Ligand-behaviour-of-P-functionally-substituted-organotin-halides-Synthesis,-structure,-and-intramole
Journal of Organometallic Chemistry 572(1999)117–123
Ligand behaviour of P-functionally substituted organotin halides:synthesis,structure,and intramolecular oxidative addition of
[{Me 2(Cl)SnCH 2CH 2PPh 2}2Rh(CO)Cl]
Dirk Kruber,Kurt Merzweiler,Christoph Wagner,Horst Weichmann *
Institut fu ¨r Anorganische Chemie ,Martin -Luther -Uni 6ersita ¨t Halle -Wittenberg ,Kurt -Mothes -Stra?e 2,D -06120Halle (Saale ),Germany
Received 22July 1998
Abstract
The reaction of [Rh(CO)2Cl]2with Me 2(Cl)SnCH 2CH 2PPh 2yields the square-planar rhodium(I)complex [{Me 2(Cl)SnCH 2CH 2PPh 2}2Rh(CO)Cl](1).The crystal structure of 1is characterized by an intramolecular Rh–Cl···Sn and an intermolecular Sn–Cl···Sn interaction.The latter gives rise to the dimerization of 1under formation of a 16-membered macrocycle.In solution the complex is monomeric and undergoes a fast exchange between the intramolecular Rh–Cl···Sn contacts of the two ligands.By heating in toluene at 100°C,1transforms under elimination of methane and ethylene into the rhodium(III)complex [{Me(Cl)SnCH 2CH 2PPh 2}2Rh ?111111111o
(CO)Cl](2).Both in solid state and in solution 2shows a bicyclic structure with two Sn,P,and Rh containing ?ve-membered chelate rings with a |-Rh–Sn bond.?1999Elsevier Science S.A.All rights reserved.Keywords :Rhodium stannyl complexes;Oxidative addition of Sn–C bonds;Pentacoordination;Crystal structures
1.Introduction
-Diphenylphosphinoalkyl triorganostannanes R 3Sn(CH 2)n PPh 2(R =Me,Ph;n =2,3)[1–3]and the distannanes [Ph 2P(CH 2)n Me 2Sn–]2(n =2,3)[3]are suitable ligands to form phosphinoalkylstannyl chelate complexes with the structural element [M] PPh 2(CH 2)n Sn ?111111111o
R 2in ‘chelate assisted’oxidative additions of their Sn–C(R)–and Sn–Sn-bonds to Pd 0,Pt 0and Fe 0complex fragments [4–8].The reaction of Me 3SnCH 2CH 2PMe 2with [Rh(CO)2Cl]2and Cr(CO)6yields the complexes [{Me 3SnCH 2CH 2PMe 2}2-Rh(CO)Cl]and [(Me 3SnCH 2CH 2PMe 2)Cr(CO)5].In these compounds Me 3SnCH 2CH 2PMe 2acts as a monodentate ligand by P M coordination without any interaction between the tin and transition metal [2,9].
Recently,we started investigations of the ligand be-haviour of P-functionally substituted organotin halides Me 3?m (X)m Sn(CH 2)n PPh 2(X =Cl,m =1–3;n =2,3)and related compounds in transition metal complexes [10].In contrast to the compounds mentioned above in these ligand systems the tin atom is a centre of variable Lewis-acidity.This should have the following conse-quences:(i)in reactions of the ligands with transition metal complexes containing metal–halogen functions the formation of metal–halogen–tin bridges is expected.This should in?uence the structure and the reactivity of the resulting complexes;(ii)the formation of metallacy-cles by elimination of the organotin group of the ligands under formation of |-M–C bonds (e.g.M =Pd or Pt)can occur in case of a suitable length of the (CH 2)n –bridge in the ligands;(iii)?nally,in reactions of Me 3?m (X)m Sn(CH 2)n PPh 2(m =2,3)with electron-rich low-valent metal complexes the formation of compounds with M Sn-donor–acceptor interactions is possible which represent intermediates in oxidative additions of Sn–Hal bonds of the ligands to the metal centre [11].
*Corresponding author.Fax:+493455527028;e-mail:weich-mann@chemie.uni-halle.de 0022-328X /99/$-see front matter ?1999Elsevier Science S.A.All rights reserved.PII S0022-328X(98)00912-7
D.Kruber et al./Journal of Organometallic Chemistry572(1999)117–123 118
In this paper we report the synthesis,molecular
structure,and reactivity of the complex
[{Ph2PCH2CH2Sn(Cl)Me2}2Rh(CO)Cl].
2.Results and discussion
2.1.Synthesis
The reaction of Me2(Cl)SnCH2CH2PPh2[3]with
[Rh(CO)2Cl]2in a molar ratio of2:1in benzene at room
temperature yields the complex[{Me2(Cl)SnCH2CH2-
PPh2}2Rh(CO)Cl](1)(Eq.(1)).To avoid the formation
of dinuclear species solutions of the starting compo-
nents in benzene are dropped simultaneously in pure
benzene.
4Me2(Cl)SnCH2CH2PPh2+[Rh(CO)2Cl]2
C6H6?2CO 2[{Me2(Cl)SnCH2CH2PPh2}2Rh(CO)Cl]
1
(1)
During the reaction the equivalent amount of CO is evolved.Pure1could be obtained by recrystallization from CH2Cl2/hexane.The yellow crystals melt at124–126°C and are soluble in aromatic and chlorinated hydrocarbons.A strong absorption at1975cm?1in the CO valence region of the IR spectrum of1(in CsBr) indicates a square-planar ligand arrangement at the rhodium(I)centre[2,18].
2.2.Molecular structure of
[{Me2(Cl)SnCH2CH2PPh2}2Rh(CO)Cl](1)
The molecular structure of1along with the atom-numbering scheme are shown in Fig.1.Selected bond lengths and angles are listed in Table1.The molecular structure of1shows that the two Me2(Cl)SnCH2CH2PPh2ligands are both coordinated via the phosphorus atom to the rhodium atom.As a result of its Lewis acidity the tin atom of one ligand (Sn2)interacts with the chlorine atom at the rhodium centre to form a six-membered ring with an intramolec-ular Rh–Cl···Sn bridge.Simultaneously the same atom (Sn2)is linked with the Me2(Cl)Sn-group of a neigh-bouring complex molecule via an intermolecular Sn(2)–Cl(2)···Sn(1%)interaction with the consequence of formation of centrosymmetric dimers.The crystallo-graphically imposed inversion centre of the structure coincides with the midpoint of the sixteen membered macrocycle formed by the dimerization of1.No un-usual contacts between adjacent dimeric species are observed.
The rhodium atom exhibits a square-planar coordi-nation sphere with only slight distortion(P(1)–Rh–P(2)179.0(1)°,Cl(1)–Rh–C(33)176.3(2)°).The two phosphorus atoms are in the trans position.The Rh–Cl,Rh–P and Rh–C bond lengths are comparable with those in other complexes of the type trans-[RhCl(CO) (PPh2Alk)2],e.g.trans-[RhCl(CO)(PPh2Me)2][12]. The geometry around the two tin atoms is a distorted trigonal bipyramid.In both cases the equatorial plane is occupied by three carbon atoms,belonging to the methyl groups and the P-bonded ethylene group,and one of the axial positions is occupied by the chlorine atoms Cl(2)and Cl(3),respectively.The pentacoordina-tion is achieved in different ways:the second axial position at Sn(2)is occupied by the chlorine atom Cl(1) of the Rh–Cl function,whereas the coordination sphere around Sn(1)is completed by the chlorine atom Cl(2%)of the intermolecularly coordinated Me2(Cl)Sn-CH2CH2PPh2ligand of a neighbouring molecule. Comparing Sn(2)and Sn(1)the trigonal–bipyramidal skeleton of Sn(1)is distorted more towards a mono-capped tetrahedron because of the stronger intramolec-ular Sn(2)···Cl(1)coordination than the intermolecular Sn(1)···Cl(2%)interaction.This is indicated by the smaller difference between the sums of the three equa-torial and the three axial angles to the covalent bonded Cl ax at Sn(1)(DS(q)=52.9°)compared with Sn(2) (DS(u)=75.4°)[13,14],the greater deviation of Sn(1) Fig.1.Molecular structure of[{Me2(Cl)SnCH2CH2PPh2}2Rh(CO)Cl] (1)with atom-numbering.Hydrogen atoms are omitted for clarity.
D .Kruber et al ./Journal of Organometallic Chemistry 572(1999)117–123
119
Table 1
Selected bond lengths (A
?),angles (°)and endocyclic torsion angles (°)for [{Me 2(Cl)SnCH 2CH 2PPh 2}2Rh(CO)Cl](1)Bond lengths (A
?) 2.312(1)Sn(2)–C(5)Rh–P(1) 2.118(6)Sn(2)–C(6) 2.115(6)2.336(1)Rh–P(2) 2.363(2)Sn(2)–Cl(2) 2.467(2)Rh–Cl(1) 2.920(1)Sn(2)–Cl(1)Rh–C(33) 1.793(5)P(1)–C(1) 1.834(5)Sn(1)–C(4) 2.149(4)P(1)–C(9) 1.812(5)Sn(1)–C(7) 2.118(6)2.118(6)P(1)–C(15)Sn(1)–C(8) 1.815(4)2.405(2)P(2)–C(3)Sn(1)–Cl(3) 1.843(4)1.817(4)P(2)–C(21)Sn(1)–Cl(2’) 3.254(2) 1.815(4)Sn(2)–C(2)P(2)–C(27)2.143(5)Bond angles (°)Cl(2)–Sn(2)–C(2)90.7(2)P(1)–Rh–P(2)179.0(1)176.3(2)Cl(2)–Sn(2)–C(5)Cl(1)–Rh–C(33)96.7(2)95.5(2)88.8(1)P(1)–Rh–Cl(1)Cl(2)–Sn(2)–C(6)176.4(1)Cl(2)–Sn(2)–Cl(1)P(1)–Rh–C(33)88.8(2)92.1(1)Rh–P(1)–C(1)P(2)–Rh–Cl(1)118.2(2)Rh–P(1)–C(9)115.1(2)90.4(2)P(2)–Rh–C(33)114.4(2)Rh–P(1)–C(15)C(4)–Sn(1)–C(7)111.1(1)C(1)–P(1)–C(9)101.8(2)C(4)–Sn(1)–C(8)120.3(3)117.1(3)C(1)–P(1)–C(15)C(7)–Sn(1)–C(8)102.9(2)106.2(2)96.9(2)Cl(3)–Sn(1)–C(4)C(9)–P(1)–C(15)101.5(2)Rh–P(2)–C(3)114.0(2)Cl(3)–Sn(1)–C(7)Rh–P(2)–C(21)115.0(2)Cl(3)–Sn(1)–C(8)100.5(3)175.0(1)Rh–P(2)–C(27)Cl(3)–Sn(1)–Cl(2’)113.9(1)119.8(3)C(3)–P(2)–C(21)C(2)–Sn(2)–C(5)105.5(2)118.6(3)C(3)–P(2)–C(27)105.5(2)C(2)–Sn(2)–C(6)101.6(2)
C(21)–P(2)–C(27)
C(5)–Sn(2)–C(6)
119.9(4)
Torsion angles (°)67.5(2)C(2)–C(1)–P(1)–Rh 68.5(5)Rh–Cl(1)–Sn(2)–C(2)C(1)–P(1)–Rh–Cl(1)3.3(4)15.5(2)Cl(1)–Sn(2)–C(2)–C(1)P(1)–Rh–Cl(1)–Sn(2)?65.7(1)
Sn(2)–C(2)–C(1)–P(1)?74.3(5)
The torsion angles in Table 1indicate that the six-membered chelate rings in 1adopt a boat con-formation.The Rh,P(1),Sn(2)and C(2)atoms are nearly co-planar,and the ring is puckered at the C(1)and Cl(1)edge.
2.3.Structure of 1in solution
The results of 1H-,31P-and 119Sn-NMR spectro-scopic studies of 1in C 6D 6are summarized in Table 2.In solution 1is monomeric.This is proved by osmome-try in C 6H 6at 45°C (MW measured:966.5(Calc.961.4))and spectroscopic data.The NMR spectra re-veal only one 31P and 119Sn signal and in the 1H-NMR spectrum only one signal is shown for the methyl group protons at the tin atoms.That means,in solution neither an intermolecular Sn(1)···Cl(2%)nor an in-tramolecular Sn(2)···Cl(1)interaction exists.On the other hand,the high-?eld shift of the 119Sn-NMR signal (112.6ppm)and the increase of the 2J (1HC 119Sn)cou-pling constant (60.2Hz)compared with the ligand Me 2(Cl)SnCH 2CH 2PPh 2(l 119Sn =142ppm,2J (1HC 119Sn =57.8Hz [3])indicate for the tin atoms in 1at least weak hypervalent contacts.Obviously,1undergoes a dynamic process in solution by a fast intramolecular exchange between Rh–Cl(1)···Sn(1)and Rh–Cl(1)···Sn(2)interactions.From the unchanged 1H-NMR spectrum follows that even at ?70°C this process is fast within the NMR time scale.
As a consequence of the natural abundance of the 119
Sn isotope of 8.58%the dominant isotopomer of 1in solution contains only one 119Sn atom (the portion of the isotopomer with two 119Sn atoms is 0.74%).That means the 119Sn-NMR spectrum and the satellite part of the 31P-NMR spectrum of 1are parts of an AA %X spin system (A,A %=31P,X =119Sn)because the two phosphorus atoms are chemically but not magnetically https://www.sodocs.net/doc/1417480402.html,puter simulation gave the coupling constants 2J (31P,31P)=338.9and 3J (31P,119Sn)=203.2Hz.
2.4.Intramolecular oxidati 6e addition reaction of 1
Heating 1in toluene for 2days at 100°C the formerly yellow solution turns to orange and after evaporation to dryness the yellow rhodium(III)complex [{Me(Cl)SnCH 2CH 2PPh 2}2Rh ?111111111o
(CO)Cl](2)could be isolated (Eq.(2)).Recrystallization from CH 2Cl 2/hexane yields a pure product.
from the plane de?ned by the three equatorial car-bon atoms (D Sn(1)(plane):0.356(4)A
?;D Sn(2)(plane):0.160(4)A
?)[14],and the shorter Sn(2)···Cl(1)distance compared with Sn(1)···Cl(2%).The last mentioned Sn···Cl distances are consider-ably shorter than the sum of corresponding van
der Waals radii (3.85A
?[15])and indicate substan-tial bonding.Finally,the small difference of 0.062A
?between the bond lengths Sn(1)–Cl(3)and Sn(2)–Cl(2)re?ects the shortening of axial Sn–Cl bonds in a trigonal–bipyramidal ligand polyhedron,with increasing deviation from the ideal geometry towards a monocapped tetrahedron.
Both the Sn–C bond lengths and the bond lengths and angles at the phosphorus atoms show
[{Me 2(Cl)SnCH 2CH 2PPh 2}2Rh(CO)Cl] toluene /100°C /2d
?CH 4,?C 2H 4
[{Me(Cl)SnCH 2CH 2PPh 2}2Rh ?111111111o
(CO)Cl]
(2)
12no particularities and agree with values in litera-ture.
The yellow crystals melt at 155°C and are solu-ble in aromatic and chlorinated hydrocarbons.A
strong absorption at 2047cm ?1in the CO valence
D .Kruber et al ./Journal of Organometallic Chemistry 572(1999)117–123
120
T a b l e 2C h a r a c t e r i s t i c N M R d a t a f o r 1a n d 2
2
J (H C S n )(H z )
C o m -S o l v e n t l (119S n )(p p m )n
J (S n ,R h )(H z )n
J (S n ,P )(H z )l (31P )(p p m )
2J (P R h P )(H z )1J (P R h )(H z )
n
J (P ,S n )(H z )
l (1H )(S n C H 3)p o u n d
(p p m )
C 6
D 6
112.6(m )B 1a ,b
203.2a ,c
30.5(d )338.9a
122.1198.7a ,c
10.56(s )60.2C D 2C l 2
319.4(‘t ’)(S n 1)e 331.9d
84.3/96.6a
54.8(m )2
310.5
92.584.6/93.3a
?0.28(s )56.8249.7(m )(S n 2)e 221.9d 118.4/145.1a 63.9(m )90.1113.7/141.3a 0.05(s )
56.5
a
C a l c u l a t e d .b 4
J (S n C C P R h ).c 3J (S n C C P ).d 1J (S n R h ).e A t o m -n u m b e r i n g ,s e e F i g .2.
D .Kruber et al ./Journal of Organometallic Chemistry 572(1999)117–123121
region of the IR spectrum of 2in CsBr indicates the change of 1to a rhodium(III)complex [2,18].
2.5.Molecular structure of
[{Me (Cl )SnCH 2CH 2PPh 2}2Rh ?111111111o
(CO )Cl ](2)
The solid state structure of 2consists of discrete monomeric units separated by normal van der Waals contacts.An overall view of the molecule with the atom-numbering scheme is shown in Fig.2.Selected bond lengths and angles are listed in Table 3.The main feature of the structure of 2are the two ?ve-membered P,Sn,and Rh containing heterocycles with a covalent tin–rhodium bond and the short Sn(2)···Cl(1)contact
of 3.140(3)A
?(sum of the van der Waals radii:3.85A ?[15]).The rhodium atom is situated in an octahedral ligand sphere.The two phosphorus atoms are trans and the tin atoms are cis to one another.The octahedron is distorted at the Cl(1)edge by the Cl(1)···Sn(2)interac-tion (Cl(1)–Rh–Sn(2)75.1(1)°,Cl(1)–Rh–C(5)105.4(1)°,Cl(1)–Rh–Sn(1)160.7°(1))and by the P–Rh–Sn angle depression as result of the chelate ring formation (P(1)–Rh–Sn(1)83.6(1)°,P(2)–Rh–Sn(2)83.5(1)°).The Sn–Rh bond lengths agree with values described in the literature [16,17].Due to the higher trans in?uence of the CO ligand compared with that of
the Cl ligand the Rh–Sn(2)distance is with 2.634(1)A
?sligthly longer than the Rh–Sn(1)bond length (2.592(1)A
?).Both the two phosphorus and the two tin atoms exhibit a tetrahedral coordination,but,the deviation from the ideal geometry is in case of the tin atoms higher.
The ?ve-membered chelate rings show an envelope conformation.Sn,P,Rh and one C atom nearly form a plane,and one ring is puckered at the C(1)and the other one at the C(4)atom.
Table 3
Selected bond lengths (A
?),angles (°)and endocyclic torsion angles (°)for [{MeSnCH 2CH 2PPh 2}2R ?11111111o
h(CO)Cl](2)
Bond lengths (A
?) 2.592(1)Rh–Sn(1)Sn(2)–C(3) 2.168(5)Rh–Sn(2)Sn(2)–C(7)2.634(1) 2.135(5)Rh–P(1) 2.370(1)Sn(2)–Cl(3) 2.474(1)Rh–P(2) 2.365(1)P(1)–C(2) 1.856(5)1.840(4)P(1)–C(8)Rh–C(5) 1.942(4)P(1)–C(14) 1.837(4)Rh–Cl(1) 2.514(1)2.159(5)Sn(1)–C(1)P(2)–C(4) 1.842(4)Sn(1)–C(6) 2.133(7)P(2)–C(20) 1.835(5)2.430(1) 1.836(4)Sn(1)–Cl(2)P(2)–C(26)Bond angles (°)P(1)–Rh–P(2)178.8(1)C(6)–Sn(1)–Cl(2)100.8(2)160.7(1)Sn(1)–Rh–Cl(1)Rh–Sn(2)–C(3)102.1(1)172.2(1)Sn(2)–Rh–C(5)Rh–Sn(2)–C(7)128.0(2)Sn(1)–Rh–Sn(2)86.5(1)Rh–Sn(2)–Cl(3)115.4(1)Sn(1)–Rh–P(1)83.6(1)C(3)–Sn(2)–C(7)113.0(2)96.5(1)Sn(1)–Rh–P(2)Cl(3)–Sn(2)–Cl(3)98.4(1)96.5(2)C(7)–Sn(2)–Cl(3)Sn(1)–Rh–C(5)93.6(1)95.3(1)Sn(2)–Rh–P(1)Rh–P(1)–C(2)114.2(2)Sn(2)–Rh–P(2)Rh–P(1)–C(8)83.5(1)113.5(1)Sn(2)–Rh–Cl(1)117.2(1)Rh–P(1)–C(14)75.1(1)92.4(1)P(1)–Rh–C(5)C(2)–P(1)–C(8)102.6(2)92.1(1)P(1)–Rh–Cl(1)C(2)–P(1)–C(14)105.2(2)88.7(1)P(2)–Rh–C(5)C(8)–P(1)–C(14)102.6(2)P(2)–Rh–Cl(1)87.4(1)Rh-P(2)-C(4)113.5(2)C(5)-Rh-Cl(1)105.4(1)Rh-P(2)–C(20)116.4(1)101.1(1)Rh–Sn(1)–C(1)Rh–P(2)–C(26)114.6(1)C(4)–P(2)–C(20)131.1(2)Rh–Sn(1)–C(6)106.1(2)C(4)–P(2)–C(26)105.8(1)102.9(2)Rh–Sn(1)–Cl(2)C(1)–Sn(1)–C(6)101.7(2)
C(20)–P(2)–C(26)
114.4(2)C(1)–Sn(1)–Cl(2)
99.1(1)
Torsion angles (°)Rh–P(1)–C(2)–C(1)44.8(4)
36.6(4)Rh–P(2)–C(4)–C(3)P(2)–C(4)–C(3)–Sn(2)P(1)–C(2)–C(1)–Sn(1)?41.9(4)?50.1(4)41.6(3)C(2)–C(1)–Sn(1)–Rh 22.3(3)C(4)–C(3)–Sn(2)–Rh 1.4(1)C(3)–Sn(2)–Rh–P(2)C(1)–Sn(1)–Rh–P(1)?16.5(1)Sn(2)–Rh–P(2)–C(4)?4.9(2)
Sn(1)–Rh–P(1)–C(2)?21.2(2)
2.6.NMR spectroscopy of 2
The NMR data in Table 2indicate that the structure of 2in solution is identical with that in the solid state.Furthermore,the molecular geometry causes the chemi-cal nonequivalence both of the two tin and phosphorus atoms and also of the two tin methyl groups and the eight methylene protons in the chelate rings.Because of the proportion of only 8.58%for the NMR active 119Sn isotope (see Section 2.3)three isotopomers of 2with the spin systems ABX,ABLX,and ABMX (A,B =31P,L =119Sn(1),M =119Sn(2),X =103Rh)exist.Therefore,the main signals in the 31P-NMR spectrum which are doubled by the P–Rh coupling represent the AB part of the ABX spin system (l :54.8ppm,1J (31P 103Rh)=92.5Hz;l :63.9ppm,1J (31P 103Rh)=90.1Hz).The decrease of the 1J (31P 103Rh)coupling constant for 2compared with 1demonstrates the increase in the oxi-
Fig.2.Molecular structure of [{MeSnCH 2CH 2PPh 2}2R ?11111111o
h(CO)Cl](2)with the atom-labeling scheme.Hydrogen atoms and the solvent molecule (C 6H 6)are omitted for clarity.
D .Kruber et al ./Journal of Organometallic Chemistry 572(1999)117–123
122dation state from Rh(I)to Rh(III)[18].The 119Sn satellite signals in the 31P-NMR spectrum represent the AB part of the ABLX and the ABMX spin sys-tems mentioned above.At the present stage of our studies an assignment of the 31P-NMR signals is not possible.
The 119Sn-NMR spectrum exhibits a multiplet at 249.7ppm and a virtual triplet at 319.4ppm.Both signals are doubled by Sn–Rh coupling.The assign-ment of the two 119Sn-NMR signals is based on the different trans in?uence of the CO and the Cl ligand.With respect to the higher trans in?uence of CO (see Section 2.2)the 1J (119Sn(2)103Rh)coupling constant of 221.9Hz is 110Hz smaller than the 1J (119Sn(1)103Rh)coupling.Therefore,the high-?eld 119Sn-NMR signal at 249.7ppm can be assigned to the Sn(2)atom and the signal at 319.4ppm to the Sn(1)atom.The low-?eld position of the latter signal is also in agreement with the high electronegativity of the Cl atom in the trans position.Each 119Sn nucleus couples with both phosphorus nuclei,but,in a different way.The 2
J (119SnRh 31P)is the one coupling the other one n
J (119Sn,31P)represents the sum of the two contribu-tions 2J (119SnRh 31P) and 3J (119SnCC 31P) within the chelate ring.The coupling constants are determined by computer simulation using the 119Sn-NMR spectrum and the satellite part of the 31P-NMR spectrum.As mentioned above an assignment of the n J (119Sn,31P)coupling constants to a certain phosphorus atom is not possible.
The signi?cant down ?eld shift both of the 31P and the 119Sn-NMR signals is due to the fact that these atoms are included in a ?ve-membered ring (‘ring ef-fect’of chemical shifts [19]).We have observed the same effect for the bicyclic platinum complex [{Me 2SnCH 2CH 2PPh 2}2?1111111o
Pt][4].
The values of 211and 224Hz,respectively,for the n
J (H,Sn)coupling constant for two of the four PCH 2-protons in the chelate rings of 2are remarkably high.Our knowledge about the mechanism of the trans-formation of 1into 2is only vague.Certainly,the ?rst step is the intramolecular oxidative addition of the Sn–C(Me)bond of one ligand to the Rh(I)centre of 1.Efforts to detect the resulting intermediate complex failed.The higher reactivity of a Sn–C bond com-pared with a Sn–Cl bond in oxidative additions of triorganotin halides also is described for the reaction of R 3SnCl with Pd 0and Pt 0complexes [20].The in-tramolecular rearrangement of the intermediate com-plex to 2by demethylation both of the Rh atom and the tin atom of the second ligand is accompanied by the formation of methane and ethylene in a molar ratio of 2:1.This could be proved by gas-chromato-graphic investigation of the reaction.
3.Experimental
All manipulations were performed under dry argon.Elemental analyses were carried out at the Microana-lytical Laboratory of the Chemical Department.In-frared spectra were measured on a Specord 75IR (CsBr).The NMR spectra were recorded on Gemini 200(Varian)or Unity 500(Varian)spectrometers.Sol-vent signals (1H,13C),Me 4Sn (119Sn)and 85%H 3PO 4(31P)were used as references.The NMR spectra simu-lations were performed with the program PERCH [21].The molecular weight determination of 1was performed in benzene at 45°C (concentration =0.01mol l ?1)using a Knauer osmometer.
3.1.[{Me 2(Cl )SnCH 2CH 2PPh 2}2Rh (CO )Cl ](1)
Solutions of [Rh(CO)2Cl]2(300mg,0.77mmol)and Me 2(Cl)SnCH 2CH 2PPh 2[3](613mg, 1.54mmol)in benzene (in each case 10ml)are dropped simulta-neously in pure benzene (50ml)and the mixture is stirred for 2h to give a light yellow solution.During the reaction the equivalent amount of CO (35ml)is released.After evaporation of the solvent the residue is washed with pentane and dried in vacuo.1is ob-tained as a yellow ?ne-crystalline compound (1.4g,96%);m.p.124–126°C.
C 33H 40Cl 3OP 2RhSn 2(961.3):anal.(exp./calc.)C,41.51/41.23;H, 4.22/4.19;IR (CsBr,cm ?1):1975(CO).1H-NMR (C 6H 6):l 0.56(s,6H,SnC H 3,2J (H,Sn)60.2Hz); 1.43(m,4H,SnC H 2); 2.84(m,4H,PC H 2,3J (H,Sn)70Hz);6.99–7.68(m,20H,PC 6H 5)ppm.
3.2.[{Me (Cl )SnCH 2CH 2PPh 2}2Rh ?111111111o
(CO )Cl ](2)
A solution of 1(1.0g,1.04mmol)in toluene (50ml)was heated under stirring for 2days whereby it slowly turned from yellow to orange.The solvent was removed and the yellow residue recrystallized from CH 2Cl 2/hex-ane giving pure 2(560mg,61%);m.p.155°C.
C 31H 34Cl 3OP 2RhSn 2(931.2):anal.(exp./calc.)C,40.53/39.98;H 4.53/3.68;Cl 11.42/12.03;IR (CsBr,cm ?1):2047(CO).1H-NMR (C
D 2Cl 2):l ?0.28(s,3H,SnC H 3,2J (H,Sn)56.8Hz);0.05(s,3H,SnC H 3,2
J (H,Sn)56.5Hz);1.46(m,1H,SnC H 2);1.84(m,2H,SnC H 2);1.92(m,1H,SnC H 2);2.35(m,1H,PC H 2);2,58(m,1H,PC H 2);2.96(m,1H,PC H 2,3J (H,Sn)211Hz);3.60(m,1H,PC H 2,3J (H,Sn)224Hz);7.37–8.20(m,20H,PC 6H 5)ppm.
3.3.Crystallographic studies
Crystal data and details of the data collection and re?nement of 1and 2are summarized in Table 4.
D.Kruber et al./Journal of Organometallic Chemistry572(1999)117–123123
Table4
Crystal data and details of data collection and re?nement for1and 2
12
C34H37OCl3RhSn2
C33H40Cl3OP2RhSn2
Formula
970.22
961.23
Formula weight
(g mol?1)
P21/n
P21/c
Space group
Temperature240K r.t.
Lattice parameters
13.521(2)
18.590(10)
a(A?)
10.499(1)
11.514(3)
b(A?)
c(A?)18.812(8)25.761(2)
i(°)107.66(5)91.574(13)
3655.4(8)
3837(3)
Cell volume(A?3)
4
4
Formula units/unit cell
1.763
1.664
D calc.(g cm?1)
4.22–52.30 4.18–51.74
2q Range(°)
?23to23;?12to?16to16;?12 Range of h,k,l
14;?22to23to12;?31to31 Re?ections measured2413126217
Re?ections unique74886804
5147
Re?ections observed
(I o]2.0|(I o))
R int0.0717
0.0611
7488/5226804/520
Data/parameters
0.922 1.075
Goodness-of-?t(F2)
R1/wR2(F2)(all data)0.0615/0.06910.0396/0.0923
0.0329/0.06210.0302/0.0746
R1/wR2(F2)
(I o]2.0|(I o))
Min./max.residual?0.754/1.327
?0.388/0.745
electron density
(e A??3)Acknowledgements
The authors thank the Deutsche Forschungsgemein-schaft and the Fonds der Chemischen Industrie for ?nancial support.
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.