Pentacoordinated diolefinic rhodium(I) organocomplexes with α-diimine ligands. Crystal structures of [Rh(Nbd)(LL)(PPh3)]ClO4 (Nbd=norbornadiene; LL=Bdh, biacetylidihydrazone; Pvdh, pyruvaldihydrazone; Bda, biacetyldianil)

Article abstract of DOI:10.1016/S0022-328X(00)00090-5

Pentacoordinated [Rh(Nbd)(LL)(PPh₃)]ClO₄ (Nbd=norbornadiene; LL=biacetyldihydrazone (Bdh) (1), pyruvaldehydedihydrazone (Pvdh) (2), glyoxaldihydrazone (Gdh) (3), biacetyldianyl (Bda) (4)) complexes are studied. The molecular structures of 1, 2, and 4 have been determined by X-ray diffraction. The three cations are best described as having distorted trigonal bipyramidal geometry with the olefinic bonds of Nbd spanning axial-equatorial sites; in 1 and 2 the other equatorial positions are occupied by the diimine groups and the PPh₃ is in axial position while in 4 the diimine occupies axial-equatorial sites and the PPh₃ is in equatorial position. Complexes 1 and 2 show intermolecular hydrogen bond N-HOClO₃ linkages, strong in 2. In acetone solution compounds 1-4 undergo phosphine dissociation, inhibited at 273 K; 2, 3 and 4 behave as dimers with bridging diimine ligands. Neutral pentacoordinated [Rh(X)(L₂)(LL)] (X=Cl, SnCl₃; L₂=Nbd, 1,5-cyclooctadiene (Cod); LL=Pvdh, Gdh) compounds undergo ionic dissociation in solution where at 183 K [Rh(SnCl₃)(Nbd)(Pvdh)] shows a square pyramidal structure with SnCl₃ in apical position.

Full text of DOI:10.1016/S0022-328X(00)00090-5

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 601 (2000) 311–319
Pentacoordinated diolefinic rhodium(I) organocomplexes with
a-diimine ligands. Crystal structures of [Rh(Nbd)(LL)(PPh3)]ClO4
(Nbd=norbornadiene; LL=Bdh, biacetylidihydrazone; Pvdh,
pyruvaldihydrazone; Bda, biacetyldianil)
Mohammed Bikrani a, Rachad El Mail a, Mar´ıa A. Garralda* a,1, Lourdes Ibarlucea a,
Elena Pinilla* b,2, M. Rosario Torres b
a Facultad de Qu´ımica de San Sebastia´n, Uni6ersidad del Pa´ıs Vasco, Apdo. 1072, E-20080 San Sebastia´n, Spain
b Departamento de Qu´ımica Inorga´nica, Laboratorio de Difraccio´n de Rayos X, Facultad de Ciencias Qu´ımicas, Uni6ersidad Complutense,
E-28040 Madrid, Spain
Received 3 November 1999; accepted 7 February 2000
Abstract
Pentacoordinated [Rh(Nbd)(LL)(PPh3)]ClO4 (Nbd=norbornadiene; LL=biacetyldihydrazone (Bdh) (1), pyruvaldehydedihy-
drazone (Pvdh) (2), glyoxaldihydrazone (Gdh) (3), biacetyldianyl (Bda) (4)) complexes are studied. The molecular structures of 1,
2, and 4 have been determined by X-ray diffraction. The three cations are best described as having distorted trigonal bipyramidal
geometry with the olefinic bonds of Nbd spanning axial–equatorial sites; in 1 and 2 the other equatorial positions are occupied
by the diimine groups and the PPh3 is in axial position while in 4 the diimine occupies axial–equatorial sites and the PPh3 is in
equatorial position. Complexes 1 and 2 show intermolecular hydrogen bond NꢀH···OClO3 linkages, strong in 2. In acetone
solution compounds 1–4 undergo phosphine dissociation, inhibited at 273 K; 2, 3 and 4 behave as dimers with bridging diimine
ligands. Neutral pentacoordinated [Rh(X)(L2)(LL)] (X=Cl, SnCl3; L2=Nbd, 1,5-cyclooctadiene (Cod); LL=Pvdh, Gdh)
compounds undergo ionic dissociation in solution where at 183 K [Rh(SnCl3)(Nbd)(Pvdh)] shows a square pyramidal structure
with SnCl3 in apical position. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Rhodium complexes; Pentacoordinated complexes; Diimine complexes; Crystal structures; Trichlorostannate
1. Introduction
the N-donor ligands occupy equatorial sites. It is well
known that in d8 metal complexes adopting a tbp
geometry s-donor ligands prefer axial sites, while the
strongest p-acceptor ligands lie in equatorial positions
where the largest extent of p-back-donation is expected
[15]. a-Diimines behave as s-donor and p-acceptor
ligands [16], therefore occupancy of equatorial–equato-
rial or axial–equatorial sites in a tbp can be expected.
Biacetyl derivatives show a lower p-acceptor capability
than glyoxal derivatives [17] and may also show repul-
sive interaction between the methyl groups when adopt-
ing the cis-chelating coordination [18]. Provided the
other ligands are the same, the disposition adopted for
a particular a-diimine should depend on its relative
s-donor/p-acceptor capability but also on steric re-
quirements [19], therefore we thought it interesting to
Five-coordinated compounds may adopt trigonal
bipyramidal (tbp) or square pyramidal (sp) geometry
and both types of structures are well known for penta-
coordinated rhodium(I) complexes [1–9]. Recently the
crystal structures of pentacoordinated [Rh(Cl)(Nbd)-
(py-2-CHꢁNR)] [10] and [Rh(Nbd)(RNꢁC(H)C(H)ꢁ
NꢀR)(PPh3)]BF4 (R=4-Me2NꢀC6H4, (Gaa)) [11] have
been reported and both compounds show a tbp struc-
ture where the diolefin occupies the usual equatorial–
axial disposition because of chelate strain [5,12–14] and
1 *Corresponding author.
2 *Corresponding author.
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00090-5

312
M. Bikrani et al. / Journal of Organometallic Chemistry 601 (2000) 311–319
study [Rh(Nbd)(LL)(PPh3)]ClO4 complexes contain-
ing diimines (LL) with different electronic and steric
properties. The ligands used were dihydrazones
H2NꢀNꢁC(R%)ꢀC(R¦)ꢁNꢀNH2 derived from glyoxal
(R%ꢁR¦ꢁH; Gdh), pyruvaldehyde (R%ꢁCH3, R¦ꢁH;
Pvdh) or biacetyl (R%ꢁR¦ꢁCH3; Bdh) and the biacetyl
derivative (C6H5)NꢁC(CH3)C(CH3)CꢁN(C6H5) (Bda).
Dihydrazones show, according to the absorptions in the
electronic spectra of Mo(CO)4(diimine) complexes, en-
hanced donor properties due to the presence of the
NH2 group [20] and low steric requirements. Bda, being
an aryl N-substituted diimine, shows enhanced p-accep-
tor capability [17] and higher steric requirements. On
the other hand neutral pentacoordinated complexes
[Rh(X)(Nbd)(LL)] with LL=2,2%-bipyridine (X=Cl)
[2] or glyoxalbis(cyclohexylimine) (X=SnCl3) [21]
adopt distorted sp geometry with the anionic group in
apical position, therefore neutral pentacoordinated
diolefinic compounds containing Gdh or Pvdh have
also been studied.
[{Rh(Nbd)Cl}2] with triphenylphosphine and AgClO4
in acetone solution (Rh–PPh3–ClO4=1:1:1) followed
by the addition of the corresponding a-diimine, (Rh–
LL=1:1). IR spectra of 1–4 show the expected bands
for coordinated diimine ligands and in the complexes
containing dihydrazones (1–3) the absorptions due to
w(NꢀH) are not displaced towards lower frequencies
with respect to the free ligands, though the appearance
of several bands in this region [22] and the splitting of
w(ClꢀO) in 2 and 3 suggest the existence of hydrogen
bonding between the amino groups and the ClO4 anion.
The molecular structures of compounds 1, 2 and 4
are shown in Figs. 1–3, respectively. Complex 1 crys-
tallises as [Rh(Nbd)(Bdh)(PPh3)]ClO4·1/2CH2Cl2. Crys-
tal data are collected in Table 1. Single crystals of
compound 3 could not be obtained due to decomposi-
tion. The crystals consist of [Rh(Nbd)(LL)(PPh3)]+
cations and ClO−4 anions in all cases. In both 1 and 2
anions and cations are bonded through hydrogen bonds
(Table 2). The molecular geometry in the three cases
can be best described as a distorted tbp, as can be
deduced from a careful study of the selected bond
distances and angles, which are given in Table 3. In
dihydrazone compounds 1 and 2, the disposition of the
ligands around the rhodium atom is analogous to that
found in the related [Rh(Nbd)(Gaa)(PPh3)]+ [11]. The
equatorial plane is occupied by both imino N atoms of
the LL ligand and one of the olefinic bonds C1122 of
the Nbd group, the other olefinic bond C4455 and the
P atom of the PPh3 ligand being in axial positions.
C1122 and C4455 are the midpoints of the olefinic
bonds in the Nbd group. In both compounds the
2. Results and discussion
Cationic pentacoordinated [Rh(Nbd)(LL)(PPh3)]-
ClO4 (LL=Bdh, 1; Pvdh, 2; Gdh, 3 or Bda, 4) com-
plexes are readily obtained by the reaction of
,
,
rhodium atom deviates 0.144(1) A for 1 and 0.132(1) A
for 2 from the N2N3C1122 plane [23]. This equatorial
plane forms a dihedral angle of 86.9(7) and 88.2(5)°
with the C4455RhP plane, and of 54.1(3) and 53.8(4)°
with the plane containing the diolefinic carbon atoms of
the Nbd group, C1C2C4C5, in 1 and 2 respectively.
These facts together with the shorter RhꢀC1122 dis-
tance with respect to the RhꢀC4455 distance, due to
stronger p-back-bonding in the equatorial plane [10,15],
confirm the distorted tbp geometry. The C8ꢀC9 dis-
,
tance in the diimine ligand is longer for 1 (1.46(2) A)
,
than for 2 (1.40(2) A), and this difference can be due to
the repulsive interaction between the two methyl groups
bonded to the carbon atoms of the diimine in 1 [18].
Also, in compound 2 the two RhꢀN distances are equal
,
(2.20(1) A) whilst in 1 they are different (2.224(4) and
,
2.168(7) A). In 2 only the amino group bonded to the
NꢁCH group is involved and forms two hydrogen
bonds, a strong bond with one oxygen atom of the
perchlorate group in the same asymmetric unit,
N4ꢀH4A···O1, and a weak bond with another perchlo-
rate group, N4ꢀH4B···O3% [22]. This feature leads to the
formation of ‘dimer units’ as depicted in Fig. 4. In 1 the
two amino groups have a weak hydrogen bond each
Fig. 1. PLUTO view of 1 showing the atomic numbering. The solvent
molecule and the hydrogen atoms have been omitted for clarity.

M. Bikrani et al. / Journal of Organometallic Chemistry 601 (2000) 311–319
313
Fig. 2. PLUTO view of 2 showing the atomic numbering. The hydrogen atoms have been omitted for clarity.
with the perchlorate group forming chains along the
x-axis.
RhN2C9C8N1 plane. These features may be due to the
repulsive interaction between the two methyl groups
and the two phenyl rings. Steric hindrance due to the
As shown in Fig. 3, compound 4 also shows a
distorted tbp geometry for the cation (Table 3) but now
the diimine occupies axial–equatorial sites, so that the
equatorial plane is occupied by one atom of the LL
ligand N2, one of the olefinic bonds C1122 of the Nbd
group and the P atom of the PPh3 ligand. The other
olefinic bond C4455 and the other N1 atom of the
diimine are in axial positions. In this case, the rhodium
atom is practically included in the P1N2C11122 plane.
This plane forms an angle of 58.9(3)° with the plane
containing the diolefinic carbon atoms of the Nbd
,
ligand. The RhꢀN1 axial distance, 2.053(8) A, is slightly
longer than that found in [Rh(Cod)(DAP)]+, 2.027(8)
,
A, containing an axial pyridine ligand trans to an
olefinic bond in a tbp geometry [24]. This RhꢀN1
distance is shorter than the RhꢀN2 equatorial distance,
,
2.225(8) A, suggesting good s-donor properties of the
bda ligand. Shorter axial than equatorial PtꢀN dis-
tances have also been observed in pentacoordinated
compounds containing 2,9-Me2-1,10-phenanthroline
,
[19]. Also the RhꢀP equatorial distance (2.398(3) A) in
complex 4 is longer than the RhꢀP axial distance in
compounds 1 and 2 (Table 3). The C8ꢀC9 distance
,
(1.48(1) A) is similar to the one found in 1 due to the
repulsion between the two methyl substituents in the
diimine ligand. Furthermore, the planar phenyl N-sub-
stituents are twisted 26.8(3)° from each other and
twisted 70.5(3) and 88.6(3)° respect to the
Fig. 3. PLUTO view of 4 showing the atomic numbering. The hydro-
gen atoms have been omitted for clarity.

314
M. Bikrani et al. / Journal of Organometallic Chemistry 601 (2000) 311–319
Table 1
Crystal and refinement data for [Rh(Nbd)(Bdh)(PPh3)]ClO4 (1), [Rh(Nbd)(Pvdh)(PPh3)]ClO4 (2) and [Rh(Nbd)(Bda)(PPh3)]ClO4 (4)
1
2
4
Empirical formula
Mr
C29H33ClN4O4PRh·1/2CH2Cl2
713.39
C
656.9
28H31ClN4O4PRh
C41H39ClN2O4PRh
793.07
Crystal system
Space group
Triclinic
Monoclinic
P21/c
14.472(2)
10.681(4)
18.585(3)
Monoclinic
P21/n
10.960(5)
18.960(4)
17.621(4)
(
P1
,
a (A)
11.0715(7)
,
b (A)
14.0915(8)
11.6597(6)
79.920(6)
71.398(5)
78.919(1)
1679.2(2)
2
,
c (A)
h (°)
i (°)
k (°)
103.56(1)
103.13(3)
3
,
V (A )
2792(1)
4
3566(1)
4
Z
F(000)
730
1.411
6.341
1344
1.56
8.06
1632
1.477
6.44
Dcalc. (g cm−3
)
v (mm−1
)
Scan technique
ꢀ/2q
ꢀ/2q
ꢀ/2q
Data collected
(0,−16,−12) to (11,16,13)
(−17,0,0) to (16,12,22)
(−13,0,0) to (12,22,20)
q range
2.22–66.6
5486
5486
4950
5486/352
0.077
1.43–24.98
4769
4618 (Rint=0.0665)
2175
4618/357
0.051
0.13
1.60–25.22
6475
6263 (Rint=0.106)
2939
6263/427
0.077
0.19
Reflections collected
Independent reflections
Observed reflections (I)]2|(I)
Data/parameters
a
R
b
Rw
F
0.22
a R=S[ꢀFoꢀ−ꢀFcꢀ]/SꢀFoꢀ.
b Rw =[S[w(Fo2−Fc2)]2/[S[w(Fo2)2]]1/2
.
F
In acetone solutions, measurements of the equivalent
conductivities of complexes 2–4 at 273 K at different
concentrations gave plots of the Onsager equation \e=
\o−Aꢁce for which A values agree with those calcu-
lated for 2:1 electrolytes [25], complex 1 shows
intermediate A values between those corresponding to
2:1 and 1:1 electrolytes, as shown in Table 5. This
suggests that the formation of binuclear cationic com-
plexes with bridging LL ligands in solution is less likely
for Bdh compared with Pvdh and Gdh, in keeping with
the lower tendency of biacetyl derivatives to behave as
bridges [26]. Bda in compound 4 also behaves as a
bridging ligand, likely due to the opening of the chelate
that allows the ligand to adopt the trans conformation
presence of these substituents in the diimine ligand, plus
the phenyl groups of PPh3 would favour the axial–
equatorial coordination of bda; the triphenylphosphine
ligand then occupies an equatorial site and the longer
RhꢀP distance alleviates steric repulsions. The occupa-
tion of axial–equatorial sites in complex 4 may be due
to a combination of electronic and steric factors since
the diimine in bda may be a better donor than the ones
in complexes 1 and 2.
NMR data of compounds 1 and 4 in CDCl3 are
collected in Table 4. According to 31P-NMR spectra, 1
and 4 undergo a phosphine dissociation equilibrium at
(4) or above (1) room temperature and show well-re-
solved doublets due to rhodium-coordinated phosphine,
1
in the range 273–213 K. Chemical shifts and J(Rh,P)
1
coupling constants are as expected [11]. Their H-NMR
Table 2
spectra confirm the diimine ligands being bonded
through the imino groups and both methyl groups
appear as a single resonance. The olefinic protons and
also the methinic protons of Nbd show only one reso-
nance each in the range 273–213 K, indicating dynamic
behaviour due to Berry pseudorotation [12] or to open-
ing of the chelate ring [21]; the alkene chemical shifts,
related to the geometry of norbornadiene pentacoordi-
nated compounds in solution [10], suggest a trigonal
bipyramidal geometry for these compounds also in
solution. Compounds 2 and 3 are insoluble in CDCl3.
,
Hydrogen bond geometry (A) and (°) for 1 and 2
NꢀH···O
d(NꢀH)
d(H···O)
d(N···O)
ÚNHO
1
N4ꢀH4B···O1
N1ꢀH1A···O2
1.00
0.86
2.65
2.54
3.04(2)
3.28(2)
103
146
a
2
N4ꢀH4A···O1
N4ꢀH4B···O3
1.23
0.83
1.89
2.42
3.12(1)
3.21(4)
174.4
160.0
b
a x+1, y, z.
b −x, −y+1, −z.

M. Bikrani et al. / Journal of Organometallic Chemistry 601 (2000) 311–319
315
range 273–213 K. Their 1H-NMR spectra show the
expected resonances for the diimine bonded ligands and
one resonance for the methinic protons of Nbd un-
modified down to 213 K (Table 4). The olefinic protons
of compounds 1, 3 and 4 show only one broad singlet
in the 273–213 K range, but in compound 2 (LL=
Pvdh) they show at 303 K one resonance at 3.53 ppm
that on lowering the temperature broadens and col-
lapses to give two resonances at 273 K. The signal at
higher field coincides with that of 1 (3.49 ppm) while
the signal at lower field coincides with that of 3 (3.55
ppm). This feature may be due to the existence in
solution of dimers, as shown by the conductivity data,
with diimine bridging ligand, so that the HꢀCꢁN frag-
ment is bonded to one of the rhodium atoms and the
CH3ꢀCꢁN fragment to the other rhodium atom.
Table 3
Selected bond lengths (A) and angles (°) for 1, 2 and 4
,
1
2
4
Bond lengths
RhꢀC(1)
RhꢀC(2)
RhꢀC(4)
RhꢀC(5)
RhꢀN(1)
RhꢀN(2)
RhꢀN(3)
RhꢀP
RhꢀC1122
RhꢀC4455
C(1)ꢀC(2)
C(4)ꢀC(5)
C(8)ꢀC(9)
2.102(9)
2.074(9)
2.208(9)
2.200(9)
2.08(1)
2.10(1)
2.16(1)
2.18(1)
2.10(1)
2.11(1)
2.20(1)
2.15(1)
2.053(8)
2.225(8)
2.168(7)
2.224(4)
2.313(2)
1.97(1)
2.10(1)
1.39(2)
1.34(2)
1.46(2)
2.20(1)
2.19(1)
2.332(3)
1.95(1)
2.04(1)
1.50(2)
1.47(2)
1.40(2)
2.398(3)
1.98(1)
2.07(1)
1.41(2)
1.35(2)
1.48(1)
Bond angles
Previously we have reported on neutral pentacoordi-
nated compounds containing Bdh [27]. We have now
studied neutral pentacoordinated compounds contain-
ing Pvdh and Gdh. [Rh(Cl)(diolefin)(LL)] (LL=Pvdh,
diolefin=Nbd, 5, Cod, 6; LL=Gdh, diolefin=Nbd, 7
Cod, 8) can be easily obtained by reacting [Rh(di-
olefin)Cl]2 with LL in dichloromethane. In their IR
spectra the w(CꢁN) vibrations, slightly modified upon
coordination, indicate bonding through both imino ni-
trogens and the weak w(RhꢀCl) confirm chlorine coor-
dination to the rhodium atom. w(NꢀH) are displaced
towards lower frequencies, as in analogous [Rh-
(Cl)(Cod)(Bdh)] [27], due to the intramolecular
NꢀH···ClꢀRh hydrogen bond [28]. The ability of chlo-
rine bonded to metal atoms to establish these interac-
tions has recently been reviewed [29]. These compounds
are only soluble in methanol where they undergo ex-
tended chloride dissociation (conductivity range for 1:1
electrolytes: 80–115 V−1 cm2 mol−1 [30]). Their high
insolubility precluded any NMR measurement.
C1122ꢀRhꢀP
C4455ꢀRhꢀP
96.7(3)
161.6(4)
69.6(4)
94.8(4)
162.2(5)
69.4(6)
137.5(4)
101.9(4)
68.2(5)
74.7(3)
C1122ꢀRhꢀC4455
N(1)ꢀRhꢀN(2)
N(2)ꢀRhꢀN(3)
N(1)ꢀRhꢀC1122
N(1)ꢀRhꢀC4455
N(2)ꢀRhꢀC1122
N(2)ꢀRhꢀC4455
N(3)ꢀRhꢀC1122
N(3)ꢀRhꢀC4455
N(1)ꢀRhꢀP
N(2)ꢀRhꢀP
N(3)ꢀRhꢀP
C(1)ꢀRhꢀC(2)
C(4)ꢀRhꢀC(5)
72.0(3)
72.7(3)
93.7(4)
160.8(4)
128.3(5)
110.9(4)
155.7(4)
97.3(3)
130.2(4)
104.7(4)
135.5(4)
103.1(5)
150.2(4)
98.2(5)
95.7(2)
94.2(2)
90.8(2)
93.5(2)
38.7(4)
35.3(4)
93.8(2)
91.9(2)
42.2(6)
39.5(6)
39.2(5)
36.0(4)
and alleviates steric strains in the cis conformation.
31P-NMR data of compounds 1–4 in acetone-d6 (Table
4) also show phosphine dissociation equilibrium at
room temperature and well-resolved doublets in the
Fig. 4. PLUTO of the ‘dimer units’ showing the hydrogen bonds for 2.

316
M. Bikrani et al. / Journal of Organometallic Chemistry 601 (2000) 311–319
Table 4
Selected NMR data for the [Rh(Nbd)(LL)(PPh3)]ClO4 complexes
Compound
Temperature (K)
LL
Nbd
31P-NMR
HꢀCꢁN
NH2
CH3
ꢁCH
CH
1 (LL=Bdh)
2 b (LL=Pvdh)
313 a
293 a
293 b
273 b
303
6.18
6.22
6.82
6.93
7.34; 6.67
7.43; 6.75
7.47; 6.77
7.30
1.63
1.58
1.72
1.73
1.68
1.68
1.67
3.39
3.32
3.47
3.49
3.67
3.64
3.62
3.65
3.59
3.59
3.57
3.56
3.55
3.37
3.39
3.48
3.50
34.37(s, br)
34.74(d, J=139)
31.68(s, br)
32.24(d, J=134)
29.75(s, br)
29.80(d, J=132)
29.72(d, J=134)
27.57(s, br)
27.11(d, J=132)
21.55(s, br)
22.18(d, J=129)
22.50(s, br)
7.10
7.09
7.08
7.12
7.11
3.53
283
273
303
273
3.52(br)
3.49; 3.55
3.56
3.55
3.06
3.04
3.07
3.04
3 b (LL=Gdh)
4 (LL=Bda)
7.41
293 a
273 a
293 b
273 b
2.10
2.09
2.18
2.17
23.33 (d, J=130)
a CDCl3.
b Acetone-d6.
When the above reaction is performed in the presence
of SnCl2, pentacoordinated trichlorostannate com-
pounds [Rh(SnCl3)(diolefin)(LL)] (LL=Pvdh, diole-
fin=Nbd, 9, Cod, 10; LL=Gdh, diolefin=Nbd, 11
Cod, 12) are obtained that show covalently bonded SnCl3
groups [31] along with diimino bonded ligands. In
acetone solution norbornadiene complexes behave al-
most as non-electrolytes while 1,5-cyclooctadiene com-
pounds undergo extended ionic dissociation. In methanol
solution compounds 9–12 behave as 1:1 electrolytes.
Reported [Rh(Cod)(Bdh)](SnCl3) is ionic [27]. 119Sn-
NMR spectra of Pvdh compounds 9 and 10 in acetone
solution show a broad singlet at ca. 170 ppm that
indicates tin dissociation at room temperature, most
likely via SnCl−3 dissociation on account of the conduc-
tivity data. Only for compound 9 has it been possible to
observe at 183 K a doublet due to SnCl3 coordinated to
rhodium and the values of chemical shift and coupling
constant are in agreement with analogous compounds
containing other diimines [21,27]. Accordingly with this,
in its 1H-NMR spectrum the olefinic and methinic
resonances are broad singlets at room temperature,
coalesce and resolve into two signals each at 183 K. The
low-temperature spectrum agrees with a square pyrami-
dal limiting structure with the SnCl−3 group occupying
the axial position similar to that found in related
[Rh(SnCl3)(Nbd)(glyoxalbis(cyclohexylimine))] [21]; the
chemical shift of the olefinic resonances of norbornadiene
in the lower field range also indicates this structure [10].
The 1H-NMR spectrum of 10 shows at room temperature
two resonances for the olefinic protons of cyclooctadiene,
most likely due to two different species in solution, i.e.
[Rh(SnCl3)(Cod)(Pvdh)] and [Rh(Cod)(Pvdh)]+. Gdh
complexes 11 and 12 are only soluble in CD3OD and
show the expected resonances for tetracoordinated com-
pounds.
3. Experimental
The preparation of the metal complexes was carried
out at room temperature (r.t.) under nitrogen by stan-
dard Schlenk techniques. [{M(L2)Cl}2] [32] were pre-
pared as previously reported. a-Diimines [18,33] were
synthesised according to known procedures.
Microanalysis were carried out with a Perkin–Elmer
240C microanalyser. Conductivities were measured in
acetone or methanol solution with a Metrohm E 518
conductimeter. IR spectra were recorded with a Nicolet
FTIR 740 spectrophotometer in the range 4000–50
cm−1 using KBr pellets or nujol mulls between
polyethylene sheets. NMR spectra were recorded with an
1
XL-300 Varian spectrometer, H (TMS internal stan-
dard) and 31P (H3PO4 external standard) spectra were
measured from CDCl3, acetone-d6 or CD3OD solutions,
119Sn (SnMe4 external standard) spectra were measured
from 1:1 acetone–acetone-d6 solutions. Mass spectra
were recorded on a VG Autospec, by liquid secondary
ion (LSI) MS using nitrobenzylalcohol as matrix and a
caesium gun (Universidad de Zaragoza).
Table 5
Conductivity data for [Rh(Nbd)(LL)(PPh3)]ClO4 complexes
a
a
b
b
Complex
\
Aexp
Atheor
(1:1)
Atheor
(2:1)
o
(V−1 cm2 eq−1
)
1 (LL=Bdh)
2 (LL=Pvdh)
3 (LL=Gdh)
4 (LL=Bda)
176
174
190
170
942
1284
1378
1427
687
691
713
676
1335
1340
1408
1447
a Measured in acetone solution. From the Onsager’s equation
\e=\o−Aꢁce plot.
b Calculated according to Ref. [25].

M. Bikrani et al. / Journal of Organometallic Chemistry 601 (2000) 311–319
317
3.1. Preparation of complexes
[Rh(Nbd)(LL)(PPh3)]ClO4
cm2 mol−1): 40 (MeOH). Anal. Calc. for
C10H16ClN4Rh: C, 36.33; H, 4.88; N, 16.95; Found: C,
36.17; H, 4.78; N, 16.70%.
To a CH2Cl2 solution of [{Rh(L2)Cl}2] (0.06 mmol)
and triphenylphosphine (0.12 mmol) was added an
acetone solution of the stoichiometric amount (0.12
mmol) of AgClO4. After 30 min the formed AgCl was
filtered. The obtained solution was evaporated to dry-
ness and the residue solved in dichloromethane. Addi-
tion of the required amount (0.12 mmol) of the
corresponding ligand to this solution followed by addi-
tion of diethyl ether gave precipitates that were filtered
off, washed with diethyl ether and vacuum dried.
Yields: 60–80%.
3.1.7. [RhCl(Cod)(P6dh)] (6)
IR (cm−1): 3315(m), 3256(m), 3174(s), 3088(s)
w(NꢀH); 1588(m) w(CꢁN); 278(w) w(RhꢀCl). \M (V−1
cm2 mol−1): 53 (MeOH). Anal. Calc. for
C11H20ClN4Rh: C, 38.11; H, 5.82; N, 16.16; Found: C,
37.96; H, 5.76; N, 15.61%.
3.1.8. [RhCl(Nbd)(Gdh)] (7)
IR (cm−1): 3302(s), 3281(s), 3112(s), 3091(s) w(NꢀH);
1578(s) w(CꢁN); 288(w) w(RhꢀCl). \M (V−1 cm2
mol−1): 59 (MeOH). Anal. Calc. for C9H14ClN4Rh: C,
34.14; H, 4.46; N, 17.70; Found: C, 34.08; H, 3.86; N,
17.64%.
3.1.1. [Rh(Nbd)(Bdh)(PPh3)]ClO4 (1)
IR (KBr, cm−1): 3404(m), 3392(m), 3304(m),
w(NꢀH); 1607(m), w(CꢁN); 1098(vs), w(ClꢀO). FAB
MS: Calc. for C29H33N4P103Rh: 571; observed: 571
[M+]. Anal. Calc. for C29H33ClN4O4PRh·0.5CH2Cl2: C,
49.67; H, 4.80; N, 7.85; Found: C, 49.19 H, 4.99; N,
7.54%.
3.1.9. [RhCl(Cod)(Gdh)] (8)
IR (cm−1): 3323(m), 3274(m), 3140(s), 3091(s)
w(NꢀH); 1573(s) w(CꢁN); 278(w) w(RhꢀCl). \M (V−1
cm2 mol−1): 57 (MeOH). Anal. Calc. for
C10H18ClN4Rh: C, 36.11; H, 5.45; N, 16.84; Found: C,
35.67; H, 5.14; N, 16.47%.
3.1.2. [Rh(Nbd)(P6dh)(PPh3)]ClO4 (2)
IR (KBr, cm−1): 3422(m), 3389(m), 3297(m),
3207(w), w(NꢀH); 1585(m), w(CꢁN); 1111(s), 1094(s),
w(ClꢀO). FAB MS: Calc. for C28H31N4P103Rh: 557;
observed: 557 [M+]. Anal. Calc. for C28H31ClN4-
O4PRh: C, 51.20; H, 4.76; N, 8.53; Found: C, 50.80 H,
4.71; N, 8.39%.
3.2. Preparation of trichlorostannato complexes
To a CH2Cl2 solution of [{Rh(L2)Cl}2] (0.06 mmol)
was added two equivalents (0.12 mmol) of the corre-
sponding ligand. Addition of a methanol solution of
SnCl2 (0.12 mmol) led to red solutions. Removal of
CH2Cl2 gave red solids that were filtered off, washed
with MeOH and vacuum dried. Yields: 60–90%.
3.1.3. [Rh(Nbd)(Gdh)(PPh3)]ClO4 (3)
IR (KBr, cm−1): 3422(s), 3387(m), 3295(s), 3218(m),
3204(m) w(NꢀH); 1591(m), w(CꢁN); 1112(s), 1090(s),
w(ClꢀO). FAB MS: Calc. for C27H29N4P103Rh: 543;
observed: 543 [M+]. Anal. Calc. for C27H29ClN4-
O4PRh·0.5CH2Cl2: C, 49.28; H, 4.48; N, 8.44; Found:
C, 49.25 H, 4.52; N, 8.25%.
3.2.1. [Rh(SnCl3)(Nbd)(P6dh)] (9)
IR (cm−1): 3354(m), 3274(m), 3223(m), 3203(m)
w(NꢀH); 1584(m) w(CꢁN); 298(m), 258(m) w(SnꢀCl).
1
\
M
(V−1 cm2 mol−1): 15 (acetone), 90 (MeOH). H-
NMR (acetone-d6, 183 K): l 7.51 (s, HꢀCꢁN), 7.37 (s,
NH2), 6.73 (s, NH2), 2.08 (s, CH3), 4.07 (2H, ꢁCH and
3.1.4. [Rh(Nbd)(Bda)(PPh3)]ClO4 (4)
1
IR (KBr, cm−1): 1590(m), w(CꢁN); 1090(vs),
w(ClꢀO). FAB MS: Calc. for C41H39N2P103Rh: 693;
observed: 693 [M+]. Anal. Calc. for C41H39ClN2-
O4PRh: C, 62.09; H, 4.96; N, 3.53; Found: C, 61.66 H,
4.71; N, 3.42%.
1H, CH), 3.67 (2H, ꢁCH), 3.24 (1H, CH). H-NMR
(acetone-d6, 293 K): l 6.80 (s, NH2), 6.14 (s, NH2), 3.81
(4H, ꢁCH), 3.65 (2H, CH), the other resonances are the
same as those at 193 K. 119Sn-NMR (acetone-d6, 183
1
K): l 178 (d; J(Rh,Sn), 543Hz). 119Sn-NMR (acetone-
d6, 293 K):
l
177 (br). Anal. Calc. for
3.1.5. Preparation of complexes [RhCl(diolefin)(LL)]
To a CH2Cl2 solution of [{Rh(L2)Cl}2] (0.06 mmol)
was added two equivalents (0.12 mmol) of the corre-
sponding ligand upon which precipitation of red com-
plexes occurred that were filtered off, washed with
dichloromethane and vacuum dried. Yields: 60–80%.
C10H16Cl3N4RhSn: C, 23.09; H, 3.10; N, 10.77; Found:
C, 22.80; H, 3.03; N, 10.51%.
3.2.2. [Rh(SnCl3)(Cod)(P6dh)] (10)
IR (cm−1): 3352(m), 3279(m), 3268(m), 3221(m),
3191(m) w(NꢀH); 1584(m) w(CꢁN); 291(m), 265(m),
245(m) w(SnꢀCl). \M (V−1 cm2 mol−1): 67 (acetone),
1
3.1.6. [RhCl(Nbd)(P6dh)] (5)
75 (MeOH). H-NMR (acetone-d6): l 7.54 (s, HꢀCꢁN),
IR (cm−1): 3318(m), 3266(m), 3131(s), 3087(s)
w(NꢀH); 1589(m) w(CꢁN); 280(w) w(RhꢀCl). \M (V−1
6.85 (br, NH2), 6.65 (br, NH2), 6.16 (br, NH2), 2.12 (s,
CH3), 4.45 (br, ꢁCH), 4.27 (br, ꢁCH). 119Sn-NMR

318
M. Bikrani et al. / Journal of Organometallic Chemistry 601 (2000) 311–319
(acetone-d6): l 160 (br). Anal. Calc. for C11H20-
Cl3N4RhSn: C, 24.64; H, 3.76; N, 10.45; Found: C,
24.88 H, 3.74; N, 10.21%.
ses, including fixed positions. The largest residual peak
−3
,
for 1 in the final Fourier difference map was 2.3 e A
near the disordered solvent molecule and for 2 and 4,
0.9 and 1.9 e A−3, respectively, in the vicinity of the Rh
atom.
,
3.2.3. [Rh(SnCl3)(Nbd)(Gdh)] (11)
IR (cm−1): 3345(s), 3274(m), 3204(m) w(NꢀH);
1571(m) w(CꢁN); 339(m), 308(m) w(SnꢀCl). \M (V−1
cm2 mol−1): 18 (acetone), 90 (MeOH). 1H-NMR
(CD3OD): l 7.12 (s, HꢀCꢁN), 4.40 (br, ꢁCH), 3.97 (br,
CH). Anal. Calc. for C9H14Cl3N4RhSn: C, 21.36; H,
2.79; N, 11.07; Found: C, 21.78; H, 2.76; N, 10.93%.
4. Conclusions
Pentacoordinated [Rh(Nbd)(LL)(PPh3)]ClO4 (LL=
a-diimine) adopts distorted trigonal bipyramid geome-
try. Dihydrazones prefer the occupancy of equatorial
positions and a combination of electronic and steric
factors makes biacetyldianyl occupy axial–equatorial
sites. Dihydrazone compounds show intermolecular hy-
drogen bond N-H...OClO3 linkages, weaker in the bi-
acetyl derivative. In acetone solution Gdh, Pvdh and
Bda behave as bridging ligands. In solution
[Rh(SnCl3)(Nbd)(Pvdh)] prefers a square pyramidal
structure with SnCl3 in apical position at 183 K.
3.2.4. [Rh(SnCl3)(Cod)(Gdh)] (12)
IR (cm−1): 3373(s), 3267(s), 3197(m) w(NꢀH);
1565(m) w(CꢁN); 293(m), 263(m) w(SnꢀCl). \M (V−1
cm2 mol−1): 46 (acetone), 102 (MeOH). 1H-NMR
(CD3OD): l 7.17 (s, HꢀCꢁN), 4.75 (br, ꢁCH). Anal.
Calc. for C10H18Cl3N4RhSn; C, 23.00; H, 3.47; N,
10.73; Found: C, 23.24 H, 3.41; N, 10.74%.
3.3. Crystallography
Prismatic single crystals of 1, 2 (yellow) and 4 (red)
were grown by layering dichloromethane solutions with
diethyl ether. The data for 1 were collected up to
2q=134° with graphite-monochromated Cu–Ka radia-
5. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC no. 136303 for compound 1, no.
136304 for compound 2 and no. 136305 for compound
4. Copies of this information may be obtained free of
charge from The Director, CCDC, 12, Union Road,
Cambridge CB2 1EZ [Fax +44(1223)336-033] or
e-mail deposit@ccdc.cam.ac.uk or http://www.ccdc.
cam.ac.uk.
,
tion (u=1.5418 A) on a Seifert XRD 3000s non-con-
ventional four-cycle diffractometer using an ꢀ/2q scan
mode. For 2 and 4 the data were collected on an
Enraf–Nonius CAD4 diffractometer with graphite-
,
monochromated Mo–Ka radiation (u=0.71073 A) and
unit cell constants refined by least-squares fitting of the
q values of 25 reflections, with 2q range of 5–24° for 2
and 13–27° for 4. Three check reflections were moni-
tored after every 97 reflections for the three com-
pounds. No appreciable drop in the intensities of
standard reflections was observed for 1 and 2, while for
4 a decay of 10% was observed.
Acknowledgements
Partial financial support by CICYT (Project MAT96-
1629-E), UPV and Diputacio´n Foral de Guipuzcoa is
gratefully acknowledged.
In each case the heavy atoms have been located by
the Patterson method and the rest of the atoms by
Fourier syntheses. The refinement was done by full-ma-
trix least-squares on F2
(SHELXL97) [34] with the fol-
lowing differences: for 1 and 4 some non-resolvable
disorder from thermal motion has been found for the
oxygen atoms of the perchlorate group, and because of
this, these atoms were refined only isotropically. In
addition, for 1 solvent was found in the last cycles of
refinement with a very important non-resolvable posi-
tional disorder, which was included and their positions
fixed. The best R factor was obtained with 1/2CH2Cl2.
The rest of the non-hydrogen atoms were refined an-
isotropically. The hydrogen atoms were calculated and
refined as riding on a carbon-bonded atom with com-
mon isotropic displacement parameters, except for the
hydrogen atoms of the amino groups, which were
found as the first peaks in a Fourier difference synthe-
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