Chiral iridium(III) α-amino acidato complexes (RIr,SN,SC)- and (SIr,SN,SC)-[(η5-C5Me5)Ir(L-prolinate)(C?C_CMe3)]

Teti&&on:&wt~ Vol. 4. No. 7, pp. 1425-1428. 1993 Printedin GreatBritain

09574166/93 $6.Ihh,OO 0 1993 Pagamon hcss Ltd

Chiral ~~idium(II~ a-Gino Acid&o complexes (RI~,SN,SC)and (SIr,SN,Sc)-[(rrl5-C5Meg)Ir(L-prolinate)(CeC-CMej)]

Daniel Carmona,* Fernando J. Lahoz, Reinaldo Atencio, Luii A. Ore* Depdutpmentode QlhiCn Jnorgtic8,

IastituIo de CiePeia & Mate&l& de Aragbn,

Utiversidad de ZamgomCmse~ Sup&r de lrmstigaciw

CienMicns, So009 Zamgom (Spain)

M. Pilar Lamata and Emilio San Jo&

~~eceivedin UK 16 Murch 1993)

Abstract: Diastereomers (SIr,SN,SC)- and OIIr,SN,SC)-[(‘l5-CgMe5)Ir(L-piolinate)(~C-CMe3)]

have

been prepared and the structure of the later determined by X-ray diffraction methods.

We have recently reported the synthesis and characterkation of optically active amino acid&o complexes of the types [($k~Mq)M(aa)Cl] and [($CjMe$M(aa)(PPh3)]BFq (aa=Lamho acidate, M=Rh, Ir) in which the metal is a chiral centre.1 In view of the synthetic potential (e.g. asymmetric synthesis and catalysis) of chiral organotransition metal templatcs2-5we are in&e&d in the synthesis of these types of complexes in hom~~~l form. Here we report the successful preparation of the p~u~~~ [(115-C5Mes)~~-p~linate)(CoC-CMe3)1 (2) and the cry&I structure of its ~~~~i~y diastereomcr (RIr,SN,SC)-[($C@IeS)lr(L-pmlinate)(C=C-CMq)J

complex more stable

(2a).6

Complex [(~5-C5Me5)~(L”~oliMte)Cl] (1) (molar ratio R~,SN,SCISI&N,SC = 95131 reacts in methanol with ~chio~c amounts of NE&3and H-CGCMe3 to give a mixture of the two dab (RIr,SN,SC)- and (SIr,SN,SC)-[(q5-C~MeS)l+pfolinate)(C=C-CMe3)J (2a) and (2a’), respectively (Scheme 1). The more insoluble complex 2a’ [a& -4 (c 0.4, CHCl3) was isolated by pr&ipitation with diethyl ether (yield 50 %). Next, a methanolic solutkm of 2a’ was kept at rOOmtemperature. Epimerization 1425

D. CAFWONAet al.

1426

occurred over coume of 24 h to give pure the thermodynamically (c 0.4, CHC13). domplexes particular,

more stable 2a diastereomer

both diastereomers

present the same v(CW)

+31

meaus. In

vibration at co. 2115 cm”1 (nujol) and differ

significantly in their % NMR data.7 As expected, for epimers that differ in the conf$nration complexes

[a]~

%b and 2a’ have been characterized by analytical and spectroscopic

at metal.23 the

Za and 2a’ exhibit circular dichroism spectra that are roughly mirror images above 300 nm

(Ftgure 1).

[($-C~e&@+rolinate)CXl

H-C=C-CMe, NEt,

I

B’%gmwe I.iCD spectra of complexes Za (full line) and Za’ (dashed line) in chloroform.

1427

Chiil lr(EI) a-aminu acidato complexes

Single crystals of complex (R~~S~,~~2a

were gmwn by slow diffusion of hexane into a clefs

solution and its strudure was &z&m&d by an X-ray dif%action study* (Figure 2). The coordination around the iridium is pseudoctahedral. An +C$&j group occupies three fae lotion positions.One tertbu~la~~Ii~ group and the prolinate anion coordhmted through one oxygen and the nitrogen atom complete the coordMion sphere of the metal that displays an R absolute configmation. SM parameters of C5Me5 and ~~~

anions are similar to those found” in the related compIex 1.It is achy

well ~~~

that in chelate N,O pro&ate complexes the nitrogen atom adopts the same absolute ~fi~~tion

as the

asymmetric carbon.t~ This experimental fact, most probably due to steric xeasons, permit us to assign to the less stable dias&momer 2a’ the !Q&q,SC unction

Figure 2. ~01~~

structure of complex ~~,S~,S~-~.

Selected bond dis~cea (A) and angles (*) are as

follows Ir-O(1) 2.105(5), &N(l) 2.135(6), &C(6) 2+012(S),~~~~d

r$-CsMest 1.813(3), C(61-C(7)

1.2~(13), C(7)-C@) 1~486(14)~a-~-N(l) 78.3(2), 0(1)-M!(6) B&3), O(l)-Ir-G 131.8(2), N(l)+ C(6) S%(3), N(l)-IF-G 131.6(2), C(6)-1r-G 125.2(3), II+-C(6)-C(7)~~.~8), ~(6)~~~(8) ~79,~~O).

A~nowi~e~~~ We thank the Direcci& de ~ve~~i6n Cientifica y T&n&a for f&an&I snpport (Grant 87~) and the Venezuelan Conmjo Naeion& de In~~~~ Cientiiicas y Trolls for the award of a Research studenship to R.A.

1428

D. CARMONA et al.

References and Notes

1.

Carmona, D.; Mendora, A.; Lahoz, F.J.; Ore, L.A.; Lamam, M.P.; San Jose, E J. Organomet. Chent. c17.

1990,396, 2.

Consiglio, G.; Morandini, F. C’hem. Rev. 1987, 87, 761.

3.

Brunner, H. Mt. Organomet. Chern. 1980,18,

4.

Saura-Llamas, I.; Gladysz, J.A. J. Am. Chem. Sot. 1992, 114,2136. A.M.; Gladysz, !J.A. Organonutaliics ,1990,9, 1991.

5.

7.

313.

The descriptors R and S for atoms arc assigned

according Baird and Sloan’s proposals. Stanley, K.; Baird, MC. J. Am. Chem. Sot. 1975, 97, 6598. Sloan, T.E. Top. Stereo&em. 1981, 12, 1. lH NMR (6, CkKl3) 2a: 1.70 (15H, s, CgMeg), 1.16 (9H, s, CMej), 4.21 (lH, m, NH), 4.10 (lH, m, C*H), 3.41, 2.79 (2H, m, NCZQ),

2.26-1.80

CgMeg), 1.17 (9H, s, CMeJ), 5.24 (lH, m, NH), CH2-C*H). 8.

Bodner, G.S.; Peng, T-S; Arif,

Davies, S.G. C&em. Br., 1989,268. Davies, S.G.; Smallrldge, AJ. J. Orgarwmet. Chem. 1991, 413,

6.

151.

Crystal data: (RIr,SN,SC)-2a,

(4H, m, C&J-CH2).

28’: 1.69 (15H, s,

3.86, 3.22, 2.44, 2.13, 1.94 (7H, m, CH2-CH2-

C21H32IrN02, M = 522.71, orthorhombic,

space group P212121, a =

9.5178(10), b = 12.3851(16), c I 18.5850(17) A, U = 2190.8(4) A3,Z = 4, DC = 1585 g cm-s, F(OOO)= 1032, p(Mo Ka) = 60.83 cm -1, h = 0.71069 A. An orange prismatic block, 0.612 x 0.621 x 0.618 mm, wasused to collect intensities for 4633 reflections with 3 I 28 I 52O in a Siemens-Stce diffractometer. An empirical absorption correction was applied 4031 unique reflections with F0 I 4.0 o(F,) were used in the refinement. The structure was solved by Patterson, and AF synthesis. The tertbutyl group was observed disordered in two

positions (atoms C(9), C(10) and C( 11)). All non-

disordered non-hydrogen atoms were anisotropically refined. The quirality of the molecule has been checked using Rogers method (9 = 1.03(3)). Final agreement factors were R = 0.0345 and RW = 0.0375. Full details of the crystal

structure

analysis

have been deposited

at the Cambridge

Crystallographid Data Centm. 9.

Freeman, H.C.;. Maxwell, 1.E Znorg. Chem 1970, 9, 649. Freeman, H.C.; Marzilli, L.G.; Maxwell, I.E. Ztwrg. Chem. 1970, 9, 2408. Oki, H.; Yoncda, H. Znorg. Chem. 1981, 20, 3875. Erickson, L.E.; Jones, G.S.; Blanchard, Williams,

J-L_; Ahmed,

K.J. Znorg. Chem. 1991, 30, 3147. Birse, E.F.;

P.A.1 Stephens, F.; Vagg, R.S. Znorg. Chim. Acta 1988, 148, 63. Jones, P.; Williams,

P.A.; Stephen& F.S.;Vagg, RS. J. C%rd. Chem 1987, 16, 25. Ito, T.; Marumo, F.; Saito, Y. Acta Crystallogr., S&t. B, 1971, 27, 1062. Shamala, N.; Venkatesan, K. C?yst. +!buct. Commw 197% 2, 5. Padmanabhan, V.M.; Patel, R.P. Acta Cry% Sect. C, 1987, 43, 1064. Tsuboyama, S.; Matsudo, M.; Tsuboyama, K.; Sakurai, T. Acta Cryst.., Sect. C. 1989, 45, 872. Kramer, R.; Polborn, K.; Wanjek, H.; Z&II, I.; Beck, W. Chem. Ber. 1990,123, 767.