%); mp 94 °C dec. Anal. Calcd for C31H52ClN2P2Rh: C,
57.01; H, 8.03; N, 4.29. Found: C, 56.35; H, 8.26; N, 3.99. IR
Con clu sion s
The work presented in this paper has shown that a
variety of diazoalkanes RR′CN2, which upon treatment
with trans-[RhCl(C2H4)(SbiPr3)2] (19) afford the corre-
sponding rhodium(I) carbenes trans-[RhCl(dCRR′)-
(SbiPr3)2],5 react with either the dimer [RhCl(PiPr3)2]2
(1) or the ethene derivatives trans-[RhX(C2H4)(PiPr3)2]
(2, 23, 26) to give complexes such as 3-11, 13-18, 24,
25, 27, and 28, in which the intact diazoalkane is
coordinated via the terminal nitrogen atom to the metal
center. It thus appears that PiPr3, as the better σ-donor
ligand compared with SbiPr3, hinders the elimination
of N2 and stabilizes the Rh-N2CRR′ bond. It is conceiv-
able that also the smaller distance Rh-P compared with
(KBr): ν(N2C) 1940 (br) cm-1 1H NMR (200 MHz, C6D6): δ
.
7.20 (br m, 10 H, C6H5), 2.35 (m, 6 H, PCHCH3), 1.26 (dvt, N
) 13.3, J (H,H) ) 7.1 Hz, 36 H, PCHCH3). 13C NMR (50.3 MHz,
C6D6): δ 129.5, 128.9, 125.1, 124.3 (all s, C6H5), 78.7 (br s,
(26) Werner, H.; Schwab, P.; Mahr, N.; Wolf, J . Chem. Ber. 1992,
125, 2641-2650.
(27) Scha¨fer, M.; Wolf, J .; Werner, H. J . Organomet. Chem. 1995,
485, 85-100.
(28) Scha¨fer, M. Dissertation, Universita¨t Wu¨rzburg, 1994.

Rh(I) Complexes with Diazoalkanes as Ligands
Organometallics, Vol. 22, No. 17, 2003 3573
N2C), 23.6 (vt, N ) 18.2 Hz, PCHCH3), 20.0 (s, PCHCH3). 31P
NMR (81.0 MHz, C6D6): δ 38.5 (d, J (Rh,P) ) 118.5 Hz).
P r ep a r a tion of tr a n s-[Rh Cl{N2C(p-Tol)2}(P iP r 3)2] (4).
This compound was prepared as described for 3 from 1 (85
mg, 0.09 mmol) and (p-Tol)2CN2 (42 mg, 0.18 mmol) in diethyl
ether (8 mL): dark green solid; yield 102 mg (83%); mp 86 °C
dec. Anal. Calcd for C33H56ClN2P2Rh: C, 58.19; H, 8.29; N,
4.11. Found: C, 58.18; H, 8.43; N, 4.10. IR (KBr): ν(N2C) 1941
Hz, 36 H, PCHCH3). 31P NMR (81.0 MHz, C6D6): δ 40.6 (d,
J (Rh,P) ) 123.0 Hz).
P r ep a r a tion of tr a n s-[Rh Cl{N2C(CH2P h )P h }(P iP r 3)2]
(9). This compound was prepared as described for 3 from 1
(50 mg, 0.055 mmol) and PhCH2C(Ph)N2 (23 mg, 0.11 mmol)
in diethyl ether (6 mL): dark green solid; yield 70 mg (95%);
mp 64 °C dec. Anal. Calcd for C32H54ClN2P2Rh: C, 58.23; H,
8.33; N, 4.08. Found: C, 57.62; H, 8.16; N, 4.20. IR (KBr):
(br) cm-1. H NMR (200 MHz, C6D6): δ 7.34, 7.01 (both m, 4
ν(N2C) 1940 (br) cm-1 1H NMR (200 MHz, C6D6): δ 7.14-
.
1
H each, C6H4), 2.35 (m, 6 H, PCHCH3), 2.13 (s, 6 H, C6H4CH3),
1.26 (dvt, N ) 13.3, J (H,H) ) 6.9 Hz, 36 H, PCHCH3). 13C
NMR (50.3 MHz, C6D6): δ 133.7, 129.7, 126.4, 125.3 (all s,
C6H4), 78.5 (br s, N2C), 23.6 (vt, N ) 17.6 Hz, PCHCH3), 20.9
(s, C6H4CH3), 20.1 (s, PCHCH3). 31P NMR (81.0 MHz, C6D6):
δ 41.7 (d, J (Rh,P) ) 120.6 Hz).
6.93 (br m, 10 H, C6H5), 3.82 (br s, 2 H, CH2Ph), 2.32 (m, 6 H,
PCHCH3), 1.25 (dvt, N ) 13.9, J (H,H) ) 7.1 Hz, 36 H,
PCHCH3). 13C NMR (50.3 MHz, C6D6): δ 140.8, 138.0 (both s,
ipso-C of C6H5), 132.0, 128.7, 128.1, 126.6, 122.2, 121.5 (all s,
C6H5), 72.2 (br s, N2C), 28.5 (s, CH2Ph), 23.4 (vt, N ) 18.0 Hz,
PCHCH3), 20.0 (s, PCHCH3). 31P NMR (81.0 MHz, C6D6): δ
40.5 (d, J (Rh,P) ) 120.0 Hz).
P r ep a r a tion of tr a n s-[Rh Cl{N2C(CF 3)P h }(P iP r 3)2] (10).
This compound was prepared as described for 3 from 1 (92
mg, 0.10 mmol) and CF3C(Ph)N2 (37 mg, 0.20 mmol) in diethyl
ether (8 mL): green air-stable solid; yield 120 mg (93%); mp
83 °C. Anal. Calcd for C26H47ClF3N2P2Rh: C, 47.91; H, 7.64;
N, 4.47. Found: C, 48.42; H, 7.34; N, 4.34. IR (KBr): ν(N2C)
1935 (br) cm-1. 1H NMR (200 MHz, C6D6): δ 7.22-7.05 (br m,
5 H, C6H5), 2.32 (m, 6 H, PCHCH3), 1.22 (dvt, N ) 13.5, J (H,H)
) 7.2 Hz, 36 H, PCHCH3). 13C NMR (50.3 MHz, C6D6): δ 128.9,
125.1, 123.5, 121.7 (all s, C6H5), 121.7 (q, J (C,F) ) 268.5 Hz,
CF3), 65.9 (br s, N2C), 23.8 (vt, N ) 19.1 Hz, PCHCH3), 19.9
(s, PCHCH3). 19F NMR (84.2 MHz, C6D6): δ -56.2 (s). 31P NMR
(81.0 MHz, C6D6): δ 40.8 (d, J (Rh,P) ) 115.7 Hz).
P r epar ation of tr a n s-[Rh Cl{N2C(p-Tol)P h }(P iP r 3)2] (5).
This compound was prepared as described for 3 from 1 (155
mg, 0.17 mmol) and Ph(p-Tol)CN2 (70 mg, 0.34 mmol) in
diethyl ether (8 mL): dark green solid; yield 196 mg (87%);
mp 91 °C dec. Anal. Calcd for C32H54ClN2P2Rh: C, 57.62; H,
8.16; N, 4.19. Found: C, 57.30; H, 8.43; N, 3.93. IR (KBr):
ν(N2C) 1937 (br) cm-1 1H NMR (200 MHz, C6D6): δ 7.90-
.
7.08 (br m, 9 H, C6H5 and C6H4), 2.38 (m, 6 H, PCHCH3), 2.12
(s, 3 H, C6H4CH3), 1.25 (dvt, N ) 14.4, J (H,H) ) 7.1 Hz, 36 H,
PCHCH3). 13C NMR (50.3 MHz, C6D6): δ 140.1 (s, ipso-C of
C6H4), 131.7, 130.3, 128.2, 125.5, 122.2, 121.0, 118.6 (all s, C6H5
and C6H4), 74.4 (br s, N2C), 24.8 (vt, N ) 19.5 Hz, PCHCH3),
22.7 (s, C6H4CH3), 20.2 (s, PCHCH3). 31P NMR (81.0 MHz,
C6D6): δ 41.8 (d, J (Rh,P) ) 129.4 Hz).
P r epar ation of tr a n s-[Rh Cl{N2C(CO2Et)2}(P iP r 3)2] (11).
This compound was prepared similarly as described for 3 from
1 (85 mg, 0.09 mmol) and N2C(CO2Et)2 (34 mg, 0.18 mmol) in
toluene (5 mL) at room temperature. After recrystallization
from toluene/pentane (1:3) at -78 °C, red air-stable crystals
were obtained: yield 95 mg (80%); mp 145 °C dec. Anal. Calcd
for C25H52ClN2O4P2Rh: C, 46.55; H, 8.12; N, 4.34. Found: C,
46.29; H, 7.86; N, 4.04. IR (KBr): ν(N2C) 1945 (br), ν(CdO)
P r ep a r a tion of tr a n s-[Rh Cl{N2C(o-Tol)P h }(P iP r 3)2] (6).
This compound was prepared as described for 3 from 1 (150
mg, 0.16 mmol) and Ph(o-Tol)CN2 (68 mg, 0.33 mmol) in
diethyl ether (8 mL): dark green solid; yield 121 mg (55%);
mp 101 °C dec. Anal. Calcd for C32H54ClN2P2Rh: C, 57.61; H,
8.16; N, 4.19. Found: C, 57.66; H, 8.24; N, 3.98. IR (KBr):
ν(N2C) 1936 (br) cm-1 1H NMR (200 MHz, C6D6): δ 7.43-
.
6.83 (br m, 9 H, C6H5 and C6H4), 2.37 (m, 6 H, PCHCH3), 2.15
(s, 3 H, C6H4CH3), 1.27 (dvt, N ) 13.1, J (H,H) ) 6.9 Hz, 36 H,
PCHCH3). 13C NMR (50.3 MHz, C6D6): δ 150.6 (s, ipso-C of
C6H4), 134.0, 130.7, 128.9, 128.3, 126.0, 125.6, 124.8, 124.1 (all
s, C6H5 and C6H4), 78.5 (br s, N2C), 23.6 (vt, N ) 18.5 Hz,
PCHCH3), 20.9 (s, C6H4CH3), 20.0 (s, PCHCH3). 31P NMR (81.0
MHz, C6D6): δ 41.7 (d, J (Rh,P) ) 122.2 Hz).
1
1730 cm-1. H NMR (90 MHz, C6D6): δ 4.16 (q, J (H,H) ) 7.2
Hz, 2 H, CH2CH3), 2.37 (m, 6 H, PCHCH3), 1.26 (dvt, N ) 13.3,
J (H,H) ) 7.2 Hz, 36 H, PCHCH3), 1.06 (t, J (H,H) ) 7.2 Hz,
CH2CH3). 13C NMR (50.3 MHz, C6D6): δ 159.8 (s, CO2Et), 76.3
(br s, N2C), 59.9 (s, CH2CH3), 23.8 (vt, N ) 19.5 Hz, PCHCH3),
19.9 (s, PCHCH3), 14.8 (s, CH2CH3). 31P NMR (81.0 MHz,
C6D6): δ 42.4 (d, J (Rh,P) ) 114.6 Hz).
F or m a tion of tr a n s-[Rh Cl(N2)(P iP r 3)2] (12). A solution
of 1 (61 mg, 0.065 mmol) in diethyl ether (5 mL) was treated
at -50 °C with CH(CO2Et)N2 (15 mg, 0.13 mmol). The solution
was slowly warmed to room temperature, which led to a
change of color from violet to brown. After the solution was
stirred at ca. 20 °C for 10 min, it was concentrated to ca. 5
mL and then layered with pentane (15 mL). The mixture was
stored at -78 °C for 12 h, which led to the precipitation of a
pale brown microcrystalline solid. This was shown by com-
parison of the IR and 31P NMR data to be 12.8a,13
P r ep a r a tion of tr a n s-[Rh Cl{N2C(p-C6H4Cl)2}(P iP r 3)2]
(7). This compound was prepared as described for 3 from 1
(92 mg, 0.10 mmol) and (p-C6H4Cl)2CN2 (53 mg, 0.20 mmol)
in diethyl ether (7 mL): dark green solid; yield 114 mg (78%);
mp 114 °C dec. Anal. Calcd for C31H50Cl3N2P2Rh: C, 51.57;
H, 6.98; N, 3.88. Found: C, 51.89; H, 7.17; N, 4.17. IR (KBr):
ν(N2C) 1934 (br) cm-1 1H NMR (200 MHz, C6D6): δ 7.32-
.
6.89 (br m, 8 H, C6H4), 2.13 (m, 6 H, PCHCH3), 1.07 (dvt, N )
13.5, J (H,H) ) 6.9 Hz, 36 H, PCHCH3). 13C NMR (50.3 MHz,
C6D6): δ 129.4, 129.1, 127.7, 126.9 (all s, C6H4), 76.5 (br s,
N2C), 23.6 (vt, N ) 18.5 Hz, PCHCH3), 20.0 (s, PCHCH3). 31P
NMR (81.0 MHz, C6D6): δ 42.1 (d, J (Rh,P) ) 119.2 Hz).
P r ep a r a tion of tr a n s-[Rh Cl{N2C(CH3)P h }(P iP r 3)2] (8).
A solution of 1 (45 mg, 0.05 mmol) in diethyl ether (5 mL) was
treated dropwise at -78 °C with a solution of CH3C(Ph)N2 (13
mg, 0.10 mmol) in diethyl ether (2 mL). The solution was
slowly warmed to -30 °C, which led to a change of color from
violet to green. After the solution was stirred for 5 min, it was
concentrated to ca. 1 mL and then layered with pentane (5
mL). The mixture was then stored at -78 °C for 2 h, which
led to the precipitation of light green air-sensitive crystals.
They were separated from the mother liquor, washed twice
with small amounts of pentane (-20 °C), and dried: yield 53
mg (89%); mp 42 °C dec. Anal. Calcd for C26H50ClN2P2Rh: C,
53.17; H, 8.81; N, 4.54. Found: C, 52.84; H, 8.52; N, 4.74. IR
P r ep a r a tion of tr a n s,tr a n s-[{Rh Cl(P iP r 3)2}2{µ-C6H4-
(C(P h )N2)2}] (13). This compound was prepared as described
for 3 from 1 (53 mg, 0.06 mmol) and 1,4-C6H4{C(Ph)N2}2 (18
mg, 0.06 mmol) in diethyl ether (8 mL): olive green air-stable
solid; yield 61 mg (86%); mp 82 °C. Anal. Calcd for C56H98
-
Cl2N4P4Rh2: C, 55.24; H, 8.26; N, 4.58. Found: C, 54.77; H,
1
8.04; N, 4.56. IR (KBr): ν(N2C) 1934 (br) cm-1. H NMR (200
MHz, C6D6): δ 7.50-6.87 (br m, 14 H, C6H5 and C6H4), 2.39
(m, 6 H, PCHCH3), 1.29 (dvt, N ) 13.3, J (H,H) ) 7.2 Hz, 36
H, PCHCH3). 13C NMR (50.3 MHz, C6D6): δ 129.4, 128.9,
128.3, 125.6, 125.1, 124.3 (all s, C6H5 and C6H4), 78.8 (br s,
N2C), 23.6 (vt, N ) 18.4 Hz, PCHCH3), 20.1 (s, PCHCH3). 31P
NMR (81.0 MHz, C6D6): δ 40.7 (d, J (Rh,P) ) 122.6 Hz).
P r ep a r a t ion of tr a n s-[R h Cl(N2CC12H 8)(P iP r 3)2] (14).
This compound was prepared as described for 3 from 1 (164
mg, 0.18 mmol) and 9-diazofluorene (68 mg, 0.36 mmol) in
diethyl ether (8 mL): red-brown air-stable solid; yield 204 mg
(KBr): ν(N2C) 1935 (br) cm-1 1H NMR (200 MHz, C6D6): δ
.
7.30-6.94 (br m, 5 H, C6H5), 2.36 (m, 6 H, PCHCH3), 2.15 (t,
J (P,H) ) 1.3 Hz, N2CCH3), 1.29 (dvt, N ) 13.1, J (H,H) ) 7.1

3574 Organometallics, Vol. 22, No. 17, 2003
Werner et al.
(88%); mp 36 °C. Anal. Calcd for C31H50ClN2P2Rh: C, 57.19;
H, 7.74; N, 4.30. Found: C, 57.53; H, 8.01; N, 4.30. IR (KBr):
ν(N2C) 1915 (br) cm-1. 1H NMR (200 MHz, C6D6): δ 7.86 (ddd,
J (H,H) ) 7.8, 1,1 and 0.7 Hz, 2 H, H1 and H8), 7.63 (br d,
J (H,H) ) 7.8 Hz, 2 H, H4 and H5), 7.35, 7.10 (both ddd, J (H,H)
) 7.8, 7.6 and 1.1 Hz, 2 H each, H2, H7 and H3, H6), 2.30 (m,
6 H, PCHCH3), 1.19 (dvt, N ) 13.7, J (H,H) ) 7.1 Hz, 36 H,
PCHCH3); the protons are numbered clockwise beginning at
the ortho position next to the five-membered ring. 13C NMR
(50.3 MHz, C6D6): δ 131.2, 128.3, 125.5, 122.6, 121.0, 118.7
(all s, C6H4), 68.5 (br s, N2C), 23.7 (vt, N ) 19.5 Hz, PCHCH3),
19.9 (s, PCHCH3). 31P NMR (81.0 MHz, C6D6): δ 43.8 (d,
J (Rh,P) ) 116.3 Hz).
19.4 Hz, PCHCH3), 19.8 (s, PCHCH3). 31P NMR (81.0 MHz,
CDCl3): δ 41.9 (d, J (Rh,P) ) 114.3 Hz).
P r ep a r a tion of tr a n s-[Rh Cl(N2C5Cl4)(SbiP r 3)2] (20). A
solution of 19 (73 mg, 0.11 mmol) in pentane (10 mL) was
cooled to -78 °C and treated with a solution of tetrachlorodi-
azocyclopentadiene (50 mg, 0.22 mmol) in diethyl ether (5 mL).
A change of color from orange-brown to green occurred. After
the solution was warmed to room temperarure, the solvent was
evaporated in vacuo. The olive green residue was washed twice
with methanol (3 mL each) and once with pentane (5 mL) and
dried. From the combined washings 1 equiv of N2C5Cl4 could
be reisolated. Yield of 20: 75 mg (79%). Mp: 104 °C dec. Anal.
Calcd for C23H42Cl5N2RhSb2: C, 31.74; H, 4.86; N, 3.22; Rh,
11.82. Found: C, 31.62; H, 5.07; N, 3.20; Rh, 11.87. IR (KBr):
P r ep a r a tion of tr a n s-[Rh Cl(N2CC13H8O)(P iP r 3)2] (15).
This compound was prepared similarly as described for 3 from
1 (85 mg, 0.09 mmol) and 9,10-anthraquinone-9-diazide (40
mg, 0.18 mmol) in toluene (5 mL) at room temperature: green
air-stable solid; yield 112 mg (89%); mp 138 °C dec. Anal. Calcd
for C32H50ClN2OP2Rh: C, 56.60; H, 7.42; N, 4.13. Found: C,
56.84; H, 7.26; N, 4.34. IR (KBr): ν(N2C) 2083, ν(CdO) 1618
ν(N2C) 1942 cm-1 1H NMR (400 MHz, C6D6): δ 2.20 (sept,
.
J (H,H) ) 7.3 Hz, 6 H, SbCHCH3), 1.27 (d, J (H,H) ) 7.3 Hz,
36 H, SbCHCH3). 13C NMR (100.6 MHz, C6D6): δ 109.3, 102.5
(both s, C4Cl4), 77.0 (s, N2C), 22.0 (s, SbCHCH3), 20.2 (br s,
SbCHCH3).
Rea ction s of Com p ou n d s 3-7 a n d 14 w ith Eth en e. A
slow stream of ethene was passed through a solution of the
diazoalkane complex (ca. 0.04 mmol) in C6D6 for 30 s at room
temperature. After the solution was warmed to 40 °C and
stirred for 1 h, the composition of the reaction mixture was
investigated by 1H NMR spectroscopy. In addition to the
resonances of compound 2, only signals corresponding to the
C-C coupling products CH3CHdCRR′ (R ) R′ ) Ph; R ) R′ )
p-Tol; R ) Ph, R′ ) p-Tol; R ) Ph, R′ ) o-Tol; R ) R′ ) p-C6H4-
Cl; R,R′ ) C12H8) could be observed. For 11 and 15 as starting
materials, no reaction with ethene could be detected.
P r ep a r a t ion of [R h (H )Cl{K2-C,N-C6H 4C(NNH 2)P h }-
(P iP r 3)2] (21). A solution of 1 (90 mg, 0.095 mmol) in toluene
(5 mL) was treated with a solution of diphenyl hydrazone (39
mg, 0.19 mmol) in toluene (2 mL) and stirred for 30 min at
room temperature. A change of color from violet to red-brown
occurred. The solvent was evaporated in vacuo and the residue
extracted with pentane (20 mL). The extract was concentrated
to ca. 3 mL in vacuo and then stored for 12 h at -78 °C. A
light brown microcrystalline solid precipitated, which was
separated from the mother liquor, washed twice with small
amounts of pentane (0 °C), and dried. The mother liquor
consisted mainly of 21 and the diazoalkane complex 3. Yield
1
cm-1. H NMR (90 MHz, C6D6): δ 8.78, 7.54 (both m, 8 H, 2x
C6H4), 2.73 (m, 6 H, PCHCH3), 1.60 (dvt, N ) 13.8, J (H,H) )
7.2 Hz, 36 H, PCHCH3). 13C NMR (50.3 MHz, C6D6): δ 178.9
(s, CdO), 133.7, 131.3, 130.3, 129.3, 128.6, 128.1, 127.9, 127.1,
124.7, 123.2, 121.7 (all s, 2 × C6H4), 75.7 (br s, N2C), 24.1 (vt,
N ) 19.4 Hz, PCHCH3), 19.9 (s, PCHCH3). 31P NMR (81.0
MHz, C6D6): δ 42.5 (d, J (Rh,P) ) 114.3 Hz).
P r ep a r a tion of tr a n s-[Rh Cl(N2CC10H8O)(P iP r 3)2] (16).
This compound was prepared as described for 3 from 1 (85
mg, 0.09 mmol) and 3-methyl-1,4-naphthoquinone-1-diazide
(33 mg, 0.18 mmol) in toluene (5 mL) at room temperature:
green air-stable solid; yield 94 mg (79%); mp 127 °C dec. Anal.
Calcd for C29H50ClN2OP2Rh: C, 54.17; H, 7.84; N, 4.36.
Found: C, 54.43; H, 7.55; N, 4.40. IR (KBr): ν(N2C) 2088,
ν(CdO) 1635 cm-1 1H NMR (90 MHz, CDCl3): δ 8.33, 7.19
.
(both m, 5 H, C6H4 and CH), 2.37 (m, 6 H, PCHCH3), 2.15 (s,
3 H, CH3), 1.25 (dvt, N ) 13.9, J (H,H) ) 7.1 Hz, 36 H,
PCHCH3). 13C NMR (50.3 MHz, C6D6): δ 178.8 (s, CdO), 131.4,
129.7, 129.1, 128.7, 128.1, 127.9, 124.2, 121.8 (all s, C6H4, CH
and CCH3), 106.9 (br s, N2C), 23.9 (vt, N ) 19.6 Hz, PCHCH3),
18.9 (s, PCHCH3), 17.6 (s, CCH3). 31P NMR (81.0 MHz,
CDCl3): δ 42.9 (d, J (Rh,P) ) 112.8 Hz).
P r ep a r a t ion of tr a n s-[R h Cl(N2C5Cl4)(P iP r 3)2] (17). A
solution of 2 (90 mg, 0.18 mmol) in toluene (5 mL) was treated
with tetrachlorodiazocyclopentadiene (41 mg, 0.18 mmol) and
stirred for 3 h at room temperature. A change of color from
yellow to deep green occurred. The solvent was evaporated in
vacuo, and the residue was washed three times with pentane
(5 mL each) and recrystallized from toluene/pentane (1:3).
After the solution was stored at -78 °C, deep green air-stable
crystals precipitated, which were separated from the mother
liquor, washed twice with small amounts of pentane, and
dried: yield 117 mg (92%); mp 172 °C dec. Anal. Calcd for
of 21: 90 mg (70%). Mp: 133 °C dec. Anal. Calcd for C31H54-
ClN2P2Rh: C, 56.84; H, 8.31; N, 4.28. Found: C, 57.37; H, 8.07;
N, 4.64. MS (EI): m/z 458 [Rh(PiPr3)2Cl+], 195 [NH2NC(Ph)-
C6H4+]. IR (KBr): ν(NH) 3360, 3248 (both br), ν(RhH) 2104
1
cm-1. H NMR (200 MHz, C6D6): δ 7.72, 7.53 (both d, J (H,H)
) 7.3 Hz, 1 H each, o-H of C6H4), 7.40 (m, 2 H, C6H5), 7.27-
6.70 (br m, 5 H, C6H4 and C6H5), 5.12 (br s, 2 H, NH2), 2.16
(m, 6 H, PCHCH3), 1.30 (dvt, N ) 13.1, J (H,H) ) 7.3 Hz, 18
H, PCHCH3), 1.10 (dvt, N ) 14.5, J (H,H) ) 7.3 Hz, 18 H,
PCHCH3), -14.22 (dt, J (Rh,H) ) 14.5, J (P,H) ) 14.5 Hz, 1 H,
RhH). 13C NMR (50.3 MHz, C6D6): δ 167.2 (dt, J (Rh,C) ) 31.8,
J (P,C) ) 8.9 Hz, RhC), 155.9 (s, CdN), 146.6, 140.0, 133.3,
129.5, 129.1, 129.0, 128.3, 127.0, 126.7, 125.8, 120.8 (all s, C6H4
and C6H5), 24.9 (vt, N ) 21.6 Hz, PCHCH3), 19.6, 19.4 (both
s, PCHCH3). 31P NMR (81.0 MHz, C6D6): δ 36.9 (d, J (Rh,P) )
109.0 Hz; dd in off-resonance).
C
23H42Cl5N2P2Rh: C, 40.11; H, 6.15; N, 4.07. Found: C, 40.23;
H, 5.93; N, 4.25. IR (KBr): ν(N2C) 1997 cm-1 1H NMR (90
.
MHz, C6D6): δ 2.43 (m, 6 H, PCHCH3), 1.28 (dvt, N ) 14.1,
J (H,H) ) 7.1 Hz, 36 H, PCHCH3). 13C NMR (50.3 MHz,
C6D6): δ 109.3, 102.1 (both s, C4Cl4), 83.7 (br s, N2C), 23.8 (vt,
N ) 20.1 Hz, PCHCH3), 19.5 (s, PCHCH3). 31P NMR (81.0
MHz, CDCl3): δ 43.9 (d, J (Rh,P) ) 109.9 Hz).
P r ep a r a tion of [Rh (H)Cl{K2-C,N-C6H4C(NNH 2)CH3}-
(P iP r 3)2] (22). This compound was prepared as described for
21 from 1 (97 mg, 0.105 mmol) and PhC(CH3)dNNH2 (28 mg,
0.21 mmol) in toluene (5 mL). After extraction of the residue
with pentane, a brown oil was obtained, which contained in
addition to 22 small amounts of byproducts. Attempts to
separate the components failed. Spectroscopic data for 22 are
as follows. IR (KBr): ν(NH) 3380, 3280 (both br), ν(RhH) 2090
P r epar ation of tr a n s-[Rh Cl(N2C5P h 4)(P iP r 3)2] (18). This
compound was prepared as described for 17 from 2 (90 mg,
0.18 mmol) and tetraphenyldiazocyclopentadiene (71 mg, 0.18
mmol) in toluene (5 mL): brown-yellow air-stable solid; yield
136 mg (86%); mp 154 °C. Anal. Calcd for C47H62ClN2P2Rh:
C, 66.00; H, 7.31; N, 3.28. Found: C, 65.99; H, 7.09; N, 2.99.
IR (KBr): ν(N2C) 2058 cm-1
.
1H NMR (90 MHz, CDCl3): δ
cm-1. H NMR (200 MHz, C6D6): δ 7.75, 7.09 (both d, J (H,H)
1
7.37-6.93 (br m, 20 H, C6H5), 2.47 (m, 6 H, PCHCH3), 1.31
(dvt, N ) 13.8, J (H,H) ) 7.2 Hz, 36 H, PCHCH3). 13C NMR
(50.3 MHz, C6D6): δ 137.8, 137.3, 132.1, 130.2, 128.6, 127.9,
126.1, 125.6, 125.1 (all s, C6H5), 94.5 (br s, N2C), 24.2 (vt, N )
) 7.3 Hz, 2 H each, o-H and m-H of C6H4), 4.79 (br s, 2 H,
NH2), 2.40 (m, 6 H, PCHCH3), 1.54 (s, 3 H, CCH3), 1.35 (dvt,
N ) 13.1, J (H,H) ) 7.2 Hz, 18 H, PCHCH3), 0.96 (dvt, N )
14.3, J (H,H) ) 7.2 Hz, 18 H, PCHCH3), -14.23 (dt, J (Rh,H)

Rh(I) Complexes with Diazoalkanes as Ligands
Organometallics, Vol. 22, No. 17, 2003 3575
IR (hexane): ν(CtC) 2070, ν(N2C) 1930 (br) cm-1 1H NMR
) 14.6, J (P,H) ) 13.0 Hz, 1 H, RhH). 13C NMR (50.3 MHz,
C6D6): δ 167.5 (dt, J (Rh,C) ) 32.3, J (P,C) ) 8.8 Hz, RhC),
156.2 (s, CdN), 145.9, 139.0, 127.1, 123.7, 125.8, 120.7 (all s,
C6H4), 24.6 (vt, N ) 20.3 Hz, PCHCH3), 19.5, 19.1 (both s,
PCHCH3), 11.9 (s, CCH3). 31P NMR (81.0 MHz, C6D6): δ 37.3
(d, J (Rh,P) ) 110.4 Hz; dd in off-resonance).
Attem p ted Con ver sion of Com p ou n d 21 to 3. A solution
of 21 (106 mg, 0.16 mmol) in hexane (2 mL) was poured onto
a column filled with Al2O3 (neutral, activity grade V, length
of column 5 cm). With hexane, a green fraction was eluted
which consisted of 3 and the dinitrogen complex 12. Subse-
quent elution with toluene afforded a brownish fraction in
which, besides small amounts of 21, only unidentified products
could be detected.
.
(200 MHz, C6D6): δ 7.44-6.81 (br m, 10 H, C6H5), 2.42 (m, 6
H, PCHCH3), 1.28 (dvt, N ) 15.2, J (H,H) ) 6.9 Hz, 36 H,
PCHCH3), 1.26 (s, 9 H, CCH3). 13C NMR (50.3 MHz, C6D6): δ
136.8 (dt, J (Rh,C) ) 14.4, J (P,C) ) 3.2 Hz, CtCtBu), 130.3,
129.0, 124.7, 124.0 (all s, C6H5), 98.5 (dt, J (Rh,C) ) 51.3, J (P,C)
) 20.8 Hz, CtCtBu), 75.2 (br s, N2C), 32.6 (s, CCH3), 29.8 (s,
CCH3), 24.7 (vt, N ) 18.5 Hz, PCHCH3), 20.4 (s, PCHCH3).
31P NMR (81.0 MHz, C6D6): δ 46.9 (d, J (Rh,P) ) 132.2 Hz).
P r ep a r a tion of tr a n s-[Rh (CtCtBu )(N2CC12H8)(P iP r 3)2]
(28). This compound was prepared as described for 24 from
26 (97 mg, 0.18 mmol) and C12H8CN2 (35 mg, 0.18 mmol) in
pentane (8 mL). After recrystallization from acetone at -30
°C green, slightly air-sensitive crystals were obtained: yield
104 mg (82%); mp 109 °C dec. Anal. Calcd for C37H59N2P2Rh:
C, 63.78; H, 8.89; N, 4.02. Found: C, 63.92; H, 8.80; N, 3.97.
MS (EI): m/z 696 [M+], 504 [M+ - C12H8CN2]. IR (C6H6):
P r epar ation of tr a n s-[Rh (CtCH)(N2CP h 2)(P iP r 3)2] (24).
A solution of 23 (65 mg, 0.13 mmol) in pentane (5 mL) was
treated at -30 °C with a solution of Ph2CN2 (26 mg, 0.13 mmol)
in pentane (2 mL). The solution was slowly warmed to room
temperature, which led to the precipitation of a finely divided
green solid. After the solution was stirred at ca. 20 °C for 10
min, the solvent was evaporated in vacuo and the residue
recrystallized from pentane (10 mL) at -78 °C. Green mod-
erately air-sensitive crystals were formed, which were sepa-
rated from the mother liquor, washed twice with small
amounts of pentane (0 °C), and dried: yield 70 mg (80%); mp
35 °C dec. Anal. Calcd for C33H53N2P2Rh: C, 61.68; H, 8.31;
N, 4.36. Found: C, 61.42; H, 8.30; N, 4.01. MS (EI): m/z 642
[M+], 448 [M+ - Ph2CN2]. IR (hexane): ν(tCH) 3280, ν(CtC)
ν(CtC) 2050, ν(N2C) 1930 (br) cm-1 1H NMR (200 MHz,
.
C6D6): δ 7.88 (br d, J (H,H) ) 7.7 Hz, 2 H, H1 and H8), 7.67 (br
d, J (H,H) ) 7.9 Hz, 2 H, H4 and H5), 7.34, 7.10 (both ddd,
J (H,H) ) 7.9, 7.7 and 1.1 Hz, 2 H each, H2, H7 and H3, H6),
2.42 (m, 6 H, PCHCH3), 1.25 (dvt, N ) 13.5, J (H,H) ) 7.1 Hz,
36 H, PCHCH3), 1.22 (s, 9 H, CCH3); the protons are numbered
clockwise beginning at the ortho position next to the five-
membered ring. 13C NMR (50.3 MHz, C6D6): δ 139.9 (dt,
J (Rh,C) ) 13.9, J (P,C) ) 3.2 Hz, CtCtBu), 130.3, 129.4, 125.5,
122.2, 121.0, 118.5 (all s, C6H4), 98.0 (dt, J (Rh,C) ) 51.8, J (P,C)
) 21.3 Hz, CtCtBu), 74.4 (br s, N2C), 32.4 (s, CCH3), 29.7 (s,
CCH3), 24.8 (vt, N ) 19.4 Hz, PCHCH3), 20.3 (s, PCHCH3).
31P NMR (81.0 MHz, C6D6): δ 48.2 (d, J (Rh,P) ) 129.3 Hz).
P r epar ation of [Rh Cl{K2-N,O-N2C(P h )C(O)P h )}(P iP r 3)2]
(29). A solution of 2 (90 mg, 0.18 mmol) in toluene (5 mL) was
treated with PhC(O)C(Ph)N2 (40 mg, 0.18 mmol) and stirred
for 3 h at room temperature. A change of color from yellow to
red occurred. The solvent was evaporated in vacuo, and the
residue was washed three times with pentane (5 mL each) and
recrystallized from toluene/pentane (1:3). After the solution
was stored at -78 °C, orange-red, moderately air-stable
crystals precipitated, which were separated from the mother
liquor, washed twice with small amounts of pentane, and
1935, ν(N2C) 1920 (br) cm-1 1H NMR (200 MHz, C6D6): δ
.
7.42-6.90 (br m, 10 H, C6H5), 3.02 (d, J (Rh,H) ) 2.0 Hz, 1 H,
tCH), 2.43 (m, 6 H, PCHCH3), 1.29 (dvt, N ) 13.3, J (H,H) )
7.1 Hz, 36 H, PCHCH3). 13C NMR (50.3 MHz, C6D6): δ 129.9,
129.0, 124.9, 124.4 (all s, C6H5), 113.8 (dt, J (Rh,C) ) 15.3,
J (P,C) ) 3.2 Hz, CtCH), 109.2 (dt, J (Rh,C) ) 51.3, J (P,C) )
20.8 Hz, CtCH), 75.5 (br s, N2C), 24.9 (vt, N ) 18.5 Hz,
PCHCH3), 20.5 (s, PCHCH3). 31P NMR (81.0 MHz, C6D6): δ
46.4 (d, J (Rh,P) ) 132.2 Hz).
P r ep a r a t ion of tr a n s-[R h (CtCH)(N2CC12H8)(P iP r 3)2]
(25). A solution of 23 (86 mg, 0.18 mmol) in pentane (8 mL)
was treated at -30 °C with a solution of C12H8CN2 (35 mg,
0.18 mmol) in pentane (4 mL). The solution was slowly warmed
to room temperature, which led to a change of color from
orange-red to olive green. After the solution was stirred at ca.
20 °C for 5 min, the solvent was evaporated in vacuo and the
residue recrystallized from acetone (5 mL) at -30 °C. Olive
green moderately air-sensitive crystals were formed, which
were separated from the mother liquor, washed twice with
small amounts of acetone (0 °C), and dried: yield 91 mg (79%);
mp 89 °C. Anal. Calcd for C33H51N2P2Rh: C, 61.87; H, 8.03;
N, 4.37. Found: C, 61.74; H, 8.23; N, 3.91. IR (KBr): ν(tCH)
3240, ν(CtC) 1935, ν(N2C) 1920 (br) cm-1. 1H NMR (200 MHz,
C6D6): δ 7.86 (br d, J (H,H) ) 7.9 Hz, 2 H, H1 and H8), 7.66 (br
d, J (H,H) ) 7.9 Hz, 2 H, H4 and H5), 7.32, 7.10 (both ddd,
J (H,H) ) 7.8, 7.5 and 1.1 Hz, 2 H each, H2, H7 and H3, H6),
3.12 (dt, J (Rh,H) ) 2.0, J (P,H) ) 1.8 Hz, CtCH), 2.41 (m, 6
H, PCHCH3), 1.25 (dvt, N ) 13.5, J (H,H) ) 7.1 Hz, 36 H,
PCHCH3); the protons are numbered clockwise beginning at
the ortho position next to the five-membered ring. 13C NMR
(50.3 MHz, C6D6): δ 131.5, 130.5, 125.7, 122.7, 121.1, 118.6
(all s, C6H4), 116.3 (dt, J (Rh,C) ) 14.3, J (P,C) ) 3.7 Hz,
CtCH), 71.2 (br s, N2C), 24.9 (vt, N ) 18.5 Hz, PCHCH3), 20.3
(s, PCHCH3); signal for CtCH probably covered by signal of
solvent. 31P NMR (81.0 MHz, C6D6): δ 48.1 (d, J (Rh,P) ) 129.3
Hz).
dried: yield 92 mg (73%); mp 94 °C dec. Anal. Calcd for C32H52
ClN2OP2Rh: C, 56.42; H, 7.71; N, 4.11. Found: C, 56.14; H,
7.96; N, 3.78. IR (KBr): ν(N2C) 1935 (br), ν(CdO) 1610 cm-1
-
.
1H NMR (90 MHz, CDCl3): δ 7.17, 7.07 (both m, 5 H each,
C6H5), 2.62 (m, 6 H, PCHCH3), 1.30, 1.26 (both dvt, N ) 13.2,
J (H,H) ) 7.2 Hz, 18 H each, PCHCH3). 13C NMR (50.3 MHz,
C6D6): δ 150.9 (s, CdO), 139.3, 138.6 (both s, ipso-C of C6H5),
130.2, 129.3, 128.6, 128.3, 127.2, 125.4 (all s, C6H5), 101.2 (br
s, N2C), 23.2 (vt, N ) 17.2 Hz, PCHCH3), 19.6, 19.5 (both s,
PCHCH3). 31P NMR (81.0 MHz, C6D6): δ 31.1 (d, J (Rh,P) )
112.8 Hz).
P r epar ation of [Rh Cl{K2-N,O-N2C(P h )C(O)Me)}(P iP r 3)2]
(30). This compound was prepared as described for 29 from 2
(90 mg, 0.18 mmol) and CH3C(O)C(Ph)N2 (29 mg, 0.18 mmol)
in toluene (5 mL): orange-red, moderately air-stable solid;
yield 74 mg (65%); mp 108 °C dec. Anal. Calcd for C27H50ClN2-
OP2Rh: C, 52.39; H, 8.14; N, 4.53. Found: C, 51.90; H, 8.23;
N, 4.11. IR (KBr): ν(N2C) 1933 (br), ν(CdO) 1686 cm-1 1H
.
NMR (90 MHz, C6D6): δ 7.59-7.18 (br m, 5 H, C6H5), 2.63
(m, 6 H, PCHCH3), 2.00 (s, 3 H, C(O)CH3), 1.41, 1.30 (both
dvt, N ) 13.1, J (H,H) ) 7.1 Hz, 18 H each, PCHCH3). 13C NMR
(50.3 MHz, C6D6): δ 151.7 (s, CdO), 139.3 (s, ipso-C of C6H5),
130.0, 129.6, 129.3, 128.8, 125.8 (all s, C6H5), 100.3 (br s, N2C),
23.5 (vt, N ) 17.8 Hz, PCHCH3), 20.9 (s, C(O)CH3), 19.5, 19.2
(both s, PCHCH3). 31P NMR (81.0 MHz, C6D6): δ 31.0 (d,
J (Rh,P) ) 114.3 Hz).
P r ep a r a tion of tr a n s-[Rh (CtCtBu )(N2CP h 2)(P iP r 3)2]
(27). This compound was prepared as described for 24 from
26 (102 mg, 0.19 mmol) and Ph2CN2 (37 mg, 0.19 mmol) in
pentane (8 mL). After recrystallization from pentane at -78
°C green, slightly air-sensitive crystals were obtained: yield
127 mg (95%); mp 94 °C dec. Anal. Calcd for C37H61N2P2Rh:
C, 63.60; H, 8.80; N, 4.04. Found: C, 63.37; H, 8.96; N, 3.64.
P r ep a r a t ion of [R h Cl{N2C(CO2Me)C(O)CH 2CH 2CH -
(CH3)2}(P iP r 3)2] (31a ,b). A solution of 2 (100 mg, 0.20 mmol)
in toluene (10 mL) was cooled to -78 °C and then treated with
the diazo derivative of the keto ester (CH3)2CHCH2CH2C-
(O)C(CO2Me)N2 (40 mg, 0.20 mmol). A change of color from

3576 Organometallics, Vol. 22, No. 17, 2003
Ta ble 1. Cr ysta llogr a p h ic Da ta for Com p ou n d s 15, 20, a n d 31a
Werner et al.
15
20
31a
formula
Mr
C32H50ClN2OP2Rh
679.04
C23H42Cl5N2RhSb2
870.25
C27H56ClN2O3P2Rh
657.04
cryst size, mm
cryst syst
0.2 × 0.2 × 0.2
0.70 × 0.45 × 0.20
0.75 × 0.38 × 0.32
triclinic
monoclinic
triclinic
space group
a, Å
P1h (No. 2)
10.820(2)
P21/c (No. 14)
16.205(6)
P1h (No. 2)
11.2842(5)
b, Å
c, Å
11.8560(10)
14.419(2)
14.517(3)
14.779(6)
18.0279(8)
19.2465(9)
R, deg
70.810(10)
82.920(10)
72.370(10)
1664.3(4)
90
117.278(4)
97.328(4)
96.510(4)
3385.3(3)
â, deg
101.24(2)
90
3410(2)
γ, deg
V, Å3
Z
2
4
2
dcalcd, g cm-3
1.355
1.695
1.289
T, K
293(2)
0.716
ω/θ
43.96
293(2)
2.451
ω/θ
46
293(2)
0.699
ω/θ
46
µ, mm-1
scan method
2θ(max), deg
total no. of rflns
no. of unique rflns
no. of obsd rflns (I > 2σ(I))
no. of rflns used for refinement
no. of params refined
final R indices (I > 2σ(I))
R indices (all data)
resid electron density, e Å-3
4073
4483
9928
4072 (R(int) ) 0.0000)
3188
4028 (R(int) ) 0.0090)
3527
9367 (R(int) ) 0.0142)
8003
4072
364
4028
311
9367
679
R1 ) 0.0308, wR2 ) 0.0939a
R1 ) 0.0597, wR2 ) 0.1295a
0.452/-0.469
R1 ) 0.0336, wR2 ) 0.0838a
R1 ) 0.0395, wR2 ) 0.0892a
1.285/-0.613
R1 ) 0.0453, wR2 ) 0.1182a
R1 ) 0.0534, wR2 ) 0.1291a
1.032/-0.656
a
2
2
2
w-1 ) [σ2Fo + (0.0866P)2 + 0.0000P] (15), w-1 ) [σ2Fo + (0.0406P)2 + 11.0144P] (20), w-1 ) [σ2Fo + (0.0671P)2 + 5.2986P] (31a ),
where P ) (Fo2+2Fc2)/3.
yellow to dark red occurred. After the cooling bath was
removed, the solution was stirred for 1 h. The solvent was
evaporated in vacuo, and the oily residue was dissolved in
pentane (8 mL). The solution was stored at -78 °C for 12 h,
which led to the precipitation of red crystals. They were
separated from the mother liquor, washed three times with
small amounts of pentane (-30 °C), and dried: yield 113 mg
(84%). Anal. Calcd for C27H56ClN2O3P2Rh: C, 49.35; H, 8.59;
N, 4.26. Found: C, 49.46; H, 8.85; N, 4.20. IR (KBr): ν(N2C)
to separate these compounds by fractional crystallization
failed, the attempted separation by column chromatography
led mainly to decomposition. Data for 32 are as follows. 1H
NMR (200 MHz, C6D6): δ 7.05 (m, 5 H, C6H5), 6.59 (s, 1 H,
N2CH), 3.10 (s, 2 H, CH2), 2.31 (m, 6 H, PCHCH3), 1.20 (m, 36
H, PCHCH3). 31P NMR (81.0 MHz, C6D6): δ 31.1 (d, J (Rh,P)
) 114.2 Hz).
X-r a y Str u ctu r e Deter m in a tion of Com p ou n d s 15, 20,
a n d 31a . Single crystals of 15 were grown from toluene/hexane
at room temperature, those of 20 from acetone at -30 °C, and
those of 31a from pentane at -20 °C. The data were collected
on an Enraf-Nonius CAD4 diffractometer using monochro-
mated Mo KR radiation (λ ) 0.710 73 Å). Crystal data
collection parameters are summarized in Table 1. Intensity
data were corrected by Lorentz and polarization effects, and
empirical absorption corrections were applied (Ψ scan method,
minimum transmission 93.00% for 15, 56.28% for 20, and
93.19% for 31a ). The structures were solved by direct methods
(SHELXS-86).29 Atomic coordinates and anisotropic displace-
ment parameters were refined by full-matrix least squares
1
1950, 1900 (br), ν(CO2Me) 1701, ν(CdO) 1653, 1634 cm-1. H
NMR (200 MHz, C6D5CD3, 291 K): δ 3.60, 3.47 (both s, OCH3),
3.17 (m, C(O)CH2), 2.35 (m, PCHCH3), 1.60 (m, (CH3)2CHCH2),
1.22, 1.05 (both m, PCHCH3), 0.95, 0.88 (both d, J (H,H) ) 7.2
1
Hz, CH(CH3)2). H NMR (200 MHz, C6D5CD3, 223 K): δ 3.54
(br s, OCH3), 3.17 (m, C(O)CH2), 2.19 (m, PCHCH3), 1.56 (m,
(CH3)2CHCH2), 1.06, 0.91 (both br m, PCHCH3 and CH(CH3)2).
1H NMR (200 MHz, C6D5CD3, 253 K): δ 3.53, 3.40 (both s,
OCH3), 3.11 (m, C(O)CH2), 2.25 (m, PCHCH3), 1.55 (m,
(CH3)2CHCH2), 1.09, 0.94 (both m, PCHCH3), 0.91, 0.81 (both
1
d, J (H,H) ) 7.3 Hz, CH(CH3)2). H NMR (200 MHz, C6D5CD3,
against Fo (SHELXL-93).30 The asymmetric unit of 31a
2
313 K): δ 3.65, 3.54 (both s, OCH3), 3.14 (m, C(O)CH2), 2.44
(m, PCHCH3), 1.67 (m, (CH3)2CHCH2), 1.33, 1.14 (both m,
PCHCH3), 0.94 (br d, CH(CH3)2). 1H NMR (200 MHz, C6D5-
CD3, 333 K): δ 3.56 (br s, OCH3), 3.11 (m, C(O)CH2), 2.46 (m,
PCHCH3), 1.67 (m, (CH3)2CHCH2), 1.31 (br m, PCHCH3), 0.95
(br d, CH(CH3)2). 31P NMR (81.0 MHz, C6D5CD3, 291 K): δ
contains two independent molecules, which differs both in the
conformation of one isopropyl group and in the conformation
of the phosphines.
Ack n ow led gm en t . We thank the Deutsche For-
schungsgemeinschaft (Grant SFB 347), the Fonds der
Chemischen Industrie, and the Direccio´n de Investiga-
cio´n Cient´ıfica y Te´cnica (DGICYT) for financial support.
Moreover, we gratefully acknowledge support by Dr. J .
Perez-Prieto and Dr. S. Stiriba (synthesis of diazoke-
tones and diazoketoesters), Mrs. R. Schedl and Mr. C.
P. Kneis (elemental analysis and DTA), Mrs. M.-L.
Scha¨fer and Dr. W. Buchner (NMR measurements), and
Dr. G. Lange and Mr. F. Dadrich (mass spectra).
43.1 (d, J (Rh,P) ) 113.4 Hz), 31.6 (d, J (Rh,P) ) 111.9 Hz). 31
P
NMR (81.0 MHz, C6D5CD3, 223 K): δ 42.3 (d, J (Rh,P) ) 114.5
Hz), 30.7 (d, J (Rh,P) ) 112.6 Hz). 31P NMR (81.0 MHz, C6D5-
CD3, 333 K): δ 43.8 (d, J (Rh,P) ) 111.8 Hz), 32.3 (d, J (Rh,P)
) 110.5 Hz).
Rea ction of Com p ou n d 2 w ith P h CH 2C(O)CHN2. A
solution of 2 (90 mg, 0.18 mmol) in toluene (8 mL) was treated
at -78 °C with a solution of PhCH2C(O)CHN2 (29 mg, 0.18
mmol) in toluene (2 mL). After the cooling bath was removed,
the solution was stirred for 1 h. The solvent was evaporated
in vacuo, and the oily residue was dissolved in C6D5CD3 (0.5
1
mL). The H and 31P NMR spectra revealed that, in addition
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data and refinement parameters, bond lengths and angles, and
positional and thermal parameters for 15, 20, and 31a . This
material is available free of charge via the Internet at
http://pubs.acs.org.
to traces of unidentified byproducts, the compounds 32 and
12 were formed in the approximate ratio of 2:1. While attempts
(29) Sheldrick, G. M. Acta Crystallogr., Sect. A 1990, 46, 467-473.
(30) Sheldrick, G. M. SHELXL-93; University of Go¨ttingen, Go¨ttin-
gen, Germany, 1993.
OM0302037