Organometallics 1986,5, 379-380
some additional reactions. The agreement is highly satisfactory, especially in view of the fact that most of the ab initio calculations were carried out a t a very high level. The calculated enthalpies of activation reaction also show good agreement, except for reactions involving hydrogen migration. MNDO is well-known to give values that are much too large in such cases. Acknowledgment. This work was supported by the Air Force Office of Scientific Research (Contract No. F49620-83-C-0024) and The Robert A. Welch Foundation (Grant F-126), The National Science Foundation (Grant CHE82-17948), and the Tektronix Foundation. The calculations were carried out by using a DEC VAX 11/780 computer purchased with funds provided by the National Science Foundation and The University of Texas a t Austin. Registry No. SiH, 13774-94-2;SiH2,13825-90-6;Si, 7440-21-3;
N
a
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SiF2, 13966-66-0; SiC12, 13569-32-9; SiBr2, 14877-32-8; SiH,, 7803-62-5; SiH3(CH3), 992-94-9; SM2(CHJ2,1111-74-6;SiH(CH3),, 993-07-7; Si(CH3)4,75-76-3; SiHz(C2H5)2, 542-91-6; SiH(C2H5),, 617-86-7;Si(C2H5),,631-36-7;Si2& 1590-87-0; Si3H8,7783-26-8; (C2H5)SiH3,2814-79-1; H2C=CHSiH3, 7291-09-0; HCZCSi, 1066-27-9; SiBr, 12350-21-9; H3SiBr, 13465-73-1; (CH3),SiBr, 2857-97-8; SiBr,, 7789-66-4; SiC1,13966-57-9;H,SiCl, 13465-78-6; (CH3),HSiC1,1066-35-9; (CH,)#iCl, 75-77-4; H2SiC12,4109-96-0; (CH3)SiC12H,75-54-7; (CH3)2SiC12, 75-78-5; HSiCl,, 10025-78-2; Sic4,10026-04-7; (CH3)SiC13,75-79-6; SiF, 11128-24-8; H,SiF, 13537-33-2;H&IiF2,13824-36-7;HSiF3,13465-71-9;Sip,, 7783-61-1; (CH3)SiH2F, 753-44-6; (CH3)SiHF2, 420-34-8; SiI, 13841-19-5;SiO, 10097-28-6; (SiH,)SO, 99583-30-9; (CH3),SiI, 16029-98-4; (CH3),SiOH, 1066-40-6;HN(Si(CH3)3)2, 999-97-3;Si2(CH3)6, 145014-2; (SiH3)20,13597-73-4;ISiH, 36098-67-6;ISiH,, 13598-42-0; ISiF,, 16865-60-4; SiHD,, 13537-02-5;Si2HD5,77815-94-2;HSiOH (trans),83892-34-6;cyclopropyl-SiH02,92917-37-8;H2Si=SiH2, 15435-77-5; HSi
