N-Functionalization of the Tetrahedrane Fe2(CO)6(/Z-SNH)

N-Functionalization of the Tetrahedrane Fe2(CO)6(/z-SNH) Max Herberhold*, Uw e Bertholdt, Wolfgang M ilius, Bernd Wrackmeyer Laboratorium für Anorganische Chemie, Universität Bayreuth, D-95440 Bayreuth Dedicated to Prof. Dr. Lothar Beyer on the occasion of his 60th birthday Z. Naturforsch. 51 b, 1283-1289 (1996); received March 27, 1996 Azadiferrathia, Tetrahedrane, Cluster Anion, Element-Nitrogen Bonds, NMR Spectra The azadiferrathia tetrahedrane, Fe 2(CO)6(£/-SNH) (1), was deprotonated to give the anion [Fe2(CO)6(/J-SN)]_ (2) which reacts with halides of phosphorus, arsenic, silicon, germanium, tin and boron by formation of element-nitrosen bonds. The new compounds were characterized by their IR. NMR('H, mB, i3C, i5N, 29Si,3 P, m Sn)and mass spectra. The molecular structure of [Fe2(CO)6(A/-SN-SiMe2CH 2-)]2 (11) was determined by X-ray structure analysis (space group Pi; triclinic; a = 799.8(2), b = 958.5(2), c = 1035.7(2) pm, a = 86.30(2)°, (3 = 81.27(2)°, 7 = 69.90(2)°).

Introduction Results and Discussion The reaction of carbonyliron complexes with Syntheses bis(trimethylsilyl)sulfurdiimide, The reactions of the anion 2 with various element Me3Si(NSN)SiMe3, followed by chromatography halides are summarized in Scheme 1. Apparently, on silica, leads to the azadiferrathia tetrahedrane any triorganosilyl, -germyl or -stannyl chloride can 1 [1]. The corresponding anion 2 is formed by be used to prepare complexes of the type 3-5. The deprotonation using sodium [2], "BuLi in hex reactions of 2 with bis(chlorosilyl) compounds, as ane or DBU (l,8-diazabicyclo[5.4.0]undec-7-ene) shown in Scheme 2, afford the new compounds 9 [3] [eq. (1)]. It was already shown that 2 reacts - 11, of which 11 was studied by X-ray diffraction with Me^'BuSiCl to give the N-silylated complex (vide infra). Fe2(CO)6(//-SN-SiMe2'Bu) [2], and that N-organo- It appears that the reaction of 2 with arsenic chlo substituted derivatives Fe 2(CO)6(/u-SN-R) are ac rides is also straightforward, and the products 6a and cessible from the reaction of 2 with carbenium or 6b are isolated in moderate to good yields. In con trialkyl oxonium cations [3], These successful trans trast, 'BU2PCI does not react with 2. If the reaction formations of 2 prompted us to start a systematic of 2 with either 'PnPCl or Cy 2PCl is monitored by study of the N-functionalization of 1. Here we de IR spectroscopy , the presence of the desired prod scribe the new complexes which contain group 15 ucts can be observed for about 5 - 1 0 min at -78°C, (phosphanyl, arsanyl), group 14 (silyl, germyl. stan- but thereafter decomposition into unidentified com nyl) and group 13 (boryl) substituents at the nitrogen pounds takes place, as is also apparent from the atom. 11P NMR spectra of reaction solutions. However, it turns out that 2 reacts with cyclic diaminophospho- rus halides bearing bulky substituents ('Bu groups) (i) at the nitrogen atoms to give reasonably stable prod / -N»7 V © N ------S x A N S ucts (7a, 7b). Compounds 7c and 7d with the less / > < S \ ------5Ü------/ X \ \ bulky N'Pr groups had to be characterized at low (OC)3Fe —------Fe(CO)3 -C4H10, -Li (OC^Fe ------Fe(CO>3 temperature. \ DBU f 2 The boron-substituted tetrahedranes 8 can be readily isolated if at least one dialkylamino group is linked to boron. All attempts to obtain dialkyl- boryl derivatives failed. Although 2 reacts with the 9-BBN derivatives 9-chloro- and 9-methoxy- * Reprint requests to Prof. Dr. M. Herberhold. borabicyclo[3.3.1 jnonane, it was not possible so

M RR' R,R'M 3a Si Me Me \ 3b Si Me H N ------S 3c Si Me ‘Bu /,X\ 3d Si Me SiM e, (OC )3Fe ______Fe( CO)3 3e Si 'Bu H 3 f Si Ph ’Bu 3. 4. 5 4 Ge Me Me 5a Sn Me Me A 5b Sn Et Et tßu,As \ R,RMC1 N ------S -er / X } , R R (OC)3F e ______Fe(C O )3 ^ \ t B u , A s C l ( PCI ( p 6a -er \ © N ------S R R N ------S / > v -CI /X\' (O C ),F c _ ------_F e(C O )3 (OC)3Fe ______Fe(CO)3 r °, f ASCI. As k Ö \ R f \ N ------S 7a ‘Bu (C H ,), ‘Bu (C H ,), A X s > RRBCI 7b (OC)3F c ______F e(C O )3 'Pr (C H ,), -er 7c 7d ‘Pr (S iM e,), 6b

RR'B RR N ------S 8a N'Pr, N'Pr, / X c 8b N(Bu)CH:CH:NBu (OC)3Fe ______F e(C O )3 8c N M e2 Fe Scheine 1

^ SiMe,SiMe2v^ sr > N ' ' n —- s / / W / x \ \ (OC)3Ft------Fe(CO)3 (OC)3Fe------Fe(CO)3

CISiMe2SiMe2Cl -2CI"

° Nc > s 2 / ^ \N (OC)3Fe—------Fe(CO)3 ClSiMe2OSiMe2Cl ClSiMe2CH2CH2SiMe2Cl -2 C r -2 CI'

^ SiMe,OSiMe,^ ^ SiMe2CH2CH2SiMe^ S -—- N N ----- S S----- N ----- S // X \ / X o / / V \ / X \ - (OC)3Fe------Fe( CO )3 (OC )3Fe ------Fe(CO)3 (OC)3Fe------Fe(CO)3 (OC)3Fe------Fe(CO)3 10 11

Scheine 2 M. Herberhold et al. • N-Functionalization of the Tetrahedrane Fe 2 (CO)6 (//,-SNH) 1285

Table I. I5N, 2ySi and 31P NMR data of the tetrahedranes spectra (see Experimental part). In the IR spectra the 3 and 7 (chemical shifts [ppm], coupling constants [Hz], z/(CO) absorptions appear as a characteristic pattern solvent: CaD^, 25°C). of five or six bands indicating a Fe 2(CO)6 unit of b'5 N <$29Si 1 y(29si, I5n ) Cs or lower symmetry [5]. In the mass spectra, the molecular ions are detected together with fragments 3a -359.2 35.5 5.6 generated by stepwise loss of CO. 3b -370|al 22.1 3c -371.0 35.6 5.6 The nature of the element-nitrogen bonds in 3 - 3d -362.1 -19.7 (SiMe->), 3.9 11 is of particular interest. In the cases of 3 and 32.1 (SiMei) 7, LiN NMR spectra were measured (Table I), in 3e -374,0 30.8 addition to 29Si or 11P NMR spectra (cf. Figures 1 3f [d] 9.8 and 2), and chemical shifts <5ll9Sn and 6n B were <515N ^31P '7(3IP,I5N) determined for compounds 5 and 8.

7a|b| -292.0 (cycle), 137.5 59.6 (cycle). The magnitude of the coupling constants -292.2 (Fe.SN) 99.6 (Fe-iSN) l'7(29Si,15N)l is small, similar to '7(29Si,l5N) in 2,5- 7b|b| -296.6 (Fe2SN), 119.6 94.0 (FeiSN), dihydro-1,2,5-azoniasilaboratoles 16,7], in which -300.3 (cycle) 72.0 (cycle) an ammonium-type nitrogen atom is present. The 7c [d] 136.1 intensities of the 29Si satellites in the l5N NMR 7d|c| 168.1 [d] spectra of 3 are somewhat higher than expected. [a]: <5(14N); [b]: -20°C; [c]: <$(29Si) = -4.6ppm, 27(31 P,29Si) It is therefore assumed that 57Fe satellites over = 11.7Hz; [d]: not measured. lap with the 29Si satellites. The coupling constants 'y(57Fe,l5N) are in the same order of magnitude far to isolate well-defined products. The n B NMR (« 6 Hz [2]) as *y(29Si,15N). In the case of 7, as in spectra of reaction solutions indicate the formation other phosphorus-nitrogen compounds [8], the mag of (9-BBN)tO (b 11 B = 58.0 [4]) which suggests an nitude and the sign (usually positive; reduced cou unexpected course of these reactions. pling constant 1 K(31 P,I5N) < 0) of the coupling con stants 17(3IP,15N) are dominated by the phosphorus Spectroscopic results atom, in particular by the influence of the lone pair of electrons [9]. Therefore, the '/ ( 3IP,15N) values All compounds 3 -1 1 were characterized by IR, of 7 are rather similar to those measured for deriva 'H and l3C NMR. and in most cases by El mass tives in which the azadiferrathia tetrahedrane unit is replaced by the Me2N group [10]. The neighbour-

S(,5N) -290 -300 Fig. 1. 30.4 MHz l3N NMR spectrum of 6(15N) Fe2(CO)6(//-SN-SiMe2?Bu) (3c) (saturated in CaD^, 25°C), measured by using the refocused INEPT pulse Fig. 2. 30.4 MHz 15N{1H} NMR spectrum of sequence (based on 37(lsNSiC'H) « 1.5 Hz). 2ySi satel Fe2(CO)6[/i-SN-P(NCBu)CH2)->CH'>] (7b) (1 g in C7DS, lites are marked with arrows. -20°C. 1286 M. Herberhold et al. ■ N-Functionalization of the Tetrahedrane Fe 2 (CO)6 (^ -S N H )

Table II. Selected bond lengths |pm] and angles [°J in 0(4) [Fe2(CO)6(//-SN-SiMe2CH2‘'-)]2 (11).

S-N 169.2(3) Fe( 1)- S - Fe(2) 69.4( 1) Fe( 1) - Fe(2) 250.6(1) Fe( 1) - S - N 58.4( 1) Fe( 1) - N 194.8(3) Fe(2) - S - N 58.0(1) Fe(2)- N 194.4(2) Fe( 1) - Fe(2) - S 55.1(1) Fe(1)- S 219.8(1) Fe(2) - Fe( 1)- S 55.5( 1) Fe(2)- S 220.7(1) N - Fe( 1) - S 47.7(1) N -S i 178.5(3) Fe(l) - N -Si 134.3(1) F e (l)-C (l) 179.5(4) Fe(2) - N -Si 138.9(2) Fe(1)-C(2) 179.3(3) S - N - Si 129.1(1) Fe(1)-C(3) 180.8(3) C(8) - Si - C(9) 112.7(1) Fig. 3. Molecular structure of Fe(2)- C(4) 180.2(4) Si - C(7) - C(7A) 116.3(4) [Fe2(CO)6(/u-SN-SiMe2CH2-)]2 (11). F e(2)- C(5) 180.2(4) Fe( 1) - N - Fe(2) 80.2(1) Fe(2)- C(6) 179.7(3) Fe( 1) - N -S 73.9(1) tetrahedrane units in 11 and in Fe 2(CO)6[/*-SN- Si - C(7) 186.5(3) Fe(2) - N -S 74.4( 1) C(7) - C(7A) 154.3(6) Fe( 1) - Fe(2) - N 50.0(1) C7H7Mo(CO)3] [3]. This is also true for the ge C(l)-0(1) 113.6(5) Fe(2)- Fe(l) - N 49.8(1) ometry of the CO ligands and their eclipsed ar C(2) - 0(2) 113.7(4) N - Fe(2) - S 47.6(1) rangement. The Si-N bonds [178.5(3) pm] in 11 C (3 )- 0(3) 113.2(4) N - Si - C(7) 108.8(1) are longer than in N-silylamines (172.5 - 174.0 pm C(4) - 0(4) 112.6(5) N - Si - C(8) 103.4(1) [18]), as expected for an ammonium-type nitrogen C(5) - 0(5) 113.1(5) N - Si - C(9) 107.4(2) C(6)- 0(6) 113.7(4) C(7) - Si - C(8) 112.6(2) atom. In a binuclear Fe(II) complex containing the Si -C(8) 185.2(3) C(7) - Si - C(9) 111.5(1) organo-substituted 2,5-dihydro-1,2,5-azasilabor-1 - Si - C(9) 185.5(3) yl groups both in bridging positions between the two iron atoms and in terminal positions, the Si- hood to an ammonium-type nitrogen atom causes N bond lengths are 175.6(4) pm and 172.9(5) pm deshielding for 29Si [6, 7], and also for 11B [ 11 J,31P for the four- and three-coordinate nitrogen atom, [12], and ll9Sn [13]. A comparison of the relevant respectively [19]. data for compounds 3, 5, 7 and 8 shows the same trend. Therefore, the bonding situation at the nitro Conclusions gen atom corresponds to that of an ammonium-type The N-functionalization of the parent complex nitrogen, at least as far as the element-nitrogen bond 1 by the reaction of its anion 2 with various ele is concerned. The <§15N values of compounds 3 and ment halides takes place smoothly in the case of 7 are found in the usual range of amines bearing triorganosilyl-, -germyl-, -stannyl-, arsanyl, and di- silyl or phosphanyl substituents [14]. alkylaminoboryl chlorides. The behaviour of phos phorus halides and of boron halides without a stabi X-ray structure analysis of lizing dialkylamino group is less predictable. Chem [FeiiCOj^ip-SN-SiMeiCHi-jh (H) ical shifts <315N, <5nB, 629S'i, 63IP, and <$ll9Sn, as Suitable single crystals of 11 (Scheme 2) were ob well as coupling constants '7(29Si,15N) all indicate tained from a concentrated CH 2CI2 solution with an that the cluster nitrogen atom possesses ammonium upper layer of hexane. Table 2 gives characteristic character. Coupling constants */(3lP,15N) are less bond distances and angles [15], and the molecular indicative since their magnitude (and sign) is dom structure of 11 - with a center of inversion between inated by the influence of the lone pair of electrons the atoms C(7) and C(7a) - is shown in Fig. 3. The S- at the phosphorus atom. N bond [169.2(3) pm] in 11 is slightly shorter than in Fe2(CO)6[//-SN-C7H7Mo(CO)3] [171.0(2) pm] Experimental [3], Ru2(CO)6(//-SN-'Bu) [170.5(4) and 172.6(4) All compounds were handled under an atmosphere pm] [16], and Fe3(CO)9(//-S)(//-SN-'Bu) [170.0(2) of dry argon, and the solvents were carefully dried. pm] [17], but is clearly in the range of S-N single The starting materials were prepared following litera bonds. Altogether, there are only marginal differ ture procedures: Fe2(CO)6(//-SNH) (1) [1], triethyltin ences in bond distances and angles between the chloride [20], l,3-di-/m-butyl-2-chloro-l,3-diaza-2- M. Herberhold et al. • N-Functionalization of the Tetrahedrane Fe 2 (CO)6 (/<-SN H ) 1287 phosphacyclopentane, -cyclohexane und 2-chloro-1,3- (Fe2SNSi+, 30). - IR (cm '): A/(CO)(hexane): 2076 (m), diisopropyl-1,3-diaza-2-phosphacyclopentane [21], 2034 (vs), 2000 (vs), 1990 (s), 1981 (m). - 'H NMR 2-chloro-1,3-diisopropyl-4,4,5,5-tetramethyl-1,3-diaza- (C6D6): 6'H = -0.13 (SiMe2), 4.37 (SiH), '/(^Si.'H) 2-phospha-4,5-disilacyclopentane [22], = 212 Hz. - l3C NMR (C6D6): <513C = -1.4 (SiMe2), di-/m-butyl-chloro-arsane [23], '7(29Si,l3C) = 57.1 Hz, 209.6 (CO). 2-chloro-1,3-dioxa-2-arsacyclopentane [24], Fe2(CO)b(SN-SiMe 2 Bu) (3c) [2]: Orange crystals, chlorobis(diisopropylamino)borane [25], yield 94%. - EI-MS, m/e (%): 441 (M+, 35), 273 (M+- 1,3-dibutyl-2-chloro-1,3-diaza-2-boracyclopentane [26], 6CO , 100), 217 (Fe2SNSiMe2H+, 40). - IR (cm“ 1): chloro(ferrocenyl)dimethylaminoborane [27]. i/(CO)(hexane): 2075 (m), 2032 (vs), 1999 (vs), 1988 Butyl lithium in hexane, trimethyltin chloride, trimethyl- (s), 1977 (m), 1947 (w). - 'H NMR (C6D6): 6'H = -0.09 germanium bromide, all chlorosilanes and DBU were (SiMe2), 0.71 (C(CH3)3). - l3C NMR (C6D6): 6 l3C = -2.3 used as commercial products. (SiMe2), 18.7 (C(CH3)3), 26.1 (C(CH3)3), 209,9 (CO). IR spectra: Perkin Elmer 983G - Mass spectra: Fe2(CO)()(SN-SiMe2SiMei,) (3d): Orange oil, yield Finnegan MAT 8500 - NMR spectra: Bruker ARX 250, 95%. - EI-MS, m/e(%) 457 (M+, 65), 289 (M+-6CO, 100), Bruker AC 300 and Bruker AM 500, all equipped with 273 (Fe2SNSi2C4H, i+, 40). - IR (cm“ 1): ^(CO)(hexane): multinuclear units; 'H (Me4Si, C6Ü6: 6 7.15), <$'3C 2074 (m), 2031 (vs), 1998 (vs), 1987 (s), 1977 (m), 1972 (Me4Si, C6D6: 6 128.0); bu B (Et20-B F 3, H (n B) = (w). - ' H NMR (C6D6): <$'H = 0.02 (SiMe3), 0.08 (SiMe2). 32.083791 MHz), 6I5N (MeN02, H (,5N) = 10.136767 - 13C NMR (C6D6): <$13C = -2.4 (SiMe3), '7(29Si,'3C) = MHz), <529Si (Me4Si, E (29Si) = 19.867184 MHz), <53'P 45.7 Hz, 1.2 (SiMe2), ’y(29Si,'3C) = 46.8 Hz, 209.9 (CO). [H3P 0 4(85% aq), £ ( 3IP) = 40.480747 MHz], <$‘19Sn Fe2(CO)t(SN-Si'B112H) (3e): Orange oil, yield 51%. - (Me4Sn, ^ (1 ,ySn) = 37.290665 MHz). Measurements EI-MS, m/e (%) 469 (M+, 10), 301 (M+-6CO, 100), 245 were carried out at 25 ± l°C,exeptfor lriNNMRof7aand (Fe2SNSiC4Hi i+, 65). - IR (cm“ ' ): ^(CO)(hexane): 2075 7b (-20°C) using saturated solutions in 5mm (o.d.) tubes. (m), 2033 (vs), 1998 (vs), 1990 (s), 1979 (m). - 'H N M R i5N NMR spectra were measured either directly with in (C6D6): 6'H = 0.90 (C(CH3)3), 3.96 (SiH), '7(29Si,' H) = verse gated 1H decoupling (compounds 7) or by using the 209 Hz. - 13C NMR (C6D6):<,)'3C = 21.1 (C(CH3)3), 28.2 refocussed INEPT pulse sequence (based on long range (C(CH3)3), 209.6 (CO). '■"'N-'H scalar coupling) with 'H decoupling [28] (com Fe2(CO)b(SN-Si!BuPli 2) (3f): Orange oil, yield 43%. pounds 3). All 29Si NMR spectra were measured by using - EI-MS, m/e (%) 564 (M+, 6), 397 (M+-6CO, 50), 341 the INEPT pulse sequence with 'H decoupling [28], (Fe2SNSiHPh2+, 50),263 (Fe2SNSiPh+,15). - IR (cm“ '): i'(COMhexane): 2074 (m), 2032 (vs), 1998 (vs), 1990 N-Substituted azadiferrathia tetrahedranes (3 - 11). Gen (s), 1977 (m). - !H NMR (C6D6): 6*H = 1.10 (C(CH3)3), eral procedure 37(29Si,'H) = 126 Hz. 7.56 (Ph), 7.75 (Ph). - ,3C NMR (C6D6): 6 i3C = 20.2 (C(CH3)3), 27.9 (C(CH3)3), 128.1 (o- A solution of about 200 mg of Fe2(CO)6(//-SNH) Ph), 131.0 (p-Ph), 132.6 (ipso-Ph), 136.3 (m-Ph), 209.4 (about 0.6mmol) in hexane (or thf for 9-11) was reacted (CO). at -78°C with the stoichiometric amount of the deproto- Fe2(CO)t,(SN-GeMey) (4): Orange crystals, m.p.: 89- nating agent (usually BuLi. DBU for 3a - 3f, 8a - 8c and 90°C(decomp.), yield 86%. - EI-MS, m/e (%): 445 (M+, 9 - 11). The hexane suspension (or thf solution in the 50), 277 (M+-6CO, 100), 247 (Fe2SNGeCH3+, 75). - IR cases of 9 - 11) was stirred for a few minutes, and the (cm“ 1): z/(CO)(hexane): 2072 (m), 2029 (vs), 1996 (vs), stoichiometric amount of the appropriate halogeno com 1983 (s), 1975 (m), 1968 (w). - 'H NMR (C6D6): 6 ] H pound was then added. After stirring for about 1 h (3 d = 0.04. - l3C NMR (C6Dft): 613C = 1.4 (GeMe3), 210.4 for 3f), the suspensions were decanted or filtrated and the (CO). desired tetrahedranes were isolated by evaporation of the Fe2(CO)b(SN-SnMe 3) (5a) [2]: Orange crystals, m.p.: solvent. 42-45°C(decomp.), yield 53%. - EI-MS,: m/e (%): 491 Fe2(CO)t(SN-SiMey) (3a) [I]: Orange crystals, m.p.: (M+, 35), 323 (M+-6CO, 100), 278 (Fe2SNSn+, 70). - 46-48°C, yield 85%. - EI-MS, m/e (%): 399 (M+, 25), IR (cm“ '): i/(CO)(hexane): 2069 (m), 2025 (vs), 1982 231 (M+-6CO, 100), 186 (Fe2SNSi+,55). - IR (cm“ '): (vs), 1978 (s), 1963 (m). - ' H NMR (C6D6): 6 1H = -0.02, ^(CO)(hexane): 2072 (m), 2032 (vs), 1992 (vs), 1986 27("9Sn,'H) = 56.5 Hz. - l3C NMR (C6D6): 613C = -3.4 (s), 1976 (m), 1966 (w). 'H NMR (C6D6): 6'H = -0.16 (SnMe3), '7 (" 9Sn,l3C) = 375.4 Hz, 210.7 (CO). - " 9Sn (SiMe3). - l3C NMR (C6D6): <513C = 1.0 (SiMe3), 209.9 NM R(C6D6): ^ 1 l9Sn = 207.0. (CO). Fe2(CO)(,(SN-SnEti) (5b): Orange crystals, m.p.: 41- Fei(CO)()(SN-SiMe2H) (3b): Orange oil, yield 99%. - 42°C(decomp.), yield 33%. - EI-MS, m/e (%): 533 (M+, EI-MS, m/e (%) 385 (M \ 14), 217 (M+-6CO, 100), 186 10), 365 (M+-6CO, 60), 279 (Fe2SNSnH+, 65), 159 1288 M. Herberhold et al. ■ N-Functionalization of the Tetrahedrane Fe 2 (CO)ö(//-SNH)

(Fe2SNH+, 100). - IR (cm ’): z/(CO)(hexane): 2067 (m), (CH3), 3J(3IP,I3C) = 8.8 Hz, 26.3 (d) (CH3),V(31P.I3C) = 2024 (vs), 1990 (vs), 1976 (s), 1962 (m). - 'H NMR 5.9 H z, 52.2 (d) (CH), 2J(3IP,I3C) = 40.3 Hz, 210.6 (CO). (CftDft): <5’ H = 0.95 (m, CH 2), 1.11 (m. CH3). - l3C NMR Fe2(CO)b[SN-B(N‘Pnh] (8a): Orange-red oil, yield (C6D6): ' 19Sn = 172.7. i'(COXhexane): 2070 (m), 2042 (vs), 1999(vs), 1990(s), Fe2(CO)b(SN-As'BinJ (6 a): Orange brown oil, yield 1976 (m). - 'H NMR (C 6D6): d'H = 1.18 (d, CH3), 3.39 76%. - EI-MS. m/e (%): 515 (M+, 5), 347 (M+-6CO, 55), (sept. CH). - "B NMR (C 6D6):<,»1IB = 30.6. - l3C NMR 289 (Fe2SNAsC4H8+, 100), 233 (Fe2SNAs+, 60). - IR (C6D6): 6 13C = 23.5 (CH3), 47.2 (CH). 208,9 (CO). (cm-1 ): ^(CO)(hexane): 2071 (m), 2030 (vs), 1995 (vs), Fe2(CO)t[SN-B(NBuCH2)2] (8b): Orange-red oil, 1987 (s), 1976 (m), 1970 (w). - 'H NMR (C6D6): ölH yield 68 %. - EI-MS. m/e (%) 507 (M+, 7), 339 (M+- = 0.94. - l3C NMR (C6D6): <513C = 28.3 (C(CH3)3, 41.3 6CO, 47), 86 (HOB(NHCH2)2+, 100). - IR (cm-1 ): (C(CH3)3, 209.9 (CO). i/(CO)(hexane): 2075 (m), 2033 (vs), 1995 (vs), 1989 Fe2(CO)b[SN-As(OCH 2)2] (6b): Orange crystals, de (s), 1980 (m). - 'H NMR (C 6D6): ö'H = 0.94 (q, CH3), composition: 90-92°C, yield 55%. - EI-MS, m/e (%) 461 1.27 (m, CH2CH2), 2.75 (s + t, cyclic-CH2 + Bu-CH2). - (M+, 41), 293 (M+-6CO, 100), 233 (Fe2SNAs+, 88). - IR 11B NMR (C6D6): 6 11B = 28.4. - 13C NMR (C 6D6): 6 l3C = (cm-1): (CO)(hexane): 2077 (m), 2038 (vs), 2002 (vs), 14.3 (CH3), 20.5, 31.9 (Bu-CH2), 46.0, 47.2 (cyclic-CH 2 1997 (s), 1985 (m). - 1H NMR (C6D6): <$'H =: 3.22, 3.63. + Bu-CH2), 209,8 (CO). - I3C NMR (C6D6): <5i3C = 68.3 (CH2), 209.5 (CO). Fe2(CO)e(SN-B(NMe2)Fc) (8c): Orange-red oil, yield 22%. - IR (cm-1 ): i/(CO)(hexane): 2072 (m), 2031 (vs), Fe2(CO)b[SN-P(NtBuCH 2)2] (7a): Orange brown oil, yield 89%. - EI-MS, m/e (%) 527 (M+, 1), 359 (M+-6CO, 1995 (vs), 1988 (s), 1977 (m). - 1H NMR (C 6D6): Ö]H = 2.47 (s, N(CH3)2), 3.98 (s, Cp), 4.09, 4.15 (vt, C 5H4). - 2,5), 234 (SP(H)(N;BuCH2)2+, 15), 203 (H2P('BuCH2)2+, 11B NMR (C6D6): <$" B = 38.2. - 13C NMR (C6D6): <^13C 100). - IR (cm-1): i/(CO)(hexane): 2068 (m), 2027 (vs), 1990 (vs), 1983 (s), 1973 (m), 1964 (w). - 'H NMR = 38.2, 41.9 (N(CH3)2), 69.2 (Cp), 69.6 (C 5H4, quart.), (C6D6): <5'H = 1.06 (C(CH3)3), 2.68 (m) (CH2), 3.17 (m) 70.9, 74.9 (C 5H4), 208,9 (CO). (CH2). - l3C NMR (C6D6): ö]3C = 30.1 (d) (C(CH3)3). [Fe2(CO)(,(SN-SiMe2-)]2 (9): Orange oil, yield 81%, V (31 P,I3C) = 10.2 Hz, 46.4 (d) (CH2), 27(31 P,13C) = 8.6 Hz, EI-MS, m/e (%) 740 (M+-CO, 0.5), 432 (M+-12CO, 100), 54.1 (d) (C(CH3)3), 2/( 3lP,13C) = 19.7 Hz, 210.8 (CO). 216 (Fe2SNSiMe2+, 40). - IR (cm-1): ^(CO)(hexane): 2074 (m), 2033 (vs), 2001 (vs), 1988 (s). - ’H NMR Fe2(COh[SN-P(N,BuCH2)2CH2] (7b): Orange brown (C6D6): <$'H = 0.46. - l3C NMR (C6D6): <5,3C = 2.0 oil, yield 94%. - EI-MS, m/e (%) 429 (M+-4CO, 2), (SiMe2), 209.8 (CO). - 29Si NMR (C 6D6): <529Si = 25.4. 373 (M+-6CO, 10), 215 (P(N'BuCH2)2CH2+, 100), 103 [Fe2(CO)ß(SN-SiMe2-)]2 0 (lO): Orange crystals, m.p.: (P(NHCH2)2CH2+, 100). - IR (cm-1 ): z/(CO)(hexane): 87-88°C (decomp.), yield 73%. - EI-MS,: m/e (%) 2068 (m), 2026 (vs), 1991 (vs), 1981 (s), 1971 (m). - 'H 756 (M+-CO, 5), 448 (M+-12CO, 100),418 (M+-12CO- N M R(C6D6):<()1H = 1.09(C(CH3)3), 1.67 (m) (CCH2C), C2H6, 80), 402 (M+-12CO-OMe2, 15), - IR (cm-1): 2.50 (m) (NCH2), 3.05 (m) (NCH2). - l3C NMR (C6D6): i/(CO)(hexane): 2077 (m), 2035 (vs), 2001 (vs), 1990 6I3C = 26.8 (CCH2C), 29.6 (d) (C(CH3)3), V(3IP,I3C) = (s), 1982 (m). - 'H NMR (C 6D6): <5‘H = 0.00. - l3C NMR 14.7 Hz, 39.5 (d) (NCH2), 2/( 31P,13C) = 5.0 Hz, 56.8 (d) (C6D6): <513C = 0.4 (SiMe2), 209.6 (CO). - 29Si NMR (C(CH3)3), 27(31P,i3C) = 28.0 Hz, 210.8 (CO). (C6D6): <529Si = 8.9. Fe2(CO)6[SN-P(NiPrCH2)2] (7c): Orange brown oil. [Fe2(CO)h(SN-SiMe2CH2-)]2 (11)-' Orange crystals, - IR (cm-1): t/(CO)(hexane): 2069 (m), 2027 (vs), 1992 m.p.: 52-56°C (decomp.), yield 95%. - EI-MS, m/e (%) (vs), 1983 (s), 1973 (m), 1965 (w). - 'H NMR (C6D6): 796 (M+, 2), 460 (M+- 12CO, 100), 432 (Fe 4S2N2Si2Me4+, b'H = 0.93 (CH(CH3)2, 0.99 (CH(CH3)2, 2.52 (CH2), 40). - IR (cm-1): ^(CO)(thf): 2073 (m), 2030 (vs), 1988 2.97 (CH2), 3.13 (CH(CH3)2. - 13C NMR (C6D6):: (^l3C (s). - 'H NMR (CD2C12): <*)'H = 0.23 (SiMe2), 0.59 = 22.4 (d) (CH3), V (3IP,I3C) = 8.2 Hz, 22.6 (d) (CH3), (SiCH2-). - ,3C NMR (CD2C12): <513C = -1.1 (SiMe2), 3([3IP,13C) = 7.1 Hz, 45.6 (d) (CH2), 2i( 31P,l3C) = 9.4 Hz, 9.7 (SiCH2-), 210.0 (CO). - 29Si NMR (CD 2CI2): <^29Si = 49.1 (d) (CH), 27(3 IP,i3C) = 23.1 Hz, 210.8 (CO). 26.5. F(?2(CO)()[SN-P(NiPrSiMe2)2] (7d): Orange brown oil. - IR (cm-1): ^(CO)(hexane): 2069 (m), 2027 (vs), 1997 X-ray crystal structure of (vs), 1991 (s), 1982 (m). 1971 (w). - 'H NMR (C6D6): Fe2(COk(f i-SN-SiMe2CH2CH2SiMe2-NS)Fe2(COh (11) 6*H = 0.15 (Si(CH3)3), 0.38 (Si(CH3)3), 1.08 (CH(CH3)2, Triclinic, a = 799.8(2), b = 958.5(2), c = 1035.7(2) 1.18 (CH(CH3)2, 3.59 (CH(CH3)2. - l3C NMR (C(lD6):: pm, a = 86.30(2)°, 0 = 81.27(2)°, 7 = 69.90(2), Z= 1, Ö]'C = 2.1 (Si(CH3)2), V(31P,I3C) = 4.9 Hz, 24.2 (d) space group P I, Dc = 1.794 gcm-3, orange needles: 0.22 M. Herberhold et al. ■ N-Functionalization of the Tetrahedrane Fe 2 (CO)ö(^-SNH) 1289 x 0.22 x 1.00 m m \ absorption coefficient: 2.211 mm-1 , transmission factors: 0.0288/0.0585), R/wR-value (w 1 = 4099 reflections measured in u;-26>-scan-mode, thereof a 2(F)): 0.0369/0.0324, min./max. residual electron den 3375 independent (F>0.0cr(F)), measured in the range of sity: -0.75/0.75 eÄ~3. 4°<20<55° on a Siemens P4 diffractometer (MoKa, A = 71.069 pm, graphite monochromator), 173K. The structure was solved by direct methods Acknowledgement (SHELXTL PLUS), all non-hydrogen atoms were refined with anisotropic temperature factors. Hydrogen atoms Support of this work by the Deutsche Forschungsge are on calculated positions, 182 parameters refined, em meinschaft (DFG) and the Fonds der Chemischen Indu pirical correction of absorption via -0-Scans (min./max. strie is gratefully acknowledged.

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