Subject: AM1/d thermochemistry of Ti compounds

From: [email-masked] (Alexander Voityuk)
Date: Thu, 18 Dec 1997 10:00:19 +0100

Hi,
Some days ago there was a question about AM1 calculation of Ti compounds.
Using the AM1/d method with preliminary parameters for Ti, one can obtain
quite reasonable estimation of thermochemical data and geometries of 
Ti containing molecules (see below). I think it would be interesting 
to compare AM1/d and PM3/tm results. Could anyone to provide CCLers
with PM3/tm data? 
To finish the AM1/d parameterization for Ti more experimental  or calculated
data on geometries and enthalpies of formation for compounds of Ti in the
gas phase are needed. Could anyone provide me with such data or/and the
corresponding  referencies?
With best regards 
        Alexander A. Voityuk

     Calculated and observed heats of formation (kcal/mol)
 
Molecule              Exp.     AM1/d     

Ti   s2d2  3F        112.3     112.3         
Ti   s1d3  5F        131.0     131.1         
Ti+  s1d2  4F        271.2     271.2         
Ti+  s0d3  4F        273.5     274.3         
Ti++ s0d2  3F        585.6     585.1         
Ti(CH3)4               4.3       2.0         
Ti(C6H6)+            229.2     213.4         
Ti(C5H5)2H2           72.4      70.4         
Ti(C5H5)2(CH3)2        1.1      12.9         
TiCp2Ph2              83.7      73.8         
TiCp2(CH2Ph)2         66.8      65.7         
Ti(C5H5)2(N3)2       121.0     120.2         
TiCp2(OPh)2          -70.9     -75.7         
Ti(C5H5)2(OOCCF3)2  -512.2    -515.0         
Ti(C5H5)2(OOCCCl3)2 -230.6    -232.5         
TiCp2(OOC-Ph)2      -161.9    -158.7         
Ti(C5H5)2(SCH3)2     -13.1     -15.2         
Ti(C5H5)2(SC2H5)2    -25.2     -27.2         
TiCp2(SPh)2           35.1      45.2         
Ti(C5H5)2(CH3)Cl     -29.8     -27.9         
Ti(C5H5)2F2         -156.8    -155.1         
TiCp2PhCl              9.8       1.8         
Ti(C5H5)2Cl2         -63.2     -64.2         
Ti(C5H5)Cl3         -121.0    -131.0         
Ti(C5H5)2I2           -6.8     -17.2         
Ti[N(CH3)2]4         -82.4     -78.3         
TiF4                -370.8    -369.7         
TiCl4               -182.4    -181.5         
TiBr4               -131.5    -131.1         
TiI4                 -66.3     -62.1         
TiOCl2              -130.4    -145.7         
 
MEAN ERROR ( 31 comparisons )  -1.66
MEAN ABSOLUTE ERROR             4.26

     Bond lengths (A) and bond angles (degrees)
 
Molecule                 Variable    Exp.   AM1/d   
 
Ti(CH3)4                  Ti-C       1.950   2.021      
 
Ti(C5H5)2H2               Ti-C av.   2.372   2.373      
 
TiCp2(OPh)2               Ti-Cp      2.420   2.416      
                          Ti-O       1.907   1.838
                          O-Ti-O      98.1    96.8
 
TiCp2(OOC-Ph)2            Ti-C(Cp)   2.381   2.389      
                          Ti-C(Cp)   2.369   2.371
                          Ti-C(Cp)   2.385   2.394
                          Ti-O       1.930   1.857
                          O-Ti-O      91.5    85.4
 
Ti(C5H5)2(SCH3)2          Mo-S       2.398   2.324      
                          S-Mo-S      93.8    99.6
 
Ti(C5H5)2(SC2H5)2         Mo-S       2.395   2.324      
                          S-Mo-S      99.3    99.7
 
Ti(C5H5)2Cl2              Ti-C av.   2.372   2.403      
                          Ti-Cl      2.318   2.224
                          Cl-Ti-Cl    97.1    94.6
 
Ti(C5H5)2I2               Ti-C av.   2.372   2.406      
 
Ti[N(CH3)2]4              Ti-N av.   2.000   1.884      
                          N-Ti-N     109.5   110.0
 
TiF4                      Ti-F       1.754   1.740      
 
TiCl4                     Ti-Cl      2.170   2.126      
 
TiBr4                     Ti-Br      2.340   2.341      
 
TiI4                      Ti-I       2.546   2.482      
 
TiOCl2                    Ti=O       1.601   1.594      
                          Ti-Cl      2.239   2.168
                          O=Ti-Cl    115.5   111.2