The coordinating properties of a variety of unsymmetrical uninegative tridentate chelating "pyrazolylgallate" ligands have been studied using the tricarbonyl moieties "M(CO)3", where M = Mn or Re, as acceptor species. A series of monomeric, pseudo octahedral complexes has been characterized and a fac mode of coordination established for the tridentate gallate ligands from 1H nmr, ir measurements, and X-ray structure determinations. Nitrosylation of a selection of the rhenium tricarbonyl compounds has yielded a number of cationic rhenium mononitrosyl dicarbonyl species. The reactivity of these cations towards reducing agents has been investigated.

, 633 (1984). The synthcsis, physical properties, and crystal structure of thc dirhodium spccics [ M C G~( N~C~H~) , ]~R~~(~-C O )~ containing thrcc carbonyl bridgcs are reported. Crystals of tri(~-carbonyl)bis~n~ethyltris(I-pyrazolyl)gallato]dirhodium -benzcnc (1 : I) are monoclinic, (I = 1 1.660(4), b = 15.29 17(7). c = 1 1.750(4) A, P = 1 19.09(1)", Z = 2, space group P 2 , . The structure was solved by conventional heavy-atom techniques and was refined by full-matrix Icast-squares procedures to R 0.030 and R,, = 0.033 for 2604 retlcctions with I 2 3u(1). The molecule contains a Rh-Rh single bond of 2.5818(8) A bridged by thrce CO ligands, the overall molccu$r symmctry being close to D,,,. Other important mcan structural parameters are: Rh-C = 2.007(10), Rh-N = 2.181(14) A, Rh-C-Rh = 80.1(5)", and Rh-C-0 = 140.0(7)".BRENDA M. LOUIE, STEVEN J. RETTIG, ALAN STORR et JAMES TROTTER. Can. J. Chem. 62, 633 (1984).On rapporte la synthkse. les propriCtCs physiques et la structure cristalline dcs dCriv@s du dirhodium [MeGa(NZC3H3)l2-Rh2(k-C0)? contenant trois groupcs carbonyles cn position de ponts. Les cristaux de tri(p-carbonyl)bis[mCthyitris(pyrazolyl-1)gallato]dirhodiumbenz6ne ( I : I) apparticnnent au groupe d'espace monoclinique P 2 , avcc ti = 11,660(4), I ? = 15,2917 (7) et c = 11,750(4) A. P = 119,09(1)", Z = 2. On a rksolu la structure par les techniques conventionnelles de I'atome lourd et on I'a affinke par la mkthodc dcs moindres carrcs (matrice cntiere) jusqu'a dcs valcurs de R = 0.030 et de R,,. = 0,033 pour 2604 rCflexions avec I 2 3a(l). La molCcule contient une liaison simple Rh-Rh dc 2,581 8(8) A maintenue en position de pont par trois ligands CO. la symCtric molCculairc globalc-cst voisine dc D3,,. Les principaux autres parametres structuraux moyens sont: Rh-C = 2,007(10), Rh-N = 2.18 l(14) A, Rh-C-Kh = 80.1(5)" et Rh-C-0 = 140,0(7)". [Traduit par le journal] IntroductionOur continuing investigations into the coordinating properties of pyrazolyl-gallate ligands have recently entered the fertile field of rhodium chemistry. Subtle differences between the cyclopentadienyl, C5H5-, and methyltris(1-pyrazolyl)gallate, MeGa(N2C,H,),-, ligands have been discussed in a previous publication (1). The present paper extends this theme in reporting the synthesis and structure of a unique dimeric rhodium system with three bridging carbonyl groups and end-capping MeGa(N?C,H,),-ligands, a compound having no counterpart in cyclopentadienyl rhodium carbonyl chemistry. Experimental Slarlitlg materialsAir-sensitive materials were handled in oxygen-frcc dry nitrogen. Tetrahydrofuran (THF) was dried by refluxing over sodium/benzophenone and used immediately following distillation. Benzene was dried by refluxing over molten potassium followed by distillation and methylene chloride by refluxing over PZOS prior to distillation.[Rh(CO)2C1]2 (Strem Chemicals) was sublimed itz vacuo before use. The sodium salt of the methyltris(1-pyrazoly1)gallate ligand, Na' [MeGa(N2C3H3),j. was prepared as a THF solution as described earlie...

Chem. 65, 445 (1987). NOMX6aromatic charge transfer complexes are formed from NOX and NbX5 or Tax5, where X may be F or C1 and the aromatic portion is a methyl-substituted benzene. NOMoF6, NOUF6, NOUF7, and NOWC17.aromatic complexes have been identified but only oxyfluoro species have been isolated when M is Mo, W, or U. NOTaC16,hexamethylbenzene crystallizes in the trigonal space group P 3 2 , with a = 9.822(3), c = 17.469 (7)

Inorg. Chem. 1985, 24, 1147-1 152 1147 complex)32 lies central at AH* = 6.3 kcal mol-I and AS* = -19.6 cal K-I mol-I. Four points are included for metalloprotein-metalloprotein reactions. Sutin, from a similar inspection of a more limited set of data for cytochrome c reactions, has suggested that metalloprotein-metalloprotein reactions are associated with more positive AH* and AS* values.38 This point does not appear to be confirmed from the more extensive comparison now possible. Implications of the correlation (and the line drawn) are that AG* -12 kcal mol-', and the isokinetic temperature is 40 OC.Since the rate constant k may be regarded as composite (=I&) whether or not limiting kinetics are observed, it can be presumed that AHo and ASo are a part of the correlation in Figure 8. A graph of all known AHo and ASo values ( Figure 9) gives an impressive correlation that is according to charge and consistent with AHo and ASo making major contribution to the separation of points in Figure 8. All the protein reactants in Figure 9 are negatively charged, with complexes 3+ (upper seven points) and 3-(lower points) and the triangle indicating parameters for the association of the 5-complex with cytochrome$ We also note that AH* values for the reactions of plastocyanin, PCu', and azurin, ACu', with [Fe(CN)6]3-and the 5-complex are negative and that the AHo component is likely to be negative therefore for these reactions.27 It is of further interest that three of the points in Figure 9 are for the [Co(4,7-DPSphen),13-complex (4,7-DPSphen = 4,7-bis(phenylsulfonato)phenanthroline), which has a large size and unusual charge distribution. A correlation for AHd* and AS&*, although giving a similar trend, shows much more scatter.The correlation in Figure 9 implies a common AGO of -4.6 kcal mol-' at a temperature close to 50 OC. On a cautionary note, we should add that although no AHo and ASo parameters are at present available for 4+ and 5+ complexes, it is unlikely that these will correlate in a similar fashion. Thus, K values for 4+ and 5+ complexes31 of -20000 M-' at 25 OC are unlikely to decrease to around 1000 M-' at 50 O C to conform to the correlation. Registry No. [(CN)5FeCNCo(CN)5]5-, 53535-93-6; [Fe(CN)6]3-, 13408-62-3; [C~(dipic)~]-, 7 1605-2 1-5; [ C~(bpy)~(O~CMe),l+, 16986-92-8; [Co(phen)J3+, 16788-34-4; [Zr(C20,),le, 21392-82-5; [Mo-(CN),le, 17923-49-8; cytochrome f, 9035-46-5. Supplementary Material Available: Listings of rate constants, Tables I-IV and VI-XI (12 pages). Ordering information is given on any current masthead page. Contribution from the The equilibrium constant and rate constants for the reversible 1: 1 complexation reaction Fe1'(TIM)(C6H5CN)?+ + CO 5 Fe11(TIM)(C6H5CN)(CO)2+ + C6H5CN have been measured in benzonitrile. At 25 OC, Kq = K/[C6H5CN] = kl'/k-, = 420 M-I, k,' = 0.14 M-' s-I, and k-, = 3.3 X ~O-'S-~.In CO-saturated solutions, the Fe(I1) complex can be oxidized electrochemically by a C,E,E,C, mechanism, which allows the diffusion coefficients of the complex and CO adduct to be determined....

Tertiary amines (CH3)2NR, where R is phenyl or a methyl-substituted phenyl group, in the presence of nitric oxide and a Lewis acid undergo -hydrogen cleavage concurrent with intermolecular hydrogen transfer to yield equal amounts of iminium and ammonium salts in CH2C12 as solvent. When R is a p-or o-methyl-substituted phenyl ring this facile hydrogen transfer reaction also takes place in S02. In CH2C12 no reaction occurs in the absence of the Lewis acid. However, in S02 or in CHC13 with the addition of stoichiometric amounts of S02 and no Lewis acid, H2S03 adducts of the tertiary amines form together with minor oxidation products. Pyridine and NO in S02, with or without a Lewis acid present, react to form the S03 amine adduct. This compound crystallizes in the monoclinic space group P21/n, with a = 5.5463 ( 12), b = 14.8124 (11), and c = 7.9267 (18) Á and ß = 104.06 (2)°. l,6-Dimethyl-3,4-dihydroquinazoline-4-sulfonate, a minor product formed along with the H2S03 adduct of jV,JV-dimethyl-p-toluidine, crystallizes in the monoclinic space group I2/m, with a = 10.6728 (4), b = 7.0426 (6), and c = 15.5537 (9) A and ß = 107.635 (4)°.