Inorg. Chem. 1985, 24, 1935-1939 Table I. Gas Products of Reaction Systems Containing H2N202in 5.0 M HCIOl at 25 C2HsOHas Chain Inhibitor
(PN0)O = 0; 1o5(nHzN202)O
OC,
A. No C2H50HAdded" 18 0.28 24 0.31 87 0.55 67 0.32 98 0.32 118 0.29 166 0.29
5.93
(PN0)O = 43.8 torr; 105(nHzN20z)o = 4.44
1935
with and without Added NO and with and without
0.48 0.43 0.22 1.04 1.56 1.71 1.77
0.41 0.45 0.67 0.65 0.83 0.78 0.81
8.52 4.98 6.13 6.80
0.17 0.10 0.075 0.11 0.095 0.080 0.054
0.55 0.83 1.06 0.54 0.76 0.85 0.99
2.53 3.55 2.92 3.47
B. 0.5 mL of C,H,OH Added" - 0.47 0.75 0.98 0.49 0.69 0.79 0.94
46 170 210 42 96 163 250
PNoo = 0; 105(nHzN202)0 = 4.42 PNoo = 50.9 torr; 105(nH2Nzo2)o = 5.26
"Total solution volume 10.0 mL. Table 11. Mass Spectrometric Analyses of N20Product of H2N202 Decomposition and Reaction with I5NO (96.2%) in 5.0 M HC104 at 25 OC fraction 5% I5N
of total N,O
e/m
in total N,O
A. No C2H50HAdded PNoo 45.0 torr; 46 0.1725 1 0 5 ( n ~ z ~ z 0= z ) 4.59; 0 t = 190 h 45 0.4547 44 0.3728 PNOO
+
HONNOH
+ -0NNOH
+ 2 N 0 + Nz + OH + H20 +
(16) Acknowledgment. The authors gratefully acknowledge the North Atlantic Treaty Alliance's support of their collaboration. Registry No. NO, 10102-43-9; H2N202,14448-38-5.
40.0
+
B. 0.5 mL of C2H50HAdded = 36.0 torr; t = 250 h 46 0.1542 45 44
0.0239 0.8219
16.6
In the absence of chain inhibition, the free radical OH may interact with -0NNOH to yield NO (eq 7) and with NO to yield HNOz (eq 8). The latter will in turn be expected to undergo disproprotionation to yield NO and NO3- (eq 9), so that some nitrate should be found among the NO-HZNzO2reaction products (but has not been observed directly by us). The near randomness of isotopic distribution observed in NzO in the non-chain-inhibited case indicates that it is produced largely by HNO dimerization, so that H atom abstraction on the part of unlabeled NO clearly comes into play on an important scale in this case (eq 10). This downgrades the importance of eq 4 as an N 2 0source. To account for this and to identify the major source of the very abundant Nz product, as well as of OH radicals, we postulate attack of NO at oxygen on .ONNOH to produce these two products, plus NOz (eq 11). Through its expected disproportionative hydrolysis (eq 12), the NOz will become a further source of both HN02 and NO3-. The reaction pathway described above is summarized in eq 7-14 of Scheme I. Scheme I OH + .ONNOH 2N0 HzO (7)
- + + + + + + + - + + + + + + - + 15N0
3Hl5No2 NO
NO
In addition to the above scheme, the possible reactions eq 15 and 16 have been postulated by Buchholz and Powell; however, these seem less plausible to us than eq 7-14. HONNOH NO HNOZ + N2 OH (15)
OH
215N0
HONNOH
+ .ONNOH
2N02
H15N02
H+
NO3-
HNO
(8)
H20
-0NNOH
(9) (10)
ONONNOH
NO2
N2
HzO
H+
NO3-
(12)
I5NI5NO H 2 0
(6)
HI5NO
HISNO + HNO HNO
HNOz
-+ HI5NO
OH (1 1)
L/z15NN0 + '/2N'5NO+ H,O (1 3)
HNO
N20
+ H20
(14)
0020-1669/85/1324-1935$01.50/0
Contribution from the Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
Synthesis and X-ray Structural Characterization of a Bimetallic Rh-Au Complex with Bridging 2-[Bis(diphenylphosphino)methyl]pyridine (PNP) Ligands Robert J. McNair, Per V. Nilsson, and Louis H. Pignolet* Received August 24, 1984
Heterobimetallic complexes with bidentate phosphine and phosphine-pyridine type ligands to hold two metals in close proximity have received considerable attention in recent years.'-1° Bifunctional ligands such as 2-(diphenylphosphino)pyridine, PhzPpy, have proved to be particularly useful in constructing (1) Farr, J. P.; Olmstead, M. M.; Balch, A. L. Znorg. Chem. 1983,22, 1229. (2) Farr, J. P.; Wood, F. E.; Balch, A. L. Znorg. Chem. 1983, 22, 3387. (3) Guimerans, R. R.; Wood, F. E.; Balch, A. L. Znorg. Chem. 1984, 23, 1307. (4) Farr, J. P.; Olmstead, M. M.; Rutherford, N. M.; Wood, F. E.; Balch, A. L. Organometallics 1983, 2, 1758. ( 5 ) (a) Wood, F. E.; Olmstead, M. M.; Balch, A. L. J. Am. Chem. SOC. 1983, 105, 6332. (b) Wood, F. E.; Hvoslef, J.; Balch, A. L. J. Am. Chem. SOC.1983, 105, 6986. (6) Langrick, C. R.; Pringle, P. G.; Shaw, B. L. Znorg. Chim. Acta 1983, 76, L263. (7) Blagg, A.; Hutton, A. T.;Pringle, P. G.; Shaw, B. L. Znorg. Chim. Acta 1983, 76, L265. (8) Cooper, G. R.; Hutton, A. T.; McEwan, D. M.; Pringle, P. G.; Shaw, B. L. Znorg. Chim. Acta 1983, 76, L267. (9) Hutton, A. L.; Pringle, P. G.; Shaw, B. L. OrganomeZallics 1983, 2, 1889. (10) Hoskins, B. F.; Steen, R. J.; Turney, T.W. Znorg. Chim. Acta 1983, 77, L69.
@ 1985 American Chemical Society
Notes
1936 Inorganic Chemistry, Vol. 24, No. 12, 1985 heterobimetallic species.'-5 We recently reported t h e synthesis and structural characterization of several mono- and binuclear complexes of R h and Ir with the potentially tridentate ligand,
Table I. Summary of Crystal Data and Intensity Collection for Compound 2
2- [bis(diphenylphosphino)methyl]pyridine, [Ph2Pl2CHCSH5N = PNP.'I-I3 We now report on t h e synthesis a n d X-ray structural characterization of a PNP-bridged heterobimetallic complex of R h and Au, [ R ~ A U ( ~ P N P ) ~ ] B F , N inOwhich ~ , the phosphorus atoms are arranged cis on the rhodium atom and trans on the gold a t o m (vide infra). This is t h e first Rh-Au phosphine complex t h a t has been characterized by single-crystal X-ray diffraction. Experimental Section
cryst syst space gP cryst dimens, mm3 cell parameters a, A 6, A
Physical Measurements. 31P(lH}N M R spectra were recorded at 121.5 MHz at 25 OC with use of a Nicolet NT-300 spectrometer. The chemical shifts are reported in ppm relative to the external standard 85% H3P04, with positive shifts downfield. IR spectra were recorded on a Beckman Model 4250 grating spectrometer using KBr disks. Preparation of Compounds. All manipulations were carried out under a purified N 2 atmosphere, using standard Schlenk techniques. [Rh(nbd)(PNP)]BF, (nbd = norbornadiene) and Au(PPh3)N03 were prepared according to literature [Rh(PNP),]BF, (1) was prepared by the reaction of [Rh(nbd)(PNP)]BF4 with a stoichiometric amount of P N P ligand in acetone solution. The product was precipitated with diethyl ether and collected by filtration. Yellow crystals were obtained by solvent diffusion from methylene chloride and diethyl ether: yield 50%; 31P(1HJ N M R (CH2C12) 6 1.06 (d, JRtP= 115.6 Hz); IR v(py-CN) = 1588 cm-I. Anal. Calcd for CmHSoBF,N,P,Rh: C, 64.75; H, 4.54; N, 2.52; P, 11.10. Found: C , 63.57; H , 4.56; N, 2.39; P, 10.81. [R~Au(PNP)~]BF,NO,( 2 ) was prepared by reaction of [Rh(PNP),]BF, with 2 equiv of Au(PPh3)N03 in methylene chloride solution. The initial yellow solution immediately changed to orange-red upon addition of the Au(PPh3)N03. Precipitation with diethyl ether gave an orange-red product: yield 82%; 3'P{1H}N M R (CH2C12) 6 76.02 (d of sym 4-line mult separated by ca. 162 Hz, Int = I), 60.29 (sym 4-line mult, Int = 1); IR v(Pyr-CN) = 1600 cm-I, v(BF4-) = 1090 cm-I (br), v(NO
